Bcl-2 targeted to the endoplasmic reticulum can inhibit apoptosis induced by Myc but not etoposide in Rat-1 fibroblasts

Oncogene. 1999 Jun 10;18(23):3520-8. doi: 10.1038/sj.onc.1202716.

Abstract

Bcl-2 is a key inhibitor of a broad range of apoptotic pathways, yet neither the mechanism of action nor the role of Bcl-2 subcellular localization are well understood. The subcellular localization of Bcl-2 includes the mitochondrial membrane as well as the contiguous membrane of the endoplasmic reticulum and nuclear envelope. Most studies suggest that the ability of Bcl-2 to confer cell survival is dependent upon its localization to the mitochondria. In this manuscript, we show that Bcl-2 targeted to the endoplasmic reticulum can inhibit Myc-, but not etoposide-induced apoptosis in the Rat-1 fibroblast cell line. By contrast, wild type Bcl-2 can inhibit apoptosis triggered by either death agonist. We further show both Myc and etoposide trigger disruption of mitochondrial membrane potential (MMP) and induce poly-ADP ribose polymerase (PARP) cleavage, but release of calcium was not evident. Bcl-2 abrogates apoptosis at or upstream of MMP depletion showing that Bcl-2 does not have to reside at the mitochondria to prevent apoptosis. These results further elucidate the biochemical events associated with Myc- and etoposide-induced apoptosis and significantly advance our understanding of Bcl-2 function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Phytogenic / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Calcium / metabolism
  • Caspases / physiology
  • Cell Line
  • Endoplasmic Reticulum / physiology*
  • Enzyme Activation
  • Etoposide / pharmacology
  • Intracellular Membranes / physiology
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Mitochondria / physiology
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-bcl-2 / physiology*
  • Proto-Oncogene Proteins c-myc / physiology
  • Rats

Substances

  • Antineoplastic Agents, Phytogenic
  • Nucleic Acid Synthesis Inhibitors
  • Proto-Oncogene Proteins c-bcl-2
  • Proto-Oncogene Proteins c-myc
  • Etoposide
  • Caspases
  • Calcium