title: Roles for cytosolic NADPH redox in regulating pulmonary artery relaxation by thiol oxidation-elicited subunit dimerization of protein kinase G1α.
abstract: The activity of glucose-6-phosphate dehydrogenase (G6PD) appears to control a vascular smooth muscle relaxing mechanism regulated through cytosolic NADPH oxidation. Since our recent studies suggest that thiol oxidation-elicited dimerization of the 1α form of protein kinase G (PKG1α) contributes to the relaxation of isolated endothelium-removed bovine pulmonary arteries (BPA) to peroxide and responses to hypoxia, we investigated whether cytosolic NADPH oxidation promoted relaxation by PKG1α dimerization. Relaxation of BPA to G6PD inhibitors 6-aminonicotinamide (6-AN) and epiandrosterone (studied under hypoxia to minimize basal levels of NADPH oxidation and PKG1α dimerization) was associated with increased PKG1α dimerization and PKG-mediated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. Depletion of PKG1α by small inhibitory RNA (siRNA) inhibited relaxation of BPA to 6-AN and attenuated the increase in VASP phosphorylation. Relaxation to 6-AN did not appear to be altered by depletion of soluble guanylate cyclase (sGC). Depletion of G6PD, thioredoxin-1 (Trx-1), and Trx reductase-1 (TrxR-1) in BPA with siRNA increased PKG1α dimerization and VASP phosphorylation and inhibited force generation under aerobic and hypoxic conditions. Depletion of TrxR-1 with siRNA inhibited the effects of 6-AN and enhanced similar responses to peroxide. Peroxiredoxin-1 depletion by siRNA inhibited PKG dimerization to peroxide, but it did not alter PKG dimerization under hypoxia or the stimulation of dimerization by 6-AN. Thus regulation of cytosolic NADPH redox by G6PD appears to control PKG1α dimerization in BPA through its influence on Trx-1 redox regulation by the NADPH dependence of TrxR-1. NADPH regulation of PKG dimerization may contribute to vascular responses to hypoxia that are associated with changes in NADPH redox.
authors.affiliation: Department of Physiology, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Boon Hwa
authors.initials: BH
authors.lastname: Neo
authors.forename: Dhara
authors.initials: D
authors.lastname: Patel
authors.forename: Sharath
authors.initials: S
authors.lastname: Kandhi
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wolin
mesh_terms: D000818:Animals; D002417:Cattle; D015815:Cell Adhesion Molecules / Q000378:metabolism; D015687:Cell Hypoxia; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism*; D009940:Organoids; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D055503:Protein Multimerization; D021122:Protein Subunits; D011651:Pulmonary Artery / Q000201:enzymology*; D034622:RNA Interference; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D015398:Signal Transduction; D000071756:Soluble Guanylyl Cyclase; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D054481:Thioredoxin Reductase 1 / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism; D046509:Tissue Culture Techniques; D014162:Transfection; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D008840:Microfilament Proteins; D010750:Phosphoproteins; D021122:Protein Subunits; D018160:Receptors, Cytoplasmic and Nuclear; D013438:Sulfhydryl Compounds; D014665:Vasodilator Agents; D000098662:Vasodilator-Stimulated Phosphoprotein; D013879:Thioredoxins; D005954:Glucosephosphate Dehydrogenase; D054464:Peroxiredoxins; D019255:NADPH Oxidases; D054481:Thioredoxin Reductase 1; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase
keywords: glucose-6-phosphate dehydrogenase; hypoxia; thioredoxin