The Palmitoyl Acyltransferase DHHC5 Mediates Beta-Adrenergic Signaling in the Heart by Targeting G Alpha Proteins

S-palmitoylation is a reversible posttranslational modification that plays an important role in regulating protein localization, trafficking, and stability. Recent studies have shown that some proteins undergo extremely rapid palmitoylation/depalmitoylation cycles after cellular stimulation supporting a direct signaling role for this posttranslational modification. Here we investigated whether beta-adrenergic stimulation of cardiomyocytes led to stimulus-dependent palmitoylation of downstream signaling proteins. We found that beta-adrenergic stimulation led to increased Gas and Gai palmitoylation. The kinetics of palmitoylation was temporally consistent with the downstream production of cAMP and positive inotropic responses. Additionally, we identified for the first time that G protein-coupled receptor kinase 2 (GRK2) is a palmitoylated protein in cardiomyocytes. The kinetics of GRK2 palmitoylation were distinct from those observed with Gas and Gai after beta-adrenergic stimulation. Knockdown of the plasma membrane-localized palmitoyl acyltransferase DHHC5 revealed that this enzyme is necessary for palmitoylation of Gas and Gai and functional responses downstream of beta-adrenergic stimulation. Additionally, in vitro assays using purified components identify Gas and Gai proteins as direct substrates of DHHC5. Our results reveal that DHHC5 activity is required for signaling downstream of beta-adrenergic receptors in the heart