Nitric oxide mediates dendritic cell apoptosis by downregulating inhibitors of apoptosis proteins and upregulating effector caspase activity

Ala Stanford, Yue Chen, Xiao Ru Zhang, Rosemary Hoffman, Ruben Zamora, Henri R. Ford

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23 Scopus citations


Background. Dendritic cells (DCs) play a crucial role in the amplification of the immune response by promoting antigen presentation, T-lymphocyte proliferation, and proinflammatory cytokine and nitric oxide (NO) production. We have previously shown that the exogenous NO donor, s-nitroso-N-acetyl-penicillamine, promotes DC apoptosis by disrupting the mitochondrial membrane potential, which induces cytochrome-C release and activates caspase 3. To further elucidate the signaling pathway, we examined the expression of cellular inhibitors of apoptosis proteins (cIAPs) and poly (ADP-ribose) polymerase cleavage (PARP), a terminal event in the apoptotic cascade. Methods. DC2.4 were exposed to 250 μmol/L s-nitroso-N-acetyl-penicillamine for various intervals. Apoptosis and necrosis were measured by terminal deoxynucleotidyl transferase nick-end labeling assay or flow cytometry with Annexin V and propidium iodide. DC2.4 were cultured with the pan-caspase inhibitor, ZVAD (100 μmol/L). cIAP, pro-caspases, and PARP expression or activation was measured by Western blot. Caspase enzyme activity was confirmed with the use of specific substrates. Results. NO-induced DC apoptosis correlated with the downregulation of cIAP expression. Caspase 3 and 6 were upregulated by SNAP and significantly inhibited by ZVAD. Maximal PARP cleavage occurred at 8 hours and coincided with the downregulation of cIAP and peak caspase 3 and near maximal caspase 6 activity. Conclusions. NO-induced DC apoptosis is associated with the downregulation of cIAP expression, which facilitates caspase cascade activation and subsequent PARP cleavage.

Original languageEnglish (US)
Pages (from-to)326-332
Number of pages7
Issue number2
StatePublished - Jan 1 2001
Externally publishedYes


ASJC Scopus subject areas

  • Surgery

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