Activating Mutations of the G-protein Subunit αâ11 Interdomain Interface Cause Autosomal Dominant Hypocalcemia Type 2.
J Clin Endocrinol Metab
; 105(3)2020 03 01.
Article
em En
| MEDLINE
| ID: mdl-31820785
ABSTRACT
CONTEXT Autosomal dominant hypocalcemia types 1 and 2 (ADH1 and ADH2) are caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR) and its signaling partner, the G-protein subunit αâ11 (Gαâ11), respectively. More than 70 different gain-of-function CaSR mutations, but only 6 different gain-of-function Gαâ11 mutations are reported to date. METHODS:
We ascertained 2 additional ADH families and investigated them for CaSR and Gαâ11 mutations. The effects of identified variants on CaSR signaling were evaluated by transiently transfecting wild-type (WT) and variant expression constructs into HEK293 cells stably expressing CaSR (HEK-CaSR), and measuring intracellular calcium (Ca2+i) and MAPK responses following stimulation with extracellular calcium (Ca2+e).RESULTS:
CaSR variants were not found, but 2 novel heterozygous germline Gαâ11 variants, p.Gly66Ser and p.Arg149His, were identified. Homology modeling of these revealed that the Gly66 and Arg149 residues are located at the interface between the Gαâ11 helical and GTPase domains, which is involved in guanine nucleotide binding, and this is the site of 3 other reported ADH2 mutations. The Ca2+i and MAPK responses of cells expressing the variant Ser66 or His149 Gαâ11 proteins were similar to WT cells at low Ca2+e, but significantly increased in a dose-dependent manner following Ca2+e stimulation, thereby indicating that the p.Gly66Ser and p.Arg149His variants represent pathogenic gain-of-function Gαâ11 mutations. Treatment of Ser66- and His149-Gαâ11 expressing cells with the CaSR negative allosteric modulator NPS 2143 normalized Ca2+i and MAPK responses.CONCLUSION:
Two novel ADH2-causing mutations that highlight the Gαâ11 interdomain interface as a hotspot for gain-of-function Gαâ11 mutations have been identified.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP
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Receptores de Detecção de Cálcio
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Hipercalciúria
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Mutação com Ganho de Função
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Hipocalcemia
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Hipoparatireoidismo
Limite:
Adult
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Child
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Female
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Humans
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Male
Idioma:
En
Revista:
J Clin Endocrinol Metab
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Reino Unido