Scaffolding protein Homer 1c mediates hypertrophic responses downstream of Gq in cardiomyocytes

摘要: Activation of the heterotrimeric G protein, Gq, causes cardiomyocyte hypertrophy in vivo and cell models. Responses to activated Gq cardiomyocytes are mediated exclusively by phospholipase Cβ1b (PLCβ1b), because it localizes at sarcolemma binding Shank3, a high-molecular-weight (MW) scaffolding protein. Shank3 can bind Homer family low-MW proteins that fine tune Ca2+ signaling facilitating crosstalk between channels surface with those on intracellular stores. α1-adrenergic receptors, expression constitutively active Gαq (GαqQL), or PLCβ1b initiated increased 1c mRNA expression, 1.6 ± 0.18-, 1.9 0.17-, 1.5 0.07-fold, respectively (means se, 6 independent experiments, P<0.05). Expression induced an increase area from 853 27 1146 31 μm2 (P<0.05); furthermore, dominant-negative (Homer 1a) reversed size caus...