title: Cellular localization of the bcl-2 protein and response to glucocorticoid stress.
abstract: We performed immunoelectronmicroscopy, immunofluorescence and subcellular fractionation studies of insect cells (Spodopetra frugiperda or SF9) infected with recombinant baculovirus containing bcl-2 cDNA to determine the cellular localization of the bcl-2 product. Similar studies were also undertaken in pre-B cells carrying a bcl-2 gene activated by t(14;18) chromosomal translocation. By immunogold electron microscopy, bcl-2 was localized at several intracellular sites including the nuclear membrane, endoplasmic reticulum, mitochondria and plasma membrane. Immunofluorescence studies revealed the presence of the bcl-2 product throughout the cytoplasm, whereas biochemical fractionation studies indicated a similar pattern to that observed on electron microscopy. Our investigation clearly indicates that the bcl-2 product is expressed at several intracellular sites. Studies were also undertaken to determine any changes in the subcellular distribution of bcl-2 protein following glucocorticoid exposure of immature B lymphocytes. Although no major changes in the distribution of bcl-2 protein were observed, more aggregated patches of gold labelled bcl-2 particles were found under glucocorticoid stress. Aggregation of bcl-2 molecules might represent dimerization necessary to prevent apoptosis.
authors.affiliation: Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: S
authors.initials: S
authors.lastname: Haldar
authors.forename: N
authors.initials: N
authors.lastname: Jena
authors.forename: R
authors.initials: R
authors.lastname: Coss
authors.forename: A W
authors.initials: AW
authors.lastname: Sedar
authors.forename: P R
authors.initials: PR
authors.lastname: Wachsberger
authors.forename: C
authors.initials: C
authors.lastname: Beatty
authors.forename: C M
authors.initials: CM
authors.lastname: Croce