The N-termini of GRK2 and GRK3 simulate the stimulating effects of RKIP on ß-adrenoceptors.
Biochem Biophys Res Commun
; 520(2): 327-332, 2019 12 03.
Article
em En
| MEDLINE
| ID: mdl-31604529
ABSTRACT
The Raf kinase inhibitor protein (RKIP) activates ß-adrenoceptors (ß-AR) and thereby induces a well-tolerated cardiac contractility and prevents heart failure in mice. Different to RKIP-mediated ß-AR activation, chronic activation of ß-AR by catecholamines was shown to be detrimental for the heart. RKIP is an endogenous inhibitor of G protein coupled receptor kinase 2 (GRK2); it binds GRK2 and thereby inhibits GRK2 mediated ß-AR phosphorylation and desensitization. Here, we evaluate RKIP-mediated effects on ß-AR to explore new strategies for ß-AR modulation. Co-immunoprecipitation assays and pull-down assays revealed subtype specificity of RKIP for the cardiac GRK isoforms GRK2 and GRK3 - not GRK5 - as well as several RKIP binding sites within their N-termini (GRK21-185 and GRK31-185). Overexpression of these N-termini prevented ß2-AR phosphorylation and internalization, subsequently increased receptor signaling in HEK293â¯cells and cardiomyocyte contractility. Co-immunoprecipitation assays of ß2-AR with these N-terminal GRK fragments revealed a direct interaction suggesting a steric interference of the fragments with the functional GRK-receptor interaction. Altogether, N-termini of GRK2 and GRK3 efficiently simulate RKIP effects on ß-AR signaling in HEK293â¯cells and in cardiomyocytes by their binding to ß2-AR and, thus, provide important insights for the development of new strategies to modulate ß2-AR signaling.
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MEDLINE
Assunto principal:
Receptores Adrenérgicos beta 2
/
Quinase 2 de Receptor Acoplado a Proteína G
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Quinase 3 de Receptor Acoplado a Proteína G
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article