ER Stress Triggers Apoptosis by Activating BH3-only Protein Bim

Cell. 2007 Jun 29;129(7):1337-49. doi: 10.1016/j.cell.2007.04.027.

Abstract

Endoplasmic reticulum (ER) stress caused by misfolded proteins or cytotoxic drugs can kill cells and although activation of this pathway has been implicated in the etiology of certain degenerative disorders its mechanism remains unresolved. Bim, a proapoptotic BH3-only member of the Bcl-2 family is required for initiation of apoptosis induced by cytokine deprivation or certain stress stimuli. Its proapoptotic activity can be regulated by several transcriptional or posttranslational mechanisms, such as ERK-mediated phosphorylation, promoting its ubiquitination and proteasomal degradation. We found that Bim is essential for ER stress-induced apoptosis in a diverse range of cell types both in culture and within the whole animal. ER stress activates Bim through two novel pathways, involving protein phosphatase 2A-mediated dephosphorylation, which prevents its ubiquitination and proteasomal degradation and CHOP-C/EBPalpha-mediated direct transcriptional induction. These results define the molecular mechanisms of ER stress-induced apoptosis and identify targets for therapeutic intervention in ER stress-related diseases.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / physiology*
  • Apoptosis Regulatory Proteins / metabolism*
  • Bcl-2-Like Protein 11
  • Cells, Cultured
  • Endoplasmic Reticulum / drug effects
  • Endoplasmic Reticulum / metabolism*
  • Endoplasmic Reticulum / ultrastructure
  • Enzyme Inhibitors / pharmacology
  • Membrane Proteins / metabolism*
  • Mice
  • Phosphoprotein Phosphatases / metabolism
  • Phosphorylation
  • Protein Phosphatase 2
  • Protein Structure, Tertiary / physiology
  • Proto-Oncogene Proteins / metabolism*
  • Regulatory Elements, Transcriptional / physiology
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / antagonists & inhibitors
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Thapsigargin / pharmacology
  • Transcription Factor CHOP / genetics
  • Transcription Factor CHOP / metabolism
  • Up-Regulation / drug effects
  • Up-Regulation / physiology

Substances

  • Apoptosis Regulatory Proteins
  • Bcl-2-Like Protein 11
  • Bcl2l11 protein, mouse
  • Enzyme Inhibitors
  • Membrane Proteins
  • Proto-Oncogene Proteins
  • Transcription Factor CHOP
  • Thapsigargin
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 2
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases