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Examining BCL-2 Family Function with Large Unilamellar Vesicles
08:35

Examining BCL-2 Family Function with Large Unilamellar Vesicles

Published on: October 5, 2012

BCL-2, BCL-X(L) sequester BH3 domain-only molecules preventing BAX- and BAK-mediated mitochondrial apoptosis

E H Cheng1, M C Wei, S Weiler

  • 1Howard Hughes Medical Institute, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA 02115, USA.

Molecular Cell
|October 5, 2001
PubMed

Insights

Cellular apoptosis critical issues involve caspases versus organelle dysfunction. Our study reveals BH3 domain-only molecules activate BAX and BAK, initiating a mitochondrial pathway crucial for cell death.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Apoptosis regulation involves complex interplay between caspases, organelle dysfunction, and BCL-2 family members.
  • Key questions remain regarding the relative importance of caspases versus mitochondrial dysfunction and the timing of commitment to cell death.

Purpose of the Study:

  • To elucidate the roles of downstream caspases and upstream BCL-2 family members in initiating apoptosis.
  • To determine the mechanism by which BH3 domain-only molecules trigger cell death pathways.

Main Methods:

  • Analysis of cells deficient in downstream apoptotic effectors (Apaf-1, Caspase-9, Caspase-3).
  • Assessment of resistance in cells lacking upstream multidomain BAX and BAK to various BH3 domain-only molecules.
  • Investigation of BCL-2 and BCL-X(L) interactions with BH3 domain-only molecules in mitochondrial complexes.

Main Results:

  • Cells lacking downstream caspases showed transient protection and caspase-independent death via mitochondrial dysfunction.
  • Cells lacking upstream BAX and BAK exhibited long-term resistance to all BH3 domain-only molecules.
  • Antiapoptotic BCL-2 proteins sequester BH3 domain-only molecules, inhibiting BAX and BAK activation.

Conclusions:

  • BH3 domain-only molecules activate multidomain proapoptotic proteins (BAX, BAK) to initiate a mitochondrial cell death pathway.
  • This pathway results in both cytochrome c release for caspase activation and caspase-independent mitochondrial dysfunction.
  • The findings clarify the central role of the mitochondrial pathway in mammalian apoptosis.

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