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Deshmukh AS, Steenberg DE, Hostrup M, Birk JB, Larsen JK, Santos A, Kjøbsted R, Hingst JR, Schéele CC, Murgia M, Kiens B, Richter EA, Mann M, Wojtaszewski JFP. Deep muscle-proteomic analysis of freeze-dried human muscle biopsies reveals fiber type-specific adaptations to exercise training. Nat Commun 2021; 12:304. [PMID: 33436631 PMCID: PMC7803955 DOI: 10.1038/s41467-020-20556-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 12/01/2020] [Indexed: 01/29/2023] Open
Abstract
Skeletal muscle conveys several of the health-promoting effects of exercise; yet the underlying mechanisms are not fully elucidated. Studying skeletal muscle is challenging due to its different fiber types and the presence of non-muscle cells. This can be circumvented by isolation of single muscle fibers. Here, we develop a workflow enabling proteomics analysis of pools of isolated muscle fibers from freeze-dried human muscle biopsies. We identify more than 4000 proteins in slow- and fast-twitch muscle fibers. Exercise training alters expression of 237 and 172 proteins in slow- and fast-twitch muscle fibers, respectively. Interestingly, expression levels of secreted proteins and proteins involved in transcription, mitochondrial metabolism, Ca2+ signaling, and fat and glucose metabolism adapts to training in a fiber type-specific manner. Our data provide a resource to elucidate molecular mechanisms underlying muscle function and health, and our workflow allows fiber type-specific proteomic analyses of snap-frozen non-embedded human muscle biopsies.
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Affiliation(s)
- A S Deshmukh
- The Novo Nordisk Foundation Center for Protein Research, Clinical Proteomics, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- The Novo Nordisk Foundation Center for Basic Metablic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - D E Steenberg
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - M Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - J B Birk
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - J K Larsen
- The Novo Nordisk Foundation Center for Basic Metablic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - A Santos
- The Novo Nordisk Foundation Center for Protein Research, Clinical Proteomics, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - R Kjøbsted
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - J R Hingst
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - C C Schéele
- The Novo Nordisk Foundation Center for Basic Metablic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- The Centre of Inflammation and Metabolism and Centre for Physical Activity Research Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - M Murgia
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - B Kiens
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - E A Richter
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - M Mann
- The Novo Nordisk Foundation Center for Protein Research, Clinical Proteomics, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - J F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
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Maile CA, Hingst JR, Mahalingan KK, O'Reilly AO, Cleasby ME, Mickelson JR, McCue ME, Anderson SM, Hurley TD, Wojtaszewski JFP, Piercy RJ. A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase. Biochim Biophys Acta Gen Subj 2016; 1861:3388-3398. [PMID: 27592162 DOI: 10.1016/j.bbagen.2016.08.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/15/2016] [Accepted: 08/30/2016] [Indexed: 01/16/2023]
Abstract
BACKGROUND Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. METHODS Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. RESULTS PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower Km for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation. CONCLUSIONS Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state. GENERAL SIGNIFICANCE This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.
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Affiliation(s)
- C A Maile
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - J R Hingst
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - K K Mahalingan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - A O O'Reilly
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - M E Cleasby
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - J R Mickelson
- Veterinary Biomedical Sciences Department, University of Minnesota, St. Paul, MN, USA
| | - M E McCue
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - S M Anderson
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - T D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - J F P Wojtaszewski
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - R J Piercy
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.
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Grinder-Hansen L, Ribel-Madsen R, Wojtaszewski JFP, Poulsen P, Grunnet LG, Vaag A. A common variation of the PTEN gene is associated with peripheral insulin resistance. Diabetes Metab 2016; 42:280-4. [PMID: 27068875 DOI: 10.1016/j.diabet.2016.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/02/2016] [Accepted: 03/12/2016] [Indexed: 12/13/2022]
Abstract
AIM Phosphatase and tensin homologue (PTEN) reduces insulin sensitivity by inhibiting the phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homologue (Akt) pathway. This study investigated how a common single nucleotide polymorphism near PTEN, previously associated with fasting levels of plasma insulin and glucose, influences in vivo glucose metabolism and insulin signalling. The primary outcome measure was the gene variant's association with peripheral glucose disposal rate and, secondarily, whether this association was explained by altered activities of PTEN targets PI3K and Akt. METHODS A total of 183 normoglycaemic Danes, including 158 twins and 25 singletons, were genotyped for PTEN rs11202614, which is in complete linkage disequilibrium with rs2142136 and rs10788575, which have also been reported in association with glycaemic traits and type 2 diabetes (T2D). Hepatic and peripheral insulin sensitivity was measured using tracer and euglycaemic-hyperinsulinaemic clamp techniques; insulin secretion was assessed by intravenous glucose tolerance test; and muscle biopsies were taken during insulin infusion from 150 twins for measurement of PI3K and Akt activities. RESULTS The minor G allele of PTEN rs11202614 was associated with elevated fasting plasma insulin levels and a decreased peripheral glucose disposal rate, but not with the hepatic insulin resistance index or insulin secretion measured as the first-phase insulin response and disposition index. The single nucleotide polymorphism was not associated with either PI3K or Akt activities. CONCLUSION A common PTEN variation is associated with peripheral insulin resistance and subsequent risk of developing T2D. However, the association with insulin resistance is not explained by decreased proximal insulin signalling in skeletal muscle.
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Affiliation(s)
- L Grinder-Hansen
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark
| | - R Ribel-Madsen
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark; The Danish Diabetes Academy, Odense University Hospital, Sondre Boulevard 29, DK-5000 Odense, Denmark; Section of Metabolic Genetics, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Universitetsparken 1, DK-2100 Copenhagen O, Denmark.
| | - J F P Wojtaszewski
- Section of Molecular Physiology, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen O, Denmark
| | - P Poulsen
- Novo Nordisk A/S, Vandtårnsvej 108, DK-2860 Soborg, Denmark
| | - L G Grunnet
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark
| | - A Vaag
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark
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Vigelsø A, Gram M, Dybboe R, Kuhlman AB, Prats C, Greenhaff PL, Constantin-Teodosiu D, Birk JB, Wojtaszewski JFP, Dela F, Helge JW. The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate-intensity exercise in human skeletal muscle. J Physiol 2016; 594:2339-58. [PMID: 26801521 DOI: 10.1113/jp271712] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/15/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during moderate-intensity exercise. Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two-legged dynamic knee-extensor moderate-intensity exercise, as well as changes in key proteins in muscle metabolism before and after exercise. Age and immobilization did not affect relative carbohydrate and fat utilization during exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during exercise. Using a combined whole-leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms. ABSTRACT Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate-intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two-legged isolated knee-extensor exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity and the protein content of adipose triglyceride lipase, acetyl-CoA carboxylase 2 and AMP-activated protein kinase (AMPK)γ3 were higher in young than in older men. Furthermore, adipose triglyceride lipase, plasma membrane-associated fatty acid binding protein and AMPKγ3 subunit protein contents were lower and IMTG was higher in the immobilized than the contralateral leg in young and older men. Thus, immobilization and age did not affect substrate choice (respiratory quotient) during moderate exercise, but the whole-leg and molecular differences in fatty acid mobilization could explain the age- and immobilization-induced IMTG accumulation.
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Affiliation(s)
- A Vigelsø
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - M Gram
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - R Dybboe
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.,Section of Molecular Physiology, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - A B Kuhlman
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - C Prats
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - P L Greenhaff
- MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, School of Life Sciences, The Medical School, University of Nottingham, Nottingham, UK
| | - D Constantin-Teodosiu
- MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, School of Life Sciences, The Medical School, University of Nottingham, Nottingham, UK
| | - J B Birk
- Section of Molecular Physiology, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - J F P Wojtaszewski
- Section of Molecular Physiology, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - F Dela
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - J W Helge
- XLAB, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Vendelbo MH, Møller AB, Treebak JT, Gormsen LC, Goodyear LJ, Wojtaszewski JFP, Jørgensen JOL, Møller N, Jessen N. Sustained AS160 and TBC1D1 phosphorylations in human skeletal muscle 30 min after a single bout of exercise. J Appl Physiol (1985) 2014; 117:289-96. [PMID: 24876356 DOI: 10.1152/japplphysiol.00044.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND phosphorylation of AS160 and TBC1D1 plays an important role for GLUT4 mobilization to the cell surface. The phosphorylation of AS160 and TBC1D1 in humans in response to acute exercise is not fully characterized. OBJECTIVE to study AS160 and TBC1D1 phosphorylation in human skeletal muscle after aerobic exercise followed by a hyperinsulinemic euglycemic clamp. DESIGN eight healthy men were studied on two occasions: 1) in the resting state and 2) in the hours after a 1-h bout of ergometer cycling. A hyperinsulinemic euglycemic clamp was initiated 240 min after exercise and in a time-matched nonexercised control condition. We obtained muscle biopsies 30 min after exercise and in a time-matched nonexercised control condition (t = 30) and after 30 min of insulin stimulation (t = 270) and investigated site-specific phosphorylation of AS160 and TBC1D1. RESULTS phosphorylation on AS160 and TBC1D1 was increased 30 min after the exercise bout, whereas phosphorylation of the putative upstream kinases, Akt and AMPK, was unchanged compared with resting control condition. Exercise augmented insulin-stimulated phosphorylation on AS160 at Ser(341) and Ser(704) 270 min after exercise. No additional exercise effects were observed on insulin-stimulated phosphorylation of Thr(642) and Ser(588) on AS160 or Ser(237) and Thr(596) on TBC1D1. CONCLUSIONS AS160 and TBC1D1 phosphorylations were evident 30 min after exercise without simultaneously increased Akt and AMPK phosphorylation. Unlike TBC1D1, insulin-stimulated site-specific AS160 phosphorylation is modified by prior exercise, but these sites do not include Thr(642) and Ser(588). Together, these data provide new insights into phosphorylation of key regulators of glucose transport in human skeletal muscle.
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Affiliation(s)
- M H Vendelbo
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Nuclear Medicine and PET center, Aarhus University Hospital, Aarhus, Denmark
| | - A B Møller
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; Research Laboratory for Biochemical Pathology, Aarhus University Hospital, Aarhus, Denmark
| | - J T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - L C Gormsen
- Department of Nuclear Medicine and PET center, Aarhus University Hospital, Aarhus, Denmark
| | - L J Goodyear
- Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - J F P Wojtaszewski
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, The August Krogh Centre, University of Copenhagen, Copenhagen, Denmark; and
| | - J O L Jørgensen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - N Møller
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - N Jessen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; Research Laboratory for Biochemical Pathology, Aarhus University Hospital, Aarhus, Denmark; Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark
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Larsen S, Kristensen JM, Stride N, Wojtaszewski JFP, Helge JW, Dela F. Skeletal muscle mitochondrial respiration in AMPKα2 kinase-dead mice. Acta Physiol (Oxf) 2012; 205:314-20. [PMID: 22192354 DOI: 10.1111/j.1748-1716.2011.02399.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 11/18/2011] [Accepted: 12/13/2011] [Indexed: 11/28/2022]
Abstract
AIM To study whether the phenotypical characteristics (exercise intolerance; reduced spontaneous activity) of the AMPKα2 kinase-dead (KD) mice can be explained by a reduced mitochondrial respiratory flux rates (JO(2) ) in skeletal muscle. Secondly, the effect of the maturation process on JO(2) was studied. METHODS In tibialis anterior (almost exclusively type 2 fibres) muscle from young (12-17 weeks, n = 7) and mature (25-27 weeks, n = 12) KD and wild-type (WT) (12-17 weeks, n = 9; 25-27 weeks, n = 11) littermates, JO(2) was quantified in permeabilized fibres ex vivo by respirometry, using a substrate-uncoupler-inhibitor-titration (SUIT) protocol: malate, octanoyl carnitine, ADP and glutamate (GMO(3) ), + succinate (GMOS(3) ), + uncoupler (U) and inhibitor (rotenone) of complex I respiration. Citrate synthase (CS) activity was measured as an index of mitochondrial content. RESULTS Citrate synthase activity was highest in young WT animals and lower in KD animals compared with age-matched WT. JO(2) per mg tissue was lower (P < 0.05) in KD animals (state GMOS(3) ). No uncoupling effect was seen in any of the animals. Normalized oxygen flux (JO(2) /CS) revealed a uniform pattern across the SUIT protocol with no effect of KD. However, JO(2) /CS was higher [GMO(3) , GMOS(3) , U and rotenone (only WT)] in the mature compared with the young mice - irrespective of the genotype (P < 0.05). CONCLUSION Exercise intolerance and reduced activity level seen in KD mice may be explained by reduced JO(2) in the maximally coupled respiratory state. Furthermore, an enhancement of oxidative phosphorylation capacity per mitochondrion is seen with the maturation process.
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Affiliation(s)
- S. Larsen
- Xlab - Center for Healthy Aging; Department of Biomedical Sciences; Faculty of Health Sciences; University of Copenhagen; Copenhagen; Denmark
| | - J. M. Kristensen
- Molecular Physiology Group; Department of Exercise and Sport Sciences; Faculty of Natural Sciences; University of Copenhagen; Copenhagen; Denmark
| | - N. Stride
- Xlab - Center for Healthy Aging; Department of Biomedical Sciences; Faculty of Health Sciences; University of Copenhagen; Copenhagen; Denmark
| | - J. F. P. Wojtaszewski
- Molecular Physiology Group; Department of Exercise and Sport Sciences; Faculty of Natural Sciences; University of Copenhagen; Copenhagen; Denmark
| | - J. W. Helge
- Xlab - Center for Healthy Aging; Department of Biomedical Sciences; Faculty of Health Sciences; University of Copenhagen; Copenhagen; Denmark
| | - F. Dela
- Xlab - Center for Healthy Aging; Department of Biomedical Sciences; Faculty of Health Sciences; University of Copenhagen; Copenhagen; Denmark
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Brandt C, Jakobsen AH, Adser H, Olesen J, Iversen N, Kristensen JM, Hojman P, Wojtaszewski JFP, Hidalgo J, Pilegaard H. IL-6 regulates exercise and training-induced adaptations in subcutaneous adipose tissue in mice. Acta Physiol (Oxf) 2012; 205:224-35. [PMID: 21991887 DOI: 10.1111/j.1748-1716.2011.02373.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AIM The aim of this study was to test the hypothesis that IL-6 regulates exercise-induced gene responses in subcutaneous adipose tissue in mice. METHODS Four-month-old male IL-6 whole body knockout (KO) mice and C57B wild-type (WT) mice performed 1 h of treadmill exercise, where subcutaneous adipose tissue (AT) was removed either immediately after, 4 h or 10 h after exercise as well as from mice not running acutely. Moreover, AT was sampled at resting conditions after 5 weeks of exercise training. RESULTS AT leptin mRNA decreased immediately after a single running exercise bout in both genotypes and returned to baseline within 10 h of recovery in IL-6 KO mice, but not WT mice. Leptin mRNA content decreased in WT and increased in IL-6 KO mice with training, but without significant alterations in leptin protein. Acute exercise induced a decrease in the AT TNFα mRNA content in WT, but not in IL-6-KO mice, while training lowered resting levels of TNFα mRNA in both genotypes. In addition, an exercise-induced decline in AT PPARγ mRNA content was absent in IL-6 KO mice and in line training increased PPARγ mRNA only in IL-6 KO mice. CONCLUSION The present findings indicate a role of IL-6 in regulating exercise- and training-induced leptin and PPARγ expression in adipose tissue. In addition, while IL-6 is required for TNF-α mRNA reduction in response to acute exercise, IL-6 does not appear to be mandatory for anti-inflammatory effects of exercise training in adipose tissue.
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Affiliation(s)
- C Brandt
- Centre of Inflammation and Metabolism, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
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Vind BF, Birk JB, Vienberg SG, Andersen B, Beck-Nielsen H, Wojtaszewski JFP, Højlund K. Hyperglycaemia normalises insulin action on glucose metabolism but not the impaired activation of AKT and glycogen synthase in the skeletal muscle of patients with type 2 diabetes. Diabetologia 2012; 55:1435-45. [PMID: 22322917 DOI: 10.1007/s00125-012-2482-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
Abstract
AIMS/HYPOTHESIS In type 2 diabetes, reduced insulin-stimulated glucose disposal, primarily glycogen synthesis, is associated with defective insulin activation of glycogen synthase (GS) in skeletal muscle. Hyperglycaemia may compensate for these defects, but to what extent it involves improved insulin signalling to glycogen synthesis remains to be clarified. METHODS Whole-body glucose metabolism was studied in 12 patients with type 2 diabetes, and 10 lean and 10 obese non-diabetic controls by means of indirect calorimetry and tracers during a euglycaemic-hyperinsulinaemic clamp. The diabetic patients underwent a second isoglycaemic-hyperinsulinaemic clamp maintaining fasting hyperglycaemia. Muscle biopsies from m. vastus lateralis were obtained before and after the clamp for examination of GS and relevant insulin signalling components. RESULTS During euglycaemia, insulin-stimulated glucose disposal, glucose oxidation and non-oxidative glucose metabolism were reduced in the diabetic group compared with both control groups (p < 0.05). This was associated with impaired insulin-stimulated GS and AKT2 activity, deficient dephosphorylation at GS sites 2 + 2a, and reduced Thr308 and Ser473 phosphorylation of AKT. When studied under hyperglycaemia, all variables of insulin-stimulated glucose metabolism were normalised compared with the weight-matched controls. However, insulin activation and dephosphorylation (site 2 + 2a) of GS as well as activation of AKT2 and phosphorylation at Thr308 and Ser473 remained impaired (p < 0.05). CONCLUSIONS/INTERPRETATIONS These data confirm that hyperglycaemia compensates for decreased whole-body glucose disposal in type 2 diabetes. In contrast to previous less well-controlled studies, we provide evidence that the compensatory effect of hyperglycaemia in patients with type 2 diabetes does not involve normalisation of insulin action on GS or upstream signalling in skeletal muscle.
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Affiliation(s)
- B F Vind
- Diabetes Research Centre, Department of Endocrinology, Odense University Hospital, DK-5000 Odense, Denmark
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9
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Vendelbo MH, Clasen BFF, Treebak JT, Møller L, Krusenstjerna-Hafstrøm T, Madsen M, Nielsen TS, Stødkilde-Jørgensen H, Pedersen SB, Jørgensen JOL, Goodyear LJ, Wojtaszewski JFP, Møller N, Jessen N. Insulin resistance after a 72-h fast is associated with impaired AS160 phosphorylation and accumulation of lipid and glycogen in human skeletal muscle. Am J Physiol Endocrinol Metab 2012; 302:E190-200. [PMID: 22028408 PMCID: PMC4971894 DOI: 10.1152/ajpendo.00207.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During fasting, human skeletal muscle depends on lipid oxidation for its energy substrate metabolism. This is associated with the development of insulin resistance and a subsequent reduction of insulin-stimulated glucose uptake. The underlying mechanisms controlling insulin action on skeletal muscle under these conditions are unresolved. In a randomized design, we investigated eight healthy subjects after a 72-h fast compared with a 10-h overnight fast. Insulin action on skeletal muscle was assessed by a hyperinsulinemic euglycemic clamp and by determining insulin signaling to glucose transport. In addition, substrate oxidation, skeletal muscle lipid content, regulation of glycogen synthesis, and AMPK signaling were assessed. Skeletal muscle insulin sensitivity was reduced profoundly in response to a 72-h fast and substrate oxidation shifted to predominantly lipid oxidation. This was associated with accumulation of both lipid and glycogen in skeletal muscle. Intracellular insulin signaling to glucose transport was impaired by regulation of phosphorylation at specific sites on AS160 but not TBC1D1, both key regulators of glucose uptake. In contrast, fasting did not impact phosphorylation of AMPK or insulin regulation of Akt, both of which are established upstream kinases of AS160. These findings show that insulin resistance in muscles from healthy individuals is associated with suppression of site-specific phosphorylation of AS160, without Akt or AMPK being affected. This impairment of AS160 phosphorylation, in combination with glycogen accumulation and increased intramuscular lipid content, may provide the underlying mechanisms for resistance to insulin in skeletal muscle after a prolonged fast.
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Affiliation(s)
| | - B. F. F. Clasen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| | - J. T. Treebak
- 3Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen;
| | - L. Møller
- Departments of 1Internal Medicine and Endocrinology and
| | | | - M. Madsen
- Departments of 1Internal Medicine and Endocrinology and
| | - T. S. Nielsen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| | | | | | | | - L. J. Goodyear
- 5Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - J. F. P. Wojtaszewski
- 3Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen;
| | - N. Møller
- Departments of 1Internal Medicine and Endocrinology and
| | - N. Jessen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
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Abstract
AIM The aim of this study was to test the hypothesis that interleukin (IL)-6 plays a role in exercise-induced peroxisome proliferator-activated receptor γ co-activator (PGC)-1α and tumor necrosis factor (TNF)-α mRNA responses in skeletal muscle and to examine the potential IL-6-mediated AMP-activated protein kinase (AMPK) regulation in these responses. METHODS Whole body IL-6 knockout (KO) and wildtype (WT) male mice (4 months of age) performed 1 h treadmill exercise. White gastrocnemius (WG) and quadriceps (Quad) muscles were removed immediately (0') or 4 h after exercise and from mice not run acutely. RESULTS Acute exercise reduced only in WT muscle glycogen concentration to 55 and 35% (P < 0.05) of resting level in Quad and WG respectively. While AMPK and Acetyl CoA carboxylase (ACC) phosphorylation increased 1.3-fold (P < 0.05) in WG and twofold in Quad immediately after exercise in WT mice, no change was detected in WG in IL-6 KO mice. The PGC-1α mRNA content was in resting WG 1.8-fold higher (P < 0.05) in WT mice than in IL-6 KO mice. Exercise induced a delayed PGC-1α mRNA increase in Quad in IL-6 KO mice (12-fold at 4 h) relative to WT mice (fivefold at 0'). The TNF-α mRNA content was in resting Quad twofold higher (P < 0.05) in IL-6 KO than in WT, and WG TNF-α mRNA increased twofold (P < 0.05) immediately after exercise only in IL-6 KO. CONCLUSION In conclusion, IL-6 affects exercise-induced glycogen use, AMPK signalling and TNF-α mRNA responses in mouse skeletal muscle.
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Affiliation(s)
- H Adser
- Centre of Inflammation and Metabolism, Copenhagen, Denmark
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11
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Vind BF, Pehmøller C, Treebak JT, Birk JB, Hey-Mogensen M, Beck-Nielsen H, Zierath JR, Wojtaszewski JFP, Højlund K. Impaired insulin-induced site-specific phosphorylation of TBC1 domain family, member 4 (TBC1D4) in skeletal muscle of type 2 diabetes patients is restored by endurance exercise-training. Diabetologia 2011; 54:157-67. [PMID: 20938636 DOI: 10.1007/s00125-010-1924-4] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 09/03/2010] [Indexed: 12/26/2022]
Abstract
AIMS/HYPOTHESIS Insulin-mediated glucose disposal rates (R(d)) are reduced in type 2 diabetic patients, a process in which intrinsic signalling defects are thought to be involved. Phosphorylation of TBC1 domain family, member 4 (TBC1D4) is at present the most distal insulin receptor signalling event linked to glucose transport. In this study, we examined insulin action on site-specific phosphorylation of TBC1D4 and the effect of exercise training on insulin action and signalling to TBC1D4 in skeletal muscle from type 2 diabetic patients. METHODS During a 3 h euglycaemic-hyperinsulinaemic (80 mU min⁻¹ m⁻²) clamp, we obtained M. vastus lateralis biopsies from 13 obese type 2 diabetic and 13 obese, non-diabetic control individuals before and after 10 weeks of endurance exercise-training. RESULTS Before training, reductions in insulin-stimulated R (d), together with impaired insulin-stimulated glycogen synthase fractional velocity, Akt Thr³⁰⁸ phosphorylation and phosphorylation of TBC1D4 at Ser³¹⁸, Ser⁵⁸⁸ and Ser⁷⁵¹ were observed in skeletal muscle from diabetic patients. Interestingly, exercise-training normalised insulin-induced TBC1D4 phosphorylation in diabetic patients. This happened independently of increased TBC1D4 protein content, but exercise-training did not normalise Akt phosphorylation in diabetic patients. In both groups, training-induced improvements in insulin-stimulated R(d) (~20%) were associated with increased muscle protein content of Akt, TBC1D4, α2-AMP-activated kinase (AMPK), glycogen synthase, hexokinase II and GLUT4 (20-75%). CONCLUSIONS/INTERPRETATION Impaired insulin-induced site-specific TBC1D4 phosphorylation may contribute to skeletal muscle insulin resistance in type 2 diabetes. The mechanisms by which exercise-training improves insulin sensitivity in type 2 diabetes may involve augmented signalling of TBC1D4 and increased skeletal muscle content of key insulin signalling and effector proteins, e.g., Akt, TBC1D4, AMPK, glycogen synthase, GLUT4 and hexokinase II.
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Affiliation(s)
- B F Vind
- Diabetes Research Center, Department of Endocrinology, Odense University Hospital, Denmark
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12
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Friedrichsen M, Poulsen P, Richter EA, Hansen BF, Birk JB, Ribel-Madsen R, Stender-Petersen K, Nilsson E, Beck-Nielsen H, Vaag A, Wojtaszewski JFP. Differential aetiology and impact of phosphoinositide 3-kinase (PI3K) and Akt signalling in skeletal muscle on in vivo insulin action. Diabetologia 2010; 53:1998-2007. [PMID: 20512309 DOI: 10.1007/s00125-010-1795-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 04/22/2010] [Indexed: 01/04/2023]
Abstract
AIMS/HYPOTHESIS Insulin resistance in skeletal muscle is a key factor in the development of type 2 diabetes and although some studies indicate that this could be partly attributed to reduced content and activity of various proximal and distal insulin signalling molecules, consensus is lacking. We therefore aimed to investigate the regulation of proximal insulin signalling in skeletal muscle and its effect on glucose metabolism in a large non-diabetic population. METHODS We examined 184 non-diabetic twins with gold-standard techniques including the euglycaemic-hyperinsulinaemic clamp. Insulin signalling was evaluated at three key levels, i.e. the insulin receptor, IRS-1 and V-akt murine thymoma viral oncogene (Akt) levels, employing kinase assays and phospho-specific western blotting. RESULTS Proximal insulin signalling was not associated with obesity, age or sex. However, birthweight was positively associated with IRS-1-associated phosphoinositide 3-kinase (PI3K; IRS-1-PI3K) activity (p = 0.04); maximal aerobic capacity (VO2(max)), paradoxically, was negatively associated with IRS-1-PI3K (p = 0.02) and Akt2 activity (p = 0.01). Additionally, we found low heritability estimates for most measures of insulin signalling activity. Glucose disposal was positively associated with Akt-308 phosphorylation (p < 0.001) and Akt2 activity (p = 0.05), but not with insulin receptor tyrosine kinase or IRS-1-PI3K activity. CONCLUSIONS/INTERPRETATION With the exception of birthweight, 'classical' modifiers of insulin action, including genetics, age, sex, obesity and VO2(max) do not seem to mediate their most central effects on whole-body insulin sensitivity through modulation of proximal insulin signalling in skeletal muscle. We also demonstrated an association between Akt activity and in vivo insulin sensitivity, suggesting a role of Akt in control of in vivo insulin resistance and potentially in type 2 diabetes.
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Affiliation(s)
- M Friedrichsen
- Steno Diabetes Center, Niels Steensens Vej 1, Gentofte, Denmark.
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13
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Leick L, Plomgaard P, Grønlykke L, Al-Abaiji F, Wojtaszewski JFP, Pilegaard H. Endurance exercise induces mRNA expression of oxidative enzymes in human skeletal muscle late in recovery. Scand J Med Sci Sports 2010; 20:593-9. [DOI: 10.1111/j.1600-0838.2009.00988.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Jensen TE, Wojtaszewski JFP, Richter EA. AMP-activated protein kinase in contraction regulation of skeletal muscle metabolism: necessary and/or sufficient? Acta Physiol (Oxf) 2009; 196:155-74. [PMID: 19243572 DOI: 10.1111/j.1748-1716.2009.01979.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In skeletal muscle, the contraction-activated heterotrimeric 5'-AMP-activated protein kinase (AMPK) protein is proposed to regulate the balance between anabolic and catabolic processes by increasing substrate uptake and turnover in addition to regulating the transcription of proteins involved in mitochondrial biogenesis and other aspects of promoting an oxidative muscle phenotype. Here, the current knowledge on the expression of AMPK subunits in human quadriceps muscle and evidence from rodent studies suggesting distinct AMPK subunit expression pattern in different muscle types is reviewed. Then, the intensity and time dependence of AMPK activation in human quadriceps and rodent muscle are evaluated. Subsequently, a major part of this review critically examines the evidence supporting a necessary and/or sufficient role of AMPK in a broad spectrum of skeletal muscle contraction-relevant processes. These include glucose uptake, glycogen synthesis, post-exercise insulin sensitivity, fatty acid (FA) uptake, intramuscular triacylglyceride hydrolysis, FA oxidation, suppression of protein synthesis, proteolysis, autophagy and transcriptional regulation of genes relevant to promoting an oxidative phenotype.
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Affiliation(s)
- T E Jensen
- Molecular Physiology Group, Copenhagen Muscle Research Centre, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
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16
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Treebak JT, Frøsig C, Pehmøller C, Chen S, Maarbjerg SJ, Brandt N, MacKintosh C, Zierath JR, Hardie DG, Kiens B, Richter EA, Pilegaard H, Wojtaszewski JFP. Potential role of TBC1D4 in enhanced post-exercise insulin action in human skeletal muscle. Diabetologia 2009; 52:891-900. [PMID: 19252894 PMCID: PMC3627047 DOI: 10.1007/s00125-009-1294-y] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 01/22/2009] [Indexed: 11/25/2022]
Abstract
AIMS/HYPOTHESIS TBC1 domain family, member 4 (TBC1D4; also known as AS160) is a cellular signalling intermediate to glucose transport regulated by insulin-dependent and -independent mechanisms. Skeletal muscle insulin sensitivity is increased after acute exercise by an unknown mechanism that does not involve modulation at proximal insulin signalling intermediates. We hypothesised that signalling through TBC1D4 is involved in this effect of exercise as it is a common signalling element for insulin and exercise. METHODS Insulin-regulated glucose metabolism was evaluated in 12 healthy moderately trained young men 4 h after one-legged exercise at basal and during a euglycaemic-hyperinsulinaemic clamp. Vastus lateralis biopsies were taken before and immediately after the clamp. RESULTS Insulin stimulation increased glucose uptake in both legs, with greater effects (approximately 80%, p < 0.01) in the previously exercised leg. TBC1D4 phosphorylation, assessed using the phospho-AKT (protein kinase B)substrate antibody and phospho- and site-specific antibodies targeting six phosphorylation sites on TBC1D4, increased at similar degrees to insulin stimulation in the previously exercised and rested legs (p < 0.01). However, TBC1D4 phosphorylation on Ser-318, Ser-341, Ser-588 and Ser-751 was higher in the previously exercised leg, both in the absence and in the presence of insulin (p < 0.01; Ser-588, p = 0.09; observed power = 0.39). 14-3-3 binding capacity for TBC1D4 increased equally (p < 0.01) in both legs during insulin stimulation. CONCLUSION/INTERPRETATION We provide evidence for site-specific phosphorylation of TBC1D4 in human skeletal muscle in response to physiological hyperinsulinaemia. The data support the idea that TBC1D4 is a nexus for insulin- and exercise-responsive signals that may mediate increased insulin action after exercise.
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Affiliation(s)
- J T Treebak
- Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
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17
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Abstract
5'AMP-activated protein kinase (AMPK) is recognized as an important intracellular energy sensor, shutting down energy-consuming processes and turning on energy-generating processes. Discovery of target proteins of AMPK has dramatically increased in the past 10 years. Historically, AMPK was first shown to regulate fatty acid and cholesterol synthesis, but is now hypothesized to take part in the regulation of energy/fuel balance not only at the cellular level but also at the level of the whole organism. In this brief review we will discuss some of the roles of AMPK in skeletal muscle.
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Affiliation(s)
- J T Treebak
- Molecular Physiology Group, Copenhagen Muscle Research Centre, Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Abstract
5'AMP-activated protein kinase (AMPK) is a key regulator of cellular metabolism and is regulated in muscle during exercise. We have previously established that only three of 12 possible AMPK alpha/beta/gamma-heterotrimers are present in human skeletal muscle. Previous studies describe discrepancies between total AMPK activity and regulation of its target acetyl-CoA-carboxylase (ACC)beta. Also, exercise training decreases expression of the regulatory gamma3 AMPK subunit and attenuates alpha2 AMPK activity during exercise. We hypothesize that these observations reflect a differential regulation of the AMPK heterotrimers. We provide evidence here that only the alpha2/beta2/gamma3 subunit is phosphorylated and activated during high-intensity exercise in vivo. The activity associated with the remaining two AMPK heterotrimers, alpha1/beta2/gamma1 and alpha2/beta2/gamma1, is either unchanged (20 min, 80% maximal oxygen uptake ) or decreased (30 or 120 s sprint-exercise). The differential activity of the heterotrimers leads to a total alpha-AMPK activity, that is decreased (30 s trial), unchanged (120 s trial) and increased (20 min trial). AMPK activity associated with the alpha2/beta2/gamma3 heterotrimer was strongly correlated to gamma3-associated alpha-Thr-172 AMPK phosphorylation (r(2) = 0.84, P < 0.001) and to ACCbeta Ser-221 phosphorylation (r(2) = 0.65, P < 0.001). These data single out the alpha2/beta2/gamma3 heterotrimer as an important actor in exercise-regulated AMPK signalling in human skeletal muscle, probably mediating phosphorylation of ACCbeta.
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Affiliation(s)
- J B Birk
- Copenhagen Muscle Research Centre, Department of Human Physiology, Institute of Exercise and Sport Sciences, University of Copenhagen, 13 Universitetsparken, 2100 Copenhagen Ø, Denmark.
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19
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Højlund K, Wojtaszewski JFP, Birk J, Hansen BF, Vestergaard H, Beck-Nielsen H. Partial rescue of in vivo insulin signalling in skeletal muscle by impaired insulin clearance in heterozygous carriers of a mutation in the insulin receptor gene. Diabetologia 2006; 49:1827-37. [PMID: 16761106 DOI: 10.1007/s00125-006-0312-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Accepted: 04/24/2006] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS Recently we reported the coexistence of postprandial hypoglycaemia and moderate insulin resistance in heterozygous carriers of the Arg1174Gln mutation in the insulin receptor gene (INSR). Controlled studies of in vivo insulin signalling in humans with mutant INSR are unavailable, and therefore the cellular mechanisms underlying insulin resistance in Arg1174Gln carriers remain to be clarified. SUBJECTS, MATERIALS AND METHODS We studied glucose metabolism and insulin signalling in skeletal muscle from six Arg1174Gln carriers and matched control subjects during a euglycaemic-hyperinsulinaemic clamp. RESULTS Impaired clearance of exogenous insulin caused four-fold higher clamp insulin levels in Arg1174Gln carriers compared with control subjects (p<0.05). In Arg1174Gln carriers insulin increased glucose disposal and non-oxidative glucose metabolism (p<0.05), but to a lower extent than in controls (p<0.05). Insulin increased Akt phosphorylation at Ser473 and Thr308, inhibited glycogen synthase kinase-3alpha activity, reduced phosphorylation of glycogen synthase at sites 3a+3b, and increased glycogen synthase activity in Arg1174Gln carriers (all p<0.05). In the insulin-stimulated state, Akt phosphorylation at Thr308 and glycogen synthase activity were reduced in Arg1174Gln carriers compared with controls (p<0.05), whereas glycogen synthase kinase-3alpha activity and phosphorylation of glycogen synthase at sites 3a+3b were similar in the two groups. CONCLUSIONS/INTERPRETATION In vivo insulin signalling in skeletal muscle of patients harbouring the Arg1174Gln mutation is surprisingly intact, with modest impairments in insulin-stimulated activity of Akt and glycogen synthase explaining the moderate degree of insulin resistance. Our data suggest that impaired insulin clearance in part rescues in vivo insulin signalling in muscle in these carriers of a mutant INSR, probably by increasing insulin action on the non-mutated insulin receptors.
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Affiliation(s)
- K Højlund
- Diabetes Research Centre, Department of Endocrinology, Odense University Hospital, Odense, Denmark
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20
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Højlund K, Frystyk J, Levin K, Flyvbjerg A, Wojtaszewski JFP, Beck-Nielsen H. Reduced plasma adiponectin concentrations may contribute to impaired insulin activation of glycogen synthase in skeletal muscle of patients with type 2 diabetes. Diabetologia 2006; 49:1283-91. [PMID: 16609880 DOI: 10.1007/s00125-006-0240-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Accepted: 02/13/2006] [Indexed: 10/24/2022]
Abstract
AIMS/HYPOTHESIS Circulating levels of adiponectin are negatively associated with multiple indices of insulin resistance, and the concentration is reduced in humans with insulin resistance and type 2 diabetes. However, the mechanisms by which adiponectin improves insulin sensitivity remain unclear. SUBJECTS AND METHODS Combining euglycaemic-hyperinsulinaemic clamp studies with indirect calorimetry and skeletal muscle biopsies, we examined the relationship between plasma adiponectin and parameters of whole-body glucose and lipid metabolism, and muscle glycogen synthase (GS) activity in 51 Caucasians (ten lean, 21 obese and 20 with type 2 diabetes). RESULTS Plasma adiponectin was significantly reduced in type 2 diabetic compared with obese and lean subjects. In lean and obese subjects, insulin significantly reduced plasma adiponectin, but this response was blunted in patients with type 2 diabetes. Plasma adiponectin was positively associated with insulin-stimulated glucose disposal (r = 0.48), glucose oxidation (r = 0.54), respiratory quotient (r = 0.58) and non-oxidative glucose metabolism (r = 0.38), and negatively associated with lipid oxidation during insulin stimulation (r = -0.60) after adjustment for body fat (all p < 0.01). Most notably, we found a positive association between plasma adiponectin and insulin stimulation of GS activity in skeletal muscle (r = 0.44, p < 0.01). CONCLUSIONS/INTERPRETATION Our results indicate that plasma adiponectin may enhance insulin sensitivity by improving the capacity to switch from lipid to glucose oxidation and to store glucose as glycogen in response to insulin, and that low adiponectin may contribute to impaired insulin activation of GS in skeletal muscle of patients with type 2 diabetes.
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Affiliation(s)
- K Højlund
- Diabetes Research Centre, Department of Endocrinology, Odense University Hospital, Odense, Denmark.
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21
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Wojtaszewski JFP, Nielsen JN, Jørgensen SB, Frøsig C, Birk JB, Richter EA. Transgenic models – a scientific tool to understand exercise-induced metabolism: the regulatory role of AMPK (5′-AMP-activated protein kinase) in glucose transport and glycogen synthase activity in skeletal muscle. Biochem Soc Trans 2003; 31:1290-4. [PMID: 14641045 DOI: 10.1042/bst0311290] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The AMPK (5´AMP-activated protein kinase) is becoming recognized as a critical regulator of energy metabolism. However, many of these effects in muscle metabolism have been ascribed to AMPK based on the use of the unspecific activator AICAR (5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside). Using mouse models in which AMPK activity has been specifically blocked (kinase dead) or knocked out we and others have been able to conduct studies gaining more conclusive data on the role of AMPK in muscle metabolism. In this mini-review focus is on AMPK and its regulatory role for glucose transport and GS (glycogen synthase) activity in skeletal muscle, indicating that AMPK is a GS kinase in vivo which might influence GS activity during exercise and that AMPK is involved in AICAR/hypoxia-induced glucose transport but not or only partially in contraction-stimulated glucose transport.
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Affiliation(s)
- J F P Wojtaszewski
- Copenhagen Muscle Research Centre, Institute of Exercise and Sport Sciences, University of Copenhagen, 13 Universitetsparken, 2100-Copenhagen, Denmark.
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22
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Abstract
After the discovery and clinical use of insulin for treatment of diabetes it became clear that some of the biological effect of insulin was dependent on the circumstances under which it was given. Relevant for this review is the notion that physical activity, in addition to its own direct metabolic effects also markedly affects the ability of insulin to stimulate a range of metabolic processes. More specifically, during and for a prolonged period after, exercise elicits effects on processes such as insulin-induced muscle glucose uptake and glucose metabolism which influence systemic glucose homeostasis. These phenomena are probably responsible for the improvement in glucose homeostasis and metabolic control that typically occurs with exercise in people with insulin resistance and probably contributes to the reduced risk for development of type 2 diabetes in individuals who engage in regular exercise. Here we focus on the influence of a single bout of exercise on the action of insulin on processes such as glucose uptake and glucose storage in skeletal muscle.
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Affiliation(s)
- J F P Wojtaszewski
- Copenhagen Muscle research Centre, Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
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23
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Richter EA, Nielsen JN, Jørgensen SB, Frøsig C, Wojtaszewski JFP. Signalling to glucose transport in skeletal muscle during exercise. Acta Physiol Scand 2003; 178:329-35. [PMID: 12864737 DOI: 10.1046/j.1365-201x.2003.01153.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Exercise-induced glucose uptake in skeletal muscle is mediated by an insulin-independent mechanism. Although the signalling events that increase glucose transport in response to muscle contraction are not fully elucidated, the aim of the present review is to briefly present the current understanding of the molecular signalling mechanisms involved. Glucose uptake may be regulated by Ca++-sensitive contraction-related mechanisms possibly involving protein kinase C, and by mechanisms that reflect the metabolic status of the muscle and may involve the AMP-activated protein kinase. Furthermore the p38 mitogen activated protein kinase may be involved. Still, the picture is incomplete and a substantial part of the exercise/contraction-induced signalling mechanism to glucose transport remains unknown.
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Affiliation(s)
- E A Richter
- Copenhagen Muscle Research Centre, Department of Human Physiology, Institute of Exercise and Sports Sciences, University of Copenhagen, Denmark
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24
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Viollet B, Andreelli F, Jørgensen SB, Perrin C, Flamez D, Mu J, Wojtaszewski JFP, Schuit FC, Birnbaum M, Richter E, Burcelin R, Vaulont S. Physiological role of AMP-activated protein kinase (AMPK): insights from knockout mouse models. Biochem Soc Trans 2003; 31:216-9. [PMID: 12546688 DOI: 10.1042/bst0310216] [Citation(s) in RCA: 192] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AMP-activated protein kinase (AMPK) is viewed as a fuel sensor for glucose and lipid metabolism. To understand better the physiological role of the catalytic AMPK subunit isoforms, we generated two knockout mouse models with the alpha1 (AMPK alpha 1(-/-)) and alpha 2 (AMPK alpha 2(-/-)) catalytic subunit genes deleted. No defect in glucose homoeostasis was observed in AMPK alpha 1(-/-) mice. On the other hand, AMPK alpha 2(-/-) mice presented high plasma glucose levels and low plasma insulin concentrations in the fed period and during the glucose tolerance test. Nevertheless, in isolated AMPK alpha 2(-/-) pancreatic islets, glucose-stimulated insulin secretion was not affected. Surprisingly, AMPK alpha 2(-/-) mice were insulin-resistant and had reduced muscle glycogen synthesis as assessed in vivo by the hyperinsulinaemic euglycaemic clamp procedure. Reduction of insulin sensitivity and glycogen synthesis were not dependent on the lack of AMPK in skeletal muscle, since mice expressing a dominant inhibitory mutant of AMPK in skeletal muscle were not affected and since insulin-stimulated glucose transport in incubated muscles in vitro was normal in AMPK alpha 2(-/-) muscles. Furthermore, AMPK alpha 2(-/-) mice have a higher sympathetic tone, as shown by increased catecholamine urinary excretion. Increased adrenergic tone could explain both decreased insulin secretion and insulin resistance observed in vivo in AMPK alpha 2(-/-) mice. We suggest that the alpha2 catalytic subunit of AMPK plays a major role as a fuel sensor by modulating the activity of the autonomous nervous system in vivo.
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Affiliation(s)
- B Viollet
- Institut Cochin, Dpt GDPM, 24 rue du faubourg Saint-Jacques 75014 Paris, France.
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25
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Nielsen JN, Jørgensen SB, Frøsig C, Viollet B, Andreelli F, Vaulont S, Kiens B, Richter EA, Wojtaszewski JFP. A possible role for AMP-activated protein kinase in exercise-induced glucose utilization: insights from humans and transgenic animals. Biochem Soc Trans 2003; 31:186-90. [PMID: 12546682 DOI: 10.1042/bst0310186] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Exercise-induced glucose uptake in skeletal muscle is mediated by an insulin-independent mechanism, but the actual signals to glucose transport in response to muscle contraction have not been identified. The 5'-AMP-activated protein kinase (AMPK) has emerged as a putative mediator of contraction-induced glucose transport, although no conclusive evidence has been provided so far. Recent experiments in AMPK transgenic mice suggest that glucose transport induced by 5-amino-4-imidazolecarboxamide riboside (AICAR) or hypoxia is mediated by AMPK. In contrast, contraction-induced glucose transport in rodent skeletal muscle induced by electrical stimulation in vitro or in situ is not influenced or is only partially reduced by abolishing both or one of the catalytic AMPK subunits. This is compatible with exercise studies done in humans, where no tight correlation is found between AMPK activity and glucose uptake during exercise. Taken together, these results question an essential role of AMPK in exercise-induced glucose uptake and imply that one or more additional pathways are involved in mediating glucose transport in skeletal muscle during exercise.
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Affiliation(s)
- J N Nielsen
- Copenhagen Muscle Research Centre, Institute of Exercise and Sports Sciences, Department of Human Physiology, University of Copenhagen, Denmark.
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