DIABLO promotes apoptosis by removing MIHA/XIAP from processed caspase 9

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P G Ekert1, J Silke, C J Hawkins

  • 1The Walter and Eliza Hall Institute, The Royal Melbourne Hospital, Victoria 3050, Australia.

The Journal of Cell Biology
|February 7, 2001
PubMed

Insights

MIHA, an inhibitor of apoptosis protein, prevents cell death by blocking caspase activation. However, DIABLO binding disrupts this inhibition, allowing apoptosis to proceed, revealing a key regulatory mechanism in cell death pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Apoptosis Research

Background:

  • Inhibitors of Apoptosis Proteins (IAPs) regulate cell death by interacting with caspases.
  • DIABLO is a mammalian protein that antagonizes IAP function, similar to Drosophila proapoptotic factors.
  • Understanding IAP-DIABLO interactions is crucial for deciphering apoptosis regulation.

Purpose of the Study:

  • To investigate the role of MIHA in apoptosis following UV radiation.
  • To elucidate the mechanism by which MIHA inhibits apoptosis.
  • To determine the effect of DIABLO on MIHA-mediated apoptosis inhibition.

Main Methods:

  • UV radiation exposure in cellular models.
  • Analysis of caspase activation (caspase 9 and caspase 3).
  • Assessment of protein-protein interactions between MIHA, DIABLO, and caspases.

Main Results:

  • MIHA inhibited caspase 9 and caspase 3 activation after UV radiation.
  • MIHA functioned downstream of cytochrome c and DIABLO release.
  • MIHA bound to processed caspases 9 and 3, preventing feedback activation.
  • DIABLO binding to MIHA disrupted its interaction with caspase 9, promoting apoptosis.

Conclusions:

  • MIHA acts as a potent apoptosis inhibitor by directly targeting activated caspases.
  • DIABLO antagonizes MIHA's antiapoptotic function by disrupting MIHA-caspase interactions.
  • This interplay between MIHA and DIABLO represents a critical control point in the apoptotic pathway.

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