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Renard E, Thevenard-Berger A, Meyre D. Medical semiology of patients with monogenic obesity: A systematic review. Obes Rev 2024:e13797. [PMID: 38956946 DOI: 10.1111/obr.13797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 03/20/2024] [Accepted: 06/19/2024] [Indexed: 07/04/2024]
Abstract
Patients with monogenic obesity display numerous medical features on top of hyperphagic obesity, but no study to date has provided an exhaustive description of their semiology. Two reviewers independently conducted a systematic review of MEDLINE, Embase, and Web of Science Core Collection databases from inception to January 2022 to identify studies that described symptoms of patients carrying pathogenic mutations in at least one of eight monogenic obesity genes (ADCY3, LEP, LEPR, MC3R, MC4R, MRAP2, PCSK1, and POMC). Of 5207 identified references, 269 were deemed eligible after title and abstract screening, full-text reading, and risk of bias and quality assessment. Data extraction included mutation spectrum and mode of inheritance, clinical presentation (e.g., anthropometry, energy intake and eating behaviors, digestive function, puberty and fertility, cognitive features, infectious diseases, morphological characteristics, chronic respiratory disease, and cardiovascular disease), biological characteristics (metabolic profile, endocrinology, hematology), radiological features, and treatments. The review provides an exhaustive description of mandatory, non-mandatory, and unique symptoms in heterozygous and homozygous carriers of mutation in eight monogenic obesity genes. This information is critical to help clinicians to orient genetic testing in subsets of patients with suspected monogenic obesity and provide actionable treatments (e.g., recombinant leptin and MC4R agonist).
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Affiliation(s)
- Emeline Renard
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
- Department of Pediatrics, University Hospital of Nancy, Nancy, France
| | | | - David Meyre
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
- Department of Molecular Medicine, Division of Biochemistry, Molecular Biology, and Nutrition, University Hospital of Nancy, Nancy, France
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada
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2
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Monteiro-Martins S, Sterenborg RBTM, Borisov O, Scherer N, Cheng Y, Medici M, Köttgen A, Teumer A. New insights into the hypothalamic-pituitary-thyroid axis: a transcriptome- and proteome-wide association study. Eur Thyroid J 2024; 13:e240067. [PMID: 38805593 PMCID: PMC11227097 DOI: 10.1530/etj-24-0067] [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: 03/12/2024] [Accepted: 05/28/2024] [Indexed: 05/30/2024] Open
Abstract
Introduction Thyroid hormones have systemic effects on the human body and play a key role in the development and function of virtually all tissues. They are regulated via the hypothalamic-pituitary-thyroid (HPT) axis and have a heritable component. Using genetic information, we applied tissue-specific transcriptome-wide association studies (TWAS) and plasma proteome-wide association studies (PWAS) to elucidate gene products related to thyrotropin (TSH) and free thyroxine (FT4) levels. Results TWAS identified 297 and 113 transcripts associated with TSH and FT4 levels, respectively (25 shared), including transcripts not identified by genome-wide association studies (GWAS) of these traits, demonstrating the increased power of this approach. Testing for genetic colocalization revealed a shared genetic basis of 158 transcripts with TSH and 45 transcripts with FT4, including independent, FT4-associated genetic signals within the CAPZB locus that were differentially associated with CAPZB expression in different tissues. PWAS identified 18 and ten proteins associated with TSH and FT4, respectively (HEXIM1 and QSOX2 with both). Among these, the cognate genes of five TSH- and 7 FT4-associated proteins mapped outside significant GWAS loci. Colocalization was observed for five plasma proteins each with TSH and FT4. There were ten TSH and one FT4-related gene(s) significant in both TWAS and PWAS. Of these, ANXA5 expression and plasma annexin A5 levels were inversely associated with TSH (PWAS: P = 1.18 × 10-13, TWAS: P = 7.61 × 10-12 (whole blood), P = 6.40 × 10-13 (hypothalamus), P = 1.57 × 10-15 (pituitary), P = 4.27 × 10-15 (thyroid)), supported by colocalizations. Conclusion Our analyses revealed new thyroid function-associated genes and prioritized candidates in known GWAS loci, contributing to a better understanding of transcriptional regulation and protein levels relevant to thyroid function.
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Affiliation(s)
- Sara Monteiro-Martins
- Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center – University of Freiburg, Freiburg, Germany
| | - Rosalie B T M Sterenborg
- Division of Endocrinology, Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Oleg Borisov
- Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center – University of Freiburg, Freiburg, Germany
| | - Nora Scherer
- Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center – University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Yurong Cheng
- Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center – University of Freiburg, Freiburg, Germany
| | - Marco Medici
- Division of Endocrinology, Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Anna Köttgen
- Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center – University of Freiburg, Freiburg, Germany
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Alexander Teumer
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, Greifswald, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Greifswald, Greifswald, Germany
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Guijo B, Argente J, Martos-Moreno GÁ. The N221D variant in PCSK1 is highly prevalent in childhood obesity and can influence the metabolic profile. J Pediatr Endocrinol Metab 2023; 36:1140-1145. [PMID: 37877373 DOI: 10.1515/jpem-2023-0395] [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: 08/31/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023]
Abstract
OBJECTIVES To study the prevalence and influence on metabolic profile of the prohormone-convertase-1 (PCSK1) N221D variant in childhood obesity, proven its role in the leptin-melanocortin signaling pathway as in proinsulin and other prohormone cleavage. METHODS Transversal study of 1066 children with obesity (mean age and BMI Z-score 10.38 ± 3.44 years and +4.38 ± 1.77, respectively), 51.4 % males, 54.4 % prepubertal, 71.5 % Caucasians and 20.8 % Latinos. Anthropometric and metabolic features were compared between patients carrying the N221D variant in PCSK1 and patients with no variants found after next generation sequencing analysis of 17 genes (CREBBP, CPE, HTR2C, KSR2, LEP, LEPR, MAGEL2, MC3R, MC4R, MRAP2, NCOA1, PCSK1, POMC, SH2B1, SIM1, TBX3 and TUB) involved in the leptin-melanocortin pathway. RESULTS No variants were found in 531 patients (49.8 %), while 68 patients carried the PCSK1 N221D variant (42 isolately, and 26 with at least one additional gene variant). Its prevalence was higher in Caucasians vs. Latinos (χ2 7.81; p<0.01). Patients carrying exclusively the PCSK1 N221D variant (n=42) showed lower insulinemia (p<0.05), HOMA index (p<0.05) and area under the curve for insulin in the oral glucose tolerance test (p<0.001) and higher WBISI (p<0.05) than patients with no variants, despite similar obesity severity, age, sex and ethnic distribution. CONCLUSIONS The N221D variant in PCSK1 is highly prevalent in childhood obesity, influenced by ethnicity. Indirect estimation of insulin resistance, based on insulinemia could be byassed in these patients and underestimate their type 2 diabetes mellitus risk.
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Affiliation(s)
- Blanca Guijo
- Departments of Pediatrics and Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa, Madrid, Spain
| | - Jesús Argente
- Departments of Pediatrics and Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa, Madrid, Spain
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- Instituto de alimentación IMDEA, CEIUAM+CSIC, Madrid, Spain
| | - Gabriel Ángel Martos-Moreno
- Departments of Pediatrics and Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa, Madrid, Spain
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
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Shah BP, Sleiman PM, Mc Donald J, Moeller IH, Kleyn P. Functional characterization of all missense variants in LEPR, PCSK1, and POMC genes arising from single-nucleotide variants. Expert Rev Endocrinol Metab 2023; 18:209-219. [PMID: 36864747 DOI: 10.1080/17446651.2023.2179985] [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: 12/23/2022] [Accepted: 02/09/2023] [Indexed: 02/18/2023]
Abstract
OBJECTIVE Hyperphagia and early-onset, severe obesity are clinical characteristics of rare melanocortin-4 receptor (MC4R) pathway diseases due to loss-of-function (LOF) variants in genes comprising the MC4R pathway. In vitro functional characterization of 12,879 possible exonic missense variants from single-nucleotide variants (SNVs) of LEPR, POMC, and PCSK1 was performed to determine the impact of these variants on protein function. METHODS SNVs of the three genes were transiently transfected into cell lines, and each variant was subsequently classified according to functional impact. We validated three assays by comparing classifications against functional characterization of 29 previously published variants. RESULTS Our results significantly correlated with previously published pathogenic categories (r = 0.623; P = 3.03 × 10-4) of all potential missense variants arising from SNVs. Of all observed variants identified through available databases and a tested cohort of 16,061 patients with obesity, 8.6% of LEPR, 63.2% of PCSK1, and 10.6% of POMC variants exhibited LOF, including variants currently classified as a variant of uncertain significance (VUS). CONCLUSIONS The functional data provided here can assist in the reclassification of several VUS in LEPR, PCSK1, and POMC and highlight their impact in MC4R pathway diseases.
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Affiliation(s)
- Bhavik P Shah
- Rhythm Pharmaceuticals, Inc, Boston, MA, USA
- Bridgebio Pharma, Palo Alto, CA
| | | | | | - Ida H Moeller
- Rhythm Pharmaceuticals, Inc, Boston, MA, USA
- Sarepta Therapeutics, Cambridge, MA, USA
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The genetics of monogenic intestinal epithelial disorders. Hum Genet 2022; 142:613-654. [PMID: 36422736 PMCID: PMC10182130 DOI: 10.1007/s00439-022-02501-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 10/23/2022] [Indexed: 11/27/2022]
Abstract
Monogenic intestinal epithelial disorders, also known as congenital diarrheas and enteropathies (CoDEs), are a group of rare diseases that result from mutations in genes that primarily affect intestinal epithelial cell function. Patients with CoDE disorders generally present with infantile-onset diarrhea and poor growth, and often require intensive fluid and nutritional management. CoDE disorders can be classified into several categories that relate to broad areas of epithelial function, structure, and development. The advent of accessible and low-cost genetic sequencing has accelerated discovery in the field with over 45 different genes now associated with CoDE disorders. Despite this increasing knowledge in the causal genetics of disease, the underlying cellular pathophysiology remains incompletely understood for many disorders. Consequently, clinical management options for CoDE disorders are currently limited and there is an urgent need for new and disorder-specific therapies. In this review, we provide a general overview of CoDE disorders, including a historical perspective of the field and relationship to other monogenic disorders of the intestine. We describe the genetics, clinical presentation, and known pathophysiology for specific disorders. Lastly, we describe the major challenges relating to CoDE disorders, briefly outline key areas that need further study, and provide a perspective on the future genetic and therapeutic landscape.
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Van Dijck E, Beckers S, Diels S, Huybrechts T, Verrijken A, Van Hoorenbeeck K, Verhulst S, Massa G, Van Gaal L, Van Hul W. Rare Heterozygous PCSK1 Variants in Human Obesity: The Contribution of the p.Y181H Variant and a Literature Review. Genes (Basel) 2022; 13:genes13101746. [PMID: 36292633 PMCID: PMC9601648 DOI: 10.3390/genes13101746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 09/19/2022] [Accepted: 09/19/2022] [Indexed: 11/16/2022] Open
Abstract
Recently, it was reported that heterozygous PCSK1 variants, causing partial PC1/3 deficiency, result in a significant increased risk for obesity. This effect was almost exclusively generated by the rare p.Y181H (rs145592525, GRCh38.p13 NM_000439.5:c.541T>C) variant, which affects PC1/3 maturation but not enzymatic capacity. As most of the identified individuals with the heterozygous p.Y181H variant were of Belgian origin, we performed a follow-up study in a population of 481 children and adolescents with obesity, and 486 lean individuals. We identified three obese (0.62%) and four lean (0.82%) p.Y181H carriers (p = 0.506) through sanger sequencing and high resulting melting curve analysis, indicating no association with obesity. Haplotype analysis was performed in 13 p.Y181H carriers, 20 non-carriers (10 with obesity and 10 lean), and two p.Y181H families, and showed identical haplotypes for all heterozygous carriers (p < 0.001). Likewise, state-of-the-art literature concerning the role of rare heterozygous PCSK1 variants implies them to be rarely associated with monogenic obesity, as first-degree carrier relatives of patients with PC1/3 deficiency are mostly not reported to be obese. Furthermore, recent meta-analyses have only indicated a robust association for scarce disruptive heterozygous PCSK1 variants with obesity, while clinical significance is less or sometimes lacking for most nonsynonymous variants.
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Affiliation(s)
- Evelien Van Dijck
- Centre of Medical Genetics, University of Antwerp and Antwerp University Hospital, 2650 Edegem, Belgium
| | - Sigri Beckers
- Centre of Medical Genetics, University of Antwerp and Antwerp University Hospital, 2650 Edegem, Belgium
| | - Sara Diels
- Centre of Medical Genetics, University of Antwerp and Antwerp University Hospital, 2650 Edegem, Belgium
| | - Tammy Huybrechts
- Centre of Medical Genetics, University of Antwerp and Antwerp University Hospital, 2650 Edegem, Belgium
| | - An Verrijken
- Department of Endocrinology, Diabetology and Metabolic Diseases, Antwerp University Hospital, 2650 Edegem, Belgium
| | | | - Stijn Verhulst
- Department of Pediatrics, Antwerp University Hospital, 2650 Edegem, Belgium
| | - Guy Massa
- Department of Pediatrics, Jessa Hospital, 3500 Hasselt, Belgium
| | - Luc Van Gaal
- Department of Endocrinology, Diabetology and Metabolic Diseases, Antwerp University Hospital, 2650 Edegem, Belgium
| | - Wim Van Hul
- Centre of Medical Genetics, University of Antwerp and Antwerp University Hospital, 2650 Edegem, Belgium
- Correspondence: ; Tel.: +32-759-761
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7
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Tsuzuki A, Fujioka Y, Yoshida A, Kashiwagi S, Amano M, Hira T, Nakamura A, Miyoshi H, Atsumi T, Ohba Y. Direct visualization of GLP-1 secretion by fluorescent fusion proteins. J Diabetes Investig 2022; 13:1134-1139. [PMID: 35377537 PMCID: PMC9248420 DOI: 10.1111/jdi.13800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/30/2022] [Accepted: 04/01/2022] [Indexed: 11/29/2022] Open
Abstract
Live‐cell imaging with fluorescent proteins (FPs) is a powerful tool for investigating the exocytosis processes of hormones. However, the secretion process of glucagon‐like peptide‐1 (GLP‐1) has not been visualized by FPs, which might be because tagging FPs inhibits GLP‐1 synthesis through the post‐translational processing from proglucagon. Here, we have developed FP‐tagged GLP‐1 by inserting FPs into the middle of GLP‐1 and adding the proglucagon signal peptide. Confocal imaging confirmed that GLP‐1 fused to FPs with high folding efficiency showed granular structure, in which secretory vesicle markers colocalized. The fluorescence intensity of FP in the culture supernatant from cells treated with KCl or forskolin was significantly increased compared with those from untreated cells. Furthermore, FP‐tagged GLP‐1 enables direct visualization of stimulation‐dependent exocytosis of GLP‐1 at a single granule resolution with total internal reflection fluorescence microscopy. FP‐tagged GLP‐1 might facilitate the screening of GLP‐1 secretagogues and the discovery of new antidiabetic drugs.
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Affiliation(s)
- Atsushi Tsuzuki
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.,Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yoichiro Fujioka
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.,Global Station for Biosurfaces and Drug Discovery, Hokkaido University, Sapporo, Japan
| | - Aiko Yoshida
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.,Global Station for Biosurfaces and Drug Discovery, Hokkaido University, Sapporo, Japan
| | - Sayaka Kashiwagi
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.,Global Station for Biosurfaces and Drug Discovery, Hokkaido University, Sapporo, Japan
| | - Maho Amano
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tohru Hira
- Research Group of Bioscience and Chemistry, Division of Fundamental AgriScience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Akinobu Nakamura
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hideaki Miyoshi
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.,Division of Diabetes and Obesity, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tatsuya Atsumi
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yusuke Ohba
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.,Global Station for Biosurfaces and Drug Discovery, Hokkaido University, Sapporo, Japan.,AMED- CREST, Japan Agency for Medical Research and Development, Sapporo, Japan
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Shakya M, Martin NK, Arunagiri A, Martin MG, Arvan P, Low MJ, Lindberg I. The G209R mutant mouse as a model for human PCSK1 polyendocrinopathy. Endocrinology 2022; 163:6542675. [PMID: 35245347 PMCID: PMC9044177 DOI: 10.1210/endocr/bqac024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 11/19/2022]
Abstract
PCSK1 encodes an enzyme required for prohormone maturation into bioactive peptides. A striking number of SNPs and rare mutations in PCSK1 are associated with a range of clinical phenotypes. Infants bearing two copies of a catalytically inactivating mutation, such as G209R, exhibit life-threatening chronic diarrhea and subsequently develop systemic endocrinopathies. Using CRISPR/Cas9 technology, we have engineered a mouse model bearing a G209R missense mutation in exon 6 of the murine Pcsk1 locus. Most pups homozygous for the G209R mutation succumbed by day 2, and surviving pups were severely dwarfed. In homozygous (but not heterozygous) pups, blood glucose levels were significantly lower, accompanied by elevated plasma insulin-like immunoreactivity and accumulation of large quantities of unprocessed proinsulin in the pancreas. Peptide hormone processing was also aberrant in G209R mouse pituitary, with mature ACTH levels markedly reduced in homozygotes, accompanied by a significant accumulation of POMC. We also observed a significant reduction in PC1/3 protein in the brains of G209R homozygous mice by Western blotting, while PC2 levels remained unaffected. Most likely due to the continued presence of PC2, pituitary and brain levels of α-MSH were not impaired. Analysis of intestinal cell types indicated a modest reduction of enteroendocrine cells in G209R homozygotes. We suggest that the G209R Pcsk1 mouse model recapitulates many of the dramatic neonatal deficiencies of human patients with this homozygous mutation.
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Affiliation(s)
- Manita Shakya
- Department of Anatomy & Neurobiology, University of Maryland School of
Medicine, Baltimore, MD, USA
| | - Surbhi
- Department Molecular & Integrative Physiology, University of
Michigan, Ann Arbor, MI, USA
| | - Nicolle K Martin
- Department of Pediatrics, Division of Gastroenterology and Nutrition, Mattel
Children’s Hospital and the David Geffen School of Medicine, University of California Los
Angeles, Los Angeles, CA, USA
| | - Anoop Arunagiri
- Division of Metabolism, Endocrinology & Diabetes, University of
Michigan, Ann Arbor, MI, USA
| | - Martin G Martin
- Department of Pediatrics, Division of Gastroenterology and Nutrition, Mattel
Children’s Hospital and the David Geffen School of Medicine, University of California Los
Angeles, Los Angeles, CA, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of
Michigan, Ann Arbor, MI, USA
| | - Malcolm J Low
- Department Molecular & Integrative Physiology, University of
Michigan, Ann Arbor, MI, USA
| | - Iris Lindberg
- Department of Anatomy & Neurobiology, University of Maryland School of
Medicine, Baltimore, MD, USA
- Correspondence: Iris Lindberg, PhD, Department of Anatomy and Neurobiology, University of Maryland
School of Medicine, 20 Penn St, HSF2, S218, Baltimore, MD 21201, USA.
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Ni Y, Chen X, Sun Y, Pan J, Tang C, Yuan T. Modulation of PC1/3 activity by a rare double-site homozygous mutation. Front Pediatr 2022; 10:1026707. [PMID: 36389395 PMCID: PMC9659753 DOI: 10.3389/fped.2022.1026707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/10/2022] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVES Preprotein convertase 1/3 deficiency is a rare autosomal recessive disorder in which patients present with malabsorptive diarrhea and a series of symptoms of endocrine disorders such as polydipsia, reactive hypoglycemia, growth hormone deficiency, hypothyroidism, adrenal insufficiency, and early onset obesity. In its essence, pituitary hormone deficiency is caused by insufficient cleavage of pituitary prohormones. Here, we describe a female child with a rare double-site homozygous mutation in PCSK1 (Proprotein convertase subtilisin/kexin-type 1) gene, and thereby intend to investigate the relationship between these novel mutation sites and changes in protein synthesis and function. METHODS We tested this patient's blood and urine fecal indicators of infection, blood electrolytes, and relevant endocrine hormone levels in the laboratory. Next Generation Sequencing was applied to screen the patient's DNA. Western Blot was performed to evaluate the mutant protein's expression. The enzymatic activity was measured as the rate of cleavage of a synthetic fluorogenic substrate in a specific solution. RESULTS We found that this patient presented shortly after birth with uncorrectable diarrhea and symptoms of metabolic acidosis with hypothyroidism. Next Generation Sequencing revealed that a rare double-site homozygous missense mutation, c.763G > A (p.G255R) and c.758C > T (p.S253L), were detected in exon 7 of PCSK1 (Proprotein convertase subtilisin/kexin-type 1) gene on chromosome 5 of the patient. Western blotting revealed that there was no significant decrease in protein synthesis levels in the mutant phenotype compared to the wild type. Compared with WT type, the proteins expressed by the mutations showed a significant decrease in the enzyme activity towards the fluorescent substrates. However, neither the single site mutation p.S253L or p.G255R, nor the double-site mutation of both, all showed no significant differences from each other. CONCLUSIONS These two missense mutations have not been reported before, and it is even rarer to find homozygous variation of two sites in one patient. This study identifies two novel mutations for the first time and further investigates the changes in protein synthesis and enzyme activity, providing a new pathway to continue to explore the pathogenesis of diseases associated with the function of PC1/3.
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Affiliation(s)
- Yanyan Ni
- Department of Neonatology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Xiangxiang Chen
- Department of Neonatology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yi Sun
- Department of Neonatology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Jiarong Pan
- Department of Neonatology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Chao Tang
- National Clinical Research Center for Child Health of the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Tianming Yuan
- Department of Neonatology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
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10
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Duclaux-Loras R, Bourgeois P, Lavrut PM, Charbit-Henrion F, Bonniaud-Blot P, Maudinas R, Bournez M, Faure M, Cerf-Bensussan N, Lachaux A, Peretti N, Fabre A. A novel mutation of PCSK1 responsible for PC1/3 deficiency in two siblings. Clin Res Hepatol Gastroenterol 2021; 45:101640. [PMID: 33662777 DOI: 10.1016/j.clinre.2021.101640] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 10/09/2020] [Accepted: 01/15/2021] [Indexed: 02/04/2023]
Abstract
Proprotein convertase 1 (PCSK1, PC1/3) deficiency is an uncommon cause of neonatal malabsorptive diarrhoea associated with endocrinopathies that are due to the disrupted processing of a large number of prohormones, including proinsulin. To date, only 26 cases have been reported. Herein, we describe two siblings with typical features including severe congenital diarrhoea, central diabetes insipidus, growth hormone deficiency, and hypoadrenalism. Next generation sequencing found a homozygous missense mutation in exon 5 of PCSK1 gene, c.500A>C (p.Asp167Ala), located within the catalytic domain. Both patients presented a high level of proinsulin. In the first years of life they required parenteral nutrition and hormone replacement therapy. The patients, aged 3 and 1.5 years, experienced several infectious episodes associated with septic shocks. While the mechanism underlying intestinal failure remains poorly investigated, parenteral nutrition is essential in order to ensure normal growth in early childhood.
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Affiliation(s)
- Rémi Duclaux-Loras
- Hospices Civils de Lyon, Hôpital Femme Mère Enfant, Service de Gastroentérologie, Hépathologie et Nutrition Pédiatrique, Bron, France; INSERM U1111, Centre International de Recherche en Infectiologie, Lyon, France.
| | - Patrice Bourgeois
- Aix Marseille Univ, Inserm, MMG, U1251, Marseille Medical Genetics, 13385 Marseille, France
| | - Pierre-Marie Lavrut
- Hospices Civils de Lyon, Hôpital Femme Mère Enfant, Service d'Anatomopathologie, Bron, France
| | - Fabienne Charbit-Henrion
- Service de Génétique Moléculaire, Necker-Enfants Malades Hospital, Assistance Publique des Hôpitaux de Paris, Université de Paris et Institut Imagine, Inserm UMR1163 Intestinal Immunity, Paris, France
| | | | | | | | - Mathias Faure
- INSERM U1111, Centre International de Recherche en Infectiologie, Lyon, France
| | - Nadine Cerf-Bensussan
- Université de Paris et Institut Imagine, Inserm UMR1163 Intestinal Immunity, Paris, France
| | - Alain Lachaux
- Hospices Civils de Lyon, Hôpital Femme Mère Enfant, Service de Gastroentérologie, Hépathologie et Nutrition Pédiatrique, Bron, France
| | - Noel Peretti
- Hospices Civils de Lyon, Hôpital Femme Mère Enfant, Service de Gastroentérologie, Hépathologie et Nutrition Pédiatrique, Bron, France
| | - Alexandre Fabre
- Service de Pédiatrie Multidisciplinaire, Hôpital de la Timone Enfants, APHM, 13385 Marseille, France
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Novel Homozygous Inactivating Mutation in the PCSK1 Gene in an Infant with Congenital Malabsorptive Diarrhea. Genes (Basel) 2021; 12:genes12050710. [PMID: 34068683 PMCID: PMC8151971 DOI: 10.3390/genes12050710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/02/2021] [Accepted: 05/07/2021] [Indexed: 01/03/2023] Open
Abstract
Proprotein convertase 1/3 (PC1/3), encoded by the PCSK1 gene, is expressed in neuronal and (entero)endocrine cell types, where it cleaves and hence activates a number of protein precursors that play a key role in energy homeostasis. Loss-of-function mutations in PCSK1 cause a recessive complex endocrinopathy characterized by malabsorptive diarrhea and early-onset obesity. Despite the fact that neonatal malabsorptive diarrhea is observed in all patients, it has remained understudied. The aim of this study was to investigate the enteroendocrine pathologies in a male patient with congenital PCSK1 deficiency carrying the novel homozygous c.1034A>C (p.E345A) mutation. This patient developed malabsorptive diarrhea and metabolic acidosis within the first week of life, but rapid weight gain was observed after total parenteral nutrition, and he displayed high proinsulin levels and low adrenocorticotropin. In vitro analysis showed that the p.E345A mutation in PC1/3 resulted in a (near) normal autocatalytic proPC1/3 processing and only partially impaired PC1/3 secretion, but the processing of a substrate in trans was completely blocked. Immunohistochemical staining did not reveal changes in the proGIP/GIP and proglucagon/GLP-1 ratio in colonic tissue. Hence, we report a novel PCSK1 deficient patient who, despite neonatal malabsorptive diarrhea, showed a normal morphology in the small intestine.
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12
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Ahmed ABM, Alsaleem BMR. Enteroendocrine Dysfunction in Two Saudi Sisters. Case Rep Gastroenterol 2021; 15:290-295. [PMID: 33790717 PMCID: PMC7989775 DOI: 10.1159/000511761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/18/2020] [Indexed: 12/29/2022] Open
Abstract
Proprotein convertase (PC) deficiency is a rare autosomal recessive disorder caused by mutations in proprotein convertase subtilisin/kexin type 1 (PCSK1). It is characterized by severe malabsorptive early-onset diarrhea, obesity, and systemic endocrinopathies. Only few cases have been reported in the literature; we have add two female sisters with some difference in clinical progress. Herein, we describe two sisters with congenital osmotic diarrhea diagnosed with PC1/3 deficiency, causing malabsorptive diarrhea and enteroendocrine dysfunction, who presented with chronic enteropathy with hypernatremia but with different expressivity. PC1/3 deficiency presents with symptoms and signs that mimic glucose-galactose malabsorption. Because of the clinical paucity and heterogeneity of congenital enteropathies, whole-exome sequencing may be of great help towards early diagnosis and effective treatment.
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Affiliation(s)
- Amna Basheer M Ahmed
- Department of Pediatric Gastroenterology/Hepatology, Children's Hospital, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Badr M Rasheed Alsaleem
- Department of Pediatric Gastroenterology/Hepatology, Children's Hospital, King Fahad Medical City, Riyadh, Saudi Arabia
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13
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Pépin L, Colin E, Tessarech M, Rouleau S, Bouhours-Nouet N, Bonneau D, Coutant R. A New Case of PCSK1 Pathogenic Variant With Congenital Proprotein Convertase 1/3 Deficiency and Literature Review. J Clin Endocrinol Metab 2019; 104:985-993. [PMID: 30383237 DOI: 10.1210/jc.2018-01854] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 10/26/2018] [Indexed: 01/31/2023]
Abstract
ISSUE To report a homozygous pathogenic variant in PCSK1 in a boy affected with proprotein convertase 1/3 (PC1/3) deficiency. CASE DESCRIPTION AND LITERATURE REVIEW A male infant born to consanguineous Turkish parents presented in the first week of life with transient central diabetes insipidus, watery diarrhea, micropenis due to hypogonadotropic hypogonadism and GH deficiency, and transient asymptomatic hypoglycemia. Further endocrine defects gradually appeared, including central hypothyroidism and mild central hypocortisolism (at 1 year), central diabetes insipidus that reappeared progressively (at 2.5 years), and obesity (at 2 years). Whole-exome sequencing revealed a homozygous nonsense pathogenic variant (NM_000439.4) c. 595 C>T in exon 5 of PCSK1, not yet reported in cases of PC1/3 deficiency. To date, 26 cases of PC1/3 deficiency have been reported in the literature. All individuals had early and severe malabsorptive diarrhea and 83% had polyuria-polydipsia syndrome (before 5 years). Most (79%) had early onset obesity. Various endocrine disorders were present, including GH deficiency (44%), mild central hypothyroidism (56%), central hypogonadism (44%), central hypocortisolism (57%), and postprandial hypoglycemia (52%). When described (n = 15), proinsulin levels were consistently high: between 8 and 154 times the upper limit of normal (mean 74). CONCLUSION We described a homozygous nonsense pathogenic variant (NM_000439.4) c. 595 C>T in exon 5 of PCSK1 in a boy with congenital PC1/3 deficiency. Elevated proinsulin could be useful in the diagnosis of this condition.
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Affiliation(s)
- Lucie Pépin
- Department of Pediatric Endocrinology and Diabetology, University Hospital of Angers, Angers Cedex 9, France
| | - Estelle Colin
- Department of Biochemistry and Genetics, University Hospital of Angers, Angers Cedex 9, France
- UMR CNRS 6214-INSERM 1083 and PREMMI, University of Angers, Angers Cedex 9, France
| | - Marine Tessarech
- Department of Biochemistry and Genetics, University Hospital of Angers, Angers Cedex 9, France
- UMR CNRS 6214-INSERM 1083 and PREMMI, University of Angers, Angers Cedex 9, France
| | - Stéphanie Rouleau
- Department of Pediatric Endocrinology and Diabetology, University Hospital of Angers, Angers Cedex 9, France
| | - Natacha Bouhours-Nouet
- Department of Pediatric Endocrinology and Diabetology, University Hospital of Angers, Angers Cedex 9, France
- Reference Center for Rare Diseases of Pituitary Origin-Constituent Site (HYPO), University Hospital of Angers, Angers Cedex 9, France
| | - Dominique Bonneau
- Department of Biochemistry and Genetics, University Hospital of Angers, Angers Cedex 9, France
- UMR CNRS 6214-INSERM 1083 and PREMMI, University of Angers, Angers Cedex 9, France
| | - Régis Coutant
- Department of Pediatric Endocrinology and Diabetology, University Hospital of Angers, Angers Cedex 9, France
- Reference Center for Rare Diseases of Pituitary Origin-Constituent Site (HYPO), University Hospital of Angers, Angers Cedex 9, France
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14
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Saeed S, Arslan M, Froguel P. Genetics of Obesity in Consanguineous Populations: Toward Precision Medicine and the Discovery of Novel Obesity Genes. Obesity (Silver Spring) 2018; 26:474-484. [PMID: 29464904 DOI: 10.1002/oby.22064] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 09/05/2017] [Accepted: 09/30/2017] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Consanguinity has been instrumental in the elucidation of many Mendelian genetic diseases. Here, the unique advantage of consanguineous populations was considered in the quest for genes causing obesity. METHODS PubMed was searched for articles relevant to consanguinity and obesity published between 1995 and 2016. Some earlier articles of interest were also consulted. RESULTS Although obesity is the most heritable disorder, even in outbred populations, only 2% to 5% of severe obesity cases have so far been proven to be caused by single gene mutations. In some highly consanguineous populations, a remarkably higher proportion of obesity cases because of known and novel monogenic variants has been identified (up to 30%). CONCLUSIONS Combining the power conferred by consanguinity with current large-capacity sequencing techniques should bring new genetic factors and molecular mechanisms to the fore, unveiling a large part of the yet-elusive neurohumoral circuitry involved in the regulation of energy homeostasis and appetite. Importantly, the undertaking of such initiatives is destined to unfold novel targets for the development of precision medicine relevant to different forms of obesity.
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Affiliation(s)
- Sadia Saeed
- Department of Genomics of Common Disease, Imperial College London, London, UK
- CNRS, Pasteur Institute of Lille, University of Lille, Lille, France
| | - Muhammad Arslan
- Centre for Research in Molecular Medicine, The University of Lahore, Lahore, Pakistan
- Department of Biological Sciences, Forman Christian College, Lahore, Pakistan
| | - Philippe Froguel
- Department of Genomics of Common Disease, Imperial College London, London, UK
- CNRS, Pasteur Institute of Lille, University of Lille, Lille, France
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15
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Gönç EN, Özön A, Alikaşifoğlu A, Kandemir N. Long-Term Follow-up of a Case with Proprotein Convertase 1/3 Deficiency: Transient Diabetes Mellitus with Intervening Diabetic Ketoacidosis During Growth Hormone Therapy. J Clin Res Pediatr Endocrinol 2017; 9:283-287. [PMID: 28588004 PMCID: PMC5596812 DOI: 10.4274/jcrpe.3986] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Proprotein convertase 1/3 (PC1/3) deficiency is a very rare disease characterized by severe intractable diarrhea in the first years of life, followed by obesity and several hormonal deficiencies later. Diabetes mellitus requiring insulin treatment and diabetic ketoacidosis have not been reported in this disorder. We herein present a girl with PC1/3 deficiency who has been followed from birth to 17 years of age. She developed deficiencies of all pituitary hormones over time as well as diabetes mellitus while receiving growth hormone (GH) therapy. She was complicated with diabetic ketoacidosis during dietary management of diabetes mellitus, thus insulin treatment was initiated. Insulin requirement to regulate hyperglycemia was short-lived. Repeat oral glucose tolerance test five years later was normal. The findings of this patient show that diabetes mellitus can develop at any time during follow-up of cases with proportein convertase 1/3 deficiency especially under GH therapy.
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Affiliation(s)
- E. Nazlı Gönç
- Hacettepe University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey
,* Address for Correspondence: Hacettepe University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey Phone: +90 312 305 11 24 E-mail:
| | - Alev Özön
- Hacettepe University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey
| | - Ayfer Alikaşifoğlu
- Hacettepe University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey
| | - Nurgün Kandemir
- Hacettepe University Faculty of Medicine, Department of Pediatric Endocrinology, Ankara, Turkey
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16
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Stijnen P, Ramos-Molina B, O'Rahilly S, Creemers JWM. PCSK1 Mutations and Human Endocrinopathies: From Obesity to Gastrointestinal Disorders. Endocr Rev 2016; 37:347-71. [PMID: 27187081 DOI: 10.1210/er.2015-1117] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Prohormone convertase 1/3, encoded by the PCSK1 gene, is a serine endoprotease that is involved in the processing of a variety of proneuropeptides and prohormones. Humans who are homozygous or compound heterozygous for loss-of-function mutations in PCSK1 exhibit a variable and pleiotropic syndrome consisting of some or all of the following: obesity, malabsorptive diarrhea, hypogonadotropic hypogonadism, altered thyroid and adrenal function, and impaired regulation of plasma glucose levels in association with elevated circulating proinsulin-to-insulin ratio. Recently, more common variants in the PCSK1 gene have been found to be associated with alterations in body mass index, increased circulating proinsulin levels, and defects in glucose homeostasis. This review provides an overview of the endocrinopathies and other disorders observed in prohormone convertase 1/3-deficient patients, discusses the possible biochemical basis for these manifestations of the disease, and proposes a model whereby certain missense mutations in PCSK1 may result in proteins with a dominant negative action.
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Affiliation(s)
- Pieter Stijnen
- Laboratory for Biochemical Neuroendocrinology (P.S., B.R.-M., J.W.M.C.), Department of Human Genetics, KU Leuven, Leuven 3000, Belgium; and Medical Research Council (MRC) Metabolic Diseases Unit (S.O.), Wellcome Trust-MRC Institute of Metabolic Science, National Institute for Health Research, Cambridge Biomedical Research Centre, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
| | - Bruno Ramos-Molina
- Laboratory for Biochemical Neuroendocrinology (P.S., B.R.-M., J.W.M.C.), Department of Human Genetics, KU Leuven, Leuven 3000, Belgium; and Medical Research Council (MRC) Metabolic Diseases Unit (S.O.), Wellcome Trust-MRC Institute of Metabolic Science, National Institute for Health Research, Cambridge Biomedical Research Centre, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
| | - Stephen O'Rahilly
- Laboratory for Biochemical Neuroendocrinology (P.S., B.R.-M., J.W.M.C.), Department of Human Genetics, KU Leuven, Leuven 3000, Belgium; and Medical Research Council (MRC) Metabolic Diseases Unit (S.O.), Wellcome Trust-MRC Institute of Metabolic Science, National Institute for Health Research, Cambridge Biomedical Research Centre, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
| | - John W M Creemers
- Laboratory for Biochemical Neuroendocrinology (P.S., B.R.-M., J.W.M.C.), Department of Human Genetics, KU Leuven, Leuven 3000, Belgium; and Medical Research Council (MRC) Metabolic Diseases Unit (S.O.), Wellcome Trust-MRC Institute of Metabolic Science, National Institute for Health Research, Cambridge Biomedical Research Centre, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
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17
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Early Clinical Diagnosis of PC1/3 Deficiency in a Patient With a Novel Homozygous PCSK1 Splice-Site Mutation. J Pediatr Gastroenterol Nutr 2016; 62:577-80. [PMID: 26488123 DOI: 10.1097/mpg.0000000000001018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Autosomal recessive proprotein convertase 1/3 (PC1/3) deficiency, caused by mutations in the PCSK1 gene, is characterized by severe congenital malabsorptive diarrhea, early-onset obesity, and certain endocrine abnormalities. We suspected PC1/3 deficiency in a 4-month-old girl based on the presence of congenital diarrhea and polyuria. Sequencing the whole coding region and splice sites detected a novel homozygous PCSK1 splice-site mutation, c.544-2A>G, in the patient. The mutation resulted in the skipping of exon 5, the generation of a premature termination codon, and nonsense-mediated PCSK1 messenger ribonucleic acid decay, which was demonstrated in complementary DNA derived from fibroblasts.
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18
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Ramos-Molina B, Martin MG, Lindberg I. PCSK1 Variants and Human Obesity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 140:47-74. [PMID: 27288825 DOI: 10.1016/bs.pmbts.2015.12.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PCSK1, encoding prohormone convertase 1/3 (PC1/3), was one of the first genes linked to monogenic early-onset obesity. PC1/3 is a protease involved in the biosynthetic processing of a variety of neuropeptides and prohormones in endocrine tissues. PC1/3 activity is essential for the activating cleavage of many peptide hormone precursors implicated in the regulation of food ingestion, glucose homeostasis, and energy homeostasis, for example, proopiomelanocortin, proinsulin, proglucagon, and proghrelin. A large number of genome-wide association studies in a variety of different populations have now firmly established a link between three PCSK1 polymorphisms frequent in the population and increased risk of obesity. Human subjects with PC1/3 deficiency, a rare autosomal-recessive disorder caused by the presence of loss-of-function mutations in both alleles, are obese and display a complex set of endocrinopathies. Increasing numbers of genetic diagnoses of infants with persistent diarrhea has recently led to the finding of many novel PCSK1 mutations. PCSK1-deficient infants experience severe intestinal malabsorption during the first years of life, requiring controlled nutrition; these children then become hyperphagic, with associated obesity. The biochemical characterization of novel loss-of-function PCSK1 mutations has resulted in the discovery of new pathological mechanisms affecting the cell biology of the endocrine cell beyond simple loss of enzyme activity, for example, dominant-negative effects of certain mutants on wild-type PC1/3 protein, and activation of the cellular unfolded protein response by endoplasmic reticulum-retained mutants. A better understanding of these molecular and cellular pathologies may illuminate possible treatments for the complex endocrinopathy of PCSK1 deficiency, including obesity.
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Affiliation(s)
- B Ramos-Molina
- Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - M G Martin
- Department of Pediatrics, Division of Gastroenterology and Nutrition, Mattel Children's Hospital and the David Geffen School of Medicine, Los Angeles, CA, United States of America
| | - I Lindberg
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, MD, United States of America.
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19
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Stijnen P, Brouwers B, Dirkx E, Ramos-Molina B, Van Lommel L, Schuit F, Thorrez L, Declercq J, Creemers JWM. Endoplasmic reticulum-associated degradation of the mouse PC1/3-N222D hypomorph and human PCSK1 mutations contributes to obesity. Int J Obes (Lond) 2016; 40:973-81. [PMID: 26786350 DOI: 10.1038/ijo.2016.3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 12/03/2015] [Accepted: 12/22/2015] [Indexed: 12/26/2022]
Abstract
BACKGROUND The proprotein convertase 1/3 (PC1/3), encoded by proprotein convertase subtilisin/kexin type 1 (PCSK1), cleaves and hence activates several orexigenic and anorexigenic proproteins. Congenital inactivation of PCSK1 leads to obesity in human but not in mice. However, a mouse model harboring the hypomorphic mutation N222D is obese. It is not clear why the mouse models differ in phenotype. METHODS Gene expression analysis was performed with pancreatic islets from Pcsk1(N222D/N222D) mice. Subsequently, biosynthesis, maturation, degradation and activity were studied in islets, pituitary, hypothalamus and cell lines. Coimmunoprecipitation of PC1/3-N222D and human PC1/3 variants associated with obesity with the endoplasmic reticulum (ER) chaperone BiP was studied in cell lines. RESULTS Gene expression analysis of islets of Pcsk1(N222D/N222D) mice showed enrichment of gene sets related to the proteasome and the unfolded protein response. Steady-state levels of PC1/3-N222D and in particular the carboxy-terminally processed form were strongly reduced in islets, pituitary and hypothalamus. However, impairment of substrate cleavage was tissue dependent. Proinsulin processing was drastically reduced, while processing of proopiomelanocortin (POMC) to adrenocorticotropic hormone (ACTH) in pituitary was only mildly impaired. Growth hormone expression and IGF-1 levels were normal, indicating near-normal processing of hypothalamic proGHRH. PC1/3-N222D binds to BiP and is rapidly degraded by the proteasome. Analysis of human PC1/3 obesity-associated mutations showed increased binding to BiP and prolonged intracellular retention for all investigated mutations, in particular for PC1/3-T175M, PC1/3-G226R and PC1/3-G593R. CONCLUSIONS This study demonstrates that the hypomorphic mutation in Pcsk1(N222D) mice has an effect on catalytic activity in pancreatic islets, pituitary and hypothalamus. Reduced substrate processing activity in Pcsk1(N222D/N222D) mice is due to enhanced degradation in addition to reduced catalytic activity of the mutant. PC1/3-N222D binds to BiP, suggesting impaired folding and reduced stability. Enhanced BiP binding is also observed in several human obesity-associated PC1/3 variants, suggesting a common mechanism.
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Affiliation(s)
- P Stijnen
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - B Brouwers
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - E Dirkx
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - B Ramos-Molina
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - L Van Lommel
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - F Schuit
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - L Thorrez
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - J Declercq
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - J W M Creemers
- Laboratory for Biochemical Neuroendocrinology, Department of Human Genetics, KU Leuven, Leuven, Belgium
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20
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Blanco EH, Ramos-Molina B, Lindberg I. Revisiting PC1/3 Mutants: Dominant-Negative Effect of Endoplasmic Reticulum-Retained Mutants. Endocrinology 2015; 156. [PMID: 26207343 PMCID: PMC4588832 DOI: 10.1210/en.2015-1068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Prohormone convertase 1/3 (PC1/3), encoded by the gene PCSK1, is critical for peptide hormone synthesis. An increasing number of studies have shown that inactivating mutations in PCSK1 are correlated with endocrine pathologies ranging from intestinal dysfunction to morbid obesity, whereas the common nonsynonymous polymorphisms rs6232 (N221D) and rs6234-rs6235 (Q665E-S690T) are highly associated with obesity risk. In this report, we revisited the biochemical and cellular properties of PC1/3 variants in the context of a wild-type PC1/3 background instead of the S357G hypermorph background used for all previous studies. In the wild-type background the PC1/3 N221D variant exhibited 30% lower enzymatic activity in a fluorogenic assay than wild-type PC1/3; this inhibition was greater than that detected in an equivalent experiment using the PC1/3 S357G background. A PC1/3 variant with the linked carboxyl-terminal polymorphisms Q665E-S690T did not show this difference. We also analyzed the biochemical properties of 2 PC1/3 mutants, G209R and G593R, which are retained in the endoplasmic reticulum (ER), and studied their effects on wild-type PC1/3. The expression of ER-retained mutants induced ER stress markers and also resulted in dominant-negative blockade of wild-type PC1/3 prodomain cleavage and decreased expression of wild-type PC1/3, suggesting facilitation of the entry of wild-type protein to a degradative proteasomal pathway. Dominant-negative effects of PC1/3 mutations on the expression and maturation of wild-type protein, with consequential effects on PC1/3 availability, add a new element which must be considered in population and clinical studies of this gene.
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Affiliation(s)
- Elias H Blanco
- Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Bruno Ramos-Molina
- Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
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