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Pálóczi J, Paál Á, Pigler J, Kiss B, Rhoden A, Varga ZV, Ferdinandy P, Eschenhagen T, Görbe A. Organ-specific model of simulated ischemia/reperfusion and hyperglycemia based on engineered heart tissue. Vascul Pharmacol 2023; 152:107208. [PMID: 37572973 DOI: 10.1016/j.vph.2023.107208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 08/03/2023] [Accepted: 08/10/2023] [Indexed: 08/14/2023]
Abstract
Here we aimed to establish an in vitro engineered heart tissue (EHT) co-morbidity mimicking model of ischemia-reperfusion injury and diabetes. EHTs were generated from primary neonatal rat cardiomyocytes. Hyperglycemic conditions or hyperosmolar controls were applied for one day to model acute hyperglycemia and for seven days to model chronic hyperglycemia. 120 min' simulated ischemia (SI) was followed by 120 min' reperfusion (R) and 1-day follow-up reperfusion (FR). Normoxic controls (N) were not subjected to SI/R. Half of the EHTs was paced, the other half was left unpaced. To assess cell injury, lactate-dehydrogenase (LDH) concentration was measured. Beating force and activity (frequency) were monitored as cardiomyocyte functional parameters. LDH-release indicated relevant cell injury after SI/N in each experimental condition, with much higher effects in the chronically hyperglycemic/hyperosmolar groups. SI stopped beating of EHTs in each condition, which returned during reperfusion, with weaker recovery in chronic conditions than in acute conditions. Acutely treated EHTs showed small LDH-release and ∼80% recovery of force during reperfusion and follow-up, while chronically treated EHTs showed a marked LDH-release, only ∼30% recovery with reperfusion and complete loss of beating activity during 24 h follow-up reperfusion. We conclude that EHTs respond differently to SI/R injury in acute and chronic hyperglycemia/hyperosmolarity, and that our EHT model is a novel in vitro combination of diabetes and ischemia-reperfusion.
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Affiliation(s)
- J Pálóczi
- Cardiovascular Research Group, Department of Biochemistry, University of Szeged, Szeged H-6720, Hungary; Pharmahungary Group, Szeged H-6722, Hungary
| | - Á Paál
- MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest H-1089, Hungary
| | - J Pigler
- Cardiovascular Research Group, Department of Biochemistry, University of Szeged, Szeged H-6720, Hungary
| | - B Kiss
- MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest H-1089, Hungary
| | - A Rhoden
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, DZHK (German Centre for Cardiovascular Research) Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany; DiNAQOR Deutschland GmbH, Start-up Labs Bahrenfeld, Luruper Hauptstrasse 1, Hamburg 22547, Germany
| | - Z V Varga
- MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest H-1089, Hungary
| | - P Ferdinandy
- MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest H-1089, Hungary; Pharmahungary Group, Szeged H-6722, Hungary
| | - T Eschenhagen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, DZHK (German Centre for Cardiovascular Research) Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - A Görbe
- MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest H-1089, Hungary; Pharmahungary Group, Szeged H-6722, Hungary.
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Xia Y, Xu X, Guo Y, Lin C, Xu X, Zhang F, Fan M, Qi T, Li C, Hu G, Peng L, Wang S, Zhang L, Hai C, Liu R, Yan W, Tao L. Mesenchymal Stromal Cells Overexpressing Farnesoid X Receptor Exert Cardioprotective Effects Against Acute Ischemic Heart Injury by Binding Endogenous Bile Acids. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200431. [PMID: 35780502 PMCID: PMC9404394 DOI: 10.1002/advs.202200431] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 05/14/2022] [Indexed: 06/15/2023]
Abstract
Bile acid metabolites have been increasingly recognized as pleiotropic signaling molecules that regulate cardiovascular functions, but their role in mesenchymal stromal cells (MSC)-based therapy has never been investigated. It is found that overexpression of farnesoid X receptor (FXR), a main receptor for bile acids, improves the retention and cardioprotection of adipose tissue-derived MSC (ADSC) administered by intramyocardial injection in mice with myocardial infarction (MI), which shows enhanced antiapoptotic, proangiogenic, and antifibrotic effects. RNA sequencing, LC-MS/MS, and loss-of-function studies reveal that FXR overexpression promotes ADSC paracrine angiogenesis via Angptl4. FXR overexpression improves ADSC survival in vivo but fails in vitro. By performing bile acid-targeted metabolomics using ischemic heart tissue, 19 bile acids are identified. Among them, cholic acid and deoxycholic acid significantly increase Angptl4 secretion from ADSC overexpressing FXR and further improve their proangiogenic capability. Moreover, ADSC overexpressing FXR shows significantly lower apoptosis by upregulating Nqo-1 expression only in the presence of FXR ligands. Retinoid X receptor α is identified as a coactivator of FXR. It is first demonstrated that there is a bile acid pool in the myocardial microenvironment. Targeting the bile acid-FXR axis may be a novel strategy for improving the curative effect of MSC-based therapy for MI.
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Affiliation(s)
- Yunlong Xia
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Xinyue Xu
- State Key Laboratory of Military StomatologyNational Clinical Research Center for Oral Diseases and Shaanxi Engineering Research Center for Dental Materials and Advanced ManufactureDepartment of PeriodontologySchool of StomatologyFourth Military Medical UniversityXi'anShaanxi710032China
| | - Yongzhen Guo
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Chen Lin
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
- CardiologyGeneral Hospital of Eastern Theater Command of Chinese PLANanjing210002China
| | - Xiaoming Xu
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Fuyang Zhang
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Miaomiao Fan
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Tingting Qi
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Congye Li
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Guangyu Hu
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Lu Peng
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Shan Wang
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Ling Zhang
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Chunxu Hai
- Department of ToxicologyShanxi Provincial Key Lab of Free Radical Biology and MedicineMinistry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anShaanxi710032P. R. China
| | - Rui Liu
- Department of ToxicologyShanxi Provincial Key Lab of Free Radical Biology and MedicineMinistry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anShaanxi710032P. R. China
| | - Wenjun Yan
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
| | - Ling Tao
- CardiologyXijing HospitalFourth Military Medical UniversityXi'an710032China
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Yi-Dan H, Ying-Xin Z, Shi-Wei Y, Yu-Jie Z. High-Energy Phosphates and Ischemic Heart Disease: From Bench to Bedside. Front Cardiovasc Med 2021; 8:675608. [PMID: 34395552 PMCID: PMC8355518 DOI: 10.3389/fcvm.2021.675608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 06/17/2021] [Indexed: 12/28/2022] Open
Abstract
The purpose of this review is to bridge the gap between clinical and basic research through providing a comprehensive and concise description of the cellular and molecular aspects of cardioprotective mechanisms and a critical evaluation of the clinical evidence of high-energy phosphates (HEPs) in ischemic heart disease (IHD). According to the well-documented physiological, pathophysiological and pharmacological properties of HEPs, exogenous creatine phosphate (CrP) may be considered as an ideal metabolic regulator. It plays cardioprotection roles from upstream to downstream of myocardial ischemia through multiple complex mechanisms, including but not limited to replenishment of cellular energy. Although exogenous CrP administration has not been shown to improve long-term survival, the beneficial effects on multiple secondary but important outcomes and short-term survival are concordant with its pathophysiological and pharmacological effects. There is urgent need for high-quality multicentre RCTs to confirm long-term survival improvement in the future.
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Affiliation(s)
- Hao Yi-Dan
- The Key Laboratory of Remodeling-Related Cardiovascular Disease, Ministry of Education, Beijing Institute of Heart, Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhao Ying-Xin
- The Key Laboratory of Remodeling-Related Cardiovascular Disease, Ministry of Education, Beijing Institute of Heart, Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yang Shi-Wei
- The Key Laboratory of Remodeling-Related Cardiovascular Disease, Ministry of Education, Beijing Institute of Heart, Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhou Yu-Jie
- The Key Laboratory of Remodeling-Related Cardiovascular Disease, Ministry of Education, Beijing Institute of Heart, Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
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Yes-Associated Protein (Yap) Is Up-Regulated in Heart Failure and Promotes Cardiac Fibroblast Proliferation. Int J Mol Sci 2021; 22:ijms22116164. [PMID: 34200497 PMCID: PMC8201133 DOI: 10.3390/ijms22116164] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 01/01/2023] Open
Abstract
Left ventricular (LV) heart failure (HF) is a significant and increasing cause of death worldwide. HF is characterized by myocardial remodeling and excessive fibrosis. Transcriptional co-activator Yes-associated protein (Yap), the downstream effector of HIPPO signaling pathway, is an essential factor in cardiomyocyte survival; however, its status in human LV HF is not entirely elucidated. Here, we report that Yap is elevated in LV tissue of patients with HF, and is associated with down-regulation of its upstream inhibitor HIPPO component large tumor suppressor 1 (LATS1) activation as well as upregulation of the fibrosis marker connective tissue growth factor (CTGF). Applying the established profibrotic combined stress of TGFβ and hypoxia to human ventricular cardiac fibroblasts in vitro increased Yap protein levels, down-regulated LATS1 activation, increased cell proliferation and collagen I production, and decreased ribosomal protein S6 and S6 kinase phosphorylation, a hallmark of mTOR activation, without any significant effect on mTOR and raptor protein expression or phosphorylation of mTOR or 4E-binding protein 1 (4EBP1), a downstream effector of mTOR pathway. As previously reported in various cell types, TGFβ/hypoxia also enhanced cardiac fibroblast Akt and ERK1/2 phosphorylation, which was similar to our observation in LV tissues from HF patients. Further, depletion of Yap reduced TGFβ/hypoxia-induced cardiac fibroblast proliferation and Akt phosphorylation at Ser 473 and Thr308, without any significant effect on TGFβ/hypoxia-induced ERK1/2 activation or reduction in S6 and S6 kinase activities. Taken together, these data demonstrate that Yap is a mediator that promotes human cardiac fibroblast proliferation and suggest its possible contribution to remodeling of the LV, opening the door to further studies to decipher the cell-specific roles of Yap signaling in human HF.
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Zhou G, Zha XM. GPR68 Contributes to Persistent Acidosis-Induced Activation of AGC Kinases and Tyrosine Phosphorylation in Organotypic Hippocampal Slices. Front Neurosci 2021; 15:692217. [PMID: 34113235 PMCID: PMC8185064 DOI: 10.3389/fnins.2021.692217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 04/29/2021] [Indexed: 12/28/2022] Open
Abstract
Persistent acidosis occurs in ischemia and multiple neurological diseases. In previous studies, acidic stimulation leads to rapid increase in intracellular calcium in neurons. However, it remains largely unclear how a prolonged acidosis alters neuronal signaling. In our previous study, we found that GPR68-mediated PKC activities are protective against acidosis-induced injury in cortical slices. Here, we first asked whether the same principle holds true in organotypic hippocampal slices. Our data showed that 1-h pH 6 induced PKC phosphorylation in a GPR68-dependent manner. Go6983, a PKC inhibitor worsened acidosis-induced neuronal injury in wild type (WT) but had no effect in GPR68−/− slices. Next, to gain greater insights into acid signaling in brain tissue, we treated organotypic hippocampal slices with pH 6 for 1-h and performed a kinome profiling analysis by Western blot. Acidosis had little effect on cyclin-dependent kinase (CDK) or casein kinase 2 activity, two members of the CMGC family, or Ataxia telangiectasia mutated (ATM)/ATM and RAD3-related (ATR) activity, but reduced the phosphorylation of MAPK/CDK substrates. In contrast, acidosis induced the activation of CaMKIIα, PKA, and Akt. Besides these serine/threonine kinases, acidosis also induced tyrosine phosphorylation. Since GPR68 is widely expressed in brain neurons, we asked whether GPR68 contributes to acidosis-induced signaling. Deleting GPR68 had no effect on acidosis-induced CaMKII phosphorylation, attenuated that of phospho-Akt and phospho-PKA substrates, while abolishing acidosis-induced tyrosine phosphorylation. These data demonstrate that prolonged acidosis activates a network of signaling cascades, mediated by AGC kinases, CaMKII, and tyrosine kinases. GPR68 is the primary mediator for acidosis-induced activation of PKC and tyrosine phosphorylation, while both GPR68-dependent and -independent mechanisms contribute to the activation of PKA and Akt.
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Affiliation(s)
- Guokun Zhou
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Xiang-Ming Zha
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, AL, United States
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Tsg101 Is Involved in the Sorting and Re-Distribution of Glucose Transporter-4 to the Sarcolemma Membrane of Cardiac Myocytes. Cells 2020; 9:cells9091936. [PMID: 32839388 PMCID: PMC7565110 DOI: 10.3390/cells9091936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/07/2020] [Accepted: 08/18/2020] [Indexed: 11/17/2022] Open
Abstract
Cardiac cells can adapt to pathological stress-induced energy crisis by shifting from fatty acid oxidation to glycolysis. However, the use of glucose-insulin-potassium (GIK) solution in patients undergoing cardiac surgery does not alleviate ischemia/reperfusion (I/R)-induced energy shortage. This indicates that insulin-mediated translocation of glucose transporter-4 (Glut-4) is impaired in ischemic hearts. Indeed, cardiac myocytes contain two intracellular populations of Glut-4: an insulin-dependent non-endosomal pool (also referred to as Glut-4 storage vesicles, GSVs) and an insulin-independent endosomal pool. Tumor susceptibility gene 101 (Tsg101) has been implicated in the endosomal recycling of membrane proteins. In this study, we aimed to examine whether Tsg101 regulated the sorting and re-distribution of Glut-4 to the sarcolemma membrane of cardiomyocytes under basal and ischemic conditions, using gain- and loss-of-function approaches. Forced overexpression of Tsg101 in mouse hearts and isolated cardiomyocytes could promote Glut-4 re-distribution to the sarcolemma, leading to enhanced glucose entry and adenosine triphosphate (ATP) generation in I/R hearts which in turn, attenuation of I/R-induced cardiac dysfunction. Conversely, knockdown of Tsg101 in cardiac myocytes exhibited opposite effects. Mechanistically, we identified that Tsg101 could interact and co-localize with Glut-4 in the sarcolemma membrane of cardiomyocytes. Our findings define Tsg101 as a novel regulator of cardiac Glut-4 trafficking, which may provide a new therapeutic strategy for the treatment of ischemic heart disease.
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Heliste J, Jokilammi A, Paatero I, Chakroborty D, Stark C, Savunen T, Laaksonen M, Elenius K. Receptor tyrosine kinase profiling of ischemic heart identifies ROR1 as a potential therapeutic target. BMC Cardiovasc Disord 2018; 18:196. [PMID: 30342492 PMCID: PMC6196006 DOI: 10.1186/s12872-018-0933-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/08/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Receptor tyrosine kinases (RTK) are potential targets for the treatment of ischemic heart disease. The human RTK family consists of 55 members, most of which have not yet been characterized for expression or activity in the ischemic heart. METHODS RTK gene expression was analyzed from human heart samples representing healthy tissue, acute myocardial infarction or ischemic cardiomyopathy. As an experimental model, pig heart with ischemia-reperfusion injury, caused by cardiopulmonary bypass, was used, from which phosphorylation status of RTKs was assessed with a phospho-RTK array. Expression and function of one RTK, ROR1, was further validated in pig tissue samples, and in HL-1 cardiomyocytes and H9c2 cardiomyoblasts, exposed to hypoxia and reoxygenation. ROR1 protein level was analyzed by Western blotting. Cell viability after ROR1 siRNA knockdown or activation with Wnt-5a ligand was assessed by MTT assays. RESULTS In addition to previously characterized RTKs, a group of novel active and regulated RTKs was detected in the ischemic heart. ROR1 was the most significantly upregulated RTK in human ischemic cardiomyopathy. However, ROR1 phosphorylation was suppressed in the pig model of ischemia-reperfusion and ROR1 phosphorylation and expression were down-regulated in HL-1 cardiomyocytes subjected to short-term hypoxia in vitro. ROR1 expression in the pig heart was confirmed on protein and mRNA level. Functionally, ROR1 activity was associated with reduced viability of HL-1 cardiomyocytes in both normoxia and during hypoxia-reoxygenation. CONCLUSIONS Several novel RTKs were found to be regulated in expression or activity in ischemic heart. ROR1 was one of the most significantly regulated RTKs. The in vitro findings suggest a role for ROR1 as a potential target for the treatment of ischemic heart injury.
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Affiliation(s)
- Juho Heliste
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland.,Turku Doctoral Programme of Molecular Medicine, University of Turku, Turku, Finland.,Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
| | - Anne Jokilammi
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland
| | - Ilkka Paatero
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland.,Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland
| | - Deepankar Chakroborty
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland.,Turku Doctoral Programme of Molecular Medicine, University of Turku, Turku, Finland
| | - Christoffer Stark
- Research Center of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
| | - Timo Savunen
- Research Center of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
| | | | - Klaus Elenius
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland. .,Medicity Research Laboratories, University of Turku, Turku, Finland. .,Department of Oncology, Turku University Hospital, Turku, Finland.
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8
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Liu X, Deng Y, Xu Y, Jin W, Li H. MicroRNA-223 protects neonatal rat cardiomyocytes and H9c2 cells from hypoxia-induced apoptosis and excessive autophagy via the Akt/mTOR pathway by targeting PARP-1. J Mol Cell Cardiol 2018; 118:133-146. [PMID: 29608885 DOI: 10.1016/j.yjmcc.2018.03.018] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 03/17/2018] [Accepted: 03/27/2018] [Indexed: 01/15/2023]
Abstract
Myocardial infarction (MI), characterized by interruption of blood and oxygen to myocardium, is a common yet fatal cardiovascular event that causes progressive damage to myocardial tissue and eventually leads to heart failure. Previous studies have shown increased expression of microRNA-223 (miR-223) in infarcted myocardial tissues of humans and in rat models of MI. However, the role of miR-223 in cell survival during MI has not been elucidated. Thus, we aimed to investigate whether miR-223 participates in the regulation of cardiac ischemia-induced injury and to elucidate the underlying mechanisms of this process. qRT-PCR revealed that miR-223 expression levels are significantly upregulated in the myocardial tissues of rats with post-MI heart failure and in hypoxia-treated neonatal rat cardiomyocytes (NRCMs) and H9c2 cells, which indicates that miR-223 may be associated with chronic ischemia. We also transfected NRCMs and H9c2 cells with miR-223 mimics or inhibitors in vitro, and the results revealed that increasing miR-223 expression protected cells from hypoxia-induced apoptosis and excessive autophagy, whereas decreasing miR-223 expression had contrasting effects. Further exploration of the mechanism showed that poly(ADP-ribose) polymerase 1 (PARP-1) is a target gene of miR-223 and that silencing PARP-1 prevented hypoxia-induced cell injury; additionally, silencing PARP-1 blocked the aggravated impact of miR-223 inhibitors. Thus, PARP-1 mediates the protective effects of miR-223 in hypoxia-treated cardiomyocytes. We also investigated the involvement of the Akt/mTOR pathway in the above phenomena. We found that miR-223 overexpression and PARP-1 silencing positively regulated the Akt/mTOR pathway and that treating cells with NVP-BEZ235 (BEZ235), a novel dual Akt/mTOR inhibitor, could reverse the inhibitory effects of both the miR-223 mimics and PARP-1 siRNA on hypoxia-induced apoptosis and autophagy. Taken together, our findings showed that miR-223 protects NRCMs and H9c2 cells from hypoxia-induced apoptosis and excessive autophagy via the Akt/mTOR pathway by targeting PARP-1; thus, miR-223 may be a potential target in the treatment of MI in the future.
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Affiliation(s)
- Xiaoxiao Liu
- Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yunfei Deng
- Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yifeng Xu
- Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wei Jin
- Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
| | - Hongli Li
- Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
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Mansor LS, Sousa Fialho MDL, Yea G, Coumans WA, West JA, Kerr M, Carr CA, Luiken JJFP, Glatz JFC, Evans RD, Griffin JL, Tyler DJ, Clarke K, Heather LC. Inhibition of sarcolemmal FAT/CD36 by sulfo-N-succinimidyl oleate rapidly corrects metabolism and restores function in the diabetic heart following hypoxia/reoxygenation. Cardiovasc Res 2018; 113:737-748. [PMID: 28419197 PMCID: PMC5437367 DOI: 10.1093/cvr/cvx045] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 03/23/2017] [Indexed: 11/14/2022] Open
Abstract
Aims The type 2 diabetic heart oxidizes more fat and less glucose, which can impair metabolic flexibility and function. Increased sarcolemmal fatty acid translocase (FAT/CD36) imports more fatty acid into the diabetic myocardium, feeding increased fatty acid oxidation and elevated lipid deposition. Unlike other metabolic modulators that target mitochondrial fatty acid oxidation, we proposed that pharmacologically inhibiting fatty acid uptake, as the primary step in the pathway, would provide an alternative mechanism to rebalance metabolism and prevent lipid accumulation following hypoxic stress. Methods and results Hearts from type 2 diabetic and control male Wistar rats were perfused in normoxia, hypoxia and reoxygenation, with the FAT/CD36 inhibitor sulfo-N-succinimidyl oleate (SSO) infused 4 min before hypoxia. SSO infusion into diabetic hearts decreased the fatty acid oxidation rate by 29% and myocardial triglyceride concentration by 48% compared with untreated diabetic hearts, restoring fatty acid metabolism to control levels following hypoxia-reoxygenation. SSO infusion increased the glycolytic rate by 46% in diabetic hearts during hypoxia, increased pyruvate dehydrogenase activity by 53% and decreased lactate efflux rate by 56% compared with untreated diabetic hearts during reoxygenation. In addition, SSO treatment of diabetic hearts increased intermediates within the second span of the Krebs cycle, namely fumarate, oxaloacetate, and the FAD total pool. The cardiac dysfunction in diabetic hearts following decreased oxygen availability was prevented by SSO-infusion prior to the hypoxic stress. Infusing SSO into diabetic hearts increased rate pressure product by 60% during hypoxia and by 32% following reoxygenation, restoring function to control levels. Conclusions Diabetic hearts have limited metabolic flexibility and cardiac dysfunction when stressed, which can be rapidly rectified by reducing fatty acid uptake with the FAT/CD36 inhibitor, SSO. This novel therapeutic approach not only reduces fat oxidation but also lipotoxicity, by targeting the primary step in the fatty acid metabolism pathway.
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Affiliation(s)
- Latt S Mansor
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Maria da Luz Sousa Fialho
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Georgina Yea
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Will A Coumans
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - James A West
- Department of Biochemistry, University of Cambridge, and MRC Human Nutrition Research, Cambridge, UK
| | - Matthew Kerr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Joost J F P Luiken
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Jan F C Glatz
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Julian L Griffin
- Department of Biochemistry, University of Cambridge, and MRC Human Nutrition Research, Cambridge, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
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Kanaporis G, Treinys R, Fischmeister R, Jurevičius J. Metabolic inhibition reduces cardiac L-type Ca2+ channel current due to acidification caused by ATP hydrolysis. PLoS One 2017; 12:e0184246. [PMID: 28859158 PMCID: PMC5578678 DOI: 10.1371/journal.pone.0184246] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 08/21/2017] [Indexed: 01/14/2023] Open
Abstract
Metabolic stress evoked by myocardial ischemia leads to impairment of cardiac excitation and contractility. We studied the mechanisms by which metabolic inhibition affects the activity of L-type Ca2+ channels (LTCCs) in frog ventricular myocytes. Metabolic inhibition induced by the protonophore FCCP (as well as by 2,4- dinitrophenol, sodium azide or antimycin A) resulted in a dose-dependent reduction of LTCC current (ICa,L) which was more pronounced during β-adrenergic stimulation with isoprenaline. ICa,L was still reduced by metabolic inhibition even in the presence of 3 mM intracellular ATP, or when the cell was dialysed with cAMP or ATP-γ-S to induce irreversible thiophosphorylation of LTCCs, indicating that reduction in ICa,L is not due to ATP depletion and/or reduced phosphorylation of the channels. However, the effect of metabolic inhibition on ICa,L was strongly attenuated when the mitochondrial F1F0-ATP-synthase was blocked by oligomycin or when the cells were dialysed with the non-hydrolysable ATP analogue AMP-PCP. Moreover, increasing the intracellular pH buffering capacity or intracellular dialysis of the myocytes with an alkaline solution strongly attenuated the inhibitory effect of FCCP on ICa,L. Thus, our data demonstrate that metabolic inhibition leads to excessive ATP hydrolysis by the mitochondrial F1F0-ATP-synthase operating in the reverse mode and this results in intracellular acidosis causing the suppression of ICa,L. Limiting ATP break-down by F1F0-ATP-synthase and the consecutive development of intracellular acidosis might thus represent a potential therapeutic approach for maintaining a normal cardiac function during ischemia.
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Affiliation(s)
- Giedrius Kanaporis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Rimantas Treinys
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Rodolphe Fischmeister
- INSERM UMR-S 1180, Univ Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Jonas Jurevičius
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
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11
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Renguet E, Ginion A, Gélinas R, Bultot L, Auquier J, Robillard Frayne I, Daneault C, Vanoverschelde JL, Des Rosiers C, Hue L, Horman S, Beauloye C, Bertrand L. Metabolism and acetylation contribute to leucine-mediated inhibition of cardiac glucose uptake. Am J Physiol Heart Circ Physiol 2017. [PMID: 28646031 DOI: 10.1152/ajpheart.00738.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High plasma leucine levels strongly correlate with type 2 diabetes. Studies of muscle cells have suggested that leucine alters the insulin response for glucose transport by activating an insulin-negative feedback loop driven by the mammalian target of rapamycin/p70 ribosomal S6 kinase (mTOR/p70S6K) pathway. Here, we examined the molecular mechanism involved in leucine's action on cardiac glucose uptake. Leucine was indeed able to curb glucose uptake after insulin stimulation in both cultured cardiomyocytes and perfused hearts. Although leucine activated mTOR/p70S6K, the mTOR inhibitor rapamycin did not prevent leucine's inhibitory action on glucose uptake, ruling out the contribution of the insulin-negative feedback loop. α-Ketoisocaproate, the first metabolite of leucine catabolism, mimicked leucine's effect on glucose uptake. Incubation of cardiomyocytes with [13C]leucine ascertained its metabolism to ketone bodies (KBs), which had a similar negative impact on insulin-stimulated glucose transport. Both leucine and KBs reduced glucose uptake by affecting translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Finally, we found that leucine elevated the global protein acetylation level. Pharmacological inhibition of lysine acetyltransferases counteracted this increase in protein acetylation and prevented leucine's inhibitory action on both glucose uptake and GLUT4 translocation. Taken together, these results indicate that leucine metabolism into KBs contributes to inhibition of cardiac glucose uptake by hampering the translocation of GLUT4-containing vesicles via acetylation. They offer new insights into the establishment of insulin resistance in the heart.NEW & NOTEWORTHY Catabolism of the branched-chain amino acid leucine into ketone bodies efficiently inhibits cardiac glucose uptake through decreased translocation of glucose transporter 4 to the plasma membrane. Leucine increases protein acetylation. Pharmacological inhibition of acetylation reverses leucine's action, suggesting acetylation involvement in this phenomenon.Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/leucine-metabolism-inhibits-cardiac-glucose-uptake/.
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Affiliation(s)
- Edith Renguet
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium
| | - Audrey Ginion
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium
| | - Roselle Gélinas
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium
| | - Laurent Bultot
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium
| | - Julien Auquier
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium
| | | | | | - Jean-Louis Vanoverschelde
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium.,Cliniques Universitaires Saint-Luc, Division of Cardiology, Brussels, Belgium
| | - Christine Des Rosiers
- Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada; and
| | - Louis Hue
- Université catholique de Louvain, de Duve Institute, Brussels, Belgium
| | - Sandrine Horman
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium
| | - Christophe Beauloye
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium.,Cliniques Universitaires Saint-Luc, Division of Cardiology, Brussels, Belgium
| | - Luc Bertrand
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Cardiovascular Research, Brussels, Belgium;
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12
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Fenofibrate Therapy Restores Antioxidant Protection and Improves Myocardial Insulin Resistance in a Rat Model of Metabolic Syndrome and Myocardial Ischemia: The Role of Angiotensin II. Molecules 2016; 22:molecules22010031. [PMID: 28036029 PMCID: PMC6155612 DOI: 10.3390/molecules22010031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/04/2016] [Accepted: 12/20/2016] [Indexed: 11/25/2022] Open
Abstract
Renin-angiotensin system (RAS) activation promotes oxidative stress which increases the risk of cardiac dysfunction in metabolic syndrome (MetS) and favors local insulin resistance. Fibrates regulate RAS improving MetS, type-2 diabetes and cardiovascular diseases. We studied the effect of fenofibrate treatment on the myocardic signaling pathway of Angiotensin II (Ang II)/Angiotensin II type 1 receptor (AT1) and its relationship with oxidative stress and myocardial insulin resistance in MetS rats under heart ischemia. Control and MetS rats were assigned to the following groups: (a) sham; (b) vehicle-treated myocardial infarction (MI) (MI-V); and (c) fenofibrate-treated myocardial infarction (MI-F). Treatment with fenofibrate significantly reduced triglycerides, non-high density lipoprotein cholesterol (non-HDL-C), insulin levels and insulin resistance index (HOMA-IR) in MetS animals. MetS and MI increased Ang II concentration and AT1 expression, favored myocardial oxidative stress (high levels of malondialdehyde, overexpression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), decreased total antioxidant capacity and diminished expression of superoxide dismutase (SOD)1, SOD2 and catalase) and inhibited expression of the insulin signaling cascade: phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PkB, also known as Akt)/Glut-4/endothelial nitric oxide synthase (eNOS). In conclusion, fenofibrate treatment favors an antioxidant environment as a consequence of a reduction of the Ang II/AT1/NOX4 signaling pathway, reestablishing the cardiac insulin signaling pathway. This might optimize cardiac metabolism and improve the vasodilator function during myocardial ischemia.
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13
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Quinn DW, Pagano D, Bonser RS. Glucose and Insulin Influences on Heart and Brain in Cardiac Surgery. Semin Cardiothorac Vasc Anesth 2016; 9:173-8. [PMID: 15920645 DOI: 10.1177/108925320500900213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The elective global ischemia of on-pump coronary artery bypass surgery contributes to the incidence of postoperative mortality, complications, and use of resources. In addition to cardiopulmonary bypass and techniques for myocardial protection such as aortic cross clamp, ventricular fibrillation, and cardioplegia, the administration of systemic glucose-insulinpotassium (GIK) in the perioperative period may act as both a metabolic modulator and potential inodilator. GIK may therefore serve to protect the myocardium and promote adequate cardiac and hemodynamic performance that would improve patient recovery. Cell, tissue, and animal experiments have determined a number of mechanisms of action by which this may be achieved, with increasing focus on insulin as the key component. The original concepts centered on GIK during or after ischemia switching metabolism away from that based on nonesterified fatty acids toward a more favorable glucose-based metabolism and thus improving the efficiency of adenosine triphosphate production and glycogen preservation. Insulin's ability to reduce intracellular fatty acid metabolism may also reduce cellular membrane damage. More recently other mechanisms have also been suggested, including osmotic, oxygen free radical scavenging, and antiapoptotic and anti-inflammatory effects. However, trials that have examined the role of GIK in cardiac surgery have been small, open label, and involved a wide variety of regimens. They have demonstrated improved glycogen preservation, reduced infarct size, reduced incidences of dysrhythmias, need for inotropic agents, and low cardiac output state, and overall reduced lengths of stay. The perceived need to achieve strict blood glucose control to reduce neurologic injury and improve overall mortality have conflicted with its practical difficulties, particularly during cold cardiopulmonary bypass, and the exact role of supplemental glucose administration and resulting hyperglycemia require re-examination.
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Affiliation(s)
- David W Quinn
- Department of Cardiothoracic Surgery, Queen Elizabeth Hospital, University Hospital Birmingham NHS Trust, Edgbaston, United Kingdom
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14
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Rusai K, Herzog R, Kuster L, Kratochwill K, Aufricht C. GSK-3β inhibition protects mesothelial cells during experimental peritoneal dialysis through upregulation of the heat shock response. Cell Stress Chaperones 2013; 18:569-79. [PMID: 23494401 PMCID: PMC3745257 DOI: 10.1007/s12192-013-0410-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/29/2013] [Accepted: 01/31/2013] [Indexed: 02/04/2023] Open
Abstract
Non-physiological components of peritoneal dialysis fluids (PDF) lead to the injury of peritoneal mesothelial cells resulting in the failure of peritoneal dialysis (PD) potentially via inadequate induction of the protective heat shock response (HSR). Glycogen synthase kinase-3β (GSK-3β) is a negative regulator of cell survival partly by suppression of the HSR and is influenced by stress stimuli also present in conventional PDF. The effects of PDF on GSK-3β activation and the impact of GSK-3β inhibition with lithium (LiCl) were investigated on cell survival with special regard to HSR, in particular to heat shock transcription factor 1 (HSF-1) activation and Hsp72 production in an in vitro model of PD using MeT-5A and primary mesothelial cells. Incubation of cells with the PDF Dianeal® (glucose-based, low pH, high glucose degradation products (GDP)) and Extraneal® (icodextrin-based, low pH, low GDP) caused activation of GSK-3β compared to the other tested PDF, i.e. Balance®, Physioneal® (normal pH, glucose-based, low GDP) and Nutrineal® (moderately acidic, amino acid-based). Inhibition of GSK-3β with LiCl in Dianeal® and Extraneal®-treated cells dose-dependently decreased cell damage and death rate and was paralleled by higher HSF-1 activation and Hsp72 expression. GSK-3β is activated by low pH GDP containing PDF with and without glucose as osmotic agent, indicating that GSK-3β is involved in mesothelial cell signalling in response to experimental PD. Inhibition of GSK-3β with LiCl ameliorated cell injury and improved HSR upon PDF exposure. Thus, GSK-3β inhibitors likely have therapeutic potential as cytoprotective additive for decreasing PDF toxicity.
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Affiliation(s)
- K. Rusai
- />Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - R. Herzog
- />Zytoprotec GmbH, 1010 Vienna, Austria
| | - L. Kuster
- />Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - K. Kratochwill
- />Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- />Zytoprotec GmbH, 1010 Vienna, Austria
| | - C. Aufricht
- />Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
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15
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Demeulder B, Zarrinpashneh E, Ginion A, Viollet B, Hue L, Rider MH, Vanoverschelde JL, Beauloye C, Horman S, Bertrand L. Differential regulation of eEF2 and p70S6K by AMPKalpha2 in heart. Biochim Biophys Acta Mol Basis Dis 2013; 1832:780-90. [DOI: 10.1016/j.bbadis.2013.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 02/17/2013] [Accepted: 02/25/2013] [Indexed: 01/13/2023]
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16
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Abstract
An increasing body of clinical observations and experimental evidence suggests that cardiac dysfunction results from autonomic dysregulation of the contractile output of the heart. Excessive activation of the sympathetic nervous system and a decrease in parasympathetic tone are associated with increased mortality. Elevated levels of circulating catecholamines closely correlate with the severity and poor prognosis in heart failure. Sympathetic over-stimulation causes increased levels of catecholamines, which induce excessive aerobic metabolism leading to excessive cardiac oxygen consumption. Resulting impaired mitochondrial function causes acidosis, which results in reduction in blood flow by impairment of contractility. To the extent that the excessive aerobic metabolism resulting from adrenergic stimulation comes to a halt the energy deficit has to be compensated for by anaerobic metabolism. Glucose and glycogen become the essential nutrients. Beta-adrenergic blockade is used successfully to decrease hyperadrenergic drive. Neurohumoral antagonists block adrenergic over-stimulation but do not provide the heart with fuel for compensatory anaerobic metabolism. The endogenous hormone ouabain reduces catecholamine levels in healthy volunteers, promotes the secretion of insulin, induces release of acetylcholine from synaptosomes and potentiates the stimulation of glucose metabolism by insulin and acetylcholine. Ouabain stimulates glycogen synthesis and increases lactate utilisation by the myocardium. Decades of clinical experience with ouabain confirm the cardioprotective effects of this endogenous hormone. The so far neglected sympatholytic and vagotonic effects of ouabain on myocardial metabolism clearly make a clinical re-evaluation of this endogenous hormone necessary. Clinical studies with ouabain that correspond to current standards are warranted.
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17
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Overexpression of coupling factor 6 attenuates exercise-induced physiological cardiac hypertrophy by inhibiting PI3K/Akt signaling in mice. J Hypertens 2012; 30:778-86. [DOI: 10.1097/hjh.0b013e3283505101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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18
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Osanai T, Tanaka M, Magota K, Tomita H, Okumura K. Coupling factor 6-induced activation of ecto-F1F(o) complex induces insulin resistance, mild glucose intolerance and elevated blood pressure in mice. Diabetologia 2012; 55:520-9. [PMID: 22038518 DOI: 10.1007/s00125-011-2341-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 09/20/2011] [Indexed: 01/03/2023]
Abstract
AIMS/HYPOTHESIS Despite advances in pharmacological treatments, diabetes with hypertension continues to be a major public health problem with high morbidity and mortality rates. We recently identified a circulating peptide coupling factor 6 (CF6), which binds to the plasma membrane ATP synthase (ecto-F(1)F(o) complex), resulting in intracellular acidosis. We investigated whether overexpression of CF6 contributes to diabetes and hypertension by intracellular acidosis. METHODS Transgenic mice overexpressing CF6 (also known as ATP5J) were generated, and physiological, biochemical and molecular biology studies were performed. RESULTS CF6 overexpression elicited a sustained decrease in intracellular pH in tissues (aorta, kidney, skeletal muscle and liver, with the exception of adipose tissue) that express its receptor, the β-subunit of ecto-F(1)F(o) complex. Consistent with the receptor distribution, phospho-insulin receptor β, phosphoinositide 3-kinase activity and the phospho-Akt1:total Akt1 ratio were all decreased in the skeletal muscle and the liver in transgenic compared with wild-type mice, resulting in a decrease of plasma membrane-bound GLUT4 and an increase in hepatic glucose production. Under a high-sucrose diet, transgenic mice had insulin resistance and mild glucose intolerance; under a high-salt diet, they had elevated blood pressure with increased renal RAS-related C3 botulinum substrate 1 (RAC1)-GTP, which is an activator of mineralocorticoid receptor. CONCLUSIONS/INTERPRETATION Through its action on the β-subunit of ecto-F(1)F(o) complex, which results in intracellular acidosis, CF6 plays a crucial role in the development of insulin resistance and hypertension. This finding might advance our understanding of the mechanisms underlying diabetes and hypertension, possibly also providing a novel therapeutic target against cardiovascular disease.
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Affiliation(s)
- T Osanai
- Department of Cardiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan.
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19
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Abstract
The main role of insulin in the heart under physiological conditions is obviously the regulation of substrate utilization. Indeed, insulin promotes glucose uptake and its utilization via glycolysis. Insulin, promoting glucose as the main cardiac energy substrate, reduces myocardial O(2) consumption and increases cardiac efficiency. Moreover, insulin seems to augment cardiomyocyte contraction, while it affects favorably myocardial relaxation, increases ribosomal biogenesis and protein synthesis, stimulates vascular endothelial growth factor (VEGF) and thereby angiogenesis, suppresses apoptosis, promotes cell survival and finally ameliorates both myocardial microcirculation and coronary artery resistance, leading to increased blood perfusion of myocardium. Thus, insulin acts directly on heart muscle, and this action is mediated principally through PKB/Akt signal pathway. Under pathological conditions, such as type 2 diabetes, myocardial ischaemia, and cardiac hypertrophy, insulin signal transduction pathways and action are clearly modified. In this review we summarize the evidence that the heart is an important target of insulin action and that elimination of these actions is important in disease states.
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Affiliation(s)
- Fotios Iliadis
- Diabetes Division, 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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20
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Ginion A, Auquier J, Benton CR, Mouton C, Vanoverschelde JL, Hue L, Horman S, Beauloye C, Bertrand L. Inhibition of the mTOR/p70S6K pathway is not involved in the insulin-sensitizing effect of AMPK on cardiac glucose uptake. Am J Physiol Heart Circ Physiol 2011; 301:H469-77. [DOI: 10.1152/ajpheart.00986.2010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The AMP-activated protein kinase (AMPK) is known to increase cardiac insulin sensitivity on glucose uptake. AMPK also inhibits the mammalian target of rapamycin (mTOR)/p70 ribosomal S6 kinase (p70S6K) pathway. Once activated by insulin, mTOR/p70S6K phosphorylates insulin receptor substrate-1 (IRS-1) on serine residues, resulting in its inhibition and reduction of insulin signaling. AMPK was postulated to act on insulin by inhibiting this mTOR/p70S6K-mediated negative feedback loop. We tested this hypothesis in cardiomyocytes. The stimulation of glucose uptake by AMPK activators and insulin correlated with AMPK and protein kinase B (PKB/Akt) activation, respectively. Both treatments induced the phosphorylation of Akt substrate 160 (AS160) known to control glucose uptake. Together, insulin and AMPK activators acted synergistically to induce PKB/Akt overactivation, AS160 overphosphorylation, and glucose uptake overstimulation. This correlated with p70S6K inhibition and with a decrease in serine phosphorylation of IRS-1, indicating the inhibition of the negative feedback loop. We used the mTOR inhibitor rapamycin to confirm these results. Mimicking AMPK activators in the presence of insulin, rapamycin inhibited p70S6K and reduced IRS-1 phosphorylation on serine, resulting in the overphosphorylation of PKB/Akt and AS160. However, rapamycin did not enhance the insulin-induced stimulation of glucose uptake. In conclusion, although the insulin-sensitizing effect of AMPK on PKB/Akt is explained by the inhibition of the insulin-induced negative feedback loop, its effect on glucose uptake is independent of this mechanism. This disconnection revealed that the PKB/Akt/AS160 pathway does not seem to be the rate-limiting step in the control of glucose uptake under insulin treatment.
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Affiliation(s)
- Audrey Ginion
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Julien Auquier
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Carley R. Benton
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Céline Mouton
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Jean-Louis Vanoverschelde
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Louis Hue
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Sandrine Horman
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Christophe Beauloye
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Luc Bertrand
- Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
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Medeiros C, Frederico MJ, da Luz G, Pauli JR, Silva ASR, Pinho RA, Velloso LA, Ropelle ER, De Souza CT. Exercise training reduces insulin resistance and upregulates the mTOR/p70S6k pathway in cardiac muscle of diet-induced obesity rats. J Cell Physiol 2011; 226:666-74. [PMID: 20717955 DOI: 10.1002/jcp.22387] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Obesity and insulin resistance are rapidly expanding public health problems. These disturbances are related to many diseases, including heart pathology. Acting through the Akt/mTOR pathway, insulin has numerous and important physiological functions, such as the induction of growth and survival of many cell types and cardiac hypertrophy. However, obesity and insulin resistance can alter mTOR/p70S6k. Exercise training is known to induce this pathway, but never in the heart of diet-induced obesity subjects. To evaluate the effect of exercise training on mTOR/p70S6k in the heart of obese Wistar rats, we analyzed the effects of 12 weeks of swimming on obese rats, induced by a high-fat diet. Exercise training reduced epididymal fat, fasting serum insulin and plasma glucose disappearance. Western blot analyses showed that exercise training increased the ability of insulin to phosphorylate intracellular molecules such as Akt (2.3-fold) and Foxo1 (1.7-fold). Moreover, reduced activities and expressions of proteins, induced by the high-fat diet in rats, such as phospho-JNK (1.9-fold), NF-kB (1.6-fold) and PTP-1B (1.5-fold), were observed. Finally, exercise training increased the activities of the transduction pathways of insulin-dependent protein synthesis, as shown by increases in Raptor phosphorylation (1.7-fold), p70S6k phosphorylation (1.9-fold), and 4E-BP1 phosphorylation (1.4-fold) and a reduction in atrogin-1 expression (2.1-fold). Results demonstrate a pivotal regulatory role of exercise training on the Akt/mTOR pathway, in turn, promoting protein synthesis and antagonizing protein degradation.
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Affiliation(s)
- Cleber Medeiros
- Exercise Biochemistry and Physiology Laboratory, Postgraduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciúma, SC, Brazil
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22
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Viollet B, Horman S, Leclerc J, Lantier L, Foretz M, Billaud M, Giri S, Andreelli F. AMPK inhibition in health and disease. Crit Rev Biochem Mol Biol 2010; 45:276-95. [PMID: 20522000 DOI: 10.3109/10409238.2010.488215] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All living organisms depend on dynamic mechanisms that repeatedly reassess the status of amassed energy, in order to adapt energy supply to demand. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals managing energy balance. Control of AMPK activity involves allosteric AMP and ATP regulation, auto-inhibitory features and phosphorylation of its catalytic (alpha) and regulatory (beta and gamma) subunits. AMPK has a prominent role not only as a peripheral sensor but also in the central nervous system as a multifunctional metabolic regulator. AMPK represents an ideal second messenger for reporting cellular energy state. For this reason, activated AMPK acts as a protective response to energy stress in numerous systems. However, AMPK inhibition also actively participates in the control of whole body energy homeostasis. In this review, we discuss recent findings that support the role and function of AMPK inhibition under physiological and pathological states.
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Affiliation(s)
- Benoit Viollet
- Institut Cochin, Université Paris Descartes, CNRS UMR 8104, Paris, France.
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23
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Stuenaes JT, Bolling A, Ingvaldsen A, Rommundstad C, Sudar E, Lin FC, Lai YC, Jensen J. Beta-adrenoceptor stimulation potentiates insulin-stimulated PKB phosphorylation in rat cardiomyocytes via cAMP and PKA. Br J Pharmacol 2010; 160:116-29. [PMID: 20412069 DOI: 10.1111/j.1476-5381.2010.00677.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Genetic approaches have documented protein kinase B (PKB) as a pivotal regulator of heart function. Insulin strongly activates PKB, whereas adrenaline is not considered a major physiological regulator of PKB in heart. In skeletal muscles, however, adrenaline potentiates insulin-stimulated PKB activation without having effect in the absence of insulin. The purpose of the present study was to investigate the interaction between insulin and beta-adrenergic stimulation in regulation of PKB phosphorylation. EXPERIMENTAL APPROACH Cardiomyocytes were isolated from adult rats by collagenase, and incubated with insulin, isoprenaline, and other compounds. Protein phosphorylation was evaluated by Western blot and phospho-specific antibodies. KEY RESULTS Isoprenaline increased insulin-stimulated PKB Ser(473) and Thr(308) phosphorylation more than threefold in cardiomyocytes. Isoprenaline alone did not increase PKB phosphorylation. Isoprenaline also increased insulin-stimulated GSK-3beta Ser(9) phosphorylation approximately twofold, supporting that PKB phosphorylation increased kinase activity. Dobutamine (beta(1)-agonist) increased insulin-stimulated PKB phosphorylation as effectively as isoprenaline (more than threefold), whereas salbutamol (beta(2)-agonist) only potentiated insulin-stimulated PKB phosphorylation by approximately 80%. Dobutamine, but not salbutamol, increased phospholamban Ser(16) phosphorylation and glycogen phosphorylase activation (PKA-mediated effects). Furthermore, the cAMP analogue that activates PKA (dibutyryl-cAMP and N(6)-benzoyl-cAMP) increased insulin-stimulated PKB phosphorylation by more than threefold without effect alone. The Epac-specific activator 8-(4-chlorophenylthio)-2'-O-methyl-cAMP (007) increased insulin-stimulated PKB phosphorylation by approximately 50%. Db-cAMP and N(6)-benzoyl-cAMP, but not 007, increased phospholamban Ser(16) phosphorylation. CONCLUSIONS AND IMPLICATIONS beta-adrenoceptors are strong regulators of PKB phosphorylation via cAMP and PKA when insulin is present. We hypothesize that PKB mediates important signalling in the heart during beta-adrenergic receptors stimulation.
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Affiliation(s)
- Jorid T Stuenaes
- Department of Physiology, National Institute of Occupational Health, Oslo, Norway
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Singhal AK, Symons JD, Boudina S, Jaishy B, Shiu YT. Role of Endothelial Cells in Myocardial Ischemia-Reperfusion Injury. ACTA ACUST UNITED AC 2010; 7:1-14. [PMID: 25558187 PMCID: PMC4280830 DOI: 10.2174/1874120701007010001] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Minimizing myocardial ischemia-reperfusion injury has broad clinical implications and is a critical mediator of cardiac surgical outcomes. “Ischemic injury” results from a restriction in blood supply leading to a mismatch between oxygen supply and demand of a sufficient intensity and/or duration that leads to cell necrosis, whereas ischemia-reperfusion injury occurs when blood supply is restored after a period of ischemia and is usually associated with apoptosis (i.e. programmed cell death). Compared to vascular endothelial cells, cardiac myocytes are more sensitive to ischemic injury and have received the most attention in preventing myocardial ischemia-reperfusion injury. Many comprehensive reviews exist on various aspects of myocardial ischemia-reperfusion injury. The purpose of this review is to examine the role of vascular endothelial cells in myocardial ischemia-reperfusion injury, and to stimulate further research in this exciting and clinically relevant area. Two specific areas that are addressed include: 1) data suggesting that coronary endothelial cells are critical mediators of myocardial dysfunction after ischemia-reperfusion injury; and 2) the involvement of the mitochondrial permeability transition pore in endothelial cell death as a result of an ischemia-reperfusion insult. Elucidating the cellular signaling pathway(s) that leads to endothelial cell injury and/or death in response to ischemia-reperfusion is a key component to developing clinically applicable strategies that might minimize myocardial ischemia-reperfusion injury.
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Affiliation(s)
- Arun K Singhal
- Cardiothoracic Division, Edward J. Hines Veterans Administration Hospital, and Loyola University, Chicago, IL, USA
| | - J David Symons
- College of Health and Division of Endocrinology, Metabolism, and Diabetes, School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Sihem Boudina
- Division of Endocrinology, Metabolism and Diabetes, and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Bharat Jaishy
- Division of Endocrinology, Metabolism and Diabetes, and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Yan-Ting Shiu
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
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Sanchez Canedo C, Demeulder B, Ginion A, Bayascas JR, Balligand JL, Alessi DR, Vanoverschelde JL, Beauloye C, Hue L, Bertrand L. Activation of the cardiac mTOR/p70(S6K) pathway by leucine requires PDK1 and correlates with PRAS40 phosphorylation. Am J Physiol Endocrinol Metab 2010; 298:E761-9. [PMID: 20051528 DOI: 10.1152/ajpendo.00421.2009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Like insulin, leucine stimulates the mammalian target of rapamycin (mTOR)/p70 ribosomal S6 kinase (p70(S6K)) axis in various organs. Insulin proceeds via the canonical association of phosphatidylinositol 3-kinase (PI3K), phosphoinositide-dependent protein kinase-1 (PDK1), and protein kinase B (PKB/Akt). The signaling involved in leucine effect, although known to implicate a PI3K mechanism independent of PKB/Akt, is more poorly understood. In this study, we investigated whether PDK1 could also participate in the events leading to mTOR/p70(S6K) activation in response to leucine in the heart. In wild-type hearts, both leucine and insulin increased p70(S6K) activity whereas, in contrast to insulin, leucine was unable to activate PKB/Akt. The changes in p70(S6K) activity induced by insulin and leucine correlated with changes in phosphorylation of Thr(389), the mTOR phosphorylation site on p70(S6K), and of Ser(2448) on mTOR, both related to mTOR activity. Leucine also triggered phosphorylation of the proline-rich Akt/PKB substrate of 40 kDa (PRAS40), a new pivotal mTOR regulator. In PDK1 knockout hearts, leucine, similarly to insulin, failed to induce the phosphorylation of mTOR and p70(S6K), leading to the absence of p70(S6K) activation. The loss of leucine effect in absence of PDK1 correlated with the lack of PRAS40 phosphorylation. Moreover, the introduction in PDK1 of the L155E mutation, which is known to preserve the insulin-induced and PKB/Akt-dependent phosphorylation of mTOR/p70(S6K), suppressed all leucine effects, including phosphorylation of mTOR, PRAS40, and p70(S6K). We conclude that the leucine-induced stimulation of the cardiac PRAS40/mTOR/p70(S6K) pathway requires PDK1 in a way that differs from that of insulin.
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Lu H, Buchan RJ, Cook SA. MicroRNA-223 regulates Glut4 expression and cardiomyocyte glucose metabolism. Cardiovasc Res 2010; 86:410-20. [PMID: 20080987 DOI: 10.1093/cvr/cvq010] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
AIMS MicroRNAs (miRNAs) are important for cardiac function and tissue metabolism. The aim of the present study is to investigate the role(s) of miRNAs in the insulin-resistant heart. METHODS AND RESULTS Left ventricular biopsies were collected from patients with or without type 2 diabetes and from patients with left ventricular dysfunction. Quantitative miRNA expression analyses of 155 miRNAs revealed that miR-223 was consistently upregulated in the insulin-resistant heart. We assessed the effects of miR-223 on glucose metabolism in neonatal rat cardiomyocytes where adenoviral-mediated overexpression of miR-223 increased glucose uptake. Using in silico miRNA target prediction programs, we prioritized candidate miR-223 target genes, but observed no effect of miR-223 on myocyte enhancer factor 2c or insulin-like growth factor 1 receptor, and an unexpected miR-223-induced increase in nuclear factor IA. We next examined the effects of miR-223 on insulin signalling and glucose transport proteins. Neither phosphoinositide 3-kinase (PI3K) signalling nor AMP kinase activity was affected by miR-223 overexpression, whereas glucose transporter 4 (Glut4) protein expression was increased. miR-223 overexpression-induced Glut4 protein expression in cardiomyocytes was necessary and sufficient for increased glucose uptake as demonstrated by siRNA knockdown of Glut4. Loss-of-function studies in vivo, using a synthetic miR-223 inhibitor, confirmed the effect of miR-223 on Glut4. CONCLUSION These data demonstrate a role for miR-223 in Glut4 regulation and glucose metabolism in the heart, reveal the pleiotropic effects of miRNAs across tissues, and show that miRNAs can upregulate target genes in terminally differentiated cardiomyocytes.
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Affiliation(s)
- Han Lu
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, London W12 0NN, UK
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Huang JP, Huang SS, Deng JY, Hung LM. Impairment of insulin-stimulated Akt/GLUT4 signaling is associated with cardiac contractile dysfunction and aggravates I/R injury in STZ-diabetic rats. J Biomed Sci 2009; 16:77. [PMID: 19706162 PMCID: PMC2740847 DOI: 10.1186/1423-0127-16-77] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Accepted: 08/25/2009] [Indexed: 01/09/2023] Open
Abstract
In this study, we established systemic in-vivo evidence from molecular to organism level to explain how diabetes can aggravate myocardial ischemia-reperfusion (I/R) injury and revealed the role of insulin signaling (with specific focus on Akt/GLUT4 signaling molecules). The myocardial I/R injury was induced by the left main coronary artery occlusion for 1 hr and then 3 hr reperfusion in control, streptozotocin (STZ)-induced insulinopenic diabetes, and insulin-treated diabetic rats. The diabetic rats showed a significant decrease in heart rate, and a prolonged isovolumic relaxation (tau) which lead to decrease in cardiac output (CO) without changing total peripheral resistance (TPR). The phosphorylated Akt and glucose transporter 4 (GLUT 4) protein levels were dramatically reduced in both I/R and non-I/R diabetic rat hearts. Insulin treatment in diabetes showed improvement of contractile function as well as partially increased Akt phosphorylation and GLUT 4 protein levels. In the animals subjected to I/R, the mortality rates were 25%, 65%, and 33% in the control, diabetic, and insulin-treated diabetic group respectively. The I/R-induced arrhythmias and myocardial infarction did not differ significantly between the control and the diabetic groups. Consistent with its anti-hyperglycemic effects, insulin significantly reduced I/R-induced arrhythmias but had no effect on I/R-induced infarctions. Diabetic rat with I/R exhibited the worse hemodynamic outcome, which included systolic and diastolic dysfunctions. Insulin treatment only partially improved diastolic functions and elevated P-Akt and GLUT 4 protein levels. Our results indicate that cardiac contractile dysfunction caused by a defect in insulin-stimulated Akt/GLUT4 may be a major reason for the high mortality rate in I/R injured diabetic rats.
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Affiliation(s)
- Jiung-Pang Huang
- Department of Life Science, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China.
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Mandal A, Delamere NA, Shahidullah M. Ouabain-induced stimulation of sodium-hydrogen exchange in rat optic nerve astrocytes. Am J Physiol Cell Physiol 2008; 295:C100-10. [PMID: 18448627 DOI: 10.1152/ajpcell.90636.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Sodium-dependent transporters are inhibited indirectly by the Na-K-ATPase inhibitor ouabain. Here we report stimulation of sodium-hydrogen exchange (NHE) in ouabain-treated cells. BCECF was used to measure cytoplasmic pH in cultured rat optic nerve astrocytes. Ammonium chloride was applied to acid load the cells. On removal of ammonium chloride, cytoplasmic pH fell abruptly, then gradually recovered toward baseline. Ouabain (1 microM) did not change cell sodium content, but the rate of pH recovery increased by 68%. Ouabain speeded pH recovery both in the presence and absence of bicarbonate. In bicarbonate-free medium, dimethylamiloride, an NHE inhibitor, eliminated the effect of 1 microM ouabain on pH recovery. Western blot analysis showed an NHE1 immunoreactive band but not NHE2, NHE3, or NHE4. Immunoprecipitation studies showed phosphorylation of NHE1 in cells treated with 1 microM ouabain. Ouabain evoked an increase of cAMP, and the effect of 1 microM ouabain on pH recovery was abolished by H-89, a protein kinase A inhibitor. 8-Bromoadenosine-cAMP increased the pH recovery rate, and this recovery was not further increased by ouabain. Although 1 microM ouabain did not alter cytoplasmic calcium concentration, it stimulated calcium entry after store depletion, a response abolished by 2-APB. Ouabain-induced stimulation of pH recovery was suppressed by inhibitors of capacitative calcium entry, SKF-96365, and 2-APB, as well as the cytoplasmic calcium chelator BAPTA. The cAMP increase in ouabain-treated cells was abolished by BAPTA and 2-APB. Taken together, the results are consistent with increased capacitative calcium entry and subsequent cAMP-PKA-dependent stimulation of NHE1 in ouabain-treated cells.
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Affiliation(s)
- Amritlal Mandal
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA
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Ségalen C, Longnus SL, Baetz D, Counillon L, Van Obberghen E. 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside reduces glucose uptake via the inhibition of Na+/H+ exchanger 1 in isolated rat ventricular cardiomyocytes. Endocrinology 2008; 149:1490-8. [PMID: 18187546 DOI: 10.1210/en.2007-1326] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
AMP-activated protein kinase (AMPK) is an energy-sensing enzyme that is activated by an increased AMP/ATP ratio. AMPK is now well recognized to induce glucose uptake in skeletal muscle and heart. 5-Aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) is phosphorylated to form the AMP analog ZMP, which activates AMPK. Its effects on glucose transport appear to be tissue specific. The purpose of our study was to examine the effect of AICAR on insulin-induced glucose uptake in adult rat ventricular cardiomyocytes. We studied isolated adult rat ventricular cardiomyocytes treated or not with the AMPK activators AICAR and metformin and, subsequently, with insulin or not. Insulin action was investigated by determining deoxyglucose uptake, insulin receptor substrate-1- or -2-associated phosphatidylinositol 3-kinase activity and protein kinase B (PKB) cascade using antibodies to PKB, glycogen synthase kinase-3, and Akt substrate of 160 kDa. Intracellular pH was evaluated using the fluorescent pH-sensitive dye 2',7'-bis (2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) and Na(+)/H(+) exchanger 1 (NHE1) activity was assessed using the NH(4)(+) prepulse method. Our key findings are as follows. AICAR and metformin enhance insulin signaling downstream of PKB. Metformin potentiates insulin-induced glucose uptake, but surprisingly, AICAR inhibits both basal and insulin-induced glucose uptake. Moreover, we found that AICAR decreases intracellular pH, via inhibition of NHE1. In conclusion, AMPK potentiates insulin signaling downstream of PKB in isolated cardiac myocytes, consistent with findings in the heart in vivo. Furthermore, AICAR inhibits basal and insulin-induced glucose uptake in isolated cardiac myocytes via the inhibition of NHE1 and the subsequent reduction of intracellular pH. Importantly, AICAR exerts these effects in a manner independent of AMPK activation.
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Affiliation(s)
- Coralie Ségalen
- Faculté de Medecine, Institut National de la Santé et de la Recherche Médicale Unité 907, Avenue de Valombrose, Nice, France
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Barillas R, Friehs I, Cao-Danh H, Martinez JF, del Nido PJ. Inhibition of glycogen synthase kinase-3beta improves tolerance to ischemia in hypertrophied hearts. Ann Thorac Surg 2007; 84:126-33. [PMID: 17588398 PMCID: PMC3444259 DOI: 10.1016/j.athoracsur.2007.02.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 02/04/2007] [Accepted: 02/06/2007] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hypertrophied myocardium is more susceptible to ischemia/reperfusion injury, in part owing to impaired insulin-mediated glucose uptake. Glycogen synthase kinase-3beta (GSK-3beta) is a key regulatory enzyme in glucose metabolism that, when activated, phosphorylates/inactivates target enzymes of the insulin signaling pathway. Glycogen synthase kinase-3beta is regulated upstream by Akt-1. We sought to determine whether GSK-3beta is activated in ischemic hypertrophied myocardium owing to impaired Akt-1 function, and whether inhibition with lithium (Li) or indirubin-3'-monoxime,5-iodo- (IMI), a specific inhibitor, improves post-ischemic myocardial recovery by improving glucose metabolism. METHODS Pressure-overload hypertrophy was achieved by aortic banding in neonatal rabbits. At 6 weeks, isolated hypertrophied hearts underwent 30 minutes of normothermic ischemia and reperfusion with or without a GSK-3beta inhibitor (0.1 mM Li; 1 microM IMI) as cardioplegic additives. Cardiac function was measured before and after ischemia. Expression, activity of Akt-1 and GSK-3beta, and lactate were determined at end-ischemia. RESULTS Contractile function after ischemia was better preserved in hypertrophied hearts treated with GSK-3beta inhibitors. Activity of Akt-1 was significantly impaired in hypertrophied myocardium at end-ischemia. Glycogen synthase kinase-3beta enzymatic activity at end-ischemia was increased in hypertrophied hearts and was blocked by Li or IMI concomitant with significantly increased lactate production, indicating increased glycolysis. CONCLUSIONS Regulatory inhibition of GSK-3beta by Akt-1 in hypertrophied hearts is impaired, leading to activation during ischemia. Inhibition of GSK-3beta by Li or IMI improves tolerance to ischemia/reperfusion injury in hypertrophied myocardium. The likely protective mechanism is an increase in insulin-mediated glucose uptake, resulting in greater substrate availability for glycolysis during ischemia and early reperfusion.
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Affiliation(s)
- Rodrigo Barillas
- Department of Cardiac Surgery, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA
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Bertrand L, Ginion A, Beauloye C, Hebert AD, Guigas B, Hue L, Vanoverschelde JL. AMPK activation restores the stimulation of glucose uptake in an in vitro model of insulin-resistant cardiomyocytes via the activation of protein kinase B. Am J Physiol Heart Circ Physiol 2006; 291:H239-50. [PMID: 16489105 DOI: 10.1152/ajpheart.01269.2005] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diabetic hearts are known to be more susceptible to ischemic disease. Biguanides, like metformin, are known antidiabetic drugs that lower blood glucose concentrations by decreasing hepatic glucose production and increasing glucose disposal in muscle. Part of these metabolic effects is thought to be mediated by the activation of AMP-activated protein kinase (AMPK). In this work, we studied the relationship between AMPK activation and glucose uptake stimulation by biguanides and oligomycin, another AMPK activator, in both insulin-sensitive and insulin-resistant cardiomyocytes. In insulin-sensitive cardiomyocytes, insulin, biguanides and oligomycin were able to stimulate glucose uptake with the same efficiency. Stimulation of glucose uptake by insulin or biguanides was correlated to protein kinase B (PKB) or AMPK activation, respectively, and were additive. In insulin-resistant cardiomyocytes, where insulin stimulation of glucose uptake was greatly reduced, biguanides or oligomycin, in the absence of insulin, induced a higher stimulation of glucose uptake than that obtained in insulin-sensitive cells. This stimulation was correlated with the activation of both AMPK and PKB and was sensitive to the phosphatidylinositol-3-kinase/PKB pathway inhibitors. Finally, an adenoviral-mediated expression of a constitutively active form of AMPK increased both PKB phosphorylation and glucose uptake in insulin-resistant cardiomyocytes. We concluded that AMPK activators, like biguanides and oligomycin, are able to restore glucose uptake stimulation, in the absence of insulin, in insulin-resistant cardiomyocytes via the additive activation of AMPK and PKB. Our results suggest that AMPK activation could restore normal glucose metabolism in diabetic hearts and could be a potential therapeutic approach to treat insulin resistance.
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Affiliation(s)
- Luc Bertrand
- Division of Cardiology, School of Medicine, Université Catholique de Louvain, Brussels, Belgium.
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Abstract
AMP-activated protein kinase (AMPK) has emerged as a key regulator of energy metabolism in the heart. The high energy demands of the heart are primarily met by the metabolism of both fatty acids and glucose, both processes being regulated by AMPK. During myocardial ischaemia a rapid activation of AMPK occurs, resulting in an activation of both glucose uptake and glycolysis, as well as an increase in fatty acid oxidation. This activation of AMPK has the potential to increase energy production and to inhibit apoptosis, thereby protecting the heart during the ischaemic stress. However, at clinically relevant high levels of fatty acids, ischaemic-induced activation of AMPK also stimulates fatty acid oxidation during and following ischaemia. This can contribute to ischaemic injury secondary to an inhibition of glucose oxidation, which results in a decrease in cardiac efficiency. In a number of other non-cardiac tissues, AMPK has been shown to have pro-apoptotic effects. As a result, the question of whether AMPK activation benefits or harms the ischaemic heart remains controversial. The role of AMPK in cardiac hypertrophy is also controversial. Activation of AMPK inhibits protein synthesis, and may be an adaptive response to pathological cardiac hypertrophy. However, none of mouse models of AMPK deficiency (excluding those that may involve the gamma2 subunit mutations) demonstrate increased cardiac mass, suggesting that AMPK is not essential for restriction of cardiac growth. In addition to the potential effects of AMPK on myofibrillar hypertrophy associated with pressure overload, there is also controversy with respect to the cardiac hypertrophy associated with the gamma2 subunit mutations. In the cardiac hypertrophy associated with glycogen overload, both activating and inactivating mutations of AMPK in mice are associated with a marked cardiac hypertrophy. This review will address the issue of whether AMPK activation acts as an enemy or ally to the ischaemic and hypertrophied heart. Resolving this issue has important implications as to whether therapeutic approaches to protect the ischaemic heart should be developed which either activate or inhibit AMPK.
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Affiliation(s)
- Jason R B Dyck
- Cardiovascular Research Group, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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Quinn DW, Pagano D, Bonser RS, Rooney SJ, Graham TR, Wilson IC, Keogh BE, Townend JN, Lewis ME, Nightingale P. Improved myocardial protection during coronary artery surgery with glucose-insulin-potassium: A randomized controlled trial. J Thorac Cardiovasc Surg 2006; 131:34-42. [PMID: 16399292 DOI: 10.1016/j.jtcvs.2005.05.057] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 05/11/2005] [Accepted: 05/26/2005] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We sought to assess the role of glucose-insulin-potassium in providing myocardial protection in nondiabetic patients undergoing coronary artery surgery with cardiopulmonary bypass. METHODS A prospective, randomized, double-blind, placebo-controlled trial was conducted at a single-center university hospital performing adult cardiac surgery. Two hundred eighty nondiabetic adult patients undergoing first-time elective or urgent isolated multivessel coronary artery bypass grafting were prospectively randomized to receive glucose-insulin-potassium infusion or placebo (dextrose 5%) before, during, and for 6 hours after surgical intervention. Anesthetic, cardiopulmonary bypass, myocardial protection, and surgical techniques were standardized. The primary end point was postreperfusion cardiac index. Secondary end points were systemic vascular resistance index, the incidence of low cardiac output episodes, inotrope and vasoconstrictor use, and biochemical-electrocardiographic evidence of myocardial injury. The incidence of dysrhythmias and infections requiring treatment was recorded prospectively. RESULTS The glucose-insulin-potassium group experienced higher cardiac indices (P < .001) throughout infusion and reduced vascular resistance (P < .001). The incidence of low cardiac output episodes was 15.9% (22/138) in the glucose-insulin-potassium group and 27.5% (39/142) in the placebo group (P = .021). Inotropes were required in 18.8% (26/138) of the glucose-insulin-potassium group and 40.8% (58/142) of the placebo group (P < .001). Fewer patients in the glucose-insulin-potassium group (12.3% [16/133]) versus those in the placebo group (23.4% [32/137]) had significant myocardial injury (P = .017). Noncardiac morbidity was not different. CONCLUSION Glucose-insulin-potassium therapy improves early postoperative cardiovascular performance, reduces inotrope requirement, and might reduce myocardial injury. These potential benefits are not at the expense of increased noncardiac morbidity.
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Affiliation(s)
- David W Quinn
- Department of Cardiothoracic Surgery, Queen Elizabeth Hospital, University Hospital Birmingham NHS Trust, Edgbaston, Birmingham, United Kingdom
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Horman S, Vertommen D, Heath R, Neumann D, Mouton V, Woods A, Schlattner U, Wallimann T, Carling D, Hue L, Rider MH. Insulin antagonizes ischemia-induced Thr172 phosphorylation of AMP-activated protein kinase alpha-subunits in heart via hierarchical phosphorylation of Ser485/491. J Biol Chem 2005; 281:5335-40. [PMID: 16340011 DOI: 10.1074/jbc.m506850200] [Citation(s) in RCA: 276] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies showed that insulin antagonizes AMP-activated protein kinase activation by ischemia and that protein kinase B might be implicated. Here we investigated whether the direct phosphorylation of AMP-activated protein kinase by protein kinase B might participate in this effect. Protein kinase B phosphorylated recombinant bacterially expressed AMP-activated protein kinase heterotrimers at Ser(485) of the alpha1-subunits. In perfused rat hearts, phosphorylation of the alpha1/alpha2 AMP-activated protein kinase subunits on Ser(485)/Ser(491) was increased by insulin and insulin pretreatment decreased the phosphorylation of the alpha-subunits at Thr(172) in a subsequent ischemic episode. It is proposed that the effect of insulin to antagonize AMP-activated protein kinase activation involves a hierarchical mechanism whereby Ser(485)/Ser(491) phosphorylation by protein kinase B reduces subsequent phosphorylation of Thr(172) by LKB1 and the resulting activation of AMP-activated protein kinase.
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Affiliation(s)
- Sandrine Horman
- Hormone and Metabolic Research Unit, Christian de Duve Institute of Cellular Pathology and Université catholique de Louvain, Avenue Hippocrate 75, B-1200 Brussels, Belgium.
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Paxton R, Ye L. Regulation of heart insulin receptor tyrosine kinase activity by magnesium and spermine. Mol Cell Biochem 2005; 277:7-17. [PMID: 16132709 DOI: 10.1007/s11010-005-5755-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 11/02/2004] [Indexed: 11/26/2022]
Abstract
Insulin action and aspects of the insulin-signaling pathway have been studied in the heart although the direct regulation of the heart's insulin receptor has not been explored. This study describes the first purification and characterization of the mammalian (rabbit, rat and bovine) heart insulin receptor. The rabbit heart IR showed maximum insulin binding of 18 microg/mg (approximately 1 mole insulin/mole (alpha2beta2) receptor) and a curvilinear Scatchard plot with a high affinity KD for insulin binding of approximately 4 nM at optimal pH (7.8) and NaCl concentration (150 mM). The insulin receptor tyrosine kinase activity was stimulated by insulin, Mg2+ (half-maximum response at approximately 5.6-10.6 nM and approximately 8.5 mM, respectively) and by the physiological polyamines, spermine and spermidine. The stimulation by Mg2+ and the polyamines occurred with and without insulin. These characteristics of the heart insulin receptor provide a mechanism for regulating the activity of the receptor's tyrosine kinase activity by the intracellular free Mg2+ concentration and the polyamines in the absence and presence of insulin.
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Affiliation(s)
- Ralph Paxton
- Laboratory of Metabolic Disorders, Auburn University, Auburn, AL 36849, USA.
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Friehs I, Cao-Danh H, Nathan M, McGowan FX, del Nido PJ. Impaired insulin-signaling in hypertrophied hearts contributes to ischemic injury. Biochem Biophys Res Commun 2005; 331:15-22. [PMID: 15845351 PMCID: PMC3444251 DOI: 10.1016/j.bbrc.2005.03.120] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Indexed: 11/22/2022]
Abstract
Despite increased glucose utilization by hypertrophied myocardium, these hearts exhibit a slower rate of glucose uptake (GU). We hypothesized that, in hypertrophied myocardium, a defect of the insulin-responsive glucose transporter is responsible for impaired GU and metabolism during ischemia, contributing to post-ischemic myocardial dysfunction. In a rabbit model of pressure-overload hypertrophy, GU ((31)P NMR spectroscopy) and total/phosphorylated insulin-signaling intermediates were assayed: insulin-receptor, insulin-receptor-substrate-1 (IRS-1), phosphatidylinositol-3-kinase (PI3-k), GLUT-4 translocation and contractile function in an isolated heart ischemia/reperfusion model. Total protein was not different between hypertrophied and control hearts. Phosphorylation of IRS-1 and PI3-k activity was significantly lower in hypertrophy during ischemia. GU was impaired pre-ischemia in hypertrophy, remained lower during early reperfusion, and was associated with impaired recovery of contractile function. In conclusion, a defect in IRS-1 phosphorylation and PI3-k activation in hypertrophied hearts restricts insulin-mediated GLUT-4 translocation and ischemia, a known stimulus of GLUT-4 translocation, does not compensate for this defect.
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Affiliation(s)
- Ingeborg Friehs
- Department of Cardiac Surgery, Children’s Hospital Boston and Harvard Medical School, Boston, USA
| | - Hung Cao-Danh
- Department of Cardiac Surgery, Children’s Hospital Boston and Harvard Medical School, Boston, USA
| | - Meena Nathan
- Department of Cardiac Surgery, Children’s Hospital Boston and Harvard Medical School, Boston, USA
| | - Francis X. McGowan
- Department of Anesthesiology/Perioperative and Pain Medicine, Children’s Hospital Boston and Harvard Medical School, Boston, USA
| | - Pedro J. del Nido
- Department of Cardiac Surgery, Children’s Hospital Boston and Harvard Medical School, Boston, USA
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Zhang Y, Oliver JR, Horowitz JD. The Role of Endothelin in Mediating Ischemia/Hypoxia-Induced Atrial Natriuretic Peptide Release. J Cardiovasc Pharmacol 2004; 43:227-33. [PMID: 14716210 DOI: 10.1097/00005344-200402000-00010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The aim of the present study was to investigate the putative role of endothelin (ET) in mediating ischemia/hypoxia-induced ANP release utilizing exogenous ET-1 or ET receptor antagonists (BQ-123 or Bosentan). Isolated rat hearts with non-distended atria were perfused using a Langendorff apparatus and heart rate maintained constant via atrial pacing. Global ischemia was induced either by direct reduction in perfusion or by infusion of exogenous ET-1 (5 x 10(-10) M) for 30 minutes. Perfusion with the ET receptor antagonists, BQ-123 (10(-6) M) or Bosentan (10(-5) M) was initiated 10 minutes before onset of ischemia. Moderate or severe ischemia was induced by reduction (52-61% and 70-82%, respectively) in perfusate flow. Thirty minutes of ischemia/hypoxia (5% O2) was followed by 30 minutes of reperfusion/re-oxygenation. Both moderate and severe ischemia increased ANP release. BQ-123 and Bosentan did not affect basal or ischemia-induced ANP release. Exogenous ET-1 perfusion induced a late increase in ANP release (P < 0.01) that did not exceed the increase in ANP release associated with equivalent direct flow reduction. Hypoxia induced an 8-fold increase in ANP release rate. The ANP release rate returned toward basal levels after re-oxygenation. Bosentan, but not BQ-123, significantly attenuated (P < 0.01) hypoxia-induced ANP release. In conclusion, in this system, ANP release is stimulated by moderate (or severe) ischemia and severe hypoxia independent of change in atrial distension; endogenous ET does not mediate basal and ischemia-induced ANP release; and hypoxia-induced ANP release is partially modulated via interaction with endogenous ET.
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Affiliation(s)
- Yi Zhang
- High Blood Pressure Research Unit, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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39
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Horman S, Beauloye C, Vertommen D, Vanoverschelde JL, Hue L, Rider MH. Myocardial ischemia and increased heart work modulate the phosphorylation state of eukaryotic elongation factor-2. J Biol Chem 2003; 278:41970-6. [PMID: 12920134 DOI: 10.1074/jbc.m302403200] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein synthesis, in particular peptide chain elongation, is an energy-consuming biosynthetic process. AMP-activated protein kinase (AMPK) is a key regulatory enzyme involved in cellular energy homeostasis. Therefore, we tested the hypothesis that, as in liver, it could mediate the inhibition of protein synthesis by oxygen deprivation in heart by modulating the phosphorylation of eukaryotic elongation factor-2 (eEF2), which becomes inactive in its phosphorylated form. In anoxic cardiomyocytes, AMPK activation was associated with an inhibition of protein synthesis and an increase in phosphorylation of eEF2. Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), did not mimic the effect of oxygen deprivation to inhibit protein synthesis in cardiomyocytes or lead to eEF2 phosphorylation in perfused hearts, suggesting that AMPK activation did not inhibit mTOR/p70 ribosomal protein S6 kinase (p70S6K) signaling. Human recombinant eEF2 kinase (eEF2K) was phosphorylated by AMPK in a time- and AMP-dependent fashion, and phosphorylation led to eEF2K activation, similar to that observed in extracts from ischemic hearts. In contrast, increasing the workload resulted in a dephosphorylation of eEF2, which was rapamycin-insensitive, thus excluding a role for mTOR in this effect. eEF2K activity was unchanged by increasing the workload, suggesting that the decrease in eEF2 phosphorylation could result from the activation of an eEF2 phosphatase.
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Affiliation(s)
- Sandrine Horman
- Hormone and Metabolic Research Unit, Christian de Duve Institute of Cellular Pathology, University of Louvain Medical School, Avenue Hippocrate 75, ICP-UCL 7529, B-1200 Brussels, Belgium
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40
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Kovacic S, Soltys CLM, Barr AJ, Shiojima I, Walsh K, Dyck JRB. Akt activity negatively regulates phosphorylation of AMP-activated protein kinase in the heart. J Biol Chem 2003; 278:39422-7. [PMID: 12890675 DOI: 10.1074/jbc.m305371200] [Citation(s) in RCA: 300] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the heart, insulin stimulates a variety of kinase cascades and controls glucose utilization. Because insulin is able to activate Akt and inactivate AMP-activated protein kinase (AMPK) in the heart, we hypothesized that Akt can regulate the activity of AMPK. To address the potential existence of this novel signaling pathway, we used a number of experimental protocols to activate Akt in cardiac myocytes and monitored the activation status of AMPK. Mouse hearts perfused in the presence of insulin demonstrated accelerated glycolysis and glucose oxidation rates as compared with non-insulin-perfused hearts. In addition, insulin caused an increase in Akt phosphorylation and a decrease in AMPK phosphorylation at its major regulatory site (threonine 172 of the alpha catalytic subunit). Transgenic mice overexpressing a constitutively active mutant form of Akt1 displayed decreased phosphorylation of cardiac alpha-AMPK. Isolated neonatal cardiac myocytes infected with an adenovirus expressing constitutively active mutant forms of either Akt1 or Akt2 also suppressed AMPK phosphorylation. However, Akt-dependent depression of alpha-AMPK phosphorylation could be overcome in the presence of the AMPK activator, metformin, suggesting that an override mechanism exists that can restore AMPK activity. Taken together, this study suggests that there is cross-talk between the AMPK and Akt pathways and that Akt activation can lead to decreased AMPK activity. In addition, our data suggest that the ability of insulin to inhibit AMPK may be controlled via an Akt-mediated mechanism.
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Affiliation(s)
- Suzanne Kovacic
- Molecular Cardiology, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118-2256, USA
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41
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Mora A, Davies AM, Bertrand L, Sharif I, Budas GR, Jovanović S, Mouton V, Kahn CR, Lucocq JM, Gray GA, Jovanović A, Alessi DR. Deficiency of PDK1 in cardiac muscle results in heart failure and increased sensitivity to hypoxia. EMBO J 2003; 22:4666-76. [PMID: 12970179 PMCID: PMC212735 DOI: 10.1093/emboj/cdg469] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We employed Cre/loxP technology to generate mPDK1(-/-) mice, which lack PDK1 in cardiac muscle. Insulin did not activate PKB and S6K, nor did it stimulate 6-phosphofructo-2-kinase and production of fructose 2,6-bisphosphate, in the hearts of mPDK1(-/-) mice, consistent with PDK1 mediating these processes. All mPDK1(-/-) mice died suddenly between 5 and 11 weeks of age. The mPDK1(-/-) animals had thinner ventricular walls, enlarged atria and right ventricles. Moreover, mPDK1(-/-) muscle mass was markedly reduced due to a reduction in cardiomyocyte volume rather than cardiomyocyte cell number, and markers of heart failure were elevated. These results suggested mPDK1(-/-) mice died of heart failure, a conclusion supported by echocardiographic analysis. By employing a single-cell assay we found that cardiomyocytes from mPDK1(-/-) mice are markedly more sensitive to hypoxia. These results establish that the PDK1 signalling network plays an important role in regulating cardiac viability and preventing heart failure. They also suggest that a deficiency of the PDK1 pathway might contribute to development of cardiac disease in humans.
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Affiliation(s)
- Alfonso Mora
- MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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Yang J, Gillingham AK, Hodel A, Koumanov F, Woodward B, Holman GD. Insulin-stimulated cytosol alkalinization facilitates optimal activation of glucose transport in cardiomyocytes. Am J Physiol Endocrinol Metab 2002; 283:E1299-307. [PMID: 12388133 DOI: 10.1152/ajpendo.00341.2002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abnormalities in intracellular pH regulation have been proposed to be important in type 2 diabetes and the associated cardiomyopathy and hypertension. We have therefore investigated the dependence of insulin-stimulated glucose transport on cytosolic pH in cardiomyocytes. Insulin treatment of cardiomyocytes resulted in a marked alkalinization of the cytoplasm as measured using carboxy-semi-napthorhodofluor-1. The alkalinizing effect of insulin was blocked by treatment with either cariporide (which inhibits the Na+/H+ exchanger) or by bafilomycin A1 (which inhibits H+-ATPase activity). After treatments with cariporide or bafilomycin A1, insulin stimulation of insulin receptor and insulin receptor substrate-1 phosphorylation and Akt activity were normal. In contrast, glucose transport activity and the levels of functional GLUT4 at the plasma membrane (detected using an exofacial photolabel) were reduced by approximately 50%. Immunocytochemical analysis revealed that insulin treatment caused a translocation of the GLUT4 from perinuclear structures and increased its co-localization with cell surface syntaxin 4. However, neither cariporide nor bafilomycin A1 treatment reduced the translocation of immunodetectable GLUT4 to the sarcolemma region of the cell. It is therefore hypothesized that insulin-stimulated cytosol alkalinization facilitates the final stages of translocation and incorporation of fully functional GLUT4 at the surface-limiting membrane.
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Affiliation(s)
- Jing Yang
- Departments of Biology and Biochemistry and Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, United Kingdom
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43
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Beauloye C, Marsin AS, Bertrand L, Vanoverschelde JL, Rider MH, Hue L. The stimulation of heart glycolysis by increased workload does not require AMP-activated protein kinase but a wortmannin-sensitive mechanism. FEBS Lett 2002; 531:324-8. [PMID: 12417335 DOI: 10.1016/s0014-5793(02)03552-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Increasing heart workload stimulates glycolysis by enhancing glucose transport and fructose-2,6-bisphosphate (Fru-2,6-P(2)), the latter resulting from 6-phosphofructo-2-kinase (PFK-2) activation. Here, we investigated whether adenosine monophosphate (AMP)-activated protein kinase (AMPK) mediates PFK-2 activation in hearts submitted to increased workload. When heart work was increased, PFK-2 activity, Fru-2,6-P(2) content and glycolysis increased, whereas the AMP:adenosine triphosphate (ATP) and phosphocreatine/creatine (PCr:Cr) ratios, and AMPK activity remained unchanged. Wortmannin, the well-known phosphatidylinositol-3-kinase inhibitor, blocked the activation of protein kinase B and the increase in glycolysis and Fru-2,6-P(2) content induced by increased work. Therefore, the control of heart glycolysis by contraction differs from that in skeletal muscle where AMPK is involved.
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Affiliation(s)
- Christophe Beauloye
- Hormone and Metabolic Research Unit, Christian de Duve Institute of Cellular Pathology, ICP-UCL 7529, 75, avenue Hippocrate, Brussels, Belgium
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Opie LH, Sack MN. Metabolic plasticity and the promotion of cardiac protection in ischemia and ischemic preconditioning. J Mol Cell Cardiol 2002; 34:1077-89. [PMID: 12392880 DOI: 10.1006/jmcc.2002.2066] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The concept of metabolic protection of the ischemic myocardium is in constant evolution and has recently been supported by clinical studies. Historically, enhanced glucose metabolism and glycolysis were proposed as anti-ischemic cardioprotection. This hypothesis is supported by the sub-cellular linkage between key glycolytic enzymes and the activity of two survival-promoting membrane-bound pumps, namely the sodium-potassium ATPase, and the calcium uptake pump of the sarcoplasmic reticulum. Moreover, improved resistance against ischemia follows the administration of glucose-insulin-potassium in a variety of animal models and in patients following acute myocardial infarction. The metabolic plasticity paradigm has now been expanded to include (1) the benefit of improved coupling of glycolysis to glucose oxidation, which explains the action of anti-ischemic fatty acid inhibitors such as trimetazidine and ranolazine; (2) the role of malonyl CoA in the glucose-fatty acid interaction; and (3) the anti-apoptotic role of insulin. Furthermore, we argue for a protective role of increased glucose uptake in the preconditioning paradigm. Additionally, we postulate an adaptive role of mitochondrial respiration in the promotion of cardioprotection in the context of ischemic preconditioning. The mechanisms driving these mitochondrial perturbations are still unknown, but are hypothesized to involve an initial modest uncoupling of respiration from the production of mitochondrial ATP. These perturbations are in turn thought to prime the mitochondria to augment mitochondrial respiration during a subsequent ischemic insult to the heart. In this review we discuss studies that demonstrate how metabolic plasticity can promote cardioprotection against ischemia and reperfusion injury and highlight areas that require further characterization.
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Affiliation(s)
- Lionel H Opie
- Hatter Institute for Cardiology Research and Medical Research Council Inter-University Cape Heart Group, Cape Heart Centre, University of Cape Town Medical School, South Africa.
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Hue L, Beauloye C, Marsin AS, Bertrand L, Horman S, Rider MH. Insulin and ischemia stimulate glycolysis by acting on the same targets through different and opposing signaling pathways. J Mol Cell Cardiol 2002; 34:1091-7. [PMID: 12392881 DOI: 10.1006/jmcc.2002.2063] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The stimulation of heart glycolysis by insulin and ischemia involves the recruitment of the glucose transporter GLUT4 to the plasma membrane and the activation of 6-phosphofructo-2-kinase (PFK-2), which in turn increases the concentration of fructose 2,6-bisphosphate, a well-known stimulator of glycolysis. This review focuses on the mechanisms responsible for PFK-2 activation by insulin and ischemia in heart. Heart PFK-2 is phosphorylated by various protein kinases, including protein kinase B (PKB), thought to mediate most, if not all, short-term effects of insulin, and the AMP-activated protein kinase (AMPK), known to be activated under anaerobic conditions. We found that PKB is not required for PFK-2 activation by insulin and we partially purified an insulin-sensitive PFK-2 kinase, that differs from PKB and from other insulin-stimulated protein kinases. We also demonstrated that AMPK mediates PFK-2 activation by ischemia. Finally, our study of the interaction between the signaling pathways of insulin and ischemia revealed opposite effects on signaling. Intracellular acidosis induced by ischemia inhibited insulin signaling, whereas insulin pretreatment antagonized AMPK activation by ischemia.
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Affiliation(s)
- Louis Hue
- Hormone and Metabolic Research Unit, Christian de Duve International Institute of Cellular and Molecular Pathology, and University of Louvain Medical School, Avenue Hippocrate, 75, B-1200, Brussels, Belgium.
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Massion PB, Moniotte S, Balligand JL. Nitric oxide: does it play a role in the heart of the critically ill? Curr Opin Crit Care 2001; 7:323-36. [PMID: 11805529 DOI: 10.1097/00075198-200110000-00003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nitric oxide regulates many aspects of myocardial function, not only in the normal heart but also in ischemic and nonischemic heart failure, septic cardiomyopathy, cardiac allograft rejection, and myocarditis. Accumulating evidence implicates the endogenous production of nitric oxide in the regulation of myocardial contractility, distensibility, heart rate, coronary vasodilation, myocardial oxygen consumption, mitochondrial respiration, and apoptosis. The effects of nitric oxide promote left ventricular mechanical efficiency, ie, appropriate matching between cardiac work and myocardial oxygen consumption. Most of these beneficial effects are attributed to the low physiologic concentrations generated by the constitutive endothelial or neuronal nitric oxide synthase. By contrast, inducible nitric oxide synthase generates larger concentrations of nitric oxide over longer periods of time, leading to mostly detrimental effects. In addition, the recently identified beta3-adrenoceptor mediates a negative inotropic effect through coupling to endothelial nitric oxide synthase and is overexpressed in heart failure. An imbalance between beta 1 and beta2-adrenoceptor and beta3-adrenoceptor, with a prevailing influence of beta3-adrenoceptor, may play a causal role in the pathogenesis of cardiac diseases such as terminal heart failure. Likewise, changes in the expression of endothelial nitric oxide synthase or inducible nitric oxide synthase within the myocardium may alter the delicate balance between the effects of nitric oxide produced by either of these isoforms. New treatments such as selective inducible nitric oxide synthase blockade, endothelial nitric oxide synthase promoting therapies, and selective beta3-adrenoceptor modulators may offer promising new therapeutic approaches to optimize the care of critically ill patients according to their stage and specific underlying disease process.
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Affiliation(s)
- P B Massion
- Department of Internal Medicine, Unit of Pharmacology and Therapeutics, Université catholique de Louvain, Brussels, Belgium
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47
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Stavrou BM, Beck C, Flores NA. Changes in extracellular pH and myocardial ischaemia alter the cardiac effects of diadenosine tetraphosphate and pentaphosphate. Br J Pharmacol 2001; 134:639-47. [PMID: 11588119 PMCID: PMC1572982 DOI: 10.1038/sj.bjp.0704288] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The structural conformation of diadenosine tetraphosphate (Ap(4)A) and pentaphosphate (Ap(5)A) has been reported to alter as pH is reduced. As such, it is possible that the cardiac effects of Ap(4)A and Ap(5)A vary during acidosis and myocardial ischaemia due to changes in ligand structure, receptor proteins or intracellular signalling. 2. We investigated whether the cardiac electrophysiological and coronary vasomotor effects of Ap(4)A and Ap(5)A are preserved under conditions of extracellular acidosis (pH 6.5) and alkalosis (pH 8.5) and whether Ap(4)A has any electrophysiological or antiarrhythmic effects during ischaemia. 3. Transmembrane right ventricular action potentials, refractory periods and coronary perfusion pressure were recorded from isolated, Langendorff-perfused guinea-pig hearts under constant flow conditions. The effects of 1 nM and 1 microM Ap(4)A and Ap(5)A were studied at pH 7.4, 6.5 and 8.5. The effects of 1 microM Ap(4)A were studied during global low-flow ischaemia and reperfusion. 4. At pH 7.4, Ap(4)A and Ap(5)A increased action potential duration (APD(95)) and refractory period (RP) and reduced coronary perfusion pressure. The electrophysiological effects were absent at pH 6.5 while the reductions in perfusion pressure were attenuated. At pH 8.5, Ap(4)A increased RP but the effects of Ap(4)A and Ap(5)A on perfusion pressure were attenuated. During ischaemia, Ap(4)A had no antiarrhythmic or electrophysiological effects. 5. These data demonstrate the importance of extracellular pH in influencing the effects of Ap(4)A and Ap(5)A on the heart and indicate that any potentially cardioprotective effects of these compounds during normal perfusion at physiological pH are absent during ischaemia.
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Affiliation(s)
- Brigitte M Stavrou
- Academic Cardiology Unit, National Heart and Lung Institute, Imperial College School of Medicine, London
| | - Caroline Beck
- Academic Cardiology Unit, National Heart and Lung Institute, Imperial College School of Medicine, London
| | - Nicholas A Flores
- Academic Cardiology Unit, National Heart and Lung Institute, Imperial College School of Medicine, London
- Author for correspondence:
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48
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Beauloye C, Marsin AS, Bertrand L, Krause U, Hardie DG, Vanoverschelde JL, Hue L. Insulin antagonizes AMP-activated protein kinase activation by ischemia or anoxia in rat hearts, without affecting total adenine nucleotides. FEBS Lett 2001; 505:348-52. [PMID: 11576526 DOI: 10.1016/s0014-5793(01)02788-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
AMP-activated protein kinase (AMPK) is known to be activated by phosphorylation on Thr172 in response to an increased AMP/ATP ratio. We report here that such an activation indeed occurred in anaerobic rat hearts and that it was antagonized (40-50%) when the hearts were pre-treated with 100 nM insulin. The effect of insulin (1) was blocked by wortmannin, an inhibitor of phosphatidylinositol-3-kinase; (2) only occurred when insulin was added before anoxia, suggesting a hierarchical control; (3) resulted in a decreased phosphorylation state of Thr172 in AMPK and (4) was unrelated to changes in the AMP/ATP ratio. This is the first demonstration that AMPK activity could be changed without a detectable change in the AMP/ATP ratio of the cardiac cell.
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Affiliation(s)
- C Beauloye
- Hormone and Metabolic Research Unit, Institute of Cellular Pathology, Brussels, Belgium
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49
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Golczak M, Kirilenko A, Bandorowicz-Pikula J, Pikula S. Conformational states of annexin VI in solution induced by acidic pH. FEBS Lett 2001; 496:49-54. [PMID: 11343705 DOI: 10.1016/s0014-5793(01)02402-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Acidic pH-induced folding of annexin (Anx)VI in solution was investigated in order to study the mechanism of formation of ion channels by the protein in membranes. Using 2-(p-toluidino)naphthalene-6-sulfonic acid as a hydrophobic probe, it was demonstrated that AnxVI exerts a large change in hydrophobicity at acidic pH. Moreover, circular dichroism spectra indicated that the native state of AnxVI changes at acidic pH towards a state characterized by a significant loss of alpha-helix content and appearance of new beta-structures. These changes are reversible upon an increase of pH. It is postulated that the structural folding of AnxVI could explain how a soluble protein may undergo transition into a molecule able to penetrate the membrane hydrophobic region. The physiological significance of these observations is discussed.
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Affiliation(s)
- M Golczak
- Department of Cellular Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
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