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Tobias IS, Galpin AJ. Moving human muscle physiology research forward: an evaluation of fiber type-specific protein research methodologies. Am J Physiol Cell Physiol 2020; 319:C858-C876. [DOI: 10.1152/ajpcell.00107.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skeletal muscle is a heterogeneous tissue composed of multiple fiber types that express unique contractile and metabolic properties. While analysis of mixed fiber samples predominates and holds value, increasing attention has been directed toward studying proteins segregated by fiber type, a methodological distinction termed “fiber type-specific.” Fiber type-specific protein studies have the advantage of uncovering key molecular effects that are often missed in mixed fiber homogenate studies but also require greater time and resource-intensive methods, particularly when applied to human muscle. This review summarizes and compares current methods used for fiber type-specific protein analysis, highlighting their advantages and disadvantages for human muscle studies, in addition to recent advances in these techniques. These methods can be grouped into three categories based on the initial processing of the tissue: 1) muscle-specific fiber homogenates, 2) cross sections of fiber bundles, and 3) isolated single fibers, with various subtechniques for performing fiber type identification and protein quantification. The relative implementation for each unique methodological approach is analyzed from 83 fiber type-specific studies of proteins in live human muscle found in the literature to date. These studies have investigated several proteins involved in a wide range of cellular functions that are important to muscle tissue. The second half of this review summarizes key findings from this ensemble of fiber type-specific human protein studies. We highlight examples of where this analytical approach has helped to improve understanding of important physiological topics such as insulin sensitivity, muscle hypertrophy, muscle fatigue, and adaptation to different exercise programs.
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Affiliation(s)
- Irene S. Tobias
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
| | - Andrew J. Galpin
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
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Phielix E, Begovatz P, Gancheva S, Bierwagen A, Kornips E, Schaart G, Hesselink MKC, Schrauwen P, Roden M. Athletes feature greater rates of muscle glucose transport and glycogen synthesis during lipid infusion. JCI Insight 2019; 4:127928. [PMID: 31672941 DOI: 10.1172/jci.insight.127928] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 10/02/2019] [Indexed: 01/13/2023] Open
Abstract
BACKGROUNDInsulin resistance results from impaired skeletal muscle glucose transport/phosphorylation, linked to augmented lipid availability. Despite greater intramuscular lipids, athletes are highly insulin sensitive, which could result from higher rates of insulin-stimulated glycogen synthesis or glucose transport/phosphorylation and oxidation. Thus, we examined the time course of muscle glycogen and glucose-6-phosphate concentrations during low and high systemic lipid availability.METHODSEight endurance-trained and 9 sedentary humans (VO2 peak: 56 ± 2 vs. 33 ± 2 mL/kg/min, P < 0.05) underwent 6-hour hyperinsulinemic-isoglycemic clamp tests with infusions of triglycerides or saline in a randomized crossover design. Glycogen and glucose-6-phosphate concentrations were monitored in vastus lateralis muscles using 13C/31P magnetic resonance spectroscopy.RESULTSAthletes displayed a 25% greater (P < 0.05) insulin-stimulated glucose disposal rate (Rd) than sedentary participants. During Intralipid infusion, insulin sensitivity remained higher in the athletes (ΔRd: 25 ± 3 vs. 17 ± 3 μmol/kg/min, P < 0.05), supported by higher glucose transporter type 4 protein expression than in sedentary humans. Compared to saline infusion, AUC of glucose-6-phosphate remained unchanged during Intralipid infusion in athletes (1.6 ± 0.2 mmol/L vs. 1.4 ± 0.2 [mmol/L] × h, P = n.s.) but tended to decrease by 36% in sedentary humans (1.7 ± 0.4 vs. 1.1 ± 0.1 [mmol/L] × h, P < 0.059). This drop was accompanied by a 72% higher rate of net glycogen synthesis in the athletes upon Intralipid infusion (47 ± 9 vs. 13 ± 3 μmol/kg/min, P < 0.05).CONCLUSIONAthletes feature higher skeletal muscle glucose disposal and glycogen synthesis during increased lipid availability, which primarily results from maintained insulin-stimulated glucose transport with increased myocellular glucose-6-phosphate levels for subsequent glycogen synthesis.TRIAL REGISTRATIONClinicalTrials.gov NCT01229059.FUNDINGGerman Federal Ministry of Health (BMG).
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Affiliation(s)
- Esther Phielix
- Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany.,Department of Nutrition and Movement Sciences, School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands
| | - Paul Begovatz
- Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Sofiya Gancheva
- Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Alessandra Bierwagen
- Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Esther Kornips
- Department of Nutrition and Movement Sciences, School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands
| | - Gert Schaart
- Department of Nutrition and Movement Sciences, School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands
| | - Matthijs K C Hesselink
- Department of Nutrition and Movement Sciences, School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, Netherlands
| | - Michael Roden
- Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
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Duan Y, Li F, Wang W, Guo Q, Wen C, Yin Y. Alteration of muscle fiber characteristics and the AMPK-SIRT1-PGC-1α axis in skeletal muscle of growing pigs fed low-protein diets with varying branched-chain amino acid ratios. Oncotarget 2017; 8:107011-107021. [PMID: 29291007 PMCID: PMC5739792 DOI: 10.18632/oncotarget.22205] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 09/05/2017] [Indexed: 12/14/2022] Open
Abstract
There mainly exists four major myosin heavy chains (MyHC) (i.e., I, IIa, IIx, and IIb) in growing pigs. The current study aimed to explore the effects of low-protein diets supplemented with varying branched-chain amino acids (BCAAs) on muscle fiber characteristics and the AMPK-SIRT1-PGC-1α axis in skeletal muscles. Forty growing pigs (9.85 ± 0.35 kg) were allotted to 5 groups and fed with diets supplemented with varying leucine: isoleucine: valine ratios: 1:0.51:0.63 (20% crude protein, CP), 1:1:1 (17% CP), 1:0.75:0.75 (17% CP), 1:0.51:0.63 (17% CP), and 1:0.25:0.25 (17% CP), respectively. The skeletal muscles of different muscle fiber composition, that is, longissimus dorsi muscle (LM, a fast-twitch glycolytic muscle), biceps femoris muscle (BM, a mixed slow- and fast-twitch oxido-glycolytic muscle), and psoas major muscle (PM, a slow-twitch oxidative muscle) were collected and analyzed. Results showed that relative to the control group (1:0.51:0.63, 20% CP), the low-protein diets with the leucine: isoleucine: valine ratio ranging from 1:0.75:0.75 to 1:0.25:0.25 especially augmented the mRNA and protein abundance of MyHC I fibers in BM and lowered the mRNA abundance of MyHC IIb particularly in LM (P < 0.05), with a concurrent increase in the activation of AMPK and the mRNA abundance of SIRT and PGC-1α in BM (P < 0.05). The results reveal that low-protein diets supplemented with optimal BCAA ratio, i.e. 1:0.75:0.75-1:0.25:0.25, induce muscle more oxidative especially in oxido-glycolytic skeletal muscle of growing pigs. These effects are likely associated with the activation of the AMPK-SIRT1-PGC-1α axis.
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Affiliation(s)
- Yehui Duan
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Institute of Subtropical Agriculture Chinese Academy of Sciences, Key Laboratory of Agro-Ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Fengna Li
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Institute of Subtropical Agriculture Chinese Academy of Sciences, Key Laboratory of Agro-Ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China.,Hunan Co-Innovation Center of Animal Production Safety, CICAPS, Hunan Collaborative Innovation Center for Utilization of Botanical Functional Ingredients, Changsha, Hunan, China
| | - Wenlong Wang
- Laboratory of Animal Nutrition and Human Health, School of Biology, Hunan Normal University, Changsha, Hunan, China
| | - Qiuping Guo
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Institute of Subtropical Agriculture Chinese Academy of Sciences, Key Laboratory of Agro-Ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Chaoyue Wen
- Laboratory of Animal Nutrition and Human Health, School of Biology, Hunan Normal University, Changsha, Hunan, China
| | - Yulong Yin
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Institute of Subtropical Agriculture Chinese Academy of Sciences, Key Laboratory of Agro-Ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China.,Laboratory of Animal Nutrition and Human Health, School of Biology, Hunan Normal University, Changsha, Hunan, China
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Bouwman FG, Wang P, van Baak M, Saris WHM, Mariman ECM. Increased β-oxidation with improved glucose uptake capacity in adipose tissue from obese after weight loss and maintenance. Obesity (Silver Spring) 2014; 22:819-27. [PMID: 23512564 DOI: 10.1002/oby.20359] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 12/19/2012] [Indexed: 12/12/2022]
Abstract
OBJECTIVE We investigated protein markers for pathways of the fatty acids (FAs) and glucose metabolism in human adipose tissue after a weight loss program by calorie restriction. METHODS Overweight/obese subjects underwent an intervention of 5 weeks of a very low-calorie diet followed by a 3-week weight maintenance diet. Abdominal subcutaneous adipose tissue biopsies were sampled before and after the intervention. Seventeen target proteins as markers of metabolic pathways for the uptake and handling of FAs and glucose were quantified by Western blotting and 11 were retrieved from previous proteomics work. Correlation coefficients were calculated among changes of these proteins. RESULTS Short-chain 3-hydroxyacyl-CoA dehydrogenase, catalase, fatty acid translocase, fatty acid transporter protein 3, adipose triglyceride lipase, fatty acid-binding protein 4, aldolase-C, tubulin-β-5, and annexin A2 changed significantly, and lipoprotein lipase, perilipin 1, and hormone-sensitive lipase tended to change. On an average, increased glucose transporter type 4 translocation was observed, supported by a consistent increase of tyr-24 phosphorylated annexin A2. CONCLUSIONS Our findings suggest that after weight loss by calorie restriction and a short period of maintenance, adipose tissue has an increased capacity for glucose uptake, and lipid mobilization and oxidation. Such metabolic profile may relate to the health benefit of weight loss.
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Affiliation(s)
- Freek G Bouwman
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
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Regional differences in blood flow, glucose uptake and fatty acid uptake within quadriceps femoris muscle during dynamic knee-extension exercise. Eur J Appl Physiol 2013; 113:1775-82. [DOI: 10.1007/s00421-013-2609-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 02/06/2013] [Indexed: 11/27/2022]
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Augmenting muscle diacylglycerol and triacylglycerol content by blocking fatty acid oxidation does not impede insulin sensitivity. Proc Natl Acad Sci U S A 2012; 109:11711-6. [PMID: 22753483 DOI: 10.1073/pnas.1206868109] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A low fat oxidative capacity has been linked to muscle diacylglycerol (DAG) accumulation and insulin resistance. Alternatively, a low fat oxidation rate may stimulate glucose oxidation, thereby enhancing glucose disposal. Here, we investigated whether an ethyl-2-[6-(4-chlorophenoxy)hexyl]-oxirane-2-carboxylate (etomoxir)-induced inhibition of fat oxidation leads to muscle fat storage and insulin resistance. An intervention in healthy male subjects was combined with studies in human primary myotubes. Furthermore, muscle DAG and triacylglycerol (TAG), mitochondrial function, and insulin signaling were examined in etomoxir-treated C57bl6 mice. In humans, etomoxir administration increased glucose oxidation at the expense of fat oxidation. This effect was accompanied by an increased abundance of GLUT4 at the sarcolemma and a lowering of plasma glucose levels, indicative of improved glucose homeostasis. In mice, etomoxir injections resulted in accumulation of muscle TAG and DAG, yet improved insulin-stimulated GLUT4 translocation. Also in human myotubes, insulin signaling was improved by etomoxir, in the presence of increased intramyocellular lipid accumulation. These insulin-sensitizing effects in mice and human myotubes were accompanied by increased phosphorylation of AMP-activated protein kinase (AMPK). Our results show that a reduction in fat oxidation leading to accumulation of muscle DAG does not necessarily lead to insulin resistance, as the reduction in fat oxidation may activate AMPK.
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Sáinz N, Rodríguez A, Catalán V, Becerril S, Ramírez B, Lancha A, Burgos-Ramos E, Gómez-Ambrosi J, Frühbeck G. Leptin reduces the expression and increases the phosphorylation of the negative regulators of GLUT4 traffic TBC1D1 and TBC1D4 in muscle of ob/ob mice. PLoS One 2012; 7:e29389. [PMID: 22253718 PMCID: PMC3253781 DOI: 10.1371/journal.pone.0029389] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 11/28/2011] [Indexed: 02/01/2023] Open
Abstract
Leptin improves insulin sensitivity in skeletal muscle. Our goal was to determine whether proteins controlling GLUT4 traffic are altered by leptin deficiency and in vivo leptin administration in skeletal muscle of wild type and ob/ob mice. Leptin-deficient ob/ob mice were divided in three groups: control, leptin-treated (1 mg/kg/d) and leptin pair-fed ob/ob mice. Microarray analysis revealed that 1,546 and 1,127 genes were regulated by leptin deficiency and leptin treatment, respectively. Among these, we identified 24 genes involved in intracellular vesicle-mediated transport in ob/ob mice. TBC1 domain family, member 1 (Tbc1d1), a negative regulator of GLUT4 translocation, was up-regulated (P = 0.001) in ob/ob mice as compared to wild types. Importantly, leptin treatment reduced the transcript levels of Tbc1d1 (P<0.001) and Tbc1d4 (P = 0.004) in the leptin-treated ob/ob as compared to pair-fed ob/ob animals. In addition, phosphorylation levels of TBC1D1 and TBC1D4 were enhanced in leptin-treated ob/ob as compared to control ob/ob (P = 0.015 and P = 0.023, respectively) and pair-fed ob/ob (P = 0.036 and P = 0.034, respectively) mice. Despite similar GLUT4 protein expression in wild type and ob/ob groups a different immunolocalization of this protein was evidenced in muscle sections. Leptin treatment increased GLUT4 immunoreactivity in gastrocnemius and extensor digitorum longus sections of leptin-treated ob/ob mice. Moreover, GLUT4 protein detected in immunoprecipitates from TBC1D4 was reduced by leptin replacement compared to control ob/ob (P = 0.013) and pair-fed ob/ob (P = 0.037) mice. Our findings suggest that leptin enhances the intracellular GLUT4 transport in skeletal muscle of ob/ob animals by reducing the expression and activity of the negative regulators of GLUT4 traffic TBC1D1 and TBC1D4.
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Affiliation(s)
- Neira Sáinz
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Amaia Rodríguez
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Victoria Catalán
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Sara Becerril
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Beatriz Ramírez
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Andoni Lancha
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Emma Burgos-Ramos
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Gema Frühbeck
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- Department of Endocrinology and Nutrition, Clínica Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
- * E-mail:
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Gaster M. Fibre Type Dependent Expression of Glucose Transporters in Human Skeletal Muscles. APMIS 2008. [DOI: 10.1111/j.1600-0463.2007.apmv115s121.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jazet IM, Schaart G, Gastaldelli A, Ferrannini E, Hesselink MK, Schrauwen P, Romijn JA, Maassen JA, Pijl H, Ouwens DM, Meinders AE. Loss of 50% of excess weight using a very low energy diet improves insulin-stimulated glucose disposal and skeletal muscle insulin signalling in obese insulin-treated type 2 diabetic patients. Diabetologia 2008; 51:309-19. [PMID: 18080107 DOI: 10.1007/s00125-007-0862-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 09/13/2007] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Both energy restriction (ER) per se and weight loss improve glucose metabolism in obese insulin-treated type 2 diabetic patients. Short-term ER decreases basal endogenous glucose production (EGP) but not glucose disposal. In contrast the blood glucose-lowering mechanism of long-term ER with substantial weight loss has not been fully elucidated. The aim of this study was to investigate the effect of loss of 50% of excess weight [50% excess weight reduction (EWR)] on EGP, whole-body insulin sensitivity and the disturbed myocellular insulin-signalling pathway in ten obese insulin-treated type 2 diabetic patients. METHODS A euglycaemic-hyperinsulinaemic clamp with stable isotopes ([6,6-(2)H2]glucose and [2H5]glycerol) combined with skeletal muscle biopsies was performed during a very low energy diet (VLED; 1,883 kJ/day) on day 2 and again after 50% EWR. Oral blood glucose-lowering agents and insulin were discontinued 3 weeks prior to the VLED and at the start of the VLED, respectively. RESULTS Loss of 50% EWR (20.3+/-2.2 kg from day 2 to day of 50% EWR) normalised basal EGP and improved insulin sensitivity, especially insulin-stimulated glucose disposal (18.8+/-2.0 to 39.1+/-2.8 micromol kg fat-free mass(-1) min(-1), p=0.001). The latter was accompanied by improved insulin signalling at the level of the recently discovered protein kinase B/Akt substrates AS160 and PRAS40 along with a decrease in intramyocellular lipid (IMCL) content. CONCLUSIONS/INTERPRETATION Considerable weight loss in obese, insulin-treated type 2 diabetic patients normalises basal EGP and improves insulin sensitivity resulting from an improvement in insulin signal transduction in skeletal muscle. The decrease in IMCL might contribute to this effect.
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Affiliation(s)
- I M Jazet
- Department of General Internal Medicine, C4-r-73, Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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Affiliation(s)
- Michael Gaster
- Institute of Pathology and Department of Endocrinology, Odense University Hospital, 5000 Odense C
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Verdijk LB, Koopman R, Schaart G, Meijer K, Savelberg HHCM, van Loon LJC. Satellite cell content is specifically reduced in type II skeletal muscle fibers in the elderly. Am J Physiol Endocrinol Metab 2007; 292:E151-7. [PMID: 16926381 DOI: 10.1152/ajpendo.00278.2006] [Citation(s) in RCA: 329] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Satellite cells (SC) are essential for skeletal muscle growth and repair. Because sarcopenia is associated with type II muscle fiber atrophy, we hypothesized that SC content is specifically reduced in the type II fibers in the elderly. A total of eight elderly (E; 76 +/- 1 yr) and eight young (Y; 20 +/- 1 yr) healthy males were selected. Muscle biopsies were collected from the vastus lateralis in both legs. ATPase staining and a pax7-antibody were used to determine fiber type-specific SC content (i.e., pax7-positive SC) on serial muscle cross sections. In contrast to the type I fibers, the proportion and mean cross-sectional area of the type II fibers were substantially reduced in E vs. Y. The number of SC per type I fiber was similar in E and Y. However, the number of SC per type II fiber was substantially lower in E vs. Y (0.044 +/- 0.003 vs. 0.080 +/- 0.007; P < 0.01). In addition, in the type II fibers, the number of SC relative to the total number of nuclei and the number of SC per fiber area were also significantly lower in E. This study is the first to show type II fiber atrophy in the elderly to be associated with a fiber type-specific decline in SC content. The latter is evident when SC content is expressed per fiber or per fiber area. The decline in SC content might be an important factor in the etiology of type II muscle fiber atrophy, which accompanies the loss of skeletal muscle with aging.
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Affiliation(s)
- Lex B Verdijk
- Dept. of Movement Sciences, Faculty of Health Sciences, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Jazet IM, Ouwens DM, Schaart G, Pijl H, Keizer H, Maassen JA, Meinders AE. Effect of a 2-day very low-energy diet on skeletal muscle insulin sensitivity in obese type 2 diabetic patients on insulin therapy. Metabolism 2005; 54:1669-78. [PMID: 16311102 DOI: 10.1016/j.metabol.2005.06.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 06/30/2005] [Indexed: 11/29/2022]
Abstract
This study investigates the molecular mechanisms underlying the blood glucose-lowering effect of a 2-day very low-energy diet (VLED, 1883 kJ/d) in 12 obese (body mass index, 36.3 +/- 1.0 kg/m2 [mean +/- SEM]) type 2 diabetic (HbA(1C) 7.3% +/- 0.4%) patients simultaneously taken off all glucose-lowering therapy, including insulin. Endogenous glucose production (EGP) and glucose disposal ([6,6-2H2]-glucose) were measured before and after the VLED in basal and hyperinsulinemic (40 mU/m2 per minute) euglycemic conditions. Insulin signaling and expression of GLUT-4, FAT/CD36, and triglycerides were assessed in muscle biopsies, obtained before the clamp and after 30 minutes of hyperinsulinemia. Fasting plasma glucose decreased from 11.3 +/- 1.3 to 10.3 +/- 1.0 mmol/L because of a decreased basal EGP (14.2 +/- 1.0 to 11.9 +/- 0.7 micromol/kg per minute, P = .009). Insulin-stimulated glucose disposal did not change. No diet effect was found on the expression of the insulin receptor and insulin receptor substrate-1 or on phosphatidylinositol 3'-kinase activity, or on FAT/CD36 expression pattern, GLUT-4 translocation, or triglyceride distribution in either the basal or insulin-stimulated situation. Unexpectedly, basal PKB/Akt phosphorylation on T308 and S473 increased after the diet, at equal protein expression. In conclusion, a 2-day VLED lowers fasting plasma glucose via a decreased basal EGP without an effect on glucose disposal. Accordingly, no changes in activation of phosphatidylinositol 3'-kinase, triglyceride distribution, FAT/CD36 expression, and GLUT-4 translocation were found in skeletal muscle biopsies.
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Affiliation(s)
- Ingrid M Jazet
- Department of General Internal Medicine C-4-66, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands.
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Schaart G, Hesselink RP, Keizer HA, van Kranenburg G, Drost MR, Hesselink MKC. A modified PAS stain combined with immunofluorescence for quantitative analyses of glycogen in muscle sections. Histochem Cell Biol 2004; 122:161-9. [PMID: 15322861 DOI: 10.1007/s00418-004-0690-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2004] [Indexed: 10/26/2022]
Abstract
Simultaneous analyses of glycogen in sections with other subcellular constituents within the same section will provide detailed information on glycogen deposition and the processes involved. To date, staining protocols for quantitative glycogen analyses together with immunofluorescence in the same section are lacking. We aimed to: (1) optimise PAS staining for combination with immunofluorescence, (2) perform quantitative glycogen analyses in tissue sections, (3) evaluate the effect of section thickness on PAS-derived data and (4) examine if semiquantitative glycogen data were convertible to genuine glycogen values. Conventional PAS was successfully modified for combined use with immunofluorescence. Transmitted light microscopic examination of glycogen was successfully followed by semiquantification of glycogen using microdensitometry. Semiquantitative data correlated perfectly with glycogen content measured biochemically in the same sample (r2=0.993, P<0.001). Using a calibration curve (r2=0.945, P<0.001) derived from a custom-made external standard with incremental glycogen content, we converted the semiquantitative data to genuine glycogen values. The converted semiquantitative data were comparable with the glycogen values assessed biochemically (P=0.786). In addition we showed that for valid comparison of glycogen content between sections, thickness should remain constant. In conclusion, the novel protocol permits the combined use of PAS with immunofluorescence and shows valid conversion of data obtained by microdensitometry to genuine glycogen data.
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Affiliation(s)
- Gert Schaart
- Department of Movement Sciences, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
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van Dam KG, van Breda E, Schaart G, van Ginneken MME, Wijnberg ID, de Graaf-Roelfsema E, van der Kolk JH, Keizer HA. Investigation of the expression and localization of glucose transporter 4 and fatty acid translocase/CD36 in equine skeletal muscle. Am J Vet Res 2004; 65:951-6. [PMID: 15281654 DOI: 10.2460/ajvr.2004.65.951] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the expression and localization of glucose transporter 4 (GLUT4) and fatty acid translocase (FAT/CD36) in equine skeletal muscle. SAMPLE POPULATION Muscle biopsy specimens obtained from 5 healthy Dutch Warmblood horses. PROCEDURES Percutaneous biopsy specimens were obtained from the vastus lateralis, pectoralis descendens, and triceps brachii muscles. Cryosections were stained with combinations of GLUT4 and myosin heavy chain (MHC) specific antibodies or FAT/CD36 and MHC antibodies to assess the fiber specific expression of GLUT4 and FAT/CD36 in equine skeletal muscle via indirect immunofluorescent microscopy. RESULTS Immunofluorescent staining revealed that GLUT4 was predominantly expressed in the cytosol of fast type 2B fibers of equine skeletal muscle, although several type 1 fibers in the vastus lateralis muscle were positive for GLUT4. In all muscle fibers examined microscopically, FAT/CD36 was strongly expressed in the sarcolemma and capillaries. Type 1 muscle fibers also expressed small intracellular amounts of FAT/CD36, but no intracellular FAT/CD36 expression was detected in type 2 fibers. CONCLUSIONS AND CLINICAL RELEVANCE In equine skeletal muscle, GLUT4 and FAT/CD36 are expressed in a fiber type selective manner.
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Affiliation(s)
- Klien G van Dam
- Department of Equine Sciences (Medicine Section), Faculty of Veterinary Medicine, Utrecht University, Yalelaan 16, NL-3584 CM Utrecht, The Netherlands
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Vistisen B, Roepstorff K, Roepstorff C, Bonen A, van Deurs B, Kiens B. Sarcolemmal FAT/CD36 in human skeletal muscle colocalizes with caveolin-3 and is more abundant in type 1 than in type 2 fibers. J Lipid Res 2004; 45:603-9. [PMID: 14729862 DOI: 10.1194/jlr.m300424-jlr200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
FAT/CD36 is a transmembrane protein that is thought to facilitate cellular long-chain fatty acid uptake. However, surprisingly little is known about the localization of FAT/CD36 in human skeletal muscle. By confocal immunofluorescence microscopy, we demonstrate high FAT/CD36 expression in endothelial cells and weaker but significant FAT/CD36 expression in sarcolemma in human skeletal muscle. No apparent intracellular staining was observed in the muscle cells. There are indications in the literature that caveolae may be involved in the uptake of fatty acids, possibly as regulators of FAT/CD36 or other fatty acid transporters. We show that in sarcolemma, FAT/CD36 colocalizes with the muscle-specific caveolae marker protein caveolin-3, suggesting that caveolae may regulate cellular fatty acid uptake by FAT/CD36. Furthermore, we provide evidence that FAT/CD36 expression is significantly higher in type 1 compared with type 2 fibers, whereas caveolin-3 expression is significantly higher in type 2 fibers than in type 1 fibers.
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Affiliation(s)
- Bodil Vistisen
- Copenhagen Muscle Research Centre, Department of Medical Anatomy, University of Copenhagen, Copenhagen, Denmark
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van Ginneken MME, Keizer HA, Wijnberg ID, van Dam KG, Schaart G, de Graaf-Roelfsema E, van der Kolk JH, van Breda E. Immunohistochemical identification and fiber type specific localization of protein kinase C isoforms in equine skeletal muscle. Am J Vet Res 2004; 65:69-73. [PMID: 14719705 DOI: 10.2460/ajvr.2004.65.69] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate whether protein kinase C (PKC) isoforms are expressed in equine skeletal muscle and determine their distribution in various types of fibers by use of immunofluorescence microscopy. ANIMALS 5 healthy adult Dutch Warmblood horses. PROCEDURE In each horse, 2 biopsy specimens were obtained from the vastus lateralis muscle. Cryosections of equine muscle were stained with PKC isoform (alpha, beta1, beta2, delta, epsilon, or zeta)-specific polyclonal antibodies and examined by use of a fluorescence microscope. Homogenized muscle samples were evaluated via western blot analysis. RESULTS The PKC alpha, beta1, beta2, delta, epsilon, and zeta isoforms were localized within the fibers of equine skeletal muscle. In addition, PKC alpha and beta2 were detected near or in the plasma membrane of muscle cells. For some PKC isoforms, distribution was specific for fiber type. Staining of cell membranes for PKC alpha was observed predominantly in fibers that reacted positively with myosin heavy chain (MHC)-IIa; PKC delta and epsilon staining were more pronounced in MHC-I-positive fibers. In contrast, MHC-I negative fibers contained more PKC zeta than MHC-I-positive fibers. Distribution of PKC beta1 was equal among the different fiber types. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that PKC isoforms are expressed in equine skeletal muscle in a fiber type-specific manner. Therefore, the involvement of PKC isoforms in signal transduction in equine skeletal muscle might be dependent on fiber type.
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Affiliation(s)
- Mireille M E van Ginneken
- Department of Equine Sciences, Discipline of Internal Medicine, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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Schrauwen P, Hinderling V, Hesselink MKC, Schaart G, Kornips E, Saris WHM, Westerterp-Plantenga M, Langhans W. Etomoxir-induced increase in UCP3 supports a role of uncoupling protein 3 as a mitochondrial fatty acid anion exporter. FASEB J 2002; 16:1688-90. [PMID: 12206997 DOI: 10.1096/fj.02-0275fje] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The physiological function of human uncoupling protein-3 is still unknown. Uncoupling protein-3 is increased during fasting and high-fat feeding. In these situations the availability of fatty acids to the mitochondria exceeds the capacity to metabolize fatty acids, suggesting a role for uncoupling protein-3 in handling of non-metabolizable fatty acids. To test the hypothesis that uncoupling protein-3 acts as a mitochondrial exporter of non-metabolizable fatty acids from the mitochondrial matrix, we gave human subjects Etomoxir (which blocks mitochondrial entry of fatty acids) or placebo in a cross-over design during a 36-h stay in a respiration chamber. Etomoxir inhibited 24-h fat oxidation and fat oxidation during exercise by approximately 14-19%. Surprisingly, uncoupling protein-3 content in human vastus lateralis muscle was markedly up-regulated within 36 h of Etomoxir administration. Up-regulation of uncoupling protein-3 was accompanied by lowered fasting blood glucose and increased translocation of glucose transporter-4. These data support the hypothesis that the physiological function of uncoupling protein-3 is to facilitate the outward transport of non-metabolizable fatty acids from the mitochondrial matrix and thus prevents mitochondria from the potential deleterious effects of high fatty acid levels. In addition our data show that up-regulation of uncoupling protein-3 can be beneficial in the treatment of type 2 diabetes.
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Affiliation(s)
- Patrick Schrauwen
- Nutrition and Toxicology Research Institute Maastricht, Department of Human Biology, Maastricht University, 6200 MD Maastricht, The Netherlands.
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