Phosphorylation and desensitization of human endothelin A and B receptors. Evidence for G protein-coupled receptor kinase specificity
| Autor: | N J, Freedman, A S, Ament, M, Oppermann, R H, Stoffel, S T, Exum, R J, Lefkowitz |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
G-Protein-Coupled Receptor Kinase 5
Endothelin-1 Receptors Endothelin Receptor Protein-Tyrosine Kinases Protein Serine-Threonine Kinases G-Protein-Coupled Receptor Kinases Phosphatidylinositols Receptor Endothelin A Cyclic AMP-Dependent Protein Kinases Receptor Endothelin B Cell Line Rats Substrate Specificity Molecular Weight Models Chemical GTP-Binding Proteins beta-Adrenergic Receptor Kinases Animals Humans Cattle Phosphorylation |
| Zdroj: | The Journal of biological chemistry. 272(28) |
| ISSN: | 0021-9258 |
| Popis: | Although endothelin-1 can elicit prolonged physiologic responses, accumulating evidence suggests that rapid desensitization affects the primary G protein-coupled receptors mediating these responses, the endothelin A and B receptors (ETA-R and ETB-R). The mechanisms by which this desensitization proceeds remain obscure, however. Because some intracellular domain sequences of the ETA-R and ETB-R differ substantially, we tested the possibility that these receptor subtypes might be differentially regulated by G protein-coupled receptor kinases (GRKs). Homologous, or receptor-specific, desensitization occurred within 4 min both in the ETA-R-expressing A10 cells and in 293 cells transfected with either the human ETA-R or ETB-R. In 293 cells, this desensitization corresponded temporally with agonist-induced phosphorylation of each receptor, assessed by receptor immunoprecipitation from 32Pi-labeled cells. Agonist-induced receptor phosphorylation was not substantially affected by PKC inhibition but was reduced 40% (p0.03) by GRK inhibition, effected by a dominant negative GRK2 mutant. Inhibition of agonist-induced phosphorylation abrogated agonist-induced ETA-R desensitization. Overexpression of GRK2, -5, or -6 in 293 cells augmented agonist-induced ET-R phosphorylation approximately 2-fold (p0.02), but each kinase reduced receptor-promoted phosphoinositide hydrolysis differently. While GRK5 inhibited ET-R signaling by only approximately 25%, GRK2 inhibited ET-R signaling by 80% (p0.01). Congruent with its superior efficacy in suppressing ET-R signaling, GRK2, but not GRK5, co-immunoprecipitated with the ET-Rs in an agonist-dependent manner. We conclude that both the ETA-R and ETB-R can be regulated indistinguishably by GRK-initiated desensitization. We propose that because of its affinity for ET-Rs demonstrated by co-immunoprecipitation, GRK2 is the most likely of the GRKs to initiate ET-R desensitization. |
| Databáze: | OpenAIRE |
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