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Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation
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Published on: March 5, 2018

Casper is a FADD- and caspase-related inducer of apoptosis

H B Shu1, D R Halpin, D V Goeddel

  • 1Tularik, Incorporated, South San Francisco, California 94080, USA.

Immunity
|June 1, 1997
PubMed

Insights

A novel protein, Casper, interacts with key apoptosis regulators like caspase-8 and FADD. Overexpression of Casper induces apoptosis, and its inhibition blocks TNF- and Fas-mediated cell death, revealing its role in these pathways.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Caspases are crucial cysteine proteases in apoptosis.
  • Caspase-8 initiates proteolytic cascades triggered by Fas ligand and tumor necrosis factor (TNF).
  • Caspase-8 activation involves recruitment to Fas and TNF receptor-1 (TNF-R1) via FADD.

Purpose of the Study:

  • To characterize a novel protein, Casper, with sequence similarity to caspase-8.
  • To investigate Casper's interactions with apoptosis-related proteins.
  • To determine Casper's role in TNF- and Fas-induced apoptosis.

Main Methods:

  • Protein characterization and sequence analysis.
  • Co-immunoprecipitation assays to study protein interactions.
  • Overexpression studies in mammalian cells to assess apoptosis induction.
  • Analysis of deletion mutants to elucidate functional domains.

Main Results:

  • A novel 55 kDa protein, Casper, was identified with sequence similarity to caspase-8 but lacking essential caspase residues.
  • Casper interacts with FADD, caspase-8, caspase-3, TRAF1, and TRAF2.
  • Overexpression of Casper potently induces apoptosis in mammalian cells.
  • A C-terminal deletion mutant of Casper inhibits TNF- and Fas-induced cell death.

Conclusions:

  • Casper is a novel apoptosis-regulating protein, distinct from caspases.
  • Casper plays a significant role in mediating TNF- and Fas-induced apoptotic pathways.
  • Casper's interactions with multiple signaling molecules highlight its central role in apoptosis.

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