TY - JOUR T1 - 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 JF - Molecular Pharmacology JO - Mol Pharmacol SP - 1633 LP - 1640 DO - 10.1124/mol.105.020487 VL - 69 IS - 5 AU - Hye Jung Kim AU - Irina Tsoy AU - Min Kyu Park AU - Young Soo Lee AU - Jae Heun Lee AU - Han Geuk Seo AU - Ki Churl Chang Y1 - 2006/05/01 UR - http://molpharm.aspetjournals.org/content/69/5/1633.abstract N2 - 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 NH2-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. ER -