Abstract 18468: ERK-Mediated Phosphorylation of GRK2 at Ser 670 is Essential for its Hsp90-dependent, Stress-Activated Mitochondrial Localization

Background: G protein-coupled receptor (GPCR) kinase-2 (GRK2) regulates intracellular signaling via phosphorylation of agonist-occupied GPCRs. Identification of novel binding partners for GRK2, including heat shock protein 90 (Hsp90), point towards additional cellular roles for GRK2. We have found that GRK2 associates with mitochondria (Mito) and tested the hypothesis that GRK2 binding to Hsp90 regulates its stress-induced Mito translocation. Methods: Oxidative stress in myocytes was induced by treatment with chelerythrin (Chele) and ischemia/reperfusion (IR) was used in vivo in mice. Whole cell lysates and Mito fractions were prepared from cells or hearts. Immunoprecipitation (IP) and Western blotting was conducted to examine binding of GRK2 to Hsp90 and Mito translocation of these proteins. Direct in vitro binding of Hsp90 and GRK2 was studied using fusion proteins. To study the role of Ser670, a site for ERK phosphorylation, in stress-dependent GRK2 Mito translocation, a site-specific, phospho-antibody...