Regulation of corticotropin-releasing hormone receptor type 1 alpha signaling: Structural determinants for G protein-coupled receptor kinase-mediated phosphorylation and agonist-mediated desensitization
UNSPECIFIED. (2005) Regulation of corticotropin-releasing hormone receptor type 1 alpha signaling: Structural determinants for G protein-coupled receptor kinase-mediated phosphorylation and agonist-mediated desensitization. MOLECULAR ENDOCRINOLOGY, 19 (2). pp. 474-490. ISSN 0888-8809Full text not available from this repository.
Official URL: http://dx.doi.org/10.1210/me.2004-0275
Attenuation of CRH receptor type 1 (CRH-R1) signaling activity might involve desensitization and uncoupling of CRH-R1 from intracellular effectors. We investigated the desensitization of native CRH-R in human myometrial cells from pregnant women and recombinant CRH-R1alpha stably overexpressed in human embryonic kidney (HEK) 293 cells. In both cell types, CRH-R1-mediated adenylyl cyclase activation was susceptible to homologous desensitization induced by pretreatment with high concentrations of CRH. Time course studies showed half-maximal desensitization occurring after approximately 40 min of pretreatment and full recovery of CRH-R1alpha functional response within 2 h of removal of CRH pretreatment. In HEK 293 cells, desensitization of CRH-R1alpha was associated with receptor phosphorylation and subsequent endocytosis. To analyze the mechanism leading to CRH-R1alpha desensitization, we overexpressed a truncated beta-arrestin (319-418) and performed coimmunoprecipitation and G protein-coupled receptor kinase (GRK) translocation studies. We found that GRK3 and GRK6 are the main isoforms that interact with CRH-R1alpha, and that recruitment of GRK3 requires Gbetagamma-subunits as well as beta-arrestin. Site-directed mutagenesis of Ser and Thr residues in the CRH-R1alpha C terminus, identified Thr(399) as important for GRK-induced receptor phosphorylation and desensitization. We conclude that homologous desensitization of CRH-R1alpha involves the coordinated action of multiple GRK isoforms, Gbeta gamma dimers and beta-arrestin. Based on our identification of key amino acid(s) for GRK-dependent phosphorylation, we demonstrate the importance of the CRH-R1alpha carboxyl tail for regulation of receptor activity.
|Item Type:||Journal Article|
|Subjects:||R Medicine > RC Internal medicine|
|Journal or Publication Title:||MOLECULAR ENDOCRINOLOGY|
|Number of Pages:||17|
|Page Range:||pp. 474-490|
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