The ubiquitin-proteasome system in cardiomyopathies.

PURPOSE OF REVIEW: Fine equilibrium between protein synthesis and protein degradation is essential for cell survival and function. After initial synthesis, membrane and secretory proteins are modified, folded, and assembled in the endoplasmic reticulum, whereas other proteins are synthesized and processed in the cytosol. Proteins are subject to different quality control systems to minimize aberrant production that could lead to cellular damage. The molecular chaperones help protein folding and stabilization, whereas the ubiquitin-proteasome system (UPS) and lysosomes degrade proteins. The UPS has been increasingly recognized as a major system involved in several biological processes such as cell proliferation, adaptation to stress and cell death.

RECENT FINDINGS: A number of studies have recently outlined the functional significance of the UPS in cardiovascular physiology and disease. Particularly, activation or impairment of the UPS has been reported in cardiac disease such as cardiac hypertrophy, myocardial ischemia and heart failure. Recent evidence indicates that the UPS plays a pathogenic role in hypertrophic cardiomyopathy and desmin-related cardiomyopathy.

SUMMARY: Since the clinical importance of the UPS is rapidly expanding, it has emerged as a potential target for therapy of cardiac disease.