Hsp60 accelerates the maturation of pro-caspase-3 by upstream activator proteases during apoptosis.
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.
Xanthoudakis
S
S
Department of Biochemistry and Molecular Biology, Merck Frosst Centre for Therapeutic Research, Kirkland, Quebec, Canada H9H 3L1. steven_xanthoudakis@merck.com
Roy
S
S
Rasper
D
D
Hennessey
T
T
Aubin
Y
Y
Cassady
R
R
Tawa
P
P
Ruel
R
R
Rosen
A
A
Nicholson
D W
DW
D000595:Amino Acid Sequence; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000302:isolation & purification / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
D018834:Chaperonin 60; D004792:Enzyme Precursors; D011994:Recombinant Proteins; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases