Inactivation of multiple targets by nitric oxide in CD95-triggered apoptosis.
Nitric oxide (NO) plays an important anti-apoptotic role by inactivating both upstream and downstream apoptotic molecules. We now report that exogenously supplied NO protected Jurkat T cells from anti-CD95-stimulated apoptosis. We have recently shown that nitrosation of the activator protein-1 (AP-1) transcriptional factor is crucial for NO-mediated inhibition of cell death triggered by etoposide or ceramide. Since the inhibition of apoptosis by NO has been reported to involve AP-1, we evaluated its involvement in in CD95-mediated cell death. Cross-linking of CD95 enhanced AP-1 DNA binding activity and AP-1-dependent CD95L transactivation, which were both significantly reduced by different NO-donors compounds. However, AP-1 induction does not seem to significantly contribute to anti-CD95-triggered apoptosis, as cell death could not be prevented by using the recombinant Fas-Fc fusion protein which inhibits the CD95/CD95L interaction. We observed that caspase 3-like activity was negatively modulated by several NO-donors in vitro and that titratable thiol groups of purified caspases 3, 7, and 9 decreased in the presence of NO-releasing compounds. In conclusion, we demonstrated that NO-mediated inhibition of other targets, possibly caspases, but not AP-1, is a crucial event responsible for protection against anti-CD95-stimulated apoptosis. Even though NO affects multiple molecular mechanisms, the relevant target for exerting the cellular effects, may vary among different models.
Bernassola
F
F
Biochemistry Laboratory, IDI-IRCCS, c/o Department of Experimental Medicine, University of Rome Tor Vergata, 00133 Rome, Italy.
Catani
M V
MV
Corazzari
M
M
Rossi
A
A
Melino
G
G
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D020169:Caspases / Q000187:drug effects* / Q000378:metabolism; D053222:Fas Ligand Protein; D006801:Humans; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000187:drug effects* / Q000378:metabolism; D019014:fas Receptor / Q000737:chemistry / Q000378:metabolism
C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D018808:Transcription Factor AP-1; D019014:fas Receptor; D009569:Nitric Oxide; D020169:Caspases