Claudia Saglia, Francesca Arruga, Caterina Scolari, Silvia Kalantari, Serena Albanese, Valeria Bracciamà, Angelo Corso Faini, Giulia Brach Del Prever, Maria Luca, Carmelo Romeo, Fiorenza Mioli, Martina Migliorero, Daniele Tessaris, Diana Carli, Antonio Amoroso, Tiziana Vaisitti, Luisa De Sanctis, Silvia Deaglio
{"title":"对导致低钙血症的 CASR 基因新型无义变体进行功能评估。","authors":"Claudia Saglia, Francesca Arruga, Caterina Scolari, Silvia Kalantari, Serena Albanese, Valeria Bracciamà, Angelo Corso Faini, Giulia Brach Del Prever, Maria Luca, Carmelo Romeo, Fiorenza Mioli, Martina Migliorero, Daniele Tessaris, Diana Carli, Antonio Amoroso, Tiziana Vaisitti, Luisa De Sanctis, Silvia Deaglio","doi":"10.1093/ejendo/lvae035","DOIUrl":null,"url":null,"abstract":"<p><strong>Objective: </strong>The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants.</p><p><strong>Design and methods: </strong>To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs.</p><p><strong>Results: </strong>Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT.</p><p><strong>Conclusions: </strong>This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.</p>","PeriodicalId":11884,"journal":{"name":"European Journal of Endocrinology","volume":null,"pages":null},"PeriodicalIF":5.3000,"publicationDate":"2024-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Functional evaluation of a novel nonsense variant of the calcium-sensing receptor gene leading to hypocalcemia.\",\"authors\":\"Claudia Saglia, Francesca Arruga, Caterina Scolari, Silvia Kalantari, Serena Albanese, Valeria Bracciamà, Angelo Corso Faini, Giulia Brach Del Prever, Maria Luca, Carmelo Romeo, Fiorenza Mioli, Martina Migliorero, Daniele Tessaris, Diana Carli, Antonio Amoroso, Tiziana Vaisitti, Luisa De Sanctis, Silvia Deaglio\",\"doi\":\"10.1093/ejendo/lvae035\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><strong>Objective: </strong>The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants.</p><p><strong>Design and methods: </strong>To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs.</p><p><strong>Results: </strong>Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT.</p><p><strong>Conclusions: </strong>This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.</p>\",\"PeriodicalId\":11884,\"journal\":{\"name\":\"European Journal of Endocrinology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":5.3000,\"publicationDate\":\"2024-03-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"European Journal of Endocrinology\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1093/ejendo/lvae035\",\"RegionNum\":1,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENDOCRINOLOGY & METABOLISM\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"European Journal of Endocrinology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1093/ejendo/lvae035","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENDOCRINOLOGY & METABOLISM","Score":null,"Total":0}
Functional evaluation of a novel nonsense variant of the calcium-sensing receptor gene leading to hypocalcemia.
Objective: The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants.
Design and methods: To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs.
Results: Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT.
Conclusions: This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.
期刊介绍:
European Journal of Endocrinology is the official journal of the European Society of Endocrinology. Its predecessor journal is Acta Endocrinologica.
The journal publishes high-quality original clinical and translational research papers and reviews in paediatric and adult endocrinology, as well as clinical practice guidelines, position statements and debates. Case reports will only be considered if they represent exceptional insights or advances in clinical endocrinology.
Topics covered include, but are not limited to, Adrenal and Steroid, Bone and Mineral Metabolism, Hormones and Cancer, Pituitary and Hypothalamus, Thyroid and Reproduction. In the field of Diabetes, Obesity and Metabolism we welcome manuscripts addressing endocrine mechanisms of disease and its complications, management of obesity/diabetes in the context of other endocrine conditions, or aspects of complex disease management. Reports may encompass natural history studies, mechanistic studies, or clinical trials.
Equal consideration is given to all manuscripts in English from any country.