[HTML][HTML] Hsp60 accelerates the maturation of pro‐caspase‐3 by upstream activator proteases during apoptosis

S Xanthoudakis, S Roy, D Rasper, T Hennessey… - The EMBO …, 1999 - embopress.org
S Xanthoudakis, S Roy, D Rasper, T Hennessey, Y Aubin, R Cassady, P Tawa, R Ruel…
The EMBO journal, 1999embopress.org
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 …
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.
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