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Garin I, Mantovani G, Aguirre U, Barlier A, Brix B, Elli FM, Freson K, Grybek V, Izzi B, Linglart A, de Nanclares GP, Silve C, Thiele S, Werner R. European guidance for the molecular diagnosis of pseudohypoparathyroidism not caused by point genetic variants at GNAS: an EQA study. Eur J Hum Genet 2015; 23:560. [PMID: 25762030 DOI: 10.1038/ejhg.2015.40] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Silve C. Acrodysostosis: A new form of pseudohypoparathyroidism? ANNALES D'ENDOCRINOLOGIE 2015; 76:110-2. [DOI: 10.1016/j.ando.2015.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 03/05/2015] [Indexed: 12/21/2022]
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Linglart A, Silve C, Rothenbuhler A. Multiple hormonal resistances: Diagnosis, evaluation and therapy. ANNALES D'ENDOCRINOLOGIE 2015; 76:98-100. [DOI: 10.1016/j.ando.2015.03.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 03/11/2015] [Indexed: 10/23/2022]
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Garin I, Elli FM, Linglart A, Silve C, de Sanctis L, Bordogna P, Pereda A, Clarke JTR, Kannengiesser C, Coutant R, Tenebaum-Rakover Y, Admoni O, de Nanclares GP, Mantovani G. Novel microdeletions affecting the GNAS locus in pseudohypoparathyroidism: characterization of the underlying mechanisms. J Clin Endocrinol Metab 2015; 100:E681-7. [PMID: 25594858 DOI: 10.1210/jc.2014-3098] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
CONTEXT Pseudohypoparathyroidism type Ia (PHP1A) is a rare endocrine disorder characterized by hypocalcemia, hyperphosphatemia, multiple hormonal resistance, and features of Albright hereditary osteodystrophy. When the phenotype is present but not associated with hormonal resistance, it is called psedopseudohypoparathyroidism (PPHP). Both entities have been associated to GNAS haploinsufficiency, and are mostly caused by inherited inactivating mutations at GNAS gene that codes for the stimulatory alpha subunit of G protein, although the cause remains unidentified in approximately 30% of patients. OBJECTIVES The aims of our work were 1) to identify GNAS locus defects in 112 patients with clinical diagnosis of PHP1A/PPHP and no point mutations at GNAS, to improve molecular diagnostic and genetic counseling; 2) to outline the underlying molecular mechanism(s). METHODS Methylation-specific-multiplex ligation-dependent probe amplification, qPCR, array comparative genomic hybridization, and long-PCR were used to search for genomic rearrangements at chromosome 20q and to identify their boundaries. We used different bioinformatic approaches to assess the involvement of the genomic architecture in the origin of the deletions. RESULTS We discovered seven novel genomic deletions, ranging from 106-bp to 2.6-Mb. The characterization of five of seven deletion breakpoints and the definition of the putative molecular mechanisms responsible for these rearrangements revealed that Alu sequences play a major role in determining the genetic instability of the region. CONCLUSION We observed that deletions at GNAS locus represent a significant cause of PPHP/PHP1A and that such defects are mostly associated with Alu-mediated recombination events. Their investigation revealed to be fundamental as, in some cases, they could be misdiagnosed as imprinting defects.
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Grybek V, Aubry L, Maupetit-Méhouas S, Le Stunff C, Denis C, Girard M, Linglart A, Silve C. Methylation and transcripts expression at the imprinted GNAS locus in human embryonic and induced pluripotent stem cells and their derivatives. Stem Cell Reports 2014; 3:432-43. [PMID: 25241742 PMCID: PMC4266011 DOI: 10.1016/j.stemcr.2014.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 02/06/2023] Open
Abstract
Data from the literature indicate that genomic imprint marks are disturbed in human pluripotent stem cells (PSCs). GNAS is an imprinted locus that produces one biallelic (Gsα) and four monoallelic (NESP55, GNAS-AS1, XLsα, and A/B) transcripts due to differential methylation of their promoters (DMR). To document imprinting at the GNAS locus in PSCs, we studied GNAS locus DMR methylation and transcript (NESP55, XLsα, and A/B) expression in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) derived from two human fibroblasts and their progenies. Results showed that (1) methylation at the GNAS locus DMRs is DMR and cell line specific, (2) changes in allelic transcript expression can be independent of a change in allele-specific DNA methylation, and (3) interestingly, methylation at A/B DMR is correlated with A/B transcript expression. These results indicate that these models are valuable to study the mechanisms controlling GNAS methylation, factors involved in transcript expression, and possibly mechanisms involved in the pathophysiology of pseudohypoparathyroidism type 1B. GNAS locus methylation is DMR and cell line specific in human pluripotent stem cells Allelic transcript expression can be independent of allele-specific DNA methylation A/B transcript expression, a key for PHP1B, is correlated with A/B DMR methylation
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Lambert AS, Grybek V, Francou B, Esterle L, Bertrand G, Bouligand J, Guiochon-Mantel A, Hieronimus S, Voitel D, Soskin S, Magdelaine C, Lienhardt A, Silve C, Linglart A. Analysis of AP2S1, a calcium-sensing receptor regulator, in familial and sporadic isolated hypoparathyroidism. J Clin Endocrinol Metab 2014; 99:E469-73. [PMID: 24423332 DOI: 10.1210/jc.2013-3136] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND Except after neck surgery, hypoparathyroidism is a rare disease caused by defects in genes involved in parathyroid gland development (TBX1/22q11.2 del, GCMB, GATA3, TBCE) or function [calcium sensing receptor (CASR), GNA11, PTH], or the autoimmune polyglandular syndrome type 1 (AIRE). Approximately 90% of sporadic cases and 30% of familial cases of isolated hypoparathyroidism remain unexplained. Recurrent missense mutations in AP2S1, a calcium-sensing receptor regulator, have been recently identified in familial hyperparathyroidism. AIM The aim of the study was to investigate AP2S1 as a putative hypoparathyroidism-causing gene. METHODS Sequencing analysis and quantitative genomic PCR of the AP2S1 gene in a large cohort of 10 index cases (from nine families) and 50 sporadic cases affected with isolated hypoparathyroidism were investigated. RESULTS AND CONCLUSIONS None of the 60 patients presented with nucleotidic changes or copy number variation in the AP2S1 gene, thereby excluding AP2S1 defects as a frequent cause of isolated hypoparathyroidism.
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Mantovani G, Linglart A, Garin I, Silve C, Elli FM, de Nanclares GP. Clinical utility gene card for: pseudohypoparathyroidism. Eur J Hum Genet 2013; 21:ejhg2012211. [PMID: 22968134 PMCID: PMC3658187 DOI: 10.1038/ejhg.2012.211] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Maupetit-Méhouas S, Azzi S, Steunou V, Sakakini N, Silve C, Reynes C, Perez de Nanclares G, Keren B, Chantot S, Barlier A, Linglart A, Netchine I. Simultaneous Hyper- and Hypomethylation at Imprinted Loci in a Subset of Patients withGNASEpimutations Underlies a Complex and Different Mechanism of Multilocus Methylation Defect in Pseudohypoparathyroidism Type 1b. Hum Mutat 2013; 34:1172-80. [DOI: 10.1002/humu.22352] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/29/2013] [Indexed: 12/31/2022]
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Bricaire L, Odou MF, Cardot-Bauters C, Delemer B, North MO, Salenave S, Vezzosi D, Kuhn JM, Murat A, Caron P, Sadoul JL, Silve C, Chanson P, Barlier A, Clauser E, Porchet N, Groussin L. Frequent large germline HRPT2 deletions in a French National cohort of patients with primary hyperparathyroidism. J Clin Endocrinol Metab 2013; 98:E403-8. [PMID: 23293331 DOI: 10.1210/jc.2012-2789] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
CONTEXT Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is an autosomal dominant syndrome with incomplete penetrance that can associate in a single patient parathyroid adenoma or carcinoma, fibro-osseous jaw tumor, cystic kidney lesion, and uterine tumor. Germline mutations of the HRPT2 gene (CDC73) coding for parafibromin are identified in approximately 50%-75% of HPT-JT cases and in approximately 14% of familial isolated hyperparathyroidism. A whole deletion of this gene has recently been reported in 1 sporadic case and in a family presenting with HPT-JT. OBJECTIVE The objective of the study was to report molecular abnormalities of the HRPT2 gene in patients with primary hyperparathyroidism in a French National cohort from the Groupe d'Étude des Tumeurs Endocrines. METHODS Patients' genomic DNA was screened by PCR-based sequencing for point mutations affecting HRPT2 and real-time quantitative PCR analysis for gross deletions. RESULTS We report 20 index patients with a germinal HRPT2 abnormality. Median age at diagnosis of primary hyperparathyroidism was 23 years (range 14-65 years). Median serum total calcium level at diagnosis was 3.19 mmol/L (range 2.8-4.3 mmol/L). Thirteen different mutations were identified by routine sequencing, including 7 mutations never reported. Seven patients (35%) carried a gross deletion of this gene (3 complete and 4 partial deletions). No genotype-phenotype correlation could be identified. A gross deletion of the HRPT2 gene was identified in 7% of patients for whom a routine screening by direct sequencing came up as negative. CONCLUSION Gross deletion analysis of the HRPT2 gene is indicated for all patients negative for mutation, presenting with HPT-JT or familial isolated hyperparathyroidism, parathyroid carcinoma, or in patients with apparently sporadic parathyroid adenoma diagnosed at a young age, having a severe hypercalcemia.
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Linglart A, Fryssira H, Hiort O, Holterhus PM, Perez de Nanclares G, Argente J, Heinrichs C, Kuechler A, Mantovani G, Leheup B, Wicart P, Chassot V, Schmidt D, Rubio-Cabezas Ó, Richter-Unruh A, Berrade S, Pereda A, Boros E, Muñoz-Calvo MT, Castori M, Gunes Y, Bertrand G, Bougnères P, Clauser E, Silve C. PRKAR1A and PDE4D mutations cause acrodysostosis but two distinct syndromes with or without GPCR-signaling hormone resistance. J Clin Endocrinol Metab 2012; 97:E2328-38. [PMID: 23043190 DOI: 10.1210/jc.2012-2326] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
CONTEXT Acrodysostosis is a rare skeletal dysplasia that is associated with multiple resistance to G protein-coupled receptor (GPCR) signaling hormones in a subset of patients. Acrodysostosis is genetically heterogeneous because it results from heterozygous mutations in PRKAR1A or PDE4D, two key actors in the GPCR-cAMP-protein kinase A pathway. OBJECTIVE Our objective was to identify the phenotypic features that distinguish the two genotypes causing acrodysostosis. PATIENTS AND METHODS Sixteen unrelated patients with acrodysostosis underwent a candidate-gene approach and were investigated for phenotypic features. RESULTS All patients had heterozygous de novo mutations. Fourteen patients carried a PRKAR1A mutation (PRKAR1A patients), five each a novel PRKAR1A mutation (p.Q285R, p.G289E, p.A328V, p.R335L, or p.Q372X), nine the reported PRKAR1A p.R368X mutation; two patients harbored a mutation in PDE4D (PDE4D patients) (one novel mutation, p.A227S; one reported, p.E590A). All PRKAR1A, but none of the PDE4D mutated patients were resistant to PTH and TSH. Two PRKAR1A patients each with a novel mutation presented a specific pattern of brachydactyly. One PDE4D patient presented with acroskyphodysplasia. Additional phenotypic differences included mental retardation in PDE4D patients. In addition, we report the presence of pigmented skin lesions in PRKAR1A and PDE4D patients, a feature not yet described in the acrodysostosis entity. CONCLUSIONS All PRKAR1A and PDE4D patients present similar bone dysplasia characterizing acrodysostosis. Phenotypic differences, including the presence of resistance to GPCR-cAMP signaling hormones in PRKAR1A but not PDE4D patients, indicate phenotype-genotype correlations and highlight the specific contributions of PRKAR1A and PDE4D in cAMP signaling in different tissues.
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Abstract
Acrodysostosis refers to a group of rare skeletal dysplasias that share in common characteristic clinical and radiological features including brachydactyly, facial dysostosis, and nasal hypoplasia. In the past, the term acrodysostosis has been used to describe patients with heterogeneous phenotypes, including, in some cases, patients that today would be given alternative diagnoses. The recent finding that mutations impairing the cAMP binding to PRKAR1A are associated with "typical" acrodysostosis and hormonal resistance initiates the era where this group of disorders can be categorized on a genetic basis. In this review, we will first discuss the clinical, radiologic, and metabolic features of acrodysostosis, emphasizing evidence that several forms of the disease are likely to exist. Second, we will describe recent results explaining the pathogenesis of acrodysostosis with hormonal resistance (ADOHR). Finally, we will discuss the similarities and differences observed comparing patients with ADOHR and other diseases resulting from defects in the PTHR1 signaling pathway, in particular, pseudohypoparathyroidism type 1a and pseudopseudohypoparathyroidism.
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Linglart A, Rothenbuhler A, Gueorgieva I, Lucchini P, Silve C, Bougnères P. Long-term results of continuous subcutaneous recombinant PTH (1-34) infusion in children with refractory hypoparathyroidism. J Clin Endocrinol Metab 2011; 96:3308-12. [PMID: 21865375 DOI: 10.1210/jc.2011-1359] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hypoparathyroidism in children is most often due to mutations in genes involved in parathyroid development and calcium homeostasis signaling. Some rare cases result from autoimmune attack on the parathyroid glands as a part of the type 1 polyglandular failure syndrome (autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy). The majority of cases of pediatric hypoparathyroidism are well controlled under conventional treatment with calcium and vitamin D analogs. However, this treatment may be difficult to manage, especially in two situations: 1) in the context of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy and 2) activating mutations in the calcium-sensing receptor. We successfully treated three patients with hypoparathyroidism with continuous subcutaneous administration of rhPTH(1-34) (recombinant human PTH(1-34)), two of which were refractory to conventional therapy.
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Linglart A, Menguy C, Couvineau A, Auzan C, Gunes Y, Cancel M, Motte E, Pinto G, Chanson P, Bougnères P, Clauser E, Silve C. Recurrent PRKAR1A mutation in acrodysostosis with hormone resistance. N Engl J Med 2011; 364:2218-26. [PMID: 21651393 DOI: 10.1056/nejmoa1012717] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The skeletal dysplasia characteristic of acrodysostosis resembles the Albright's hereditary osteodystrophy seen in patients with pseudohypoparathyroidism type 1a, but defects in the α-stimulatory subunit of the G-protein (GNAS), the cause of pseudohypoparathyroidism type 1a, are not present in patients with acrodysostosis. We report a germ-line mutation in the gene encoding PRKAR1A, the cyclic AMP (cAMP)-dependent regulatory subunit of protein kinase A, in three unrelated patients with acrodysostosis and resistance to multiple hormones. The mutated subunit impairs the protein kinase A response to stimulation by cAMP; this explains our patients' hormone resistance and the similarities of their skeletal abnormalities with those observed in patients with pseudohypoparathyroidism type 1a.
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Maupetit-Méhouas S, Mariot V, Reynès C, Bertrand G, Feillet F, Carel JC, Simon D, Bihan H, Gajdos V, Devouge E, Shenoy S, Agbo-Kpati P, Ronan A, Naud-Saudreau C, Lienhardt A, Silve C, Linglart A. Quantification of the methylation at the GNAS locus identifies subtypes of sporadic pseudohypoparathyroidism type Ib. J Med Genet 2011; 48:55-63. [PMID: 20972248 DOI: 10.1136/jmg.2010.081356] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Pseudohypoparathyroidism type Ib (PHP-Ib) is due to epigenetic changes at the imprinted GNAS locus, including loss of methylation at the A/B differentially methylated region (DMR) and sometimes at the XL and AS DMRs and gain of methylation at the NESP DMR. OBJECTIVE To investigate if quantitative measurement of the methylation at the GNAS DMRs identifies subtypes of PHP-Ib. DESIGN AND METHODS In 19 patients with PHP-Ib and 7 controls, methylation was characterised at the four GNAS DMRs through combined bisulfite restriction analysis and quantified through cytosine specific real-time PCR in blood lymphocyte DNA. RESULTS A principal component analysis using the per cent of methylation at seven cytosines of the GNAS locus provided three clusters of subjects (controls n=7, autosomal dominant PHP-Ib with loss of methylation restricted to the A/B DMR n=3, and sporadic PHP-Ib with broad GNAS methylation changes n=16) that matched perfectly the combined bisulfite restriction analysis classification. Furthermore, three sub-clusters of patients with sporadic PHP-Ib, that displayed different patterns of methylation, were identified: incomplete changes at all DMRs compatible with somatic mosaicism (n=5), profound epigenetic changes at all DMRs (n=8), and unmodified methylation at XL in contrast with the other DMRs (n=3). Interestingly, parathyroid hormone concentration at the time of diagnosis correlated with the per cent of methylation at the A/B DMR. CONCLUSION Quantitative assessment of the methylation in blood lymphocyte DNA is of clinical relevance, allows the diagnosis of PHP-Ib, and identifies subtypes of PHP-Ib. These epigenetic findings suggest mosaicism at least in some patients.
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Collinson M, Leonard SJ, Charlton J, Crolla JA, Silve C, Hall CM, Oglivie C, James MA, Smithson SF. Symmetrical enchondromatosis is associated with duplication of 12p11.23 to 12p11.22 including PTHLH. Am J Med Genet A 2010; 152A:3124-8. [DOI: 10.1002/ajmg.a.33567] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Couvineau A, Wouters V, Bertrand G, Rouyer C, Gérard B, Boon LM, Grandchamp B, Vikkula M, Silve C. PTHR1 mutations associated with Ollier disease result in receptor loss of function. Hum Mol Genet 2008; 17:2766-75. [PMID: 18559376 PMCID: PMC2722890 DOI: 10.1093/hmg/ddn176] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PTHR1-signaling pathway is critical for the regulation of endochondral ossification. Thus, abnormalities in genes belonging to this pathway could potentially participate in the pathogenesis of Ollier disease/Maffucci syndrome, two developmental disorders defined by the presence of multiple enchondromas. In agreement, a functionally deleterious mutation in PTHR1 (p.R150C) was identified in enchondromas from two of six unrelated patients with enchondromatosis. However, neither the p.R150C mutation (26 tumors) nor any other mutation in the PTHR1 gene (11 patients) could be identified in another study. To further define the role of PTHR1-signaling pathway in Ollier disease and Maffucci syndrome, we analyzed the coding sequences of four genes (PTHR1, IHH, PTHrP and GNAS1) in leucocyte and/or tumor DNA from 61 and 23 patients affected with Ollier disease or Maffucci syndrome, respectively. We identified three previously undescribed missense mutations in PTHR1 in patients with Ollier disease at the heterozygous state. Two mutations (p.G121E, p.A122T) were present only in enchondromas, and one (p.R255H) in both enchondroma and leukocyte DNA. Assessment of receptor function demonstrated that these three mutations impair PTHR1 function by reducing either the affinity of the receptor for PTH or the receptor expression at the cell surface. These mutations were not found in DNA from 222 controls. Including our data, PTHR1 functionally deleterious mutations have now been identified in five out 31 enchondromas from Ollier patients. These findings provide further support for the idea that heterozygous mutations in PTHR1 that impair receptor function participate in the pathogenesis of Ollier disease in some patients.
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Karim Z, Gérard B, Bakouh N, Alili R, Leroy C, Beck L, Silve C, Planelles G, Urena-Torres P, Grandchamp B, Friedlander G, Prié D. NHERF1 mutations and responsiveness of renal parathyroid hormone. N Engl J Med 2008; 359:1128-35. [PMID: 18784102 DOI: 10.1056/nejmoa0802836] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Impaired renal phosphate reabsorption, as measured by dividing the tubular maximal reabsorption of phosphate by the glomerular filtration rate (TmP/GFR), increases the risks of nephrolithiasis and bone demineralization. Data from animal models suggest that sodium-hydrogen exchanger regulatory factor 1 (NHERF1) controls renal phosphate transport. We sequenced the NHERF1 gene in 158 patients, 94 of whom had either nephrolithiasis or bone demineralization. We identified three distinct mutations in seven patients with a low TmP/GFR value. No patients with normal TmP/GFR values had mutations. The mutants expressed in cultured renal cells increased the generation of cyclic AMP (cAMP) by parathyroid hormone (PTH) and inhibited phosphate transport. These NHERF1 mutations suggest a previously unrecognized cause of renal phosphate loss in humans.
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Mannstadt M, Bertrand G, Muresan M, Weryha G, Leheup B, Pulusani SR, Grandchamp B, Jüppner H, Silve C. Dominant-negative GCMB mutations cause an autosomal dominant form of hypoparathyroidism. J Clin Endocrinol Metab 2008; 93:3568-76. [PMID: 18583467 PMCID: PMC2567849 DOI: 10.1210/jc.2007-2167] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Hypoparathyroidism (HP) is characterized by low PTH levels, hypocalcemia, and hyperphosphatemia. Heterozygous mutations in pre-pro-PTH or the calcium-sensing receptor (CaSR) cause some forms of autosomal dominant HP (AD-HP). Furthermore, homozygous mutations in glial cells missing B (GCMB) have been implicated in autosomal recessive HP (AR-HP). In most other HP patients, however, the molecular defect remains undefined. OBJECTIVE Our objectives were to determine the genetic defect in the affected members of two unrelated families with AD-HP and define the underlying disease mechanism. SUBJECTS Several family members affected by AD-HP were investigated. The proband in family A had low calcium detected on routine blood testing, whereas the proband in family B had symptomatic hypocalcemia. METHODS Mutational analysis of the genes encoding pre-pro-PTH, CaSR, and GCMB was performed using PCR-amplified genomic DNA of the probands and other available members of each family. The identified GCMB mutants were characterized by Western blot analysis and luciferase reporter assay using DF-1 fibroblasts. RESULTS Two novel heterozygous mutations located in the last GCMB exon (c.1389delT and c.1399delC in families A and B, respectively) were identified that both lead to frame-shifts and replacement of the putative second transactivation domain within carboxyl-terminal region by unrelated amino acid sequence. The mutant GCMB proteins were well expressed, and both showed dose-dependent inhibition of the transactivation capacity of wild-type protein in luciferase reporter assays. CONCLUSIONS The dominant-negative effect observed in vitro for both GCMB mutations provides a plausible explanation for the impaired PTH secretion observed in the two unrelated families with AD-HP.
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Torres PU, Prié D, Molina-Blétry V, Beck L, Silve C, Friedlander G. Klotho: an antiaging protein involved in mineral and vitamin D metabolism. Kidney Int 2007; 71:730-7. [PMID: 17332731 DOI: 10.1038/sj.ki.5002163] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Klotho gene mutation leads to a syndrome strangely resembling chronic kidney disease patients undergoing dialysis with multiple accelerated age-related disorders, including hypoactivity, sterility, skin thinning, muscle atrophy, osteoporosis, vascular calcifications, soft-tissue calcifications, defective hearing, thymus atrophy, pulmonary emphysema, ataxia, and abnormalities of the pituitary gland, as well as hypoglycemia, hyperphosphatemia, and paradoxically high-plasma calcitriol levels. Conversely, mice overexpressing klotho show an extended existence and a slow aging process through a mechanism that may involve the induction of a state of insulin and oxidant stress resistance. Two molecules are produced by the klotho gene, a membrane bound form and a circulating form. However, their precise biological roles and molecular functions have been only partly deciphered. Klotho can act as a circulating factor or hormone, which binds to a not yet identified high-affinity receptor and inhibits the intracellular insulin/insulin-like growth factor-1 (IGF-1) signaling cascade; klotho can function as a novel beta-glucuronidase, which deglycosylates steroid beta-glucuronides and the calcium channel transient receptor potential vallinoid-5 (TRPV5); as a cofactor essential for the stimulation of fibroblast growth factor (FGF) receptor by FGF23. The two last functions have propelled klotho to the group of key factors regulating mineral and vitamin D metabolism, and have also stimulated the interest of the nephrology community. The purpose of this review is to provide a nephrology-oriented overview of klotho and its potential implications in normal and altered renal function states.
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Abstract
Enchondromas are common intraosseous, usually benign cartilaginous tumors, that develop in close proximity to growth plate cartilage. When multiple enchondromas are present, the condition is called enchondromatosis also known as Ollier disease (WHO terminology). The estimated prevalence of Ollier disease is 1/100,000. Clinical manifestations often appear in the first decade of life. Ollier disease is characterized by an asymmetric distribution of cartilage lesions and these can be extremely variable (in terms of size, number, location, evolution of enchondromas, age of onset and of diagnosis, requirement for surgery). Clinical problems caused by enchondromas include skeletal deformities, limb-length discrepancy, and the potential risk for malignant change to chondrosarcoma. The condition in which multiple enchondromatosis is associated with soft tissue hemangiomas is known as Maffucci syndrome. Until now both Ollier disease and Maffucci syndrome have only occurred in isolated patients and not familial. It remains uncertain whether the disorder is caused by a single gene defect or by combinations of (germ-line and/or somatic) mutations. The diagnosis is based on clinical and conventional radiological evaluations. Histological analysis has a limited role and is mainly used if malignancy is suspected. There is no medical treatment for enchondromatosis. Surgery is indicated in case of complications (pathological fractures, growth defect, malignant transformation). The prognosis for Ollier disease is difficult to assess. As is generally the case, forms with an early onset appear more severe. Enchondromas in Ollier disease present a risk of malignant transformation of enchondromas into chondrosarcomas.
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Benoist-Lasselin C, de Margerie E, Gibbs L, Cormier S, Silve C, Nicolas G, LeMerrer M, Mallet JF, Munnich A, Bonaventure J, Zylberberg L, Legeai-Mallet L. Defective chondrocyte proliferation and differentiation in osteochondromas of MHE patients. Bone 2006; 39:17-26. [PMID: 16476576 DOI: 10.1016/j.bone.2005.12.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 11/28/2005] [Accepted: 12/13/2005] [Indexed: 11/26/2022]
Abstract
Multiple hereditary exostoses (MHE) is an autosomal dominant skeletal disorder caused by mutations in one of the two EXT genes and characterized by multiple osteochondromas that generally arise near the ends of growing long bones. Defective endochondral ossification is likely to be involved in the formation of osteochondromas. In order to investigate potential changes in chondrocyte proliferation and/or differentiation during this process, osteochondroma samples from MHE patients were obtained and used for genetic, morphological, immunohistological, and in situ hybridization studies. The expression patterns of IHH (Indian hedgehog) and FGFR3 (Fibroblast Growth Factor Receptor 3) were similar with transcripts expressed throughout osteochondromas. Expression of PTHR1 (Parathyroid Hormone Receptor 1) transcripts was restricted to a narrow zone of prehypertrophic chondrocytes. Numerous cells forming osteochondromas although resembling prehypertrophic chondrocytes, stained positively with an anti-proliferating cell nuclear antigen (PCNA) antibody. In addition, ectopic expression of collagen type I and abnormal presence of osteocalcin (OC), osteopontin (OP), and bone sialoprotein (BSP) were observed in the cartilaginous osteochondromas. These data indicate that most chondrocytes involved in the growth of osteochondromas can proliferate, and that some of them exhibit bone-forming cell characteristics. We conclude that in MHE, defective heparan sulfate biosynthesis caused by EXT mutations maintains the proliferative capacity of chondrocytes and promotes phenotypic modification to bone-forming cells.
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Prié D, Beck L, Silve C, Friedlander G. Hypophosphatemia and calcium nephrolithiasis. Nephron Clin Pract 2006; 98:e50-4. [PMID: 15499207 DOI: 10.1159/000080256] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Our knowledge of phosphate balance under physiological and pathological situations has increased substantially during the last decade thanks to the molecular identification of three dissimilar families of sodium-phosphate cotransport systems, two of them almost exclusively expressed in epithelia whereas the third one has a ubiquitous expression. Intracellular proteins such as NHERF1 (sodium-proton exchanger regulatory factor 1) can interact with phosphate transporters through PDZ domains thus regulating the expression of the transporters at the membrane. Moreover, newly acknowledged paracrine/endocrine peptides, such as fibroblast growth factor 23 (FGF23), also affect the activity of phosphate transporters. Renal phosphate leak, related to invalidation (in the mouse) or to mutations (in humans) of the renal phosphate transporter NPT2a, leads to hypophosphatemia on the one hand, and to nephrolithiasis or bone demineralization on the other hand. Similar features are observed during invalidation of NHERF or in case of overproduction of FGF23. These observations highlight the importance of phosphate homeostasis in common diseases such as renal stones or bone loss.
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Bonaventure J, Silve C. Dysplasies osseuses héréditaires et voies de signalisation associées aux récepteurs FGFR3 et PTHR1. Med Sci (Paris) 2005; 21:954-61. [PMID: 16274647 DOI: 10.1051/medsci/20052111954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Skeletal development is a highly sophisticated process involving, as a first step, migration and condensation of mesenchymal cells into osteoprogenitor cells. These cells further differentiate into chondrocytes and osteoblasts through multiple differentiation stages requiring a set of specific transcriptional factors. Defective endochondral ossification in human is associated with a large number of inherited skeletal dysplasias caused by mutations in genes encoding extracellular matrix components, growth factors and their receptors, signaling molecules and transcription factors. This review summarizes some of the recent findings on a series of chondrodysplasias caused by mutations in FGFR3 and PTHR1, two receptors expressed in the cartilage growth plate and mediating two main signaling pathways. Data from human diseases and relevant animal models provide new clues for understanding how signaling molecules and their interaction with key transcription factors control and regulate the development and growth of long bones.
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MESH Headings
- Animals
- Cell Differentiation/genetics
- Cell Differentiation/physiology
- Chondrogenesis/genetics
- Chondrogenesis/physiology
- Fibroblast Growth Factor 3/physiology
- Growth Plate/pathology
- Humans
- Mesoderm/cytology
- Models, Animal
- Models, Genetic
- Mutation
- Osteochondrodysplasias/genetics
- Osteochondrodysplasias/physiopathology
- Osteogenesis/genetics
- Osteogenesis/physiology
- Parathyroid Hormone/physiology
- Receptor, Fibroblast Growth Factor, Type 3/deficiency
- Receptor, Fibroblast Growth Factor, Type 3/genetics
- Receptor, Fibroblast Growth Factor, Type 3/physiology
- Receptor, Parathyroid Hormone, Type 1
- Receptors, Parathyroid Hormone/deficiency
- Receptors, Parathyroid Hormone/genetics
- Receptors, Parathyroid Hormone/physiology
- Signal Transduction/genetics
- Signal Transduction/physiology
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Abstract
Until recently, the action of two hormones - parathyroid hormone (PTH) and calcitriol - on three target tissues - bone, kidney, and gut - has been thought to regulate the closely linked homeostasis of calcium and phosphates. In this system, an increase in the plasma concentration of one ion often leads to a reciprocal change in the concentration of the other and PTH stimulates 1 alpha-hydroxylase activity and calcitriol synthesis in renal proximal tubular cells. A second phosphate regulation system was recently identified. It involves one or more phosphaturic hormones, called "phosphatonins", that is, circulating factors with potent phosphaturic activity. The key phosphatonin appears to be a fibroblast growth factor, known as FGF23. It is now established that FGF23 regulates not only phosphate homeostasis, but also vitamin D metabolism. In contrast to PTH, however, FGF23 inhibits rather than stimulates 1 alpha-hydroxylase activity and calcitriol synthesis.
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Silve C, Petrel C, Leroy C, Bruel H, Mallet E, Rognan D, Ruat M. Delineating a Ca2+ Binding Pocket within the Venus Flytrap Module of the Human Calcium-sensing Receptor. J Biol Chem 2005; 280:37917-23. [PMID: 16147994 DOI: 10.1074/jbc.m506263200] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Ca(2+)-sensing receptor (CaSR) belongs to the class III G-protein-coupled receptors (GPCRs), which include receptors for pheromones, amino acids, sweeteners, and the neurotransmitters glutamate and gamma-aminobutyric acid (GABA). These receptors are characterized by a long extracellular amino-terminal domain called a Venus flytrap module (VFTM) containing the ligand binding pocket. To elucidate the molecular determinants implicated in Ca(2+) recognition by the CaSR VFTM, we developed a homology model of the human CaSR VFTM from the x-ray structure of the metabotropic glutamate receptor type 1 (mGluR1), and a phylogenetic analysis of 14 class III GPCR VFTMs. We identified critical amino acids delineating a Ca(2+) binding pocket predicted to be adjacent to, but distinct from, a cavity reminiscent of the binding site described for amino acids in mGluRs, GABA-B receptor, and GPRC6a. Most interestingly, these Ca(2+)-contacting residues are well conserved within class III GPCR VFTMs. Our model was validated by mutational and functional analysis, including the characterization of activating and inactivating mutations affecting a single amino acid, Glu-297, located within the proposed Ca(2+) binding pocket of the CaSR and associated with autosomal dominant hypocalcemia and familial hypocalciuric hypercalcemia, respectively, genetic diseases characterized by perturbations in Ca(2+) homeostasis. Altogether, these data define a Ca(2+) binding pocket within the CaSR VFTM that may be conserved in several other class III GPCRs, thereby providing a molecular basis for extracellular Ca(2+) sensing by these receptors.
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