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In vivo evidence that caspase-3 is required for Fas-mediated apoptosis of hepatocytes

M Woo1, A Hakem, A J Elia

  • 1Amgen Institute, Ontario Cancer Institute, University of Toronto, Canada.

Journal of Immunology (Baltimore, Md. : 1950)
|October 21, 1999
PubMed

Insights

Caspase-3 deficiency delays Fas-mediated hepatocyte death in vivo. Intact Bcl-2 in caspase-3-/- mice prevents cytochrome c release, highlighting caspase-3

Area of Science:

  • Molecular Biology
  • Immunology
  • Cell Death Research

Background:

  • Caspase-3 is a key executioner in apoptosis in vitro.
  • Its precise role in Fas-mediated apoptosis in vivo remains incompletely understood.
  • Fas-mediated apoptosis is critical for immune regulation and tissue homeostasis.

Purpose of the Study:

  • To investigate the in vivo role of caspase-3 in Fas-mediated hepatocyte apoptosis.
  • To determine if caspase-3 regulates upstream apoptotic proteins in Fas signaling.

Main Methods:

  • Administration of agonistic anti-Fas antibody to wild-type and caspase-3-deficient mice.
  • Assessment of hepatocyte cell death, survival rates, and liver injury.
  • Western blot analysis of Bcl-2, Bcl-xL, caspase-9, caspase-8, Bid, and cytochrome c.
  • Analysis of protein processing and subcellular localization of cytochrome c.

Main Results:

  • Caspase-3 deficient mice exhibited delayed hepatocyte death and increased survival following anti-Fas Ab injection.
  • Wild-type mice showed decreased Bcl-2 expression and cytochrome c release, unlike caspase-3 deficient mice.
  • Caspase-3 deficiency prevented the cleavage of Bcl-2, Bcl-xL, caspase-9, caspase-8, and Bid.

Conclusions:

  • Caspase-3 plays a crucial role in regulating Fas-mediated apoptosis in vivo.
  • Beyond its effector function, caspase-3 processes upstream regulatory proteins like Bcl-2, impacting mitochondrial pathways.
  • This study reveals a novel upstream regulatory function for caspase-3 in Fas-mediated cell death.

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