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Granzyme F induces a novel death pathway characterized by Bid-independent cytochrome c release without caspase

L Shi1, L Wu, S Wang

  • 1National Laboratory of Biomacromolecules and Center for Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.

Cell Death and Differentiation
|August 1, 2009
PubMed

Insights

Granzyme F (GzmF) triggers a unique cell death pathway in mice, distinct from apoptosis. This pathway involves mitochondrial damage and caspase inactivation, offering new insights into immune cell function.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • Granzyme F (GzmF) is a unique mouse granzyme highly expressed in NK3.1 and lymphokine-activated killer (LAK) cells.
  • The precise mechanism of GzmF in granule-mediated cytolysis remains largely unknown.

Purpose of the Study:

  • To elucidate the novel cell death pathway induced by Granzyme F.
  • To investigate the molecular mechanisms underlying GzmF-mediated cytotoxicity.

Main Methods:

  • Characterization of cell death markers including phosphatidylserine externalization, nuclear condensation, and mitochondrial damage.
  • Analysis of caspase activity, cytochrome c release, and DNA nicking.
  • Assessment of GzmF's impact on mitochondrial electron transport and ATP generation.
  • Evaluation of cytotoxicity in GzmF-silenced LAK cells.

Main Results:

  • GzmF induces a novel cell death pathway characterized by phosphatidylserine externalization, nuclear condensation, mitochondrial damage, cytochrome c release, and caspase inactivation.
  • GzmF-induced death exhibits features of necroptosis, including vacuolization and incomplete chromatin condensation.
  • Mitochondrial dysfunction, including swelling, depolarization, and reactive oxygen species accumulation, is observed.
  • Cytochrome c release is independent of Bid or Bax/Bak.
  • GzmF impairs mitochondrial electron transport, leading to ATP depletion and subsequent caspase inactivation, independent of apoptosome formation.

Conclusions:

  • Granzyme F initiates a distinct cell death pathway that differs from classical apoptosis and necroptosis.
  • GzmF-mediated cytotoxicity relies on mitochondrial impairment and subsequent ATP depletion, leading to caspase inactivation.
  • Understanding this novel pathway provides insights into immune surveillance and potential therapeutic strategies targeting GzmF.

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