Hsp60 accelerates the maturation of pro-caspase-3 by upstream activator proteases during apoptosis

EMBO J. 1999 Apr 15;18(8):2049-56. doi: 10.1093/emboj/18.8.2049.

Abstract

The activation of caspases represents a critical step in the pathways leading to the biochemical and morphological changes that underlie apoptosis. Multiple pathways leading to caspase activation appear to exist and vary depending on the death-inducing stimulus. We demonstrate that the activation of caspase-3, in Jurkat cells stimulated to undergo apoptosis by a Fas-independent pathway, is catalyzed by caspase-6. Caspase-6 was found to co-purify with caspase-3 as part of a multiprotein activation complex from extracts of camptothecin-treated Jurkat cells. A biochemical analysis of the protein constituents of the activation complex showed that Hsp60 was also present. Furthermore, an interaction between Hsp60 and caspase-3 could be demonstrated by co-immunoprecipitation experiments using HeLa as well as Jurkat cell extracts. Using a reconstituted in vitro system, Hsp60 was able to substantially accelerate the maturation of procaspase-3 by different upstream activator caspases and this effect was dependent on ATP hydrolysis. We propose that the ATP-dependent 'foldase' activity of Hsp60 improves the vulnerability of pro-caspase-3 to proteolytic maturation by upstream caspases and that this represents an important regulatory event in apoptotic cell death.

MeSH terms

  • Amino Acid Sequence
  • Apoptosis*
  • Caspase 3
  • Caspases / isolation & purification
  • Caspases / metabolism*
  • Chaperonin 60 / metabolism*
  • Chromatography, Ion Exchange
  • Enzyme Activation
  • Enzyme Precursors / isolation & purification
  • Enzyme Precursors / metabolism*
  • HeLa Cells
  • Humans
  • Jurkat Cells
  • Molecular Sequence Data
  • Protein Processing, Post-Translational
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Spectrophotometry, Ultraviolet

Substances

  • Chaperonin 60
  • Enzyme Precursors
  • Recombinant Proteins
  • CASP3 protein, human
  • Caspase 3
  • Caspases