title: NAD(P)H-dependent quinone oxidoreductase 1 (NQO1) and cytochrome P450 oxidoreductase (CYP450OR) differentially regulate menadione-mediated alterations in redox status, survival and metabolism in pancreatic β-cells.
abstract: NQO1 (NAD(P)H-quinone oxidoreductase 1) reduces quinones and xenobiotics to less-reactive compounds via 2-electron reduction, one feature responsible for the role of NQO1 in antioxidant defense in several tissues. In contrast, NADPH cytochrome P450 oxidoreductase (CYP450OR), catalyzes the 1-electron reduction of quinones and xenobiotics, resulting in enhanced superoxide formation. However, to date, the roles of NQO1 and CYP450OR in pancreatic β-cell metabolism under basal conditions and oxidant challenge have not been characterized. Using NQO1 inhibition, over-expression and knock out, we have demonstrated that, in addition to protection of β-cells from toxic concentrations of the redox cycling quinone menadione, NQO1 also regulates the basal level of reduced-to-oxidized nucleotides, suggesting other role(s) beside that of an antioxidant enzyme. In contrast, over-expression of NADPH cytochrome P450 oxidoreductase (CYP450OR) resulted in enhanced redox cycling activity and decreased cellular viability, consistent with the enhanced generation of superoxide and H2O2. Basal expression of NQO1 and CYP450OR was comparable in isolated islets and liver. However, NQO1, but not CYP450OR, was strongly induced in β-cells exposed to menadione. NQO1 and CYP450OR exhibited a reciprocal preference for reducing equivalents in β-cells: while CYP450OR preferentially utilized NADPH, NQO1 primarily utilized NADH. Together, these results demonstrate that NQO1 and CYP450OR reciprocally regulate oxidant metabolism in pancreatic β-cells.
authors: Department of Science, United States Coast Guard Academy, New London, CT 06320, United States; Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, United States; Department of Molecular Pharmacology and Physiology, University of South Florida, FL 33612, United States.
authors: Joshua P
authors: JP
authors: Gray
authors: Department of Molecular Pharmacology and Physiology, University of South Florida, FL 33612, United States.
authors: Shpetim
authors: S
authors: Karandrea
authors: University of Puerto Rico at Cayey, Puerto Rico.
authors: Delaine Zayasbazan
authors: DZ
authors: Burgos
authors: Department of Pharmacology and Experimental Therapeutics, University of Maryland, MD 20742, United States.
authors: Anil A
authors: AA
authors: Jaiswal
authors: Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543, United States; Department of Molecular Pharmacology and Physiology, University of South Florida, FL 33612, United States. Electronic address: eheart@health.usf.edu.
authors: Emma A
authors: EA
authors: Heart
mesh_terms: D002460:Cell Line; D002470:Cell Survival; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D055879:Gene Knock-In Techniques; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D024483:Vitamin K 3 / Q000378:metabolism / Q000494:pharmacology*; D014815:Vitamins / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D014815:Vitamins; D024483:Vitamin K 3; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human
keywords: CYP450OR; Menadione; NAD(P)H; NQO1; Pancreatic β-cell; Redox cycling