The role of CaM Kinase II in cardiac function in health and disease

Abstract

Ca2+-calmodulin-dependent protein kinase II (CaMKII) has emerged as a critical molecule involved in the regulation of cell processes that are dependent on calcium, including excitation-contraction coupling (ECC), cell growth, and death. In addition to a generally accepted signaling pathway through beta-adrenergic receptors (ARs), oxidative stress has been suggested to promote CaMKII activation. Since many cardiac diseases, including those characterized by a phenomenon called as ischemia/reperfusion injury (IRI), are associated with oxidative stress, CaMKII is likely to be a crucial molecule underlying the phenotypes of this cardiac injury. In contrast, there is also evidence that CaMKII activation leading to phosphorylation of phospholamban and the subsequent decrease of calcium overload is important for attenuation of post-ischemic cardiac contracture, indicating that CaMKII may act as a double-edged sword depending on the actual conditions. In addition, CaMKII over-activation has been shown to destabilize the action potential and trigger early and delayed afterdepolarizations promoting arrhythmias. Experimental studies from our laboratory have revealed that CaMKII inhibition does not protect the heart against all types of IRI-induced ventricular arrhythmias, but it is capable to reduce the occurrence of the most life-threatening tachyarrhythmias. Moreover, the CaMKII inhibition appears to reduce oxidative stress and thus to increase the viability of cardiomyocytes upon IRI. In this manuscript, a dual role of CaMKII in IRI is reviewed and beneficial effects of the CaMKII inhibition are discussed with studies that have shown the opposite results.