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Sequential activation of poly(ADP-ribose) polymerase 1, calpains, and Bax is essential in apoptosis-inducing

Rana S Moubarak1, Victor J Yuste, Cédric Artus

  • 1Apoptose et Système Immunitaire, CNRS-URA 1961, Institut Pasteur, 25 Rue du Dr. Roux, 75015 Paris, France.

Molecular and Cellular Biology
|May 2, 2007
PubMed

Insights

Alkylating DNA damage triggers programmed necrosis via poly(ADP-ribose) polymerases (PARP) and apoptosis-inducing factor (AIF). Calpains and Bax are essential links, with Bax being indispensable for this AIF-dependent cell death pathway.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Alkylating DNA damage can induce programmed cell death.
  • Poly(ADP-ribose) polymerases (PARP) and apoptosis-inducing factor (AIF) are implicated in this process.
  • The precise molecular mechanisms linking PARP activation to AIF-mediated necrosis are not fully understood.

Purpose of the Study:

  • To elucidate the molecular links between PARP activation and AIF-mediated necrosis.
  • To identify key proteins involved in the signaling pathway of alkylating DNA damage-induced cell death.
  • To investigate the role of Bax and calpains in this necrotic process.

Main Methods:

  • Utilized a large panel of gene knockout cells to identify essential molecular players.
  • Investigated the roles of PARP-1, PARP-2, calpains, cathepsins, caspases, Bax, Bak, and Bcl-2.
  • Examined AIF release from mitochondria and nuclear translocation.
  • Assessed cell death induction by N-methyl-N'-nitro-N'-nitrosoguanidine (MNNG).

Main Results:

  • Alkylating DNA damage induces p53-independent necrosis requiring PARP-1, but not PARP-2.
  • PARP-1 activation leads to mitochondrial AIF release and necrosis via calpains, independent of cathepsins and caspases.
  • Ablation of Bax, but not Bak, prevents AIF release and alkylating DNA damage-induced death, establishing Bax as indispensable.
  • Bcl-2 was found to regulate MNNG-induced necrosis.
  • The molecular order of activation was established: PARP-1, calpains, Bax, and AIF.
  • Downregulation of AIF confers resistance to this type of necrosis.

Conclusions:

  • Bax and calpains are critical mediators linking PARP-1 activation to AIF release and subsequent necrosis.
  • AIF-dependent necrosis is a highly regulated programmed cell death pathway, similar to apoptosis.
  • These findings provide new insights into the mechanisms governing programmed necrosis.

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