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Smiles WJ, Ovens AJ, Oakhill JS, Kofler B. The metabolic sensor AMPK: Twelve enzymes in one. Mol Metab 2024; 90:102042. [PMID: 39362600 DOI: 10.1016/j.molmet.2024.102042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2024] [Revised: 09/12/2024] [Accepted: 09/27/2024] [Indexed: 10/05/2024] Open
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) is an evolutionarily conserved regulator of energy metabolism. AMPK is sensitive to acute perturbations to cellular energy status and leverages fundamental bioenergetic pathways to maintain cellular homeostasis. AMPK is a heterotrimer comprised of αβγ-subunits that in humans are encoded by seven individual genes (isoforms α1, α2, β1, β2, γ1, γ2 and γ3), permitting formation of at least 12 different complexes with personalised biochemical fingerprints and tissue expression patterns. While the canonical activation mechanisms of AMPK are well-defined, delineation of subtle, as well as substantial, differences in the regulation of heterogenous AMPK complexes remain poorly defined. SCOPE OF REVIEW Here, taking advantage of multidisciplinary findings, we dissect the many aspects of isoform-specific AMPK function and links to health and disease. These include, but are not limited to, allosteric activation by adenine nucleotides and small molecules, co-translational myristoylation and post-translational modifications (particularly phosphorylation), governance of subcellular localisation, and control of transcriptional networks. Finally, we delve into current debate over whether AMPK can form novel protein complexes (e.g., dimers lacking the α-subunit), altogether highlighting opportunities for future and impactful research. MAJOR CONCLUSIONS Baseline activity of α1-AMPK is higher than its α2 counterpart and is more sensitive to synergistic allosteric activation by metabolites and small molecules. α2 complexes however, show a greater response to energy stress (i.e., AMP production) and appear to be better substrates for LKB1 and mTORC1 upstream. These differences may explain to some extent why in certain cancers α1 is a tumour promoter and α2 a suppressor. β1-AMPK activity is toggled by a 'myristoyl-switch' mechanism that likely precedes a series of signalling events culminating in phosphorylation by ULK1 and sensitisation to small molecules or endogenous ligands like fatty acids. β2-AMPK, not entirely beholden to this myristoyl-switch, has a greater propensity to infiltrate the nucleus, which we suspect contributes to its oncogenicity in some cancers. Last, the unique N-terminal extensions of the γ2 and γ3 isoforms are major regulatory domains of AMPK. mTORC1 may directly phosphorylate this region in γ2, although whether this is inhibitory, especially in disease states, is unclear. Conversely, γ3 complexes might be preferentially regulated by mTORC1 in response to physical exercise.
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Affiliation(s)
- William J Smiles
- Research Program for Receptor Biochemistry and Tumour Metabolism, Department of Paediatrics, University Hospital of the Paracelsus Medical University, Salzburg, Austria; Metabolic Signalling Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Melbourne, Australia.
| | - Ashley J Ovens
- Protein Engineering in Immunity & Metabolism, St. Vincent's Institute of Medical Research, Fitzroy, Melbourne, Australia
| | - Jonathan S Oakhill
- Metabolic Signalling Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Melbourne, Australia; Department of Medicine, University of Melbourne, Parkville, Australia
| | - Barbara Kofler
- Research Program for Receptor Biochemistry and Tumour Metabolism, Department of Paediatrics, University Hospital of the Paracelsus Medical University, Salzburg, Austria
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Tang M, Su Q, Duan Y, Fu Y, Liang M, Pan Y, Yuan J, Wang M, Pang X, Ma J, Laher I, Li S. The role of MOTS-c-mediated antioxidant defense in aerobic exercise alleviating diabetic myocardial injury. Sci Rep 2023; 13:19781. [PMID: 37957221 PMCID: PMC10643467 DOI: 10.1038/s41598-023-47073-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 11/08/2023] [Indexed: 11/15/2023] Open
Abstract
Myocardial remodeling and dysfunction are commonly observed in type 2 diabetes mellitus (T2DM). Aerobic exercise can partly alleviate diabetes-induced myocardial dysfunction through its antioxidant actions. MOTS-c is a potential exercise mimic. This study aimed to investigate the effects of MOTS-c on improving diabetic heart function and its mechanism and to identify whether MOTS-c improved antioxidant defenses due to aerobic exercise. Herein, we established a rat model of T2DM induced by high-fat diet combined with a low-dose streptozotocin injection. Interventions were performed using intraperitoneal injections of MOTS-c (i.p. 0.5 mg/kg/day, 7 days/week) or aerobic exercise training (treadmill, 20 m/min, 60 min/day, 5 days/week) for 8 weeks. Myocardial ultrastructure was assessed using transmission electron microscopy (TEM), myocardial lipid peroxidation levels (MDA), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) levels were assessed using colorimetric methods, and molecular analyses including MOTS-c, Kelch-like ECH-associated protein 1 (Keap1), Nuclear factor E2-related factor 2 (Nrf2), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)and phospho-AMPK (p-AMPK) were examined using Western blot. The results showed that MOTS-c, with or without exercise, reduced myocardial ultrastructural damage and improved glucolipid metabolism and cardiac function in T2DM. Furthermore, MOTS-c increased antioxidant markers such as SOD, CAT, and the protein expression of myocardial MOTS-c, Keap1, Nrf2, and p-AMPK. MOTS-c with exercise treatment reduced myocardial MDA and increased p-AMPK significantly comparing to only exercise or MOTS-c alone. Our findings suggest that MOTS-c may be a helpful supplement for overcoming exercise insufficiency and improving myocardial structure and function in diabetes.
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Affiliation(s)
- Mi Tang
- School of Physical Education, Xihua University, Chengdu, 610039, China
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Quansheng Su
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Yimei Duan
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Yu Fu
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Min Liang
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Yanrong Pan
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Jinghan Yuan
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Manda Wang
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Xiaoli Pang
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Jiacheng Ma
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China
| | - Ismail Laher
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - Shunchang Li
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, 610041, China.
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Nichenko AS, Specht KS, Craige SM, Drake JC. Sensing local energetics to acutely regulate mitophagy in skeletal muscle. Front Cell Dev Biol 2022; 10:987317. [PMID: 36105350 PMCID: PMC9465048 DOI: 10.3389/fcell.2022.987317] [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: 07/06/2022] [Accepted: 08/01/2022] [Indexed: 01/04/2023] Open
Abstract
The energetic requirements of skeletal muscle to sustain movement, as during exercise, is met largely by mitochondria, which form an intricate, interconnected reticulum. Maintenance of a healthy mitochondrial reticulum is essential for skeletal muscle function, suggesting quality control pathways are spatially governed. Mitophagy, the process by which damaged and/or dysfunctional regions of the mitochondrial reticulum are removed and degraded, has emerged as an integral part of the molecular response to exercise. Upregulation of mitophagy in response to acute exercise is directly connected to energetic sensing mechanisms through AMPK. In this review, we discuss the connection of mitophagy to muscle energetics and how AMPK may spatially control mitophagy through multiple potential means.
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Rothschild JA, Islam H, Bishop DJ, Kilding AE, Stewart T, Plews DJ. Factors Influencing AMPK Activation During Cycling Exercise: A Pooled Analysis and Meta-Regression. Sports Med 2021; 52:1273-1294. [PMID: 34878641 DOI: 10.1007/s40279-021-01610-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2021] [Indexed: 01/14/2023]
Abstract
BACKGROUND The 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a cellular energy sensor that is activated by increases in the cellular AMP/adenosine diphosphate:adenosine triphosphate (ADP:ATP) ratios and plays a key role in metabolic adaptations to endurance training. The degree of AMPK activation during exercise can be influenced by many factors that impact on cellular energetics, including exercise intensity, exercise duration, muscle glycogen, fitness level, and nutrient availability. However, the relative importance of these factors for inducing AMPK activation remains unclear, and robust relationships between exercise-related variables and indices of AMPK activation have not been established. OBJECTIVES The purpose of this analysis was to (1) investigate correlations between factors influencing AMPK activation and the magnitude of change in AMPK activity during cycling exercise, (2) investigate correlations between commonly reported measures of AMPK activation (AMPK-α2 activity, phosphorylated (p)-AMPK, and p-acetyl coenzyme A carboxylase (p-ACC), and (3) formulate linear regression models to determine the most important factors for AMPK activation during exercise. METHODS Data were pooled from 89 studies, including 982 participants (93.8% male, maximal oxygen consumption [[Formula: see text]] 51.9 ± 7.8 mL kg-1 min-1). Pearson's correlation analysis was performed to determine relationships between effect sizes for each of the primary outcome markers (AMPK-α2 activity, p-AMPK, p-ACC) and factors purported to influence AMPK signaling (muscle glycogen, carbohydrate ingestion, exercise duration and intensity, fitness level, and muscle metabolites). General linear mixed-effect models were used to examine which factors influenced AMPK activation. RESULTS Significant correlations (r = 0.19-0.55, p < .05) with AMPK activity were found between end-exercise muscle glycogen, exercise intensity, and muscle metabolites phosphocreatine, creatine, and free ADP. All markers of AMPK activation were significantly correlated, with the strongest relationship between AMPK-α2 activity and p-AMPK (r = 0.56, p < 0.001). The most important predictors of AMPK activation were the muscle metabolites and exercise intensity. CONCLUSION Muscle glycogen, fitness level, exercise intensity, and exercise duration each influence AMPK activity during exercise when all other factors are held constant. However, disrupting cellular energy charge is the most influential factor for AMPK activation during endurance exercise.
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Affiliation(s)
- Jeffrey A Rothschild
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand.
| | - Hashim Islam
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - David J Bishop
- Institute for Health and Sport (iHeS), Victoria University, Melbourne, VIC, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Andrew E Kilding
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Tom Stewart
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Daniel J Plews
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
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Mitochondria-localized AMPK responds to local energetics and contributes to exercise and energetic stress-induced mitophagy. Proc Natl Acad Sci U S A 2021; 118:2025932118. [PMID: 34493662 PMCID: PMC8449344 DOI: 10.1073/pnas.2025932118] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 08/05/2021] [Indexed: 12/25/2022] Open
Abstract
Mitochondria form a complex, interconnected reticulum that is maintained through coordination among biogenesis, dynamic fission, and fusion and mitophagy, which are initiated in response to various cues to maintain energetic homeostasis. These cellular events, which make up mitochondrial quality control, act with remarkable spatial precision, but what governs such spatial specificity is poorly understood. Herein, we demonstrate that specific isoforms of the cellular bioenergetic sensor, 5' AMP-activated protein kinase (AMPKα1/α2/β2/γ1), are localized on the outer mitochondrial membrane, referred to as mitoAMPK, in various tissues in mice and humans. Activation of mitoAMPK varies across the reticulum in response to energetic stress, and inhibition of mitoAMPK activity attenuates exercise-induced mitophagy in skeletal muscle in vivo. Discovery of a mitochondrial pool of AMPK and its local importance for mitochondrial quality control underscores the complexity of sensing cellular energetics in vivo that has implications for targeting mitochondrial energetics for disease treatment.
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Ibeas K, Herrero L, Mera P, Serra D. Hypothalamus-skeletal muscle crosstalk during exercise and its role in metabolism modulation. Biochem Pharmacol 2021; 190:114640. [PMID: 34087244 DOI: 10.1016/j.bcp.2021.114640] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 11/15/2022]
Abstract
Physical inactivity is a major public health problem that contributes to the development of several pathologies such as obesity, type 2 diabetes and cardiovascular diseases. Regular exercise mitigates the progression of these metabolic problems and contributes positively to memory and behavior. Therefore, public health agencies have incorporated exercise in the treatment of widespread disorders. The hypothalamus, specifically the ventromedial and the arcuate nuclei, responds to exercise activity and modulates energy metabolism through stimulation of the sympathetic nervous system and catecholamine secretion into the circulation. In addition, physical performance enhances cognitive functions and memory, mediated mostly by an increase in brain-derived neurotrophic factor levels in brain. During exercise training, skeletal muscle myofibers remodel their biochemical, morphological and physiological state. Moreover, skeletal muscle interacts with other organs by the release into the circulation of myokines, molecules that exhibit autocrine, paracrine and endocrine functions. Several studies have focused on the role of skeletal muscle and tissues in response to physical activity. However, how the hypothalamus could influence the skeletal muscle task in the context of exercise is less studied. Here, we review recent data about hypothalamus-skeletal muscle crosstalk in response to physical activity and focus on specific aspects such as the neuroendocrinological effects of exercise and the endocrine functions of skeletal muscle, to provide a perspective for future study directions.
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Affiliation(s)
- Kevin Ibeas
- Regulation of Lipid Metabolism in Obesity and Diabetes, Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, E-08028 Barcelona, Spain
| | - Laura Herrero
- Regulation of Lipid Metabolism in Obesity and Diabetes, Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, E-08028 Barcelona, Spain; Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, E-28029 Madrid, Spain
| | - Paula Mera
- Regulation of Lipid Metabolism in Obesity and Diabetes, Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, E-08028 Barcelona, Spain
| | - Dolors Serra
- Regulation of Lipid Metabolism in Obesity and Diabetes, Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, E-08028 Barcelona, Spain; Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, E-28029 Madrid, Spain.
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7
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Edinburgh RM, Koumanov F, Gonzalez JT. Impact of pre‐exercise feeding status on metabolic adaptations to endurance‐type exercise training. J Physiol 2021; 600:1327-1338. [DOI: 10.1113/jp280748] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/29/2020] [Indexed: 12/16/2022] Open
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8
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Jevtovic F. Combination of Metformin and Exercise in Management of Metabolic Abnormalities Observed in Type 2 Diabetes Mellitus. Diabetes Metab Syndr Obes 2021; 14:4043-4057. [PMID: 34557007 PMCID: PMC8453852 DOI: 10.2147/dmso.s328694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/07/2021] [Indexed: 12/19/2022] Open
Abstract
Excess nutrient intake and lack of exercise characterize the problem of obesity and are common factors in insulin resistance (IR). With an increasing number of prediabetic, and type 2 diabetic populations, metformin is still the most prescribed glucose-lowering drug and is often accompanied by recommendations for regular physical exercise. Metformin, by the inhibition of complex 1 of the electron transport chain, and exercise, by increasing energy expenditure, both elicit a low cellular energy state that leads to improvements in glucose control via activation of adenosine 5' monophosphate-activated protein kinase (AMPK). An augmented stimulation of the energy-sensing enzyme AMPK by either of the two modalities leads to an increase in glycogenolysis, glucose uptake, fat oxidation, a decrease in glycogen and protein synthesis, and gluconeogenesis in muscle and the liver, which are remarked as having positive effects on metabolic pathophysiology observed in IR and type 2 diabetes mellitus (T2DM). While both modalities exploit the energy-sensing enzyme AMPK to attain glucose homeostasis, the synergistic effect of these two treatments is not distinctly supported by the literature. Further, an antagonistic dynamic has been observed in cases where metformin and exercise were combined. Reduction of insulin-sensitizing effects of exercise and an overall hindrance of exercise performance and adaptations have been reported and could suggest the possible incongruity of these two modalities. The aim of this review is to elucidate the effect that metformin and exercise have on the management of the metabolic abnormalities observed in T2DM and to provide an insight into the interaction of these two modalities.
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Affiliation(s)
- Filip Jevtovic
- Department of Kinesiology, College of Health and Human Performance, East Carolina University, Greenville, NC, USA
- Correspondence: Filip Jevtovic East Carolina University; School of Dental Medicine, Ledyard E. Ross Hall; 1851 MacGregor Downs Road, Mail Stop 701, Greenville, NC, 27834, USATel +1 616 844 8323Fax +1 252 737 7024 Email
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Hansen SL, Bojsen-Møller KN, Lundsgaard AM, Hendrich FL, Nilas L, Sjøberg KA, Hingst JR, Serup AK, Olguín CH, Carl CS, Wernblad LF, Henneberg M, Lustrup KM, Hansen C, Jensen TE, Madsbad S, Wojtaszewski JFP, Richter EA, Kiens B. Mechanisms Underlying Absent Training-Induced Improvement in Insulin Action in Lean, Hyperandrogenic Women With Polycystic Ovary Syndrome. Diabetes 2020; 69:2267-2280. [PMID: 32873590 DOI: 10.2337/db20-0062] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 08/24/2020] [Indexed: 11/13/2022]
Abstract
Women with polycystic ovary syndrome (PCOS) have been shown to be less insulin sensitive compared with control (CON) women, independent of BMI. Training is associated with molecular adaptations in skeletal muscle, improving glucose uptake and metabolism in both healthy individuals and patients with type 2 diabetes. In the current study, lean hyperandrogenic women with PCOS (n = 9) and healthy CON women (n = 9) completed 14 weeks of controlled and supervised exercise training. In CON, the training intervention increased whole-body insulin action by 26% and insulin-stimulated leg glucose uptake by 53% together with increased insulin-stimulated leg blood flow and a more oxidative muscle fiber type distribution. In PCOS, no such changes were found, despite similar training intensity and improvements in VO2max In skeletal muscle of CON but not PCOS, training increased GLUT4 and HKII mRNA and protein expressions. These data suggest that the impaired increase in whole-body insulin action in women with PCOS with training is caused by an impaired ability to upregulate key glucose-handling proteins for insulin-stimulated glucose uptake in skeletal muscle and insulin-stimulated leg blood flow. Still, other important benefits of exercise training appeared in women with PCOS, including an improvement of the hyperandrogenic state.
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Affiliation(s)
- Solvejg L Hansen
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Anne-Marie Lundsgaard
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Frederikke L Hendrich
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Lisbeth Nilas
- Department of Obstetrics and Gynaecology, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Kim A Sjøberg
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Janne R Hingst
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Annette K Serup
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Carlos Henríquez Olguín
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Christian S Carl
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Louise F Wernblad
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Marie Henneberg
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Katja M Lustrup
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Christine Hansen
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E Jensen
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Sten Madsbad
- Department of Endocrinology, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Jørgen F P Wojtaszewski
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Erik A Richter
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Molecular Physiology Section, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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10
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Edinburgh RM, Bradley HE, Abdullah NF, Robinson SL, Chrzanowski-Smith OJ, Walhin JP, Joanisse S, Manolopoulos KN, Philp A, Hengist A, Chabowski A, Brodsky FM, Koumanov F, Betts JA, Thompson D, Wallis GA, Gonzalez JT. Lipid Metabolism Links Nutrient-Exercise Timing to Insulin Sensitivity in Men Classified as Overweight or Obese. J Clin Endocrinol Metab 2020; 105:dgz104. [PMID: 31628477 PMCID: PMC7112968 DOI: 10.1210/clinem/dgz104] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/02/2019] [Indexed: 02/06/2023]
Abstract
CONTEXT Pre-exercise nutrient availability alters acute metabolic responses to exercise, which could modulate training responsiveness. OBJECTIVE To assess acute and chronic effects of exercise performed before versus after nutrient ingestion on whole-body and intramuscular lipid utilization and postprandial glucose metabolism. DESIGN (1) Acute, randomized, crossover design (Acute Study); (2) 6-week, randomized, controlled design (Training Study). SETTING General community. PARTICIPANTS Men with overweight/obesity (mean ± standard deviation, body mass index: 30.2 ± 3.5 kg⋅m-2 for Acute Study, 30.9 ± 4.5 kg⋅m-2 for Training Study). INTERVENTIONS Moderate-intensity cycling performed before versus after mixed-macronutrient breakfast (Acute Study) or carbohydrate (Training Study) ingestion. RESULTS Acute Study-exercise before versus after breakfast consumption increased net intramuscular lipid utilization in type I (net change: -3.44 ± 2.63% versus 1.44 ± 4.18% area lipid staining, P < 0.01) and type II fibers (-1.89 ± 2.48% versus 1.83 ± 1.92% area lipid staining, P < 0.05). Training Study-postprandial glycemia was not differentially affected by 6 weeks of exercise training performed before versus after carbohydrate intake (P > 0.05). However, postprandial insulinemia was reduced with exercise training performed before but not after carbohydrate ingestion (P = 0.03). This resulted in increased oral glucose insulin sensitivity (25 ± 38 vs -21 ± 32 mL⋅min-1⋅m-2; P = 0.01), associated with increased lipid utilization during exercise (r = 0.50, P = 0.02). Regular exercise before nutrient provision also augmented remodeling of skeletal muscle phospholipids and protein content of the glucose transport protein GLUT4 (P < 0.05). CONCLUSIONS Experiments investigating exercise training and metabolic health should consider nutrient-exercise timing, and exercise performed before versus after nutrient intake (ie, in the fasted state) may exert beneficial effects on lipid utilization and reduce postprandial insulinemia.
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Affiliation(s)
| | - Helen E Bradley
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Nurul-Fadhilah Abdullah
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- Department of Health Sciences, Faculty of Sport Sciences and Coaching, Universiti Pendidikan Sultan Idris, Perak, Malaysia
| | - Scott L Robinson
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | | | | | - Sophie Joanisse
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | | | - Andrew Philp
- Diabetes & Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Aaron Hengist
- Department for Health, University of Bath, Bath, United Kingdom
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Frances M Brodsky
- Division of Biosciences, University College London, London, United Kingdom
| | | | - James A Betts
- Department for Health, University of Bath, Bath, United Kingdom
| | - Dylan Thompson
- Department for Health, University of Bath, Bath, United Kingdom
| | - Gareth A Wallis
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
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Møller AB, Lønbro S, Farup J, Voss TS, Rittig N, Wang J, Højris I, Mikkelsen UR, Jessen N. Molecular and cellular adaptations to exercise training in skeletal muscle from cancer patients treated with chemotherapy. J Cancer Res Clin Oncol 2019; 145:1449-1460. [PMID: 30968255 DOI: 10.1007/s00432-019-02911-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 03/28/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND A growing body of evidence suggests that exercise training has beneficial effects in cancer patients. The aim of the present study was to investigate the molecular basis underlying these beneficial effects in skeletal muscle from cancer patients. METHODS We investigated expression of selected proteins involved in cellular processes known to orchestrate adaptation to exercise training by western blot. Skeletal muscle biopsies were sampled from ten cancer patients before and after 4-7 weeks of ongoing chemotherapy, and subsequently after 10 weeks of continued chemotherapy in combination with exercise training. Biopsies from ten healthy matched subjects served as reference. RESULTS The expression of the insulin-regulated glucose transporter, GLUT4, increased during chemotherapy and continued to increase during exercise training. A similar trend was observed for ACC, a key enzyme in the biosynthesis and oxidation of fatty acids, but we did not observe any changes in other regulators of substrate metabolism (AMPK and PDH) or mitochondrial proteins (Cyt-C, COX-IV, SDHA, and VDAC). Markers of proteasomal proteolysis (MURF1 and ATROGIN-1) decreased during chemotherapy, but did not change further during chemotherapy combined with exercise training. A similar pattern was observed for autophagy-related proteins such as ATG5, p62, and pULK1 Ser757, but not ULK1 and LC3BII/LC3BI. Phosphorylation of FOXO3a at Ser318/321 did not change during chemotherapy, but decreased during exercise training. This could suggest that FOXO3a-mediated transcriptional regulation of MURF1 and ATROGIN-1 serves as a mechanism by which exercise training maintains proteolytic systems in skeletal muscle in cancer patients. Phosphorylation of proteins that regulate protein synthesis (mTOR at Ser2448 and 4EBP1 at Thr37/46) increased during chemotherapy and leveled off during exercise training. Finally, chemotherapy tended to increase the number of satellite cells in type 1 fibers, without any further change during chemotherapy and exercise training. Conversely, the number of satellite cells in type 2 fibers did not change during chemotherapy, but increased during chemotherapy combined with exercise training. CONCLUSIONS Molecular signaling cascades involved in exercise training are disturbed during cancer and chemotherapy, and exercise training may prevent further disruption of these pathways. TRIAL REGISTRATION The study was approved by the local Scientific Ethics Committee of the Central Denmark Region (Project ID: M-2014-15-14; date of approval: 01/27/2014) and the Danish Data Protection Agency (case number 2007-58-0010; date of approval: 01/28/2015). The trial was registered at http//www.clinicaltrials.gov (registration number: NCT02192216; date of registration 07/17-2014).
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Affiliation(s)
- Andreas Buch Møller
- Research Laboratory for Biochemical Pathology, Department of Clinical Medicine, HEALTH, Aarhus University Hospital, Palle Juul-Jensen Blvd., 8200, Aarhus N, Denmark.,Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
| | - Simon Lønbro
- Section of Sports Science, Department of Public Health, HEALTH, Aarhus University, Aarhus, Denmark.,Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Jean Farup
- Research Laboratory for Biochemical Pathology, Department of Clinical Medicine, HEALTH, Aarhus University Hospital, Palle Juul-Jensen Blvd., 8200, Aarhus N, Denmark
| | - Thomas Schmidt Voss
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark.,Medical Research Laboratory, Department of Clinical Medicine, HEALTH, Aarhus University, Aarhus, Denmark
| | - Nikolaj Rittig
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark.,Medical Research Laboratory, Department of Clinical Medicine, HEALTH, Aarhus University, Aarhus, Denmark
| | - Jakob Wang
- Section of Sports Science, Department of Public Health, HEALTH, Aarhus University, Aarhus, Denmark
| | - Inger Højris
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Ulla Ramer Mikkelsen
- Section of Sports Science, Department of Public Health, HEALTH, Aarhus University, Aarhus, Denmark.,Department of Orthopedic Surgery, Bispebjerg Hospital and Center for Healthy Aging, Institute of Sports Medicine, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark
| | - Niels Jessen
- Research Laboratory for Biochemical Pathology, Department of Clinical Medicine, HEALTH, Aarhus University Hospital, Palle Juul-Jensen Blvd., 8200, Aarhus N, Denmark. .,Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark. .,Department of Clinical Pharmacology, Aarhus University Hospital, Aarhus, Denmark.
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12
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Muise ES, Guan HP, Liu J, Nawrocki AR, Yang X, Wang C, Rodríguez CG, Zhou D, Gorski JN, Kurtz MM, Feng D, Leavitt KJ, Wei L, Wilkening RR, Apgar JM, Xu S, Lu K, Feng W, Li Y, He H, Previs SF, Shen X, van Heek M, Souza SC, Rosenbach MJ, Biftu T, Erion MD, Kelley DE, Kemp DM, Myers RW, Sebhat IK. Pharmacological AMPK activation induces transcriptional responses congruent to exercise in skeletal and cardiac muscle, adipose tissues and liver. PLoS One 2019; 14:e0211568. [PMID: 30811418 PMCID: PMC6392219 DOI: 10.1371/journal.pone.0211568] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 01/16/2019] [Indexed: 12/25/2022] Open
Abstract
Physical activity promotes metabolic and cardiovascular health benefits that derive in part from the transcriptional responses to exercise that occur within skeletal muscle and other organs. There is interest in discovering a pharmacologic exercise mimetic that could imbue wellness and alleviate disease burden. However, the molecular physiology by which exercise signals the transcriptional response is highly complex, making it challenging to identify a single target for pharmacological mimicry. The current studies evaluated the transcriptome responses in skeletal muscle, heart, liver, and white and brown adipose to novel small molecule activators of AMPK (pan-activators for all AMPK isoforms) compared to that of exercise. A striking level of congruence between exercise and pharmacological AMPK activation was observed across the induced transcriptome of these five tissues. However, differences in acute metabolic response between exercise and pharmacologic AMPK activation were observed, notably for acute glycogen balances and related to the energy expenditure induced by exercise but not pharmacologic AMPK activation. Nevertheless, intervention with repeated daily administration of short-acting activation of AMPK was found to mitigate hyperglycemia and hyperinsulinemia in four rodent models of metabolic disease and without the cardiac glycogen accretion noted with sustained pharmacologic AMPK activation. These findings affirm that activation of AMPK is a key node governing exercise mediated transcription and is an attractive target as an exercise mimetic.
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Affiliation(s)
- Eric S. Muise
- Genetics and Pharmacogenomics Department, MRL, Kenilworth, NJ, United States of America
- * E-mail: (ESM); (IKS)
| | - Hong-Ping Guan
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Jinqi Liu
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Andrea R. Nawrocki
- In Vivo Pharmacology Department, MRL, Kenilworth, NJ, United States of America
| | - Xiaodong Yang
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Chuanlin Wang
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Carlos G. Rodríguez
- In Vivo Pharmacology Department, MRL, Kenilworth, NJ, United States of America
| | - Dan Zhou
- In Vivo Pharmacology Department, MRL, Kenilworth, NJ, United States of America
| | - Judith N. Gorski
- In Vivo Pharmacology Department, MRL, Kenilworth, NJ, United States of America
| | - Marc M. Kurtz
- In Vitro PharmacologyDepartment, MRL, NJ, United States of America
| | - Danqing Feng
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
| | - Kenneth J. Leavitt
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
| | - Lan Wei
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
| | - Robert R. Wilkening
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
| | - James M. Apgar
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
| | - Shiyao Xu
- PPDM Preclinical ADME Department, MRL, Kenilworth, NJ, United States of America
| | - Ku Lu
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Wen Feng
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Ying Li
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Huaibing He
- PPDM Preclinical ADME Department, MRL, Kenilworth, NJ, United States of America
| | - Stephen F. Previs
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Xiaolan Shen
- SALAR Department, MRL, Kenilworth, NJ, United States of America
| | - Margaret van Heek
- In Vivo Pharmacology Department, MRL, Kenilworth, NJ, United States of America
| | - Sandra C. Souza
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Mark J. Rosenbach
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Tesfaye Biftu
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
| | - Mark D. Erion
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - David E. Kelley
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Daniel M. Kemp
- Biology-Discovery Department, MRL, Kenilworth, NJ, United States of America
| | - Robert W. Myers
- In Vitro PharmacologyDepartment, MRL, NJ, United States of America
| | - Iyassu K. Sebhat
- Medicinal ChemistryDepartment, MRL, Kenilworth, NJ, United States of America
- * E-mail: (ESM); (IKS)
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13
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Corrochano S, Blanco G, Williams D, Wettstein J, Simon M, Kumar S, Moir L, Agnew T, Stewart M, Landman A, Kotiadis VN, Duchen MR, Wackerhage H, Rubinsztein DC, Brown SDM, Acevedo-Arozena A. A genetic modifier suggests that endurance exercise exacerbates Huntington's disease. Hum Mol Genet 2019; 27:1723-1731. [PMID: 29509900 PMCID: PMC5932560 DOI: 10.1093/hmg/ddy077] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 02/22/2018] [Indexed: 12/19/2022] Open
Abstract
Polyglutamine expansions in the huntingtin gene cause Huntington's disease (HD). Huntingtin is ubiquitously expressed, leading to pathological alterations also in peripheral organs. Variations in the length of the polyglutamine tract explain up to 70% of the age-at-onset variance, with the rest of the variance attributed to genetic and environmental modifiers. To identify novel disease modifiers, we performed an unbiased mutagenesis screen on an HD mouse model, identifying a mutation in the skeletal muscle voltage-gated sodium channel (Scn4a, termed 'draggen' mutation) as a novel disease enhancer. Double mutant mice (HD; Scn4aDgn/+) had decreased survival, weight loss and muscle atrophy. Expression patterns show that the main tissue affected is skeletal muscle. Intriguingly, muscles from HD; Scn4aDgn/+ mice showed adaptive changes similar to those found in endurance exercise, including AMPK activation, fibre type switching and upregulation of mitochondrial biogenesis. Therefore, we evaluated the effects of endurance training on HD mice. Crucially, this training regime also led to detrimental effects on HD mice. Overall, these results reveal a novel role for skeletal muscle in modulating systemic HD pathogenesis, suggesting that some forms of physical exercise could be deleterious in neurodegeneration.
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Affiliation(s)
- Silvia Corrochano
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | | | - Debbie Williams
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | | | - Michelle Simon
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Saumya Kumar
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Lee Moir
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Thomas Agnew
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Michelle Stewart
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Allison Landman
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Vassilios N Kotiadis
- Department of Cell and Developmental Biology, University College London (UCL), London, UK
| | - Michael R Duchen
- Department of Cell and Developmental Biology, University College London (UCL), London, UK
| | - Henning Wackerhage
- Institute of Medical Sciences, University of Aberdeen, Scotland, UK.,Department of Sport and Health Sciences, Technical University of Munich (TUM), Exercise Biology, Munich, Germany
| | - David C Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, UK.,UK Dementia Research Institute, University of Cambridge, Cambridge, UK
| | - Steve D M Brown
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK
| | - Abraham Acevedo-Arozena
- Mammalian Genetics Unit, Harwell Institute, Medical Research Council, Oxfordshire, UK.,Unidad de Investigación, Hospital Universitario de Canarias, Fundación Canaria de Investigación Sanitaria e Instituto de Tecnologías Biomédicas, La Laguna, Spain
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14
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Metformin; an old antidiabetic drug with new potentials in bone disorders. Biomed Pharmacother 2018; 109:1593-1601. [PMID: 30551413 DOI: 10.1016/j.biopha.2018.11.032] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 11/05/2018] [Accepted: 11/07/2018] [Indexed: 01/15/2023] Open
Abstract
The prevalence of diabetes mellitus especially type 2 diabetes mellitus is increasing all over the world. In addition to cardiomyopathy and nephropathy, diabetics are at higher risk of mortality and morbidity due to greater risk of bone fractures and skeletal abnormalities. Patients with diabetes mellitus have lower bone quality in comparison to their non-diabetic counterparts mainly because of hyperglycemia, toxic effects of advanced glycosylation end-products (AGEs) on bone tissue, and impaired bone microvascular system. AGEs may also contribute to the development of osteoarthritis further to osteoporosis. Therefore, glycemic control in diabetic patients is vital for bone health. Metformin, a widely used antidiabetic drug, has been shown to improve bone quality and decrease the risk of fractures in patients with diabetes in addition to glycemic control and improving insulin sensitivity. AMP activated protein kinase (AMPK), the key molecule in metformin antidiabetic mechanism of action, is also effective in signaling pathways involved in bone physiology. This review, discusses the molecules linking diabetes and bone turnover, role of AMPK in bone metabolism, and the effect of metformin as an activator of AMPK on bone disorders and malignancies.
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15
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Steenberg DE, Jørgensen NB, Birk JB, Sjøberg KA, Kiens B, Richter EA, Wojtaszewski JFP. Exercise training reduces the insulin-sensitizing effect of a single bout of exercise in human skeletal muscle. J Physiol 2018; 597:89-103. [PMID: 30325018 DOI: 10.1113/jp276735] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 10/11/2018] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS A single bout of exercise is capable of increasing insulin sensitivity in human skeletal muscle. Whether this ability is affected by training status is not clear. Studies in mice suggest that the AMPK-TBC1D4 signalling axis is important for the increased insulin-stimulated glucose uptake after a single bout of exercise. The present study is the first longitudinal intervention study to show that, although exercise training increases insulin-stimulated glucose uptake in skeletal muscle at rest, it diminishes the ability of a single bout of exercise to enhance muscle insulin-stimulated glucose uptake. The present study provides novel data indicating that AMPK in human skeletal muscle is important for the insulin-sensitizing effect of a single bout of exercise. ABSTRACT Not only chronic exercise training, but also a single bout of exercise, increases insulin-stimulated glucose uptake in skeletal muscle. However, it is not well described how adaptations to exercise training affect the ability of a single bout of exercise to increase insulin sensitivity. Rodent studies suggest that the insulin-sensitizing effect of a single bout of exercise is AMPK-dependent (presumably via the α2 β2 γ3 AMPK complex). Whether this is also the case in humans is unknown. Previous studies have shown that exercise training decreases the expression of the α2 β2 γ3 AMPK complex and diminishes the activation of this complex during exercise. Thus, we hypothesized that exercise training diminishes the ability of a single bout of exercise to enhance muscle insulin sensitivity. We investigated nine healthy male subjects who performed one-legged knee-extensor exercise at the same relative intensity before and after 12 weeks of exercise training. Training increased V ̇ O 2 peak and expression of mitochondrial proteins in muscle, whereas the expression of AMPKγ3 was decreased. Training also increased whole body and muscle insulin sensitivity. Interestingly, insulin-stimulated glucose uptake in the acutely exercised leg was not enhanced further by training. Thus, the increase in insulin-stimulated glucose uptake following a single bout of one-legged exercise was lower in the trained vs. untrained state. This was associated with reduced signalling via confirmed α2 β2 γ3 AMPK downstream targets (ACC and TBC1D4). These results suggest that the insulin-sensitizing effect of a single bout of exercise is also AMPK-dependent in human skeletal muscle.
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Affiliation(s)
- Dorte E Steenberg
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Nichlas B Jørgensen
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Jesper B Birk
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Kim A Sjøberg
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Erik A Richter
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, University of Copenhagen, Copenhagen, Denmark
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16
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The Role of AMPK in the Regulation of Skeletal Muscle Size, Hypertrophy, and Regeneration. Int J Mol Sci 2018; 19:ijms19103125. [PMID: 30314396 PMCID: PMC6212977 DOI: 10.3390/ijms19103125] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 12/22/2022] Open
Abstract
AMPK (5’-adenosine monophosphate-activated protein kinase) is heavily involved in skeletal muscle metabolic control through its regulation of many downstream targets. Because of their effects on anabolic and catabolic cellular processes, AMPK plays an important role in the control of skeletal muscle development and growth. In this review, the effects of AMPK signaling, and those of its upstream activator, liver kinase B1 (LKB1), on skeletal muscle growth and atrophy are reviewed. The effect of AMPK activity on satellite cell-mediated muscle growth and regeneration after injury is also reviewed. Together, the current data indicate that AMPK does play an important role in regulating muscle mass and regeneration, with AMPKα1 playing a prominent role in stimulating anabolism and in regulating satellite cell dynamics during regeneration, and AMPKα2 playing a potentially more important role in regulating muscle degradation during atrophy.
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17
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Isoform-specific AMPK association with TBC1D1 is reduced by a mutation associated with severe obesity. Biochem J 2018; 475:2969-2983. [PMID: 30135087 PMCID: PMC6156765 DOI: 10.1042/bcj20180475] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/10/2018] [Accepted: 08/22/2018] [Indexed: 01/08/2023]
Abstract
AMP-activated protein kinase (AMPK) is a key regulator of cellular and systemic energy homeostasis which achieves this through the phosphorylation of a myriad of downstream targets. One target is TBC1D1 a Rab-GTPase-activating protein that regulates glucose uptake in muscle cells by integrating insulin signalling with that promoted by muscle contraction. Ser237 in TBC1D1 is a target for phosphorylation by AMPK, an event which may be important in regulating glucose uptake. Here, we show AMPK heterotrimers containing the α1, but not the α2, isoform of the catalytic subunit form an unusual and stable association with TBC1D1, but not its paralogue AS160. The interaction between the two proteins is direct, involves a dual interaction mechanism employing both phosphotyrosine-binding (PTB) domains of TBC1D1 and is increased by two different pharmacological activators of AMPK (AICAR and A769962). The interaction enhances the efficiency by which AMPK phosphorylates TBC1D1 on its key regulatory site, Ser237. Furthermore, the interaction is reduced by a naturally occurring R125W mutation in the PTB1 domain of TBC1D1, previously found to be associated with severe familial obesity in females, with a concomitant reduction in Ser237 phosphorylation. Our observations provide evidence for a functional difference between AMPK α-subunits and extend the repertoire of protein kinases that interact with substrates via stabilisation mechanisms that modify the efficacy of substrate phosphorylation.
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18
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Popov DV, Lysenko EA, Bokov RO, Volodina MA, Kurochkina NS, Makhnovskii PA, Vyssokikh MY, Vinogradova OL. Effect of aerobic training on baseline expression of signaling and respiratory proteins in human skeletal muscle. Physiol Rep 2018; 6:e13868. [PMID: 30198217 PMCID: PMC6129775 DOI: 10.14814/phy2.13868] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/24/2018] [Indexed: 12/30/2022] Open
Abstract
Most studies examining the molecular mechanisms underlying adaptation of human skeletal muscles to aerobic exercise focused on the response to acute exercise. Here, we examined the effect of a 2-month aerobic training program on baseline parameters in human muscle. Ten untrained males performed a one-legged knee extension exercise for 1 h with the same relative intensity before and after a 2-month aerobic training program. Biopsy samples were taken from vastus lateralis muscle at rest before and after the 2 month training program (baseline samples). Additionally, biopsy samples were taken from the exercised leg 1 and 4 h after the one-legged continuous knee extension exercise. Aerobic training decreases baseline phosphorylation of FOXO1Ser256 , increases that of CaMKIIThr286 , CREB1Ser133 , increases baseline expression of mitochondrial proteins in respiratory complexes I-V, and some regulators of mitochondrial biogenesis (TFAM, NR4A3, and CRTC2). An increase in the baseline content of these proteins was not associated with a change in baseline expression of their genes. The increase in the baseline content of regulators of mitochondrial biogenesis (TFAM and NR4A3) was associated with a transient increase in transcription after acute exercise. Contrariwise, the increase in the baseline content of respiratory proteins does not seem to be regulated at the transcriptional level; rather, it is associated with other mechanisms. Adaptation of human skeletal muscle to regular aerobic exercise is associated not only with transient molecular responses to exercise, but also with changes in baseline phosphorylation and expression of regulatory proteins.
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Affiliation(s)
- Daniil V. Popov
- Laboratory of Exercise PhysiologyInstitute of Biomedical Problems of the Russian Academy of SciencesMoscowRussia
- Faculty of Fundamental MedicineM.V. Lomonosov Moscow State UniversityMoscowRussia
| | - Evgeny A. Lysenko
- Laboratory of Exercise PhysiologyInstitute of Biomedical Problems of the Russian Academy of SciencesMoscowRussia
- Faculty of Fundamental MedicineM.V. Lomonosov Moscow State UniversityMoscowRussia
| | - Roman O. Bokov
- Laboratory of Exercise PhysiologyInstitute of Biomedical Problems of the Russian Academy of SciencesMoscowRussia
| | - Maria A. Volodina
- Laboratory of Mitochondrial MedicineResearch Center for ObstetricsGynecology and PerinatologyMinistry of Healthcare of the Russian FederationMoscowRussia
| | - Nadia S. Kurochkina
- Laboratory of Exercise PhysiologyInstitute of Biomedical Problems of the Russian Academy of SciencesMoscowRussia
| | - Pavel A. Makhnovskii
- Laboratory of Exercise PhysiologyInstitute of Biomedical Problems of the Russian Academy of SciencesMoscowRussia
| | - Mikhail Y. Vyssokikh
- Laboratory of Mitochondrial MedicineResearch Center for ObstetricsGynecology and PerinatologyMinistry of Healthcare of the Russian FederationMoscowRussia
| | - Olga L. Vinogradova
- Laboratory of Exercise PhysiologyInstitute of Biomedical Problems of the Russian Academy of SciencesMoscowRussia
- Faculty of Fundamental MedicineM.V. Lomonosov Moscow State UniversityMoscowRussia
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19
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Muscle health and performance in monozygotic twins with 30 years of discordant exercise habits. Eur J Appl Physiol 2018; 118:2097-2110. [PMID: 30006671 DOI: 10.1007/s00421-018-3943-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/10/2018] [Indexed: 01/05/2023]
Abstract
INTRODUCTION Physical health and function depend upon both genetic inheritance and environmental factors (e.g., exercise training). PURPOSE To enhance the understanding of heritability/adaptability, we explored the skeletal muscle health and physiological performance of monozygotic (MZ) twins with > 30 years of chronic endurance training vs. no specific/consistent exercise. METHODS One pair of male MZ twins (age = 52 years; Trained Twin, TT; Untrained Twin, UT) underwent analyses of: (1) anthropometric characteristics and blood profiles, (2) markers of cardiovascular and pulmonary health, and (3) skeletal muscle size, strength, and power and molecular markers of muscle health. RESULTS This case study represents the most comprehensive physiological comparison of MZ twins with this length and magnitude of differing exercise history. TT exhibited: (1) lower body mass, body fat%, resting heart rate, blood pressure, cholesterol, triglycerides, and plasma glucose, (2) greater relative cycling power, anaerobic endurance, and aerobic capacity (VO2max), but lower muscle size/strength and poorer muscle quality, (3) more MHC I (slow-twitch) and fewer MHC IIa (fast-twitch) fibers, (4) greater AMPK protein expression, and (5) greater PAX7, IGF1Ec, IGF1Ea, and FN14 mRNA expression than UT. CONCLUSIONS Several measured differences are the largest reported between MZ twins (TT expressed 55% more MHC I fibers, 12.4 ml/kg/min greater VO2max, and 8.6% lower body fat% vs. UT). These data collectively (a) support utilizing chronic endurance training to improve body composition and cardiovascular health and (b) suggest the cardiovascular and skeletal muscle systems exhibit greater plasticity than previously thought, further highlighting the importance of studying MZ twins with large (long-term) differences in exposomes.
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20
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Kjøbsted R, Hingst JR, Fentz J, Foretz M, Sanz MN, Pehmøller C, Shum M, Marette A, Mounier R, Treebak JT, Wojtaszewski JFP, Viollet B, Lantier L. AMPK in skeletal muscle function and metabolism. FASEB J 2018; 32:1741-1777. [PMID: 29242278 PMCID: PMC5945561 DOI: 10.1096/fj.201700442r] [Citation(s) in RCA: 275] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Skeletal muscle possesses a remarkable ability to adapt to various physiologic conditions. AMPK is a sensor of intracellular energy status that maintains energy stores by fine-tuning anabolic and catabolic pathways. AMPK’s role as an energy sensor is particularly critical in tissues displaying highly changeable energy turnover. Due to the drastic changes in energy demand that occur between the resting and exercising state, skeletal muscle is one such tissue. Here, we review the complex regulation of AMPK in skeletal muscle and its consequences on metabolism (e.g., substrate uptake, oxidation, and storage as well as mitochondrial function of skeletal muscle fibers). We focus on the role of AMPK in skeletal muscle during exercise and in exercise recovery. We also address adaptations to exercise training, including skeletal muscle plasticity, highlighting novel concepts and future perspectives that need to be investigated. Furthermore, we discuss the possible role of AMPK as a therapeutic target as well as different AMPK activators and their potential for future drug development.—Kjøbsted, R., Hingst, J. R., Fentz, J., Foretz, M., Sanz, M.-N., Pehmøller, C., Shum, M., Marette, A., Mounier, R., Treebak, J. T., Wojtaszewski, J. F. P., Viollet, B., Lantier, L. AMPK in skeletal muscle function and metabolism.
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Affiliation(s)
- Rasmus Kjøbsted
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Janne R Hingst
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Joachim Fentz
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Marc Foretz
- INSERM, Unité 1016, Institut Cochin, Paris, France.,Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Maria-Nieves Sanz
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland, and.,Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Christian Pehmøller
- Internal Medicine Research Unit, Pfizer Global Research and Development, Cambridge, Massachusetts, USA
| | - Michael Shum
- Axe Cardiologie, Quebec Heart and Lung Research Institute, Laval University, Québec, Canada.,Institute for Nutrition and Functional Foods, Laval University, Québec, Canada
| | - André Marette
- Axe Cardiologie, Quebec Heart and Lung Research Institute, Laval University, Québec, Canada.,Institute for Nutrition and Functional Foods, Laval University, Québec, Canada
| | - Remi Mounier
- Institute NeuroMyoGène, Université Claude Bernard Lyon 1, INSERM Unité 1217, CNRS UMR, Villeurbanne, France
| | - Jonas T Treebak
- Section of Integrative Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Benoit Viollet
- INSERM, Unité 1016, Institut Cochin, Paris, France.,Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Louise Lantier
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA.,Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee, USA
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21
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Kjøbsted R, Wojtaszewski JFP, Treebak JT. Role of AMP-Activated Protein Kinase for Regulating Post-exercise Insulin Sensitivity. ACTA ACUST UNITED AC 2017; 107:81-126. [PMID: 27812978 DOI: 10.1007/978-3-319-43589-3_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Skeletal muscle insulin resistance precedes development of type 2 diabetes (T2D). As skeletal muscle is a major sink for glucose disposal, understanding the molecular mechanisms involved in maintaining insulin sensitivity of this tissue could potentially benefit millions of people that are diagnosed with insulin resistance. Regular physical activity in both healthy and insulin-resistant individuals is recognized as the single most effective intervention to increase whole-body insulin sensitivity and thereby positively affect glucose homeostasis. A single bout of exercise has long been known to increase glucose disposal in skeletal muscle in response to physiological insulin concentrations. While this effect is identified to be restricted to the previously exercised muscle, the molecular basis for an apparent convergence between exercise- and insulin-induced signaling pathways is incompletely known. In recent years, we and others have identified the Rab GTPase-activating protein, TBC1 domain family member 4 (TBC1D4) as a target of key protein kinases in the insulin- and exercise-activated signaling pathways. Our working hypothesis is that the AMP-activated protein kinase (AMPK) is important for the ability of exercise to insulin sensitize skeletal muscle through TBC1D4. Here, we aim to provide an overview of the current available evidence linking AMPK to post-exercise insulin sensitivity.
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Affiliation(s)
- Rasmus Kjøbsted
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark.
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22
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Sylow L, Kleinert M, Richter EA, Jensen TE. Exercise-stimulated glucose uptake - regulation and implications for glycaemic control. Nat Rev Endocrinol 2017; 13:133-148. [PMID: 27739515 DOI: 10.1038/nrendo.2016.162] [Citation(s) in RCA: 265] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Skeletal muscle extracts glucose from the blood to maintain demand for carbohydrates as an energy source during exercise. Such uptake involves complex molecular signalling processes that are distinct from those activated by insulin. Exercise-stimulated glucose uptake is preserved in insulin-resistant muscle, emphasizing exercise as a therapeutic cornerstone among patients with metabolic diseases such as diabetes mellitus. Exercise increases uptake of glucose by up to 50-fold through the simultaneous stimulation of three key steps: delivery, transport across the muscle membrane and intracellular flux through metabolic processes (glycolysis and glucose oxidation). The available data suggest that no single signal transduction pathway can fully account for the regulation of any of these key steps, owing to redundancy in the signalling pathways that mediate glucose uptake to ensure maintenance of muscle energy supply during physical activity. Here, we review the molecular mechanisms that regulate the movement of glucose from the capillary bed into the muscle cell and discuss what is known about their integrated regulation during exercise. Novel developments within the field of mass spectrometry-based proteomics indicate that the known regulators of glucose uptake are only the tip of the iceberg. Consequently, many exciting discoveries clearly lie ahead.
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Affiliation(s)
- Lykke Sylow
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Maximilian Kleinert
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Erik A Richter
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E Jensen
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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23
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Abstract
Activation of the adenosine monophosphate (AMP)-activated kinase (AMPK) contributes to beneficial effects such as improvement of the hyperglycemic state in diabetes as well as reduction of obesity and inflammatory processes. Furthermore, stimulation of AMPK activity has been associated with increased exercise capacity. A study published in 2008, directly before the Olympic Games in Beijing, showed that the AMPK activator AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide) increased the running capacity of mice without any training and thus, prompted the World Anti-Doping Agency (WADA) to include certain AMPK activators in the list of forbidden drugs. This raises the question as to whether all AMPK activators should be considered for registration or whether the increase in exercise performance is only associated with specific AMPK-activating substances. In this review, we intend to shed light on currently published AMPK-activating drugs, their working mechanisms, and their impact on body fitness.
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24
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Understanding Muscle Dysfunction in Chronic Fatigue Syndrome. J Aging Res 2016; 2016:2497348. [PMID: 26998359 PMCID: PMC4779819 DOI: 10.1155/2016/2497348] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/12/2015] [Accepted: 01/13/2016] [Indexed: 12/11/2022] Open
Abstract
Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME.
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25
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Thomassen M, Gunnarsson TP, Christensen PM, Pavlovic D, Shattock MJ, Bangsbo J. Intensive training and reduced volume increases muscle FXYD1 expression and phosphorylation at rest and during exercise in athletes. Am J Physiol Regul Integr Comp Physiol 2016; 310:R659-69. [PMID: 26791827 DOI: 10.1152/ajpregu.00081.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 01/18/2016] [Indexed: 01/10/2023]
Abstract
The present study examined the effect of intensive training in combination with marked reduction in training volume on phospholemman (FXYD1) expression and phosphorylation at rest and during exercise. Eight well-trained cyclists replaced their regular training with speed-endurance training (10-12 × ∼30-s sprints) two or three times per week and aerobic high-intensity training (4-5 × 3-4 min at 90-95% of peak aerobic power output) 1-2 times per week for 7 wk and reduced the training volume by 70%. Muscle biopsies were obtained before and during a repeated high-intensity exercise protocol, and protein expression and phosphorylation were determined by Western blot analysis. Expression of FXYD1 (30%), actin (40%), mammalian target of rapamycin (mTOR) (12%), phospholamban (PLN) (16%), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) γ/δ (25%) was higher (P < 0.05) than before the training intervention. In addition, after the intervention, nonspecific FXYD1 phosphorylation was higher (P < 0.05) at rest and during exercise, mainly achieved by an increased FXYD1 Ser-68 phosphorylation, compared with before the intervention. CaMKII, Thr-287, and eukaryotic elongation factor 2 Thr-56 phosphorylation at rest and during exercise, overall PKCα/β, Thr-638/641, and mTOR Ser-2448 phosphorylation during repeated intense exercise as well as resting PLN Thr-17 phosphorylation were also higher (P < 0.05) compared with before the intervention period. Thus, a period of high-intensity training with reduced training volume increases expression and phosphorylation levels of FXYD1, which may affect Na(+)/K(+) pump activity and muscle K(+) homeostasis during intense exercise. Furthermore, higher expression of CaMKII and PLN, as well as increased phosphorylation of CaMKII Thr-287 may have improved intracellular Ca(2+) handling.
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Affiliation(s)
- Martin Thomassen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Thomas P Gunnarsson
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Peter M Christensen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Davor Pavlovic
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Michael J Shattock
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
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26
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Fritzen AM, Madsen AB, Kleinert M, Treebak JT, Lundsgaard AM, Jensen TE, Richter EA, Wojtaszewski J, Kiens B, Frøsig C. Regulation of autophagy in human skeletal muscle: effects of exercise, exercise training and insulin stimulation. J Physiol 2016; 594:745-61. [PMID: 26614120 DOI: 10.1113/jp271405] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/25/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Regulation of autophagy in human muscle in many aspects differs from the majority of previous reports based on studies in cell systems and rodent muscle. An acute bout of exercise and insulin stimulation reduce human muscle autophagosome content. An acute bout of exercise regulates autophagy by a local contraction-induced mechanism. Exercise training increases the capacity for formation of autophagosomes in human muscle. AMPK activation during exercise seems insufficient to regulate autophagosome content in muscle, while mTORC1 signalling via ULK1 probably mediates the autophagy-inhibiting effect of insulin. Studies in rodent muscle suggest that autophagy is regulated by acute exercise, exercise training and insulin stimulation. However, little is known about the regulation of autophagy in human skeletal muscle. Here we investigate the autophagic response to acute one-legged exercise, one-legged exercise training and subsequent insulin stimulation in exercised and non-exercised human muscle. Acute one-legged exercise decreased (P<0.01) lipidation of microtubule-associated protein 1A/1B-light chain 3 (LC3) (∼ 50%) and the LC3-II/LC3-I ratio (∼ 60%) indicating that content of autophagosomes decreases with exercise in human muscle. The decrease in LC3-II/LC3-I ratio did not correlate with activation of 5'AMP activated protein kinase (AMPK) trimer complexes in human muscle. Consistently, pharmacological AMPK activation with 5-aminoimidazole-4-carboxamide riboside (AICAR) in mouse muscle did not affect the LC3-II/LC3-I ratio. Four hours after exercise, insulin further reduced (P<0.01) the LC3-II/LC3-I ratio (∼ 80%) in muscle of the exercised and non-exercised leg in humans. This coincided with increased Ser-757 phosphorylation of Unc51 like kinase 1 (ULK1), which is suggested as a mammalian target of rapamycin complex 1 (mTORC1) target. Accordingly, inhibition of mTOR signalling in mouse muscle prevented the ability of insulin to reduce the LC3-II/LC3-I ratio. In response to 3 weeks of one-legged exercise training, the LC3-II/LC3-I ratio decreased (P<0.05) in both trained and untrained muscle and this change was largely driven by an increase in LC3-I content. Taken together, acute exercise and insulin stimulation reduce muscle autophagosome content, while exercise training may increase the capacity for formation of autophagosomes in muscle. Moreover, AMPK activation during exercise may not be sufficient to regulate autophagy in muscle, while mTORC1 signalling via ULK1 probably mediates the autophagy-inhibiting effect of insulin.
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Affiliation(s)
- Andreas M Fritzen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Agnete B Madsen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Maximilian Kleinert
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jonas T Treebak
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.,The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anne-Marie Lundsgaard
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Erik A Richter
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Christian Frøsig
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, the August Krogh Centre, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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27
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Prior SJ, Goldberg AP, Ortmeyer HK, Chin ER, Chen D, Blumenthal JB, Ryan AS. Increased Skeletal Muscle Capillarization Independently Enhances Insulin Sensitivity in Older Adults After Exercise Training and Detraining. Diabetes 2015; 64:3386-95. [PMID: 26068543 PMCID: PMC4587640 DOI: 10.2337/db14-1771] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 05/23/2015] [Indexed: 01/04/2023]
Abstract
Intramuscular signaling and glucose transport mechanisms contribute to improvements in insulin sensitivity after aerobic exercise training. This study tested the hypothesis that increases in skeletal muscle capillary density (CD) also contribute to exercise-induced improvements in whole-body insulin sensitivity (insulin-stimulated glucose uptake per unit plasma insulin [M/I]) independent of other mechanisms. The study design included a 6-month aerobic exercise training period followed by a 2-week detraining period to eliminate short-term effects of exercise on intramuscular signaling and glucose transport. Before and after exercise training and detraining, 12 previously sedentary older (65 ± 3 years) men and women underwent research tests, including hyperinsulinemic-euglycemic clamps and vastus lateralis biopsies. Exercise training increased Vo2max (2.2 ± 0.2 vs. 2.5 ± 0.2 L/min), CD (313 ± 13 vs. 349 ± 18 capillaries/mm(2)), and M/I (0.041 ± 0.005 vs. 0.051 ± 0.007 μmol/kg fat-free mass/min) (P < 0.05 for all). Exercise training also increased the insulin activation of glycogen synthase by 60%, GLUT4 expression by 16%, and 5' AMPK-α1 expression by 21%, but these reverted to baseline levels after detraining. Conversely, CD and M/I remained 15% and 18% higher after detraining, respectively (P < 0.05), and the changes in M/I (detraining minus baseline) correlated directly with changes in CD in regression analysis (partial r = 0.70; P = 0.02). These results suggest that an increase in CD is one mechanism contributing to sustained improvements in glucose metabolism after aerobic exercise training.
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Affiliation(s)
- Steven J Prior
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD Baltimore Veterans Affairs Geriatric Research Education and Clinical Center and Research and Development Service, Baltimore, MD
| | - Andrew P Goldberg
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD Baltimore Veterans Affairs Geriatric Research Education and Clinical Center and Research and Development Service, Baltimore, MD
| | - Heidi K Ortmeyer
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD Baltimore Veterans Affairs Geriatric Research Education and Clinical Center and Research and Development Service, Baltimore, MD
| | - Eva R Chin
- Department of Kinesiology, University of Maryland School of Public Health, College Park, MD
| | - Dapeng Chen
- Department of Kinesiology, University of Maryland School of Public Health, College Park, MD
| | - Jacob B Blumenthal
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD Baltimore Veterans Affairs Geriatric Research Education and Clinical Center and Research and Development Service, Baltimore, MD
| | - Alice S Ryan
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD Baltimore Veterans Affairs Geriatric Research Education and Clinical Center and Research and Development Service, Baltimore, MD
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28
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Abstract
The past 25 years have witnessed major advances in our knowledge of how exercise activates cellular, molecular, and biochemical pathways with regulatory roles in training response adaptation, and how muscle "cross-talk" with other organs is a mechanism by which physical activity exerts its beneficial effects on "whole-body" health. However, during the late 19(th) and early 20(th) centuries, scientific debate in the field of exercise metabolism centered on questions related to the sources of energy for muscular activity, diet-exercise manipulations to alter patterns of fuel utilization, as well as the factors limiting physical work capacity. Posing novel scientific questions and utilizing cutting-edge techniques, the contributions made by the great pioneers of the 19(th) and early 20(th) centuries laid the foundation on which much of our present knowledge of exercise metabolism is based and paved the way for future discoveries in the field.
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29
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Kjøbsted R, Treebak JT, Fentz J, Lantier L, Viollet B, Birk JB, Schjerling P, Björnholm M, Zierath JR, Wojtaszewski JFP. Prior AICAR stimulation increases insulin sensitivity in mouse skeletal muscle in an AMPK-dependent manner. Diabetes 2015; 64:2042-55. [PMID: 25552597 DOI: 10.2337/db14-1402] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 12/20/2014] [Indexed: 11/13/2022]
Abstract
An acute bout of exercise increases glucose uptake in skeletal muscle by an insulin-independent mechanism. In the period after exercise, insulin sensitivity to increased glucose uptake is enhanced. The molecular mechanisms underpinning this phenomenon are poorly understood but appear to involve an increased cell surface abundance of GLUT4. While increased proximal insulin signaling does not seem to mediate this effect, elevated phosphorylation of TBC1D4, a downstream target of both insulin (Akt) and exercise (AMPK) signaling, appears to play a role. The main purpose of this study was to determine whether AMPK activation increases skeletal muscle insulin sensitivity. We found that prior AICAR stimulation of wild-type mouse muscle increases insulin sensitivity to stimulate glucose uptake. However, this was not observed in mice with reduced or ablated AMPK activity in skeletal muscle. Furthermore, prior AICAR stimulation enhanced insulin-stimulated phosphorylation of TBC1D4 at Thr(649) and Ser(711) in wild-type muscle only. These phosphorylation events were positively correlated with glucose uptake. Our results provide evidence to support that AMPK activation is sufficient to increase skeletal muscle insulin sensitivity. Moreover, TBC1D4 phosphorylation may facilitate the effect of prior AMPK activation to enhance glucose uptake in response to insulin.
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Affiliation(s)
- Rasmus Kjøbsted
- Section of Molecular Physiology, August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Jonas T Treebak
- Section of Molecular Physiology, August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Joachim Fentz
- Section of Molecular Physiology, August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Louise Lantier
- INSERM, U1016, Institut Cochin, Paris, France CNRS, UMR8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Benoit Viollet
- INSERM, U1016, Institut Cochin, Paris, France CNRS, UMR8104, Paris, France Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jesper B Birk
- Section of Molecular Physiology, August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Peter Schjerling
- Institute of Sports Medicine, Department of Orthopedic Surgery, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marie Björnholm
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Juleen R Zierath
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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30
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Møller AB, Vendelbo MH, Christensen B, Clasen BF, Bak AM, Jørgensen JOL, Møller N, Jessen N. Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle. J Appl Physiol (1985) 2015; 118:971-9. [DOI: 10.1152/japplphysiol.01116.2014] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 02/10/2015] [Indexed: 12/18/2022] Open
Abstract
Data from transgenic animal models suggest that exercise-induced autophagy is critical for adaptation to physical training, and that Unc-51 like kinase-1 (ULK1) serves as an important regulator of autophagy. Phosphorylation of ULK1 at Ser555 stimulates autophagy, whereas phosphorylation at Ser757 is inhibitory. To determine whether exercise regulates ULK1 phosphorylation in humans in vivo in a nutrient-dependent manner, we examined skeletal muscle biopsies from healthy humans after 1-h cycling exercise at 50% maximal O2 uptake on two occasions: 1) during a 36-h fast, and 2) during continuous glucose infusion at 0.2 kg/h. Physical exercise increased ULK1 phosphorylation at Ser555 and decreased lipidation of light chain 3B. ULK1 phosphorylation at Ser555 correlated positively with AMP-activated protein kinase-α Thr172 phosphorylation and negatively with light chain 3B lipidation. ULK1 phosphorylation at Ser757 was not affected by exercise. Fasting increased ULK1 and p62 protein expression, but did not affect exercise-induced ULK1 phosphorylation. These data demonstrate that autophagy signaling is activated in human skeletal muscle after 60 min of exercise, independently of nutritional status, and suggest that initiation of autophagy constitutes an important physiological response to exercise in humans.
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Affiliation(s)
- Andreas Buch Møller
- Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Mikkel Holm Vendelbo
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark; and
| | - Britt Christensen
- Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Berthil Forrest Clasen
- Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Ann Mosegaard Bak
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Jens O. L. Jørgensen
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Møller
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Jessen
- Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
- Medical Research Laboratory, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark
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31
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Brandauer J, Andersen MA, Kellezi H, Risis S, Frøsig C, Vienberg SG, Treebak JT. AMP-activated protein kinase controls exercise training- and AICAR-induced increases in SIRT3 and MnSOD. Front Physiol 2015; 6:85. [PMID: 25852572 PMCID: PMC4371692 DOI: 10.3389/fphys.2015.00085] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 03/04/2015] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial protein deacetylase sirtuin (SIRT) 3 may mediate exercise training-induced increases in mitochondrial biogenesis and improvements in reactive oxygen species (ROS) handling. We determined the requirement of AMP-activated protein kinase (AMPK) for exercise training-induced increases in skeletal muscle abundance of SIRT3 and other mitochondrial proteins. Exercise training for 6.5 weeks increased SIRT3 (p < 0.01) and superoxide dismutase 2 (MnSOD; p < 0.05) protein abundance in quadriceps muscle of wild-type (WT; n = 13–15), but not AMPK α2 kinase dead (KD; n = 12–13) mice. We also observed a strong trend for increased MnSOD abundance in exercise-trained skeletal muscle of healthy humans (p = 0.051; n = 6). To further elucidate a role for AMPK in mediating these effects, we treated WT (n = 7–8) and AMPK α2 KD (n = 7–9) mice with 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR). Four weeks of daily AICAR injections (500 mg/kg) resulted in AMPK-dependent increases in SIRT3 (p < 0.05) and MnSOD (p < 0.01) in WT, but not AMPK α2 KD mice. We also tested the effect of repeated AICAR treatment on mitochondrial protein levels in mice lacking the transcriptional coactivator peroxisome proliferator-activated receptor γ-coactivator 1α (PGC-1α KO; n = 9–10). Skeletal muscle SIRT3 and MnSOD protein abundance was reduced in sedentary PGC-1α KO mice (p < 0.01) and AICAR-induced increases in SIRT3 and MnSOD protein abundance was only observed in WT mice (p < 0.05). Finally, the acetylation status of SIRT3 target lysine residues on MnSOD (K122) or oligomycin-sensitivity conferring protein (OSCP; K139) was not altered in either mouse or human skeletal muscle in response to acute exercise. We propose an important role for AMPK in regulating mitochondrial function and ROS handling in skeletal muscle in response to exercise training.
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Affiliation(s)
- Josef Brandauer
- Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen Copenhagen, Denmark ; Department of Health Sciences, Gettysburg College Gettysburg, PA, USA
| | - Marianne A Andersen
- Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen Copenhagen, Denmark
| | - Holti Kellezi
- Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen Copenhagen, Denmark
| | - Steve Risis
- Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen Copenhagen, Denmark
| | - Christian Frøsig
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, The August Krogh Centre, University of Copenhagen Copenhagen, Denmark
| | - Sara G Vienberg
- Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen Copenhagen, Denmark
| | - Jonas T Treebak
- Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen Copenhagen, Denmark
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Kristensen DE, Albers PH, Prats C, Baba O, Birk JB, Wojtaszewski JFP. Human muscle fibre type-specific regulation of AMPK and downstream targets by exercise. J Physiol 2015; 593:2053-69. [PMID: 25640469 DOI: 10.1113/jphysiol.2014.283267] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/23/2015] [Indexed: 11/08/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a regulator of energy homeostasis during exercise. Studies suggest muscle fibre type-specific AMPK expression. However, fibre type-specific regulation of AMPK and downstream targets during exercise has not been demonstrated. We hypothesized that AMPK subunits are expressed in a fibre type-dependent manner and that fibre type-specific activation of AMPK and downstream targets is dependent on exercise intensity. Pools of type I and II fibres were prepared from biopsies of vastus lateralis muscle from healthy men before and after two exercise trials: (1) continuous cycling (CON) for 30 min at 69 ± 1% peak rate of O2 consumption (V̇O2 peak ) or (2) interval cycling (INT) for 30 min with 6 × 1.5 min high-intensity bouts peaking at 95 ± 2% V̇O2 peak . In type I vs. II fibres a higher β1 AMPK (+215%) and lower γ3 AMPK expression (-71%) was found. α1 , α2 , β2 and γ1 AMPK expression was similar between fibre types. In type I vs. II fibres phosphoregulation after CON was similar (AMPK(Thr172) , ACC(Ser221) , TBC1D1(Ser231) and GS(2+2a) ) or lower (TBC1D4(Ser704) ). Following INT, phosphoregulation in type I vs. II fibres was lower (AMPK(Thr172) , TBC1D1(Ser231) , TBC1D4(Ser704) and ACC(Ser221) ) or higher (GS(2+2a) ). Exercise-induced glycogen degradation in type I vs. II fibres was similar (CON) or lower (INT). In conclusion, a differentiated response to exercise of metabolic signalling/effector proteins in human type I and II fibres was evident during interval exercise. This could be important for exercise type-specific adaptations, i.e. insulin sensitivity and mitochondrial density, and highlights the potential for new discoveries when investigating fibre type-specific signalling.
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Affiliation(s)
- Dorte E Kristensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
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Abstract
Accumulation of triacylglycerols within the cytoplasm of hepatocytes to the degree that lipid droplets are visible microscopically is called liver steatosis. Most commonly, it occurs when there is an imbalance between the delivery or synthesis of fatty acids in the liver and their disposal through oxidative pathways or secretion into the blood as a component of triacylglycerols in very low density lipoprotein. This disorder is called nonalcoholic fatty liver disease (NAFLD) in the absence of alcoholic abuse and viral hepatitis, and it is often associated with insulin resistance, obesity and type 2 diabetes. Also, liver steatosis can be induced by many other causes including excessive alcohol consumption, infection with genotype 3 hepatitis C virus and certain medications. Whereas hepatic triacylglycerol accumulation was once considered the ultimate effector of hepatic lipotoxicity, triacylglycerols per se are quite inert and do not induce insulin resistance or cellular injury. Rather, lipotoxic injury in the liver appears to be mediated by the global ongoing fatty acid enrichment in the liver, paralleling the development of insulin resistance. A considerable number of fatty acid metabolites may be responsible for hepatic lipotoxicity and liver injury. Additional key contributors include hepatic cytosolic lipases and the "lipophagy" of lipid droplets, as sources of hepatic fatty acids. The specific origin of the lipids, mainly triacylglycerols, accumulating in liver has been unraveled by recent kinetic studies, and identifying the origin of the accumulated triacylglycerols in the liver of patients with NAFLD may direct the prevention and treatment of this condition.
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Affiliation(s)
- David Q-H Wang
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, Missouri
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Abbott MJ, Turcotte LP. AMPK-α2 is involved in exercise training-induced adaptations in insulin-stimulated metabolism in skeletal muscle following high-fat diet. J Appl Physiol (1985) 2014; 117:869-79. [DOI: 10.1152/japplphysiol.01380.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
AMP-activated protein kinase (AMPK) has been studied extensively and postulated to be a target for the treatment and/or prevention of metabolic disorders such as insulin resistance. Exercise training has been deemed a beneficial treatment for obesity and insulin resistance. Furthermore, exercise is a feasible method to combat high-fat diet (HFD)-induced alterations in insulin sensitivity. The purpose of this study was to determine whether AMPK-α2 activity is required to gain beneficial effects of exercise training with high-fat feeding. Wild-type (WT) and AMPK-α2 dominant-negative (DN) male mice were fed standard diet (SD), underwent voluntary wheel running (TR), fed HFD, or trained with HFD (TR + HFD). By week 6, TR, irrespective of genotype, decreased blood glucose and increased citrate synthase activity in both diet groups and decreased insulin levels in HFD groups. Hindlimb perfusions were performed, and, in WT mice with SD, TR increased insulin-mediated palmitate uptake (76.7%) and oxidation (>2-fold). These training-induced changes were not observed in the DN mice. With HFD, TR decreased palmitate oxidation (61–64%) in both WT and DN and increased palmitate uptake (112%) in the WT with no effects on palmitate uptake in the DN. With SD, TR increased ERK1/2 and JNK1/2 phosphorylation, regardless of genotype. With HFD, TR reduced JNK1/2 phosphorylation, regardless of genotype, carnitine palmitoyltransferase 1 expression in WT, and CD36 expression in both DN and WT. These data suggest that low AMPK-α2 signaling disrupts, in part, the exercise training-induced adaptations in insulin-stimulated metabolism in skeletal muscle following HFD.
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Affiliation(s)
- Marcia J. Abbott
- Department of Biological Sciences, Human and Evolutionary Biology Section, Dana and David Dornsife College of Arts, Letters, and Sciences, University of Southern California, Los Angeles, California; and
- Crean College of Health and Behavioral Sciences, Chapman University, Orange, California
| | - Lorraine P. Turcotte
- Department of Biological Sciences, Human and Evolutionary Biology Section, Dana and David Dornsife College of Arts, Letters, and Sciences, University of Southern California, Los Angeles, California; and
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Neels JG, Grimaldi PA. Physiological functions of peroxisome proliferator-activated receptor β. Physiol Rev 2014; 94:795-858. [PMID: 24987006 DOI: 10.1152/physrev.00027.2013] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The peroxisome proliferator-activated receptors, PPARα, PPARβ, and PPARγ, are a family of transcription factors activated by a diversity of molecules including fatty acids and fatty acid metabolites. PPARs regulate the transcription of a large variety of genes implicated in metabolism, inflammation, proliferation, and differentiation in different cell types. These transcriptional regulations involve both direct transactivation and interaction with other transcriptional regulatory pathways. The functions of PPARα and PPARγ have been extensively documented mainly because these isoforms are activated by molecules clinically used as hypolipidemic and antidiabetic compounds. The physiological functions of PPARβ remained for a while less investigated, but the finding that specific synthetic agonists exert beneficial actions in obese subjects uplifted the studies aimed to elucidate the roles of this PPAR isoform. Intensive work based on pharmacological and genetic approaches and on the use of both in vitro and in vivo models has considerably improved our knowledge on the physiological roles of PPARβ in various cell types. This review will summarize the accumulated evidence for the implication of PPARβ in the regulation of development, metabolism, and inflammation in several tissues, including skeletal muscle, heart, skin, and intestine. Some of these findings indicate that pharmacological activation of PPARβ could be envisioned as a therapeutic option for the correction of metabolic disorders and a variety of inflammatory conditions. However, other experimental data suggesting that activation of PPARβ could result in serious adverse effects, such as carcinogenesis and psoriasis, raise concerns about the clinical use of potent PPARβ agonists.
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Affiliation(s)
- Jaap G Neels
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
| | - Paul A Grimaldi
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
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Hooper PL, Balogh G, Rivas E, Kavanagh K, Vigh L. The importance of the cellular stress response in the pathogenesis and treatment of type 2 diabetes. Cell Stress Chaperones 2014; 19:447-64. [PMID: 24523032 PMCID: PMC4041942 DOI: 10.1007/s12192-014-0493-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 12/24/2013] [Accepted: 01/02/2014] [Indexed: 01/06/2023] Open
Abstract
Organisms have evolved to survive rigorous environments and are not prepared to thrive in a world of caloric excess and sedentary behavior. A realization that physical exercise (or lack of it) plays a pivotal role in both the pathogenesis and therapy of type 2 diabetes mellitus (t2DM) has led to the provocative concept of therapeutic exercise mimetics. A decade ago, we attempted to simulate the beneficial effects of exercise by treating t2DM patients with 3 weeks of daily hyperthermia, induced by hot tub immersion. The short-term intervention had remarkable success, with a 1 % drop in HbA1, a trend toward weight loss, and improvement in diabetic neuropathic symptoms. An explanation for the beneficial effects of exercise and hyperthermia centers upon their ability to induce the cellular stress response (the heat shock response) and restore cellular homeostasis. Impaired stress response precedes major metabolic defects associated with t2DM and may be a near seminal event in the pathogenesis of the disease, tipping the balance from health into disease. Heat shock protein inducers share metabolic pathways associated with exercise with activation of AMPK, PGC1-a, and sirtuins. Diabetic therapies that induce the stress response, whether via heat, bioactive compounds, or genetic manipulation, improve or prevent all of the morbidities and comorbidities associated with the disease. The agents reduce insulin resistance, inflammatory cytokines, visceral adiposity, and body weight while increasing mitochondrial activity, normalizing membrane structure and lipid composition, and preserving organ function. Therapies restoring the stress response can re-tip the balance from disease into health and address the multifaceted defects associated with the disease.
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Affiliation(s)
- Philip L. Hooper
- />Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO USA
| | - Gabor Balogh
- />Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Eric Rivas
- />Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas and University of Texas Southwestern Medical Center, Dallas, TX USA
- />Department of Kinesiology, Texas Woman’s University, Denton, TX USA
| | - Kylie Kavanagh
- />Department of Pathology, Wake Forest School of Medicine, Winston–Salem, NC USA
| | - Laszlo Vigh
- />Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
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Goyaram V, Kohn TA, Ojuka EO. Suppression of the GLUT4 adaptive response to exercise in fructose-fed rats. Am J Physiol Endocrinol Metab 2014; 306:E275-83. [PMID: 24326422 PMCID: PMC3920014 DOI: 10.1152/ajpendo.00342.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Exercise-induced increase in skeletal muscle GLUT4 expression is associated with hyperacetylation of histone H3 within a 350-bp DNA region surrounding the myocyte enhancer factor 2 (MEF2) element on the Glut4 promoter and increased binding of MEF2A. Previous studies have hypothesized that the increase in MEF2A binding is a result of improved accessibility of this DNA segment. Here, we investigated the impact of fructose consumption on exercise-induced GLUT4 adaptive response and directly measured the accessibility of the above segment to nucleases. Male Wistar rats (n = 30) were fed standard chow or chow + 10% fructose or maltodextrin drinks ad libitum for 13 days. In the last 6 days five animals per group performed 3 × 17-min bouts of intermittent swimming daily and five remained untrained. Triceps muscles were harvested and used to measure 1) GLUT4, pAMPK, and HDAC5 contents by Western blot, 2) accessibility of the DNA segment from intact nuclei using nuclease accessibility assays, 3) acetylation level of histone H3 and bound MEF2A by ChIP assays, and 4) glycogen content. Swim training increased GLUT4 content by ∼66% (P < 0.05) but fructose and maltodextrin feeding suppressed the adaptation. Accessibility of the DNA region to MNase and DNase I was significantly increased by swimming (∼2.75- and 5.75-fold, respectively) but was also suppressed in trained rats that consumed fructose or maltodextrin. Histone H3 acetylation and MEF2A binding paralleled the accessibility pattern. These findings indicate that both fructose and maltodextrin modulate the GLUT4 adaptive response to exercise by mechanisms involving chromatin remodeling at the Glut4 promoter.
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Affiliation(s)
- Veeraj Goyaram
- University of Capetown/Medical Research Center, Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
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Mortensen B, Friedrichsen M, Andersen NR, Alibegovic AC, Højbjerre L, Sonne MP, Stallknecht B, Dela F, Wojtaszewski JFP, Vaag A. Physical inactivity affects skeletal muscle insulin signaling in a birth weight-dependent manner. J Diabetes Complications 2014; 28:71-8. [PMID: 24120282 DOI: 10.1016/j.jdiacomp.2013.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 10/26/2022]
Abstract
AIMS We investigated whether physical inactivity could unmask defects in insulin and AMPK signaling in low birth weight (LBW) subjects. METHODS Twenty LBW and 20 normal birth weight (NBW) subjects were investigated using the euglycemic-hyperinsulinemic clamp with excision of skeletal muscle biopsies pre and post 9days of bed rest. Employing Western blotting, we investigated skeletal muscle Akt, AS160, GLUT4, and AMPK signaling. RESULTS Peripheral insulin action was similar in the two groups and was decreased to the same extent post bed rest. Insulin and AMPK signaling was unaffected by bed rest in NBW individuals. LBW subjects showed decreased insulin-stimulated Akt phosphorylation and increased AMPK α1 and γ3 protein expression post bed rest. Insulin response of AS160 phosphorylation was lower in LBW subjects both pre and post bed rest. CONCLUSIONS Bed rest-induced insulin resistance is not explained by impaired muscle insulin or AMPK signaling in subjects with or without LBW. Lower muscle insulin signaling in LBW subjects post bed rest despite similar degree of insulin resistance as seen in controls may to some extent support the idea that LBW subjects are at higher risk of developing type 2 diabetes when being physically inactive.
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Affiliation(s)
- Brynjulf Mortensen
- Steno Diabetes Center, Gentofte, Denmark; Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen.
| | - Martin Friedrichsen
- Steno Diabetes Center, Gentofte, Denmark; Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen
| | - Nicoline R Andersen
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen
| | | | - Lise Højbjerre
- Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen
| | - Mette P Sonne
- Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen
| | | | - Flemming Dela
- Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen
| | - Jørgen F P Wojtaszewski
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen
| | - Allan Vaag
- Steno Diabetes Center, Gentofte, Denmark; Rigshospitalet, Department of Endocrinology, Denmark
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Hoppeler H, Baum O, Lurman G, Mueller M. Molecular mechanisms of muscle plasticity with exercise. Compr Physiol 2013; 1:1383-412. [PMID: 23733647 DOI: 10.1002/cphy.c100042] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The skeletal muscle phenotype is subject to considerable malleability depending on use. Low-intensity endurance type exercise leads to qualitative changes of muscle tissue characterized mainly by an increase in structures supporting oxygen delivery and consumption. High-load strength-type exercise leads to growth of muscle fibers dominated by an increase in contractile proteins. In low-intensity exercise, stress-induced signaling leads to transcriptional upregulation of a multitude of genes with Ca(2+) signaling and the energy status of the muscle cells sensed through AMPK being major input determinants. Several parallel signaling pathways converge on the transcriptional co-activator PGC-1α, perceived as being the coordinator of much of the transcriptional and posttranscriptional processes. High-load training is dominated by a translational upregulation controlled by mTOR mainly influenced by an insulin/growth factor-dependent signaling cascade as well as mechanical and nutritional cues. Exercise-induced muscle growth is further supported by DNA recruitment through activation and incorporation of satellite cells. Crucial nodes of strength and endurance exercise signaling networks are shared making these training modes interdependent. Robustness of exercise-related signaling is the consequence of signaling being multiple parallel with feed-back and feed-forward control over single and multiple signaling levels. We currently have a good descriptive understanding of the molecular mechanisms controlling muscle phenotypic plasticity. We lack understanding of the precise interactions among partners of signaling networks and accordingly models to predict signaling outcome of entire networks. A major current challenge is to verify and apply available knowledge gained in model systems to predict human phenotypic plasticity.
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Affiliation(s)
- Hans Hoppeler
- Institute of Anatomy, University of Bern, Bern, Switzerland.
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Roberts CK, Hevener AL, Barnard RJ. Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training. Compr Physiol 2013; 3:1-58. [PMID: 23720280 DOI: 10.1002/cphy.c110062] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Metabolic syndrome (MS) is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Regardless of the true definition, based on current population estimates, nearly 100 million have MS. It is often characterized by insulin resistance, which some have suggested is a major underpinning link between physical inactivity and MS. The purpose of this review is to: (i) provide an overview of the history, causes and clinical aspects of MS, (ii) review the molecular mechanisms of insulin action and the causes of insulin resistance, and (iii) discuss the epidemiological and intervention data on the effects of exercise on MS and insulin sensitivity.
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Affiliation(s)
- Christian K Roberts
- Exercise and Metabolic Disease Research Laboratory, Translational Sciences Section, School of Nursing, University of California at Los Angeles, Los Angeles, California, USA.
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Kostovski E, Boon H, Hjeltnes N, Lundell LS, Ahlsén M, Chibalin AV, Krook A, Iversen PO, Widegren U. Altered content of AMP-activated protein kinase isoforms in skeletal muscle from spinal cord injured subjects. Am J Physiol Endocrinol Metab 2013; 305:E1071-80. [PMID: 24022865 DOI: 10.1152/ajpendo.00132.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
AMP-activated protein kinase (AMPK) is a pivotal regulator of energy homeostasis. Although downstream targets of AMPK are widely characterized, the physiological factors governing isoform expression of this protein kinase are largely unknown. Nerve/contractile activity has a major impact on the metabolic phenotype of skeletal muscle, therefore likely to influence AMPK isoform expression. Spinal cord injury represents an extreme form of physical inactivity, with concomitant changes in skeletal muscle metabolism. We assessed the influence of longstanding and recent spinal cord injury on protein abundance of AMPK isoforms in human skeletal muscle. We also determined muscle fiber type as a marker of glycolytic or oxidative metabolism. In subjects with longstanding complete injury, protein abundance of the AMPKγ3 subunit, as well as myosin heavy chain (MHC) IIa and IIx, were increased, whereas abundance of the AMPKγ1 subunit and MHC I were decreased. Similarly, abundance of AMPKγ3 and MHC IIa proteins were increased, whereas AMPKα2, -β1, and -γ1 subunits and MHC I abundance was decreased during the first year following injury, reflecting a more glycolytic phenotype of the skeletal muscle. However, in incomplete cervical lesions, partial recovery of muscle function attenuated the changes in the isoform profile of AMPK and MHC. Furthermore, exercise training (electrically stimulated leg cycling) partly normalized mRNA expression of AMPK isoforms. Thus, physical activity affects the relative expression of AMPK isoforms. In conclusion, skeletal muscle abundance of AMPK isoforms is related to physical activity and/or muscle fiber type. Thus, physical/neuromuscular activity is an important determinant of isoform abundance of AMPK and MCH. This further underscores the need for physical activity as part of a treatment regimen after spinal cord injury to maintain skeletal muscle metabolism.
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Affiliation(s)
- Emil Kostovski
- Section for Spinal Cord Injury, Sunnaas Rehabilitation Hospital, Nesoddtangen, Norway
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Wu J, Puppala D, Feng X, Monetti M, Lapworth AL, Geoghegan KF. Chemoproteomic analysis of intertissue and interspecies isoform diversity of AMP-activated protein kinase (AMPK). J Biol Chem 2013; 288:35904-12. [PMID: 24187138 DOI: 10.1074/jbc.m113.508747] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that senses and governs changes in the cellular energy balance represented by concentrations of AMP, ADP, and ATP. Each of its three chains (α, β, and γ) exists as either two or three subtypes, theoretically allowing up to 12 different forms of the complete enzyme. Tissue specificity in the distribution of AMPK subtypes is believed to underpin a range of biological functions for AMPK, a central regulator of metabolic function and response. It is of particular interest for drug discovery purposes to compare AMPK isoforms that are most prevalent in human liver and muscle with isoforms present in key preclinical species. To complement immunocapture/immunodetection methods, which for AMPK are challenged by sequence similarities and difficulties of obtaining accurate relative quantitation, AMPK was captured from lysates of a range of cells and tissues using the ActivX ATP probe. This chemical probe covalently attaches desthiobiotin to one or more conserved lysyl residues in the ATP-binding sites of protein kinases, including AMPK, while also labeling a wide range of ATP-utilizing proteins. Affinity-based recovery of labeled proteins followed by gel-based fractionation of the captured sample was followed by proteomic characterization of AMPK polypeptides. In agreement with transcript-based analysis and previous indications from immunodetection, the results indicated that the predominant AMPK heterotrimer in human liver is α1β2γ1 but that dog and rat livers mainly contain the α1β1γ1 and α2β1γ1 forms, respectively. Differences were not detected between the AMPK profiles of normal and diabetic human liver tissues.
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Affiliation(s)
- Jiang Wu
- From Pfizer Worldwide Research, Groton, Connecticut 06340 and
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Golden SH, Kim C, Barrett-Connor E, Nan B, Kong S, Goldberg R. The association of elective hormone therapy with changes in lipids among glucose intolerant postmenopausal women in the diabetes prevention program. Metabolism 2013; 62:1313-22. [PMID: 23660512 PMCID: PMC3755098 DOI: 10.1016/j.metabol.2013.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/24/2013] [Accepted: 04/03/2013] [Indexed: 01/31/2023]
Abstract
OBJECTIVE It is unclear how lipids change in response to lifestyle modification or metformin among postmenopausal glucose intolerant women using and not using hormone therapy (HT). We examined the one-year changes in lipids among postmenopausal, prediabetic women in the Diabetes Prevention Program (DPP), and whether changes were mediated by sex hormones. MATERIALS/METHODS We performed a secondary analysis of a randomized controlled trial of 342 women who used HT at baseline and year 1 and 382 women who did not use HT at either time point. Interventions included intensive lifestyle (ILS) with goals of weight reduction of at least 7% of initial weight and 150 minutes per week of moderate intensity exercise, or metformin or placebo administered 850 mg up to twice a day. Women were not randomized to HT. Main outcome measures were changes between baseline and study year 1 in low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides. RESULTS Compared to placebo, both ILS and metformin significantly reduced LDL-C and raised HDL-C among HT users, changes partially explained by change in estradiol and testosterone but independent of changes in waist circumference and 1/fasting insulin. In contrast, DPP interventions had no effect on LDL-C and HDL-C among non-HT users. ILS significantly lowered triglycerides among non-users but did not significantly change triglycerides among HT users. Metformin did not significantly change triglycerides among non-users but increased triglycerides among HT users. CONCLUSIONS The beneficial effects of ILS and metformin on lowering LDL-C and raising HDL-C differ depending upon concurrent HT use.
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Brandauer J, Vienberg SG, Andersen MA, Ringholm S, Risis S, Larsen PS, Kristensen JM, Frøsig C, Leick L, Fentz J, Jørgensen S, Kiens B, Wojtaszewski JFP, Richter EA, Zierath JR, Goodyear LJ, Pilegaard H, Treebak JT. AMP-activated protein kinase regulates nicotinamide phosphoribosyl transferase expression in skeletal muscle. J Physiol 2013; 591:5207-20. [PMID: 23918774 DOI: 10.1113/jphysiol.2013.259515] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Deacetylases such as sirtuins (SIRTs) convert NAD to nicotinamide (NAM). Nicotinamide phosphoribosyl transferase (Nampt) is the rate-limiting enzyme in the NAD salvage pathway responsible for converting NAM to NAD to maintain cellular redox state. Activation of AMP-activated protein kinase (AMPK) increases SIRT activity by elevating NAD levels. As NAM directly inhibits SIRTs, increased Nampt activation or expression could be a metabolic stress response. Evidence suggests that AMPK regulates Nampt mRNA content, but whether repeated AMPK activation is necessary for increasing Nampt protein levels is unknown. To this end, we assessed whether exercise training- or 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR)-mediated increases in skeletal muscle Nampt abundance are AMPK dependent. One-legged knee-extensor exercise training in humans increased Nampt protein by 16% (P < 0.05) in the trained, but not the untrained leg. Moreover, increases in Nampt mRNA following acute exercise or AICAR treatment (P < 0.05 for both) were maintained in mouse skeletal muscle lacking a functional AMPK α2 subunit. Nampt protein was reduced in skeletal muscle of sedentary AMPK α2 kinase dead (KD), but 6.5 weeks of endurance exercise training increased skeletal muscle Nampt protein to a similar extent in both wild-type (WT) (24%) and AMPK α2 KD (18%) mice. In contrast, 4 weeks of daily AICAR treatment increased Nampt protein in skeletal muscle in WT mice (27%), but this effect did not occur in AMPK α2 KD mice. In conclusion, functional α2-containing AMPK heterotrimers are required for elevation of skeletal muscle Nampt protein, but not mRNA induction. These findings suggest AMPK plays a post-translational role in the regulation of skeletal muscle Nampt protein abundance, and further indicate that the regulation of cellular energy charge and nutrient sensing is mechanistically related.
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Affiliation(s)
- Josef Brandauer
- J. T. Treebak: University of Copenhagen, NNF Center for Basic Metabolic Research, Blegdamsvej 3b, 6.6.28, Copenhagen DK2200, Denmark.
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Potential mechanisms linking atherosclerosis and increased cardiovascular risk in COPD: focus on Sirtuins. Int J Mol Sci 2013; 14:12696-713. [PMID: 23774840 PMCID: PMC3709808 DOI: 10.3390/ijms140612696] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 05/11/2013] [Accepted: 06/05/2013] [Indexed: 11/17/2022] Open
Abstract
The development of atherosclerosis is a multi-step process, at least in part controlled by the vascular endothelium function. Observations in humans and experimental models of atherosclerosis have identified monocyte recruitment as an early event in atherogenesis. Chronic inflammation is associated with ageing and its related diseases (e.g., atherosclerosis and chronic obstructive pulmonary disease). Recently it has been discovered that Sirtuins (NAD+-dependent deacetylases) represent a pivotal regulator of longevity and health. They appear to have a prominent role in vascular biology and regulate aspects of age-dependent atherosclerosis. Many studies demonstrate that SIRT1 exhibits anti-inflammatory properties in vitro (e.g., fatty acid-induced inflammation), in vivo (e.g., atherosclerosis, sustainment of normal immune function in knock-out mice) and in clinical studies (e.g., patients with chronic obstructive pulmonary disease). Because of a significant reduction of SIRT1 in rodent lungs exposed to cigarette smoke and in lungs of patients with chronic obstructive pulmonary disease (COPD), activation of SIRT1 may be a potential target for chronic obstructive pulmonary disease therapy. We review the inflammatory mechanisms involved in COPD-CVD coexistence and the potential role of SIRT1 in the regulation of these systems.
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Mortensen B, Hingst JR, Frederiksen N, Hansen RWW, Christiansen CS, Iversen N, Friedrichsen M, Birk JB, Pilegaard H, Hellsten Y, Vaag A, Wojtaszewski JFP. Effect of birth weight and 12 weeks of exercise training on exercise-induced AMPK signaling in human skeletal muscle. Am J Physiol Endocrinol Metab 2013; 304:E1379-90. [PMID: 23612997 DOI: 10.1152/ajpendo.00295.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Subjects with a low birth weight (LBW) display increased risk of developing type 2 diabetes (T2D). We hypothesized that this is associated with defects in muscle adaptations following acute and regular physical activity, evident by impairments in the exercise-induced activation of AMPK signaling. We investigated 21 LBW and 21 normal birth weight (NBW) subjects during 1 h of acute exercise performed at the same relative workload before and after 12 wk of exercise training. Multiple skeletal muscle biopsies were obtained before and after exercise. Protein levels and phosphorylation status were determined by Western blotting. AMPK activities were measured using activity assays. Protein levels of AMPKα1 and -γ1 were significantly increased, whereas AMPKγ3 levels decreased with training independently of group. The LBW group had higher exercise-induced AMPK Thr(172) phosphorylation before training and higher exercise-induced ACC2 Ser(221) phosphorylation both before and after training compared with NBW. Despite exercise being performed at the same relative intensity (65% of Vo2peak), the acute exercise response on AMPK Thr(172), ACC2 Ser(221), AMPKα2β2γ1, and AMPKα2β2γ3 activities, GS activity, and adenine nucleotides as well as hexokinase II mRNA levels were all reduced after exercise training. Increased exercise-induced muscle AMPK activation and ACC2 Ser(221) phosphorylation in LBW subjects may indicate a more sensitive AMPK system in this population. Long-term exercise training may reduce the need for AMPK to control energy turnover during exercise. Thus, the remaining γ3-associated AMPK activation by acute exercise after exercise training might be sufficient to maintain cellular energy balance.
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Sriwijitkamol A, Musi N. Advances in the development of AMPK-activating compounds. Expert Opin Drug Discov 2013; 3:1167-76. [PMID: 23489075 DOI: 10.1517/17460441.3.10.1167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) is an energy sensing enzyme that controls glucose and lipid metabolism. OBJECTIVE This review summarizes the present data on AMPK as a pharmacologic target for the treatment of metabolic disorders. METHODS The mechanisms governing AMPK activity and how this enzyme controls different metabolic pathways are reviewed briefly, and details about the effect that AMPK activators have on glucose metabolism are provided. CONCLUSION Evidence obtained using the AMPK-activating compound 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) suggests that AMPK promotes glucose transport into skeletal muscles and that this enzyme inhibits hepatic glucose production. AICAR also induces fatty acid oxidation in muscle and inhibits cholesterol synthesis in the liver. The metabolic effects of AICAR on glucose and lipid metabolism indicate that AMPK may be a good pharmacologic target for the treatment of type 2 diabetes and hypercholesterolemia. Novel AMPK-specific compounds are allowing researchers to examine whether this enzyme is a useful pharmacologic target for the treatment of human disease and whether chronic activation of AMPK will be safe.
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Affiliation(s)
- Apiradee Sriwijitkamol
- University of Texas Health Science Center at San Antonio, Diabetes Division, San Antonio, Texas, USA
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Friedrichsen M, Mortensen B, Pehmøller C, Birk JB, Wojtaszewski JFP. Exercise-induced AMPK activity in skeletal muscle: role in glucose uptake and insulin sensitivity. Mol Cell Endocrinol 2013; 366:204-14. [PMID: 22796442 DOI: 10.1016/j.mce.2012.06.013] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
Abstract
The energy/fuel sensor 5'-AMP-activated protein kinase (AMPK) is viewed as a master regulator of cellular energy balance due to its many roles in glucose, lipid, and protein metabolism. In this review we focus on the regulation of AMPK activity in skeletal muscle and its involvement in glucose metabolism, including glucose transport and glycogen synthesis. In addition, we discuss the plausible interplay between AMPK and insulin signaling regulating these processes.
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Affiliation(s)
- Martin Friedrichsen
- Molecular Physiology Group, The August Krogh Centre, Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
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Abstract
AMPK is an evolutionary conserved sensor of cellular energy status that is activated during exercise. Pharmacological activation of AMPK promotes glucose uptake, fatty acid oxidation, mitochondrial biogenesis, and insulin sensitivity; processes that are reduced in obesity and contribute to the development of insulin resistance. AMPK deficient mouse models have been used to provide direct genetic evidence either supporting or refuting a role for AMPK in regulating these processes. Exercise promotes glucose uptake by an insulin dependent mechanism involving AMPK. Exercise is important for improving insulin sensitivity; however, it is not known if AMPK is required for these improvements. Understanding how these metabolic processes are regulated is important for the development of new strategies that target obesity-induced insulin resistance. This review will discuss the involvement of AMPK in regulating skeletal muscle metabolism (glucose uptake, glycogen synthesis, and insulin sensitivity).
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Affiliation(s)
- Hayley M. O'Neill
- Protein Chemistry and Metabolism Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia
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Høeg LD, Sjøberg KA, Lundsgaard AM, Jordy AB, Hiscock N, Wojtaszewski JFP, Richter EA, Kiens B. Adiponectin concentration is associated with muscle insulin sensitivity, AMPK phosphorylation, and ceramide content in skeletal muscles of men but not women. J Appl Physiol (1985) 2013; 114:592-601. [PMID: 23305978 DOI: 10.1152/japplphysiol.01046.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Adiponectin is an adipokine that regulates metabolism and increases insulin sensitivity. Mechanisms behind this insulin-sensitizing effect have been investigated in rodents, but little is known in humans, especially in skeletal muscle. Women have higher serum concentrations of adiponectin than men and are generally more insulin sensitive in skeletal muscle than men. We show here that large differences exist between men and women with regard to apparent adiponectin regulation of insulin-stimulated glucose uptake in skeletal muscle. Serum adiponectin was significantly associated with leg glucose uptake in healthy, young, lean men, but the association was absent in women. In addition, serum adiponectin was significantly associated with AMP-activated protein kinase (AMPK) phosphorylation in skeletal muscles of men but not in women. Serum adiponectin was also significantly, negatively associated with skeletal muscle ceramide content in men only, and interestingly, ceramide content was negatively associated with adiponectin receptor 1 (AdipoR1) expression in skeletal muscles of men. Women had lower AdipoR1 expression in skeletal muscle and a lower percentage of glycolytic adiponectin-sensitive type 2 muscle fibers than men. These associations suggest that the insulin-sensitizing effect of adiponectin on human male skeletal muscles may be mediated via AdipoR1 to activation of AMPK, leading to lowering of ceramide content. The lower skeletal muscle AdipoR1 protein expression and lower expression of adiponectin-sensitive type 2 muscle fibers in women than in men may explain the apparent lesser sensitivity to adiponectin in women.
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Affiliation(s)
- Louise D Høeg
- The August Krogh Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
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