Tissue expression and subcellular localization of the pro-survival molecule Bcl-w

Anti-apoptotic members of the Bcl-2 family, such as Bcl-w, maintain cell vi ability by preventing the activation of the cell death effectors, the caspa ses, Gene targeting experiments in mice have demonstrated that Bcl-w is req uired for spermatogenesis and for survival of damaged epithelial cells in t he gut. Bcl-w is, however, dispensable for physiological cell death in othe r tissues. Here we report on the analysis of Bcl-w protein expression using a panel of novel monoclonal antibodies. Bcl-w is found In a diverse range of tissues including colon, brain and testes, A survey of transformed cell lines and purified hematopoietic cells demonstrated that Bcl-w is expressed in cells of myeloid, lymphoid and epithelial origin. Subcellular fractiona tion and confocal laser scanning microscopy demonstrated that Bcl-w protein is associated with intracellular membranes. The implications of these resu lts are discussed in the context of the phenotype of Bcl-w-null mice and re cent data that suggest that Bcl-w may play a role in colon carcinogenesis.