APOPTOSIS-ASSOCIATED PROTEOLYSIS OF VIMENTIN IN HUMAN PROSTATE EPITHELIAL TUMOR-CELLS

Vimentin intermediate filaments (IF) are responsible for regulation of cell attachment and subcellular organization. Using an in vitro model system of human prostate epithelial cells (267B1-XR), we demonstrate that a series of vimentin proteolytic fragments represent some of the differentially expressed proteins in 2D-gel profiles of the apoptotic cells undergoing ionizing radiation-induced cell death. A caspase-sens itive motif search suggests that the type III IF protein (vimentin) is subject to proteolysis to promote the execution phase of apoptosis, i n a manner similar to the well-established type V (lamins) and type I (keratins 18, 19) IF proteins. Furthermore, vimentin and a few of its derived polypeptides, reported to be specific to the apoptotic process , correspond to ubiquinated proteins, thus pointing to the complex int errelationships of protein ubiquination in solubilizing the IF network during apoptosis. (C) 1998 Academic Press.