SUBCELLULAR-LOCALIZATION OF THE BCL-2 PROTEIN IN MALIGNANT AND NORMALLYMPHOID-CELLS

The bcl-2 oncogene is expressed in lymphoid and myeloid cells as well as in neurons and several types of epithelial cells and inhibits progr ammed cell death (apoptosis). Deregulation by the t(14;18) translocati on in lymphoid malignancies induces inappropriate cell survival and se rves as one of the steps toward a fully malignant behavior. Using pre- and postembedding immunoelectron microscopy in normal and neoplastic lymphocytes, we demonstrate bcl-2 immunoreactivity to the mitochondria l outer circumference and the nuclear envelope and to a lesser degree to the cell membrane. Mitochondrial staining was patchy reminiscent of mitochondrial contact zones. Additionally, there was a suggestion of association with nuclear pores. In these regions, transmembrane transp ort is mediated. This may suggest that bcl-2 exerts its function in th is process.