Overexpression of the G protein G11alpha prevents desensitization of Ca2+ response to thyrotropin-releasing hormone.
Life Sci
; 65(9): 889-900, 1999.
Article
em En
| MEDLINE
| ID: mdl-10465349
ABSTRACT
Doubly transfected human embryonal kidney cells (clone E2M11 of the HEK 293 cell line) expressing both thyrotropin-releasing hormone (TRH) receptors and G11alpha protein in high amounts were used to analyze the desensitization phenomenon of the Ca2+-mobilizing pathway. Quite unexpectedly, we did not observe any significant desensitization of the [Ca2+]i response to TRH in these cells after repeated or prolonged incubation with the hormone (up to 5 h). Under the same conditions, the TRH-induced [Ca2+]i response was completely desensitized in the parent cell line (293-E2 cels) expressing TRH receptors alone. In both cell lines, inositol phosphate response was desensitized after TRH exposure, although basal levels of inositol phospates in TRH-pretreated cells were much higher than in "naive" TRH-unexposed cells. These data suggest a significant role of the G protein G11alpha in desensitization of the Ca2+-mobilizing pathway occuring after repeated or long-term exposure of target cells to TRH-receptor agonists.
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Base de dados:
MEDLINE
Assunto principal:
Hormônio Liberador de Tireotropina
/
Receptores do Hormônio Liberador da Tireotropina
/
Proteínas de Ligação ao GTP
/
Sinalização do Cálcio
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article