1
|
Abbas A, Hammad AS, Al-Shafai M. The role of genetic and epigenetic GNAS alterations in the development of early-onset obesity. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2024; 793:108487. [PMID: 38103632 DOI: 10.1016/j.mrrev.2023.108487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 12/06/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
BACKGROUND GNAS (guanine nucleotide-binding protein, alpha stimulating) is an imprinted gene that encodes Gsα, the α subunit of the heterotrimeric stimulatory G protein. This subunit mediates the signalling of a diverse array of G protein-coupled receptors (GPCRs), including the melanocortin 4 receptor (MC4R) that serves a pivotal role in regulating food intake, energy homoeostasis, and body weight. Genetic or epigenetic alterations in GNAS are known to cause pseudohypoparathyroidism in its different subtypes and have been recently associated with isolated, early-onset, severe obesity. Given the diverse biological functions that Gsα serves, multiple molecular mechanisms involving various GPCRs, such as MC4R, β2- and β3-adrenoceptors, and corticotropin-releasing hormone receptor, have been implicated in the pathophysiology of severe, early-onset obesity that results from genetic or epigenetic GNAS changes. SCOPE OF REVIEW This review examines the structure and function of GNAS and provides an overview of the disorders that are caused by defects in this gene and may feature early-onset obesity. Moreover, it elucidates the potential molecular mechanisms underlying Gsα deficiency-induced early-onset obesity, highlighting some of their implications for the diagnosis, management, and treatment of this complex condition. MAJOR CONCLUSIONS Gsα deficiency is an underappreciated cause of early-onset, severe obesity. Therefore, screening children with unexplained, severe obesity for GNAS defects is recommended, to enhance the molecular diagnosis and management of this condition.
Collapse
Affiliation(s)
- Alaa Abbas
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Ayat S Hammad
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, P.O. Box 2713, Doha, Qatar; Biomedical Research Center, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Mashael Al-Shafai
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, P.O. Box 2713, Doha, Qatar; Biomedical Research Center, Qatar University, P.O. Box 2713, Doha, Qatar.
| |
Collapse
|
2
|
Yang W, Zuo Y, Zhang N, Wang K, Zhang R, Chen Z, He Q. GNAS locus: bone related diseases and mouse models. Front Endocrinol (Lausanne) 2023; 14:1255864. [PMID: 37920253 PMCID: PMC10619756 DOI: 10.3389/fendo.2023.1255864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/29/2023] [Indexed: 11/04/2023] Open
Abstract
GNASis a complex locus characterized by multiple transcripts and an imprinting effect. It orchestrates a variety of physiological processes via numerous signaling pathways. Human diseases associated with the GNAS gene encompass fibrous dysplasia (FD), Albright's Hereditary Osteodystrophy (AHO), parathyroid hormone(PTH) resistance, and Progressive Osseous Heteroplasia (POH), among others. To facilitate the study of the GNAS locus and its associated diseases, researchers have developed a range of mouse models. In this review, we will systematically explore the GNAS locus, its related signaling pathways, the bone diseases associated with it, and the mouse models pertinent to these bone diseases.
Collapse
Affiliation(s)
- Wan Yang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yiyi Zuo
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Nuo Zhang
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Kangning Wang
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Runze Zhang
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Ziyi Chen
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Qing He
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| |
Collapse
|
3
|
Matarrese P, Maccari S, Gambardella L, Vona R, Barbagallo F, Vezzi V, Stati T, Grò MC, Giovannetti A, Catalano L, Molinari P, Marano G, Ambrosio C. Benzodiazepine diazepam regulates cell surface β1-adrenergic receptor density in human monocytes. Eur J Pharmacol 2023; 948:175700. [PMID: 37001579 DOI: 10.1016/j.ejphar.2023.175700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 03/31/2023]
Abstract
Downregulation of cell surface β-adrenergic receptors (β-AR) is an important adaptive response that prevents deleterious effects of receptor overstimulation. Various factors including reactive oxygen species cause β-AR downregulation. In this study, we evaluated the effects of ligands of the peripheral benzodiazepine receptor (PBR), a key protein in regulating oxidative stress, on surface density of endogenous β1-and β2-ARs in highly differentiated cells such as human monocytes, which express both β-AR subtypes. β-AR expression in human monocytes was evaluated by flow cytometry, qPCR and western blotting. Monocyte treatment with β-AR agonist isoproterenol did not change surface β1-AR density while downregulating surface β2-AR density. This effect was antagonized by the β-blocker propranolol. An opposite response was observed with benzodiazepine diazepam that led to a time-dependent reduction in β1-AR density. In particular, while no significant downregulation was observed after 3 h of treatment, only 63% of β1-ARs were still present on the cell surface after 48 h of treatment with diazepam at 1 μM. Treatment with the PBR antagonist PK11195, but not with propranolol, antagonized the effects of diazepam. No change in β1-AR-mRNA or protein levels was observed at any time after diazepam treatment. We also found that diazepam did not affect Gs-protein or β-arrestin-2 recruitment for both β-ARs in engineered fibroblasts, further suggesting that diazepam activity on β1-AR density is mediated by PBR. Finally, no sex-related differences were found. Collectively, these results indicate that monocyte β1-ARs are resistant to catecholamine-mediated downregulation and suggest that PBR plays an important role in regulating β1-AR density.
Collapse
|
4
|
Lauffer P, Zwaveling-Soonawala N, Li S, Bacalini MG, Naumova OY, Wiemels J, Boelen A, Henneman P, de Smith AJ, van Trotsenburg ASP. Meta-Analysis of DNA Methylation Datasets Shows Aberrant DNA Methylation of Thyroid Development or Function Genes in Down Syndrome. Thyroid 2023; 33:53-62. [PMID: 36326208 DOI: 10.1089/thy.2022.0320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background: In Down syndrome (DS), there is high occurrence of congenital hypothyroidism (CH) and subclinical hypothyroidism (SH) early in life. The etiology of CH and early SH in DS remains unclear. Previous research has shown genome-wide transcriptional and epigenetic alterations in DS. Thus, we hypothesized that CH and early SH could be caused by epigenetically driven transcriptional downregulation of thyroid-related genes, through promoter region hypermethylation. Methods: We extracted whole blood DNA methylation (DNAm) profiles of DS and non-DS individuals from four independent Illumina array-based datasets (252 DS individuals and 519 non-DS individuals). The data were divided into discovery and validation datasets. Epigenome-wide association analysis was performed using a linear regression model, after which we filtered results for thyroid-related genes. Results: In the discovery dataset, we identified significant associations for DS in 18 thyroid-related genes. Twenty-one of 30 significant differentially methylated positions (DMPs) were also significant in the validation dataset. A meta-analysis of the discovery and validation datasets detected 31 DMPs, including 29 promoter-associated cytosine-guanine dinucleotides (CpG) with identical direction of effect across the datasets, and two differentially methylated regions. Twenty-seven DMPs were hypomethylated and promoter associated. The mean methylation difference of hypomethylated thyroid-related DMPs decreased with age. Conclusions: Contrary to our hypothesis of generalized hypermethylation of promoter regions of thyroid-related genes-indicative of epigenetic silencing of promoters and subsequent transcriptional downregulation, causing biochemical thyroid abnormalities in DS-we found an enrichment of hypomethylated DMPs annotated to promoter regions of these genes. This suggests that CH and early SH in DS are not caused by differential methylation of thyroid-related genes. Considering that epigenetic regulation is dynamic, we hypothesize that the observed thyroid-related gene DNAm changes could be a rescue phenomenon in an attempt to ameliorate the thyroid phenotype, through epigenetic upregulation of thyroid-related genes. This hypothesis is supported by the finding of decreasing methylation difference of thyroid-related genes with age. The prevalence of early SH declines with age, so hypothetically, epigenetic upregulation of thyroid-related genes also diminishes. While this study provides interesting insights, the exact origin of CH and early SH in DS remains unknown.
Collapse
Affiliation(s)
- Peter Lauffer
- Department of Pediatric Endocrinology, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM) Research Institute, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Nitash Zwaveling-Soonawala
- Department of Pediatric Endocrinology, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM) Research Institute, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Shaobo Li
- Department of Population and Public Health Sciences, Center for Genetic Epidemiology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
- Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA
| | - Maria G Bacalini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Oxana Y Naumova
- Vavilov Institute of General Genetics RAS, Moscow, Russia
- Department of Psychology, University of Houston, Houston, Texas, USA
| | - Joseph Wiemels
- Department of Population and Public Health Sciences, Center for Genetic Epidemiology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
- Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA
| | - Anita Boelen
- Endocrine Laboratory, Department of Clinical Chemistry, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM) Research Institute, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Peter Henneman
- Department of Human Genetics, Amsterdam Reproduction & Development Institute, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Adam J de Smith
- Department of Population and Public Health Sciences, Center for Genetic Epidemiology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
- Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA
| | - A S Paul van Trotsenburg
- Department of Pediatric Endocrinology, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM) Research Institute, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
5
|
Kottler ML. Pseudo-hypoparathyroïdie et ses variants. Med Sci (Paris) 2022; 38:655-662. [DOI: 10.1051/medsci/2022103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Les pseudohypoparathyroïdies (PHP) sont des maladies rares, caractérisées par une résistance à l’action rénale de la parathormone. Le défaut génétique est localisé au locus GNAS, qui code la sous-unité alpha stimulatrice des protéines G (Gαs). Ce locus est le siège de régulations complexes, épissage alternatif et empreinte parentale éteigant de façon tissu-spécifique l’expression de l’allèle paternel. Des mutations hétérozygotes perte de fonction, des épimutations responsables d’une perte d’expression sont associées à un large spectre pathologique : PHP1A, PHP1B, ossification hétérotopique, ostéodystophie, obésité, retard de croissance in utero, etc., dont les mécanismes restent encore incomplètement connus.
Collapse
|
6
|
A Naturally Occurring Membrane-Anchored Gα s Variant, XLαs, Activates Phospholipase Cβ4. J Biol Chem 2022; 298:102134. [PMID: 35709985 PMCID: PMC9294334 DOI: 10.1016/j.jbc.2022.102134] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/02/2022] Open
Abstract
Extra-large stimulatory Gα (XLαs) is a large variant of G protein αs subunit (Gαs) that uses an alternative promoter and thus differs from Gαs at the first exon. XLαs activation by G protein–coupled receptors mediates cAMP generation, similarly to Gαs; however, Gαs and XLαs have been shown to have distinct cellular and physiological functions. For example, previous work suggests that XLαs can stimulate inositol phosphate production in renal proximal tubules and thereby regulate serum phosphate levels. In this study, we show that XLαs directly and specifically stimulates a specific isoform of phospholipase Cβ (PLCβ), PLCβ4, both in transfected cells and with purified protein components. We demonstrate that neither the ability of XLαs to activate cAMP generation nor the canonical G protein switch II regions are required for PLCβ stimulation. Furthermore, this activation is nucleotide independent but is inhibited by Gβγ, suggesting a mechanism of activation that relies on Gβγ subunit dissociation. Surprisingly, our results indicate that enhanced membrane targeting of XLαs relative to Gαs confers the ability to activate PLCβ4. We also show that PLCβ4 is required for isoproterenol-induced inositol phosphate accumulation in osteocyte-like Ocy454 cells. Taken together, we demonstrate a novel mechanism for activation of phosphoinositide turnover downstream of Gs-coupled receptors that may have a critical role in endocrine physiology.
Collapse
|
7
|
Mendes de Oliveira E, Keogh JM, Talbot F, Henning E, Ahmed R, Perdikari A, Bounds R, Wasiluk N, Ayinampudi V, Barroso I, Mokrosiński J, Jyothish D, Lim S, Gupta S, Kershaw M, Matei C, Partha P, Randell T, McAulay A, Wilson LC, Cheetham T, Crowne EC, Clayton P, Farooqi IS. Obesity-Associated GNAS Mutations and the Melanocortin Pathway. N Engl J Med 2021; 385:1581-1592. [PMID: 34614324 DOI: 10.1056/nejmoa2103329] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND GNAS encodes the Gαs (stimulatory G-protein alpha subunit) protein, which mediates G protein-coupled receptor (GPCR) signaling. GNAS mutations cause developmental delay, short stature, and skeletal abnormalities in a syndrome called Albright's hereditary osteodystrophy. Because of imprinting, mutations on the maternal allele also cause obesity and hormone resistance (pseudohypoparathyroidism). METHODS We performed exome sequencing and targeted resequencing in 2548 children who presented with severe obesity, and we unexpectedly identified 22 GNAS mutation carriers. We investigated whether the effect of GNAS mutations on melanocortin 4 receptor (MC4R) signaling explains the obesity and whether the variable clinical spectrum in patients might be explained by the results of molecular assays. RESULTS Almost all GNAS mutations impaired MC4R signaling. A total of 6 of 11 patients who were 12 to 18 years of age had reduced growth. In these patients, mutations disrupted growth hormone-releasing hormone receptor signaling, but growth was unaffected in carriers of mutations that did not affect this signaling pathway (mean standard-deviation score for height, -0.90 vs. 0.75, respectively; P = 0.02). Only 1 of 10 patients who reached final height before or during the study had short stature. GNAS mutations that impaired thyrotropin receptor signaling were associated with developmental delay and with higher thyrotropin levels (mean [±SD], 8.4±4.7 mIU per liter) than those in 340 severely obese children who did not have GNAS mutations (3.9±2.6 mIU per liter; P = 0.004). CONCLUSIONS Because pathogenic mutations may manifest with obesity alone, screening of children with severe obesity for GNAS deficiency may allow early diagnosis, improving clinical outcomes, and melanocortin agonists may aid in weight loss. GNAS mutations that are identified by means of unbiased genetic testing differentially affect GPCR signaling pathways that contribute to clinical heterogeneity. Monogenic diseases are clinically more variable than their classic descriptions suggest. (Funded by Wellcome and others.).
Collapse
Affiliation(s)
- Edson Mendes de Oliveira
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Julia M Keogh
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Fleur Talbot
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Elana Henning
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Rachel Ahmed
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Aliki Perdikari
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Rebecca Bounds
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Natalia Wasiluk
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Vikram Ayinampudi
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Inês Barroso
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Jacek Mokrosiński
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Deepthi Jyothish
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Sharon Lim
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Sanjay Gupta
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Melanie Kershaw
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Cristina Matei
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Praveen Partha
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Tabitha Randell
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Antoinette McAulay
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Louise C Wilson
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Tim Cheetham
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Elizabeth C Crowne
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - Peter Clayton
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| | - I Sadaf Farooqi
- From the University of Cambridge Metabolic Research Laboratories and National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge (E.M.O., J.M.K., F.T., E.H., R.A., A.P., R.B., N.W., V.A., J.M., I.S.F.), the Exeter Centre of Excellence for Diabetes Research, University of Exeter Medical School, Exeter (I.B.), Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham (D.J., M.K.), Broomfield Hospital, Chelmsford (S.L.), Hull University Teaching Hospitals NHS Trust, Hull (S.G.), East and North Hertfordshire NHS Trust Lister Hospital, Stevenage (C.M.), County Durham and Darlington NHS Foundation Trust, Darlington (P.P.), Nottingham Children's Hospital, Nottingham (T.R.), University Hospitals Dorset NHS Foundation Trust, Poole (A.M.), Great Ormond Street Hospital for Children NHS Foundation Trust, London (L.C.W.), the Translational and Clinical Research Institute, Newcastle University, and Great North Children's Hospital, Royal Victoria Infirmary, Newcastle upon Tyne (T.C.), University Hospitals Bristol and Weston NHS Foundation Trust, Bristol (E.C.C.), and the Division of Developmental Biology and Medicine, University of Manchester, Manchester (P.C.) - all in the United Kingdom
| |
Collapse
|
8
|
Cui Q, Aksu C, Ay B, Remillard CE, Plagge A, Gardezi M, Dunlap M, Gerstenfeld LC, He Q, Bastepe M. Maternal GNAS Contributes to the Extra-Large G Protein α-Subunit (XLαs) Expression in a Cell Type-Specific Manner. Front Genet 2021; 12:680537. [PMID: 34220953 PMCID: PMC8247768 DOI: 10.3389/fgene.2021.680537] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 05/12/2021] [Indexed: 11/25/2022] Open
Abstract
GNAS encodes the stimulatory G protein alpha-subunit (Gsα) and its large variant XLαs. Studies have suggested that XLαs is expressed exclusively paternally. Thus, XLαs deficiency is considered to be responsible for certain findings in patients with paternal GNAS mutations, such as pseudo-pseudohypoparathyroidism, and the phenotypes associated with maternal uniparental disomy of chromosome 20, which comprises GNAS. However, a study of bone marrow stromal cells (BMSC) suggested that XLαs could be biallelically expressed. Aberrant BMSC differentiation due to constitutively activating GNAS mutations affecting both Gsα and XLαs is the underlying pathology in fibrous dysplasia of bone. To investigate allelic XLαs expression, we employed next-generation sequencing and a polymorphism common to XLαs and Gsα, as well as A/B, another paternally expressed GNAS transcript. In mouse BMSCs, Gsα transcripts were 48.4 ± 0.3% paternal, while A/B was 99.8 ± 0.2% paternal. In contrast, XLαs expression varied among different samples, paternal contribution ranging from 43.0 to 99.9%. Sample-to-sample variation in paternal XLαs expression was also detected in bone (83.7-99.6%) and cerebellum (83.8 to 100%) but not in cultured calvarial osteoblasts (99.1 ± 0.1%). Osteoblastic differentiation of BMSCs shifted the paternal XLαs expression from 83.9 ± 1.5% at baseline to 97.2 ± 1.1%. In two human BMSC samples grown under osteoinductive conditions, XLαs expression was also predominantly monoallelic (91.3 or 99.6%). Thus, the maternal GNAS contributes significantly to XLαs expression in BMSCs but not osteoblasts. Altered XLαs activity may thus occur in certain cell types irrespective of the parental origin of a GNAS defect.
Collapse
Affiliation(s)
- Qiuxia Cui
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Cagri Aksu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Birol Ay
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Claire E. Remillard
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Antonius Plagge
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Mina Gardezi
- Department of Orthopaedic Surgery, Boston University School of Medicine, Boston, MA, United States
| | - Margaret Dunlap
- Department of Orthopaedic Surgery, Boston University School of Medicine, Boston, MA, United States
| | - Louis C. Gerstenfeld
- Department of Orthopaedic Surgery, Boston University School of Medicine, Boston, MA, United States
| | - Qing He
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- School of Stomatology, Wuhan University, Wuhan, China
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| |
Collapse
|
9
|
Luo D, Qi X, Liu L, Su Y, Fang L, Guan Q. Genetic and Epigenetic Characteristics of Autosomal Dominant Pseudohypoparathyroidism Type 1B: Case Reports and Literature Review. Horm Metab Res 2021; 53:225-235. [PMID: 33513624 DOI: 10.1055/a-1341-9891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Autosomal dominant pseudohypoparathyroidism 1B (AD-PHP1B) is a rare endocrine and imprinted disorder. The objective of this study is to clarify the imprinted regulation of the guanine nucleotide binding-protein α-stimulating activity polypeptide 1 (GNAS) cluster in the occurrence and development of AD-PHP1B based on animal and clinical patient studies. The methylation-specific multiples ligation-dependent probe amplification (MS-MLPA) was conducted to detect the copy number variation in syntaxin-16 (STX16) gene and methylation status of the GNAS differentially methylated regions (DMRs). Long-range PCR was used to confirm deletion at STX16 gene. In the first family, DNA analysis of the proband and proband's mother revealed an isolated loss of methylation (LOM) at exon A/B and a 3.0 kb STX16 deletion. The patient's healthy grandmother had the 3.0 kb STX16 deletion but no epigenetic abnormality. The patient's healthy maternal aunt showed no genetic or epigenetic abnormality. In the second family, the analysis of long-range PCR revealed the 3.0 kb STX16 deletion for the proband but not her children. In this study, 3.0 kb STX16 deletion causes isolated LOM at exon A/B in two families, which is the most common genetic mutation of AD-PHP1B. The deletion involving NESP55 or AS or genomic rearrangements of GNAS can also result in AD-PHP1B, but it's rare. LOM at exon A/B DMR is prerequisite methylation defect of AD-PHP1B. STX16 and NESP55 directly control the imprinting at exon A/B, while AS controls the imprinting at exon A/B by regulating the transcriptional level of NESP55.
Collapse
Affiliation(s)
- Dandan Luo
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Xiangyu Qi
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Luna Liu
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Yu Su
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Li Fang
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Qingbo Guan
- Department of Endocrinology and Metabolism, Shandong University, Jinan, Shandong, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| |
Collapse
|
10
|
Casella I, Ambrosio C. Prokineticin receptors interact unselectively with several G protein subtypes but bind selectively to β-arrestin 2. Cell Signal 2021; 83:110000. [PMID: 33811988 DOI: 10.1016/j.cellsig.2021.110000] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/29/2021] [Accepted: 03/30/2021] [Indexed: 11/19/2022]
Abstract
Prokineticin 1 (pk1) and prokineticin 2 (pk2) interact with two structurally related G-protein coupled receptors, prokineticin receptor 1 (PKR1) and prokineticin receptor 2 (PKR2). Cellular signalling studies show that the activated receptors can evoke Ca2+-mobilization, pertussis toxin-sensitive ERK phosphorylation, and intracellular cAMP accumulation, which suggests the partecipation of several G protein subtypes, such as Gq/11, Gi/o and Gs. However, direct interactions with these transduction proteins have not been studied yet. Here we measured by bioluminescence resonance energy transfer (BRET) the association of PKR1 and PKR2 with different heterotrimeric Gα proteins in response to pk1 and pk2 activation. Using host-cell lines carrying gene deletions of Gαq/11 or Gαs, and pertussis toxin treatment to abolish the receptor interactions with Gαi/o, we determined that both receptors could couple with comparable efficiency to Gq/11 and Gi/o, but far less efficiently to Gs or other pertussis toxin-insensitive G proteins. We also used BRET methodology to assess the association of prokineticin receptors with β-arrestin isoforms. Fluorescent versions of the isoforms were transfected both in HEK293 cells and in double KO β-arrestin 1/2 mouse fibroblasts, to study receptor interaction with the reconstituted individual β-arrestins without background expression of the endogenous genes. Both receptors formed stable BRET-emitting complexes with β-arrestin 2 but not with β-arrestin 1, indicating strong selectivity for the former. In all the studied transducer interactions and in both receptors, pk2 was more potent than pk1 in promoting receptor binding to transduction proteins.
Collapse
Affiliation(s)
- Ida Casella
- Istituto Superiore di Sanità, National Center for Drug Reserch and Evaluation, Viale Regina Elena, 299, 00161 Rome, Italy.
| | - Caterina Ambrosio
- Istituto Superiore di Sanità, National Center for Drug Reserch and Evaluation, Viale Regina Elena, 299, 00161 Rome, Italy
| |
Collapse
|
11
|
Wang Y, Tian H, Chen X. The Distinct Role of the Extra-Large G Protein ɑ-Subunit XLɑs. Calcif Tissue Int 2020; 107:212-219. [PMID: 32596800 DOI: 10.1007/s00223-020-00714-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 06/17/2020] [Indexed: 02/05/2023]
Abstract
GNAS is one of the most complex gene loci in the human genome and encodes multiple gene products including Gsα, XLαs, NESP55, A/B, and AS transcripts. XLαs, the extra-large G protein ɑ-subunit, is paternally expressed. XLɑs and Gsɑ share the common 2-13 exons with different promoters and first exons. Therefore, XLɑs contains most of the functional domains of Gsα including receptor and effector binding sites. In vitro studies suggest a "Gsɑ"-like function of XLɑs regarding the stimulation of cAMP generation in response to receptor activation with different cellular actions. However, it is unclear whether XLαs has an important physiological function in humans. Pseudopseudohypoparathyroidism (PPHP) and progressive osseous heteroplasia (POH) are caused by paternally inherited mutations of GNAS. Maternal uniparental disomy of chromosome 20 [UPD(20)mat] lacks paternal chromosome 20. Therefore, the phenotypes of these diseases may be secondary to the abnormal functions of XLɑs, at least partly. From the phenotypes of human diseases like PPHP, POH, and UPD(20)mat, as well as some animal models with deficient XLɑs functions, it could be seen that XLɑs is involved in the growth and development of the mammalian fetus, plays a different role in glucose, lipid, and energy metabolism when compared with Gsɑ, and could prevent heterotopic ossification in humans and mice. More in vivo and in vitro studies, especially the development of conditional XLɑs knockout mice, are needed to clarify the physiopathologic roles and related signal pathways of XLɑs.
Collapse
Affiliation(s)
- Yan Wang
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, West China Hospital, Sichuan University, No. 37 Guoxue Xiang, Chengdu, 610041, China
| | - Haoming Tian
- Department of Endocrinology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiang Chen
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, West China Hospital, Sichuan University, No. 37 Guoxue Xiang, Chengdu, 610041, China.
| |
Collapse
|
12
|
Vezzi V, Ambrosio C, Grò MC, Molinari P, Süral G, Costa T, Onaran HO, Cotecchia S. Vasopressin receptor 2 mutations in the nephrogenic syndrome of inappropriate antidiuresis show different mechanisms of constitutive activation for G protein coupled receptors. Sci Rep 2020; 10:9111. [PMID: 32499611 PMCID: PMC7272623 DOI: 10.1038/s41598-020-65996-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/13/2020] [Indexed: 01/14/2023] Open
Abstract
Vasopressin receptor 2 (V2R) mutations causing the nephrogenic syndrome of inappropriate antidiuresis (NSIAD) can generate two constitutively active receptor phenotypes. One type results from residue substitutions in several V2R domains and is sensitive to vaptan inverse agonists. The other is only caused by Arg 137 replacements and is vaptan resistant. We compared constitutive and agonist-driven interactions of the vaptan-sensitive F229V and vaptan-resistant R137C/L V2R mutations with β-arrestin 1, β-arrestin 2, and Gαs, using null fibroblasts reconstituted with individual versions of the ablated transduction protein genes. F229V displayed very high level of constitutive activation for Gs but not for β-arrestins, and enhanced or normal responsiveness to agonists and inverse agonists. In contrast, R137C/L mutants exhibited maximal levels of constitutive activation for βarrestin 2 and Gs, minimal levels for β-arrestin 1, but a sharp decline of ligands sensitivity at all transducer interactions. The enhanced constitutive activity and reduced ligand sensitivity of R137 mutants on cAMP signaling persisted in cells lacking β-arrestins, indicating that these are intrinsic molecular properties of the mutations, not the consequence of altered receptor trafficking. The results suggest that the two groups of NSIAD mutations represent two distinct molecular mechanisms of constitutive activation in GPCRs.
Collapse
Affiliation(s)
- Vanessa Vezzi
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Caterina Ambrosio
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Maria Cristina Grò
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Paola Molinari
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Gökçe Süral
- Ankara University, Faculty of Medicine, Department of Pharmacology, Molecular biology and Technology development unit, Sıhhiye, Ankara, Turkey
| | - Tommaso Costa
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - H Ongun Onaran
- Ankara University, Faculty of Medicine, Department of Pharmacology, Molecular biology and Technology development unit, Sıhhiye, Ankara, Turkey
| | - Susanna Cotecchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy.
| |
Collapse
|
13
|
Chen X, Meng Y, Tang M, Wang Y, Xie Y, Wan S, Tian H, Yu X. A paternally inherited non-sense variant c.424G>T (p.G142*) in the first exon of XLαs in an adult patient with hypophosphatemia and osteopetrosis. Clin Genet 2020; 97:712-722. [PMID: 32157680 DOI: 10.1111/cge.13734] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 02/05/2023]
Abstract
XLαs, the extra-large isoform of alpha-subunit of the stimulatory guanine nucleotide-binding protein (Gsα), is paternally expressed. The significance of XLαs in humans remains largely unknown. Here, we report a patient who presented with increased bone mass, hypophosphatemia, and elevated parathyroid hormone (PTH) levels. His serum calcium was in the lower limit of the normal range. Whole exome sequencing of this subject found a novel non-sense variant c.424G>T (p. G142*) in the first exon of XLαs, which was inherited from his father and transmitted to his daughter. This variant was predicted to exclusively influence the expression of XLαs, while possibly having no significant effects on other gene products of this locus. Ellsworth-Howard test revealed normal renal response to PTH in proband. Human SaOS2 cells transfected with mutant XLαs failed to generate cyclic adenosine monophosphate under PTH stimulation, indicating skeletal resistance to this hormone. This subject showed higher circulating sclerostin, dickkopf1, and osteoprotegerin (OPG) levels, while lower receptor activator of nuclear factor kappa-B ligand/OPG ratio, leading to reduced bone resorption. Our findings indicate that XLαs plays a critical role in bone metabolism and GNAS locus should be considered as a candidate gene for high bone mass.
Collapse
Affiliation(s)
- Xiang Chen
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yang Meng
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Mengjia Tang
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yan Wang
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Ying Xie
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Shan Wan
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Haoming Tian
- Department of Endocrinology, West China Hospital, Sichuan University, Chengdu, China
| | - Xijie Yu
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| |
Collapse
|
14
|
Matthias J, Cui Q, Shumate LT, Plagge A, He Q, Bastepe M. Extra-Large Gα Protein (XLαs) Deficiency Causes Severe Adenine-Induced Renal Injury with Massive FGF23 Elevation. Endocrinology 2020; 161:5638044. [PMID: 31758181 PMCID: PMC6986553 DOI: 10.1210/endocr/bqz025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/22/2019] [Indexed: 11/19/2022]
Abstract
Fibroblast growth factor-23 (FGF23) is critical for phosphate and vitamin D homeostasis. Cellular and molecular mechanisms underlying FGF23 production remain poorly defined. The extra-large Gα subunit (XLαs) is a variant of the stimulatory G protein alpha-subunit (Gsα), which mediates the stimulatory action of parathyroid hormone in skeletal FGF23 production. XLαs ablation causes diminished FGF23 levels in early postnatal mice. Herein we found that plasma FGF23 levels were comparable in adult XLαs knockout (XLKO) and wild-type littermates. Upon adenine-rich diet-induced renal injury, a model of chronic kidney disease, both mice showed increased levels of plasma FGF23. Unexpectedly, XLKO mice had markedly higher FGF23 levels than WT mice, with higher blood urea nitrogen and more severe tubulopathy. FGF23 mRNA levels increased substantially in bone and bone marrow in both genotypes; however, the levels in bone were markedly higher than in bone marrow. In XLKO mice, a positive linear correlation was observed between plasma FGF23 and bone, but not bone marrow, FGF23 mRNA levels, suggesting that bone, rather than bone marrow, is an important contributor to severely elevated FGF23 levels in this model. Upon folic acid injection, a model of acute kidney injury, XLKO and WT mice exhibited similar degrees of tubulopathy; however, plasma phosphate and FGF23 elevations were modestly blunted in XLKO males, but not in females, compared to WT counterparts. Our findings suggest that XLαs ablation does not substantially alter FGF23 production in adult mice but increases susceptibility to adenine-induced kidney injury, causing severe FGF23 elevations in plasma and bone.
Collapse
Affiliation(s)
- Julia Matthias
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Qiuxia Cui
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Lauren T Shumate
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Antonius Plagge
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Qing He
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
- Correspondence: Murat Bastepe, MD, PhD, 50 Blossom St. Thier 10 Boston, MA 02114, USA. E-mail: and Qing He, PhD 50 Blossom St. Thier 10 Boston, Massachusetts 02114, USA. E-mail:
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
- Correspondence: Murat Bastepe, MD, PhD, 50 Blossom St. Thier 10 Boston, MA 02114, USA. E-mail: and Qing He, PhD 50 Blossom St. Thier 10 Boston, Massachusetts 02114, USA. E-mail:
| |
Collapse
|
15
|
He Q, Shumate LT, Matthias J, Aydin C, Wein MN, Spatz JM, Goetz R, Mohammadi M, Plagge A, Divieti Pajevic P, Bastepe M. A G protein-coupled, IP3/protein kinase C pathway controlling the synthesis of phosphaturic hormone FGF23. JCI Insight 2019; 4:125007. [PMID: 31484825 PMCID: PMC6777913 DOI: 10.1172/jci.insight.125007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 08/01/2019] [Indexed: 12/23/2022] Open
Abstract
Dysregulated actions of bone-derived phosphaturic hormone fibroblast growth factor 23 (FGF23) result in several inherited diseases, such as X-linked hypophosphatemia (XLH), and contribute substantially to the mortality in kidney failure. Mechanisms governing FGF23 production are poorly defined. We herein found that ablation of the Gq/11α-like, extralarge Gα subunit (XLαs), a product of GNAS, exhibits FGF23 deficiency and hyperphosphatemia in early postnatal mice (XLKO). FGF23 elevation in response to parathyroid hormone, a stimulator of FGF23 production via cAMP, was intact in XLKO mice, while skeletal levels of protein kinase C isoforms α and δ (PKCα and PKCδ) were diminished. XLαs ablation in osteocyte-like Ocy454 cells suppressed the levels of FGF23 mRNA, inositol 1,4,5-trisphosphate (IP3), and PKCα/PKCδ proteins. PKC activation in vivo via injecting phorbol myristate acetate (PMA) or by constitutively active Gqα-Q209L in osteocytes and osteoblasts promoted FGF23 production. Molecular studies showed that the PKC activation-induced FGF23 elevation was dependent on MAPK signaling. The baseline PKC activity was elevated in bones of Hyp mice, a model of XLH. XLαs ablation significantly, but modestly, reduced serum FGF23 and elevated serum phosphate in Hyp mice. These findings reveal a potentially hitherto-unknown mechanism of FGF23 synthesis involving a G protein-coupled IP3/PKC pathway, which may be targeted to fine-tune FGF23 levels.
Collapse
Affiliation(s)
- Qing He
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Lauren T. Shumate
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Julia Matthias
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Cumhur Aydin
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Department of Endodontics, Gulhane Faculty of Dentistry, University of Health Sciences, Ankara, Turkey
| | - Marc N. Wein
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jordan M. Spatz
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Regina Goetz
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, New York, USA
| | - Moosa Mohammadi
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, New York, USA
| | - Antonius Plagge
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Paola Divieti Pajevic
- Department of Molecular & Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
16
|
Biebermann H, Kleinau G, Schnabel D, Bockenhauer D, Wilson LC, Tully I, Kiff S, Scheerer P, Reyes M, Paisdzior S, Gregory JW, Allgrove J, Krude H, Mannstadt M, Gardella TJ, Dattani M, Jüppner H, Grüters A. A New Multisystem Disorder Caused by the Gαs Mutation p.F376V. J Clin Endocrinol Metab 2019; 104:1079-1089. [PMID: 30312418 PMCID: PMC6380466 DOI: 10.1210/jc.2018-01250] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/08/2018] [Indexed: 11/19/2022]
Abstract
CONTEXT The α subunit of the stimulatory G protein (Gαs) links numerous receptors to adenylyl cyclase. Gαs, encoded by GNAS, is expressed predominantly from the maternal allele in certain tissues. Thus, maternal heterozygous loss-of-function mutations cause hormonal resistance, as in pseudohypoparathyroidism type Ia, whereas somatic gain-of-function mutations cause hormone-independent endocrine stimulation, as in McCune-Albright syndrome. OBJECTIVE We report two unrelated boys presenting with a new combination of clinical findings that suggest both gain and loss of Gαs function. DESIGN AND SETTING Clinical features were studied and sequencing of GNAS was performed. Signaling capacities of wild-type and mutant Gαs were determined in the presence of different G protein-coupled receptors (GPCRs) under basal and agonist-stimulated conditions. RESULTS Both unrelated patients presented with unexplained hyponatremia in infancy, followed by severe early onset gonadotrophin-independent precocious puberty and skeletal abnormalities. An identical heterozygous de novo variant (c.1136T>G; p.F376V) was found on the maternal GNAS allele in both patients; this resulted in a clinical phenotype that differed from known Gαs-related diseases and suggested gain of function at the vasopressin 2 receptor (V2R) and lutropin/choriogonadotropin receptor (LHCGR), yet increased serum PTH concentrations indicative of impaired proximal tubular PTH1 receptor (PTH1R) function. In vitro studies demonstrated that Gαs-F376V enhanced ligand-independent signaling at the PTH1R, LHCGR, and V2R and, at the same time, blunted ligand-dependent responses. Structural homology modeling suggested mutation-induced modifications at the C-terminal α5 helix of Gαs that are relevant for interaction with GPCRs and signal transduction. CONCLUSIONS The Gαs p.F376V mutation causes a previously unrecognized multisystem disorder.
Collapse
Affiliation(s)
- Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dirk Schnabel
- Department for Pediatric Endocrinology and Diabetology, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Center for Chronically Sick Children, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Detlef Bockenhauer
- UCL Centre for Nephrology, London, United Kingdom
- Great Ormond Street Hospital for Children, Renal Unit, London, United Kingdom
| | - Louise C Wilson
- Department of Clinical Genetics, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Ian Tully
- Department of Clinical Genetics, University Hospital of Wales, Cardiff, United Kingdom
| | - Sarah Kiff
- Department of Pediatric Endocrinology, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Patrick Scheerer
- Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Sarah Paisdzior
- Institute of Experimental Pediatric Endocrinology, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - John W Gregory
- Division of Population Medicine, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Jeremy Allgrove
- Department of Pediatric Endocrinology, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Thomas J Gardella
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Mehul Dattani
- Department of Pediatric Endocrinology, Great Ormond Street Hospital for Children, London, United Kingdom
- Section of Genetics and Epigenetics in Health and Disease, Genetics and Genomic Medicine Programme, UCL GOS Institute of Child Health, London, United Kingdom
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Annette Grüters
- Department for Pediatric Endocrinology and Diabetology, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
- University Hospital Heidelberg, Heidelberg, Germany
- Correspondence and Reprint Requests: Annette Grüters, PhD, Charité-Universitätsmedizin, Department for Pediatric Endocrinology and Diabetes, Mittelallee 8, 13353 Berlin, Germany. E-mail:
| |
Collapse
|
17
|
Abstract
GNAS is a complex imprinted gene encoding the alpha-subunit of the stimulatory heterotrimeric G protein (Gsα). GNAS gives rise to additional gene products that exhibit exclusively maternal or paternal expression, such as XLαs, a large variant of Gsα that shows exclusively paternal expression and is partly identical to the latter. Gsα itself is expressed biallelically in most tissues, although the expression occurs predominantly from the maternal allele in a small set of tissues, such as renal proximal tubules. Inactivating mutations in Gsα-coding GNAS exons are responsible for Albright's hereditary osteodystrophy (AHO), which refers to a constellation of physical and developmental disorders including obesity, short stature, brachydactyly, cognitive impairment, and heterotopic ossification. Patients with Gsα mutations can present with AHO in the presence or absence of end-organ resistance to multiple hormones including parathyroid hormone. Maternal Gsα mutations lead to AHO with hormone resistance (i.e. pseudohypoparathyroidism type-Ia), whereas paternal mutations cause AHO alone (i.e. pseudo-pseudohypoparathyroidism). Heterotopic ossification associated with AHO develops through intramembranous bone formation and is limited to dermis and subcutis. In rare cases carrying Gsα mutations, however, ossifications progress into deep connective tissue and skeletal muscle, a disorder termed progressive osseous heteroplasia (POH). Here I briefly review the genetic, clinical, and molecular aspects of these disorders caused by inactivating GNAS mutations, with particular emphasis on heterotopic ossification.
Collapse
Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, United States.
| |
Collapse
|
18
|
Salemi P, Skalamera Olson JM, Dickson LE, Germain-Lee EL. Ossifications in Albright Hereditary Osteodystrophy: Role of Genotype, Inheritance, Sex, Age, Hormonal Status, and BMI. J Clin Endocrinol Metab 2018; 103:158-168. [PMID: 29059381 PMCID: PMC5761497 DOI: 10.1210/jc.2017-00860] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 10/16/2017] [Indexed: 12/14/2022]
Abstract
CONTEXT Albright hereditary osteodystrophy (AHO) is caused by heterozygous inactivating mutations in GNAS. Depending on the parental origin of the mutated allele, patients develop either pseudohypoparathyroidism type 1A (PHP1A), with multihormone resistance and severe obesity, or pseudopseudohypoparathyroidism (PPHP), without hormonal abnormalities or marked obesity. Subcutaneous ossifications (SCOs) are a source of substantial morbidity in both PHP1A and PPHP. OBJECTIVE This study investigated the previously undetermined prevalence of SCO formation in PHP1A vs PPHP as well as possible correlations with genotype, sex, age, hormonal resistance, and body mass index (BMI). DESIGN This study evaluated patients with AHO for SCOs by physical examination performed by one consistent physician over 16 years. SETTING Albright Clinic, Kennedy Krieger Institute; Institute for Clinical and Translational Research, Johns Hopkins Hospital; Albright Center, Connecticut Children's Medical Center. PATIENTS We evaluated 67 patients with AHO (49 with PHP1A, 18 with PPHP) with documented mutations in GNAS. MAIN OUTCOME MEASURES Relationships of SCOs to genotype, sex, age, hormonal resistance, and BMI. RESULTS Forty-seven of 67 participants (70.1%) had SCOs. Patients with PHP1A and PPHP had similar prevalences and degrees of ossification formation. Patients with frameshift and nonsense mutations had much more extensive SCOs than those with missense mutations. Males were affected more than females. There was no correlation with hormonal status or BMI. CONCLUSIONS There is a similar prevalence of SCOs in PHP1A and PPHP, and the extent of SCO formation correlates with the severity of the mutation. Males are affected more extensively than females, and the SCOs tend to worsen with age.
Collapse
Affiliation(s)
- Parissa Salemi
- Department of Pediatrics, Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - Lauren E Dickson
- Albright Center and Center for Rare Bone Disorders, Division of Pediatric Endocrinology & Diabetes, Connecticut Children's Medical Center, Farmington, Connecticut
| | - Emily L Germain-Lee
- Department of Pediatrics, Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Albright Clinic, Kennedy Krieger Institute, Baltimore, Maryland
- Albright Center and Center for Rare Bone Disorders, Division of Pediatric Endocrinology & Diabetes, Connecticut Children's Medical Center, Farmington, Connecticut
- Department of Pediatrics, University of Connecticut School of Medicine, Farmington, Connecticut
| |
Collapse
|
19
|
Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo. Proc Natl Acad Sci U S A 2017; 114:E9559-E9568. [PMID: 29078380 DOI: 10.1073/pnas.1712670114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Alterations in the activity/levels of the extralarge G protein α-subunit (XLαs) are implicated in various human disorders, such as perinatal growth retardation. Encoded by GNAS, XLαs is partly identical to the α-subunit of the stimulatory G protein (Gsα), but the cellular actions of XLαs remain poorly defined. Following an initial proteomic screen, we identified sorting nexin-9 (SNX9) and dynamins, key components of clathrin-mediated endocytosis, as binding partners of XLαs. Overexpression of XLαs in HEK293 cells inhibited internalization of transferrin, a process that depends on clathrin-mediated endocytosis, while its ablation by CRISPR/Cas9 in an osteocyte-like cell line (Ocy454) enhanced it. Similarly, primary cardiomyocytes derived from XLαs knockout (XLKO) pups showed enhanced transferrin internalization. Early postnatal XLKO mice showed a significantly higher degree of cardiac iron uptake than wild-type littermates following iron dextran injection. In XLKO neonates, iron and ferritin levels were elevated in heart and skeletal muscle, where XLαs is normally expressed abundantly. XLKO heart and skeletal muscle, as well as XLKO Ocy454 cells, showed elevated SNX9 protein levels, and siRNA-mediated knockdown of SNX9 in XLKO Ocy454 cells prevented enhanced transferrin internalization. In transfected cells, XLαs also inhibited internalization of the parathyroid hormone and type 2 vasopressin receptors. Internalization of transferrin and these G protein-coupled receptors was also inhibited in cells expressing an XLαs mutant missing the Gα portion, but not Gsα or an N-terminally truncated XLαs mutant unable to interact with SNX9 or dynamin. Thus, XLαs restricts clathrin-mediated endocytosis and plays a critical role in iron/transferrin uptake in vivo.
Collapse
|
20
|
Usardi A, Mamoune A, Nattes E, Carel JC, Rothenbuhler A, Linglart A. Progressive Development of PTH Resistance in Patients With Inactivating Mutations on the Maternal Allele of GNAS. J Clin Endocrinol Metab 2017; 102:1844-1850. [PMID: 28323910 DOI: 10.1210/jc.2016-3544] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 02/16/2017] [Indexed: 01/04/2023]
Abstract
CONTEXT Parathormone (PTH) resistance is characterized by hypocalcaemia, hyperphosphatemia, and elevated PTH in the absence of vitamin D deficiency. Pseudohypoparathyroidism type 1A [PHP1A, or inactivating parathormone (PTH)/PTHrp signaling disorder 2, according to the new classification (iPPSD2)], is caused by mutations in the maternal GNAS allele. OBJECTIVE To assess PTH resistance over time in 20 patients affected by iPPSD2 (PHP1A), diagnosed because of family history, ectopic ossification, or short stature, and carrying a GNAS mutation. METHODS We gathered retrospective data for calcium, phosphate, thyrotropin (TSH), and PTH levels at regular intervals. PTH infusion testing (teriparatide) was performed in 1 patient. RESULTS Patients were diagnosed at a mean age of 3.9 years and had a mean follow-up of 2 years. TSH resistance was already present at diagnosis in all patients (TSH, 13.3 ± 9.0 mIU/L). Over time, PTH levels increased (179 to 306 pg/mL; P < 0.05), and calcium levels decreased (2.31 to 2.21 mmol/L; P < 0.05), but phosphate levels did not decrease with age as expected for healthy individuals. One patient born with ectopic ossifications showed an increase in cyclic adenosine monophosphate upon PTH infusion, similar to that of controls, at 7 months of age, but an impaired response at 4 years of age. CONCLUSIONS In patients with iPPSD2 (PHP1A), PTH resistance and hypocalcemia develop over time. These findings highlight the importance of screening for maternal GNAS mutations in the presence of ectopic ossifications or family history, even in the absence of PTH resistance and hypocalcemia. The follow-up of these patients should include regular assessments of calcium, phosphate, and PTH levels.
Collapse
Affiliation(s)
- Alessia Usardi
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
| | - Asmaa Mamoune
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
| | - Elodie Nattes
- Department of Pediatric Endocrinology and Diabetology, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
| | - Jean-Claude Carel
- Department of Pediatric Endocrinology, AP-HP, Robert Debré Paris-Nord Hospital, 75019 Paris, France
| | - Anya Rothenbuhler
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
- Department of Pediatric Endocrinology and Diabetology, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
| | - Agnès Linglart
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Platform of Expertise Paris-Sud for Rare Diseases and Filière OSCAR, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
- Department of Pediatric Endocrinology and Diabetology, AP-HP, Bicêtre Paris-Sud Hospital, 94270 Le Kremlin-Bicêtre, France
- INSERM U1169, Bicêtre Paris-Sud Hospital and Université Paris-Saclay, 94270 Le Kremlin Bicêtre, France
| |
Collapse
|
21
|
Bastepe M, Turan S, He Q. Heterotrimeric G proteins in the control of parathyroid hormone actions. J Mol Endocrinol 2017; 58:R203-R224. [PMID: 28363951 PMCID: PMC5650080 DOI: 10.1530/jme-16-0221] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 02/17/2017] [Indexed: 12/17/2022]
Abstract
Parathyroid hormone (PTH) is a key regulator of skeletal physiology and calcium and phosphate homeostasis. It acts on bone and kidney to stimulate bone turnover, increase the circulating levels of 1,25 dihydroxyvitamin D and calcium and inhibit the reabsorption of phosphate from the glomerular filtrate. Dysregulated PTH actions contribute to or are the cause of several endocrine disorders. This calciotropic hormone exerts its actions via binding to the PTH/PTH-related peptide receptor (PTH1R), which couples to multiple heterotrimeric G proteins, including Gs and Gq/11 Genetic mutations affecting the activity or expression of the alpha-subunit of Gs, encoded by the GNAS complex locus, are responsible for several human diseases for which the clinical findings result, at least partly, from aberrant PTH signaling. Here, we review the bone and renal actions of PTH with respect to the different signaling pathways downstream of these G proteins, as well as the disorders caused by GNAS mutations.
Collapse
Affiliation(s)
- Murat Bastepe
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Serap Turan
- Department of Pediatric EndocrinologyMarmara University School of Medicine, Istanbul, Turkey
| | - Qing He
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
22
|
Elli FM, Boldrin V, Pirelli A, Spada A, Mantovani G. The Complex GNAS Imprinted Locus and Mesenchymal Stem Cells Differentiation. Horm Metab Res 2017; 49:250-258. [PMID: 27756094 DOI: 10.1055/s-0042-115305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
All tissues and organs derive from stem cells, which are undifferentiated cells able to differentiate into specialized cells and self-renewal. In mammals, there are embryonic stem cells that generate germ layers, and adult stem cells, which act as a repair system for the body and maintain the normal turnover of regenerative organs. Mesenchymal stem cells (MSCs) are nonhematopoietic adult multipotent cells, which reside in virtually all postnatal organs and tissues, and, under appropriate in vitro conditions, are capable to differentiate into osteogenic, adipogenic, chondrogenic, myogenic, and neurogenic lineages. Their commitment and differentiation depend on several interacting signaling pathways and transcription factors. Most GNAS-based disorders have the common feature of episodic de novo formation of islands of extraskeletal, qualitatively normal, bone in skin and subcutaneous fat. The tissue distribution of these lesions suggests that pathogenesis involves abnormal differentiation of MSCs and/or more committed precursor cells that are present in subcutaneous tissues. Data coming from transgenic mice support the concept that GNAS is a key factor in the regulation of lineage switching between osteoblast and adipocyte fates, and that its role may be to prevent bone formation in tissues where bone should not form. Despite the growing knowledge about the process of heterotopic ossification in rare genetic disorders, the pathophysiological mechanisms by which alterations of cAMP signaling lead to ectopic bone formation in the context of mesenchymal tissues is not fully understood.
Collapse
Affiliation(s)
- F M Elli
- Department of Clinical Sciences and Community Health, Endocrinology and Diabetology Unit, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - V Boldrin
- Department of Clinical Sciences and Community Health, Endocrinology and Diabetology Unit, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - A Pirelli
- Department of Clinical Sciences and Community Health, Endocrinology and Diabetology Unit, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - A Spada
- Department of Clinical Sciences and Community Health, Endocrinology and Diabetology Unit, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - G Mantovani
- Department of Clinical Sciences and Community Health, Endocrinology and Diabetology Unit, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| |
Collapse
|
23
|
Tafaj O, Jüppner H. Pseudohypoparathyroidism: one gene, several syndromes. J Endocrinol Invest 2017; 40:347-356. [PMID: 27995443 DOI: 10.1007/s40618-016-0588-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 11/25/2016] [Indexed: 01/04/2023]
Abstract
Pseudohypoparathyroidism (PHP) and pseudopseudohypoparathyroidism (PPHP) are caused by mutations and/or epigenetic changes at the complex GNAS locus on chromosome 20q13.3 that undergoes parent-specific methylation changes at several sites. GNAS encodes the alpha-subunit of the stimulatory G protein (Gsα) and several splice variants thereof. Heterozygous inactivating mutations involving the maternal GNAS exons 1-13 cause PHP type Ia (PHP1A). Because of much reduced paternal Gsα expression in certain tissues, such as the proximal renal tubules, thyroid, and pituitary, there is little or no Gsα protein in the presence of maternal GNAS mutations, thus leading to PTH-resistant hypocalcemia and hyperphosphatemia. When located on the paternal allele, the same or similar GNAS mutations are the cause of PPHP. Besides biochemical abnormalities, patients affected by PHP1A show developmental abnormalities, referred to as Albrights hereditary osteodystrophy (AHO). Some, but not all of these AHO features are encountered also in patients affected by PPHP, who typically show no laboratory abnormalities. Autosomal dominant PHP type Ib (AD-PHP1B) is caused by heterozygous maternal deletions within GNAS or STX16, which are associated with loss-of-methylation (LOM) at exon A/B alone or at all maternally methylated GNAS exons. LOM at exon A/B and the resulting biallelic expression of A/B transcripts reduces Gsα expression, thus leading to hormonal resistance. Epigenetic changes at all differentially methylated GNAS regions are also observed in sporadic PHP1B, the most frequent disease variant, which remains unresolved at the molecular level, except for rare cases with paternal uniparental isodisomy or heterodisomy of chromosome 20q (patUPD20q).
Collapse
Affiliation(s)
- O Tafaj
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Thier 10, 50 Blossom Street, Boston, MA, 02114, USA
| | - H Jüppner
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Thier 10, 50 Blossom Street, Boston, MA, 02114, USA.
- Pediatric Nephrology Unit, Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
24
|
Systematic errors in detecting biased agonism: Analysis of current methods and development of a new model-free approach. Sci Rep 2017; 7:44247. [PMID: 28290478 PMCID: PMC5349545 DOI: 10.1038/srep44247] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/06/2017] [Indexed: 11/08/2022] Open
Abstract
Discovering biased agonists requires a method that can reliably distinguish the bias in signalling due to unbalanced activation of diverse transduction proteins from that of differential amplification inherent to the system being studied, which invariably results from the non-linear nature of biological signalling networks and their measurement. We have systematically compared the performance of seven methods of bias diagnostics, all of which are based on the analysis of concentration-response curves of ligands according to classical receptor theory. We computed bias factors for a number of β-adrenergic agonists by comparing BRET assays of receptor-transducer interactions with Gs, Gi and arrestin. Using the same ligands, we also compared responses at signalling steps originated from the same receptor-transducer interaction, among which no biased efficacy is theoretically possible. In either case, we found a high level of false positive results and a general lack of correlation among methods. Altogether this analysis shows that all tested methods, including some of the most widely used in the literature, fail to distinguish true ligand bias from "system bias" with confidence. We also propose two novel semi quantitative methods of bias diagnostics that appear to be more robust and reliable than currently available strategies.
Collapse
|
25
|
Jean-Alphonse FG, Wehbi VL, Chen J, Noda M, Taboas JM, Xiao K, Vilardaga JP. β 2-adrenergic receptor control of endosomal PTH receptor signaling via Gβγ. Nat Chem Biol 2016; 13:259-261. [PMID: 28024151 DOI: 10.1038/nchembio.2267] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 10/18/2016] [Indexed: 11/09/2022]
Abstract
Cells express several G-protein-coupled receptors (GPCRs) at their surfaces, transmitting simultaneous extracellular hormonal and chemical signals into cells. A comprehensive understanding of mechanisms underlying the integrated signaling response induced by distinct GPCRs is thus required. Here we found that the β2-adrenergic receptor, which induces a short cAMP response, prolongs nuclear cAMP and protein kinase A (PKA) activation by promoting endosomal cAMP production in parathyroid hormone (PTH) receptor signaling through the stimulatory action of G protein Gβγ subunits on adenylate cyclase type 2.
Collapse
Affiliation(s)
- Frédéric G Jean-Alphonse
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Vanessa L Wehbi
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jingming Chen
- Department of Biomedical Engineering, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Masaki Noda
- Department of Molecular Pharmacology, Medical Research Institute Tokyo Medical and Dental University, Bunkyo-Ku, Tokyo, Japan
| | - Juan M Taboas
- Department of Biomedical Engineering, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.,McGowan Institute of Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Kunhong Xiao
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
26
|
A Novel T55A Variant of Gs α Associated with Impaired cAMP Production, Bone Fragility, and Osteolysis. Case Rep Endocrinol 2016; 2016:2691385. [PMID: 27579188 PMCID: PMC4992514 DOI: 10.1155/2016/2691385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 06/03/2016] [Accepted: 07/03/2016] [Indexed: 01/08/2023] Open
Abstract
G-protein coupled receptors (GPCRs) mediate a wide spectrum of biological activities. The GNAS complex locus encodes the stimulatory alpha subunit of the guanine nucleotide binding protein (Gsα) and regulates production of the second messenger cyclic AMP (cAMP). Loss-of-function GNAS mutations classically lead to Albright's Hereditary Osteodystrophy (AHO) and pseudohypoparathyroidism, often with significant effects on bone formation and mineral metabolism. We present the case of a child who exhibits clinical features of osteolysis, multiple childhood fractures, and neonatal SIADH. Exome sequencing revealed a novel de novo heterozygous missense mutation of GNAS (c.163A<G, p.T55A) affecting the p-loop of the catalytic Gsα GTPase domain. In order to further assess whether this unique mutation resulted in a gain or loss of function of Gsα, we introduced the mutation into a rat GNAS plasmid and performed functional studies to assess the level of cAMP activity associated with this mutation. We identified a 64% decrease in isoproterenol-induced cAMP production in vitro, compared to wild type, consistent with loss of Gsα activity. Despite a significant decrease in isoproterenol-induced cAMP production in vitro, this mutation did not produce a classical AHO phenotype in our patient; however, it may account for her presentation with childhood fractures and osteolysis.
Collapse
|
27
|
Zhang W, Qu X, Chen B, Snyder M, Wang M, Li B, Tang Y, Chen H, Zhu W, Zhan L, Yin N, Li D, Xie L, Liu Y, Zhang JJ, Fu XY, Rubart M, Song LS, Huang XY, Shou W. Critical Roles of STAT3 in β-Adrenergic Functions in the Heart. Circulation 2016; 133:48-61. [PMID: 26628621 PMCID: PMC4698100 DOI: 10.1161/circulationaha.115.017472] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 10/02/2015] [Indexed: 01/08/2023]
Abstract
BACKGROUND β-Adrenergic receptors (βARs) play paradoxical roles in the heart. On one hand, βARs augment cardiac performance to fulfill the physiological demands, but on the other hand, prolonged activations of βARs exert deleterious effects that result in heart failure. The signal transducer and activator of transcription 3 (STAT3) plays a dynamic role in integrating multiple cytokine signaling pathways in a number of tissues. Altered activation of STAT3 has been observed in failing hearts in both human patients and animal models. Our objective is to determine the potential regulatory roles of STAT3 in cardiac βAR-mediated signaling and function. METHODS AND RESULTS We observed that STAT3 can be directly activated in cardiomyocytes by β-adrenergic agonists. To follow up this finding, we analyzed βAR function in cardiomyocyte-restricted STAT3 knockouts and discovered that the conditional loss of STAT3 in cardiomyocytes markedly reduced the cardiac contractile response to acute βAR stimulation, and caused disengagement of calcium coupling and muscle contraction. Under chronic β-adrenergic stimulation, Stat3cKO hearts exhibited pronounced cardiomyocyte hypertrophy, cell death, and subsequent cardiac fibrosis. Biochemical and genetic data supported that Gαs and Src kinases are required for βAR-mediated activation of STAT3. Finally, we demonstrated that STAT3 transcriptionally regulates several key components of βAR pathway, including β1AR, protein kinase A, and T-type Ca(2+) channels. CONCLUSIONS Our data demonstrate for the first time that STAT3 has a fundamental role in βAR signaling and functions in the heart. STAT3 serves as a critical transcriptional regulator for βAR-mediated cardiac stress adaption, pathological remodeling, and heart failure.
Collapse
Affiliation(s)
- Wenjun Zhang
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.).
| | - Xiuxia Qu
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Biyi Chen
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Marylynn Snyder
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Meijing Wang
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Baiyan Li
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Yue Tang
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Hanying Chen
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Wuqiang Zhu
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Li Zhan
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Ni Yin
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Deqiang Li
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Li Xie
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Ying Liu
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - J Jillian Zhang
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Xin-Yuan Fu
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Michael Rubart
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Long-Sheng Song
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Xin-Yun Huang
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.)
| | - Weinian Shou
- From State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (W. Zhang, X.Q., Y.T., W.S.); Riley Heart Research Center, Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indianapolis, IN (W. Zhang, B.L., H.C., W. Zhu, L.Z., N.Y., D.L., L.X., Y.L., M.R., W.S.); Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City (B.C., L.-S.S.); Department of Physiology and Biophysics, Cornell University Weill Medical College, New York, NY (M.S., J.J.Z., X.-Y.H.); Department of Surgery, Indiana University School of Medicine, Indianapolis (M.W.); Department of Pharmacology, Harbin Medical University, Harbin, China (B.L.); Department of Heart Surgery, Xiangya 2nd Hospital, Central South University, Changsha, China (N.Y., L.X.); and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis (X.-Y.F.).
| |
Collapse
|
28
|
He Q, Zhu Y, Corbin BA, Plagge A, Bastepe M. The G protein α subunit variant XLαs promotes inositol 1,4,5-trisphosphate signaling and mediates the renal actions of parathyroid hormone in vivo. Sci Signal 2015; 8:ra84. [PMID: 26307011 DOI: 10.1126/scisignal.aaa9953] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
GNAS, which encodes the stimulatory G protein (heterotrimeric guanine nucleotide-binding protein) α subunit (Gαs), also encodes a large variant of Gαs termed extra-large α subunit (XLαs), and alterations in XLαs abundance or activity are implicated in various human disorders. Although XLαs, like Gαs, stimulates generation of the second messenger cyclic adenosine monophosphate (cAMP), evidence suggests that XLαs and Gαs have opposing effects in vivo. We investigated the role of XLαs in mediating signaling by parathyroid hormone (PTH), which activates a G protein-coupled receptor (GPCR) that stimulates both Gαs and Gαq/11 in renal proximal tubules to maintain phosphate and vitamin D homeostasis. At postnatal day 2 (P2), XLαs knockout (XLKO) mice exhibited hyperphosphatemia, hypocalcemia, and increased serum concentrations of PTH and 1,25-dihydroxyvitamin D. The ability of PTH to reduce serum phosphate concentrations was impaired, and the abundance of the sodium phosphate cotransporter Npt2a in renal brush border membranes was reduced in XLKO mice, whereas PTH-induced cAMP excretion in the urine was modestly increased. Basal and PTH-stimulated production of inositol 1,4,5-trisphosphate (IP3), which is the second messenger produced by Gαq/11 signaling, was repressed in renal proximal tubules from XLKO mice. Crossing of XLKO mice with mice overexpressing XLαs specifically in renal proximal tubules rescued the phenotype of the XLKO mice. Overexpression of XLαs in HEK 293 cells enhanced IP3 generation in unstimulated cells and in cells stimulated with PTH or thrombin, which acts through a Gq/11-coupled receptor. Together, our findings suggest that XLαs enhances Gq/11 signaling to mediate the renal actions of PTH during early postnatal development.
Collapse
Affiliation(s)
- Qing He
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Yan Zhu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Braden A Corbin
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Antonius Plagge
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine University of Liverpool, Liverpool L69 3BX, UK
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
| |
Collapse
|
29
|
Brust TF, Conley JM, Watts VJ. Gα(i/o)-coupled receptor-mediated sensitization of adenylyl cyclase: 40 years later. Eur J Pharmacol 2015; 763:223-32. [PMID: 25981304 DOI: 10.1016/j.ejphar.2015.05.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/02/2015] [Accepted: 05/11/2015] [Indexed: 12/20/2022]
Abstract
Heterologous sensitization of adenylyl cyclase (also referred to as superactivation, sensitization, or supersensitization of adenylyl cyclase) is a cellular adaptive response first described 40 years ago in the laboratory of Dr. Marshall Nirenberg. This apparently paradoxical cellular response occurs following persistent activation of Gαi/o-coupled receptors and causes marked enhancement in the activity of adenylyl cyclases, thereby increasing cAMP production. Since our last review in 2005, significant progress in the field has led to a better understanding of the relevance of, and the cellular biochemical processes that occur during the development and expression of heterologous sensitization. In this review we will discuss the recent advancements in the field and the mechanistic hypotheses on heterologous sensitization.
Collapse
Affiliation(s)
- Tarsis F Brust
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Jason M Conley
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Val J Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA.
| |
Collapse
|
30
|
Huang J, Sun Y, Zhang JJ, Huang XY. Pivotal role of extended linker 2 in the activation of Gα by G protein-coupled receptor. J Biol Chem 2014; 290:272-83. [PMID: 25414258 DOI: 10.1074/jbc.m114.608661] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) relay extracellular signals mainly to heterotrimeric G-proteins (Gαβγ) and they are the most successful drug targets. The mechanisms of G-protein activation by GPCRs are not well understood. Previous studies have revealed a signal relay route from a GPCR via the C-terminal α5-helix of Gα to the guanine nucleotide-binding pocket. Recent structural and biophysical studies uncover a role for the opening or rotating of the α-helical domain of Gα during the activation of Gα by a GPCR. Here we show that β-adrenergic receptors activate eight Gαs mutant proteins (from a screen of 66 Gαs mutants) that are unable to bind Gβγ subunits in cells. Five of these eight mutants are in the αF/Linker 2/β2 hinge region (extended Linker 2) that connects the Ras-like GTPase domain and the α-helical domain of Gαs. This extended Linker 2 is the target site of a natural product inhibitor of Gq. Our data show that the extended Linker 2 is critical for Gα activation by GPCRs. We propose that a GPCR via its intracellular loop 2 directly interacts with the β2/β3 loop of Gα to communicate to Linker 2, resulting in the opening and closing of the α-helical domain and the release of GDP during G-protein activation.
Collapse
Affiliation(s)
- Jianyun Huang
- From the Department of Physiology, Cornell University Weill Medical College, New York, New York 10065
| | - Yutong Sun
- From the Department of Physiology, Cornell University Weill Medical College, New York, New York 10065
| | - J Jillian Zhang
- From the Department of Physiology, Cornell University Weill Medical College, New York, New York 10065
| | - Xin-Yun Huang
- From the Department of Physiology, Cornell University Weill Medical College, New York, New York 10065
| |
Collapse
|
31
|
Mutations in pseudohypoparathyroidism 1a and pseudopseudohypoparathyroidism in ethnic Chinese. PLoS One 2014; 9:e90640. [PMID: 24651309 PMCID: PMC3961212 DOI: 10.1371/journal.pone.0090640] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 02/03/2014] [Indexed: 11/30/2022] Open
Abstract
An inactivating mutation in the GNAS gene causes either pseudohypoparathyroidism 1a (PHP1A) when it is maternally inherited or pseudopseudohypoparathyroidism (PPHP) when it is paternally inherited. We investigated clinical manifestations and mutations of the GNAS gene in ethnic Chinese patients with PHP1A or PPHP. Seven patients from 5 families including 4 girls and 2 boys with PHP1A and 1 girl with PPHP were studied. All PHP1A patients had mental retardation. They were treated with calcitriol and CaCO3 with regular monitoring of serum Ca levels, urinary Ca/Cr ratios, and renal sonography. Among them, 5 patients also had primary hypothyroidism suggesting TSH resistance. One female patient had a renal stone which was treated with extracorporeal shockwave lithotripsy. She had an increased urinary Ca/Cr ratio of 0.481 mg/mg when the stone was detected. We detected mutations using PCR and sequencing as well as analysed a splice acceptor site mutation using RT-PCR, sequencing, and minigene construct. We detected 5 mutations: c.85C>T (Q29*), c.103C>T (Q35*), c.840-2A>G (R280Sfs*21), c.1027_1028delGA (D343*), and c.1174G>A (E392K). Mutations c.840-2A>G and c.1027_1028delGA were novel. The c.840-2A>G mutation at the splice acceptor site of intron 10 caused retention of intron 10 in the minigene construct but skipping of exon 11 in the peripheral blood cells. The latter was the most probable mechanism which caused a frameshift, changing Arg to Ser at residue 280 and invoking a premature termination of translation at codon 300 (R280Sfs*21). Five GNAS mutations in ethnic Chinese with PHP1A and PPHP were reported. Two of them were novel. Mutation c.840-2A>G destroyed a spice acceptor site and caused exon skipping. Regular monitoring and adjustment in therapy are mandatory to achieve optimal therapeutic effects and avoid nephrolithiasis in patients with PHP1A.
Collapse
|
32
|
Turan S, Fernandez-Rebollo E, Aydin C, Zoto T, Reyes M, Bounoutas G, Chen M, Weinstein LS, Erben RG, Marshansky V, Bastepe M. Postnatal establishment of allelic Gαs silencing as a plausible explanation for delayed onset of parathyroid hormone resistance owing to heterozygous Gαs disruption. J Bone Miner Res 2014; 29:749-60. [PMID: 23956044 PMCID: PMC3926912 DOI: 10.1002/jbmr.2070] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 07/26/2013] [Accepted: 08/02/2013] [Indexed: 12/16/2022]
Abstract
Pseudohypoparathyroidism type-Ia (PHP-Ia), characterized by renal proximal tubular resistance to parathyroid hormone (PTH), results from maternal mutations of GNAS that lead to loss of α-subunit of the stimulatory G protein (Gαs) activity. Gαs expression is paternally silenced in the renal proximal tubule, and this genomic event is critical for the development of PTH resistance, as patients display impaired hormone action only if the mutation is inherited maternally. The primary clinical finding of PHP-Ia is hypocalcemia, which can lead to various neuromuscular defects including seizures. PHP-Ia patients frequently do not present with hypocalcemia until after infancy, but it has remained uncertain whether PTH resistance occurs in a delayed fashion. Analyzing reported cases of PHP-Ia with documented GNAS mutations and mice heterozygous for disruption of Gnas, we herein determined that the manifestation of PTH resistance caused by the maternal loss of Gαs, ie, hypocalcemia and elevated serum PTH, occurs after early postnatal life. To investigate whether this delay could reflect gradual development of paternal Gαs silencing, we then analyzed renal proximal tubules isolated by laser capture microdissection from mice with either maternal or paternal disruption of Gnas. Our results revealed that, whereas expression of Gαs mRNA in this tissue is predominantly from the maternal Gnas allele at weaning (3 weeks postnatal) and in adulthood, the contributions of the maternal and paternal Gnas alleles to Gαs mRNA expression are equal at postnatal day 3. In contrast, we found that paternal Gαs expression is already markedly repressed in brown adipose tissue at birth. Thus, the mechanisms silencing the paternal Gαs allele in renal proximal tubules are not operational during early postnatal development, and this finding correlates well with the latency of PTH resistance in patients with PHP-Ia.
Collapse
Affiliation(s)
- Serap Turan
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Pediatric Endocrinology, Marmara University School of Medicine Hospital, Istanbul, Turkey
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Moreira IS. Structural features of the G-protein/GPCR interactions. Biochim Biophys Acta Gen Subj 2013; 1840:16-33. [PMID: 24016604 DOI: 10.1016/j.bbagen.2013.08.027] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 01/07/2023]
Abstract
BACKGROUND The details of the functional interaction between G proteins and the G protein coupled receptors (GPCRs) have long been subjected to extensive investigations with structural and functional assays and a large number of computational studies. SCOPE OF REVIEW The nature and sites of interaction in the G-protein/GPCR complexes, and the specificities of these interactions selecting coupling partners among the large number of families of GPCRs and G protein forms, are still poorly defined. MAJOR CONCLUSIONS Many of the contact sites between the two proteins in specific complexes have been identified, but the three dimensional molecular architecture of a receptor-Gα interface is only known for one pair. Consequently, many fundamental questions regarding this macromolecular assembly and its mechanism remain unanswered. GENERAL SIGNIFICANCE In the context of current structural data we review the structural details of the interfaces and recognition sites in complexes of sub-family A GPCRs with cognate G-proteins, with special emphasis on the consequences of activation on GPCR structure, the prevalence of preassembled GPCR/G-protein complexes, the key structural determinants for selective coupling and the possible involvement of GPCR oligomerization in this process.
Collapse
Affiliation(s)
- Irina S Moreira
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
| |
Collapse
|
34
|
Erickson CE, Gul R, Blessing CP, Nguyen J, Liu T, Pulakat L, Bastepe M, Jackson EK, Andresen BT. The β-blocker Nebivolol Is a GRK/β-arrestin biased agonist. PLoS One 2013; 8:e71980. [PMID: 23977191 PMCID: PMC3748024 DOI: 10.1371/journal.pone.0071980] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 07/07/2013] [Indexed: 01/14/2023] Open
Abstract
Nebivolol, a third generation β-adrenoceptor (β-AR) antagonist (β-blocker), causes vasodilation by inducing nitric oxide (NO) production. The mechanism via which nebivolol induces NO production remains unknown, resulting in the genesis of much of the controversy regarding the pharmacological action of nebivolol. Carvedilol is another β-blocker that induces NO production. A prominent pharmacological mechanism of carvedilol is biased agonism that is independent of Gαs and involves G protein-coupled receptor kinase (GRK)/β-arrestin signaling with downstream activation of the epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK). Due to the pharmacological similarities between nebivolol and carvedilol, we hypothesized that nebivolol is also a GRK/β-arrestin biased agonist. We tested this hypothesis utilizing mouse embryonic fibroblasts (MEFs) that solely express β2-ARs, and HL-1 cardiac myocytes that express β1- and β2-ARs and no detectable β3-ARs. We confirmed previous reports that nebivolol does not significantly alter cAMP levels and thus is not a classical agonist. Moreover, in both cell types, nebivolol induced rapid internalization of β-ARs indicating that nebivolol is also not a classical β-blocker. Furthermore, nebivolol treatment resulted in a time-dependent phosphorylation of ERK that was indistinguishable from carvedilol and similar in duration, but not amplitude, to isoproterenol. Nebivolol-mediated phosphorylation of ERK was sensitive to propranolol (non-selective β-AR-blocker), AG1478 (EGFR inhibitor), indicating that the signaling emanates from β-ARs and involves the EGFR. Furthermore, in MEFs, nebivolol-mediated phosphorylation of ERK was sensitive to pharmacological inhibition of GRK2 as well as siRNA knockdown of β-arrestin 1/2. Additionally, nebivolol induced redistribution of β-arrestin 2 from a diffuse staining pattern into more intense punctate spots. We conclude that nebivolol is a β2-AR, and likely β1-AR, GRK/β-arrestin biased agonist, which suggests that some of the unique clinically beneficial effects of nebivolol may be due to biased agonism at β1- and/or β2-ARs.
Collapse
Affiliation(s)
- Catherine E. Erickson
- Department of Internal Medicine, University of Missouri, Columbia, Missouri, United States of America
- Harry S Truman Memorial Veterans’ Hospital, Columbia, Missouri, United States of America
| | - Rukhsana Gul
- Department of Internal Medicine, University of Missouri, Columbia, Missouri, United States of America
- Harry S Truman Memorial Veterans’ Hospital, Columbia, Missouri, United States of America
- Obesity Research Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Christopher P. Blessing
- Department of Internal Medicine, University of Missouri, Columbia, Missouri, United States of America
| | - Jenny Nguyen
- Department of Pharmaceutical Sciences, Western University of Health Sciences, Pomona, California, United States of America
| | - Tammy Liu
- Department of Pharmaceutical Sciences, Western University of Health Sciences, Pomona, California, United States of America
| | - Lakshmi Pulakat
- Department of Internal Medicine, University of Missouri, Columbia, Missouri, United States of America
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States of America
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, United States of America
- Harry S Truman Memorial Veterans’ Hospital, Columbia, Missouri, United States of America
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Edwin K. Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh Pennsylvania, United States of America
| | - Bradley T. Andresen
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, United States of America
- Department of Pharmaceutical Sciences, Western University of Health Sciences, Pomona, California, United States of America
- * E-mail:
| |
Collapse
|
35
|
Ball ST, Kelly ML, Robson JE, Turner MD, Harrison J, Jones L, Napper D, Beechey CV, Hough T, Plagge A, Cattanach BM, Cox RD, Peters J. Gene Dosage Effects at the Imprinted Gnas Cluster. PLoS One 2013; 8:e65639. [PMID: 23822972 PMCID: PMC3688811 DOI: 10.1371/journal.pone.0065639] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 04/25/2013] [Indexed: 01/27/2023] Open
Abstract
Genomic imprinting results in parent-of-origin-dependent monoallelic gene expression. Early work showed that distal mouse chromosome 2 is imprinted, as maternal and paternal duplications of the region (with corresponding paternal and maternal deficiencies) give rise to different anomalous phenotypes with early postnatal lethalities. Newborns with maternal duplication (MatDp(dist2)) are long, thin and hypoactive whereas those with paternal duplication (PatDp(dist2)) are chunky, oedematous, and hyperactive. Here we focus on PatDp(dist2). Loss of expression of the maternally expressed Gnas transcript at the Gnas cluster has been thought to account for the PatDp(dist2) phenotype. But PatDp(dist2) also have two expressed doses of the paternally expressed Gnasxl transcript. Through the use of targeted mutations, we have generated PatDp(dist2) mice predicted to have 1 or 2 expressed doses of Gnasxl, and 0, 1 or 2 expressed doses of Gnas. We confirm that oedema is due to lack of expression of imprinted Gnas alone. We show that it is the combination of a double dose of Gnasxl, with no dose of imprinted Gnas, that gives rise to the characteristic hyperactive, chunky, oedematous, lethal PatDp(dist2) phenotype, which is also hypoglycaemic. However PatDp(dist2) mice in which the dosage of the Gnasxl and Gnas is balanced (either 2∶2 or 1∶1) are neither dysmorphic nor hyperactive, have normal glucose levels, and are fully viable. But PatDp(dist2) with biallelic expression of both Gnasxl and Gnas show a marked postnatal growth retardation. Our results show that most of the PatDp(dist2) phenotype is due to overexpression of Gnasxl combined with loss of expression of Gnas, and suggest that Gnasxl and Gnas may act antagonistically in a number of tissues and to cause a wide range of phenotypic effects. It can be concluded that monoallelic expression of both Gnasxl and Gnas is a requirement for normal postnatal growth and development.
Collapse
Affiliation(s)
- Simon T. Ball
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Michelle L. Kelly
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Joan E. Robson
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Martin D. Turner
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Jackie Harrison
- Medical Research Council Mary Lyon Centre, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Lynn Jones
- Medical Research Council Mary Lyon Centre, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Diane Napper
- Medical Research Council Mary Lyon Centre, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Colin V. Beechey
- Medical Research Council Mary Lyon Centre, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Tertius Hough
- Medical Research Council Mary Lyon Centre, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Antonius Plagge
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Bruce M. Cattanach
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Roger D. Cox
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
| | - Jo Peters
- Medical Research Council Mammalian Genetics Unit, Harwell Science and Innovation Campus, Harwell, Oxfordshire, United Kingdom
- * E-mail:
| |
Collapse
|
36
|
Turan S, Bastepe M. The GNAS complex locus and human diseases associated with loss-of-function mutations or epimutations within this imprinted gene. Horm Res Paediatr 2013; 80:229-41. [PMID: 24107509 PMCID: PMC3874326 DOI: 10.1159/000355384] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 08/29/2013] [Indexed: 12/14/2022] Open
Abstract
GNAS is a complex imprinted locus leading to several different gene products that show exclusive monoallelic expression. GNAS also encodes the α-subunit of the stimulatory G protein (Gsα), a ubiquitously expressed signaling protein that is essential for the actions of many hormones and other endogenous molecules. Gsα is expressed biallelically in most tissues but its expression is silenced from the paternal allele in a small number of tissues. The tissue-specific paternal silencing of Gsα results in different parent-of-origin-specific phenotypes in patients who carry inactivating GNAS mutations. In this paper, we review the GNAS complex locus and discuss how disruption of Gsα expression and the expression of other GNAS products shape the phenotypes of human disorders caused by mutations in this gene.
Collapse
Affiliation(s)
- Serap Turan
- Pediatric Endocrinology, Marmara University School of Medicine Hospital, Istanbul, Turkey
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| |
Collapse
|
37
|
Liu JJ, Russell E, Zhang D, Kaplan FS, Pignolo RJ, Shore EM. Paternally inherited gsα mutation impairs adipogenesis and potentiates a lean phenotype in vivo. Stem Cells 2012; 30:1477-85. [PMID: 22511293 DOI: 10.1002/stem.1109] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Paternally inherited inactivating mutations of the GNAS gene have been associated with a rare and disabling genetic disorder, progressive osseous heteroplasia, in which heterotopic ossification occurs within extraskeletal soft tissues, such as skin, subcutaneous fat, and skeletal muscle. This ectopic bone formation is hypothesized to be caused by dysregulated mesenchymal progenitor cell differentiation that affects a bipotential osteogenic-adipogenic lineage cell fate switch. Interestingly, patients with paternally inherited inactivating mutations of GNAS are uniformly lean. Using a mouse model of Gsα-specific exon 1 disruption, we examined whether heterozygous inactivation of Gnas affects adipogenic differentiation of mesenchymal precursor cells from subcutaneous adipose tissues (fat pad). We found that paternally inherited Gsα inactivation (Gsα(+/p-) ) impairs adipogenic differentiation of adipose-derived stromal cells (ASCs). The Gsα(+/p-) mutation in ASCs also decreased expression of the adipogenic factors CCAAT-enhancer-binding protein (C/EBP)β, C/EBPα, peroxisome proliferator-activated receptor gamma, and adipocyte protein 2. Impaired adipocyte differentiation was rescued by an adenylyl cyclase activator, forskolin, and provided evidence that Gsα-cAMP signals are necessary in early stages of this process. Supporting a role for Gnas in adipogenesis in vivo, fat tissue weight and expression of adipogenic genes from multiple types of adipose tissues from Gsα(+/p-) mice were significantly decreased. Interestingly, the inhibition of adipogenesis by paternally inherited Gsα mutation also enhances expression of the osteogenic factors, msh homeobox 2, runt-related transcription factor 2, and osteocalcin. These data support the hypothesis that Gsα plays a critical role in regulating the balance between fat and bone determination in soft tissues, a finding that has important implications for a wide variety of disorders of osteogenesis and adipogenesis.
Collapse
Affiliation(s)
- Jan-jan Liu
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | |
Collapse
|
38
|
Zhang S, Kaplan FS, Shore EM. Different roles of GNAS and cAMP signaling during early and late stages of osteogenic differentiation. Horm Metab Res 2012; 44:724-31. [PMID: 22903279 PMCID: PMC3557937 DOI: 10.1055/s-0032-1321845] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Progressive osseous heteroplasia (POH) and fibrous dysplasia (FD) are genetic diseases of bone formation at opposite ends of the osteogenic spectrum: imperfect osteogenesis of the skeleton occurs in FD, while heterotopic ossification in skin, subcutaneous fat, and skeletal muscle forms in POH. POH is caused by heterozygous inactivating germline mutations in GNAS, which encodes G-protein subunits regulating the cAMP pathway, while FD is caused by GNAS somatic activating mutations. We used pluripotent mouse ES cells to examine the effects of Gnas dysregulation on osteoblast differentiation. At the earliest stages of osteogenesis, Gnas transcripts Gsα, XLαs and 1A are expressed at low levels and cAMP levels are also low. Inhibition of cAMP signaling (as in POH) by 2',5'-dideoxyadenosine enhanced osteoblast differentiation while conversely, increased cAMP signaling (as in FD), induced by forskolin, inhibited osteoblast differentiation. Notably, increased cAMP was inhibitory for osteogenesis only at early stages after osteogenic induction. Expression of osteogenic and adipogenic markers showed that increased cAMP enhanced adipogenesis and impaired osteoblast differentiation even in the presence of osteogenic factors, supporting cAMP as a critical regulator of osteoblast and adipocyte lineage commitment. Furthermore, increased cAMP signaling decreased BMP pathway signaling, indicating that G protein-cAMP pathway activation (as in FD) inhibits osteoblast differentiation, at least in part by blocking the BMP-Smad pathway, and suggesting that GNAS inactivation as occurs in POH enhances osteoblast differentiation, at least in part by stimulating BMP signaling. These data support that differences in cAMP levels during early stages of cell differentiation regulate cell fate decisions. Supporting information available online at http:/www.thieme-connect.de/ejournals/toc/hmr.
Collapse
Affiliation(s)
- S. Zhang
- Department of Orthopaedic Surgery and the Center for Research in FOP and Related Disorders, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - F. S. Kaplan
- Department of Orthopaedic Surgery and the Center for Research in FOP and Related Disorders, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
- Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - E. M. Shore
- Department of Orthopaedic Surgery and the Center for Research in FOP and Related Disorders, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
39
|
Fernández-Rebollo E, Maeda A, Reyes M, Turan S, Fröhlich LF, Plagge A, Kelsey G, Jüppner H, Bastepe M. Loss of XLαs (extra-large αs) imprinting results in early postnatal hypoglycemia and lethality in a mouse model of pseudohypoparathyroidism Ib. Proc Natl Acad Sci U S A 2012; 109:6638-43. [PMID: 22496590 PMCID: PMC3340037 DOI: 10.1073/pnas.1117608109] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maternal deletion of the NESP55 differentially methylated region (DMR) (delNESP55/ASdel3-4(m), delNAS(m)) from the GNAS locus in humans causes autosomal dominant pseudohypoparathyroidism type Ib (AD-PHP-Ib(delNASm)), a disorder of proximal tubular parathyroid hormone (PTH) resistance associated with loss of maternal GNAS methylation imprints. Mice carrying a similar, maternally inherited deletion of the Nesp55 DMR (ΔNesp55(m)) replicate these Gnas epigenetic abnormalities and show evidence for PTH resistance, yet these mice demonstrate 100% mortality during the early postnatal period. We investigated whether the loss of extralarge αs (XLαs) imprinting and the resultant biallelic expression of XLαs are responsible for the early postnatal lethality in ΔNesp55(m) mice. First, we found that ΔNesp55(m) mice are hypoglycemic and have reduced stomach-to-body weight ratio. We then generated mice having the same epigenetic abnormalities as the ΔNesp55(m) mice but with normalized XLαs expression due to the paternal disruption of the exon giving rise to this Gnas product. These mice (ΔNesp55(m)/Gnasxl(m+/p-)) showed nearly 100% survival up to postnatal day 10, and a substantial number of them lived to adulthood. The hypoglycemia and reduced stomach-to-body weight ratio observed in 2-d-old ΔNesp55(m) mice were rescued in the ΔNesp55(m)/Gnasxl(m+/p-) mice. Surviving double-mutant animals had significantly reduced Gαs mRNA levels and showed hypocalcemia, hyperphosphatemia, and elevated PTH levels, thus providing a viable model of human AD-PHP-Ib. Our findings show that the hypoglycemia and early postnatal lethality caused by the maternal deletion of the Nesp55 DMR result from biallelic XLαs expression. The double-mutant mice will help elucidate the pathophysiological mechanisms underlying AD-PHP-Ib.
Collapse
Affiliation(s)
| | | | | | - Serap Turan
- Endocrine Unit, Department of Medicine, and
- Pediatric Endocrinology, Marmara University School of Medicine, Istanbul 34899, Turkey
| | - Leopold F. Fröhlich
- Endocrine Unit, Department of Medicine, and
- Institute of Pathology, Medical University of Graz, 8036 Graz, Austria
| | - Antonius Plagge
- Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Gavin Kelsey
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, United Kingdom; and
- Centre for Trophoblast Research, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Harald Jüppner
- Endocrine Unit, Department of Medicine, and
- Pediatric Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114
| | | |
Collapse
|
40
|
Dopamine D(2) Receptor-Mediated Heterologous Sensitization of AC5 Requires Signalosome Assembly. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:210324. [PMID: 22523680 PMCID: PMC3317181 DOI: 10.1155/2012/210324] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 12/28/2011] [Indexed: 12/23/2022]
Abstract
Chronic dopamine receptor activation is implicated in several central nervous system disorders. Although acute activation of Gαi-coupled D2 dopamine receptors inhibits adenylyl cyclase, persistent activation enhances adenylyl cyclase activity, a phenomenon called heterologous sensitization. Previous work revealed a requirement for Gαs in D2-induced heterologous sensitization of AC5. To elucidate the mechanism of Gαs dependency, we expressed Gαs mutants in Gαs-deficient GnasE2−/E2−
cells. Neither Gαs-palmitoylation nor Gαs-Gβγ interactions were required for sensitization of AC5. Moreover, we found that coexpressing βARKct-CD8 or Sar1(H79G) blocked heterologous sensitization. These studies are consistent with a role for Gαs-AC5 interactions in sensitization however, Gβγ appears to have an indirect role in heterologous sensitization of AC5, possibly by promoting proper signalosome assembly.
Collapse
|
41
|
Krechowec SO, Burton KL, Newlaczyl AU, Nunn N, Vlatković N, Plagge A. Postnatal changes in the expression pattern of the imprinted signalling protein XLαs underlie the changing phenotype of deficient mice. PLoS One 2012; 7:e29753. [PMID: 22253771 PMCID: PMC3256176 DOI: 10.1371/journal.pone.0029753] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 12/05/2011] [Indexed: 11/18/2022] Open
Abstract
The alternatively spliced trimeric G-protein subunit XLαs, which is involved in cAMP signalling, is encoded by the Gnasxl transcript of the imprinted Gnas locus. XLαs deficient mice show neonatal feeding problems, leanness, inertia and a high mortality rate. Mutants that survive to weaning age develop into healthy and fertile adults, which remain lean despite elevated food intake. The adult metabolic phenotype can be attributed to increased energy expenditure, which appears to be caused by elevated sympathetic nervous system activity. To better understand the changing phenotype of Gnasxl deficient mice, we compared XLαs expression in neonatal versus adult tissues, analysed its co-localisation with neural markers and characterised changes in the nutrient-sensing mTOR1-S6K pathway in the hypothalamus. Using a newly generated conditional Gnasxl lacZ gene trap line and immunohistochemistry we identified various types of muscle, including smooth muscle cells of blood vessels, as the major peripheral sites of expression in neonates. Expression in all muscle tissues was silenced in adults. While Gnasxl expression in the central nervous system was also developmentally silenced in some midbrain nuclei, it was upregulated in the preoptic area, the medial amygdala, several hypothalamic nuclei (e.g. arcuate, dorsomedial, lateral and paraventricular nuclei) and the nucleus of the solitary tract. Furthermore, expression was detected in the ventral medulla as well as in motoneurons and a subset of sympathetic preganglionic neurons of the spinal cord. In the arcuate nucleus of Gnasxl-deficient mice we found reduced activity of the nutrient sensing mTOR1-S6K signalling pathway, which concurs with their metabolic status. The expression in these brain regions and the hypermetabolic phenotype of adult Gnasxl-deficient mice imply an inhibitory function of XLαs in energy expenditure and sympathetic outflow. By contrast, the neonatal phenotype of mutant mice appears to be due to a transient role of XLαs in muscle tissues.
Collapse
Affiliation(s)
- Stefan O. Krechowec
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Katie L. Burton
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Anna U. Newlaczyl
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nicolas Nunn
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nikolina Vlatković
- Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Antonius Plagge
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| |
Collapse
|
42
|
New mutations at the imprinted Gnas cluster show gene dosage effects of Gsα in postnatal growth and implicate XLαs in bone and fat metabolism but not in suckling. Mol Cell Biol 2012; 32:1017-29. [PMID: 22215617 DOI: 10.1128/mcb.06174-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The imprinted Gnas cluster is involved in obesity, energy metabolism, feeding behavior, and viability. Relative contribution of paternally expressed proteins XLαs, XLN1, and ALEX or a double dose of maternally expressed Gsα to phenotype has not been established. In this study, we have generated two new mutants (Ex1A-T-CON and Ex1A-T) at the Gnas cluster. Paternal inheritance of Ex1A-T-CON leads to loss of imprinting of Gsα, resulting in preweaning growth retardation followed by catch-up growth. Paternal inheritance of Ex1A-T leads to loss of imprinting of Gsα and loss of expression of XLαs and XLN1. These mice have severe preweaning growth retardation and incomplete catch-up growth. They are fully viable probably because suckling is unimpaired, unlike mutants in which the expression of all the known paternally expressed Gnasxl proteins (XLαs, XLN1 and ALEX) is compromised. We suggest that loss of ALEX is most likely responsible for the suckling defects previously observed. In adults, paternal inheritance of Ex1A-T results in an increased metabolic rate and reductions in fat mass, leptin, and bone mineral density attributable to loss of XLαs. This is, to our knowledge, the first report describing a role for XLαs in bone metabolism. We propose that XLαs is involved in the regulation of bone and adipocyte metabolism.
Collapse
|
43
|
Pignolo RJ, Xu M, Russell E, Richardson A, Kaplan J, Billings PC, Kaplan FS, Shore EM. Heterozygous inactivation of Gnas in adipose-derived mesenchymal progenitor cells enhances osteoblast differentiation and promotes heterotopic ossification. J Bone Miner Res 2011; 26:2647-55. [PMID: 21812029 PMCID: PMC3584579 DOI: 10.1002/jbmr.481] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Human genetic disorders sharing the common feature of subcutaneous heterotopic ossification (HO) are caused by heterozygous inactivating mutations in GNAS, a gene encoding multiple transcripts including two stimulatory G proteins, the α subunit of the stimulatory G protein (G(s)α) of adenylyl cyclase, and the extralong form of G(s)α, XLαs. In one such disorder, progressive osseous heteroplasia (POH), bone formation initiates within subcutaneous fat before progressing to deeper tissues, suggesting that osteogenesis may involve abnormal differentiation of mesenchymal precursors that are present in adipose tissues. We determined by immunohistochemical analysis that GNAS protein expression is limited to G(s)α in bone-lining cells and to G(s)α and XLαs in osteocytes. By contrast, the GNAS proteins G(s)α, XLαs, and NESP55 are detected in adipocytes and in adipose stroma. Although Gnas transcripts, as assessed by quantitative RT-PCR, show no significant changes on osteoblast differentiation of bone-derived precursor cells, the abundance of these transcripts is enhanced by osteoblast differentiation of adipose-derived mesenchymal progenitors. Using a mouse knockout model, we determined that heterozygous inactivation of Gnas (by disruption of the G(s)α-specific exon 1) abrogates upregulation of multiple Gnas transcripts that normally occurs with osteoblast differentiation in wild-type adipose stromal cells. These transcriptional changes in Gnas(+/-) mice are accompanied by accelerated osteoblast differentiation of adipose stromal cells in vitro. In vivo, altered osteoblast differentiation in Gnas(+/-) mice manifests as subcutaneous HO by an intramembranous process. Taken together, these data suggest that Gnas is a key regulator of fate decisions in adipose-derived mesenchymal progenitor cells, specifically those which are involved in bone formation.
Collapse
Affiliation(s)
- Robert J Pignolo
- Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Divergent agonist selectivity in activating β1- and β2-adrenoceptors for G-protein and arrestin coupling. Biochem J 2011; 438:191-202. [PMID: 21561432 DOI: 10.1042/bj20110374] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The functional selectivity of adrenergic ligands for activation of β1- and β2-AR (adrenoceptor) subtypes has been extensively studied in cAMP signalling. Much less is known about ligand selectivity for arrestin-mediated signalling pathways. In the present study we used resonance energy transfer methods to compare the ability of β1- and β2-ARs to form a complex with the G-protein β-subunit or β-arrestin-2 in response to a variety of agonists with various degrees of efficacy. The profiles of β1-/β2-AR selectivity of the ligands for the two receptor-transducer interactions were sharply different. For G-protein coupling, the majority of ligands were more effective in activating the β2-AR, whereas for arrestin coupling the relationship was reversed. These data indicate that the β1-AR interacts more efficiently than β2-AR with arrestin, but less efficiently than β2-AR with G-protein. A group of ligands exhibited β1-AR-selective efficacy in driving the coupling to arrestin. Dobutamine, a member of this group, had 70% of the adrenaline (epinephrine) effect on arrestin via β1-AR, but acted as a competitive antagonist of adrenaline via β2-AR. Thus the structure of such ligands appears to induce an arrestin-interacting form of the receptor only when bound to the β1-AR subtype.
Collapse
|
45
|
Puzhko S, Goodyer CG, Kerachian MA, Canaff L, Misra M, Jüppner H, Bastepe M, Hendy GN. Parathyroid hormone signaling via Gαs is selectively inhibited by an NH(2)-terminally truncated Gαs: implications for pseudohypoparathyroidism. J Bone Miner Res 2011; 26:2473-85. [PMID: 21713996 PMCID: PMC3916968 DOI: 10.1002/jbmr.461] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pseudohypoparathyroid patients have resistance predominantly to parathyroid hormone (PTH), and here we have examined the ability of an alternative Gαs-related protein to inhibit Gαs activity in a hormone-selective manner. We tested whether the GNAS exon A/B-derived NH(2)-terminally truncated (Tr) αs protein alters stimulation of adenylate cyclase by the PTH receptor (PTHR1), the thyroid-stimulating hormone (TSH) receptor (TSHR), the β(2)-adrenergic receptor (β(2)AR), or the AVP receptor (V2R). HEK293 cells cotransfected with receptor and full-length (FL) Gαs ± Tr αs protein expression vectors were stimulated with agonists (PTH [10(-7) to 10(-9) M], TSH [1 to 100 mU], isoproterenol [10(-6) to 10(-8) M], or AVP [10(-6) to 10(-8) M]). Following PTH stimulation, HEK293 cells cotransfected with PTHR1 + FL Gαs + Tr αs had a significantly lower cAMP response than those transfected with only PTHR1 + FL Gαs. Tr αs also exerted an inhibitory effect on the cAMP levels stimulated by TSH via the TSHR but had little or no effect on isoproterenol or AVP acting via β(2)AR or V2R, respectively. These differences mimic the spectrum of hormone resistance in pseudohypoparathyroidism type 1a (PHP-1a) and type 1b (PHP-1b) patients. In opossum kidney (OK) cells, endogenously expressing the PTHR1 and β(2)AR, the exogenous expression of Tr αs at a level similar to endogenous FL Gαs resulted in blunting of the cAMP response to PTH, whereas that to isoproterenol was unaltered. A pseudopseudohypoparathyroid patient with Albright hereditary osteodystrophy harbored a de novo paternally inherited M1I Gαs mutation. Similar maternally inherited mutations at the initiation codon have been identified previously in PHP-1a patients. The M1I αs mutant (lacking the first 59 amino acids of Gαs) blunted the increase in cAMP levels stimulated via the PTHR1 in both HEK293 and OK cells similar to the Tr αs protein. Thus NH(2)-terminally truncated forms of Gαs may contribute to the pathogenesis of pseudohypoparathyroidism by inhibiting the activity of Gαs itself in a GPCR selective manner.
Collapse
Affiliation(s)
- Svetlana Puzhko
- Endocrine Research Laboratory, McGill University, Montreal, Quebec, Canada
| | - Cynthia Gates Goodyer
- Endocrine Research Laboratory, McGill University, Montreal, Quebec, Canada
- Department of Pediatrics, McGill University, Montreal, Quebec, Canada
- Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Mohammad Amin Kerachian
- Calcium Research Laboratory, Royal Victoria Hospital, Montreal, Quebec, Canada
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Lucie Canaff
- Calcium Research Laboratory, Royal Victoria Hospital, Montreal, Quebec, Canada
| | - Madhusmita Misra
- Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Pediatric Endocrine Unit, MassGeneral for Children and Harvard Medical School, Boston, MA, USA
| | - Harald Jüppner
- Pediatric Nephrology Unit, MassGeneral for Children and Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Geoffrey N Hendy
- Department of Medicine, McGill University, Montreal, Quebec, Canada
- Calcium Research Laboratory, Royal Victoria Hospital, Montreal, Quebec, Canada
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- Department of Physiology, McGill University, Montreal, Quebec, Canada
- Hormones and Cancer Research Unit, Royal Victoria Hospital, Montreal, Quebec, Canada
| |
Collapse
|
46
|
Abstract
Genomic imprinting is an important and enigmatic form of gene regulation in mammals in which one copy of a gene is silenced in a manner determined by its parental history. Imprinted genes range from those with constitutive monoallelic silencing to those, typically more remote from imprinting control regions, that display developmentally regulated, tissue-specific or partial monoallelic expression. This diversity may make these genes, and the processes they control, more or less sensitive to factors that modify or disrupt epigenetic marks. Imprinted genes have important functions in development and physiology, including major endocrine/neuroendocrine axes. Owing to is central role in coordinating growth, metabolism and reproduction, as well as evidence from genetic and knockout studies, the hypothalamus may be a focus for imprinted gene action. Are there unifying principles that explain why a gene should be imprinted? Conflict between parental genomes over limiting maternal resources, but also co-adaptation between mothers and offspring, have been invoked to explain the evolution of imprinting. Recent reports suggest there may be many more genes imprinted in the hypothalamus than hitherto expected, and it will be important for these new candidates to be validated and to determine whether they conform to current notions of how imprinting is regulated. In fully evaluating the role of imprinted genes in the hypothalamus, much work needs to be done to identify the specific neuronal populations in which particular genes are expressed, establish whether there are pathways in common and whether imprinted genes are involved in long-term programming of hypothalamic functions.
Collapse
Affiliation(s)
- Elena Ivanova
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | | |
Collapse
|
47
|
Liu Z, Turan S, Wehbi VL, Vilardaga JP, Bastepe M. Extra-long Gαs variant XLαs protein escapes activation-induced subcellular redistribution and is able to provide sustained signaling. J Biol Chem 2011; 286:38558-38569. [PMID: 21890629 DOI: 10.1074/jbc.m111.240150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Murine models indicate that Gαs and its extra-long variant XLαs, both of which are derived from GNAS, markedly differ regarding their cellular actions, but these differences are unknown. Here we investigated activation-induced trafficking of Gαs and XLαs, using immunofluorescence microscopy, cell fractionation, and total internal reflection fluorescence microscopy. In transfected cells, XLαs remained localized to the plasma membrane, whereas Gαs redistributed to the cytosol after activation by GTPase-inhibiting mutations, cholera toxin treatment, or G protein-coupled receptor agonists (isoproterenol or parathyroid hormone (PTH)(1-34)). Cholera toxin treatment or agonist (isoproterenol or pituitary adenylate cyclase activating peptide-27) stimulation of PC12 cells expressing Gαs and XLαs endogenously led to an increased abundance of Gαs, but not XLαs, in the soluble fraction. Mutational analyses revealed two conserved cysteines and the highly charged domain as being critically involved in the plasma membrane anchoring of XLαs. The cAMP response induced by M-PTH(1-14), a parathyroid hormone analog, terminated quickly in HEK293 cells stably expressing the type 1 PTH/PTH-related peptide receptor, whereas the response remained maximal for at least 6 min in cells that co-expressed the PTH receptor and XLαs. Although isoproterenol-induced cAMP response was not prolonged by XLαs expression, a GTPase-deficient XLαs mutant found in certain tumors and patients with fibrous dysplasia of bone and McCune-Albright syndrome generated more basal cAMP accumulation in HEK293 cells and caused more severe impairment of osteoblastic differentiation of MC3T3-E1 cells than the cognate Gαs mutant (gsp oncogene). Thus, activated XLαs and Gαs traffic differently, and this may form the basis for the differences in their cellular actions.
Collapse
Affiliation(s)
- Zun Liu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Serap Turan
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Pediatric Endocrinology, Marmara University School of Medicine Hospital, 34662 Istanbul, Turkey
| | - Vanessa L Wehbi
- Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Jean-Pierre Vilardaga
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
| |
Collapse
|
48
|
Bastepe M. The GNAS Locus: Quintessential Complex Gene Encoding Gsalpha, XLalphas, and other Imprinted Transcripts. Curr Genomics 2011; 8:398-414. [PMID: 19412439 PMCID: PMC2671723 DOI: 10.2174/138920207783406488] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2007] [Revised: 09/22/2007] [Accepted: 09/28/2007] [Indexed: 12/14/2022] Open
Abstract
The currently estimated number of genes in the human genome is much smaller than previously predicted. As an explanation for this disparity, most individual genes have multiple transcriptional units that represent a variety of biologically important gene products. GNAS exemplifies a gene of such complexity. One of its products is the alpha-subunit of the stimulatory heterotrimeric G protein (Gsalpha), a ubiquitous signaling protein essential for numerous different cellular responses. Loss-of-function and gain-of-function mutations within Gsalpha-coding GNAS exons are found in various human disorders, including Albright's hereditary osteodystrophy, pseudohypoparathyroidism, fibrous dysplasia of bone, and some tumors of different origin. While Gsalpha expression in most tissues is biallelic, paternal Gsalpha expression is silenced in a small number of tissues, playing an important role in the development of phenotypes associated with GNAS mutations. Additional products derived exclusively from the paternal GNAS allele include XLalphas, a protein partially identical to Gsalpha, and two non-coding RNA molecules, the A/B transcript and the antisense transcript. The maternal GNAS allele leads to NESP55, a chromogranin-like neuroendocrine secretory protein. In vivo animal models have demonstrated the importance of each of the exclusively imprinted GNAS products in normal mammalian physiology. However, although one or more of these products are also disrupted by most naturally occurring GNAS mutations, their roles in disease pathogenesis remain unknown. To further our understanding of the significance of this gene in physiology and pathophysiology, it will be important to elucidate the cellular roles and the mechanisms regulating the expression of each GNAS product.
Collapse
Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| |
Collapse
|
49
|
Thiele S, de Sanctis L, Werner R, Grötzinger J, Aydin C, Jüppner H, Bastepe M, Hiort O. Functional characterization of GNAS mutations found in patients with pseudohypoparathyroidism type Ic defines a new subgroup of pseudohypoparathyroidism affecting selectively Gsα-receptor interaction. Hum Mutat 2011; 32:653-60. [PMID: 21488135 DOI: 10.1002/humu.21489] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 02/09/2011] [Indexed: 01/09/2023]
Abstract
Pseudohypoparathyroidism type Ia (PHPIa) is caused by GNAS mutations leading to deficiency of the α-subunit of stimulatory G proteins (Gsα) that mediate signal transduction of G protein-coupled receptors via cAMP. PHP type Ic (PHPIc) and PHPIa share clinical features of Albright hereditary osteodystrophy (AHO); however, in vitro activity of solubilized Gsα protein is normal in PHPIc but reduced in PHPIa. We screened 32 patients classified as PHPIc for GNAS mutations and identified three mutations (p.E392K, p.E392X, p.L388R) in four unrelated families. These and one novel mutation associated with PHPIa (p.L388P) were introduced into a pcDNA3.1(-) expression vector encoding Gsα wild-type and expressed in a Gsα-null cell line (Gnas(E2-/E2-) ). To investigate receptor-mediated cAMP accumulation, we stimulated the endogenous expressed β(2) -adrenergic receptor, or the coexpressed PTH or TSH receptors, and measured the synthesized cAMP by RIA. The results were compared to receptor-independent cholera toxin-induced cAMP accumulation. Each of the mutants associated with PHPIc significantly reduced or completely disrupted receptor-mediated activation, but displayed normal receptor-independent activation. In contrast, PHPIa associated p.L388P disrupted both receptor-mediated activation and receptor-independent activation. We present a new subgroup of PHP that is caused by Gsα deficiency and selectively affects receptor coupling functions of Gsα.
Collapse
Affiliation(s)
- Susanne Thiele
- Department of Pediatrics and Adolescent Medicine, University of Lübeck, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Liu Z, Segawa H, Aydin C, Reyes M, Erben RG, Weinstein LS, Chen M, Marshansky V, Fröhlich LF, Bastepe M. Transgenic overexpression of the extra-large Gsα variant XLαs enhances Gsα-mediated responses in the mouse renal proximal tubule in vivo. Endocrinology 2011; 152:1222-33. [PMID: 21303955 PMCID: PMC3060637 DOI: 10.1210/en.2010-1034] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
XLαs, a variant of the stimulatory G protein α-subunit (Gsα), can mediate receptor-activated cAMP generation and, thus, mimic the actions of Gsα in transfected cells. However, it remains unknown whether XLαs can act in a similar manner in vivo. We have now generated mice with ectopic transgenic expression of rat XLαs in the renal proximal tubule (rptXLαs mice), where Gsα mediates most actions of PTH. Western blots and quantitative RT-PCR showed that, while Gsα and type-1 PTH receptor levels were unaltered, protein kinase A activity and 25-hydroxyvitamin D 1-α-hydroxylase (Cyp27b1) mRNA levels were significantly higher in renal proximal tubules of rptXLαs mice than wild-type littermates. Immunohistochemical analysis of kidney sections showed that the sodium-phosphate cotransporter type 2a was modestly reduced in brush border membranes of male rptXLαs mice compared to gender-matched controls. Serum calcium, phosphorus, and 1,25 dihydroxyvitamin D were within the normal range, but serum PTH was ∼30% lower in rptXLαs mice than in controls (152 ± 16 vs. 222 ± 41 pg/ml; P < 0.05). After crossing the rptXLαs mice to mice with ablation of maternal Gnas exon 1 (E1(m-/+)), male offspring carrying both the XLαs transgene and maternal Gnas exon 1 ablation (rptXLαs/E1(m-/+)) were significantly less hypocalcemic than gender-matched E1(m-/+) littermates. Both E1(m-/+) and rptXLαs/E1(m-/+) offspring had higher serum PTH than wild-type littermates, but the degree of secondary hyperparathyroidism tended to be lower in rptXLαs/E1(m-/+) mice. Hence, transgenic XLαs expression in the proximal tubule enhanced Gsα-mediated responses, indicating that XLαs can mimic Gsα in vivo.
Collapse
Affiliation(s)
- Zun Liu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, 50 Blossom Street, Thier 10, Boston, Massachusetts 02114, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|