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Ohata Y, Kakimoto H, Seki Y, Ishihara Y, Nakano Y, Yamamoto K, Takeyari S, Fujiwara M, Kitaoka T, Takakuwa S, Kubota T, Ozono K. Pathogenic variants of the GNAS gene introduce an abnormal amino acid sequence in the β6 strand/α5 helix of Gsα, causing pseudohypoparathyroidism type 1A and pseudopseudohypoparathyroidism in two unrelated Japanese families. Bone Rep 2022; 17:101637. [PMID: 36407415 PMCID: PMC9668531 DOI: 10.1016/j.bonr.2022.101637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/03/2022] [Accepted: 11/09/2022] [Indexed: 11/11/2022] Open
Abstract
Pseudohypoparathyroidism 1A (PHP1A) and pseudopseudohypoparathyroidism (PPHP) are caused by loss-of-function variants of GNAS, which encodes Gsα. We present two unrelated Japanese families with PHP1A and PPHP harboring unreported pathogenic variants of GNAS (c.1141delG, p.Asp381Thrfs*23 and c.1117delC, p.Arg373Alafs*31). These variants introduce abnormal amino acids in the β6 strand/α5 helix of Gsα, which interact with G protein coupling receptor (GPCR). We conclude that these variants alter the association of Gsα with GPCR and cause PHP1A or PPHP. Reports of GNAS variants causing extra amino acid sequences are limited. Two cases with extended Gsα mutants showed clinical characteristics of PHP1A/PPHP. No change was found in the affinity between mutant Gsα and GDP using I-TASSER. I-TASSER and AlphaFold2 suggested the Gsα mutants caused dysfunction with GPCR. Prediction by I-TASSER and AlphaFold2 are useful in determination of pathogenicity.
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Affiliation(s)
- Yasuhisa Ohata
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Haruna Kakimoto
- Department of Pediatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yuko Seki
- Department of Pediatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yasuki Ishihara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
- The first Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Japan
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yukako Nakano
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kenichi Yamamoto
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
- Department of Statistical Genetics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Shinji Takeyari
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Makoto Fujiwara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
- The first Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Taichi Kitaoka
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Satoshi Takakuwa
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
- Department of Pediatrics, Hyogo Prefectural Nishinomiya Hospital, Japan
| | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
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Nonaka S, Hashimoto T, Oda I, Sekine S. Sporadic pyloric gland adenoma associated with a large fundic gland polyp: genetic evidence for stepwise progression. Gastric Cancer 2020; 23:1102-1106. [PMID: 32415517 DOI: 10.1007/s10120-020-01082-4] [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: 03/25/2020] [Accepted: 05/03/2020] [Indexed: 02/07/2023]
Abstract
Pyloric gland adenoma (PGA) is an uncommon variant of gastric adenoma exhibiting pyloric gland/mucous neck cell differentiation. We present a sporadic PGA associated with a large fundic gland polyp (FGP) in a woman in her 40 s without Helicobacter pylori infection. The polyp, measuring 25 mm in size, was located in the middle gastric body and was removed by endoscopic submucosal dissection. Histological examination revealed three morphologically distinct components: FGP, FGP with large cysts, and PGA. A genetic analysis identified a truncating APC mutation in all the three components, supporting their histogenetic relationship. Additionally, a GNAS mutation was detected in two components, FGP with large cysts and PGA, whereas a KRAS mutation was exclusively found in the PGA component. Thus, despite the unusual presentation, the PGA component harbored prototypical genetic alterations. The differential genetic alterations observed in the three components imply that they represent stepwise progression from FGP to PGA.
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Affiliation(s)
- Satoru Nonaka
- Endoscopy Division, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan
| | - Taiki Hashimoto
- Division of Diagnostic Pathology, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan
| | - Ichiro Oda
- Endoscopy Division, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan
| | - Shigeki Sekine
- Division of Diagnostic Pathology, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan. .,Division of Molecular Pathology, National Cancer Center Research Institute, 5-1-1, Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan.
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Makita N, Ando T, Sato J, Manaka K, Mitani K, Kikuchi Y, Niwa T, Ootaki M, Takeba Y, Matsumoto N, Kawakami A, Ogawa T, Nangaku M, Iiri T. Cinacalcet corrects biased allosteric modulation of CaSR by AHH autoantibody. JCI Insight 2019; 4:126449. [PMID: 30996138 DOI: 10.1172/jci.insight.126449] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/12/2019] [Indexed: 12/13/2022] Open
Abstract
Biased agonism is a paradigm that may explain the selective activation of a signaling pathway via a GPCR that activates multiple signals. The autoantibody-induced inactivation of the calcium-sensing receptor (CaSR) causes acquired hypocalciuric hypercalcemia (AHH). Here, we describe an instructive case of AHH in which severe hypercalcemia was accompanied by an increased CaSR antibody titer. These autoantibodies operated as biased allosteric modulators of CaSR by targeting its Venus flytrap domain near the Ca2+-binding site. A positive allosteric modulator of CaSR, cinacalcet, which targets its transmembrane domain, overcame this autoantibody effect and successfully corrected the hypercalcemia in this patient. Hence, this is the first study to our knowledge that identifies the interaction site of a disease-causing GPCR autoantibody working as its biased allosteric modulator and demonstrates that cinacalcet can correct the AHH autoantibody effects both in vitro and in our AHH patient. Our observations provide potentially new insights into how biased agonism works and how to design a biased allosteric modulator of a GPCR. Our observations also indicate that the diagnosis of AHH is important because the severity of hypercalcemia may become fatal if the autoantibody titer increases. Calcimimetics may serve as good treatment options for some patients with severe AHH.
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Affiliation(s)
- Noriko Makita
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Takao Ando
- Division of Endocrinology and Metabolism, Nagasaki Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Junichiro Sato
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Katsunori Manaka
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Koji Mitani
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Yasuko Kikuchi
- Department of Breast and Endocrine Surgery, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Takayoshi Niwa
- Department of Breast and Endocrine Surgery, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Masanori Ootaki
- Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Yuko Takeba
- Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Naoki Matsumoto
- Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Atsushi Kawakami
- Division of Endocrinology and Metabolism, Nagasaki Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Toshihisa Ogawa
- Breast Center, Dokkyo Medical University Koshigaya Hospital, Saitama, Japan
| | - Masaomi Nangaku
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan
| | - Taroh Iiri
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan.,Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan
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Makita N, Sato T, Yajima-Shoji Y, Sato J, Manaka K, Eda-Hashimoto M, Ootaki M, Matsumoto N, Nangaku M, Iiri T. Analysis of the V2 Vasopressin Receptor (V2R) Mutations Causing Partial Nephrogenic Diabetes Insipidus Highlights a Sustainable Signaling by a Non-peptide V2R Agonist. J Biol Chem 2016; 291:22460-22471. [PMID: 27601473 DOI: 10.1074/jbc.m116.733220] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 09/05/2016] [Indexed: 11/06/2022] Open
Abstract
Disease-causing mutations in G protein-coupled receptor (GPCR) genes, including the V2 vasopressin receptor (V2R) gene, often cause misfolded receptors, leading to a defect in plasma membrane trafficking. A novel V2R mutation, T273M, identified in a boy with partial nephrogenic diabetes insipidus (NDI), shows intracellular localization and partial defects similar to the two mutants we described previously (10). Although non-peptide V2R antagonists have been shown to rescue the membrane localization of V2R mutants, their level of functional rescue is weak. Interestingly, it has been reported that a non-peptide agonist, OPC51803, activates misfolded V2R mutants intracellularly without degradation, thus potentially serving as a therapeutic agent against NDI (14). In our current experiments, however, a peptide antagonist blocked arginine vasopressin (AVP)- or OPC51803-stimulated cAMP accumulation both in COS-7 and MDCK cells, suggesting that OPC51803 mainly stimulates cell surface V2R mutants. In addition, our analyses revealed that OPC51803 works not only as a non-peptide agonist that causes activation/β-arrestin-dependent desensitization of V2R mutants expressed at the plasma membrane but also as a pharmacochaperone that promotes the endoplasmic reticulum-retained mutant maturation and trafficking to the plasma membrane. The ratio of the pharmacochaperone effect to the desensitization effect likely correlates negatively with the residual function of the tested mutants, suggesting that OPC5 has a more favorable effect on the V2R mutants with a less residual function. We speculated that the canceling of the desensitization effect of OPC51803 by the pharmacochaperone effect after long-term treatment may produce sustainable signaling, and thus pharmacochaperone agonists such as OPC51803 may serve as promising therapeutics for NDI caused by misfolded V2R mutants.
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Affiliation(s)
- Noriko Makita
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan,
| | - Tomohiko Sato
- the Department of Pediatrics, Hirosaki University Graduate School of Medicine, Hirosaki, 036-8562 Japan, and
| | - Yuki Yajima-Shoji
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan
| | - Junichiro Sato
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan
| | - Katsunori Manaka
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan
| | - Makiko Eda-Hashimoto
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan
| | - Masanori Ootaki
- the Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki 216-8511, Japan
| | - Naoki Matsumoto
- the Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki 216-8511, Japan
| | - Masaomi Nangaku
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan
| | - Taroh Iiri
- From the Department of Endocrinology and Nephrology, University of Tokyo, Tokyo 113-8655, Japan, .,the Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki 216-8511, Japan
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A Novel T55A Variant of Gs α Associated with Impaired cAMP Production, Bone Fragility, and Osteolysis. Case Rep Endocrinol 2016; 2016:2691385. [PMID: 27579188 PMCID: PMC4992514 DOI: 10.1155/2016/2691385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 06/03/2016] [Accepted: 07/03/2016] [Indexed: 01/08/2023] Open
Abstract
G-protein coupled receptors (GPCRs) mediate a wide spectrum of biological activities. The GNAS complex locus encodes the stimulatory alpha subunit of the guanine nucleotide binding protein (Gsα) and regulates production of the second messenger cyclic AMP (cAMP). Loss-of-function GNAS mutations classically lead to Albright's Hereditary Osteodystrophy (AHO) and pseudohypoparathyroidism, often with significant effects on bone formation and mineral metabolism. We present the case of a child who exhibits clinical features of osteolysis, multiple childhood fractures, and neonatal SIADH. Exome sequencing revealed a novel de novo heterozygous missense mutation of GNAS (c.163A<G, p.T55A) affecting the p-loop of the catalytic Gsα GTPase domain. In order to further assess whether this unique mutation resulted in a gain or loss of function of Gsα, we introduced the mutation into a rat GNAS plasmid and performed functional studies to assess the level of cAMP activity associated with this mutation. We identified a 64% decrease in isoproterenol-induced cAMP production in vitro, compared to wild type, consistent with loss of Gsα activity. Despite a significant decrease in isoproterenol-induced cAMP production in vitro, this mutation did not produce a classical AHO phenotype in our patient; however, it may account for her presentation with childhood fractures and osteolysis.
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Abstract
The GNAS complex locus encodes the alpha-subunit of the stimulatory G protein (Gsα), a ubiquitous signaling protein mediating the actions of many hormones, neurotransmitters, and paracrine/autocrine factors via generation of the second messenger cAMP. GNAS gives rise to other gene products, most of which exhibit exclusively monoallelic expression. In contrast, Gsα is expressed biallelically in most tissues; however, paternal Gsα expression is silenced in a small number of tissues through as-yet-poorly understood mechanisms that involve differential methylation within GNAS. Gsα-coding GNAS mutations that lead to diminished Gsα expression and/or function result in Albright's hereditary osteodystrophy (AHO) with or without hormone resistance, i.e., pseudohypoparathyroidism type-Ia/Ic and pseudo-pseudohypoparathyroidism, respectively. Microdeletions that alter GNAS methylation and, thereby, diminish Gsα expression in tissues in which the paternal Gsα allele is normally silenced also cause hormone resistance, which occurs typically in the absence of AHO, a disorder termed pseudohypoparathyroidism type-Ib. Mutations of GNAS that cause constitutive Gsα signaling are found in patients with McCune-Albright syndrome, fibrous dysplasia of bone, and different endocrine and non-endocrine tumors. Clinical features of these diseases depend significantly on the parental allelic origin of the GNAS mutation, reflecting the tissue-specific paternal Gsα silencing. In this article, we review the pathogenesis and the phenotypes of these human diseases.
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Affiliation(s)
- Serap Turan
- Pediatric Endocrinology, Marmara University School of Medicine Hospital, Istanbul, Turkey;
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114;
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Turan S, Bastepe M. The GNAS complex locus and human diseases associated with loss-of-function mutations or epimutations within this imprinted gene. Horm Res Paediatr 2013; 80:229-41. [PMID: 24107509 PMCID: PMC3874326 DOI: 10.1159/000355384] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 08/29/2013] [Indexed: 12/14/2022] Open
Abstract
GNAS is a complex imprinted locus leading to several different gene products that show exclusive monoallelic expression. GNAS also encodes the α-subunit of the stimulatory G protein (Gsα), a ubiquitously expressed signaling protein that is essential for the actions of many hormones and other endogenous molecules. Gsα is expressed biallelically in most tissues but its expression is silenced from the paternal allele in a small number of tissues. The tissue-specific paternal silencing of Gsα results in different parent-of-origin-specific phenotypes in patients who carry inactivating GNAS mutations. In this paper, we review the GNAS complex locus and discuss how disruption of Gsα expression and the expression of other GNAS products shape the phenotypes of human disorders caused by mutations in this gene.
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Affiliation(s)
- Serap Turan
- Pediatric Endocrinology, Marmara University School of Medicine Hospital, Istanbul, Turkey
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA
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8
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Makita N, Kabasawa Y, Otani Y, Firman, Sato J, Hashimoto M, Nakaya M, Nishihara H, Nangaku M, Kurose H, Ohwada T, Iiri T. Attenuated desensitization of β-adrenergic receptor by water-soluble N-nitrosamines that induce S-nitrosylation without NO release. Circ Res 2012; 112:327-34. [PMID: 23212582 DOI: 10.1161/circresaha.112.277665] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RATIONALE The clinical problem of loss of β-adrenergic receptor (β-AR) response, both in the pathogenesis of heart failure and during therapeutic application of β-agonists, is attributable, at least in part, to desensitization, internalization, and downregulation of the receptors. In the regulation of β-AR signaling, G protein-coupled receptor kinase 2 (GRK2) primarily phosphorylates agonist-occupied β-ARs, and this modification promotes desensitization, internalization, and downregulation of β-ARs. It has been demonstrated that GRK2 is inhibited by its S-nitrosylation. However, compounds that induce S-nitrosylation, such as S-nitrosoglutathione, simultaneously generate NO, which has been demonstrated to operate for cardiovascular protection. OBJECTIVE We examine whether S-nitrosylation without NO generation inhibits desensitization of β(2)-AR by GRK2. We thus aim to synthesize compounds that specifically induce S-nitrosylation. METHODS AND RESULTS We have developed water-soluble N-nitrosamines that have S-nitrosylating activity but lack NO-generating activity. These compounds, at least partly, rescue β-AR from desensitization in HEK 293 cells expressing FLAG-tagged human β(2)-AR and in rat cardiac myocytes. They inhibit isoproterenol-dependent phosphorylation and internalization of β(2)-AR. Indeed, they nitrosylate GRK2 in vitro and in cells, and their S-nitrosylation of GRK2 likely underlies their inhibition of β(2)-AR desensitization. CONCLUSIONS Compounds that induce S-nitrosylation without NO release inhibit GRK2 and attenuate β(2)-AR desensitization. Developing water-soluble drugs that specifically induce S-nitrosylation may be a promising therapeutic strategy for heart failure.
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Affiliation(s)
- Noriko Makita
- Department of Endocrinology and Nephrology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Oishi A, Makita N, Sato J, Iiri T. Regulation of RhoA signaling by the cAMP-dependent phosphorylation of RhoGDIα. J Biol Chem 2012; 287:38705-15. [PMID: 23012358 DOI: 10.1074/jbc.m112.401547] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RhoA plays a pivotal role in regulating cell shape and movement. Protein kinase A (PKA) inhibits RhoA signaling and thereby induces a characteristic morphological change, cell rounding. This has been considered to result from cAMP-induced phosphorylation of RhoA at Ser-188, which induces a stable RhoA-GTP-RhoGDIα complex and sequesters RhoA to the cytosol. However, few groups have shown RhoA phosphorylation in intact cells. Here we show that phosphorylation of RhoGDIα but not RhoA plays an essential role in the PKA-induced inhibition of RhoA signaling and in the morphological changes using cardiac fibroblasts. The knockdown of RhoGDIα by siRNA blocks cAMP-induced cell rounding, which is recovered by RhoGDIα-WT expression but not when a RhoGDIα-S174A mutant is expressed. PKA phosphorylates RhoGDIα at Ser-174 and the phosphorylation of RhoGDIα is likely to induce the formation of a active RhoA-RhoGDIα complex. Our present results thus reveal a principal molecular mechanism underlying G(s)/cAMP-induced cross-talk with G(q)/G(13)/RhoA signaling.
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Affiliation(s)
- Atsuro Oishi
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo 113-8655, Japan
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Takahashi K, Makita N, Manaka K, Hisano M, Akioka Y, Miura K, Takubo N, Iida A, Ueda N, Hashimoto M, Fujita T, Igarashi T, Sekine T, Iiri T. V2 vasopressin receptor (V2R) mutations in partial nephrogenic diabetes insipidus highlight protean agonism of V2R antagonists. J Biol Chem 2011; 287:2099-106. [PMID: 22144672 DOI: 10.1074/jbc.m111.268797] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inactivating mutations of the V2 vasopressin receptor (V2R) cause cross-linked congenital nephrogenic diabetes insipidus (NDI), resulting in renal resistance to the antidiuretic hormone AVP. In two families showing partial NDI, characterized by an apparently normal response to diagnostic tests and an increase in the basal ADH levels suggesting AVP resistance, we have identified two V2R mutations, Ser-333del and Y128S. Both mutant V2Rs, when expressed in COS-7 cells, show partial defects in vasopressin-stimulated cAMP accumulation and intracellular localization. The inhibition of internalization does not rescue their localization. In contrast, the non-peptide V2R antagonists OPC41061 and OPC31260 partially rescue the membrane localization and basal function of these V2R mutants, whereas they inhibit the basal activity of the wild-type V2R. These results indicate that a partial loss of function of Ser-333del and Y128S mutant V2Rs results from defective membrane trafficking. These findings further indicate that V2R antagonists can act as protean agonists, serving as pharmacological chaperones for inactivating V2R mutants and also as inverse agonists of wild-type receptors. We speculate that this protean agonism could underlie the possible dual beneficial effects of the V2R antagonist: improvement of hyponatremia with heart failure or polycystic kidney disease and potential rescue of NDI.
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Affiliation(s)
- Kazuhiro Takahashi
- Department of Pediatrics, The University of Tokyo, Tokyo 113-8655, Japan
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Protein palmitoylation and subcellular trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2981-94. [DOI: 10.1016/j.bbamem.2011.07.009] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/06/2011] [Accepted: 07/12/2011] [Indexed: 02/07/2023]
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12
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Liu Z, Turan S, Wehbi VL, Vilardaga JP, Bastepe M. Extra-long Gαs variant XLαs protein escapes activation-induced subcellular redistribution and is able to provide sustained signaling. J Biol Chem 2011; 286:38558-38569. [PMID: 21890629 DOI: 10.1074/jbc.m111.240150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Murine models indicate that Gαs and its extra-long variant XLαs, both of which are derived from GNAS, markedly differ regarding their cellular actions, but these differences are unknown. Here we investigated activation-induced trafficking of Gαs and XLαs, using immunofluorescence microscopy, cell fractionation, and total internal reflection fluorescence microscopy. In transfected cells, XLαs remained localized to the plasma membrane, whereas Gαs redistributed to the cytosol after activation by GTPase-inhibiting mutations, cholera toxin treatment, or G protein-coupled receptor agonists (isoproterenol or parathyroid hormone (PTH)(1-34)). Cholera toxin treatment or agonist (isoproterenol or pituitary adenylate cyclase activating peptide-27) stimulation of PC12 cells expressing Gαs and XLαs endogenously led to an increased abundance of Gαs, but not XLαs, in the soluble fraction. Mutational analyses revealed two conserved cysteines and the highly charged domain as being critically involved in the plasma membrane anchoring of XLαs. The cAMP response induced by M-PTH(1-14), a parathyroid hormone analog, terminated quickly in HEK293 cells stably expressing the type 1 PTH/PTH-related peptide receptor, whereas the response remained maximal for at least 6 min in cells that co-expressed the PTH receptor and XLαs. Although isoproterenol-induced cAMP response was not prolonged by XLαs expression, a GTPase-deficient XLαs mutant found in certain tumors and patients with fibrous dysplasia of bone and McCune-Albright syndrome generated more basal cAMP accumulation in HEK293 cells and caused more severe impairment of osteoblastic differentiation of MC3T3-E1 cells than the cognate Gαs mutant (gsp oncogene). Thus, activated XLαs and Gαs traffic differently, and this may form the basis for the differences in their cellular actions.
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Affiliation(s)
- Zun Liu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Serap Turan
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Pediatric Endocrinology, Marmara University School of Medicine Hospital, 34662 Istanbul, Turkey
| | - Vanessa L Wehbi
- Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Jean-Pierre Vilardaga
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
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Garcia-Marcos M, Ghosh P, Farquhar MG. Molecular basis of a novel oncogenic mutation in GNAO1. Oncogene 2011; 30:2691-6. [PMID: 21317923 DOI: 10.1038/onc.2010.645] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Heterotrimeric G proteins are molecular switches that control signal transduction, and their dysregulation can promote oncogenesis. Somatic mutations in GNAS, GNAI2 and GNAQ genes induce oncogenesis by rendering Gα subunits constitutively activated. Recently the first somatic mutation, arginine(243) → histidine (R243H) in the GNAO1 (Gαo) gene was identified in breast carcinomas and shown to promote oncogenic transformation when introduced into cells. Here, we provide the molecular basis for the oncogenic properties of the Gαo R243H mutant. Using limited proteolysis assays, nucleotide-binding assays, and single-turnover and steady-state GTPase assays, we demonstrate that the oncogenic R234H mutation renders Gαo constitutively active by accelerating the rate of nucleotide exchange; however, this mutation does not affect Gαo's ability to become deactivated by GTPase-activating proteins (GAPs) or by its intrinsic GTPase activity. This mechanism differs from that of previously reported oncogenic mutations that impair GTPase activity and GAP sensitivity without affecting nucleotide exchange. The constitutively active Gαo R243H mutant also enhances Src-STAT3 signaling in NIH-3T3 cells, a pathway previously shown to be directly triggered by active Gαo proteins to promote cellular transformation. Based on structural analyses, we propose that the enhanced rate of nucleotide exchange in Gαo R243H results from loss of the highly conserved electrostatic interaction of R243 with E43, located in the in the P-loop that represents the binding site for the α- and β-phosphates of the nucleotide. We conclude that the novel R234H mutation imparts oncogenic properties to Gαo by accelerating nucleotide exchange and rendering it constitutively active, thereby enhancing signaling pathways, for example, src-STAT3, responsible for neoplastic transformation.
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Affiliation(s)
- M Garcia-Marcos
- Department of Cellular and Molecular Medicine, San Diego School of Medicine, University of California, La Jolla, CA 92093-0651, USA.
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Miao ZM, Wang C, Wang BB, Meng DM, Su DM, Cheng Z, Wen QL, Han L, Yu Q, Ma X, Li CG. Identification of a novel mutation in a pseudohypoparathyroidism family. Int J Endocrinol 2011; 2011:509549. [PMID: 21822432 PMCID: PMC3142776 DOI: 10.1155/2011/509549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 05/23/2011] [Indexed: 12/17/2022] Open
Abstract
Pseudohypoparathyroidism type Ia (PHP Ia) is defined as a series of disorders characterized by multihormone resistance in end-organs and Albright hereditary osteodystrophy (AHO) phenotype. PHP Ia is caused by heterozygous inactivating mutations in GNAS, which encodes the stimulatory G-protein alpha subunit (Gsa). A patient with typical clinical manifestations of pseudohypoparathyroidism (PHP) (round face, short stature, centripetal obesity, brachydactyly, and multi-hormone resistance: parathyroid hormone (PTH), thyroid-stimulating hormone (TSH), and gonadotropins) presented at our center. The sequence of the GNAS gene from the patient and her families revealed a novel missense mutation (Y318H) in the proband and her mother. An in vitro Gsa functional study showed that Gsa function was significantly impaired. These results stress the importance of GNAS gene investigation.
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Affiliation(s)
- Zhi-Min Miao
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Can Wang
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Bin-Bin Wang
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Dong-Mei Meng
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Dong-Mei Su
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Zhi Cheng
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Qiao-Lian Wen
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Lin Han
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Qing Yu
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Xu Ma
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
- Center of Genetics, World Health Organization Collaborating Centre for Research in Human Reproduction, Beijing 100081, China
| | - Chang-Gui Li
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
- *Chang-Gui Li:
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15
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Abstract
Many proteins are S-acylated, affecting their localization and function. Dynamic S-acylation in response to various stimuli has been seen for several proteins in vivo. The regulation of S-acylation is beginning to be elucidated. Proteins can autoacylate or be S-acylated by protein acyl transferases (PATs). Deacylation, on the other hand, is an enzymatic process catalyzed by protein thioesterases (APT1 and PPT1) but only APT1 appears to be involved in the regulation of the reversible S-acylation of cytoplasmic proteins seen in vivo. PPT1, on the other hand, is involved in the lysosomal degradation of S-acylated proteins and PPT1 deficiency causes the disease infant neuronal ceroid lipofuscinosis.
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Affiliation(s)
- Ruth Zeidman
- Molecular Medicine, National Heart & Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, UK
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