Activation of the cell death program by nitric oxide involves inhibition of the proteasome.
The ubiquitin/proteasome pathway mediates the degradation of many short-lived proteins that are critically involved in the regulation of cell proliferation and cell death, including the tumor suppressor protein p53. Accumulation of p53 and induction of apoptosis in RAW 264.7 macrophages in response to nitric oxide are well established. However, the molecular mechanisms involved in nitric oxide-induced p53 accumulation are unknown. Here we show that, similar to nitric oxide, treatment of macrophages with specific proteasome inhibitors, including clastolactacystin-beta-lactone, induces p53 accumulation and apoptosis, suggesting that nitric oxide may affect the activity of the proteasome. In support of this hypothesis, both exposure of cells to S-nitrosoglutathione and stimulation of endogenous nitric oxide production by lipopolysaccharide/interferon-gamma treatment result in inhibition of proteasome activity as measured in vitro by the degradation of the proteasome-specific substrate succinyl-Leu-Leu-Val-Tyr-4-methylcoumarin-7-amide. Moreover, chemically diverse nitric oxide donors interfere with proteasome-mediated degradation of polyubiquitinated p53 in vitro. These data imply that nitric oxide-induced apoptosis and accumulation of p53 are, at least in part, mediated by inhibition of the proteasome.
Faculty of Medicine, Department of Medicine IV-Experimental Division, University of Erlangen-Nürnberg, Loschgestrasse 8, 91054 Erlangen, Germany.
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Glockzin
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von Knethen
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Scheffner
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Brüne
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D003374:Coumarins / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000187:drug effects* / Q000378:metabolism; D053938:DNA Fragmentation; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D009097:Multienzyme Complexes / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000494:pharmacology; D009842:Oligopeptides / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D026422:S-Nitrosoglutathione; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism
D003374:Coumarins; D009097:Multienzyme Complexes; D009603:Nitroso Compounds; D009842:Oligopeptides; D011480:Protease Inhibitors; D016159:Tumor Suppressor Protein p53; D014452:Ubiquitins; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; C046582:succinyl-leucyl-leucyl-valyl-tyrosyl-methylcoumarinamide; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D005978:Glutathione