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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

Caspase-1 promiscuity is counterbalanced by rapid inactivation of processed enzyme

John G Walsh1, Susan E Logue, Alexander U Lüthi

  • 1Molecular Cell Biology Laboratory, Department of Genetics, The Smurfit Institute, Trinity College, Dublin 2, Ireland.

The Journal of Biological Chemistry
|July 16, 2011
PubMed

Insights

Caspase-1, crucial for inflammation, shows broad substrate activity but is rapidly inactivated. This instability, not specificity, likely explains its limited known substrates, unlike stable caspases-3 and -7.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • Caspases are cysteine proteases regulating apoptosis and inflammation.
  • Apoptosis effector caspases (caspase-3, -7) have many substrates, while inflammatory caspase-1 has few known substrates.
  • The reason for caspase-1's limited substrate identification is unclear.

Purpose of the Study:

  • To compare the substrate specificity of inflammatory caspase-1 with apoptotic caspases (-3, -7).
  • To investigate whether substrate specificity differences or protein stability explain caspase-1's limited substrate repertoire.

Main Methods:

  • Compared substrate specificity of caspases-1, -3, and -7 using peptide and protein substrates.
  • Measured endogenous concentrations of caspases.
  • Determined the half-lives of active caspase-1, -3, and -7.

Main Results:

  • Caspase-1 exhibited concentration-dependent promiscuity towards various substrates.
  • Endogenous concentrations of caspase-1 and caspase-3 were similar.
  • Active caspase-1 was rapidly degraded (half-life ~9 min) compared to caspase-3 (~8 h) and caspase-7 (~11 h).

Conclusions:

  • Caspase-1's substrate specificity is maintained by its rapid inactivation, not inherent specificity.
  • The lability of processed caspase-1 limits its activity and substrate interactions in vivo.
  • This contrasts with the stability and broad substrate interactions of effector caspases.

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