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Harold KM, Matsuzaki S, Pranay A, Loveland BL, Batushansky A, Mendez Garcia MF, Eyster C, Stavrakis S, Chiao YA, Kinter M, Humphries KM. Loss of Cardiac PFKFB2 Drives Metabolic, Functional, and Electrophysiological Remodeling in the Heart. J Am Heart Assoc 2024; 13:e033676. [PMID: 38533937 PMCID: PMC11179765 DOI: 10.1161/jaha.123.033676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 02/20/2024] [Indexed: 03/28/2024]
Abstract
BACKGROUND Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) is a critical glycolytic regulator responsible for upregulation of glycolysis in response to insulin and adrenergic signaling. PFKFB2, the cardiac isoform of PFK-2, is degraded in the heart in the absence of insulin signaling, contributing to diabetes-induced cardiac metabolic inflexibility. However, previous studies have not examined how the loss of PFKFB2 affects global cardiac metabolism and function. METHODS AND RESULTS To address this, we have generated a mouse model with a cardiomyocyte-specific knockout of PFKFB2 (cKO). Using 9-month-old cKO and control mice, we characterized the impacts of PFKFB2 on cardiac metabolism, function, and electrophysiology. cKO mice have a shortened life span of 9 months. Metabolically, cKO mice are characterized by increased glycolytic enzyme abundance and pyruvate dehydrogenase activity, as well as decreased mitochondrial abundance and beta oxidation, suggesting a shift toward glucose metabolism. This was supported by a decrease in the ratio of palmitoyl carnitine to pyruvate-dependent mitochondrial respiration in cKO relative to control animals. Metabolomic, proteomic, and Western blot data support the activation of ancillary glucose metabolism, including pentose phosphate and hexosamine biosynthesis pathways. Physiologically, cKO animals exhibited impaired systolic function and left ventricular dilation, represented by reduced fractional shortening and increased left ventricular internal diameter, respectively. This was accompanied by electrophysiological alterations including increased QT interval and other metrics of delayed ventricular conduction. CONCLUSIONS Loss of PFKFB2 results in metabolic remodeling marked by cardiac ancillary pathway activation. This could delineate an underpinning of pathologic changes to mechanical and electrical function in the heart.
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Affiliation(s)
- Kylene M. Harold
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
- Department of Biochemistry and Molecular PhysiologyUniversity of Oklahoma Health Sciences CenterOklahoma CityOKUSA
| | - Satoshi Matsuzaki
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
| | - Atul Pranay
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
| | - Brooke L. Loveland
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
| | - Albert Batushansky
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
- Ilse Katz Institute for Nanoscale Science & TechnologyBen‐Gurion University of the NegevBeer ShevaIsrael
| | - Maria F. Mendez Garcia
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
| | - Craig Eyster
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
| | - Stavros Stavrakis
- Department of Medicine, Section of Cardiovascular MedicineUniversity of Oklahoma Health Sciences CenterOklahoma CityOKUSA
| | - Ying Ann Chiao
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
- Department of Biochemistry and Molecular PhysiologyUniversity of Oklahoma Health Sciences CenterOklahoma CityOKUSA
| | - Michael Kinter
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
| | - Kenneth M. Humphries
- Aging and Metabolism Research Program, Oklahoma Medical Research FoundationOklahoma CityOKUSA
- Department of Biochemistry and Molecular PhysiologyUniversity of Oklahoma Health Sciences CenterOklahoma CityOKUSA
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Colosimo S, Mitra SK, Chaudhury T, Marchesini G. Insulin resistance and metabolic flexibility as drivers of liver and cardiac disease in T2DM. Diabetes Res Clin Pract 2023; 206:111016. [PMID: 37979728 DOI: 10.1016/j.diabres.2023.111016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/15/2023] [Accepted: 11/13/2023] [Indexed: 11/20/2023]
Abstract
Metabolic flexibility refers to the ability of tissues to adapt their use of energy sources according to substrate availability and energy demands. This review aims to disentangle the emerging mechanisms through which altered metabolic flexibility and insulin resistance promote NAFLD and heart disease progression. Insulin resistance and metabolic inflexibility are central drivers of hepatic and cardiac diseases in individuals with type 2 diabetes. Both play a critical role in the complex interaction between glucose and lipid metabolism. Disruption of metabolic flexibility results in hyperglycemia and abnormal lipid metabolism, leading to increased accumulation of fat in the liver, contributing to the development and progression of NAFLD. Similarly, insulin resistance affects cardiac glucose metabolism, leading to altered utilization of energy substrates and impaired cardiac function, and influence cardiac lipid metabolism, further exacerbating the progression of heart failure. Regular physical activity promotes metabolic flexibility by increasing energy expenditure and enabling efficient switching between different energy substrates. On the contrary, weight loss achieved through calorie restriction ameliorates insulin sensitivity without improving flexibility. Strategies that mimic the effects of physical exercise, such as pharmacological interventions or targeted lifestyle modifications, show promise in effectively treating both diabetes and NAFLD, finally reducing the risk of advanced liver disease.
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Affiliation(s)
- Santo Colosimo
- School of Nutrition Science, University of Milan, Milan, Italy
| | - Sandip Kumar Mitra
- Diabetes and Endocrinology Unit, Apollo Gleneagles Hospital, Kolkata, West Bengal, India
| | - Tirthankar Chaudhury
- Diabetes and Endocrinology Unit, Apollo Gleneagles Hospital, Kolkata, West Bengal, India
| | - Giulio Marchesini
- IRCCS-Azienda Ospedaliero-Universitaria di Bologna, Policlinico di Sant'Orsola, Bologna, Italy.
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Harold KM, Matsuzaki S, Pranay A, Loveland BL, Batushansky A, Mendez Garcia MF, Eyster C, Stavrakis S, Chiao YA, Kinter M, Humphries KM. Loss of cardiac PFKFB2 drives Metabolic, Functional, and Electrophysiological Remodeling in the Heart. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568379. [PMID: 38045353 PMCID: PMC10690253 DOI: 10.1101/2023.11.22.568379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Background Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) is a critical glycolytic regulator responsible for upregulation of glycolysis in response to insulin and adrenergic signaling. PFKFB2, the cardiac isoform of PFK-2, is degraded in the heart in the absence of insulin signaling, contributing to diabetes-induced cardiac metabolic inflexibility. However, previous studies have not examined how the loss of PFKFB2 affects global cardiac metabolism and function. Methods To address this, we have generated a mouse model with a cardiomyocyte-specific knockout of PFKFB2 (cKO). Using 9-month-old cKO and control (CON) mice, we characterized impacts of PFKFB2 on cardiac metabolism, function, and electrophysiology. Results cKO mice have a shortened lifespan of 9 months. Metabolically, cKO mice are characterized by increased glycolytic enzyme abundance and pyruvate dehydrogenase (PDH) activity, as well as decreased mitochondrial abundance and beta oxidation, suggesting a shift toward glucose metabolism. This was supported by a decrease in the ratio of palmitoyl carnitine to pyruvate-dependent mitochondrial respiration in cKO relative to CON animals. Metabolomic, proteomic, and western blot data support the activation of ancillary glucose metabolism, including pentose phosphate and hexosamine biosynthesis pathways. Physiologically, cKO animals exhibited impaired systolic function and left ventricular (LV) dilation, represented by reduced fractional shortening and increased LV internal diameter, respectively. This was accompanied by electrophysiological alterations including increased QT interval and other metrics of delayed ventricular conduction. Conclusions Loss of PFKFB2 results in metabolic remodeling marked by cardiac ancillary pathway activation. This could delineate an underpinning of pathologic changes to mechanical and electrical function in the heart. Clinical Perspective What is New?: We have generated a novel cardiomyocyte-specific knockout model of PFKFB2, the cardiac isoform of the primary glycolytic regulator Phosphofructokinase-2 (cKO).The cKO model demonstrates that loss of cardiac PFKFB2 drives metabolic reprogramming and shunting of glucose metabolites to ancillary metabolic pathways.The loss of cardiac PFKFB2 promotes electrophysiological and functional remodeling in the cKO heart.What are the Clinical Implications?: PFKFB2 is degraded in the absence of insulin signaling, making its loss particularly relevant to diabetes and the pathophysiology of diabetic cardiomyopathy.Changes which we observe in the cKO model are consistent with those often observed in diabetes and heart failure of other etiologies.Defining PFKFB2 loss as a driver of cardiac pathogenesis identifies it as a target for future investigation and potential therapeutic intervention.
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Hwang H, Liu R, Eldridge R, Hu X, Forghani P, Jones DP, Xu C. Chronic ethanol exposure induces mitochondrial dysfunction and alters gene expression and metabolism in human cardiac spheroids. ALCOHOL, CLINICAL & EXPERIMENTAL RESEARCH 2023; 47:643-658. [PMID: 36799338 PMCID: PMC10149610 DOI: 10.1111/acer.15026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/18/2023]
Abstract
BACKGROUND Chronic alcohol consumption in adults can induce various cardiac toxicities such as arrhythmias, cardiomyopathy, and heart failure. Prenatal alcohol exposure can increase the risk of developing congenital heart defects among offspring. Understanding the molecular mechanisms underlying long-term alcohol exposure-induced cardiotoxicity can help guide the development of therapeutic strategies. METHODS Cardiomyocytes derived from human-induced pluripotent stem cells (hiPSC-CMs) were engineered into cardiac spheroids and treated with clinically relevant concentrations of ethanol (17 and 50 mM) for 5 weeks. The cells were then analyzed for changes in mitochondrial features, transcriptomic and metabolomic profiles, and integrated omics outcomes. RESULTS Following chronic ethanol treatment of hiPSC-CMs, a decrease in mitochondrial membrane potential and respiration and changes in expression of mitochondrial function-related genes were observed. RNA-sequencing analysis revealed changes in various metabolic processes, heart development, response to hypoxia, and extracellular matrix-related activities. Metabolomic analysis revealed dysregulation of energy metabolism and increased metabolites associated with the upregulation of inflammation. Integrated omics analysis further identified functional subclusters and revealed potentially affected pathways associated with cardiac toxicities. CONCLUSION Chronic ethanol treatment of hiPSC-CMs resulted in overall decreased mitochondrial function, increased glycolysis, disrupted fatty acid oxidation, and impaired cardiac structural development.
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Affiliation(s)
- Hyun Hwang
- Department of Pediatrics, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Rui Liu
- Department of Pediatrics, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Ronald Eldridge
- Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, GA 30322, USA
| | - Xin Hu
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Parvin Forghani
- Department of Pediatrics, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Dean P. Jones
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Chunhui Xu
- Department of Pediatrics, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
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Cadour F, Thuny F, Sourdon J. New Insights in Early Detection of Anticancer Drug-Related Cardiotoxicity Using Perfusion and Metabolic Imaging. Front Cardiovasc Med 2022; 9:813883. [PMID: 35198613 PMCID: PMC8858802 DOI: 10.3389/fcvm.2022.813883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/06/2022] [Indexed: 12/16/2022] Open
Abstract
Cardio-oncology requires a good knowledge of the cardiotoxicity of anticancer drugs, their mechanisms, and their diagnosis for better management. Anthracyclines, anti-vascular endothelial growth factor (VEGF), alkylating agents, antimetabolites, anti-human epidermal growth factor receptor (HER), and receptor tyrosine kinase inhibitors (RTKi) are therapeutics whose cardiotoxicity involves several mechanisms at the cellular and subcellular levels. Current guidelines for anticancer drugs cardiotoxicity are essentially based on monitoring left ventricle ejection fraction (LVEF). However, knowledge of microvascular and metabolic dysfunction allows for better imaging assessment before overt LVEF impairment. Early detection of anticancer drug-related cardiotoxicity would therefore advance the prevention and patient care. In this review, we provide a comprehensive overview of the cardiotoxic effects of anticancer drugs and describe myocardial perfusion, metabolic, and mitochondrial function imaging approaches to detect them before over LVEF impairment.
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Affiliation(s)
- Farah Cadour
- Aix-Marseille Université, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Franck Thuny
- Aix-Marseille University, University Mediterranean Center of Cardio-Oncology, Unit of Heart Failure and Valvular Heart Diseases, Department of Cardiology, North Hospital, Assistance Publique - Hôpitaux de Marseille, Centre for CardioVascular and Nutrition Research (C2VN), Inserm 1263, Inrae 1260, Marseille, France
| | - Joevin Sourdon
- Aix-Marseille Université, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
- *Correspondence: Joevin Sourdon
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Heidary Moghaddam R, Samimi Z, Asgary S, Mohammadi P, Hozeifi S, Hoseinzadeh-Chahkandak F, Xu S, Farzaei MH. Natural AMPK Activators in Cardiovascular Disease Prevention. Front Pharmacol 2022; 12:738420. [PMID: 35046800 PMCID: PMC8762275 DOI: 10.3389/fphar.2021.738420] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/03/2021] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular diseases (CVD), as a life-threatening global disease, is receiving worldwide attention. Seeking novel therapeutic strategies and agents is of utmost importance to curb CVD. AMP-activated protein kinase (AMPK) activators derived from natural products are promising agents for cardiovascular drug development owning to regulatory effects on physiological processes and diverse cardiometabolic disorders. In the past decade, different therapeutic agents from natural products and herbal medicines have been explored as good templates of AMPK activators. Hereby, we overviewed the role of AMPK signaling in the cardiovascular system, as well as evidence implicating AMPK activators as potential therapeutic tools. In the present review, efforts have been made to compile and update relevant information from both preclinical and clinical studies, which investigated the role of natural products as AMPK activators in cardiovascular therapeutics.
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Affiliation(s)
- Reza Heidary Moghaddam
- Clinical Research Development Center, Imam Ali and Taleghani Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Zeinab Samimi
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Sedigheh Asgary
- Isfahan Cardiovascular Research Center, Cardiovascular Research Institute,.Isfahan University of Medical Sciences, Isfahan, Iran
| | - Pantea Mohammadi
- Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Soroush Hozeifi
- School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | | | - Suowen Xu
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Mohammad Hosein Farzaei
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran.,Medical Technology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Energy metabolism homeostasis in cardiovascular diseases. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2021; 18:1044-1057. [PMID: 35136399 PMCID: PMC8782763 DOI: 10.11909/j.issn.1671-5411.2021.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the general population. Energy metabolism disturbance is one of the early abnormalities in CVDs, such as coronary heart disease, diabetic cardiomyopathy, and heart failure. To explore the role of myocardial energy homeostasis disturbance in CVDs, it is important to understand myocardial metabolism in the normal heart and their function in the complex pathophysiology of CVDs. In this article, we summarized lipid metabolism/lipotoxicity and glucose metabolism/insulin resistance in the heart, focused on the metabolic regulation during neonatal and ageing heart, proposed potential metabolic mechanisms for cardiac regeneration and degeneration. We provided an overview of emerging molecular network among cardiac proliferation, regeneration, and metabolic disturbance. These novel targets promise a new era for the treatment of CVDs.
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Jin ES, Lee MH, Malloy CR. 13 C NMR of glutamate for monitoring the pentose phosphate pathway in myocardium. NMR IN BIOMEDICINE 2021; 34:e4533. [PMID: 33900680 DOI: 10.1002/nbm.4533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/05/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
After administration of 13 C-labeled glucose, the activity of the pentose phosphate pathway (PPP) is often assessed by the distribution of 13 C in lactate. However, in some tissues, such as the well-oxygenated heart, the concentration of lactate may be too low for convenient analysis by NMR. Here, we examined 13 C-labeled glutamate as an alternative biomarker of the PPP in the heart. Isolated rat hearts were perfused with media containing [2,3-13 C2 ]glucose and the tissue extracts were analyzed. Metabolism of [2,3-13 C2 ]glucose yields [1,2-13 C2 ]pyruvate via glycolysis and [2,3-13 C2 ]pyruvate via the PPP. Pyruvate is in exchange with lactate or is further metabolized to glutamate through pyruvate dehydrogenase and the TCA cycle. A doublet from [4,5-13 C2 ]glutamate, indicating flux through the PPP, was readily detected in 13 C NMR of heart extracts even when the corresponding doublet from [2,3-13 C2 ]lactate was minimal. Benfotiamine, known to induce the PPP, caused an increase in production of [4,5-13 C2 ]glutamate. In rats receiving [2,3-13 C2 ]glucose, brain extracts showed well-resolved signals from both [2,3-13 C2 ]lactate and [4,5-13 C2 ]glutamate in 13 C NMR spectra. Assessment of the PPP in the brain based on glutamate had a strong linear correlation with lactate-based assessment. In summary, 13 C NMR analysis of glutamate enabled detection of the low PPP activity in isolated hearts. This analyte is an alternative to lactate for monitoring the PPP with the use of [2,3-13 C2 ]glucose.
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Affiliation(s)
- Eunsook S Jin
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Min H Lee
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- VA North Texas Health Care System, Dallas, Texas, USA
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Hasan MT, Hassan M, Ahmed K, Islam MR, Islam K, Bhuyian T, Uddin MS, Paul BK. Network based study to explore genetic linkage between diabetes mellitus and myocardial ischemia: Bioinformatics approach. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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10
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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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Okawa Y, Hoshino A, Ariyoshi M, Kaimoto S, Tateishi S, Ono K, Uchihashi M, Iwai-Kanai E, Matoba S. Ablation of cardiac TIGAR preserves myocardial energetics and cardiac function in the pressure overload heart failure model. Am J Physiol Heart Circ Physiol 2019; 316:H1366-H1377. [DOI: 10.1152/ajpheart.00395.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite the advances in medical therapy, the morbidity and mortality of heart failure (HF) remain unacceptably high. HF results from reduced metabolism–contraction coupling efficiency, so the modulation of cardiac metabolism may be an effective strategy for therapeutic interventions. Tumor suppressor p53 (TP53) and its downstream target TP53-induced glycolysis and apoptosis regulator (TIGAR) are known to modulate cardiac metabolism and cell fate. To investigate TIGAR’s function in HF, we compared myocardial, metabolic, and functional outcomes between TIGAR knockout (TIGAR−/−) mice and wild-type (TIGAR+/+) mice subjected to chronic thoracic transverse aortic constriction (TAC), a pressure-overload HF model. In wild-type mice hearts, p53 and TIGAR increased markedly during HF development. Eight weeks after TAC surgery, the left ventricular (LV) dysfunction, fibrosis, oxidative damage, and myocyte apoptosis were significantly advanced in wild-type than in TIGAR−/− mouse heart. Further, myocardial high-energy phosphates in wild-type hearts were significantly decreased compared with those of TIGAR−/− mouse heart. Glucose oxidation and glycolysis rates were also reduced in isolated perfused wild-type hearts following TAC than those in TIGAR−/− hearts, which suggest that the upregulation of TIGAR in HF causes impaired myocardial energetics and function. The effects of TIGAR knockout on LV function were also replicated in tamoxifen (TAM)-inducible cardiac-specific TIGAR knockout mice ( TIGARflox/flox/Tg(Myh6-cre/Esr1) mice). The ablation of TIGAR during pressure-overload HF preserves myocardial function and energetics. Thus, cardiac TIGAR-targeted therapy to increase glucose metabolism will be a novel strategy for HF. NEW & NOTEWORTHY The present study is the first to demonstrate that TP53-induced glycolysis and apoptosis regulator (TIGAR) is upregulated in the myocardium during experimental heart failure (HF) in mice and that TIGAR knockout can preserve the heart function and myocardial energetics during HF. Reducing TIGAR to enhance myocardial glycolytic energy production is a promising therapeutic strategy for HF.
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Affiliation(s)
- Yoshifumi Okawa
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Atsushi Hoshino
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Makoto Ariyoshi
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Satoshi Kaimoto
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Shuhei Tateishi
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Kazunori Ono
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Motoki Uchihashi
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
| | - Eri Iwai-Kanai
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
- Faculty of Health Care, Tenri Health Care University, Nara, Japan
| | - Satoaki Matoba
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine Kawaramachi-Hirokoji, Kyoto, Japan
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AMP-Activated Protein Kinase (AMPK)-Dependent Regulation of Renal Transport. Int J Mol Sci 2018; 19:ijms19113481. [PMID: 30404151 PMCID: PMC6274953 DOI: 10.3390/ijms19113481] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/26/2018] [Accepted: 10/30/2018] [Indexed: 02/06/2023] Open
Abstract
AMP-activated kinase (AMPK) is a serine/threonine kinase that is expressed in most cells and activated by a high cellular AMP/ATP ratio (indicating energy deficiency) or by Ca2+. In general, AMPK turns on energy-generating pathways (e.g., glucose uptake, glycolysis, fatty acid oxidation) and stops energy-consuming processes (e.g., lipogenesis, glycogenesis), thereby helping cells survive low energy states. The functional element of the kidney, the nephron, consists of the glomerulus, where the primary urine is filtered, and the proximal tubule, Henle's loop, the distal tubule, and the collecting duct. In the tubular system of the kidney, the composition of primary urine is modified by the reabsorption and secretion of ions and molecules to yield final excreted urine. The underlying membrane transport processes are mainly energy-consuming (active transport) and in some cases passive. Since active transport accounts for a large part of the cell's ATP demands, it is an important target for AMPK. Here, we review the AMPK-dependent regulation of membrane transport along nephron segments and discuss physiological and pathophysiological implications.
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Karwi QG, Uddin GM, Ho KL, Lopaschuk GD. Loss of Metabolic Flexibility in the Failing Heart. Front Cardiovasc Med 2018; 5:68. [PMID: 29928647 PMCID: PMC5997788 DOI: 10.3389/fcvm.2018.00068] [Citation(s) in RCA: 243] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/18/2018] [Indexed: 12/15/2022] Open
Abstract
To maintain its high energy demand the heart is equipped with a highly complex and efficient enzymatic machinery that orchestrates ATP production using multiple energy substrates, namely fatty acids, carbohydrates (glucose and lactate), ketones and amino acids. The contribution of these individual substrates to ATP production can dramatically change, depending on such variables as substrate availability, hormonal status and energy demand. This "metabolic flexibility" is a remarkable virtue of the heart, which allows utilization of different energy substrates at different rates to maintain contractile function. In heart failure, cardiac function is reduced, which is accompanied by discernible energy metabolism perturbations and impaired metabolic flexibility. While it is generally agreed that overall mitochondrial ATP production is impaired in the failing heart, there is less consensus as to what actual switches in energy substrate preference occur. The failing heart shift toward a greater reliance on glycolysis and ketone body oxidation as a source of energy, with a decrease in the contribution of glucose oxidation to mitochondrial oxidative metabolism. The heart also becomes insulin resistant. However, there is less consensus as to what happens to fatty acid oxidation in heart failure. While it is generally believed that fatty acid oxidation decreases, a number of clinical and experimental studies suggest that fatty acid oxidation is either not changed or is increased in heart failure. Of importance, is that any metabolic shift that does occur has the potential to aggravate cardiac dysfunction and the progression of the heart failure. An increasing body of evidence shows that increasing cardiac ATP production and/or modulating cardiac energy substrate preference positively correlates with heart function and can lead to better outcomes. This includes increasing glucose and ketone oxidation and decreasing fatty acid oxidation. In this review we present the physiology of the energy metabolism pathways in the heart and the changes that occur in these pathways in heart failure. We also look at the interventions which are aimed at manipulating the myocardial metabolic pathways toward more efficient substrate utilization which will eventually improve cardiac performance.
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Affiliation(s)
| | | | | | - Gary D. Lopaschuk
- Cardiovascular Research Centre, University of Alberta, Edmonton, AB, Canada
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14
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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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15
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Smallwood HS, Duan S, Morfouace M, Rezinciuc S, Shulkin BL, Shelat A, Zink EE, Milasta S, Bajracharya R, Oluwaseum AJ, Roussel MF, Green DR, Pasa-Tolic L, Thomas PG. Targeting Metabolic Reprogramming by Influenza Infection for Therapeutic Intervention. Cell Rep 2018; 19:1640-1653. [PMID: 28538182 DOI: 10.1016/j.celrep.2017.04.039] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 03/07/2017] [Accepted: 04/13/2017] [Indexed: 01/24/2023] Open
Abstract
Influenza is a worldwide health and financial burden posing a significant risk to the immune-compromised, obese, diabetic, elderly, and pediatric populations. We identified increases in glucose metabolism in the lungs of pediatric patients infected with respiratory pathogens. Using quantitative mass spectrometry, we found metabolic changes occurring after influenza infection in primary human respiratory cells and validated infection-associated increases in c-Myc, glycolysis, and glutaminolysis. We confirmed these findings with a metabolic drug screen that identified the PI3K/mTOR inhibitor BEZ235 as a regulator of infectious virus production. BEZ235 treatment ablated the transient induction of c-Myc, restored PI3K/mTOR pathway homeostasis measured by 4E-BP1 and p85 phosphorylation, and reversed infection-induced changes in metabolism. Importantly, BEZ235 reduced infectious progeny but had no effect on the early stages of viral replication. BEZ235 significantly increased survival in mice, while reducing viral titer. We show metabolic reprogramming of host cells by influenza virus exposes targets for therapeutic intervention.
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Affiliation(s)
- Heather S Smallwood
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Susu Duan
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Marie Morfouace
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Svetlana Rezinciuc
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Barry L Shulkin
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Anang Shelat
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Erika E Zink
- Department of Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Sandra Milasta
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Resha Bajracharya
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Ajayi J Oluwaseum
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Martine F Roussel
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Ljiljana Pasa-Tolic
- Department of Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Paul G Thomas
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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16
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Sourdon J, Lager F, Viel T, Balvay D, Moorhouse R, Bennana E, Renault G, Tharaux PL, Dhaun N, Tavitian B. Cardiac Metabolic Deregulation Induced by the Tyrosine Kinase Receptor Inhibitor Sunitinib is rescued by Endothelin Receptor Antagonism. Theranostics 2017; 7:2757-2774. [PMID: 28824714 PMCID: PMC5562214 DOI: 10.7150/thno.19551] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/31/2017] [Indexed: 02/06/2023] Open
Abstract
The growing field of cardio-oncology addresses the side effects of cancer treatment on the cardiovascular system. Here, we explored the cardiotoxicity of the antiangiogenic therapy, sunitinib, in the mouse heart from a diagnostic and therapeutic perspective. We showed that sunitinib induces an anaerobic switch of cellular metabolism within the myocardium which is associated with the development of myocardial fibrosis and reduced left ventricular ejection fraction as demonstrated by echocardiography. The capacity of positron emission tomography with [18F]fluorodeoxyglucose to detect the changes in cardiac metabolism caused by sunitinib was dependent on fasting status and duration of treatment. Pan proteomic analysis in the myocardium showed that sunitinib induced (i) an early metabolic switch with enhanced glycolysis and reduced oxidative phosphorylation, and (ii) a metabolic failure to use glucose as energy substrate, similar to the insulin resistance found in type 2 diabetes. Co-administration of the endothelin receptor antagonist, macitentan, to sunitinib-treated animals prevented both metabolic defects, restored glucose uptake and cardiac function, and prevented myocardial fibrosis. These results support the endothelin system in mediating the cardiotoxic effects of sunitinib and endothelin receptor antagonism as a potential therapeutic approach to prevent cardiotoxicity. Furthermore, metabolic and functional imaging can monitor the cardiotoxic effects and the benefits of endothelin antagonism in a theranostic approach.
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Affiliation(s)
- Joevin Sourdon
- Paris Cardiovascular Research Center (PARCC); INSERM UMR970; Université Paris Descartes; Paris, France
| | - Franck Lager
- Institut Cochin, Université Paris Descartes, INSERM U1016, Paris 75014, France
| | - Thomas Viel
- Paris Cardiovascular Research Center (PARCC); INSERM UMR970; Université Paris Descartes; Paris, France
| | - Daniel Balvay
- Paris Cardiovascular Research Center (PARCC); INSERM UMR970; Université Paris Descartes; Paris, France
| | - Rebecca Moorhouse
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, Edinburgh, United Kingdom
| | - Evangeline Bennana
- Institut Cochin, Université Paris Descartes, INSERM U1016, Paris 75014, France
- 3P5 proteomics facility, Université Paris Descartes, Université Sorbonne Paris Cité, Paris, France
| | - Gilles Renault
- Institut Cochin, Université Paris Descartes, INSERM U1016, Paris 75014, France
| | - Pierre-Louis Tharaux
- Paris Cardiovascular Research Center (PARCC); INSERM UMR970; Université Paris Descartes; Paris, France
| | - Neeraj Dhaun
- University/British Heart Foundation Centre of Research Excellence, The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Bertrand Tavitian
- Paris Cardiovascular Research Center (PARCC); INSERM UMR970; Université Paris Descartes; Paris, France
- Service de Radiologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
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17
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Malagrino PA, Venturini G, Yogi PS, Dariolli R, Padilha K, Kiers B, Gois TC, Motta-Leal-Filho JM, Takimura CK, Girardi ACC, Carnevale FC, Canevarolo R, Malheiros DMAC, de Mattos Zeri AC, Krieger JE, Pereira AC. Metabolomic characterization of renal ischemia and reperfusion in a swine model. Life Sci 2016; 156:57-67. [DOI: 10.1016/j.lfs.2016.05.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 05/12/2016] [Accepted: 05/17/2016] [Indexed: 01/09/2023]
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18
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Bradley EA, Zhang L, Genders AJ, Richards SM, Rattigan S, Keske MA. Enhancement of insulin-mediated rat muscle glucose uptake and microvascular perfusion by 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside. Cardiovasc Diabetol 2015; 14:91. [PMID: 26194188 PMCID: PMC4509722 DOI: 10.1186/s12933-015-0251-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/30/2015] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Insulin-induced microvascular recruitment is important for optimal muscle glucose uptake. 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR, an activator of AMP-activated protein kinase), can also induce microvascular recruitment, at doses that do not acutely activate glucose transport in rat muscle. Whether low doses of AICAR can augment physiologic insulin action is unknown. In the present study we used the euglycemic hyperinsulinemic clamp to assess whether insulin action is augmented by low dose AICAR. METHODS Anesthetized rats were studied during saline infusion or euglycemic insulin (3 mU/kg/min) clamp for 2 h in the absence or presence of AICAR for the last hour (5 mg bolus followed by 3.75 mg/kg/min). Muscle glucose uptake (R'g) was determined radioisotopically with (14)C-2-deoxyglucose and muscle microvascular perfusion by contrast-enhanced ultrasound with microbubbles. RESULTS AICAR did not affect blood glucose, or lower leg R'g, although it significantly (p < 0.05) increased blood lactate levels and augmented muscle microvascular blood volume via a nitric oxide synthase dependent pathway. Insulin increased femoral blood flow, whole body glucose infusion rate (GIR), R'g, hindleg glucose uptake, and microvascular blood volume. Addition of AICAR during insulin infusion increased lactate production, further increased R'g in Type IIA (fast twitch oxidative) and IIB (fast twitch glycolytic) fiber containing muscles, and hindleg glucose uptake, but decreased R'g in the Type I (slow twitch oxidative) fiber muscle. AICAR also decreased GIR due to inhibition of insulin-mediated suppression of hepatic glucose output. AICAR augmented insulin-mediated microvascular perfusion. CONCLUSIONS AICAR, at levels that have no direct effect on muscle glucose uptake, augments insulin-mediated microvascular blood flow and glucose uptake in white fiber type muscles. Agents targeted to endothelial AMPK activation are promising insulin sensitizers, however, the decrease in GIR and the propensity to increase blood lactate cautions against AICAR as an acute insulin sensitizer.
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Affiliation(s)
- Eloise A Bradley
- Menzies Institute for Medical Research, University of Tasmania, Private Bag 23, Hobart, 7001, TAS, Australia.
| | - Lei Zhang
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.
| | - Amanda J Genders
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, VIC, Australia.
| | | | - Stephen Rattigan
- Menzies Institute for Medical Research, University of Tasmania, Private Bag 23, Hobart, 7001, TAS, Australia.
| | - Michelle A Keske
- Menzies Institute for Medical Research, University of Tasmania, Private Bag 23, Hobart, 7001, TAS, Australia.
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19
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Pashaj A, Xia M, Moreau R. α-Lipoic acid as a triglyceride-lowering nutraceutical. Can J Physiol Pharmacol 2015; 93:1029-41. [PMID: 26235242 DOI: 10.1139/cjpp-2014-0480] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Considering the current obesity epidemic in the United States (>100 million adults are overweight or obese), the prevalence of hypertriglyceridemia is likely to grow beyond present statistics of ∼30% of the population. Conventional therapies for managing hypertriglyceridemia include lifestyle modifications such as diet and exercise, pharmacological approaches, and nutritional supplements. It is critically important to identify new strategies that would be safe and effective in lowering hypertriglyceridemia. α-Lipoic acid (LA) is a naturally occurring enzyme cofactor found in the human body in small quantities. A growing body of evidence indicates a role of LA in ameliorating metabolic dysfunction and lipid anomalies primarily in animals. Limited human studies suggest LA is most efficacious in situations where blood triglycerides are markedly elevated. LA is commercially available as dietary supplements and is clinically shown to be safe and effective against diabetic polyneuropathies. LA is described as a potent biological antioxidant, a detoxification agent, and a diabetes medicine. Given its strong safety record, LA may be a useful nutraceutical, either alone or in combination with other lipid-lowering strategies, when treating severe hypertriglyceridemia and diabetic dyslipidemia. This review examines the current evidence regarding the use of LA as a means of normalizing blood triglycerides. Also presented are the leading mechanisms of action of LA on triglyceride metabolism.
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Affiliation(s)
- Anjeza Pashaj
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.,Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Mengna Xia
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.,Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Régis Moreau
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.,Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
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20
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Han J, Yi J, Liang F, Jiang B, Xiao Y, Gao S, Yang N, Hu H, Xie WF, Chen W. X-3, a mangiferin derivative, stimulates AMP-activated protein kinase and reduces hyperglycemia and obesity in db/db mice. Mol Cell Endocrinol 2015; 405:63-73. [PMID: 25681564 DOI: 10.1016/j.mce.2015.02.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 01/12/2015] [Accepted: 02/06/2015] [Indexed: 12/19/2022]
Abstract
Diabetes mellitus is a major health concern, affecting nearly 10% of the population. Here we describe a potential novel therapeutic agent for this disease, X-3, a derivative of mangiferin. Therapeutic administration of X-3 significantly and dose-dependently reduced plasma glucose and triglycerides in db/db mice following 8 week-treatments. Treatment with X-3 dose-dependently increased the number of insulin-positive β-cell mass. Importantly, X-3 did not cause any death or signs of toxicity in acute toxicity studies. Study of mechanism of action revealed that X-3 increased glucose uptake in parallel with increased phosphorylation of AMP-activated protein kinase (AMPK) in 3T3-L1 cells. It activates AMPK in both LKB1-dependent and -independent manner. Furthermore, administration of X-3 resulted in activation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC) in the hypothalamus, liver, muscle and adipose tissues of C57BL/6 mice. An 80 mg/kg X-3 was more potent than metformin at 500 mg/kg in the hypothalamus, and interscapular fat tissues, potent than MF at the same dose in the liver. Thus, we conclude that X-3 is a promising new class of AMPK activating drug, and can potentially be used in the treatment of type 2 diabetes.
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Affiliation(s)
- Jun Han
- Department of Gastroenterology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Jia Yi
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Fengying Liang
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Bo Jiang
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Ying Xiao
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Shouhong Gao
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Na Yang
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Honggang Hu
- Department of Organic Chemistry, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Wei-Fen Xie
- Department of Gastroenterology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Wansheng Chen
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, China.
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21
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Abstract
The heart is a very special organ in the body and has a high requirement for metabolism due to its constant workload. As a consequence, to provide a consistent and sufficient energy a high steady-state demand of metabolism is required by the heart. When delicately balanced mechanisms are changed by physiological or pathophysiological conditions, the whole system's homeostasis will be altered to a new balance, which contributes to the pathologic process. So it is no wonder that almost every heart disease is related to metabolic shift. Furthermore, aging is also found to be related to the reduction in mitochondrial function, insulin resistance, and dysregulated intracellular lipid metabolism. Adenosine monophosphate-activated protein kinase (AMPK) functions as an energy sensor to detect intracellular ATP/AMP ratio and plays a pivotal role in intracellular adaptation to energy stress. During different pathology (like myocardial ischemia and hypertension), the activation of cardiac AMPK appears to be essential for repairing cardiomyocyte's function by accelerating ATP generation, attenuating ATP depletion, and protecting the myocardium against cardiac dysfunction and apoptosis. In this overview, we will talk about the normal heart's metabolism, how metabolic shifts during aging and different pathologies, and how AMPK regulates metabolic changes during these conditions.
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Affiliation(s)
- Yina Ma
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, NY 14214
| | - Ji Li
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, NY 14214
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22
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Al Hasawi N, Alkandari MF, Luqmani YA. Phosphofructokinase: a mediator of glycolytic flux in cancer progression. Crit Rev Oncol Hematol 2014; 92:312-21. [PMID: 24910089 DOI: 10.1016/j.critrevonc.2014.05.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 04/10/2014] [Accepted: 05/13/2014] [Indexed: 01/07/2023] Open
Abstract
In view of the current limitations of cancer chemotherapy, there has been resurgent interest in re-visiting glycolysis to determine whether tumors could be killed by energy deprivation rather than solely by strategies to inhibit proliferation. Cancer cells exhibit a uniquely high rate of glucose utilization, converting it into lactate whose export subsequently creates an acidic extracellular environment that is thought to promote invasion and metastasis, in preference to its complete oxidation even in the presence of adequate oxygen supply. Reductive analysis of each step of glycolysis shows that, of the three rate limiting enzymes of the pathway, isoforms of phosphofructokinase may afford the greatest opportunity as targets to deprive cancer cells from essential energy and substrates for macromolecular synthesis for proliferation while allowing normal cells to survive. Strategies discussed include restricting the substrate for this enzyme. While prospects for monotherapy with glycolytic inhibitors are poor, combination therapy may be productive.
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Affiliation(s)
- Nada Al Hasawi
- Faculty of Pharmacy, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
| | - Mariam F Alkandari
- Faculty of Pharmacy, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
| | - Yunus A Luqmani
- Faculty of Pharmacy, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
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23
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Warmoes MO, Locasale JW. Heterogeneity of glycolysis in cancers and therapeutic opportunities. Biochem Pharmacol 2014; 92:12-21. [PMID: 25093285 PMCID: PMC4254151 DOI: 10.1016/j.bcp.2014.07.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/21/2014] [Accepted: 07/21/2014] [Indexed: 12/19/2022]
Abstract
Upregulated glycolysis, both in normoxic and hypoxic environments, is a nearly universal trait of cancer cells. The enormous difference in glucose metabolism offers a target for therapeutic intervention with a potentially low toxicity profile. The past decade has seen a steep rise in the development and clinical assessment of small molecules that target glycolysis. The enzymes in glycolysis have a highly heterogeneous nature that allows for the different bioenergetic, biosynthetic, and signaling demands needed for various tissue functions. In cancers, these properties enable them to respond to the variable requirements of cell survival, proliferation and adaptation to nutrient availability. Heterogeneity in glycolysis occurs through the expression of different isoforms, posttranslational modifications that affect the kinetic and regulatory properties of the enzyme. In this review, we will explore this vast heterogeneity of glycolysis and discuss how this information might be exploited to better target glucose metabolism and offer possibilities for biomarker development.
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Affiliation(s)
- Marc O Warmoes
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, United States
| | - Jason W Locasale
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, United States.
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24
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Vaillant F, Lauzier B, Poirier I, Gélinas R, Rivard ME, Robillard Frayne I, Thorin E, Des Rosiers C. Mouse strain differences in metabolic fluxes and function of ex vivo working hearts. Am J Physiol Heart Circ Physiol 2013; 306:H78-87. [PMID: 24186097 DOI: 10.1152/ajpheart.00465.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In mice, genetic background is known to influence various parameters, including cardiac function. Its impact on cardiac energy substrate metabolism-a factor known to be closely related to function and contributes to disease development-is, however, unclear. This was examined in this study. In commonly used control mouse substrains SJL/JCrNTac, 129S6/SvEvTac, C57Bl/6J, and C57Bl/6NCrl, we assessed the functional and metabolic phenotypes of 3-mo-old working mouse hearts perfused ex vivo with physiological concentrations of (13)C-labeled carbohydrates (CHO) and a fatty acid (FA). Marked variations in various functional and metabolic flux parameters were observed among all mouse substrains, although the pattern observed differed for these parameters. For example, among all strains, C57Bl/6NCrl hearts had a greater cardiac output (+1.7-fold vs. SJL/JCrNTac and C57Bl/6J; P < 0.05), whereas at the metabolic level, 129S6/SvEvTac hearts stood out by displaying (vs. all 3 strains) a striking shift from exogenous FA (~-3.5-fold) to CHO oxidation as well as increased glycolysis (+1.7-fold) and FA incorporation into triglycerides (+2-fold). Correlation analyses revealed, however, specific linkages between 1) glycolysis, FA oxidation, and pyruvate metabolism and 2) cardiac work, oxygen consumption with heart rate, respectively. This implies that any genetically determined factors affecting a given metabolic flux parameter may impact on the associated functional parameters. Our results emphasize the importance of selecting the appropriate control strain for cardiac metabolic studies using transgenic mice, a factor that has often been neglected. Understanding the molecular mechanisms underlying the diversity of strain-specific cardiac metabolic and functional profiles, particularly the 129S6/SvEvTac, may ultimately disclose new specific metabolic targets for interventions in heart disease.
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Affiliation(s)
- Fanny Vaillant
- Departments of Nutrition, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada; and
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25
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Novellasdemunt L, Tato I, Navarro-Sabate A, Ruiz-Meana M, Méndez-Lucas A, Perales JC, Garcia-Dorado D, Ventura F, Bartrons R, Rosa JL. Akt-dependent activation of the heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB2) isoenzyme by amino acids. J Biol Chem 2013; 288:10640-51. [PMID: 23457334 PMCID: PMC3624444 DOI: 10.1074/jbc.m113.455998] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/01/2013] [Indexed: 02/03/2023] Open
Abstract
Reciprocal regulation of metabolism and signaling allows cells to modulate their activity in accordance with their metabolic resources. Thus, amino acids could activate signal transduction pathways that control cell metabolism. To test this hypothesis, we analyzed the effect of amino acids on fructose-2,6-bisphosphate (Fru-2,6-P2) metabolism. We demonstrate that amino acids increase Fru-2,6-P2 concentration in HeLa and in MCF7 human cells. In conjunction with this, 6-phosphofructo-2-kinase activity, glucose uptake, and lactate concentration were increased. These data correlate with the specific phosphorylation of heart 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB2) isoenzyme at Ser-483. This activation was mediated by the PI3K and p38 signaling pathways. Furthermore, Akt inactivation blocked PFKFB2 phosphorylation and Fru-2,6-P2 production, thereby suggesting that the above signaling pathways converge at Akt kinase. In accordance with these results, kinase assays showed that amino acid-activated Akt phosphorylated PFKFB2 at Ser-483 and that knockdown experiments confirmed that the increase in Fru-2,6-P2 concentration induced by amino acids was due to PFKFB2. In addition, similar effects on Fru-2,6-P2 metabolism were observed in freshly isolated rat cardiomyocytes treated with amino acids, which indicates that these effects are not restricted to human cancer cells. In these cardiomyocytes, the glucose consumption and the production of lactate and ATP suggest an increase of glycolytic flux. Taken together, these results demonstrate that amino acids stimulate Fru-2,6-P2 synthesis by Akt-dependent PFKFB2 phosphorylation and activation and show how signaling and metabolism are inextricably linked.
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Affiliation(s)
- Laura Novellasdemunt
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - Irantzu Tato
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - Aurea Navarro-Sabate
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - Marisol Ruiz-Meana
- the Laboratory of Experimental Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona 08035, Spain
| | - Andrés Méndez-Lucas
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - Jose Carlos Perales
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - David Garcia-Dorado
- the Laboratory of Experimental Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona 08035, Spain
| | - Francesc Ventura
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - Ramon Bartrons
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
| | - Jose Luis Rosa
- From the Departament de Ciències Fisiològiques II, Campus de Bellvitge, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain and
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Nagendran J, Waller TJ, Dyck JRB. AMPK signalling and the control of substrate use in the heart. Mol Cell Endocrinol 2013; 366:180-93. [PMID: 22750050 DOI: 10.1016/j.mce.2012.06.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/29/2012] [Accepted: 06/21/2012] [Indexed: 12/21/2022]
Abstract
All mammalian cells rely on adenosine triphosphate (ATP) to maintain function and for survival. The heart has the highest basal ATP demand of any organ due to the necessity for continuous contraction. As such, the ability of the cardiomyocyte to monitor cellular energy status and adapt the supply of substrates to match the energy demand is crucial. One important serine/threonine protein kinase that monitors cellular energy status in the heart is adenosine monophosphate activated protein kinase (AMPK). AMPK is also a key enzyme that controls multiple catabolic and anabolic biochemical pathways in the heart and indirectly plays a crucial role in regulating cardiac function in both physiological and pathophysiological conditions. Herein, we review the involvement of AMPK in myocardial fatty acid and glucose transport and utilization, as it relates to basal cardiac function. We also assess the literature amassed on cardiac AMPK and discuss the controversies surrounding the role of AMPK in physiological and pathophysiological processes in the heart. The work reviewed herein also emphasizes areas that require further investigation for the purpose of eventually translating this information into improved patient care.
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Affiliation(s)
- Jeevan Nagendran
- Cardiovascular Research Centre, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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Wang J, Xu J, Wang Q, Brainard RE, Watson LJ, Jones SP, Epstein PN. Reduced cardiac fructose 2,6 bisphosphate increases hypertrophy and decreases glycolysis following aortic constriction. PLoS One 2013; 8:e53951. [PMID: 23308291 PMCID: PMC3538739 DOI: 10.1371/journal.pone.0053951] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 12/04/2012] [Indexed: 11/19/2022] Open
Abstract
This study was designed to test whether reduced levels of cardiac fructose-2,6-bisphosphate (F-2,6-P2) exacerbates cardiac damage in response to pressure overload. F-2,6-P2 is a positive regulator of the glycolytic enzyme phosphofructokinase. Normal and Mb transgenic mice were subject to transverse aortic constriction (TAC) or sham surgery. Mb transgenic mice have reduced F-2,6-P2 levels, due to cardiac expression of a transgene for a mutant, kinase deficient form of the enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) which controls the level of F-2,6-P2. Thirteen weeks following TAC surgery, glycolysis was elevated in FVB, but not in Mb, hearts. Mb hearts were markedly more sensitive to TAC induced damage. Echocardiography revealed lower fractional shortening in Mb-TAC mice as well as larger left ventricular end diastolic and end systolic diameters. Cardiac hypertrophy and pulmonary congestion were more severe in Mb-TAC mice as indicated by the ratios of heart and lung weight to tibia length. Expression of α-MHC RNA was reduced more in Mb-TAC hearts than in FVB-TAC hearts. TAC produced a much greater increase in fibrosis of Mb hearts and this was accompanied by 5-fold more collagen 1 RNA expression in Mb-TAC versus FVB-TAC hearts. Mb-TAC hearts had the lowest phosphocreatine to ATP ratio and the most oxidative stress as indicated by higher cardiac content of 4-hydroxynonenal protein adducts. These results indicate that the heart’s capacity to increase F-2,6-P2 during pressure overload elevates glycolysis which is beneficial for reducing pressure overload induced cardiac hypertrophy, dysfunction and fibrosis.
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Affiliation(s)
- Jianxun Wang
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, United States of America
| | - Jianxiang Xu
- Department of Pediatrics, University of Louisville, Louisville, Kentucky, United States of America
| | - Qianwen Wang
- Department of Physiology, University of Louisville, Louisville, Kentucky, United States of America
| | - Robert E. Brainard
- Department of Physiology, University of Louisville, Louisville, Kentucky, United States of America
- Institute of Molecular Cardiology, University of Louisville, Louisville, Kentucky, United States of America
| | - Lewis J. Watson
- Department of Physiology, University of Louisville, Louisville, Kentucky, United States of America
- Institute of Molecular Cardiology, University of Louisville, Louisville, Kentucky, United States of America
| | - Steven P. Jones
- Department of Physiology, University of Louisville, Louisville, Kentucky, United States of America
- Institute of Molecular Cardiology, University of Louisville, Louisville, Kentucky, United States of America
| | - Paul N. Epstein
- Department of Pediatrics, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail:
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Bieri M, Mobbs JI, Koay A, Louey G, Mok YF, Hatters DM, Park JT, Park KH, Neumann D, Stapleton D, Gooley PR. AMP-activated protein kinase β-subunit requires internal motion for optimal carbohydrate binding. Biophys J 2012; 102:305-14. [PMID: 22339867 DOI: 10.1016/j.bpj.2011.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 12/05/2011] [Accepted: 12/09/2011] [Indexed: 01/01/2023] Open
Abstract
AMP-activated protein kinase interacts with oligosaccharides and glycogen through the carbohydrate-binding module (CBM) containing the β-subunit, for which there are two isoforms (β(1) and β(2)). Muscle-specific β(2)-CBM, either as an isolated domain or in the intact enzyme, binds carbohydrates more tightly than the ubiquitous β(1)-CBM. Although residues that contact carbohydrate are strictly conserved, an additional threonine in a loop of β(2)-CBM is concurrent with an increase in flexibility in β(2)-CBM, which may account for the affinity differences between the two isoforms. In contrast to β(1)-CBM, unbound β(2)-CBM showed microsecond-to-millisecond motion at the base of a β-hairpin that contains residues that make critical contacts with carbohydrate. Upon binding to carbohydrate, similar microsecond-to-millisecond motion was observed in this β-hairpin and the loop that contains the threonine insertion. Deletion of the threonine from β(2)-CBM resulted in reduced carbohydrate affinity. Although motion was retained in the unbound state, a significant loss of motion was observed in the bound state of the β(2)-CBM mutant. Insertion of a threonine into the background of β(1)-CBM resulted in increased ligand affinity and flexibility in these loops when bound to carbohydrate. However, these mutations indicate that the additional threonine is not solely responsible for the differences in carbohydrate affinity and protein dynamics. Nevertheless, these results suggest that altered protein dynamics may contribute to differences in the ligand affinity of the two naturally occurring CBM isoforms.
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Affiliation(s)
- Michael Bieri
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Australia
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5'-AMP-activated protein kinase is inactivated by adrenergic signalling in adult cardiac myocytes. Biosci Rep 2012; 32:197-213. [PMID: 21851339 DOI: 10.1042/bsr20110076] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In adult rat cardiac myocytes adrenaline decreased AMPK (AMP-activated protein kinase) activity with a half-time of approximately 4 min, decreased phosphorylation of AMPK (α-Thr172) and decreased phosphorylation of ACC (acetyl-CoA carboxylase). Inactivation of AMPK by adrenaline was through both α1- and β-ARs (adrenergic receptors), but did not involve cAMP or calcium signalling, was not blocked by the PKC (protein kinase C) inhibitor BIM I (bisindoylmaleimide I), by the ERK (extracellular-signal-regulated kinase) cascade inhibitor U0126 or by PTX (pertussis toxin). Adrenaline caused no measurable change in LKB1 activity. Adrenaline decreased AMPK activity through a process that was distinct from AMPK inactivation in response to insulin or PMA. Neither adrenaline nor PMA altered the myocyte AMP:ATP ratio although the adrenaline effect was attenuated by oligomycin and by AICAR (5-amino-4-imidazolecarboxamide-1-β-D-ribofuranoside), agents that mimic 'metabolic stress'. Inactivation of AMPK by adrenaline was abolished by 1 μM okadaic acid suggesting that activation of PP2A (phosphoprotein phosphatase 2A) might mediate the adrenaline effect. However, no change in PP2A activity was detected in myocyte extracts. Adrenaline increased phosphorylation of the AMPK β-subunit in vitro but there was no detectable change in vivo in phosphorylation of previously identified AMPK sites (β-Ser24, β-Ser108 or β-Ser182) suggesting that another site(s) is targeted.
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de Oliveira UO, Belló-Kein A, de Oliveira ÁR, Kuchaski LC, Machado UF, Irigoyen MC, Schaan BD. Insulin alone or with captopril: effects on signaling pathways (AKT and AMPK) and oxidative balance after ischemia-reperfusion in isolated hearts. Fundam Clin Pharmacol 2011; 26:679-89. [PMID: 22029532 DOI: 10.1111/j.1472-8206.2011.00995.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Insulin and the inhibition of the renin-angiotensin system have independent benefits for ischemia-reperfusion injury, but their combination has not been tested. Our aim was to evaluate the effects of insulin+captopril on insulin/angiotensin signaling pathways and cardiac function in the isolated heart subjected to ischemia-reperfusion. Isolated hearts were perfused (Langendorff technique) with Krebs-Henseleit (KH) buffer for 25 min. Global ischemia was induced (20 min), followed by reperfusion (30 min) with KH (group KH), KH+angiotensin-I (group A), KH+angiotensin-I+captopril (group AC), KH+insulin (group I), KH+insulin+angiotensin-I (group IA), or KH+insulin+angiotensin-I+captopril (group IAC). Group A had a 24% reduction in developed pressure and an increase in end-diastolic pressure vs. baseline, effects that were reverted in groups AC, IA, and IAC. The phosphorylation of protein kinase B (AKT) was higher in groups I and IA vs. groups KH and A. The phosphorylation of AMP-activated protein kinase (AMPK) was ∼31% higher in groups I, IA, and IAC vs. groups KH, A, and AC. The tert-butyl hydroperoxide (tBOOH)-induced chemiluminescence was lower (∼2.2 times) in all groups vs. group KH and was ∼35% lower in group IA vs. group A. Superoxide dismutase content was lower in groups A, AC, and IAC vs. group KH. Catalase activity was ∼28% lower in all groups (except group IA) vs. group KH. During reperfusion of the ischemic heart, insulin activates the AKT and AMPK pathways and inhibits the deleterious effects of angiotensin-I perfusion on SOD expression and cardiac function. The addition of captopril does not potentiate these effects.
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Protective effects of erythropoietin on myocardial infarction in rats: the role of AMP-activated protein kinase signaling pathway. Am J Med Sci 2011; 342:153-9. [PMID: 21415704 DOI: 10.1097/maj.0b013e318210041d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Erythropoietin (EPO) has protective effects on myocardial infarction (MI). This study was to test whether EPO administrated after MI is as effective as EPO administrated before MI and to determine the role of AMP-activated protein kinase (AMPK) in the cardioprotective effects of EPO. Recombinant human EPO (5000 IU/kg) was intraperitoneally injected 12 hours before MI (pretreatment) or 30 minutes after MI (posttreatment). The levels of serum enzymes were assayed at 24 and 72 hours after MI. The infarct size was determined by nitro blue tetrazolium staining. The microarchitecture damages were evaluated by electron microscopy. EPO receptor messenger RNA and protein levels were determined by RT-PCR and immunohistochemistry, respectively. Activation of AMPK and nuclear factor kappa B was determined by immunoblotting. An AMPK-specific inhibitor, compound C, was used to inhibit AMPK activation in vivo. The authors found that both pretreatment and posttreatment of EPO successfully attenuated the serum enzyme levels, reduced the infarct size and ameliorated the microarchitecture damage. Moreover, both pretreatment and posttreatment of EPO decreased the EPO receptor messenger RNA and protein expressions, which were up-regulated in MI. More importantly, under MI conditions, EPO further increased the phosphorylation of AMPK and suppressed the activation of nuclear factor kappa B. Moreover, when AMPK was blocked by compound C, the cardioprotective effect of EPO was significantly attenuated (P < 0.01). Thus, this study demonstrates that both pretreatment and posttreatment of EPO are cardioprotective in an AMPK-dependent manners, providing the first evidence that the AMPK signaling pathway is involved in the cardioprotective effects of EPO.
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Abstract
Cardiovascular diseases remain the leading cause of mortality worldwide. Recent studies of AMP-activated protein kinase (AMPK), a highly conserved sensor of cellular energy status, suggest that there might be therapeutic value in targeting the AMPK signaling pathway. AMPK is found in most mammalian tissues, including those of the cardiovascular system. As cardiovascular diseases are typically associated with blood flow occlusion and blood occlusion may induce rapid energy deficit, AMPK activation may occur during the early phase upon nutrient deprivation in cardiovascular organs. Therefore, investigation of AMPK in cardiovascular organs may help us to understand the pathophysiology of defence mechanisms in these organs. Recent studies have provided proof of concept for the idea that AMPK is protective in heart as well as in vascular endothelial and smooth muscle cells. Moreover, dysfunction of the AMPK signalling pathway is involved in the genesis and development of various cardiovascular diseases, including atherosclerosis, hypertension and stroke. The roles of AMPK in the cardiovascular system, as they are currently understood, will be presented in this review. The interaction between AMPK and other cardiovascular signalling pathways such as nitric oxide signalling is also discussed.
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Affiliation(s)
- Qiang Xu
- Department of Geriatrics, Southwest Hospital, Third Military Medical University, Chongqing, China
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Yu Y, Clippinger AJ, Alwine JC. Viral effects on metabolism: changes in glucose and glutamine utilization during human cytomegalovirus infection. Trends Microbiol 2011; 19:360-7. [PMID: 21570293 DOI: 10.1016/j.tim.2011.04.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 04/06/2011] [Accepted: 04/12/2011] [Indexed: 12/21/2022]
Abstract
Human cytomegalovirus (HCMV) infection causes dramatic alterations of intermediary metabolism, similar to those found in tumor cells. In infected cells, glucose carbon is not completely broken down by the tricarboxylic acid (TCA) cycle for energy; instead, it is used biosynthetically. This process requires increased glucose uptake, increased glycolysis and the diversion of glucose carbon, in the form of citrate, from the TCA cycle for use in HCMV-induced fatty acid biosynthesis. The diversion of citrate from the TCA cycle (cataplerosis) requires induction of enzymes to promote glutaminolysis, the conversion of glutamine to α-ketoglutarate to maintain the TCA cycle (anaplerosis) and ATP production. Such changes could result in heretofore uncharacterized pathogenesis, potentially implicating HCMV as a subtle cofactor in many maladies, including oncogenesis. Recognition of the effects of HCMV, and other viruses, on host cell metabolism will provide new understanding of viral pathogenesis and novel avenues for antiviral therapy.
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Affiliation(s)
- Yongjun Yu
- Department of Cancer Biology, Abramson Family Cancer Research Institute, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Two ubiquitin ligases, APC/C-Cdh1 and SKP1-CUL1-F (SCF)-beta-TrCP, sequentially regulate glycolysis during the cell cycle. Proc Natl Acad Sci U S A 2011; 108:5278-83. [PMID: 21402913 DOI: 10.1073/pnas.1102247108] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
During cell proliferation, the abundance of the glycolysis-promoting enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, isoform 3 (PFKFB3), is controlled by the ubiquitin ligase APC/C-Cdh1 via a KEN box. We now demonstrate in synchronized HeLa cells that PFKFB3, which appears in mid-to-late G1, is essential for cell division because its silencing prevents progression into S phase. In cells arrested by glucose deprivation, progression into S phase after replacement of glucose occurs only when PFKFB3 is present or is substituted by the downstream glycolytic enzyme 6-phosphofructo-1-kinase. PFKFB3 ceases to be detectable during late G1/S despite the absence of Cdh1; this disappearance is prevented by proteasomal inhibition. PFKFB3 contains a DSG box and is therefore a potential substrate for SCF-β-TrCP, a ubiquitin ligase active during S phase. In synchronized HeLa cells transfected with PFKFB3 mutated in the KEN box, the DSG box, or both, we established the breakdown routes of the enzyme at different stages of the cell cycle and the point at which glycolysis is enhanced. Thus, the presence of PFKFB3 is tightly controlled to ensure the up-regulation of glycolysis at a specific point in G1. We suggest that this up-regulation of glycolysis and its associated events represent the nutrient-sensitive restriction point in mammalian cells.
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Rotte A, Pasham V, Eichenmüller M, Bhandaru M, Föller M, Lang F. Upregulation of Na+/H+ exchanger by the AMP-activated protein kinase. Biochem Biophys Res Commun 2010; 398:677-82. [PMID: 20609358 DOI: 10.1016/j.bbrc.2010.06.135] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 06/30/2010] [Indexed: 11/26/2022]
Abstract
AMP-activated protein kinase (AMPK) is activated upon energy depletion and serves to restore energy balance by stimulating energy production and limiting energy utilization. Specifically, it enhances cellular glucose uptake by stimulating GLUT and SGLT1 and glucose utilization by stimulating glycolysis. During O(2) deficiency glycolytic degradation of glucose leads to formation of lactate and H(+), thus imposing an acid load to the energy-deficient cell. Cellular acidification inhibits glycolysis and thus impedes glucose utilization. Maintenance of glycolysis thus requires cellular H(+) export. The present study explored whether AMPK influences Na(+)/H(+) exchanger (NHE) activity and/or Na(+)-independent acid extrusion. NHE1 expression was determined by RT-PCR and Western blotting. Cytosolic pH (pH(i)) was estimated utilizing BCECF fluorescence and Na(+)/H(+) exchanger activity from the Na(+)-dependent re-alkalinization (DeltapH(i)) after an ammonium pulse. As a result, human embryonic kidney (HEK) cells express NHE1. The pH(i) and DeltapH(i) in those cells were significantly increased by treatment with AMPK stimulator AICAR (1mM) and significantly decreased by AMPK inhibitor compound C (10 microM). The effect of AICAR on pH(i) and DeltapH(i) was blunted in the presence of the Na(+)/H(+) exchanger inhibitor cariporide (10microM), but not by the H(+) ATPase inhibitor bafilomycin (10nM). AICAR significantly enhanced lactate formation, an effect significantly blunted in the presence of cariporide. These observations disclose a novel function of AMPK, i.e. regulation of cytosolic pH.
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Affiliation(s)
- Anand Rotte
- Department of Physiology, University of Tübingen, Gmelinstrasse 5, D72076 Tübingen, Germany.
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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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Karakikes I, Kim M, Hadri L, Sakata S, Sun Y, Zhang W, Chemaly ER, Hajjar RJ, Lebeche D. Gene remodeling in type 2 diabetic cardiomyopathy and its phenotypic rescue with SERCA2a. PLoS One 2009; 4:e6474. [PMID: 19649297 PMCID: PMC2714457 DOI: 10.1371/journal.pone.0006474] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 07/03/2009] [Indexed: 12/31/2022] Open
Abstract
Background/Aim Diabetes-associated myocardial dysfunction results in altered gene expression in the heart. We aimed to investigate the changes in gene expression profiles accompanying diabetes-induced cardiomyopathy and its phenotypic rescue by restoration of SERCA2a expression. Methods/Results Using the Otsuka Long-Evans Tokushima Fatty rat model of type 2 diabetes and the Agilent rat microarray chip, we analyzed gene expression by comparing differential transcriptional changes in age-matched control versus diabetic hearts and diabetic hearts that received gene transfer of SERCA2a. Microarray expression profiles of selected genes were verified with real-time qPCR and immunoblotting. Our analysis indicates that diabetic cardiomyopathy is associated with a downregulation of transcripts. Diabetic cardiomyopathic hearts have reduced levels of SERCA2a. SERCA2a gene transfer in these hearts reduced diabetes-associated hypertrophy, and differentially modulated the expression of 76 genes and reversed the transcriptional profile induced by diabetes. In isolated cardiomyocytes in vitro, SERCA2a overexpression significantly modified the expression of a number of transcripts known to be involved in insulin signaling, glucose metabolism and cardiac remodeling. Conclusion This investigation provided insight into the pathophysiology of cardiac remodeling and the potential role of SERCA2a normalization in multiple pathways in diabetic cardiomyopathy.
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Affiliation(s)
- Ioannis Karakikes
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Maengjo Kim
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Lahouaria Hadri
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Susumu Sakata
- Department of Physiology II, Nara Medical University, Kashihara, Nara, Japan
| | - Yezhou Sun
- Bioinformatics Laboratory of Personalized Medicine Research Program, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Weijia Zhang
- Bioinformatics Laboratory of Personalized Medicine Research Program, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Elie R. Chemaly
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Roger J. Hajjar
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Djamel Lebeche
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
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Rubio M, Avitabile D, Fischer K, Emmanuel G, Gude N, Miyamoto S, Mishra S, Schaefer EM, Brown JH, Sussman MA. Cardioprotective stimuli mediate phosphoinositide 3-kinase and phosphoinositide dependent kinase 1 nuclear accumulation in cardiomyocytes. J Mol Cell Cardiol 2009; 47:96-103. [PMID: 19269295 DOI: 10.1016/j.yjmcc.2009.02.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 02/04/2009] [Accepted: 02/20/2009] [Indexed: 12/20/2022]
Abstract
The phosphoinositide 3-kinase (PI3K)/phosphoinositide dependent kinase 1 (PDK1) signaling pathway exerts cardioprotective effects in the myocardium through activation of key proteins including Akt. Activated Akt accumulates in nuclei of cardiomyocytes suggesting that biologically relevant targets are located in that subcellular compartment. Nuclear Akt activity could be potentiated in both intensity and duration by the presence of a nuclear-associated PI3K/PDK1 signaling cascade as has been described in other non-myocyte cell types. PI3K/PDK1 distribution was determined in vitro and in vivo by immunostaining and nuclear extraction of cultured rat neonatal cardiomyocytes or transgenic mouse hearts. Results show that PI3K and PDK1 are present at a basal level in cardiomyocytes nuclei and that cardioprotective stimulation with atrial natriuretic peptide (ANP) increases their nuclear localization. In comparison, overexpression of nuclear-targeted Akt does not mediate increased translocation of either PI3K or PDK1 indicating that accumulation of Akt does not drive PI3K or PDK1 into the nuclear compartment. Furthermore, PI3K and phospho-Akt(473) show parallel temporal accumulation in the nucleus following (MI) infarction challenge. These findings demonstrate the presence of a dynamically regulated nuclear-associated signaling cascade involving PI3K and PDK that presumably influences nuclear Akt activation.
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Affiliation(s)
- Marta Rubio
- SDSU Heart Institute, Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA.
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Yalcin A, Telang S, Clem B, Chesney J. Regulation of glucose metabolism by 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases in cancer. Exp Mol Pathol 2009; 86:174-9. [PMID: 19454274 DOI: 10.1016/j.yexmp.2009.01.003] [Citation(s) in RCA: 277] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A high rate of glycolytic flux, even in the presence of oxygen, is a central metabolic hallmark of neoplastic tumors. Cancer cells preferentially utilize glycolysis in order to satisfy their increased energetic and biosynthetic requirements. This metabolic phenotype has been confirmed in human studies using positron emission tomography (PET) with (18)F-2-fluoro-deoxy-glucose which have demonstrated that tumors take up 10-fold more glucose than adjacent normal tissues in vivo. The high glucose metabolism of cancer cells is caused by a combination of hypoxia-responsive transcription factors, activation of oncogenic proteins and the loss of tumor suppressor function. Over-expression of HIF-1alpha and myc, activation of ras and loss of p53 function each have been found to stimulate glycolysis in part by activating a family of regulatory bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB). The PFKFB enzymes synthesize fructose-2,6-bisphosphate (F2,6BP) which allosterically activates 6-phosphofructo-1-kinase (PFK-1), a rate-limiting enzyme and essential control point in the glycolytic pathway. PFK-1 is inhibited by ATP when energy stores are abundant and F2,6BP can override this inhibition and enhance glucose uptake and glycolytic flux. It is therefore not surprising that F2,6BP synthesis is stimulated by several oncogenic alterations which simultaneously cause both enhanced consumption of glucose and growth. Importantly, these studies suggest that selective depletion of intracellular F2,6BP in cancer cells may suppress glycolytic flux and decrease their survival, growth and invasiveness. This review will summarize the requirement of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases for the regulation of glycolysis in tumor cells and their potential utility as targets for the development of antineoplastic agents.
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Affiliation(s)
- Abdullah Yalcin
- Department of Medicine, Medical Oncology, James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
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Wang Q, Donthi RV, Wang J, Lange AJ, Watson LJ, Jones SP, Epstein PN. Cardiac phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase increases glycolysis, hypertrophy, and myocyte resistance to hypoxia. Am J Physiol Heart Circ Physiol 2008; 294:H2889-97. [PMID: 18456722 DOI: 10.1152/ajpheart.91501.2007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During ischemia and heart failure, there is an increase in cardiac glycolysis. To understand if this is beneficial or detrimental to the heart, we chronically elevated glycolysis by cardiac-specific overexpression of phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) in transgenic mice. PFK-2 controls the level of fructose-2,6-bisphosphate (Fru-2,6-P2), an important regulator of phosphofructokinase and glycolysis. Transgenic mice had over a threefold elevation in levels of Fru-2,6-P2. Cardiac metabolites upstream of phosphofructokinase were significantly reduced, as would be expected by the activation of phosphofructokinase. In perfused hearts, the transgene caused a significant increase in glycolysis that was less sensitive to inhibition by palmitate. Conversely, oxidation of palmitate was reduced by close to 50%. The elevation in glycolysis made isolated cardiomyocytes highly resistant to contractile inhibition by hypoxia, but in vivo the transgene had no effect on ischemia-reperfusion injury. Transgenic hearts exhibited pathology: the heart weight-to-body weight ratio was increased 17%, cardiomyocyte length was greater, and cardiac fibrosis was increased. However, the transgene did not change insulin sensitivity. These results show that the elevation in glycolysis provides acute benefits against hypoxia, but the chronic increase in glycolysis or reduction in fatty acid oxidation interferes with normal cardiac metabolism, which may be detrimental to the heart.
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Affiliation(s)
- Qianwen Wang
- Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky, USA
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A role for PFK-2/FBPase-2, as distinct from fructose 2,6-bisphosphate, in regulation of insulin secretion in pancreatic β-cells. Biochem J 2008; 411:41-51. [DOI: 10.1042/bj20070962] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PFK-2/FBPase-2 (6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase) catalyses the formation and degradation of fructose 2,6-P2 (fructose 2,6-bisphosphate) and is also a glucokinase-binding protein. The role of fructose 2,6-P2 in regulating glucose metabolism and insulin secretion in pancreatic β-cells is unresolved. We down-regulated the endogenous isoforms of PFK-2/FBPase-2 with siRNA (small interfering RNA) and expressed KA (kinase active) and KD (kinase deficient) variants to distinguish between the role of PFK-2/FBPase-2 protein and the role of its product, fructose 2,6-P2, in regulating β-cell function. Human islets expressed the PFKFB2 (the gene encoding isoform 2 of the PFK2/FBPase2 protein) and PFKFB3 (the gene encoding isoform 3 of the PFK2/FBPase2 protein) isoforms and mouse islets expressed PFKFB2 at the mRNA level [RT–PCR (reverse transcription–PCR)]. Rat islets expressed PFKFB2 lacking the C-terminal phosphorylation sites. The glucose-responsive MIN6 and INS1E cell lines expressed PFKFB2 and PFKFB3. PFK-2 activity and the cell content of fructose 2,6-P2 were increased by elevated glucose concentration and during pharmacological activation of AMPK (AMP-activated protein kinase), which also increased insulin secretion. Partial down-regulation of endogenous PFKFB2 and PFKFB3 in INS1E by siRNA decreased PFK-2/FBPase-2 protein, fructose 2,6-P2 content, glucokinase activity and glucoseinduced insulin secretion. Selective down-regulation of glucose-induced fructose 2,6-P2 in the absence of down-regulation of PFK-2/FBPase-2 protein, using a KD PFK-2/FBPase-2 variant, resulted in sustained glycolysis and elevated glucose-induced insulin secretion, indicating an over-riding role of PFK-2/FBPase-2 protein, as distinct from its product fructose 2,6-P2, in potentiating glucose-induced insulin secretion. Whereas down-regulation of PFK-2/FBPase-2 decreased glucokinase activity, overexpression of PFK-2/FBPase-2 only affected glucokinase distribution. It is concluded that PFK-2/FBPase-2 protein rather than its product fructose 2,6-P2 is the over-riding determinant of glucose-induced insulin secretion through regulation of glucokinase activity or subcellular targeting.
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Affiliation(s)
- Lawrence H. Young
- From the Departments of Internal Medicine (Section of Cardiovascular Medicine) and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Conn
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Feuvray D, Darmellah A. Diabetes-related metabolic perturbations in cardiac myocyte. DIABETES & METABOLISM 2008; 34 Suppl 1:S3-9. [DOI: 10.1016/s1262-3636(08)70096-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 10/30/2007] [Indexed: 12/21/2022]
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Screening of AMP-activated protein kinase alpha2 subunit interacting proteins by bacterial two-hybrid system. Mol Biol Rep 2007; 36:337-44. [PMID: 18034317 DOI: 10.1007/s11033-007-9184-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Accepted: 11/12/2007] [Indexed: 12/14/2022]
Abstract
AMP-activated protein kinase (AMPK) is a ubiquitous eukaryotic protein kinase regulating cellular metabolism and energy demand. In brain AMPK plays a role as a multidimensional energy sensor and AMPK alpha2 subunit is expressed at higher levels than AMPK alpha1 subunit. In order to identify potential targets of AMPK in brain, we perform bacterial two-hybrid screening of a rat fetal brain cDNA library using AMPK alpha2 subunit as bait. Here, we present seven potential AMPK alpha2 subunit interacting proteins, including 6-phosphofructo-1-kinase (PFK-1), polyubiquitin, cytochrome c oxidase subunit I (COX I), heat shock protein 8 (HSP8), HLA-B-associated transcript 3 (BAT3) isoform 1, protein tyrosine phosphatase receptor type D (PTPRD) and islet-brain 1 (IB1). They are involved in glycolysis, protein degradation, mitochondrial electron transport and apoptosis pathways participating in energy regulation directly or indirectly. These data may provide new insight into further studying the pathways of AMPK energy regulation in brain and possible mechanisms of AMPK-mediated neuroprotective effect.
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Huang J, Gabrielsen JS, Cooksey RC, Luo B, Boros LG, Jones DL, Jouihan HA, Soesanto Y, Knecht L, Hazel MW, Kushner JP, McClain DA. Increased glucose disposal and AMP-dependent kinase signaling in a mouse model of hemochromatosis. J Biol Chem 2007; 282:37501-7. [PMID: 17971451 DOI: 10.1074/jbc.m703625200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Hereditary hemochromatosis is an inherited disorder of increased iron absorption that can result in cirrhosis, diabetes, and other morbidities. We have investigated the mechanisms underlying supranormal glucose tolerance despite decreased insulin secretion in a mouse model of hemochromatosis with deletion of the hemochromatosis gene (Hfe(-/-)). Hfe(-/-) mice on 129Sv or C57BL/6J backgrounds have decreased glucose excursions after challenge compared with controls. In the C57BL/6J/ Hfe(-/-), for example, incremental area under the glucose curve is reduced 52% (p < 0.001) despite decreased serum insulin, and homeostasis model assessment insulin resistance is decreased 50% (p < 0.05). When studied by the euglycemic clamp technique 129Sv/Hfe(-/-) mice exhibit a 20% increase in glucose disposal (p < 0.05) at submaximal insulin but no increase at maximal insulin compared with wild types. [1,2-(13)C]D-glucose clearance from plasma is significantly increased in Hfe(-/-) mice (19%, p < 0.05), and lactate derived from glycolysis is elevated 5.1-fold in Hfe(-/-) mice (p < 0.0001). Basal but not insulin-stimulated glucose uptake is elevated in isolated soleus muscle from Hfe(-/-) mice (p < 0.03). Compared with controls Hfe(-/-) mice exhibit no differences in serum lipid, insulin, glucagon, or thyroid hormone levels; adiponectin levels are elevated 41% (p < 0.05), and the adiponectin message in adipocytes is increased 83% (p = 0.04). Insulin action measured by phosphorylation of Akt is not enhanced in muscle, but phosphorylation of AMP-dependent kinase is increased. We conclude that supranormal glucose tolerance in iron overload is characterized by increased glucose disposal that does not result from increased insulin action. Instead, the Hfe(-/-) mice demonstrate increased adiponectin levels and activation of AMP-dependent kinase.
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Affiliation(s)
- Jingyu Huang
- Department of Biochemistry, the University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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Shaw MM, Gurr WK, McCrimmon RJ, Schorderet DF, Sherwin RS. 5'AMP-activated protein kinase alpha deficiency enhances stress-induced apoptosis in BHK and PC12 cells. J Cell Mol Med 2007; 11:286-98. [PMID: 17488477 PMCID: PMC3822827 DOI: 10.1111/j.1582-4934.2007.00023.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
5'AMP-activated protein kinase (AMPK) activation occurs under a variety of stress conditions but the role of this enzyme in the promotion or inhibition of stress-induced cell death is unclear. To address this issue, we transformed two different cell lines with shRNA-expressing plasmids, targeting the alpha subunit of AMPK, and verified AMPKalpha downregulation. The cell lines were then stressed by exposure to medium without glucose (PC12 cells) or with the viral thymidine kinase-specific DNA replication inhibitors: acyclovir, penciclovir and ganciclovir (herpes simplex virus thymidine kinase-expressing Baby Hamster Kidney cells). In non-AMPK-downregulated cells, these stress treatments induced AMPK upregulation and phosphorylation, leaving open the question whether the association of AMPK activation with stress-induced cell death reflects a successful death-promoting or an ineffective death-inhibiting activity. In AMPKalpha-deficient cells (expressing AMPKalpha-specific shRNAs or treated with Compound C) exposure to low glucose medium or DNA replication inhibitors led to an enhancement of cell death, indicating that, under the conditions examined, the role of activated AMPK is not to promote, but to protect from or delay stress-induced cell death.
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Affiliation(s)
- Margaret M Shaw
- Institut de Recherche en Ophtalmologie, Avenue de Grand-Champsec 64, 1950 Sion, Switzerland.
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Abstract
H11 kinase (H11K) is a small heat shock protein expressed predominantly in the heart and skeletal muscle, which plays a critical role in the maintenance of cardiac cell survival and in promoting cell growth through the activation of complementary signaling pathways. An overexpression of H11K was detected in various forms of heart disease, both in animal models and in patients, including acute and chronic ventricular dysfunction, and myocardial hypertrophy. Overexpression of H11K was reproduced in a cardiac-specific transgenic model, which led to significant progress in understanding the role and mechanism of action of the protein. Increased expression of H11K confers a cardioprotection that is equivalent to ischemic preconditioning; it promotes cardiac hypertrophy while maintaining contractile function. The overexpression of H11K is sufficient to activate most of the signaling pathways involved in cardiac cell growth and survival, including the phosphatidylinositol-3-kinase/Akt pathway, the AMP-dependent protein kinase, the PKCepsilon pathway of ischemic preconditioning, the nitric oxide pathway of delayed cardioprotection, and the mTOR pathway of cell growth. As a result, the survival response triggered by H11K in the heart includes antiapoptosis, cytoprotection, preconditioning, growth, and metabolic stimulation. In addition to activating signaling pathways, H11K promotes the subcellular translocation and crosstalk of intracellular messengers. This review discusses the biological function of H11K, its molecular mechanisms of action, and its potential therapeutic relevance. In particular, we discuss how preemptive conditioning of the heart by H11K might be beneficial for patients with ischemic heart disease who would be at risk of further irreversible cardiac damage.
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Affiliation(s)
- Ilan J Danan
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA
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Ouwens DM, Diamant M. Myocardial insulin action and the contribution of insulin resistance to the pathogenesis of diabetic cardiomyopathy. Arch Physiol Biochem 2007; 113:76-86. [PMID: 17558606 DOI: 10.1080/13813450701422633] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heart disease is the leading cause of death in patients with insulin resistance and type 2 diabetes (DM2). Even in the absence of coronary artery disease and hypertension, functional and structural abnormalities exist in patients with well-controlled and uncomplicated DM2. These derangements are collectively designated by the term diabetic cardiomyopathy (DCM). Changes in myocardial energy metabolism, due to altered substrate supply and utilization, largely underlie the development of DCM. Insulin is an important regulator of myocardial substrate metabolism, but also exerts regulatory effects on intracellular Ca2+ handling and cell survival. The current paper reviews the multiple functional and molecular effects of insulin on the heart, all of which ultimately seem to be cardioprotective both under normal conditions and under ischemia. In particular, the dismal consequences of myocardial insulin resistance contributing to the development of DCM will be discussed.
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Affiliation(s)
- D M Ouwens
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands.
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Wu Y, Wang H, Brautigan DL, Liu Z. Activation of glycogen synthase in myocardium induced by intermittent hypoxia is much lower in fasted than in fed rats. Am J Physiol Endocrinol Metab 2007; 292:E469-75. [PMID: 17003235 DOI: 10.1152/ajpendo.00486.2006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Obstructive sleep apnea is characterized by intermittent obstruction of the upper airway, which leads to intermittent hypoxia. Myocardial glycogen is a major energy resource for heart during hypoxia. Previous studies have demonstrated that intermittent hypoxia rapidly degrades myocardial glycogen and activates glycogen synthase (GS). However, the underlying mechanisms remain undefined. Because sleep apnea/intermittent hypoxia usually happens at night, whether intermittent hypoxia leads to GS activation in the postabsorptive state is not known. In the present study, male adult rats were studied after either an overnight fast or ad libitum feeding with or without intermittent ventilatory arrest (3 90-s periods at 10-min intervals). Hearts were quickly excised and freeze-clamped. Intermittent hypoxia induced a significant decrease in myocardial glycogen content in fed rats and stimulated GS in both fasted and fed rats. However, the portion of GS in the active form increased by approximately 38% in fasted rats compared with a larger, approximately 130% increase in fed rats. The basal G-6-P content was comparable in fasted and fed animals and increased approximately threefold after hypoxia. The basal phosphorylation states of Akt and GSK-3beta and the activity of protein phosphatase 1 (PP1) were comparable between fasted and fed control rats. Hypoxia significantly increased Akt phosphorylation and PP1 activity only in fed rats. In contrast, hypoxia did not induce significant change in GSK-3beta phosphorylation in either fasted or fed rats. We conclude that hypoxia activates GS in fed rat myocardium through a combination of rapid glycogenolysis, elevated local G-6-P content, and increased PP1 activity, and fasting attenuates this action independent of local G-6-P content.
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Affiliation(s)
- Yangsong Wu
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Virginia Health System, P. O. Box 801410, Charlottesville, VA 22908-1410, USA
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