Coexpression of GTP cyclohydrolase I and inducible nitric oxide synthase mRNAs in mouse osteoblastic cells activated by proinflammatory cytokines.
Proinflammatory cytokines, a combination of IL-1beta, TNF-alpha, and IFN-gamma, caused mRNA expression of GTP cyclohydrolase I (GTP-CH), the rate-limiting enzyme in tetrahydrobiopterin (BH4) biosynthesis, and of inducible nitric oxide synthase (iNOS) in a well-characterized osteoblastic clone MC3T3-E1 cell line. We found the expression of the GTP-CH gene in osteoblasts for the first time. The expression of GTP-CH and iNOS mRNAs was found to be maximal at 3 and 9 h, respectively. The expression of both genes elicited increases in BH4 and NO levels. Pharmacological studies using 2,4-diamino-6-hydroxypyrimidine, an inhibitor of GTP-CH activity, showed that BH4 is involved in the activity of iNOS, but not in the induction of iNOS mRNA. The results using an inhibitor of nuclear factor (NF)-kappaB and activating protein-1 (AP-1) activation suggested that coinduction of the two genes in response to cytokines occurred via activation of NF-kappaB and AP-1. In MC3T3-E1 cells BH4 and sepiapterin, producing BH4, could protect against apoptosis, i.e. the degradation of nuclear DNA in the cells, induced by NO derived from S-nitroso-N-acetyl-D-L-penicillamine. These results suggest that the induction of BH4 together with NO by proinflammatory cytokines could protect against NO-induced apoptosis in MC3T3-E1 cells.
Togari
A
A
Department of Pharmacology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan. togariaf@dpc.aichi-gakuin.ac.jp
Arai
M
M
Mogi
M
M
Kondo
A
A
Nagatsu
T
T
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology*; D053938:DNA Fragmentation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006136:GTP Cyclohydrolase / Q000096:biosynthesis*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007042:Hypoxanthines / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II; D010006:Osteoblasts / Q000201:enzymology*; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D011392:Proline / Q000031:analogs & derivatives / Q000494:pharmacology; D011621:Pteridines / Q000494:pharmacology; D011622:Pterins; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis; D026423:S-Nitroso-N-Acetylpenicillamine; D013859:Thiocarbamates / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016207:Cytokines; D004791:Enzyme Inhibitors; D007042:Hypoxanthines; D007375:Interleukin-1; D016328:NF-kappa B; D011621:Pteridines; D011622:Pterins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013859:Thiocarbamates; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; C066229:prolinedithiocarbamate; D001708:Biopterins; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D007371:Interferon-gamma; D011392:Proline; C016727:sepiapterin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D006136:GTP Cyclohydrolase; C017202:2,4-diaminohypoxanthine; C003402:sapropterin; D010396:Penicillamine; D003474:Curcumin