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Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation
08:47

Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation

Published on: March 5, 2018

Molecular determinants involved in activation of caspase 7

Dave Boucher1, Véronique Blais, Marcin Drag

  • 1Department of Pharmacology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.

Bioscience Reports
|October 15, 2010
PubMed

Insights

Initiator caspases activate executioner caspases like caspase 7 through cleavage sites on the interdomain connector (IDC). Optimizing these sites significantly enhances caspase 7 activation, revealing critical structural roles in apoptosis.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • Apoptosis involves initiator caspases activating executioner caspases via cleavage of the interdomain connector (IDC).
  • Caspase 7 activation by initiator caspases (8 and 9) relies on specific cleavage sites within its IDC.

Purpose of the Study:

  • To investigate the efficiency of caspase 7 activation sites (site 1 and site 2) by initiator caspases.
  • To elucidate the role of the IDC's primary structure and length in caspase 7 activation and activity.

Main Methods:

  • In vitro studies using recombinant proteins and activation kinetics.
  • Site-directed mutagenesis to alter caspase 7 activation motifs and IDC length.
  • Analysis of caspase 7 activation efficiency and proteolytic activity.

Main Results:

  • Caspase 7 activation sites are suboptimal for initiator caspases 8 and 9, with motif optimization yielding up to 36-fold improvement.
  • Cleavage at site 1 is preferred over site 2 due to its IDC location; swapping sites did not enhance activation.
  • Ile195 in site 1 is crucial for maintaining enzyme conformation.
  • IDC length is vital for requiring proteolysis for activation; shortening initiator caspase 8's IDC conferred this requirement.

Conclusions:

  • The primary structure of caspase 7's IDC is critical for its efficient activation and proteolytic function.
  • Specific cleavage site motifs and IDC structural integrity are key determinants of caspase activation pathways in apoptosis.

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