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 viability by preventing the activation of the cell death effectors, the caspases. Gene targeting experiments in mice have demonstrated that Bcl-W is required for spermatogenesis and for survival of damaged epithelial cells in the gut. Bcl-W is, however, dispensable for physiological cell death in Other 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 fractionation and confocal laser scanning microscopy demonstrated that Bcl-W protein is associated with intracellular membranes. The implications of these results are discussed in the context of the phenotype of Bcl-w-null mice and recent data that suggest that Bcl-W may play a role in colon carcinogenesis.