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Zhang M, Song P, Xu J, Zou MH. Activation of NAD(P)H oxidases by thromboxane A2 receptor uncouples endothelial nitric oxide synthase. Arterioscler Thromb Vasc Biol 2011; 31:125-32. [PMID: 20947827 PMCID: PMC3005129 DOI: 10.1161/atvbaha.110.207712] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE The thromboxane receptor (TPr) and multiple TPr ligands, including thromboxane A(2) (TxA(2)) and prostaglandin H(2), are elevated during vascular and atherothrombotic diseases. How TPr stimulation causes vascular injury remains poorly defined. This study was conducted to investigate the mechanism by which TPr stimulation leads to vascular injury. METHODS AND RESULTS Exposure of bovine aortic endothelial cells to either [1S-(1α,2β(5Z),3α(1E,3R),4α]-7-[3-(3-hydroxy-4-(d'-iodophenoxy)-1-butenyl)-7-oxabicyclo-[2.2.1] heptan-2-yl]-5'-heptenoic acid (IBOP) or U46619, 2 structurally related TxA(2) mimetics, for 24 hours markedly increased the release of superoxide anions (O(2)(·-)) and peroxynitrite (ONOO(-)) but reduced cyclic GMP, an index of nitric oxide bioactivity. IBOP also significantly suppressed activity of endothelial nitric oxide synthase (eNOS), increased enzyme-inactive eNOS monomers, and reduced levels of tetrahydrobiopterin, an essential eNOS cofactor. IBOP- and U46619-induced increases in O(2)(·-) were accompanied by the membrane translocation of the p67(phox) subunit of NAD(P)H oxidase. Pharmacological or genetic inhibition of either NAD(P)H oxidase or TPr abolished IBOP-induced O(2)(·-) formation. Furthermore, TPr activation significantly increased protein kinase C-ζ (PKC-ζ) in membrane fractions and PKC-ζ phosphorylation at Thr410. Consistently, PKC-ζ inhibition abolished TPr activation-induced membrane translocation of p67(phox) and O(2)(·-) production. Finally, exposure of isolated mouse aortae to IBOP markedly increased O(2)(·-) in wild-type but not in those from gp91(phox) knockout mice. CONCLUSIONS We conclude that TPr activation via PKC-ζ-mediated NAD(P)H oxidase activation increases both O(2)(·-) and ONOO(-), resulting in eNOS uncoupling in endothelial cells.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Animals
- Apoptosis/drug effects
- Biopterins/analogs & derivatives
- Biopterins/metabolism
- Bridged Bicyclo Compounds, Heterocyclic/pharmacology
- Cattle
- Cell Survival/drug effects
- Cells, Cultured
- Cyclic GMP/metabolism
- Cytochrome P-450 Enzyme System/metabolism
- Endothelial Cells/drug effects
- Endothelial Cells/enzymology
- Endothelial Cells/pathology
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Fatty Acids, Unsaturated/pharmacology
- Intramolecular Oxidoreductases/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- NADPH Oxidases/antagonists & inhibitors
- NADPH Oxidases/genetics
- NADPH Oxidases/metabolism
- Nitric Oxide/metabolism
- Nitric Oxide Synthase Type III/metabolism
- Oxidative Stress/drug effects
- Peroxynitrous Acid/metabolism
- Phosphoproteins/metabolism
- Phosphorylation
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- Protein Processing, Post-Translational
- Protein Transport
- RNA Interference
- Receptors, Immunologic/deficiency
- Receptors, Immunologic/genetics
- Receptors, Thromboxane A2, Prostaglandin H2/agonists
- Receptors, Thromboxane A2, Prostaglandin H2/metabolism
- Signal Transduction/drug effects
- Superoxides/metabolism
- Time Factors
- Tyrosine/analogs & derivatives
- Tyrosine/metabolism
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Affiliation(s)
- Miao Zhang
- Department of Biochemistry and Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Ping Song
- Department of Biochemistry and Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Jian Xu
- Department of Biochemistry and Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Ming-Hui Zou
- Department of Biochemistry and Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
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Shi G, Morrell CN. Platelets as initiators and mediators of inflammation at the vessel wall. Thromb Res 2010; 127:387-90. [PMID: 21094986 DOI: 10.1016/j.thromres.2010.10.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 10/15/2010] [Accepted: 10/17/2010] [Indexed: 01/16/2023]
Abstract
Platelets are dynamic cells with activities that extend beyond thrombosis including an important role in initiating and sustaining vascular inflammation. A role for platelets has been described in many physiologic and pathophysiologic processes such as atherosclerosis, stem cell trafficking, tumor metastasis, and arthritis. Platelet activation at sites of an intact inflamed endothelium contributes to vascular inflammation and vascular wall remodeling. Platelets secrete a wide array of preformed and synthesized inflammatory mediators upon activation that can exert significant local and systemic effects. This review will focus on the role of platelet derived mediators in vascular inflammation and vascular wall remodeling.
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Affiliation(s)
- Guanfang Shi
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Box CVRI, Rochester, New York 14642, USA
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53
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Han Y, Wang Q, Song P, Zhu Y, Zou MH. Redox regulation of the AMP-activated protein kinase. PLoS One 2010; 5:e15420. [PMID: 21079763 PMCID: PMC2974634 DOI: 10.1371/journal.pone.0015420] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 09/21/2010] [Indexed: 01/16/2023] Open
Abstract
Redox state is a critical determinant of cell function, and any major imbalances can cause severe damage or death.
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Affiliation(s)
- Yingying Han
- Department of Biochemistry and Department of Medicine, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
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54
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Ball SK, Field MC, Tippins JR. Regulation of thromboxane receptor signaling at multiple levels by oxidative stress-induced stabilization, relocation and enhanced responsiveness. PLoS One 2010; 5:e12798. [PMID: 20856817 PMCID: PMC2939892 DOI: 10.1371/journal.pone.0012798] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Accepted: 08/16/2010] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Thromboxane A(2) (TxA(2)) is a major, unstable arachidonic acid metabolite, and plays a key role in normal physiology and control of vascular tone. The human thromboxane receptor (TPβ), expressed in COS-7 cells, is located predominantly in the endoplasmic reticulum (ER). Brief hydrogen peroxide exposure increases the efficiency of translocation of TPβ from the ER into the Golgi complex, inducing maturation and stabilization of TPβ. However, the ultimate fate of this post-ER TPβ pool is not known, nor is its capacity to initiate signal transduction. Here we specifically assessed if functional TPβ was transported to the plasma membrane following H(2)O(2) exposure. RESULTS We demonstrate, by biotinylation and confocal microscopy, that exposure to H(2)O(2) results in rapid delivery of a cohort of TPβ to the cell surface, which is stable for at least eight hours. Surface delivery is brefeldin A-sensitive, indicating that translocation of this receptor cohort is from internal pools and via the Golgi complex. H(2)O(2) treatment results in potentiation of the increase to intracellular calcium concentrations in response to TPβ agonists U46619 and 8-iso PGF(2α) and also in the loss of ligand-dependent receptor internalization. Further there is increased responsiveness to a second application of the agonist. Finally we demonstrate that the effect of H(2)O(2) on stimulating surface delivery is shared with the FP prostanoid receptor but not the EP3 or EP4 receptors. CONCLUSIONS/SIGNIFICANCE In summary, brief exposure to H(2)O(2) results in an immediate and sustained increase in the surface pool of thromboxane receptor that is capable of mediating a persistent hyper-responsiveness of the cell and suggests a highly sophisticated mechanism for rapidly regulating thromboxane signaling.
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Affiliation(s)
- Stephen K. Ball
- Division of Cell and Molecular Biology, Imperial College, London, United Kingdom
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Mark C. Field
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - John R. Tippins
- Division of Cell and Molecular Biology, Imperial College, London, United Kingdom
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Abstract
AbstractAdenosine Monophosphate-activated Protein Kinase (AMPK), a serine/threonine kinase and a member of the Snf1/AMPK protein kinase family, consists of three protein subunits that together make a functional enzyme. AMPK, which is expressed in a number of tissues, including the liver, brain, and skeletal muscle, is allosterically activated by a rise in the AMP: ATP ratio (ie in a low ATP or energy depleted state). The net effect of AMPK activation is to halt energy consuming (anabolic) pathways but to promote energy conserving (catabolic) cellular pathways. AMPK has therefore often been dubbed the "metabolic master switch". AMPK also plays a critical physiological role in the cardiovascular system. Increasing evidence suggest that AMPK might also function as a sensor by responding to oxidative stress. Mostly importantly, AMPK modulates endogenous antioxidant gene expression and/or suppress the production of oxidants. AMPK promotes cardiovascular homeostasis by ensuring an optimum redox balance on the heart and vascular tissues. Dysfunctional AMPK is thought to underlie several cardiovascular pathologies. Here we review this kinase from its structure and discovery to current knowledge of its adaptive and maladaptive role in the cardiovascular system.
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56
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Zmijewski JW, Banerjee S, Bae H, Friggeri A, Lazarowski ER, Abraham E. Exposure to hydrogen peroxide induces oxidation and activation of AMP-activated protein kinase. J Biol Chem 2010; 285:33154-33164. [PMID: 20729205 DOI: 10.1074/jbc.m110.143685] [Citation(s) in RCA: 295] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Although metabolic conditions associated with an increased AMP/ATP ratio are primary factors in the activation of 5'-adenosine monophosphate-activated protein kinase (AMPK), a number of recent studies have shown that increased intracellular levels of reactive oxygen species can stimulate AMPK activity, even without a decrease in cellular levels of ATP. We found that exposure of recombinant AMPKαβγ complex or HEK 293 cells to H(2)O(2) was associated with increased kinase activity and also resulted in oxidative modification of AMPK, including S-glutathionylation of the AMPKα and AMPKβ subunits. In experiments using C-terminal truncation mutants of AMPKα (amino acids 1-312), we found that mutation of cysteine 299 to alanine diminished the ability of H(2)O(2) to induce kinase activation, and mutation of cysteine 304 to alanine totally abrogated the enhancing effect of H(2)O(2) on kinase activity. Similar to the results obtained with H(2)O(2)-treated HEK 293 cells, activation and S-glutathionylation of the AMPKα subunit were present in the lungs of acatalasemic mice or mice treated with the catalase inhibitor aminotriazole, conditions in which intracellular steady state levels of H(2)O(2) are increased. These results demonstrate that physiologically relevant concentrations of H(2)O(2) can activate AMPK through oxidative modification of the AMPKα subunit. The present findings also imply that AMPK activation, in addition to being a response to alterations in intracellular metabolic pathways, is directly influenced by cellular redox status.
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Affiliation(s)
- Jaroslaw W Zmijewski
- From the Department of Medicine, Birmingham, Alabama 35294-0012; Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0012.
| | - Sami Banerjee
- From the Department of Medicine, Birmingham, Alabama 35294-0012
| | - Hongbeom Bae
- From the Department of Medicine, Birmingham, Alabama 35294-0012; Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
| | - Arnaud Friggeri
- From the Department of Medicine, Birmingham, Alabama 35294-0012
| | - Eduardo R Lazarowski
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7248
| | - Edward Abraham
- From the Department of Medicine, Birmingham, Alabama 35294-0012; Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0012.
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Hou X, Song J, Li XN, Zhang L, Wang X, Chen L, Shen YH. Metformin reduces intracellular reactive oxygen species levels by upregulating expression of the antioxidant thioredoxin via the AMPK-FOXO3 pathway. Biochem Biophys Res Commun 2010; 396:199-205. [PMID: 20398632 DOI: 10.1016/j.bbrc.2010.04.017] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Accepted: 04/05/2010] [Indexed: 12/25/2022]
Abstract
BACKGROUND Oxidative stress induced by free fatty acids plays a critical role in the pathogenesis of endothelial dysfunction and atherosclerosis in patients with metabolic syndrome. Reducing oxidative stress in these patients may prevent cardiovascular complications. The antidiabetic agent metformin has been reported to directly protect the cardiovascular system. In this study, we examined the effect of metformin on the intracellular levels of reactive oxygen species (ROS) induced by palmitic acid (PA) in human aortic endothelial cells and studied the molecular mechanisms involved. METHODS AND RESULTS We observed that metformin significantly reduced intracellular ROS levels induced by PA. Additionally, metformin increased the expression of the antioxidant thioredoxin (Trx), which mediated metformin's effects on ROS reduction. Metformin increased Trx expression through the AMP-activated protein kinase (AMPK) pathway. Metformin-regulated Trx at the transcriptional level and forkhead transcription factor 3 (FOXO3) was involved in this process. CONCLUSION These results suggest that metformin reduces ROS levels by inducing Trx expression through activation of the AMPK-FOXO3 pathway.
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Affiliation(s)
- Xinguo Hou
- Qilu Hospital, Shandong University, Jinan, Shandong, China
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58
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Liu C, Liang B, Wang Q, Wu J, Zou MH. Activation of AMP-activated protein kinase alpha1 alleviates endothelial cell apoptosis by increasing the expression of anti-apoptotic proteins Bcl-2 and survivin. J Biol Chem 2010; 285:15346-15355. [PMID: 20233722 DOI: 10.1074/jbc.m110.102491] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Accumulating evidence suggests that AMP-activated protein kinase (AMPK) activation exerts anti-apoptotic effects in multiple types of cells. However, the underlying mechanisms remain poorly defined. The aim of the present study was to determine how AMPK suppresses apoptosis in endothelial cells exposed to hypoxia and glucose deprivation (OGD). AMPK activity, NF-kappaB activation, and endothelial cell apoptosis were assayed in cultured endothelial cells and mouse common carotid artery with or without OGD treatment. OGD markedly activated AMPK as early as 30 min, and AMPK activity reached maximal at 2 h of OGD. Endothelial apoptosis was not detected until 2 h of OGD but became markedly elevated at 6 h of OGD treatment. Furthermore, AMPK inhibition by Compound C or overexpression of dominant negative AMPK (AMPK-DN) exacerbated, whereas AMPK activation by pharmacologic (aminoimidazole carboxamide ribonucleotide (AICAR)) or genetic means (overexpression of constitutively active AMPK) suppressed endothelial cell apoptosis caused by OGD. Concomitantly, AMPK activation increased the expression of both Bcl-2 and Survivin, two potent anti-apoptotic proteins. Furthermore, AMPK activation significantly enhanced IkappaBalpha kinase activation, NF-kappaB nuclear translocation, and DNA binding activity of NF-kappaB. Consistently, selective inhibition of NF-kappaB, which abolished OGD-enhanced expression of Bcl-2 and Survivin, accentuated endothelial apoptosis caused by OGD. Finally, we found that genetic deletion of the AMPKalpha1, but not AMPKalpha2, suppressed OGD-enhanced NF-kappaB activation, the expression of Bcl-2 and Survivin, and endothelial apoptosis. Overall, our results suggest that AMPKalpha1, but not AMPKalpha2 activation, promotes cell survival by increasing NF-kappaB-mediated expression of anti-apoptotic proteins (Bcl-2 and Survivin) and intracellular ATP contents.
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Affiliation(s)
- Chao Liu
- Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104; Department of Pharmacology, Xianning College, Hubei 437000, China
| | - Bin Liang
- Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Qilong Wang
- Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jiliang Wu
- Department of Pharmacology, Xianning College, Hubei 437000, China
| | - Ming-Hui Zou
- Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
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Dong Y, Zhang M, Liang B, Xie Z, Zhao Z, Asfa S, Choi HC, Zou MH. Reduction of AMP-activated protein kinase alpha2 increases endoplasmic reticulum stress and atherosclerosis in vivo. Circulation 2010; 121:792-803. [PMID: 20124121 DOI: 10.1161/circulationaha.109.900928] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Aberrant endoplasmic reticulum (ER) stress is associated with several cardiovascular diseases, including atherosclerosis. The mechanism by which aberrant ER stress develops is poorly understood. This study investigated whether dysfunction of AMP-activated protein kinase (AMPK) causes aberrant ER stress and atherosclerosis in vivo. METHODS AND RESULTS Human umbilical vein endothelial cells and mouse aortic endothelial cells from AMPK-deficient mice were used to assess the level of ER stress with Western blotting. Reduction of AMPKalpha2 expression significantly increased the level of ER stress in human umbilical vein endothelial cells. In addition, mouse aortic endothelial cells from AMPKalpha2 knockout (AMPKalpha2(-/-)) mice had higher expression of markers of ER stress and increased levels of intracellular Ca2+. These phenotypes were abolished by adenovirally overexpressing constitutively active AMPK mutants (Ad-AMPK-CA) or by transfecting sarcoendoplasmic reticulum calcium ATPase (SERCA). Inhibition of SERCA induced ER stress in endothelial cells. Furthermore, reduction of AMPKalpha expression suppressed SERCA activity. In addition, SERCA activity was significantly reduced concomitantly with increased oxidation of SERCA in mouse aortic endothelial cells from AMPKalpha2(-/-) mice. Both of these phenotypes were abolished by adenovirally overexpressing Ad-AMPK-CA. Furthermore, Tempol, which restored SERCA activity and decreased oxidized SERCA levels, markedly reduced the level of ER stress in mouse aortic endothelial cells from AMPKalpha2(-/-) mice. Finally, oral administration of tauroursodeoxycholic acid, a chemical chaperone that inhibits ER stress, significantly reduced both ER stress and aortic lesion development in low-density lipoprotein receptor- and AMPKalpha2-deficient mice. CONCLUSIONS These results suggest that AMPK functions as a physiological suppressor of ER stress by maintaining SERCA activity and intracellular Ca2+ homeostasis.
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Affiliation(s)
- Yunzhou Dong
- Department of Medicine and Endocrinology, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
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60
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61
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Affiliation(s)
- Jian Xu
- Department of Medicine and Endocrinology, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
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62
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Li XN, Song J, Zhang L, LeMaire SA, Hou X, Zhang C, Coselli JS, Chen L, Wang XL, Zhang Y, Shen YH. Activation of the AMPK-FOXO3 pathway reduces fatty acid-induced increase in intracellular reactive oxygen species by upregulating thioredoxin. Diabetes 2009; 58:2246-57. [PMID: 19592618 PMCID: PMC2750236 DOI: 10.2337/db08-1512] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
OBJECTIVE Oxidative stress induced by free fatty acids contributes to the development of cardiovascular diseases in patients with metabolic syndrome. Reducing oxidative stress may attenuate these pathogenic processes. Activation of AMP-activated protein kinase (AMPK) has been reported to reduce intracellular reactive oxygen species (ROS) levels. The thioredoxin (Trx) system is a major antioxidant system. In this study, we investigated the mechanisms involved in the AMPK-mediated regulation of Trx expression and the reduction of intracellular ROS levels. RESEARCH DESIGN AND METHODS We observed that activation of AMPK by 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) significantly reduced ROS levels induced by palmitic acid in human aortic endothelial cells. Activation of AMPK increased expression of the antioxidant Trx, which mediated the ROS reduction. RT-PCR showed that AMPK regulated Trx at the transcriptional level. RESULTS Forkhead transcription factor 3 (FOXO3) was identified as the target transcription factor involved in the upregulation of Trx expression. FOXO3 bound to the Trx promoter, recruited the histone acetylase p300 to the Trx promoter, and formed a transcription activator complex, which was enhanced by AICAR treatment. AMPK activated FOXO3 by promoting its nuclear translocation. We further showed that AICAR injection increased the expression of Trx and decreased ROS production in the aortic wall of ApoE-/- mice fed a high-fat diet. CONCLUSIONS These results suggest that activation of the AMPK-FOXO3 pathway reduces ROS levels by inducing Trx expression. Thus, the AMPK-FOXO3-Trx axis may be an important defense mechanism against excessive ROS production induced by metabolic stress and could be a therapeutic target in treating cardiovascular diseases in metabolic syndrome.
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Affiliation(s)
- Xiao-Nan Li
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
- Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Jun Song
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
- Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Lin Zhang
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
| | - Scott A. LeMaire
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
| | - Xiaoyang Hou
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
- Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Cheng Zhang
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
- Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Joseph S. Coselli
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
| | - Li Chen
- Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Xing Li Wang
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
| | - Yun Zhang
- Qilu Hospital, Shandong University, Jinan, Shandong, China
- Corresponding authors: Yun Zhang, , and Ying H. Shen,
| | - Ying H. Shen
- Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
- Corresponding authors: Yun Zhang, , and Ying H. Shen,
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Endothelial nitric oxide synthase negatively regulates hydrogen peroxide-stimulated AMP-activated protein kinase in endothelial cells. Proc Natl Acad Sci U S A 2009; 106:17343-8. [PMID: 19805165 DOI: 10.1073/pnas.0907409106] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Hydrogen peroxide and other reactive oxygen species are intimately involved in endothelial cell signaling. In many cell types, the AMP-activated protein kinase (AMPK) has been implicated in the control of metabolic responses, but the role of endothelial cell redox signaling in the modulation of AMPK remains to be completely defined. We used RNA interference and pharmacological methods to establish that H(2)O(2) is a critical activator of AMPK in cultured bovine aortic endothelial cells (BAECs). H(2)O(2) treatment of BAECs rapidly and significantly increases the phosphorylation of AMPK. The EC(50) for H(2)O(2)-promoted phosphorylation of AMPK is 65 + or - 15 microM, within the physiological range of cellular H(2)O(2) concentrations. The Ca(2+)/calmodulin-dependent protein kinase kinase-beta (CaMKKbeta) inhibitor STO-609 abolishes H(2)O(2)-dependent AMPK activation, whereas eNOS inhibitors enhance AMPK activation. Similarly, siRNA-mediated knockdown of CaMKKbeta abrogates AMPK activation, whereas siRNA-mediated knockdown of eNOS leads to a striking increase in AMPK phosphorylation. Cellular imaging studies using the H(2)O(2) biosensor HyPer show that siRNA-mediated eNOS knockdown leads to a marked increase in intracellular H(2)O(2) generation, which is blocked by PEG-catalase. eNOS(-/-) mice show a marked increase in AMPK phosphorylation in liver and lung compared to wild-type mice. Lung endothelial cells from eNOS(-/-) mice also show a significant increase in AMPK phosphorylation. Taken together, these results establish that CaMKKbeta is critically involved in mediating the phosphorylation of AMPK promoted by H(2)O(2) in endothelial cells, and document that eNOS is an important negative regulator of AMPK phosphorylation and intracellular H(2)O(2) generation in endothelial cells.
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Song P, Zhang M, Wang S, Xu J, Choi HC, Zou MH. Thromboxane A2 receptor activates a Rho-associated kinase/LKB1/PTEN pathway to attenuate endothelium insulin signaling. J Biol Chem 2009; 284:17120-17128. [PMID: 19403525 DOI: 10.1074/jbc.m109.012583] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
This study was conducted to elucidate the molecular mechanisms of thromboxane A2 receptor (TP)-induced insulin resistance in endothelial cells. Exposure of human umbilical vein endothelial cells (HUVECs) or mouse aortic endothelial cells to either IBOP or U46619, two structurally related thromboxane A(2) mimetics, significantly reduced insulin-stimulated phosphorylation of endothelial nitric-oxide synthase (eNOS) at Ser(1177) and Akt at Ser(473). These effects were abolished by pharmacological or genetic inhibitors of TP. TP-induced suppression of both eNOS and Akt phosphorylation was accompanied by up-regulation of PTEN (phosphatase and tension homolog deleted on chromosome 10), Ser(380)/Thr(382/383) PTEN phosphorylation, and PTEN lipid phosphatase activity. PTEN-specific small interference RNA restored insulin signaling in the face of TP activation. The small GTPase, Rho, was also activated by TP stimulation, and pretreatment of HUVECs with Y27632, a Rho-associated kinase inhibitor, rescued TP-impaired insulin signaling. Consistent with this result, pertussis toxin abrogated IBOP-induced dephosphorylation of both Akt and eNOS, implicating the G(i) family of G proteins in the suppressive effects of TP. In mice, high fat diet-induced diabetes was associated with aortic PTEN up-regulation, PTEN-Ser(380)/Thr(382/383) phosphorylation, and dephosphorylation of both Akt (at Ser(473)) and eNOS (at Ser(1177)). Importantly, administration of TP antagonist blocked these changes. We conclude that TP stimulation impairs insulin signaling in vascular endothelial cells by selectively activating the Rho/Rho-associated kinase/LKB1/PTEN pathway.
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Affiliation(s)
- Ping Song
- From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Miao Zhang
- From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Shuangxi Wang
- From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jian Xu
- From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Hyoung Chul Choi
- From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Ming-Hui Zou
- From the Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
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Wilson SJ, Cavanagh CC, Lesher AM, Frey AJ, Russell SE, Smyth EM. Activation-dependent stabilization of the human thromboxane receptor: role of reactive oxygen species. J Lipid Res 2009; 50:1047-56. [PMID: 19151335 DOI: 10.1194/jlr.m800447-jlr200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thromboxane A(2) (TxA(2)), the principle product of platelet COX-1-dependent arachidonic acid metabolism, directs multiple pro-atherogenic processes via its receptor, TP. Oxidative challenge offsets TP degradation, a key component in limiting TxA(2)'s actions. Following TP activation, we observed cellular reactive oxygen species (ROS) generation coincident with increased TP expression. We examined the link between TP-evoked ROS and TP regulation. TP expression was augmented in TPalpha-transfected cells treated with a TxA(2) analog [1S-1alpha,2beta(5Z),3alpha(1E,3R*),4alpha]]-7-[3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo-[2.2.1]heptan-2-yl]-5-heptenoic acid (IBOP). This was reduced with a cellular antioxidant, N-acetyl cysteine, or two distinct NADPH oxidase inhibitors, diphenyleneiodonium and apocynin. Homologous upregulation of the native TP was also reduced in apocynin-treated aortic smooth muscle cells (ASMCs) and was absent in ASMCs lacking an NADPH oxidase subunit (p47(-/-)). TP transcription was not increased in IBOP-treated cells, indicating a posttranscriptional mechanism. IBOP induced translocation of TPalpha to the Golgi and reduced degradation of the immature form of the receptor. These data are consistent with a ROS-dependent mechanism whereby TP activation enhanced TP stability early in posttranscriptional biogenesis. Given the significant role played by TP and ROS in perturbed cardiovascular function, the convergence of TP on ROS-generating pathways for regulation of TxA(2)-dependent events may be critical for cardiovascular disease.
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Affiliation(s)
- Stephen J Wilson
- Institute of Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
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Hutchinson DS, Summers RJ, Bengtsson T. Regulation of AMP-activated protein kinase activity by G-protein coupled receptors: Potential utility in treatment of diabetes and heart disease. Pharmacol Ther 2008; 119:291-310. [DOI: 10.1016/j.pharmthera.2008.05.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 05/27/2008] [Indexed: 12/25/2022]
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Hu Z, Chen J, Wei Q, Xia Y. Bidirectional actions of hydrogen peroxide on endothelial nitric-oxide synthase phosphorylation and function: co-commitment and interplay of Akt and AMPK. J Biol Chem 2008; 283:25256-25263. [PMID: 18617528 DOI: 10.1074/jbc.m802455200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Endothelial NO synthase (eNOS) is critically modulated by kinases via the phosphorylation of its Ser(1179) (bovine) or Ser(1177) (human) residue. Reactive oxygen species such as H(2)O(2) was reported to activate Akt, leading to increased eNOS Ser(1179) phosphorylation and activity. But reactive oxygen species are also known to attenuate eNOS function in cardiovascular diseases. Prior studies showing H(2)O(2)-stimulated eNOS phosphorylation were performed on serum-starved cells, and only the short term effect of H(2)O(2) was examined. Here we found that the effects of H(2)O(2) on eNOS Ser(1179) phosphorylation and function were bidirectional. With endothelial cells cultured with serum, H(2)O(2) initially raised eNOS Ser(1179) phosphorylation and activity. However, after the peak increase at 30 min, eNOS Ser(1179) phosphorylation dramatically declined. Parallel to the alterations of eNOS Ser(1179) phosphorylation, Akt was transiently activated by H(2)O(2) and subsequently became dormant. In contrast, AMP-activated protein kinase (AMPK) was progressively activated in H(2)O(2)-treated cells. Blocking Akt activation abolished the initial rise of eNOS Ser(1179) phosphorylation after H(2)O(2) treatment. In long term H(2)O(2)-treated cells where Akt was deactivated, significant amounts of Ser(1179)-phosphorylated eNOS remained. AMPK inhibition eradicated the remaining eNOS Ser(1179) phosphorylation. Taken together, these studies revealed that Akt and AMPK orchestrated a bidirectional action on eNOS Ser(1179) phosphorylation in H(2)O(2)-treated cells. Long term H(2)O(2) exposure decreased eNOS Ser(1179) phosphorylation, and this might account for the loss of eNOS function in cardiovascular diseases where chronic oxidative injury occurs.
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Affiliation(s)
- Zhuangli Hu
- Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Molecular and Cellular Biochemistry, The Ohio State University Medical Center, Columbus, Ohio 43210
| | - Juan Chen
- Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Molecular and Cellular Biochemistry, The Ohio State University Medical Center, Columbus, Ohio 43210
| | - Qin Wei
- Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Molecular and Cellular Biochemistry, The Ohio State University Medical Center, Columbus, Ohio 43210
| | - Yong Xia
- Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Molecular and Cellular Biochemistry, The Ohio State University Medical Center, Columbus, Ohio 43210.
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Dong Y, Wu Y, Wu M, Wang S, Zhang J, Xie Z, Xu J, Song P, Wilson K, Zhao Z, Lyons T, Zou MH. Activation of protease calpain by oxidized and glycated LDL increases the degradation of endothelial nitric oxide synthase. J Cell Mol Med 2008; 13:2899-910. [PMID: 18624772 PMCID: PMC2821526 DOI: 10.1111/j.1582-4934.2008.00416.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Oxidation and glycation of low-density lipoprotein (LDL) promote vascular injury in diabetes; however, the mechanisms underlying this effect remain poorly defined. The present study was conducted to determine the effects of ‘heavily oxidized’ glycated LDL (HOG-LDL) on endothelial nitric oxide synthase (eNOS) function. Exposure of bovine aortic endothelial cells with HOG-LDL reduced eNOS protein levels in a concentration- and time-dependent manner, without altering eNOS mRNA levels. Reduced eNOS protein levels were accompanied by an increase in intracellular Ca2+, augmented production of reactive oxygen species (ROS) and induction of Ca2+-dependent calpain activity. Neither eNOS reduction nor any of these other effects were observed in cells exposed to native LDL. Reduction of intracellular Ca2+ levels abolished eNOS reduction by HOG-LDL, as did pharmacological or genetic through calcium channel blockers or calcium chelator BAPTA or inhibition of NAD(P)H oxidase (with apocynin) or inhibition of calpain (calpain 1-specific siRNA). Consistent with these results, HOG-LDL impaired acetylcholine-induced endothelium-dependent vasorelaxation of isolated mouse aortas, and pharmacological inhibition of calpain prevented this effect. HOG-LDL may impair endothelial function by inducing calpain-mediated eNOS degradation in a ROS- and Ca2+-dependent manner.
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Affiliation(s)
- Yunzhou Dong
- Harold Hamm Oklahoma Diabetes Center, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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