Inhibition of protein kinase C βII isoform ameliorates methylglyoxal advanced glycation endproduct-induced cardiomyocyte contractile dysfunction

Abstract

AimsAccumulation of advanced glycation endproduct (AGE) contributes to diabetic complication including diabetic cardiomyopathy although the precise underlying mechanism still remains elusive. Recent evidence depicted a pivotal role of protein kinase C (PKC) in diabetic complications. To this end, this study was designed to examine if PKCβII contributes to AGE-induced cardiomyocyte contractile and intracellular Ca2+ aberrations. Main methodsAdult rat cardiomyocytes were incubated with methylglyoxal-AGE (MG-AGE) in the absence or presence of the PKCβII inhibitor LY333531 for 12h. Contractile and intracellular Ca2+ properties were assessed using an IonOptix system including peak shortening (PS), maximal velocity of shortening/relengthening (±dL/dt), time-to-PS (TPS), time-to-90% relengthening (TR90), rise in intracellular Ca2+ Fura-2 fluorescence intensity and intracellular Ca2+ decay. Oxidative stress, O2− production and mitochondrial integrity were examined using TBARS, fluorescence imaging, aconitase activity and Western blotting. Key findingsMG-AGE compromised contractile and intracellular Ca2+ properties including reduced PS, ±dL/dt, prolonged TPS and TR90, decreased electrically stimulated rise in intracellular Ca2+ and delayed intracellular Ca2+ clearance, the effects of which were ablated by the PKCβII inhibitor LY333531. Inhibition of PKCβII rescued MG-AGE-induced oxidative stress, O2− generation, cell death, apoptosis and mitochondrial injury (reduced aconitase activity, UCP-2 and PGC-1α). In vitro studies revealed that PKCβII inhibition-induced beneficial effects were replicated by the NADPH oxidase inhibitor apocynin and were mitigated by the mitochondrial uncoupler FCCP. SignificanceThese findings implicated the therapeutic potential of specific inhibition of PKCβII isoform in the management of AGE accumulation-induced myopathic anomalies.