Regulated protein denitrosylation by cytosolic and mitochondrial thioredoxins.
Nitric oxide acts substantially in cellular signal transduction through stimulus-coupled S-nitrosylation of cysteine residues. The mechanisms that might subserve protein denitrosylation in cellular signaling remain uncharacterized. Our search for denitrosylase activities focused on caspase-3, an exemplar of stimulus-dependent denitrosylation, and identified thioredoxin and thioredoxin reductase in a biochemical screen. In resting human lymphocytes, thioredoxin-1 actively denitrosylated cytosolic caspase-3 and thereby maintained a low steady-state amount of S-nitrosylation. Upon stimulation of Fas, thioredoxin-2 mediated denitrosylation of mitochondria-associated caspase-3, a process required for caspase-3 activation, and promoted apoptosis. Inhibition of thioredoxin-thioredoxin reductases enabled identification of additional substrates subject to endogenous S-nitrosylation. Thus, specific enzymatic mechanisms may regulate basal and stimulus-induced denitrosylation in mammalian cells.
Benhar
Moran
M
Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
Forrester
Michael T
MT
Hess
Douglas T
DT
Stamler
Jonathan S
JS
D000818:Animals; D017209:Apoptosis; D001310:Auranofin / Q000494:pharmacology; D001665:Binding Sites; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D008264:Macrophages / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D026403:S-Nitrosothiols / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism
D061945:Caspase Inhibitors; D004137:Dinitrochlorobenzene; D024101:Mitochondrial Proteins; D011994:Recombinant Proteins; D026403:S-Nitrosothiols; C491203:TXN protein, human; C467002:TXN2 protein, human; D019014:fas Receptor; D009569:Nitric Oxide; D001310:Auranofin; D013879:Thioredoxins; D013880:Thioredoxin-Disulfide Reductase; D053148:Caspase 3