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: Boon Hwa Neo, Dhara Patel, Sharath Kandhi, Michael S Wolin
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 305 Issue 3 Pg. H330-43 (Aug 01 2013) ISSN: 1522-1539 [Electronic] United States
• PMID: 23709600 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Cell Adhesion Molecules
• Enzyme Inhibitors
• Microfilament Proteins
• Phosphoproteins
• Protein Subunits
• Receptors, Cytoplasmic and Nuclear
• Sulfhydryl Compounds
• Vasodilator Agents
• vasodilator-stimulated phosphoprotein
• Thioredoxins
• Glucosephosphate Dehydrogenase
• Peroxiredoxins
• NADPH Oxidases
• Thioredoxin Reductase 1
• Cyclic GMP-Dependent Protein Kinase Type I
• Guanylate Cyclase
• Soluble Guanylyl Cyclase

Topics

• Animals
• Cattle
• Cell Adhesion Molecules (metabolism)
• Cell Hypoxia
• Cyclic GMP-Dependent Protein Kinase Type I (genetics, metabolism)
• Cytosol (enzymology)
• Enzyme Activation
• Enzyme Inhibitors (pharmacology)
• Glucosephosphate Dehydrogenase (antagonists & inhibitors, metabolism)
• Guanylate Cyclase (metabolism)
• Microfilament Proteins (metabolism)
• NADPH Oxidases (metabolism)
• Organoids
• Oxidation-Reduction
• Peroxiredoxins (metabolism)
• Phosphoproteins (metabolism)
• Phosphorylation
• Protein Multimerization
• Protein Subunits
• Pulmonary Artery (enzymology)
• RNA Interference
• Receptors, Cytoplasmic and Nuclear (metabolism)
• Signal Transduction
• Soluble Guanylyl Cyclase
• Sulfhydryl Compounds (metabolism)
• Thioredoxin Reductase 1 (metabolism)
• Thioredoxins (metabolism)
• Tissue Culture Techniques
• Transfection
• Vasodilation
• Vasodilator Agents (pharmacology)