화학공학소재연구정보센터
Biochemical and Biophysical Research Communications, Vol.520, No.2, 327-332, 2019
The N-termini of GRK2 and GRK3 simulate the stimulating effects of RKIP on beta-adrenoceptors
The Raf kinase inhibitor protein (RKIP) activates beta-adrenoceptors (beta-AR) and thereby induces a well-tolerated cardiac contractility and prevents heart failure in mice. Different to RKIP-mediated beta-AR activation, chronic activation of beta-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 beta-AR phosphorylation and desensitization. Here, we evaluate RKIP-mediated effects on beta-AR to explore new strategies for beta-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 (GRK2(1-185) and GRK(3-185)). Overexpression of these N-termini prevented beta(2)-AR phosphorylation and internalization, subsequently increased receptor signaling in HEK293 cells and cardiomyocyte contractility. Co-immunoprecipitation assays of beta(2)-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 beta-AR signaling in HEK293 cells and in cardiomyocytes by their binding to beta(2)-AR and, thus, provide important insights for the development of new strategies to modulate beta(2)-AR signaling. (C) 2019 The Authors. Published by Elsevier Inc.