Induction of CHOP and apoptosis by nitric oxide in p53-deficient microglial cells.
Excessive nitric oxide (NO) has been implicated in neurotoxicity after stresses such as ischemia. NO toxicity is generally thought to be mediated by the DNA damage-p53 pathway or mitochondrial dysfunction. We investigated the mechanism of NO toxicity by using murine microglial MG5 cells established from p53-deficient mice. When MG5 cells were exposed to bacterial lipopolysaccharide plus interferon-gamma, mRNA and protein for inducible NO synthase (iNOS) were markedly induced, and apoptosis occurred. Under these conditions, we found that mRNA and protein for CHOP/GADD153, a C/EBP family transcription factor which is involved in endoplasmic reticulum (ER) stress-induced apoptosis, are induced. iNOS mRNA was induced 2 h after treatment, whereas CHOP mRNA began to increase at 6 h with a time lag. CHOP mRNA was also induced by NO donors S-nitroso-N-acetyl-DL-penicillamine (SNAP) or NOC18, or a peroxynitrite generator 3-(4-morpholinyl)-sydnonimine hydrochloride (SIN-1). Bip/GRP78, an ER chaperone which is known to be induced by ER stress, was also induced by SNAP or SIN-1, indicating that NO causes ER stress. These results suggest that NO-induced apoptosis in MG5 cells occurs through the ER stress pathway involving CHOP, but is independent of p53.
Kawahara
K
K
Department of Molecular Genetics, Kumamoto University School of Medicine, Honjo, Japan.
Oyadomari
S
S
Gotoh
T
T
Kohsaka
S
S
Nakayama
H
H
Mori
M
M
D000818:Animals; D017209:Apoptosis; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D000091342:Endoplasmic Reticulum Chaperone BiP; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000378:metabolism
D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; C497250:Ddit3 protein, mouse; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D008070:Lipopolysaccharides; D018832:Molecular Chaperones; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D051742:Transcription Factor CHOP; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse