Differences in the Regulation of Iron Regulatory Protein-1 (IRP-1) by Extra- and Intracellular Oxidative Stress

摘要: We have studied the responses of iron regulatory protein-1 (IRP-1) to extra- and intracellular sources reactive oxygen intermediates (ROIs). IRP-1 is a cytoplasmic RNA-binding protein that regulates metabolism following its activation by deficiency, nitric oxide, administration H2O2 or antimycin A, an inhibitor respiratory chain (Hentze, M. W., Kuhn, L. C. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 8175-8182). show 10 microM suffice for complete within 60 min when generated extracellularly at steady-state. By contrast, rapid cellular degradation necessitates 5-10-fold higher bolus dose. To study oxidative stress, mitochondrial respiration was inhibited with A (to generate stress leakage ROIs from complex III), catalase blocked 3-amino-1,2,4-triazole diminish degradation); in parallel, 2',7'-dichlorodihydrofluorescein diacetate used as redox-sensitive probe monitor levels fluorescence-activated cell sorting. Catalase inhibition elevates H2O2, but surprisingly does not cause concomitant activation. Following treatment, activated, kinetics lag behind increase detectable H2O2. thus activated both generation ROIs. While extracellular rapidly activates even without increases elevation sufficient represents novel example H2O2-regulated responds differentially alterations levels. Our data also suggest direct attack on 4Fe-4S cluster (or H2O2-derived species) unlikely explanation stress.