title: Iron released by sodium nitroprusside contributes to heme oxygenase-1 induction via the cAMP-protein kinase A-mitogen-activated protein kinase pathway in RAW 264.7 cells.
abstract: Nitric oxide (NO) is a potent inducer of heme oxygenase (HO)-1, and NO-induced HO-1 expression is dependent on the cGMP-signaling pathway. Sodium nitroprusside (SNP) produces NO and iron. However, it is unclear whether NO is exclusively responsible for induction of HO-1 by SNP in RAW 264.7 cells. We tested our hypothesis that iron may contribute more to the SNP induction of HO-1 than does NO by comparing the HO-1 protein level and the production of NO in RAW 264.7 cells treated with SNP and S-nitroso-N-acetyl-DL-penicillamine (SNAP). Although SNP induced less NO production than SNAP, SNP induced the production of more HO-1 protein than did SNAP. Deferoxamine (DFO) decreased SNP- but not SNAP-induced HO-1 expression but did not decrease the production of NO. SNP-induced HO-1 was significantly inhibited by specific protein kinase A (PKA) inhibitors or an antagonist of cAMP but not by guanylyl cyclase inhibitors. Exogenous iron (ferric ammonium citrate or ferricyanide) and forskolin increased the level of HO-1, which was inhibited by PKA inhibitor N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H89). These results indicate that iron and cAMP, but not cGMP, play crucial roles in the induction of HO-1 in RAW 264.7 cells. Moreover, DFO and inhibitors of extracellular signal-related kinases 1/2 or c-Jun NH(2)-terminal kinase inhibited HO-1 production induced by SNP. This study illustrates that iron rather than NO from SNP contributes to HO-1 induction. Therefore, studies on the effects of SNP should consider the role of iron in some biological functions. We concluded that iron released by SNP contributes to HO-1 induction via the cAMP-PKA-mitogen-activated protein kinase pathway.
authors.affiliation: Department of Pharmacology, College of Medicine, Gyeongsang National University, 92 Chilam-dong, Jinju, South Korea.
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Irina
authors.initials: I
authors.lastname: Tsoy
authors.forename: Min Kyu
authors.initials: MK
authors.lastname: Park
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Lee
authors.forename: Jae Heun
authors.initials: JH
authors.lastname: Lee
authors.forename: Han Geuk
authors.initials: HG
authors.lastname: Seo
authors.forename: Ki Churl
authors.initials: KC
authors.lastname: Chang
mesh_terms: D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000037:antagonists & inhibitors; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D007501:Iron / Q000494:pharmacology*; D007700:Kinetics; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology*; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology
chemical_list: D020030:Nitric Oxide Donors; D009599:Nitroprusside; D026423:S-Nitroso-N-Acetylpenicillamine; D000242:Cyclic AMP; D007501:Iron; D051547:Heme Oxygenase-1; D017868:Cyclic AMP-Dependent Protein Kinases