PKC translocation without changes in Gαq and PLC-β protein abundance in cardiac hypertrophy and failure

Activation of protein kinase C (PKC) has been implicated as playing a Bey role in the pathogenesis of cardiac hypertrophy This study investigates the response of several signal transduction proteins responsible for PKC activation during the transition from compensated pressure-overload hypertrophy (POH) to congestive heart failure (CHF). Pressure overload was produced on male, adult, Hartley strain guinea pigs using a ligature around the descending thoracic aorta. Sham-operated controls, POH, and CHF groups were identified based on left ventricular hypertrophy, pulmonary congestion, and isolated heart Langendorff mechanics. Quantitative immunoblotting revealed phospholipase C (PLC)-beta I and G alpha(q) were unchanged during POH and CHF, as were RGS2, RGS3, and RGS4 (regulators of G protein signaling, which are activators of intrinsic GTPase activity). Translocation of PKC-alpha, -epsilon, and -gamma from cytosolic to membranous fractions were significantly increased during POH and CHF. Cytosolic PKC activity was also elevated during POH. We conclude that differential PKC activation may be mediated by increases in G alpha(q) and PLC-beta I activity rather than upregulation of expression.