scholarly journals Roles for Decreased Peroxide‐Mediated Relaxation by Both Soluble Guanylate Cyclase and Thiol oxidation‐Elicited Subunit Dimerization Activation of Protein Kinase G in the Contraction of Pulmonary Arteries to Hypoxia

2011 ◽  
Vol 25 (S1) ◽  
Author(s):  
Boon Hwa Neo ◽  
Sharath Kandhi ◽  
Michael Wolin
Keyword(s):  
Protein Kinase ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Arteries ◽  
Protein Kinase G ◽  
Thiol Oxidation

scholarly journals Roles for soluble guanylate cyclase and a thiol oxidation-elicited subunit dimerization of protein kinase G in pulmonary artery relaxation to hydrogen peroxide

2010 ◽  
Vol 299 (4) ◽  
pp. H1235-H1241 ◽  
Author(s):  
Boon Hwa Neo ◽  
Sharath Kandhi ◽  
Michael S. Wolin
Keyword(s):  
Nitric Oxide ◽  
Hydrogen Peroxide ◽  
Protein Kinase ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Arteries ◽  
Protein Kinase G ◽  
Thiol Oxidation ◽  
Organoid Culture ◽  
Vasp Phosphorylation

We have previously provided evidence that hydrogen peroxide (H2O2) stimulates soluble guanylate cyclase (sGC) under conditions where it relaxes isolated endothelium-removed bovine pulmonary arteries (BPAs). Since it was recently reported that H2O2 induces coronary vasorelaxation associated with a nitric oxide/cGMP-independent thiol oxidation/subunit dimerization-elicited activation of protein kinase G (PKG), we investigated whether this mechanism participates in the relaxation of BPAs to H2O2. BPAs precontracted with serotonin (incubated under hypoxia to lower endogenous H2O2) were exposed to increasing concentrations of H2O2. It was observed that 0.1–1 mM H2O2 caused increased PKG dimerization and relaxation. These responses were associated with increased phosphorylation of vasodilator-stimulated phosphoprotein (VASP) at the serine-239 site known to be mediated by PKG. Treatment of BPAs with 1 mM DTT attenuated PKG dimerization, VASP phosphorylation, and relaxation to H2O2. An organoid culture of BPAs for 48 h with 10 μM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a heme oxidant inhibitor of sGC activation, depleted sGC expression by 85%, associated with a 67% attenuation of VASP phosphorylation and 48% inhibition of relaxation elicited by 100 μM H2O2. Thus both a sGC activation/cGMP-dependent and a thiol oxidation subunit dimerization/cGMP-independent activation of PKG appear to contribute to the relaxation of BPAs elicited by H2O2.

scholarly journals Roles for cytosolic NADPH redox in regulating pulmonary artery relaxation by thiol oxidation-elicited subunit dimerization of protein kinase G1α

2013 ◽  
Vol 305 (3) ◽  
pp. H330-H343 ◽  
Author(s):  
Boon Hwa Neo ◽  
Dhara Patel ◽  
Sharath Kandhi ◽  
Michael S. Wolin
Keyword(s):  
Protein Kinase ◽  
Redox Regulation ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Arteries ◽  
Thiol Oxidation ◽  
Hypoxic Conditions ◽  
Vasp Phosphorylation ◽  
Thioredoxin 1 ◽  
Nadph Oxidation ◽  
Glucose 6 Phosphate Dehydrogenase

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.

scholarly journals Soluble Guanylate Cyclase as a Novel Treatment Target for Osteoporosis

Endocrinology ◽  
2014 ◽  
Vol 155 (12) ◽  
pp. 4720-4730 ◽  
Author(s):  
Jisha Joshua ◽  
Gerburg K. Schwaerzer ◽  
Hema Kalyanaraman ◽  
Esther Cory ◽  
Robert L. Sah ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Protein Kinase ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Bone Microarchitecture ◽  
Protein Kinase G ◽  
Protective Effects ◽  
Major Health Problem ◽  
Ovariectomized Mice ◽  
17Β Estradiol

Osteoporosis is a major health problem leading to fractures that cause substantial morbidity and mortality. Current osteoporosis therapies have significant drawbacks, creating a need for novel bone-anabolic agents. We previously showed that the nitric oxide/cyclic GMP (cGMP)/protein kinase G pathway mediates some of the anabolic effects of estrogens and mechanical stimulation in osteoblasts and osteocytes, leading us to hypothesize that cGMP-elevating agents may have bone-protective effects. We tested cinaciguat, a prototype of a novel class of soluble guanylate cyclase activators, in a mouse model of estrogen deficiency-induced osteoporosis. Compared with sham-operated mice, ovariectomized mice had lower serum cGMP concentrations, which were largely restored to normal by treatment with cinaciguat or low-dose 17β-estradiol. Microcomputed tomography of tibiae showed that cinaciguat significantly improved trabecular bone microarchitecture in ovariectomized animals, with effect sizes similar to those obtained with estrogen replacement therapy. Cinaciguat reversed ovariectomy-induced osteocyte apoptosis as efficiently as estradiol and enhanced bone formation parameters in vivo, consistent with in vitro effects on osteoblast proliferation, differentiation, and survival. Compared with 17β-estradiol, which completely reversed the ovariectomy-induced increase in osteoclast number, cinaciguat had little effect on osteoclasts. Direct guanylate cyclase stimulators have been extremely well tolerated in clinical trials of cardiovascular diseases, and our findings provide proof-of-concept for this new class of drugs as a novel, anabolic treatment strategy for postmenopausal osteoporosis, confirming an important role of nitric oxide/cGMP/protein kinase G signaling in bone.

Regulation of NHE3 by nitric oxide in Caco-2 cells

2002 ◽  
Vol 283 (3) ◽  
pp. G747-G756 ◽  
Author(s):  
Ravinder K. Gill ◽  
Seema Saksena ◽  
Irfan Ali Syed ◽  
Sangeeta Tyagi ◽  
Waddah A. Alrefai ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Signal Transduction Pathway ◽  
Specific Protein ◽  
Protein Kinase G ◽  
Kinase A ◽  
Specific Protein Kinase

The effect of nitric oxide (NO) on Na+/H+ exchange (NHE) activity was investigated utilizing Caco-2 cells as an experimental model. Incubation of Caco-2 cells with 10−3 M S-nitroso- N-acetylpenicillamine (SNAP), a conventional donor of NO, for 20 min resulted in a ∼45% dose-dependent decrease in NHE activity, as determined by assay of ethylisopropylamiloride-sensitive 22Na uptake. A similar decrease in NHE activity was observed utilizing another NO-specific donor, sodium nitroprusside. SNAP-mediated inhibition of NHE activity was not secondary to a loss of cell viability. NHE3 activity was significantly reduced by SNAP ( P < 0.05), whereas NHE2 activity was essentially unaltered. The effects of SNAP were mediated by the cGMP-dependent signal transduction pathway as follows: 1) LY-83583 and 1 H-(1,2,4)oxadiazolo(4,3- a)quinoxalin-1-one (ODQ), specific inhibitors of soluble guanylate cyclase, blocked the inhibitory effect of SNAP on NHE; 2) 8-bromo-cGMP mimicked the effects of SNAP on NHE activity; 3) the SNAP-induced decrease in NHE activity was counteracted by a specific protein kinase G inhibitor, KT-5823 (1 μM); 4) chelerythrine chloride (2 μM) or calphostin C (200 nM), specific protein kinase C inhibitors, did not affect inhibition of NHE activity by SNAP; 5) there was no cross activation by the protein kinase A-dependent pathway, as the inhibitory effects of SNAP were not blocked by Rp-cAMPS (25 μM), a specific protein kinase A inhibitor. These data provide novel evidence that NO inhibits NHE3 activity via activation of soluble guanylate cyclase, resulting in an increase in intracellular cGMP levels and activation of protein kinase G.

scholarly journals Nitric oxide co-ordinates the activities of the capacitative and non-capacitative Ca2+-entry pathways regulated by vasopressin

2003 ◽  
Vol 370 (2) ◽  
pp. 439-448 ◽  
Author(s):  
Zahid MONEER ◽  
Jeanette L. DYER ◽  
Colin W. TAYLOR
Keyword(s):  
Arachidonic Acid ◽  
Protein Kinase ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Protein Kinase G ◽  
Acid Activation ◽  
Reciprocal Regulation ◽  
A7r5 Cells ◽  
Subsequent Activation ◽  
Stimulation Of

In A7r5 vascular smooth muscle cells vasopressin, via arachidonic acid, regulates two Ca2+-entry pathways. Capacitative Ca2+ entry (CCE), activated by empty Ca2+ stores, is inhibited by arachidonic acid, and non-capacitative Ca2+ entry (NCCE) is stimulated by it. This reciprocal regulation ensures that all Ca2+ entry is via NCCE in the presence of vasopressin, while CCE mediates a transient Ca2+ entry only after removal of vasopressin. We demonstrate that type III NO synthase (NOS III) is expressed in A7r5 cells and that NO inhibits CCE. Inhibition of CCE by vasopressin requires NOS III and the requirement lies downstream of arachidonic acid. Activation of soluble guanylate cyclase by NO and subsequent activation of protein kinase G are required for inhibition of CCE. Stimulation of NCCE by vasopressin also requires NOS III, but the stimulation is neither mimicked by cGMP nor blocked by inhibitors of soluble guanylate cyclase or protein kinase G. We conclude that arachidonic acid formed in response to vasopressin stimulates NOS III. NO then directly stimulates Ca2+ entry through NCCE and, via protein kinase G, it inhibits CCE. The additional amplification provided by the involvement of guanylate cyclase and protein kinase G ensures that CCE will always be inhibited when vasopressin activates NCCE.

Hemin induces neuroglobin expression in neural cells

Blood ◽  
2002 ◽  
Vol 100 (7) ◽  
pp. 2494-2498 ◽  
Author(s):  
Yonghua Zhu ◽  
Yunjuan Sun ◽  
Kunlin Jin ◽  
David A. Greenberg
Keyword(s):  
Protein Kinase ◽  
Guanylate Cyclase ◽  
Kinase Inhibitor ◽  
Soluble Guanylate Cyclase ◽  
Fold Increase ◽  
Mitogen Activated Protein Kinase ◽  
Protein Kinase G ◽  
Neural Cells ◽  
Hypoxic Injury ◽  
Protein Levels

Neuroglobin is a newly identified vertebrate globin that binds O2 and is expressed in cerebral neurons. We found recently that neuronal expression of neuroglobin is stimulated by hypoxia and ischemia and protects neurons from hypoxic injury. Here we report that, like hemoglobin and myoglobin, neuroglobin expression can also be induced by hemin. Induction was concentration dependent and time dependent, with maximal (about 4-fold) increases in neuroglobin mRNA and protein levels occurring with 50 μM hemin and at 8 to 24 hours. The inductive effect of hemin was attenuated by the protein kinase G inhibitor KT5823 and the soluble guanylate cyclase inhibitor LY83583, was mimicked by treatment with 8-bromo–cyclic guanosine 3′,5′-monophosphate, and was accompanied by a greater than 10-fold increase in cGMP levels, suggesting that it is mediated through protein kinase G and soluble guanylate cyclase. In contrast, hypoxic induction of neuroglobin was blocked by the mitogen-activated protein kinase/extracellular signal–regulated kinase kinase inhibitor PD98059, indicating that hemin and hypoxia regulate neuroglobin expression by different mechanisms. These results provide evidence for regulation of neuroglobin expression by at least 2 signal transduction pathways.

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