Nitrosothiol Formation and Protection against Fenton Chemistry by Nitric Oxide-induced Dinitrosyliron Complex Formation from Anoxia-initiated Cellular Chelatable Iron Increase

• Published in: The Journal of biological chemistry Vol. 289; no. 29; pp. 19917 - 19927
• Main Authors: Li, Qian, Li, Chuanyu, Mahtani, Harry K., Du, Jian, Patel, Aashka R., Lancaster, Jack R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.07.2014; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Cell Hypoxia - physiology; Cell Line; Chelatable Iron; Deferoxamine - pharmacology; Dinitrosyliron Complexes; Electron Paramagnetic Resonance (EPR); Electron Spin Resonance Spectroscopy; Fenton Reaction; Hydrogen Peroxide - metabolism; Hypoxia; Iron; Iron - metabolism; Iron Chelating Agents - pharmacology; Macrophages - drug effects; Macrophages - metabolism; Mice; Molecular Biophysics; Nitric Oxide; Nitric Oxide - metabolism; Nitrogen Oxides - metabolism; Nitrosothiol; Reactive Oxygen Species (ROS); Reactive Oxygen Species - metabolism; S-Nitrosothiols - metabolism; Thiol; Thiol; Dinitrosyliron Complexes; Reactive Oxygen Species (ROS); Fenton Reaction; Electron Paramagnetic Resonance (EPR); Chelatable Iron; Hypoxia; Iron; Nitrosothiol; Nitric Oxide
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.569764

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with •NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged •NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief •NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1–2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief •NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of •NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of •NO. Background: Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings. Results: Cellular DNIC formation upon brief nitric oxide (•NO) exposure is dramatically increased by anoxia pretreatment. Conclusion: DNIC is rapidly generated from •NO reaction with chelatable iron. Significance: This experimental system provides a useful tool to manipulate the levels of DNIC and probe their cellular functions.