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08:35

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Bcl-2 proteins regulate ER membrane permeability to luminal proteins during ER stress-induced apoptosis

X Wang1, K E Olberding, C White

  • 1Molecular Targets Group, James Graham Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY 40202, USA.

Cell Death and Differentiation
|June 12, 2010
PubMed

Insights

Endoplasmic reticulum (ER) stress triggers apoptosis by increasing ER membrane permeability. Proapoptotic Bcl-2 proteins like Bax facilitate this, releasing ER proteins into the cytosol.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Endoplasmic reticulum (ER) stress is implicated in apoptosis from various stimuli.
  • The precise molecular mechanisms linking ER stress to apoptosis remain incompletely understood.
  • The Bcl-2 protein family plays a critical role in regulating apoptosis.

Purpose of the Study:

  • To investigate the role of Bcl-2 family proteins in ER stress-induced apoptosis.
  • To elucidate the mechanism of ER luminal protein release during ER stress.
  • To determine how ER membrane permeability is regulated in this context.

Main Methods:

  • Utilized fluorescent protein reporters localized to the ER lumen.
  • Induced ER stress using pharmacological agents.
  • Assessed protein translocation and ER membrane association via cell imaging and biochemical assays.
  • Investigated in vitro ER membrane permeability changes mediated by specific Bcl-2 proteins.

Main Results:

  • ER stress induced the release of ER luminal proteins into the cytosol, dependent on Bax and Bak.
  • Bax translocated to and anchored at the ER membrane during ER stress.
  • Bax and truncated-Bid (tBid) increased ER membrane permeability to luminal proteins in vitro.
  • Antiapoptotic Bcl-X(L) counteracted the proapoptotic effects of Bax and tBid on ER membrane permeability.

Conclusions:

  • Bcl-2 protein family members regulate ER membrane permeability.
  • This regulation of ER membrane permeability by Bcl-2 proteins represents a key molecular mechanism in ER stress-induced apoptosis.
  • Targeting Bcl-2 protein interactions with the ER membrane could offer therapeutic strategies for ER stress-related diseases.

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