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Yu H, Alruwaili N, Kelly MR, Zhang B, Liu A, Wang Y, Sun D, Wolin MS. Endothelin-1 depletion of cartilage oligomeric matrix protein modulates pulmonary artery superoxide and iron metabolism-associated mitochondrial heme biosynthesis. Am J Physiol Lung Cell Mol Physiol 2022; 323:L400-L409. [PMID: 35943724 PMCID: PMC9484992 DOI: 10.1152/ajplung.00534.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 08/03/2022] [Accepted: 08/05/2022] [Indexed: 11/22/2022] Open
Abstract
This study examines if heme biosynthesis-associated iron metabolism is regulated in pulmonary arteries by endothelin-1 (ET1) potentially through modulating cartilage oligomeric matrix protein (COMP) availability. Our studies in organoid-cultured endothelium-rubbed bovine pulmonary arteries (BPAs) observed COMP depletion by siRNA or hypoxia increases NOX2 and superoxide and depletes mitochondrial SOD2. ET1 also increases superoxide in a manner that potentially impairs mitochondrial heme biosynthesis. In this study, organoid culture of BPA with ET1 (10 nM) increases superoxide in the mitochondrial matrix and extramitochondrial regions associated with COMP depletion, and COMP (0.5 μM) inhibited these superoxide increases. As mitochondrial matrix superoxide could impair heme biosynthesis from protoporphyrin IX (PpIX) by decreasing Fe2+ availability and/or ferrochelatase (FECH), we studied ET1, COMP, and COMP siRNA effects on the expression of FECH, transferrin receptor-1 (TfR1, an indicator of iron availability) and soluble guanylate cyclase (sGC, a key heme-dependent protein), and on measurements of PpIX (HPLC) and heme content. ET1 decreased FECH, heme, and sGC, and increased TfR1 and iron. COMP reversed these effects of ET1, and COMP decreased PpIX and increased heme in the absence of ET1. COMP siRNA increased PpIX detection and TfR1 expression and decreased the expression of FECH and sGC. Nitric oxide (spermine NONOate) relaxation of BPA was inhibited by ET1, and this was attenuated by COMP during exposure to ET1. Thus, COMP depletion by ET1 or siRNA modulates pulmonary artery iron metabolism, which results in loss of heme biosynthesis and heme-dependent cGMP mechanisms.
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Affiliation(s)
- Hang Yu
- Department of Physiology, Harbin Medical University-Daqing, Daqing, China
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Norah Alruwaili
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Melissa R Kelly
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Bin Zhang
- Department of Physiology, New York Medical College, Valhalla, New York
- Department of Gastrointestinal Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Aijing Liu
- Department of Physiology, Harbin Medical University-Daqing, Daqing, China
| | - Yingqi Wang
- Department of Physiology, Harbin Medical University-Daqing, Daqing, China
| | - Dong Sun
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Michael S Wolin
- Department of Physiology, New York Medical College, Valhalla, New York
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Downregulated Recycling Process but Not De Novo Synthesis of Glutathione Limits Antioxidant Capacity of Erythrocytes in Hypoxia. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:7834252. [PMID: 32963701 PMCID: PMC7492869 DOI: 10.1155/2020/7834252] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/14/2020] [Accepted: 07/21/2020] [Indexed: 12/26/2022]
Abstract
Red blood cells (RBCs) are susceptible to sustained free radical damage during circulation, while the changes of antioxidant capacity and regulatory mechanism of RBCs under different oxygen gradients remain unclear. Here, we investigated the changes of oxidative damage and antioxidant capacity of RBCs in different oxygen gradients and identified the underlying mechanisms using an in vitro model of the hypoxanthine/xanthine oxidase (HX/XO) system. In the present study, we reported that the hypoxic RBCs showed much higher oxidative stress injury and lower antioxidant capacity compared with normoxic RBCs. In addition, we found that the disturbance of the recycling process, but not de novo synthesis of glutathione (GSH), accounted for the significantly decreased antioxidant capacity of hypoxic RBCs compared to normoxic RBCs. We further elucidated the underlying molecular mechanism by which oxidative phosphorylation of Band 3 blocked the hexose monophosphate pathway (HMP) and decreased NADPH production aggravating the dysfunction of GSH synthesis in hypoxic RBCs under oxidative conditions.
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Tawa M, Yamashita Y, Masuoka T, Nakano K, Yoshida J, Nishio M, Ishibashi T. Responsiveness of rat aorta and pulmonary artery to cGMP generators in the presence of thiol or heme oxidant. J Pharmacol Sci 2019; 140:43-47. [PMID: 31036520 DOI: 10.1016/j.jphs.2019.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/01/2019] [Accepted: 04/09/2019] [Indexed: 12/13/2022] Open
Abstract
This study investigated the effects of thiol and heme oxidants on responsiveness to cGMP generators in isolated rat aorta and pulmonary artery using an organ chamber. The nitric oxide (NO) donor sodium nitroprusside (SNP)-induced relaxation was impaired by exposure to the thiol oxidant diamide in both the aorta and the pulmonary artery, whereas the soluble guanylate cyclase (sGC) stimulator BAY 41-2272- or the sGC activator BAY 60-2770-induced relaxation was not affected. The impairment by diamide of SNP-induced aortic and pulmonary arterial relaxation was completely restored by post-treatment with the thiol reductant dithiothreitol. However, regardless of the vessel type, the relaxant response to SNP or BAY 41-2272 was impaired by exposure to the heme oxidant ODQ, whereas the response to BAY 60-2770 was enhanced. The ODQ-induced effects were reversed partially by post-treatment with the heme reductant dithionite. These findings indicate that thiol oxidation attenuates only the vascular responsiveness to NO donors and that heme oxidation attenuates the responsiveness to NO donors and sGC stimulators but augments that to sGC activators. Therefore, under oxidative stress, the order of usability of the vasodilators is suggested to be: NO donors < sGC stimulators < sGC activators.
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Affiliation(s)
- Masashi Tawa
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan.
| | - Yuka Yamashita
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Takayoshi Masuoka
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Katsuya Nakano
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Junko Yoshida
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Matomo Nishio
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Takaharu Ishibashi
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
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Beuve A. Thiol-Based Redox Modulation of Soluble Guanylyl Cyclase, the Nitric Oxide Receptor. Antioxid Redox Signal 2017; 26:137-149. [PMID: 26906466 PMCID: PMC5240013 DOI: 10.1089/ars.2015.6591] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/27/2016] [Accepted: 02/21/2016] [Indexed: 02/06/2023]
Abstract
SIGNIFICANCE Soluble guanylyl cyclase (sGC), which produces the second messenger cyclic guanosine 3', 5'-monophosphate (cGMP), is at the crossroads of nitric oxide (NO) signaling: sGC catalytic activity is both stimulated by NO binding to the heme and inhibited by NO modification of its cysteine (Cys) thiols (S-nitrosation). Modulation of sGC activity by thiol oxidation makes sGC a therapeutic target for pathologies originating from oxidative or nitrosative stress. sGC has an unusually high percentage of Cys for a cytosolic protein, the majority solvent exposed and therefore accessible modulatory targets for biological and pathophysiological signaling. Recent Advances: Thiol oxidation of sGC contributes to the development of cardiovascular diseases by decreasing NO-dependent cGMP production and thereby vascular reactivity. This thiol-based resistance to NO (e.g., increase in peripheral resistance) is observed in hypertension and hyperaldosteronism. CRITICAL ISSUES Some roles of specific Cys thiols have been identified in vitro. So far, it has not been possible to pinpoint the roles of specific Cys of sGC in vivo and to investigate the molecular mechanisms in an animal model. FUTURE DIRECTIONS The role of Cys as redox sensors, intermediates of activation, and mediators of change in sGC conformation, activity, and dimerization remains largely unexplored. To understand modulation of sGC activity, it is critical to investigate the roles of specific oxidative thiol modifications that are formed during these processes. Where the redox state of sGC thiols contribute to pathologies (vascular resistance and sGC desensitization by NO donors), it becomes crucial to design therapeutic strategies to restore sGC to its normal, physiological thiol redox state. Antioxid. Redox Signal. 26, 137-149.
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Affiliation(s)
- Annie Beuve
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School-Rutgers , Newark, New Jersey
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Rogers NM, Seeger F, Garcin ED, Roberts DD, Isenberg JS. Regulation of soluble guanylate cyclase by matricellular thrombospondins: implications for blood flow. Front Physiol 2014; 5:134. [PMID: 24772092 PMCID: PMC3983488 DOI: 10.3389/fphys.2014.00134] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/18/2014] [Indexed: 01/16/2023] Open
Abstract
Nitric oxide (NO) maintains cardiovascular health by activating soluble guanylate cyclase (sGC) to increase cellular cGMP levels. Cardiovascular disease is characterized by decreased NO-sGC-cGMP signaling. Pharmacological activators and stimulators of sGC are being actively pursued as therapies for acute heart failure and pulmonary hypertension. Here we review molecular mechanisms that modulate sGC activity while emphasizing a novel biochemical pathway in which binding of the matricellular protein thrombospondin-1 (TSP1) to the cell surface receptor CD47 causes inhibition of sGC. We discuss the therapeutic implications of this pathway for blood flow, tissue perfusion, and cell survival under physiologic and disease conditions.
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Affiliation(s)
- Natasha M Rogers
- Department of Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
| | - Franziska Seeger
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County Baltimore, MD, USA
| | - Elsa D Garcin
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County Baltimore, MD, USA
| | - David D Roberts
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, NIH Bethesda, MD, USA
| | - Jeffrey S Isenberg
- Department of Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine Pittsburgh, PA, USA ; Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
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Clanton TL, Hogan MC, Gladden LB. Regulation of cellular gas exchange, oxygen sensing, and metabolic control. Compr Physiol 2013; 3:1135-90. [PMID: 23897683 DOI: 10.1002/cphy.c120030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells must continuously monitor and couple their metabolic requirements for ATP utilization with their ability to take up O2 for mitochondrial respiration. When O2 uptake and delivery move out of homeostasis, cells have elaborate and diverse sensing and response systems to compensate. In this review, we explore the biophysics of O2 and gas diffusion in the cell, how intracellular O2 is regulated, how intracellular O2 levels are sensed and how sensing systems impact mitochondrial respiration and shifts in metabolic pathways. Particular attention is paid to how O2 affects the redox state of the cell, as well as the NO, H2S, and CO concentrations. We also explore how these agents can affect various aspects of gas exchange and activate acute signaling pathways that promote survival. Two kinds of challenges to gas exchange are also discussed in detail: when insufficient O2 is available for respiration (hypoxia) and when metabolic requirements test the limits of gas exchange (exercising skeletal muscle). This review also focuses on responses to acute hypoxia in the context of the original "unifying theory of hypoxia tolerance" as expressed by Hochachka and colleagues. It includes discourse on the regulation of mitochondrial electron transport, metabolic suppression, shifts in metabolic pathways, and recruitment of cell survival pathways preventing collapse of membrane potential and nuclear apoptosis. Regarding exercise, the issues discussed relate to the O2 sensitivity of metabolic rate, O2 kinetics in exercise, and influences of available O2 on glycolysis and lactate production.
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Affiliation(s)
- T L Clanton
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.
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Yamada S, Saitoh SI, Machii H, Mizukami H, Hoshino Y, Misaka T, Ishigami A, Takeishi Y. Coronary artery spasm related to thiol oxidation and senescence marker protein-30 in aging. Antioxid Redox Signal 2013; 19:1063-73. [PMID: 23320823 PMCID: PMC3771551 DOI: 10.1089/ars.2012.4903] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Senescence marker protein-30 (SMP30) decreases with aging, and SMP30 knockout (KO) mice show a short life with increased oxidant stress. AIMS We assessed the effect of oxidant stress with SMP30 deficiency in coronary artery spasm and clarify its underlying mechanisms. RESULTS We measured vascular responses to acetylcholine (ACh) and sodium nitroprusside (SNP) of isolated coronary arteries from SMP30 KO and wild-type (WT) mice. In SMP30 KO mice, ACh-induced vasoconstriction occurred, which was changed to vasodilation by dithiothreitol (DTT), a thiol-reducing agent. However, Nω-nitro-L-arginine-methyl ester, nitric oxide (NO) synthase inhibitor, or tetrahydrobiopterin did not change the ACh response. In isolated coronary arteries of WT mice, ACh-induced vasodilation occurred. Inhibition of glutathione reductase by 1, 3-bis(2-chloroethyl)-1-nitrosourea decreased ACh-induced vasodilation (n=10, p<0.01), which was restored by DTT. To evaluate the thiol oxidation, we measured the fluorescence of monochlorobimane (MCB) in coronary arteries, which covalently labels the total. The fluorescence level to MCB decreased in SMP30 KO mice, but with DTT treatment restored to a level comparable to that of WT mice. The reduced glutathione and total thiol levels were also low in the aorta of SMP30 KO mice compared with those of WT mice. Administration of ACh into the aortic sinus in vivo of SMP30 KO mice induced coronary artery spasm. INNOVATION The thiol redox state is a key regulator of endothelial NO synthase activity, and thiol oxidation was associated with endothelial dysfunction in the SMP30 deficiency model. CONCLUSION These results suggest that chronic thiol oxidation by oxidant stress is a trigger of coronary artery spasm, resulting in impaired endothelium-dependent vasodilation.
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Affiliation(s)
- Shinya Yamada
- 1 Department of Cardiology and Hematology, Fukushima Medical University , Fukushima, Japan
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8
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Heckler EJ, Crassous PA, Baskaran P, Beuve A. Protein disulfide-isomerase interacts with soluble guanylyl cyclase via a redox-based mechanism and modulates its activity. Biochem J 2013; 452:161-9. [PMID: 23477350 PMCID: PMC3992929 DOI: 10.1042/bj20130298] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
NO binds to the receptor sGC (soluble guanylyl cyclase), stimulating cGMP production. The NO-sGC-cGMP pathway is a key component in the cardiovascular system. Discrepancies in sGC activation and deactivation in vitro compared with in vivo have led to a search for endogenous factors that regulate sGC or assist in cellular localization. In our previous work, which identified Hsp (heat-shock protein) 70 as a modulator of sGC, we determined that PDI (protein disulfide-isomerase) bound to an sGC-affinity matrix. In the present study, we establish and characterize this interaction. Incubation of purified PDI with semi-purified sGC, both reduced and oxidized, resulted in different migration patterns on non-reducing Western blots indicating a redox component to the interaction. In sGC-infected COS-7 cells, transfected FLAG-tagged PDI and PDI CXXS (redox active site 'trap mutant') pulled down sGC. This PDI-sGC complex was resolved by reductant, confirming a redox interaction. PDI inhibited NO-stimulated sGC activity in COS-7 lysates, however, a PDI redox-inactive mutant PDI SXXS did not. Together, these data unveil a novel mechanism of sGC redox modulation via thiol-disulfide exchange. Finally, in SMCs (smooth muscle cells), endogenous PDI and sGC co-localize by in situ proximity ligation assay, which suggests biological relevance. PDI-dependent redox regulation of sGC NO sensitivity may provide a secondary control over vascular homoeostasis.
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Affiliation(s)
- Erin J Heckler
- Department of Pharmacology and Physiology, New Jersey Medical School, UMDNJ, Newark, NJ 07103, USA.
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9
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In vitro inhibition of human and rat platelets by NO donors, nitrosoglutathione, sodium nitroprusside and SIN-1, through activation of cGMP-independent pathways. Pharmacol Res 2011; 64:289-97. [PMID: 21539916 DOI: 10.1016/j.phrs.2011.03.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 11/23/2022]
Abstract
Three different NO donors, S-nitrosoglutathione (GSNO), sodium nitroprusside (SNP) and 3-morpholino-sydnonimine hydrochloride (SIN-1) were used in order to investigate mechanisms of platelet inhibition through cGMP-dependent and -independent pathways both in human and rat. To this purpose, we also evaluated to what extent cGMP-independent pathways were related with the entity of NO release from each drug. SNP, GSNO and SIN-1 (100 μM) effects on platelet aggregation, in the presence or absence of a soluble guanylate cyclase inhibitor (ODQ), on fibrinogen receptor (α(IIb)β(3)) binding to specific antibody (PAC-1), and on the entity of NO release from NO donors in human and rat platelet rich plasma (PRP) were measured. Inhibition of platelet aggregation (induced by ADP) resulted to be greater in human than in rat. GSNO was the most powerful inhibitor (IC(50) values, μM): (a) in human, GSNO=0.52±0.09, SNP=2.83 ± 0.53, SIN-1=2.98 ± 1.06; (b) in rat, GSNO = 28.4 ± 6.9, SNP = 265 ± 73, SIN-1=108 ± 85. GSNO action in both species was mediated by cGMP-independent mechanisms and characterized by the highest NO release in PRP. SIN-1 and SNP displayed mixed mechanisms of inhibition of platelet aggregation (cGMP-dependent and independent), except for SIN-1 in rat (cGMP-dependent), and respectively lower or nearly absent NO delivery. Conversely, all NO-donors prevalently inhibited PAC-1 binding to α(IIb)β(3) through cGMP-dependent pathways. A modest relationship between NO release from NO donors and cGMP-independent responses was found. Interestingly, the species difference in NO release from GSNO and inhibition by cGMP-independent mechanism was respectively attributed to S-nitrosylation of non-essential and essential protein SH groups.
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Abstract
Most current theories for the mechanism of hypoxic pulmonary vasoconstriction (HPV) include a role for reactive oxygen species and/or changes in redox regulation, but extreme controversy exists regarding which systems and redox changes mediate the HPV response. Nitric oxide (NO) appears to help to maintain low pulmonary arterial pressure, suppress HPV, and prevent the development of pulmonary hypertension. Our studies have found a key role for glucose-6-phosphate dehydrogenase in bovine pulmonary arterial smooth muscle functioning to maintain elevated levels of cytosolic NADPH which fuels the generation of vasodilator levels of hydrogen peroxide. HPV results from hypoxia removing vasodilation by peroxide. Decreased superoxide generation by Nox4 oxidase and its conversion to peroxide by Cu,Zn-SOD appear to be potential factors in sensing hypoxia, and decreased cGMP-associated vasodilation and removal of redox controlled vasodilator mechanisms by increased cytosolic NADPH may be key coordinators of the HPV response. Oxidant generation associated with vascular disease processes, including the removal of NO by superoxide, and attenuation of its ability to stimulate cGMP production by oxidation of the heme and thiols of soluble guanylate cyclase attenuate potential beneficial actions of NO on pulmonary arterial function. While pulmonary hypertension appears to have multiple poorly understood effects on redox-associated processes, potentially influencing responses to hypoxia and NO-cGMP signaling, much remains to be elucidated regarding how these processes may be important factors in the progression, expression and therapeutic treatment of pulmonary hypertension.
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11
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Zheng X, Ying L, Liu J, Dou D, He Q, Leung SWS, Man RYK, Vanhoutte PM, Gao Y. Role of sulfhydryl-dependent dimerization of soluble guanylyl cyclase in relaxation of porcine coronary artery to nitric oxide. Cardiovasc Res 2011; 90:565-72. [PMID: 21248051 DOI: 10.1093/cvr/cvr016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Soluble guanylyl cyclase (sGC) is a heterodimer. The dimerization of the enzyme is obligatory for its function in mediating actions caused by agents that elevate cyclic guanosine monophosphate (cGMP). The present study aimed to determine whether sGC dimerization is modulated by thiol-reducing agents and whether its dimerization influences relaxations in response to nitric oxide (NO). METHODS AND RESULTS The dimers and monomers of sGC and cGMP-dependent protein kinase (PKG) were analysed by western blotting. The intracellular cGMP content was measured by enzyme-linked immunosorbent assay. Changes in isometric tension were determined in organ chambers. In isolated porcine coronary arteries, the protein levels of sGC dimer were decreased by the thiol reductants dithiothreitol, l-cysteine, reduced l-glutathione and tris(2-carboxyethyl) phosphine. The effect was associated with reduced cGMP elevation and attenuated relaxations in response to nitric oxide donors. The dimerization of sGC and activation of the enzyme were also decreased by dihydrolipoic acid, an endogenous thiol antioxidant. Dithiothreitol at concentrations markedly affecting the dimerization of sGC had no significant effect on the dimerization of PKG or relaxation in response to 8-Br-cGMP. Relaxation of the coronary artery in response to a NO donor was potentiated by hypoxia when sGC was partly inhibited, coincident with an increase in sGC dimer and enhanced cGMP production. These effects were prevented by dithiothreitol and tris(2-carboxyethyl) phosphine. CONCLUSION These results demonstrate that the dimerization of sGC is exquisitely sensitive to thiol reductants compared with that of PKG, which may provide a novel mechanism for thiol-dependent modulation of NO-mediated vasodilatation in conditions such as hypoxia.
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Affiliation(s)
- Xiaoxu Zheng
- Department of Physiology and Pathophysiology, Peking University Health Science Center, 38 Xue Yuan Road, Beijing 100191, China
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Neo BH, Kandhi S, Ahmad M, Wolin MS. Redox regulation of guanylate cyclase and protein kinase G in vascular responses to hypoxia. Respir Physiol Neurobiol 2010; 174:259-64. [PMID: 20831906 PMCID: PMC2991487 DOI: 10.1016/j.resp.2010.08.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 08/19/2010] [Accepted: 08/31/2010] [Indexed: 11/26/2022]
Abstract
The production of cGMP by the soluble form of guanylate cyclase (sGC) in bovine pulmonary arteries (BPA) is controlled by cytosolic NADPH maintaining reduced thiol and heme sites on sGC needed for activation by NO, and the levels of Nox oxidase-derived superoxide and peroxide that influence pathways regulating sGC activity. Our recent studies in BPA suggest that the activities of peroxide metabolizing pathways in vascular smooth muscle potentially determine the balance between sGC stimulation by peroxide and a cGMP-independent activation of cGMP-dependent protein kinase (PKG) by a disulfide-mediated subunit dimerization. Cytosolic NADPH oxidation also appears to function in BPA through its influence on protein thiol redox control as an additional mechanism promoting vascular relaxation through PKG activation. These processes regulating PKG may participate in decreases in peroxide and increases in NADPH associated with contraction of BPA to hypoxia and in cytosolic NADPH oxidation potentially mediating bovine coronary artery relaxation to hypoxia.
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Affiliation(s)
- Boon Hwa Neo
- Department of Physiology, New York Medical College, Valhalla, NY 10595, United States
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13
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Wolin MS, Gupte SA, Mingone CJ, Neo BH, Gao Q, Ahmad M. Redox regulation of responses to hypoxia and NO-cGMP signaling in pulmonary vascular pathophysiology. Ann N Y Acad Sci 2010; 1203:126-32. [PMID: 20716294 DOI: 10.1111/j.1749-6632.2010.05557.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulmonary vascular responses elicited by hypoxia and NO-cGMP signaling are potentially influenced by ROS and redox mechanisms that change during the progression of disease processes. Our studies in endothelium-rubbed bovine pulmonary arteries suggest increased glucose-6-phosphate dehydrogenase levels (compared to coronary arteries) seem to maintain a tonic peroxide-mediated relaxation removed by hypoxia through NADPH fueling superoxide generation from Nox oxidase. The activities of glucose-6-phosphate dehydrogenase, oxidases (i.e., Nox4), and systems metabolizing superoxide and peroxide markedly influence hypoxic pulmonary vasoconstriction (HPV). Activation of soluble guanylate cyclase and cGMP protein kinase seems to participate in peroxide-elicited relaxation. Endogenous NO helps maintain low pulmonary arterial pressure and suppresses HPV. Multiple redox processes potentially occurring during the progression of pulmonary hypertension may also attenuate NO-mediated relaxation beyond its scavenging by superoxide, including oxidation of guanylate cyclase heme and thiols normally maintained by cytosolic NADPH redox control.
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Affiliation(s)
- Michael S Wolin
- Department of Physiology and Pulmonary Hypertension Center, New York Medical College, Valhalla, New York, USA.
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14
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Tsai EJ, Kass DA. Cyclic GMP signaling in cardiovascular pathophysiology and therapeutics. Pharmacol Ther 2009; 122:216-38. [PMID: 19306895 PMCID: PMC2709600 DOI: 10.1016/j.pharmthera.2009.02.009] [Citation(s) in RCA: 298] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 02/07/2023]
Abstract
Cyclic guanosine 3',5'-monophosphate (cGMP) mediates a wide spectrum of physiologic processes in multiple cell types within the cardiovascular system. Dysfunctional signaling at any step of the cascade - cGMP synthesis, effector activation, or catabolism - have been implicated in numerous cardiovascular diseases, ranging from hypertension to atherosclerosis to cardiac hypertrophy and heart failure. In this review, we outline each step of the cGMP signaling cascade and discuss its regulation and physiologic effects within the cardiovascular system. In addition, we illustrate how cGMP signaling becomes dysregulated in specific cardiovascular disease states. The ubiquitous role cGMP plays in cardiac physiology and pathophysiology presents great opportunities for pharmacologic modulation of the cGMP signal in the treatment of cardiovascular diseases. We detail the various therapeutic interventional strategies that have been developed or are in development, summarizing relevant preclinical and clinical studies.
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Affiliation(s)
- Emily J Tsai
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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Rogers SC, Said A, Corcuera D, McLaughlin D, Kell P, Doctor A. Hypoxia limits antioxidant capacity in red blood cells by altering glycolytic pathway dominance. FASEB J 2009; 23:3159-70. [PMID: 19417084 DOI: 10.1096/fj.09-130666] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The erythrocyte membrane is a newly appreciated platform for thiol-based circulatory signaling, and it requires robust free thiol maintenance. We sought to define physiological constraints on erythrocyte antioxidant defense. Hemoglobin (Hb) conformation gates glycolytic flux through the hexose monophosphate pathway (HMP), the sole source of nicotinamide adenine dinucleotide phosphate (NADPH) in erythrocytes. We hypothesized elevated intraerythrocytic deoxyHb would limit resilience to oxidative stress. Human erythrocytes were subjected to controlled oxidant (superoxide) loading following independent manipulation of oxygen tension, Hb conformation, and glycolytic pathway dominance. Sufficiency of antioxidant defense was determined by serial quantification of GSH, NADPH, NADH redox couples. Hypoxic erythrocytes demonstrated greater loss of reduction potential [Delta GSH E(hc) (mV): 123.4+/-9.7 vs. 57.2+/-11.1] and reduced membrane thiol (47.7+/-5.7 vs. 20.1+/-4.3%) (hypoxia vs. normoxia, respectively; P<0.01), a finding mimicked in normoxic erythrocytes after HMP blockade. Rebalancing HMP flux during hypoxia restored resilience to oxidative stress at all stages of the system. Cell-free studies assured oxidative loading was not altered by oxygen tension, heme ligation, or the inhibitors employed. These data indicate that Hb conformation controls coupled glucose and thiol metabolism in erythrocytes, and implicate hypoxemia in the pathobiology of erythrocyte-based vascular signaling.
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Affiliation(s)
- Stephen C Rogers
- Department of Pediatrics, Washington University in St. Louis, St. Louis, MO, USA
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Abstract
This article summarizes perspectives on how reactive oxygen species (ROS) and redox signaling mechanisms participate in regulating vascular smooth muscle function that have resulted from our studies over the past 25 years in areas including oxygen sensing and the regulation of cGMP production by soluble guanylate cyclase (sGC) that were presented in the Robert M. Berne Distinguished Lectureship at the 2008 Experimental Biology Meeting. It considers mechanisms controlling the activity of sources of ROS including Nox oxidases and mitochondria by physiological stimuli, vascular diseases processes, and metabolic mechanisms linked to NAD(P)H redox and hypoxia. Metabolic interactions of individual ROS such as hydrogen peroxide with cellular peroxide metabolizing enzymes are viewed as some of the most sensitive ways of influencing cellular signaling systems. The control of cytosolic NADPH redox also seems to be a major contributor to bovine coronary arterial relaxation to hypoxia, where its oxidation functions to coordinate the lowering of intracellular calcium, whereas increased cytosolic NADPH generation in pulmonary arteries appears to maintain elevated Nox oxidase activity, and relaxation to hydrogen peroxide, which is attenuated by hypoxia. The sensitivity of sGC to nitric oxide seems to be regulated by thiol and heme redox systems controlled by cytosolic NADPH. Heme biosynthesis and metabolism are also important factors regulating the sGC system. The signaling pathways controlling oxidases and their colocalization with redox-regulated systems enables selective activation of numerous regulatory mechanisms influencing vascular function in physiological processes and the progression of aging-associated vascular diseases.
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Affiliation(s)
- Michael S Wolin
- Dept. of Physiology, Basic Science Bldg., Rm 604, New York Medical College, Valhalla, NY 10595, USA.
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Gupte SA, Wolin MS. Oxidant and redox signaling in vascular oxygen sensing: implications for systemic and pulmonary hypertension. Antioxid Redox Signal 2008; 10:1137-52. [PMID: 18315496 PMCID: PMC2443404 DOI: 10.1089/ars.2007.1995] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
It has been well known for >100 years that systemic blood vessels dilate in response to decreases in oxygen tension (hypoxia; low PO2), and this response appears to be critical to supply blood to the stressed organ. Conversely, pulmonary vessels constrict to a decrease in alveolar PO2 to maintain a balance in the ventilation-to-perfusion ratio. Currently, although little question exists that the PO2 affects vascular reactivity and vascular smooth muscle cells (VSMCs) act as oxygen sensors, the molecular mechanisms involved in modulating the vascular reactivity are still not clearly understood. Many laboratories, including ours, have suggested that the intracellular calcium concentration ([Ca2+]i), which regulates vasomotor function, is controlled by free radicals and redox signaling, including NAD(P)H and glutathione (GSH) redox. In this review article, therefore, we discuss the implications of redox and oxidant alterations seen in pulmonary and systemic hypertension, and how key targets that control [Ca2+]i, such as ion channels, Ca2+ release from internal stores and uptake by the sarcoplasmic reticulum, and the Ca2+ sensitivity to the myofilaments, are regulated by changes in intracellular redox and oxidants associated with vascular PO2sensing in physiologic or pathophysiologic conditions.
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Affiliation(s)
- Sachin A Gupte
- Department of Physiology, New York Medical College, Valhalla, New York 10595, USA.
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Mingone CJ, Ahmad M, Gupte SA, Chow JL, Wolin MS. Heme oxygenase-1 induction depletes heme and attenuates pulmonary artery relaxation and guanylate cyclase activation by nitric oxide. Am J Physiol Heart Circ Physiol 2008; 294:H1244-50. [PMID: 18178725 DOI: 10.1152/ajpheart.00846.2007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This study examines in endothelium-denuded bovine pulmonary arteries the effects of increasing heme oxygenase-1 (HO-1) activity on relaxation and soluble guanylate cyclase (sGC) activation by nitric oxide (NO). A 24-h organ culture with 0.1 mM cobalt chloride (CoCl2) or 30 microM Co-protoporphyrin IX was developed as a method of increasing HO-1 expression. These treatments increased HO-1 expression and HO activity by approximately two- to fourfold and lowered heme levels by 40-45%. Induction of HO-1 was associated with an attenuation of pulmonary arterial relaxation to the NO-donor spermine-NONOate. The presence of a HO-1 inhibitor 30 microM chromium mesoporphyrin during the 24-h organ culture (but not acute treatment with this agent) reversed the attenuation of relaxation to NO seen in arteries co-cultured with agents that increased HO-1. Relaxation to isoproterenol, which is thought to be mediated through cAMP, was not altered in arteries with increased HO-1. Inducers of HO-1 did not appear to alter basal sGC activity in arterial homogenates or expression of the beta(1)-subunit of sGC. However, the increase in activity seen in the presence of 1 microM spermine-NONOate was attenuated in homogenates obtained from arteries with increased HO-1. Since arteries with increased HO-1 had decreased levels of superoxide detected by the chemiluminescence of 5 microM lucigenin, superoxide did not appear to be mediating the attenuation of relaxation to NO. These data suggest that increasing HO-1 activity depletes heme, and this is associated with an attenuation of pulmonary artery relaxation and sGC activation responses to NO.
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Saitoh SI, Kiyooka T, Rocic P, Rogers PA, Zhang C, Swafford A, Dick GM, Viswanathan C, Park Y, Chilian WM. Redox-dependent coronary metabolic dilation. Am J Physiol Heart Circ Physiol 2007; 293:H3720-5. [PMID: 17965288 DOI: 10.1152/ajpheart.00436.2007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have observed that hydrogen peroxide (H2O2), the dismutated product of superoxide, is a coronary metabolic dilator and couples myocardial oxygen consumption to coronary blood flow. Because the chemical activity of H2O2 favors its role as an oxidant, and thiol groups are susceptible to oxidation, we hypothesized that coronary metabolic dilation occurs via a redox mechanism involving thiol oxidation. To test this hypothesis, we studied the mechanisms of dilation of isolated coronary arterioles to metabolites released by metabolically active (paced at 400 min) isolated cardiac myocytes and directly compared these responses with authentic H2O2. Studies were performed under control conditions and using interventions designed to reduce oxidized thiols [0.1 microM dithiothreitol (DTT) and 10 mM N-acetyl-L-cysteine (NAC)]. Aliquots of the conditioned buffer from paced myocytes produced vasodilation of isolated arterioles (peak response, 71% +/- 6% of maximal dilation), whereas H2O2 produced complete dilation (92% +/- 7%). Dilation to either the conditioned buffer or to H2O2 was significantly reduced by the administration of either NAC or DTT. The location of the thiols oxidized by the conditioned buffer or of H2O2 was determined by the administration of the fluorochromes monochlorobimane (20 microM) or monobromotrimethylammoniobimane (20 microM), which covalently label the reduced total or extracellular-reduced thiols, respectively. H2O2 or the conditioned buffer predominantly oxidized intracellular thiols since the fluorescent signal from monochlorobimane was reduced more than that of monobromotrimethylammoniobimane. To determine whether one of the intracellular targets of thiol oxidation that leads to dilation is the redox-sensitive kinase p38 mitogen-activated protein (MAP) kinase, we evaluated dilation following the administration of the p38 inhibitor SB-203580 (10 microM). The inhibition of p38 attenuated dilation to either H2O2 or to the conditioned buffer from stimulated myocytes by a similar degree, but SB-203580 did not attenuate dilation to nitroprusside. Western blot analysis for the activated form of p38 (phospho-p38) in the isolated aortae revealed robust activation of this enzyme by H2O2. Taken together, our results show that an active component of cardiac metabolic dilation, like that of H2O2, produces dilation by the oxidation of thiols, which are predominantly intracellular and dependent activation on the p38 MAP kinase. Thus coronary metabolic dilation appears to be mediated by redox-dependent signals.
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Affiliation(s)
- Shu-ichi Saitoh
- Department of Integrative Medical Sciences, Northeastern Ohio University College of Medicine, 4209 State Rte. 44, Rootstown, OH 44272-0095, USA
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Sayed N, Baskaran P, Ma X, van den Akker F, Beuve A. Desensitization of soluble guanylyl cyclase, the NO receptor, by S-nitrosylation. Proc Natl Acad Sci U S A 2007; 104:12312-7. [PMID: 17636120 PMCID: PMC1940331 DOI: 10.1073/pnas.0703944104] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The molecular mechanism of desensitization of soluble guanylyl cyclase (sGC), the NO receptor, has long remained unresolved. Posttranslational modification and redox state have been postulated to affect sGC sensitivity to NO but evidence has been lacking. We now show that sGC can be S-nitrosylated in primary aortic smooth muscle cells by S-nitrosocysteine (CSNO), an S-nitrosylating agent, in human umbilical vein endothelial cells after vascular endothelial growth factor treatment and in isolated aorta after sustained exposure to acetylcholine. Importantly, we show that S-nitrosylation of sGC results in decreased responsiveness to NO characterized by loss of NO-stimulated sGC activity. Desensitization of sGC is concentration- and time-dependent on exposure to CSNO, and sensitivity of sGC to NO can be restored and its S-nitrosylation prevented with cellular increase of thiols. We confirm in vitro with semipurified sGC that S-nitrosylation directly causes desensitization, suggesting that other cellular factors are not required. Two potential S-nitrosylated cysteines in the alpha- and beta-subunits of sGC were identified by MS. Replacement of these cysteines, C243 in alpha and C122 in beta, created mutants that were mostly resistant to desensitization. Structural analysis of the region near beta-C122 in the homologous Nostoc H-NOX crystal structure indicates that this residue is in the vicinity of the heme and its S-nitrosylation could dampen NO activation by affecting the positions of key residues interacting with the heme. This study suggests that S-nitrosylation of sGC is a means by which memory of NO exposure is kept in smooth muscle cells and could be a mechanism of NO tolerance.
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Affiliation(s)
- Nazish Sayed
- *Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103; and
| | - Padmamalini Baskaran
- *Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103; and
| | - Xiaolei Ma
- Department of Biochemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106
| | - Focco van den Akker
- Department of Biochemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106
| | - Annie Beuve
- *Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103; and
- To whom correspondence should be addressed. E-mail:
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Wolin MS, Ahmad M, Gao Q, Gupte SA. Cytosolic NAD(P)H regulation of redox signaling and vascular oxygen sensing. Antioxid Redox Signal 2007; 9:671-8. [PMID: 17511583 DOI: 10.1089/ars.2007.1559] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This article considers how regulation of signaling controlled by cytosolic NADPH and NADH redox systems contained within the vascular smooth muscle cell may contribute to coordinating alterations in force generation elicited by acute changes in oxygen tension. Additional important issues considered include defining when oxidases generating reactive oxygen species (ROS), such as Nox oxidases, or ROS metabolizing activities which utilize cytosolic NADH and/or NADPH are key participants in eliciting responses that are observed, and assessing how mitochondria can potentially contribute to the regulation that is seen. Many important signaling mechanisms potentially involved in vascular oxygen sensing such as potassium channels, systems regulating intracellular calcium, and the sensitivity of the contractile apparatus to calcium, and the control of cGMP-mediated relaxation by soluble guanylate cyclase appear to be regulated by cytosolic NAD(P)H redox and or ROS. Differences in the processes controlling the maintenance of cytosolic NADPH redox by the pentose phosphate pathway of glucose metabolism are hypothesized to be a key factor in controlling the expression of a relaxation to hypoxia seen in systemic arteries compared to the hypoxic contractile response observed in pulmonary arterial smooth muscle.
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Affiliation(s)
- Michael S Wolin
- Department of Physiology, New York Medical College, Valhalla, New York 10595, USA.
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Perkins WJ, Taniguchi M, Warner DO, Chini EN, Jones KA. Reduction in soluble guanylyl cyclase-specific activity following prolonged treatment of porcine pulmonary artery with nitric oxide. Am J Physiol Lung Cell Mol Physiol 2007; 293:L84-95. [PMID: 17384083 DOI: 10.1152/ajplung.00368.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In a newly characterized cultured porcine pulmonary artery (PA) preparation, 24-h treatment with the nitric oxide (NO) donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO) decreased the response to acutely applied DETA-NO compared with 24-h control (-log EC(50) 6.55 +/- 0.12 and 5.02 +/- 0.21, respectively). Treatment of PA with the cell-permeable superoxide dismutase mimetic, Mn(III) tetra(4-benzoic acid) porphyrin chloride, did not change NO responsiveness in either freshly prepared or 24-h DETA-NO-treated PA. cGMP and cAMP phosphodiesterase activities were approximately equal in PA. Twenty-four-hour DETA-NO treatment did not change either cGMP or cAMP phosphodiesterase activities. Twenty-four hours in culture had no significant effect on soluble guanylyl cyclase (sGC) subunit mRNA expression, but 24-h DETA-NO treatment significantly decreased the expression of both sGCalpha(1) and sGCbeta(1). sGCbeta(1) protein expression was 42 +/- 4 ng/mg soluble protein. Twenty-four hours in culture without and with DETA-NO reduced sGCbeta(1) protein expression (36 +/- 3 and 31 +/- 3 ng/mg soluble protein, respectively, P < 0.025). Basal tissue cGMP [(cGMP)(i)] was significantly increased, and NO-induced (cGMP)(i) was significantly decreased by 24-h DETA-NO treatment. (cGMP)(i) normalized to the amount of sGC protein expressed in PA was significantly lower in PA treated for 24 h with DETA-NO compared with both freshly isolated and 24-h cultured PA. We conclude that prolonged NO treatment induces decreased acute NO responsiveness in part by decreasing both sGC expression and sGC-specific activity.
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Affiliation(s)
- William J Perkins
- Department of Anesthesiology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA.
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Schach C, Xu M, Platoshyn O, Keller SH, Yuan JXJ. Thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels. Am J Physiol Lung Cell Mol Physiol 2006; 292:L685-98. [PMID: 17098807 DOI: 10.1152/ajplung.00276.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cellular redox change regulates pulmonary vascular tone by affecting function of membrane and cytoplasmic proteins, enzymes, and second messengers. This study was designed to test the hypothesis that functional modulation of ion channels by thiol oxidation contributes to regulation of excitation-contraction coupling in isolated pulmonary artery (PA) rings. Acute treatment with the thiol oxidant diamide produced a dose-dependent relaxation in PA rings; the IC50 was 335 and 58 microM for 40 mM K+ - and 2 microM phenylephrine-induced PA contraction, respectively. The diamide-mediated pulmonary vasodilation was affected by neither functional removal of endothelium nor 8-bromoguanosine-3'-5'-cyclic monophosphate (50 microM) and HA-1004 (30 microM). A rise in extracellular K+ concentration (from 20 to 80 mM) attenuated the thiol oxidant-induced PA relaxation. Passive store depletion by cyclopiazonic acid (50 microM) and active store depletion by phenylephrine (in the absence of external Ca2+ both induced PA contraction due to capacitative Ca2+ entry. Thiol oxidation by diamide significantly attenuated capacitative Ca2+ entry-induced PA contraction due to active and passive store depletion. The PA rings isolated from left and right PA branches appeared to respond differently to store depletion. Although the active tension induced by passive store depletion was comparable, the active tension induced by active store depletion was 3.5-fold greater in right branches than in left branches. These data indicate that thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels, which subsequently attenuate Ca2+ influx and decrease cytosolic free Ca2+ concentration in pulmonary artery smooth muscle cells. The mechanisms involved in thiol oxidation-mediated pulmonary vasodilation or activation of K+ channels and inhibition of store-operated Ca2+ channels appear to be independent of functional endothelium and of the cGMP-dependent protein kinase pathway.
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Affiliation(s)
- Christian Schach
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0725, La Jolla, CA 92093-0725, USA
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Mingone CJ, Gupte SA, Chow JL, Ahmad M, Abraham NG, Wolin MS. Protoporphyrin IX generation from δ-aminolevulinic acid elicits pulmonary artery relaxation and soluble guanylate cyclase activation. Am J Physiol Lung Cell Mol Physiol 2006; 291:L337-44. [PMID: 16899710 DOI: 10.1152/ajplung.00482.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Protoporphyrin IX is an activator of soluble guanylate cyclase (sGC), but its role as an endogenous regulator of vascular function through cGMP has not been previously reported. In this study we examined whether the heme precursor δ-aminolevulinic acid (ALA) could regulate vascular force through promoting protoporphyrin IX-elicited activation of sGC. Exposure of endothelium-denuded bovine pulmonary arteries (BPA) in organoid culture to increasing concentrations of the heme precursor ALA caused a concentration-dependent increase in BPA epifluorescence, consistent with increased tissue protoporphyrin IX levels, associated with decreased force generation to increasing concentrations of serotonin. The force-depressing actions of 0.1 mM ALA were associated with increased cGMP-associated vasodilator-stimulated phosphoprotein (VASP) phosphorylation and increased sGC activity in homogenates of BPA cultured with ALA. Increasing iron availability with 0.1 mM FeSO4inhibited the decrease in contraction to serotonin and increase in sGC activity caused by ALA, associated with decreased protoporphyrin IX and increased heme. Chelating endogenous iron with 0.1 mM deferoxamine increased the detection of protoporphyrin IX and force depressing activity of 10 μM ALA. The inhibition of sGC activation with the heme oxidant 10 μM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) attenuated the force depressing actions of an NO donor without altering the actions of ALA. Thus control of endogenous formation of protoporphyrin IX from ALA by the availability of iron is potentially a novel physiological mechanism of controlling vascular function through regulating the activity of sGC.
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Perkins WJ. Regulation of soluble guanylyl cyclase: looking beyond NO. Am J Physiol Lung Cell Mol Physiol 2006; 291:L334-6. [PMID: 16714333 DOI: 10.1152/ajplung.00158.2006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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