curcumin and sepiapterin

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.

Topics: 3T3 Cells; Animals; Apoptosis; Biopterins; Cell Nucleus; Cell Survival; Curcumin; Cytokines; DNA Fragmentation; Enzyme Inhibitors; Gene Expression Regulation, Enzymologic; GTP Cyclohydrolase; Hypoxanthines; Interferon-gamma; Interleukin-1; Kinetics; Mice; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Osteoblasts; Penicillamine; Proline; Pteridines; Pterins; Recombinant Proteins; RNA, Messenger; S-Nitroso-N-Acetylpenicillamine; Thiocarbamates; Transcription Factor AP-1; Transcription, Genetic; Transfection; Tumor Necrosis Factor-alpha