Journal
BIOCHEMICAL PHARMACOLOGY
Volume 75, Issue 11, Pages 2234-2244Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.bcp.2008.02.026
Keywords
glutathionylation; glutathione; caspase; thionylation; oxidative stress; apoptosis
Categories
Funding
- NCI NIH HHS [CA68384, P01 CA068384-080003, P01 CA068384] Funding Source: Medline
- NIDCR NIH HHS [DE13222, P01 DE013222-03] Funding Source: Medline
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Protein glutathionylation is a post-translational modification that may account for a broad mechanism of redox signaling. The caspase family of cysteine proteases represents a potential target for regulation by glutathionylation. To examine this, caspase proteins, derived from HL-60 cells after activation with actinomycin D, were incubated with GSSG. Total protein glutathionylation was enhanced and caspase-3 activity was inhibited in a dose- and time-dependent manner by GSSG. Caspase inhibition was reversible by thiol-specific reducing reagents. Proteolytic activation of caspases was also affected, as the activation of procaspase-3 and procaspase-9 in HL-60 cell extracts induced by cytochrome c and dATP was inhibited by pre-incubation with GSSG. When biotin-labeled GSSG was incubated with recombinant caspase-3, biotin label was found associated with both p12 and p17 subunits of active caspase-3 by non-reducing SDS-PAGE. Caspase-3 glutathionylation was confirmed by matrix assisted laser desorption ionization (MALDI) mass spectrometric analysis of GSSG-treated recombinant caspase-3. Specific sites of glutathionylation were identified as Cys(135) of the p17 protein (the active site) and Cys(45) of the p12 protein. These results indicate that glutathionylation of caspase can occur at physiologically relevant concentrations of GSSG and results in the inhibition of caspase activation and activity. (C) 2008 Elsevier Inc. All rights reserved.
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