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Abstract
Pseudohypoparathyroidism (PHP) refers to a heterogeneous group of uncommon, yet related metabolic disorders that are characterized by impaired activation of the Gsα/cAMP/PKA signaling pathway by parathyroid hormone (PTH) and other hormones that interact with Gsa-coupled receptors. Proximal renal tubular resistance to PTH and thus hypocalcemia and hyperphosphatemia, frequently in presence of brachydactyly, ectopic ossification, early-onset obesity, or short stature are common features of PHP. Registries and large cohorts of patients are needed to conduct clinical and genetic research, to improve the still limited knowledge regarding the underlying disease mechanisms, and allow the development of novel therapies.
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Affiliation(s)
- Agnès Linglart
- INSERM-U1185, Paris Sud Paris-Saclay University, Bicêtre Paris Sud Hospital, 64 Gabriel Péri Street, 94270 Le Kremlin Bicêtre, France; APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Network OSCAR and 'Platform of Expertise Paris Sud for Rare Diseases, Bicêtre Paris Sud Hospital, 64 Gabriel Péri Street, 94270 Le Kremlin Bicêtre, France; APHP, Endocrinology and Diabetes for Children, Bicêtre Paris Sud Hospital, 64 Gabriel Péri Street, 94270 Le Kremlin Bicêtre, France.
| | - Michael A Levine
- Division of Endocrinology and Diabetes, Center for Bone Health, The Children's Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Pediatrics, University of Pennsylvania Perelman, School of Medicine, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, 50 Blossom street, Boston, MA 02114, USA; Pediatric Nephrology Unit, Massachusetts General Hospital, Harvard Medical School, 50 Blossom street, Boston, MA 02114, USA
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Guerreiro R, Brás J, Batista S, Pires P, Ribeiro MH, Almeida MR, Oliveira C, Hardy J, Santana I. Pseudohypoparathyroidism type I-b with neurological involvement is associated with a homozygous PTH1R mutation. GENES, BRAIN, AND BEHAVIOR 2016; 15:669-77. [PMID: 27415614 PMCID: PMC5026059 DOI: 10.1111/gbb.12308] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 07/11/2016] [Accepted: 07/11/2016] [Indexed: 12/16/2022]
Abstract
Pseudohypoparathyroidism type 1b (PHP1b) is characterized by hypocalcemia, hyperphosphatemia, increased levels of circulating parathyroid hormone (PTH), and no skeletal or developmental abnormalities. The goal of this study was to perform a full characterization of a familial case of PHP1b with neurological involvement and to identify the genetic cause of disease. The initial laboratory profile of the proband showed severe hypocalcemia, hyperphosphatemia and normal levels of PTH, which was considered to be compatible with primary hypoparathyroidism. With disease progression the patient developed cognitive disturbance, PTH levels were found to be slightly elevated and a picture of PTH resistance syndrome seemed more probable. The diagnosis of PHP1b was established after the study of family members and blunted urinary cAMP results were obtained in a PTH stimulation test. Integration of whole genome genotyping and exome sequencing data supported this diagnosis by revealing a novel homozygous missense mutation in PTH1R (p.Arg186His) completely segregating with the disease. Here, we demonstrate segregation of a novel mutation in PTH1R with a phenotype of PHP1b presenting with neurological symptoms, but no bone defects. This case represents the extreme end of the spectrum of cognitive impairment in PTH dysfunction and defines a possible novel form of PHP1b resulting from the impaired interaction between PTH and PTH1R.
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Affiliation(s)
- R Guerreiro
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK.
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal.
| | - J Brás
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - S Batista
- Neurology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - P Pires
- Hospital do Santo Espírito, Terceira, Portugal
| | - M H Ribeiro
- CNC - Center for Neuroscience and Cell Biology
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - M R Almeida
- CNC - Center for Neuroscience and Cell Biology
| | - C Oliveira
- CNC - Center for Neuroscience and Cell Biology
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - J Hardy
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - I Santana
- Neurology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
- CNC - Center for Neuroscience and Cell Biology
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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Guo J, Song L, Liu M, Segawa H, Miyamoto KI, Bringhurst FR, Kronenberg HM, Jüppner H. Activation of a non-cAMP/PKA signaling pathway downstream of the PTH/PTHrP receptor is essential for a sustained hypophosphatemic response to PTH infusion in male mice. Endocrinology 2013; 154:1680-9. [PMID: 23515284 PMCID: PMC3628020 DOI: 10.1210/en.2012-2240] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PTH increases urinary Pi excretion by reducing expression of two renal cotransporters [NaPi-IIa (Npt2a) and NaPi-IIc (Npt2c)]. In contrast to acute transporter regulation that is cAMP/protein kinase A dependent, long-term effects require phospholipase C (PLC) signaling by the PTH/PTHrP receptor (PPR). To determine whether the latter pathway regulates Pi through Npt2a and/or Npt2c, wild-type mice (Wt) and animals expressing a mutant PPR incapable of PLC activation (DD) were tested in the absence of one (Npt2a(-/-) or Npt2c(-/-)) or both phosphate transporters (2a/2c-dko). PTH infusion for 8 days caused a rapid and persistent decrease in serum Pi in Wt mice, whereas serum Pi in DD mice fell only transiently for the first 2 days. Consistent with these findings, fractional Pi excretion index was increased initially in both animals, but this increase persisted only when the PPR Wt was present. The hypophosphatemic response to PTH infusion was impaired only slightly in PPR Wt/Npt2c(-/-) or DD/Npt2c(-/-) mice. Despite lower baselines, PTH infusion in PPR Wt/Npt2a(-/-) mice decreased serum Pi further, an effect that was attenuated in DD/Npt2a(-/-) mice. Continuous PTH had no effect on serum Pi in 2a/2c-dko mice. PTH administration increased serum 1,25 dihydroxyvitamin D3 levels in Wt and DD mice and increased levels above the elevated baseline with ablation of either but not of both transporters. Continuous PTH elevated serum fibroblast growth factor 23 and blood Ca(2+) equivalently in all groups of mice. Our data indicate that PLC signaling at the PPR contributes to the long-term effect of PTH on Pi homeostasis but not to the regulation of 1,25 dihydroxyvitamin D3, fibroblast growth factor 23, or blood Ca(2+).
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MESH Headings
- Animals
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Hypophosphatemia/chemically induced
- Hypophosphatemia/genetics
- Hypophosphatemia/metabolism
- Infusions, Intravenous
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mutation/physiology
- Parathyroid Hormone/administration & dosage
- Parathyroid Hormone/adverse effects
- Parathyroid Hormone/metabolism
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Receptor, Parathyroid Hormone, Type 1/physiology
- Signal Transduction/genetics
- Signal Transduction/physiology
- Sodium-Phosphate Cotransporter Proteins, Type IIa/genetics
- Sodium-Phosphate Cotransporter Proteins, Type IIa/metabolism
- Sodium-Phosphate Cotransporter Proteins, Type IIc/genetics
- Sodium-Phosphate Cotransporter Proteins, Type IIc/metabolism
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Affiliation(s)
- Jun Guo
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Sanchez J, Perera E, Jan de Beur S, Ding C, Dang A, Berkovitz GD, Levine MA. Madelung-like deformity in pseudohypoparathyroidism type 1b. J Clin Endocrinol Metab 2011; 96:E1507-11. [PMID: 21752878 PMCID: PMC3167675 DOI: 10.1210/jc.2011-1411] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 06/24/2011] [Indexed: 01/14/2023]
Abstract
CONTEXT Pseudohypoparathyroidism (PHP) types 1a and 1b are distinguished by clinical, biochemical, and molecular features. We report extended kindred with PHP 1b in which many affected members also had growth plate defects, including brachydactyly and a Madelung-like deformity. DESIGN Analyses included clinical examination, assessment of mineral metabolism, thyroid function, skeletal radiography, and analysis of the GNAS and STX16 genes. SETTING Patients were studied in an academic medical center. RESULTS We studied 37 members of a family in which PHP 1b occurred in 23 individuals. Ten of 17 affected patients who were examined had brachydactyly E, including two subjects with Madelung-like defects. Five of 16 subjects had subclinical hypothyroidism; no subject showed sc ossification or short stature. None of the unaffected members had brachydactyly or an elevated serum level of PTH or TSH. Levels of immunoactive erythrocyte Gα(s) were normal in two affected subjects tested. Linkage analysis indicated linkage between PTH resistance and the GNAS gene locus; however, no mutations were identified in GNAS exons 1-13. Methylation analysis of genomic DNA from affected subjects showed loss of maternal epigenotype in exon 1A with normal methylation of the differentially methylated regions for XLGαs and NESP55, and PCR demonstrated heterozygosity for a 3.0-kb deletion in the STX16 gene. CONCLUSION The segregation of brachydactyly with PHP 1b in this family indicates that an imprinting defect in GNAS can lead to growth plate defects, including brachydactyly and Madelung deformity. These features suggest that GNAS signaling plays a more extensive role in chondrocyte maturation than previously thought.
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Affiliation(s)
- Janine Sanchez
- Division of Pediatric Endocrinology, MCCD 3044A, D820, 1601 NW 12th Avenue, Miami, Florida 33136.
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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.
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Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Clemens TL, Cormier S, Eichinger A, Endlich K, Fiaschi-Taesch N, Fischer E, Friedman PA, Karaplis AC, Massfelder T, Rossert J, Schlüter KD, Silve C, Stewart AF, Takane K, Helwig JJ. Parathyroid hormone-related protein and its receptors: nuclear functions and roles in the renal and cardiovascular systems, the placental trophoblasts and the pancreatic islets. Br J Pharmacol 2001; 134:1113-36. [PMID: 11704631 PMCID: PMC1573066 DOI: 10.1038/sj.bjp.0704378] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2001] [Accepted: 09/10/2001] [Indexed: 11/09/2022] Open
Abstract
The cloning of the so-called 'parathyroid hormone-related protein' (PTHrP) in 1987 was the result of a long quest for the factor which, by mimicking the actions of PTH in bone and kidney, is responsible for the hypercalcemic paraneoplastic syndrome, humoral calcemia of malignancy. PTHrP is distinct from PTH in a number of ways. First, PTHrP is the product of a separate gene. Second, with the exception of a short N-terminal region, the structure of PTHrP is not closely related to that of PTH. Third, in contrast to PTH, PTHrP is a paracrine factor expressed throughout the body. Finally, most of the functions of PTHrP have nothing in common with those of PTH. PTHrP is a poly-hormone which comprises a family of distinct peptide hormones arising from post-translational endoproteolytic cleavage of the initial PTHrP translation products. Mature N-terminal, mid-region and C-terminal secretory forms of PTHrP are thus generated, each of them having their own physiologic functions and probably their own receptors. The type 1 PTHrP receptor, binding both PTH(1-34) and PTHrP(1-36), is the only cloned receptor so far. PTHrP is a PTH-like calciotropic hormone, a myorelaxant, a growth factor and a developmental regulatory molecule. The present review reports recent aspects of PTHrP pharmacology and physiology, including: (a) the identification of new peptides and receptors of the PTH/PTHrP system; (b) the recently discovered nuclear functions of PTHrP and the role of PTHrP as an intracrine regulator of cell growth and cell death; (c) the physiological and developmental actions of PTHrP in the cardiovascular and the renal glomerulo-vascular systems; (d) the role of PTHrP as a regulator of pancreatic beta cell growth and functions, and, (e) the interactions of PTHrP and calcium-sensing receptors for the control of the growth of placental trophoblasts. These new advances have contributed to a better understanding of the pathophysiological role of PTHrP, and will help to identify its therapeutic potential in a number of diseases.
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Affiliation(s)
- Thomas L Clemens
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio, U.S.A
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio, U.S.A
| | - Sarah Cormier
- INSERM U 426 and Institut Federatif de Recherche ‘Cellules Epitheliales', Faculte de Medecine Xavier Bichat, Paris, France
| | - Anne Eichinger
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
| | - Karlhans Endlich
- Institut für Anatomie und Zellbiologie 1, Universität Heidelberg, Heidelberg, Germany
| | - Nathalie Fiaschi-Taesch
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, U.S.A
| | - Evelyne Fischer
- Department of Nephrology, University Hospital of Strasbourg, Strasbourg, France
| | - Peter A Friedman
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, U.S.A
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, U.S.A
| | | | - Thierry Massfelder
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
| | - Jérôme Rossert
- INSERM U489 and Departments of Nephrology and Pathology, Paris VI University, France
| | | | - Caroline Silve
- INSERM U 426 and Institut Federatif de Recherche ‘Cellules Epitheliales', Faculte de Medecine Xavier Bichat, Paris, France
| | - Andrew F Stewart
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, U.S.A
| | - Karen Takane
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, PA 15213, U.S.A
| | - Jean-Jacques Helwig
- Section of Renovascular Pharmacology and Physiology, INSERM E0015-ULP, University Louis Pasteur School of Medicine, Strasbourg, France
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