Expression of contractile and cytoskeletal proteins in myocardium of patients with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is characterized by enlargement and dilation of all heart compartments associated with serious decrease of its contractile function. DCM hallmark is the combination of dystrophic and hypertrophic alterations of cardiomyocytes. Since the power output of cardiac cells is directly related to remodeling of their contractile machinery we investigated expression of selected contractile and cytoskeletal proteins in the left ventricle of DCM patients using immunoblotting. The content of the recognized protein markers of cardiomyocyte hypertrophy such as tubulin, desmin and slow skeletal myosin heavy chain isoform, MHCP, was significantly elevated in DCM compared to normal myocardium. in addition, marked increase in the content of several smooth muscle proteins (smooth muscle a-actin, Myosin Light Chain Kinase, Kinase Related protein SM22) that are normally expressed in embryonic myocardium, was observed in DCM hearts. Thus, cardiomyocyte hypertrophy in DCM is associated with activation of embryonic protein expression program and smooth muscle proteins could serve as markers of this process. Understanding their involvement in sarcomere assembly and pathways of their expression activation during cardiac hypertrophy may bring new insights in treatment of various forms of cardiomyopathy.