Redistribution of Sarcomeric Myosin and α-Actinin in Cardiomyocytes in Culture upon the Rearrangement of their Contractile Apparatus

Abstract

Cardiomyocytes in culture undergo reversible rearrangement of their contractile apparatus with conversion of typical myofibrils into structures resembling stress fibers of nonmuscle cells. Such rearrangement is accompanied by the replacement of cardiac actin, the main protein of myofibrils, with its smooth muscle isoform. This study shows that along with the replacement of actin isoform the key structural sarcomeric proteins are released from actin structures and stored in cell cytoplasm as inclusions not bound with actin. The data obtained are indicative of the incompatibility of smooth muscle actin with sarcomeric isoforms of these proteins and myofibrillar organization in general.