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Pitzer CR, Paez HG, Ferrandi PJ, Mohamed J, Alway SE. Extracellular vesicles from obese and diabetic mouse plasma alter C2C12 myotube glucose uptake and gene expression. Physiol Rep 2024; 12:e15898. [PMID: 38169108 PMCID: PMC10761623 DOI: 10.14814/phy2.15898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 10/07/2023] [Accepted: 11/20/2023] [Indexed: 01/05/2024] Open
Abstract
Recent studies have indicated a role for circulating extracellular vesicles (EVs) in the pathogenesis of multiple diseases. However, most in vitro studies have used variable and arbitrary doses of EVs rather than interpreting EVs as an existing component of standard skeletal muscle cell culture media. The current study provides an initial investigation into the effects of circulating EVs on the metabolic phenotype of C2C12 myotubes by replacing EVs from fetal bovine serum with circulating EVs from control mice or mice with obesity and type 2 diabetes (OT2D). We report that EVs associated with OT2D decrease 2-NBDG uptake (a proxy measure of glucose uptake) in the insulin-stimulated state compared to controls. OT2D associated EV treatment also significantly decreased myosin heavy chain type 1 (MHCI) mRNA abundance in myotubes but had no effect on mRNA expression of any other myosin heavy chain isoforms. OT2D-associated circulating EVs also significantly increased lipid accumulation within myotubes without altering the expression of a selection of genes important for lipid entry, synthesis, or catabolism. The data indicate that, in a severely diabetic state, circulating EVs may contribute to insulin resistance and alter gene expression in myotubes in a manner consistent with the skeletal muscle phenotype observed in OT2D.
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Affiliation(s)
- Christopher R. Pitzer
- Center for Muscle, Metabolism and Neuropathology, Division of Regenerative and Rehabilitation Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Department of Physiology, College of MedicineThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Integrated Biomedical Sciences Graduate Program, College of Graduate Health SciencesThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Laboratory of Muscle Biology and Sarcopenia, Department of Physical Therapy, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Hector G. Paez
- Center for Muscle, Metabolism and Neuropathology, Division of Regenerative and Rehabilitation Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Department of Physiology, College of MedicineThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Integrated Biomedical Sciences Graduate Program, College of Graduate Health SciencesThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Laboratory of Muscle Biology and Sarcopenia, Department of Physical Therapy, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Peter J. Ferrandi
- Center for Muscle, Metabolism and Neuropathology, Division of Regenerative and Rehabilitation Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Integrated Biomedical Sciences Graduate Program, College of Graduate Health SciencesThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Laboratory of Muscle and Nerve, Department of Diagnostic and Health Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Junaith S. Mohamed
- Center for Muscle, Metabolism and Neuropathology, Division of Regenerative and Rehabilitation Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Laboratory of Muscle and Nerve, Department of Diagnostic and Health Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Tennessee Institute of Regenerative MedicineThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Stephen E. Alway
- Center for Muscle, Metabolism and Neuropathology, Division of Regenerative and Rehabilitation Sciences, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Department of Physiology, College of MedicineThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Laboratory of Muscle Biology and Sarcopenia, Department of Physical Therapy, College of Health ProfessionsThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Tennessee Institute of Regenerative MedicineThe University of Tennessee Health Science CenterMemphisTennesseeUSA
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Benrick A, Pillon NJ, Nilsson E, Lindgren E, Krook A, Ling C, Stener-Victorin E. Electroacupuncture Mimics Exercise-Induced Changes in Skeletal Muscle Gene Expression in Women With Polycystic Ovary Syndrome. J Clin Endocrinol Metab 2020; 105:5813905. [PMID: 32232327 PMCID: PMC7185955 DOI: 10.1210/clinem/dgaa165] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/27/2020] [Indexed: 12/29/2022]
Abstract
CONTEXT Autonomic nervous system activation mediates the increase in whole-body glucose uptake in response to electroacupuncture but the mechanisms are largely unknown. OBJECTIVE To identify the molecular mechanisms underlying electroacupuncture-induced glucose uptake in skeletal muscle in insulin-resistant overweight/obese women with and without polycystic ovary syndrome (PCOS). DESIGN/PARTICIPANTS In a case-control study, skeletal muscle biopsies were collected from 15 women with PCOS and 14 controls before and after electroacupuncture. Gene expression and methylation was analyzed using Illumina BeadChips arrays. RESULTS A single bout of electroacupuncture restores metabolic and transcriptional alterations and induces epigenetic changes in skeletal muscle. Transcriptomic analysis revealed 180 unique genes (q < 0.05) whose expression was changed by electroacupuncture, with 95% of the changes towards a healthier phenotype. We identified DNA methylation changes at 304 unique sites (q < 0.20), and these changes correlated with altered expression of 101 genes (P < 0.05). Among the 50 most upregulated genes in response to electroacupuncture, 38% were also upregulated in response to exercise. We identified a subset of genes that were selectively altered by electroacupuncture in women with PCOS. For example, MSX1 and SRNX1 were decreased in muscle tissue of women with PCOS and were increased by electroacupuncture and exercise. siRNA-mediated silencing of these 2 genes in cultured myotubes decreased glycogen synthesis, supporting a role for these genes in glucose homeostasis. CONCLUSION Our findings provide evidence that electroacupuncture normalizes gene expression in skeletal muscle in a manner similar to acute exercise. Electroacupuncture might therefore be a useful way of assisting those who have difficulties performing exercise.
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Affiliation(s)
- Anna Benrick
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- School of Health Sciences, University of Skövde, Skövde, Sweden
- Correspondence and Reprint Requests: Anna Benrick, University of Gothenburg, Institute of Neuroscience and Physiology, Department of Physiology, Box 423, 405 30 Gothenburg, Sweden. E-mail: ; Elisabet Stener-Victorin- reprint requests, Karolinska Institutet, Department of Physiology and Pharmacology, Biomedicum, B5, Solnavägen 9, 171 77 Stockholm, Sweden. E-mail:
| | - Nicolas J Pillon
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Emma Nilsson
- Epigenetics and Diabetes Unit, Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Scania University Hospital, Malmö, Sweden
| | - Eva Lindgren
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Anna Krook
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Charlotte Ling
- Epigenetics and Diabetes Unit, Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Scania University Hospital, Malmö, Sweden
| | - Elisabet Stener-Victorin
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
- Correspondence and Reprint Requests: Anna Benrick, University of Gothenburg, Institute of Neuroscience and Physiology, Department of Physiology, Box 423, 405 30 Gothenburg, Sweden. E-mail: ; Elisabet Stener-Victorin- reprint requests, Karolinska Institutet, Department of Physiology and Pharmacology, Biomedicum, B5, Solnavägen 9, 171 77 Stockholm, Sweden. E-mail:
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Gaster M. The diabetic phenotype is preserved in myotubes established from type 2 diabetic subjects: a critical appraisal. APMIS 2018; 127:3-26. [DOI: 10.1111/apm.12908] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 11/05/2018] [Indexed: 01/08/2023]
Affiliation(s)
- Michael Gaster
- Laboratory for Molecular Physiology Department of Pathology and Department of Endocrinology Odense University Hospital Odense Denmark
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Myrka AM, Welch KC. Evidence of high transport and phosphorylation capacity for both glucose and fructose in the ruby-throated hummingbird (Archilochus colubris). Comp Biochem Physiol B Biochem Mol Biol 2018; 224:253-261. [DOI: 10.1016/j.cbpb.2017.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/26/2017] [Accepted: 10/31/2017] [Indexed: 02/06/2023]
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Welch KC, Myrka AM, Ali RS, Dick MF. The Metabolic Flexibility of Hovering Vertebrate Nectarivores. Physiology (Bethesda) 2018; 33:127-137. [DOI: 10.1152/physiol.00001.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Foraging hummingbirds and nectar bats oxidize both glucose and fructose from nectar at exceptionally high rates. Rapid sugar flux is made possible by adaptations to digestive, cardiovascular, and metabolic physiology affecting shared and distinct pathways for the processing of each sugar. Still, how these animals partition and regulate the metabolism of each sugar and whether this occurs differently between hummingbirds and bats remain unclear.
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Affiliation(s)
- Kenneth C. Welch
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Center for the Neurobiology of Stress, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Alexander M. Myrka
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Raafay Syed Ali
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Morag F. Dick
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
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Park SY, Yoon JK, Lee SJ, Haam S, Jung J. Prognostic value of preoperative total psoas muscle area on long-term outcome in surgically treated oesophageal cancer patients. Interact Cardiovasc Thorac Surg 2016; 24:13-19. [PMID: 27587471 DOI: 10.1093/icvts/ivw274] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/20/2016] [Accepted: 06/27/2016] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVES Although a decrease in psoas muscle area (PMA) has been reported as a risk factor for survival in several malignancies, there have been few studies regarding its prognostic value in oesophageal cancer. We investigated the prognostic role of PMA and its F-18 fluorodeoxyglucose uptake in patients who had surgically treated oesophageal cancer. METHODS From 2004 to 2013, 131 patients who underwent surgical resection and complete lymph node dissection for oesophageal cancer were retrospectively reviewed. The PMA and mean standardized uptake value (SUVmean) of the psoas muscle were measured at the L3 spine level on preoperative positron emission tomography/computed tomography images. RESULTS The mean age was 63.38 ± 8.47 years and male patients were 125 (95.4%). The pathological stage I, II and III were 38 (29.0%), 41 (31.3%) and 52 (39.7%), respectively. The mean body mass index (BMI), PMA and SUVmean of the psoas muscle were 59.50 ± 10.14, 14.42 ± 4.30 and 1.51 ± 0.27, respectively. Operative mortality occurred in 7 (5.3%) patients. The BMI and PMA were lower in patients with operative mortality than in patients who survived. The median follow-up time was 32.52 months. A multivariate analysis revealed that PMA was an adverse risk factor for overall survival (OS) (hazard ratio, HR = 0.930; P= 0.004), whereas BMI was related to OS. The 3-year OS rates were 64.9% in high-PMA (≥15.8) patients; however, it was only 37.1% in low-PMA (less than 15.8) patients (P= 0.002). Akaike information criterion was the lowest by including PMA in the multivariate model. CONCLUSIONS Decreased PMA was an adverse significant prognostic factor for OS in patients with oesophageal cancer.
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Affiliation(s)
- Seong Yong Park
- Department of Thoracic and Cardiovascular Surgery, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Joon-Kee Yoon
- Department of Nuclear Medicine and Molecular Imaging, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Su Jin Lee
- Department of Nuclear Medicine and Molecular Imaging, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Seokjin Haam
- Department of Thoracic and Cardiovascular Surgery, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Joonho Jung
- Department of Thoracic and Cardiovascular Surgery, Ajou University School of Medicine, Suwon, Republic of Korea
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Bradley H, Shaw CS, Bendtsen C, Worthington PL, Wilson OJ, Strauss JA, Wallis GA, Turner AM, Wagenmakers AJM. Visualization and quantitation of GLUT4 translocation in human skeletal muscle following glucose ingestion and exercise. Physiol Rep 2015; 3:3/5/e12375. [PMID: 25969463 PMCID: PMC4463815 DOI: 10.14814/phy2.12375] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Insulin- and contraction-stimulated increases in glucose uptake into skeletal muscle occur in part as a result of the translocation of glucose transporter 4 (GLUT4) from intracellular stores to the plasma membrane (PM). This study aimed to use immunofluorescence microscopy in human skeletal muscle to quantify GLUT4 redistribution from intracellular stores to the PM in response to glucose feeding and exercise. Percutaneous muscle biopsy samples were taken from the m. vastus lateralis of ten insulin-sensitive men in the basal state and following 30 min of cycling exercise (65% VO2 max). Muscle biopsy samples were also taken from a second cohort of ten age-, BMI- and VO2 max-matched insulin-sensitive men in the basal state and 30 and 60 min following glucose feeding (75 g glucose). GLUT4 and dystrophin colocalization, measured using the Pearson's correlation coefficient, was increased following 30 min of cycling exercise (baseline r = 0.47 ± 0.01; post exercise r = 0.58 ± 0.02; P < 0.001) and 30 min after glucose ingestion (baseline r = 0.42 ± 0.02; 30 min r = 0.46 ± 0.02; P < 0.05). Large and small GLUT4 clusters were partially depleted following 30 min cycling exercise, but not 30 min after glucose feeding. This study has, for the first time, used immunofluorescence microscopy in human skeletal muscle to quantify increases in GLUT4 and dystrophin colocalization and depletion of GLUT4 from large and smaller clusters as evidence of net GLUT4 translocation to the PM.
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Affiliation(s)
- Helen Bradley
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Christopher S Shaw
- School of Exercise and Nutrition Sciences, Deakin University, Geelong, Vic., Australia
| | - Claus Bendtsen
- Computational Biology, Discovery Sciences, AstraZeneca R&D, Cambridge, UK
| | - Philip L Worthington
- Computational Biology, Discovery Sciences, AstraZeneca R&D, Alderley Park Macclesfield, UK
| | - Oliver J Wilson
- Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
| | - Juliette A Strauss
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Gareth A Wallis
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Alice M Turner
- School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK Heart of England NHS Foundation Trust, Bordesley Green East Birmingham, UK
| | - Anton J M Wagenmakers
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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Delayed muscle development in small pig fetuses around birth cannot be rectified by maternal early feed restriction and subsequent overfeeding during gestation. Animal 2015; 9:1996-2005. [DOI: 10.1017/s1751731115001202] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Morato PN, Lollo PCB, Moura CS, Batista TM, Camargo RL, Carneiro EM, Amaya-Farfan J. Whey protein hydrolysate increases translocation of GLUT-4 to the plasma membrane independent of insulin in wistar rats. PLoS One 2013; 8:e71134. [PMID: 24023607 PMCID: PMC3758293 DOI: 10.1371/journal.pone.0071134] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/26/2013] [Indexed: 11/22/2022] Open
Abstract
Whey protein (WP) and whey protein hydrolysate (WPH) have the recognized capacity to increase glycogen stores. The objective of this study was to verify if consuming WP and WPH could also increase the concentration of the glucose transporters GLUT-1 and GLUT-4 in the plasma membrane (PM) of the muscle cells of sedentary and exercised animals. Forty-eight Wistar rats were divided into 6 groups (n = 8 per group), were treated and fed with experimental diets for 9 days as follows: a) control casein (CAS); b) WP; c) WPH; d) CAS exercised; e) WP exercised; and f) WPH exercised. After the experimental period, the animals were sacrificed, muscle GLUT-1 and GLUT-4, p85, Akt and phosphorylated Akt were analyzed by western blotting, and the glycogen, blood amino acids, insulin levels and biochemical health indicators were analyzed using standard methods. Consumption of WPH significantly increased the concentrations of GLUT-4 in the PM and glycogen, whereas the GLUT-1 and insulin levels and the health indicators showed no alterations. The physical exercise associated with consumption of WPH had favorable effects on glucose transport into muscle. These results should encourage new studies dealing with the potential of both WP and WPH for the treatment or prevention of type II diabetes, a disease in which there is reduced translocation of GLUT-4 to the plasma membrane.
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Affiliation(s)
- Priscila Neder Morato
- University of Campinas (UNICAMP), Faculty of Food Engineering (FEA), Campinas, São Paulo, Brazil
- * E-mail:
| | | | - Carolina Soares Moura
- University of Campinas (UNICAMP), Faculty of Food Engineering (FEA), Campinas, São Paulo, Brazil
| | - Thiago Martins Batista
- University of Campinas (UNICAMP), Institute of Biology (IB), Campinas, São Paulo, Brazil
| | | | | | - Jaime Amaya-Farfan
- University of Campinas (UNICAMP), Faculty of Food Engineering (FEA), Campinas, São Paulo, Brazil
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Santos JM, Benite-Ribeiro SA, Queiroz G, Duarte JA. The effect of age on glucose uptake and GLUT1 and GLUT4 expression in rat skeletal muscle. Cell Biochem Funct 2011; 30:191-7. [DOI: 10.1002/cbf.1834] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Revised: 10/10/2011] [Accepted: 10/12/2011] [Indexed: 01/07/2023]
Affiliation(s)
| | | | - G. Queiroz
- Laboratory of Pharmacology, Department of Drugs Sciences, REQUIMTE, Faculty of Pharmacy; University of Porto; Portugal
| | - J. A. Duarte
- CIAFEL, Faculty of Sport; University of Porto; Portugal
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Fedrigo O, Pfefferle AD, Babbitt CC, Haygood R, Wall CE, Wray GA. A potential role for glucose transporters in the evolution of human brain size. BRAIN, BEHAVIOR AND EVOLUTION 2011; 78:315-26. [PMID: 21986508 DOI: 10.1159/000329852] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 06/05/2011] [Indexed: 12/12/2022]
Abstract
Differences in cognitive abilities and the relatively large brain are among the most striking differences between humans and their closest primate relatives. The energy trade-off hypothesis predicts that a major shift in energy allocation among tissues occurred during human origins in order to support the remarkable expansion of a metabolically expensive brain. However, the molecular basis of this adaptive scenario is unknown. Two glucose transporters (SLC2A1 and SLC2A4) are promising candidates and present intriguing mutations in humans, resulting, respectively, in microcephaly and disruptions in whole-body glucose homeostasis. We compared SLC2A1 and SLC2A4 expression between humans, chimpanzees and macaques, and found compensatory and biologically significant expression changes on the human lineage within cerebral cortex and skeletal muscle, consistent with mediating an energy trade-off. We also show that these two genes are likely to have undergone adaptation and participated in the development and maintenance of a larger brain in the human lineage by modulating brain and skeletal muscle energy allocation. We found that these two genes show human-specific signatures of positive selection on known regulatory elements within their 5'-untranslated region, suggesting an adaptation of their regulation during human origins. This study represents the first case where adaptive, functional and genetic lines of evidence implicate specific genes in the evolution of human brain size.
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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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John SA, Ottolia M, Weiss JN, Ribalet B. Dynamic modulation of intracellular glucose imaged in single cells using a FRET-based glucose nanosensor. Pflugers Arch 2007; 456:307-22. [PMID: 18071748 DOI: 10.1007/s00424-007-0395-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 11/07/2007] [Indexed: 10/22/2022]
Abstract
To study intracellular glucose homeostasis, the glucose nanosensor FLIPglu-600 microM, which undergoes changes in fluorescence resonance energy transfer (FRET) upon interaction with glucose, was expressed in four mammalian cell lines: COS-7, CHO, HEK293, and C2C12. Upon addition of extracellular glucose, the intracellular FRET ratio decreased rapidly as intracellular glucose increased. The kinetics were fast (tau=5 to 15 s) in COS and C2C12 cells and slow (tau=20 to 40 s) in HEK and CHO cells. Upon removal of extracellular glucose, the FRET ratio returned to its initial value at similar rates (tau=15 to 40 s) in all cell types. In all cell types, the glucose uptake FRET signal was blocked by the glucose transporter (GLUTx) inhibitor cytochalasin B and was not affected by the Na/glucose transporter inhibitor phlorizin. Glucose clearance was inhibited by the glycolytic inhibitor iodoacetate. Using beta-escin to permeabilize the cell, we found that the glucose gradient across the membrane was strongly dependent on the rates of glucose uptake versus glucose clearance. With 10 mM extracellular glucose and a high rate of glucose clearance, intracellular glucose level fell below 100 muM when glucose uptake rate was low, whereas it exceeded 0.5 mM when glucose uptake was high. Cells cultured in high glucose maintained lower basal intracellular glucose levels than cells cultured in low glucose, attributed to "reciprocal regulation" of glycolysis and gluconeogenesis. Basal glucose level also increased with elevated temperatures. Experiments performed with C2C12 cells demonstrated a shift from fast glucose uptake to slow glucose uptake in the absence of insulin during differentiation.
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Affiliation(s)
- Scott A John
- UCLA Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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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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Handberg A, Levin K, Højlund K, Beck-Nielsen H. Identification of the oxidized low-density lipoprotein scavenger receptor CD36 in plasma: a novel marker of insulin resistance. Circulation 2006; 114:1169-76. [PMID: 16952981 DOI: 10.1161/circulationaha.106.626135] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Macrophage CD36 scavenges oxidized low-density lipoprotein, leading to foam cell formation, and appears to be a key proatherogenic molecule. Increased expression of CD36 has been attributed to hyperglycemia and to defective macrophage insulin signaling in insulin resistance. Premature atherosclerosis is the major cause of morbidity and mortality in type 2 diabetes. Here, we report the identification of a soluble form of CD36 (sCD36) in plasma and hypothesize that sCD36 would be elevated in patients with type 2 diabetes and insulin resistance. METHODS AND RESULTS sCD36 in plasma was demonstrated by immunopurification and Western blotting. We established ELISA assays to determine sCD36 in plasma and measured sCD36 in obese type 2 diabetic patients, obese nondiabetic relatives, and obese and lean control subjects. sCD36 was markedly elevated in type 2 diabetic patients compared with both lean (5-fold) and obese (2- to 3-fold) control subjects. There was a strong, inverse correlation between sCD36 and insulin-stimulated glucose disposal and a direct correlation with fasting plasma glucose, fasting insulin, and body mass index. CONCLUSIONS Our study demonstrates sCD36 in plasma for the first time. sCD36 is highly related to risk factors of accelerated atherosclerosis in type 2 diabetes such as insulin resistance and glycemic control, and we propose that sCD36 might represent a marker of the metabolic syndrome and a potential surrogate marker of atherosclerosis.
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Affiliation(s)
- Aase Handberg
- Department of Clinical Biochemistry, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark.
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Ozden S, Mouly V, Prevost MC, Gessain A, Butler-Browne G, Ceccaldi PE. Muscle wasting induced by HTLV-1 tax-1 protein: an in vitro and in vivo study. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 167:1609-19. [PMID: 16314474 PMCID: PMC1613204 DOI: 10.1016/s0002-9440(10)61245-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Besides tropical spastic paraparesis/human T-cell leukemia virus type-1 (HTLV-1)-associated myelopathy, the human retrovirus HTLV-1 causes inflammatory disorders such as myositis. Although the pathogenesis of HTLV-1-associated myositis is primarily unknown, a direct effect of cytokines or viral proteins in myocytotoxicity is suspected. We have developed an in vitro cell culture model to study the interactions between primary human muscle cells and HTLV-1 chronically infected cells. When HTLV-1-infected cell lines were added to differentiated muscle cultures, cytopathic changes such as fiber shrinking were observed as early as 1 day after contact. This was accompanied by alterations in desmin and vimentin organization, occurring in the absence of muscle cell infection but with Tax-1 present in myotubes. Cytopathic changes were also observed when infected culture supernatants were added to the muscle cells. Fiber atrophy and cytoskeletal disorganization were confirmed in muscle biopsies from two HTLV-1-infected patients with myositis. Transduction of cultured muscle cells with a lentiviral vector containing the HTLV-1 Tax gene reproduced such effects in vitro. The present data indicate that the myocytotoxicity that is observed in HTLV-1-associated myopathies can be due to a direct effect of the Tax-1 protein expressed in infected inflammatory cells, in the absence of muscle cell infection.
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Affiliation(s)
- Simona Ozden
- Unité d'Epidémiologie et Physiopathologie des Virus Oncogènes, Département Ecosystèmes et Epidémiologie des Maladies Infectieuses, Institut Pasteur, Paris, France
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Corbould A, Kim YB, Youngren JF, Pender C, Kahn BB, Lee A, Dunaif A. Insulin resistance in the skeletal muscle of women with PCOS involves intrinsic and acquired defects in insulin signaling. Am J Physiol Endocrinol Metab 2005; 288:E1047-54. [PMID: 15613682 DOI: 10.1152/ajpendo.00361.2004] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin resistance in polycystic ovary syndrome (PCOS) is due to a postbinding defect in signaling that persists in cultured skin fibroblasts and is associated with constitutive serine phosphorylation of the insulin receptor (IR). Cultured skeletal muscle from obese women with PCOS and age- and body mass index-matched control women (n = 10/group) was studied to determine whether signaling defects observed in this tissue in vivo were intrinsic or acquired. Basal and insulin-stimulated glucose transport and GLUT1 abundance were significantly increased in cultured myotubes from women with PCOS. Neither IR beta-subunit abundance and tyrosine autophosphorylation nor insulin receptor substrate (IRS)-1-associated phosphatidylinositol (PI) 3-kinase activity differed in the two groups. However, IRS-1 protein abundance was significantly increased in PCOS, resulting in significantly decreased PI 3-kinase activity when normalized for IRS-1. Phosphorylation of IRS-1 on Ser312, a key regulatory site, was significantly increased in PCOS, which may have contributed to this signaling defect. Insulin signaling via IRS-2 was also decreased in myotubes from women with PCOS. In summary, decreased insulin-stimulated glucose uptake in PCOS skeletal muscle in vivo is an acquired defect. Nevertheless, there are intrinsic abnormalities in glucose transport and insulin signaling in myotubes from affected women, including increased phosphorylation of IRS-1 Ser312, that may confer increased susceptibility to insulin resistance-inducing factors in the in vivo environment. These abnormalities differ from those reported in other insulin resistant states consistent with the hypothesis that PCOS is a genetically unique disorder conferring an increased risk for type 2 diabetes.
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Affiliation(s)
- Anne Corbould
- Division of Women's Health, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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18
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Berggren JR, Tanner CJ, Koves TR, Muoio DM, Houmard JA. Glucose Uptake in Muscle Cell Cultures from Endurance-Trained Men. Med Sci Sports Exerc 2005; 37:579-84. [PMID: 15809555 DOI: 10.1249/01.mss.0000158180.11224.e8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To examine noninsulin- (basal) and insulin-mediated glucose uptake in human skeletal muscle cells from endurance-trained and sedentary individuals. METHODS Muscle biopsies (vastus lateralis) were obtained from competitive, endurance-trained athletes (N=12; VO2peak 64.9+/-2.3 mL.kg-1.min-1) and their sedentary counterparts (N=8; VO2peak 51.8+/-2.2 mL.kg-1.min-1), and isolated satellite cells allowed to proceed to myotubes. RESULTS The myotubes exhibited a dose response for glucose uptake with increasing insulin concentrations; maximal glucose uptake was approximately 1.5-fold over basal. In relation to exercise training status, basal glucose uptake was significantly (P<0.05) elevated by approximately 75% in the endurance-trained versus sedentary men (20.1+/-2.1 vs 11.9+/-1.9 pmol.mg protein-1.min-1, respectively). This difference persisted at insulin concentrations of 10 and 1000 etaM, although the relative increase in insulin-mediated glucose uptake (fold increase over basal) did not differ between the sedentary and endurance-trained cells. CONCLUSIONS These data suggest that cultured skeletal muscle cells from endurance-trained athletes may differ in respect to basal glucose uptake.
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Affiliation(s)
- Jason R Berggren
- Human Performance Laboratory, Department of Exercise & Sport Science, and Diabetes/Obesity Center, East Carolina University, Greenville, NC 27858, USA.
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19
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Baker EL, Dennis RG, Larkin LM. Glucose transporter content and glucose uptake in skeletal muscle constructs engineered in vitro. In Vitro Cell Dev Biol Anim 2005; 39:434-9. [PMID: 14741039 DOI: 10.1290/1543-706x(2003)039<0434:gtcagu>2.0.co;2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Engineered muscle may eventually be used as a treatment option for patients suffering from loss of muscle function. The metabolic and contractile function of engineered muscle has not been well described; therefore, the purpose of this experiment was to study glucose transporter content and glucose uptake in engineered skeletal muscle constructs called myooids. Glucose uptake by way of 2-deoxyglucose and GLUT-1 and GLUT-4 transporter protein content was measured in basal and insulin-stimulated myooids that were engineered from soleus muscles of female Sprague-Dawley rats. There was a significant increase in the basal 2-deoxyglucose uptake of myooids compared with adult control (fivefold), contraction-stimulated (3.4-fold), and insulin-stimulated (threefold) soleus muscles (P = 0.0001, 0.0001, and 0.0001, respectively). In addition, there was a significant increase in the insulin-stimulated 2-deoxyglucose uptake of myooids compared with adult control soleus muscles in basal conditions (6.5-fold) and adult contraction-stimulated (4.5-fold) and insulin- stimulated (3.9-fold) soleus muscles (P = 0.0001, 0.0001, and 0.0001, respectively). There was a significant 30% increase in insulin-stimulated compared with basal 2-deoxyglucose uptake in the myooids. The myooid GLUT-1 protein content was 820% of the adult control soleus muscle, whereas the GLUT-4 protein content was 130% of the control soleus muscle. Myooid GLUT-1 protein content was 6.3-fold greater than GLUT-4 protein content, suggesting that the glucose transport of the engineered myooids is similar in several respects to that observed in both fetal and denervated skeletal muscle tissue.
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Affiliation(s)
- Erin L Baker
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2007, USA
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20
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Anderson MS, Thamotharan M, Kao D, Devaskar SU, Qiao L, Friedman JE, Hay WW. Effects of acute hyperinsulinemia on insulin signal transduction and glucose transporters in ovine fetal skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2004; 288:R473-81. [PMID: 15539611 DOI: 10.1152/ajpregu.00405.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To test the effects of acute fetal hyperinsulinemia on the pattern and time course of insulin signaling in ovine fetal skeletal muscle, we measured selected signal transduction proteins in the mitogenic, protein synthetic, and metabolic pathways in the skeletal muscle of normally growing fetal sheep in utero. In experiment 1, 4-h hyperinsulinemic-euglycemic clamps were conducted in anesthetized twin fetuses to produce selective fetal hyperinsulinemia-euglycemia in one twin and euinsulinemia-euglycemia in the other. Serial skeletal muscle biopsies were taken from each fetus during the clamp and assayed by Western blot for selected insulin signal transduction proteins. Tyrosine phosphorylation of the insulin receptor, insulin receptor substrate-1, and the p85 subunit of phosphatidylinositol 3-kinase doubled at 30 min and gradually returned to control values by 240 min. Phosphorylation of extracellular signal-regulated kinase 1,2 was increased fivefold through 120 min of insulin infusion and decreased to control concentration by 240 min. Protein kinase B phosphorylation doubled at 30 min and remained elevated throughout the study. Phosphorylation of p70 S6K increased fourfold at 30, 60, and 120 min. In the second experiment, a separate group of nonanesthetized singleton fetuses was clamped to intermediate and high hyperinsulinemic-euglycemic conditions for 1 h. GLUT4 increased fourfold in the plasma membrane at 1 h, and hindlimb glucose uptake increased significantly at the higher insulin concentration. These data demonstrate that an acute increase in fetal plasma insulin concentration stimulates a unique pattern of insulin signal transduction proteins in intact skeletal muscle, thereby increasing pathways for mRNA translation, glucose transport, and cell growth.
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Affiliation(s)
- Marianne S Anderson
- Pediatrics/Neonatology, University of Colorado Health Sciences Center, Denver, Colorado, USA.
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21
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Kamel AF, Norgren S, Strigård K, Thörne A, Fakhrai-Rad H, Galli J, Marcus C. Age-dependent regulation of lipogenesis in human and rat adipocytes. J Clin Endocrinol Metab 2004; 89:4601-6. [PMID: 15356069 DOI: 10.1210/jc.2003-030994] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The regulation of adipocyte metabolism is of importance for adipose tissue growth and therefore also for the development of obesity. This study was designed to investigate the regulation of basal and insulin-induced lipogenesis, glucose transport, and glucose transporter protein expression in human and rat adipocytes from different age groups. The study included 21 infants, 21 children, nine adults, and 80 male weaned and 20 male adult Fischer rats. The lipogenesis experiments were performed under conditions at which glucose transport is rate limiting. Basal lipogenesis was approximately three times higher in infants and children than in adults, whereas insulin-induced lipogenesis was two times higher in infants than in children and adults. In rats, basal lipogenesis, insulin-induced lipogenesis, and insulin sensitivity were two times higher in weaned than in adult animals. Moreover, basal and insulin-induced glucose transport were two times higher in weaned than in adult rats. No differences were detected in GLUT1 or GLUT4 content between any of the age groups in human or in rat adipocytes. In conclusion, basal and insulin-stimulated lipogenesis are increased in adipocytes early in life. This may promote adipose tissue growth in early age. The data indicate that age-dependent variation in basal and insulin-stimulated lipogenesis is differently regulated.
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Affiliation(s)
- Ashraf F Kamel
- Department of Pediatrics, National Childhood Obesity Centre, Children's Hospital, Huddinge University Hospital, Karolinska Institute, S-141 86 Huddinge, Sweden
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22
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Gaster M, Handberg A, Schürmann A, Joost HG, Beck-Nielsen H, Schrøder HD. GLUT11, but not GLUT8 or GLUT12, is expressed in human skeletal muscle in a fibre type-specific pattern. Pflugers Arch 2003; 448:105-13. [PMID: 14704796 DOI: 10.1007/s00424-003-1219-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Revised: 10/24/2003] [Accepted: 11/20/2003] [Indexed: 12/22/2022]
Abstract
Nine novel sugar transporter-like proteins have been discovered in the past 5 years. The mRNA for three of these, the glucose transporters (GLUT) GLUT8, GLUT11 and GLUT12, have been detected in human skeletal muscle. In the present study, we examined the pattern of expression and localization of the GLUT isoforms 8, 11 and 12 in human skeletal muscle using an immunohistochemical approach. Biopsies of human skeletal muscle from sedentary or trained healthy adults, from fetal muscle (24 weeks of gestation), from obese type-2 diabetic subjects, and from patients suffering from polymyositis or amyotrophic lateral sclerosis (ALS) were studied. GLUT8 and 12 immunoreactivity was below detection level in both developing and adult muscle fibres. GLUT11 immunoreactivity, however, was present in slow-twitch muscle fibres, but not in fast twitch fibres. Since, in contrast, GLUT4 was expressed in all investigated muscle fibres, the pattern of expression of GLUT11 differs from that of GLUT4, suggesting a specialized function for GLUT11 with a regulation independent from that of GLUT4. Obesity, type-2 diabetes, training, conditions of de- and reinnervation (ALS) and regeneration (polymyositis) failed to induce GLUT8 or -12 expression. Likewise, the fibre type-dependent pattern of GLUT11 immunoreactivity was unaltered. However, some slow muscle fibres lose their GLUT11 immunoreactivity under regeneration. Our results indicate that GLUT11 immunoreactivity, in contrast to that of GLUT4, is expressed exclusively in slow-twitch muscle fibres and is unaffected by physiological and pathophysiological conditions except in primary myopathy. GLUT8 and GLUT12 do not appear to be of importance in human muscle under physiological and pathophysiological conditions.
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Affiliation(s)
- M Gaster
- Department of Endocrinology, Odense University Hospital, 5000 Odense, Denmark.
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23
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Nevzorova J, Bengtsson T, Evans BA, Summers RJ. Characterization of the beta-adrenoceptor subtype involved in mediation of glucose transport in L6 cells. Br J Pharmacol 2002; 137:9-18. [PMID: 12183326 PMCID: PMC1573471 DOI: 10.1038/sj.bjp.0704845] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The receptor that mediates the increase in glucose transport (GT) in response to beta-adrenoceptor (beta-AR) agonists was characterized in the rat skeletal muscle cell line L6, using the 2-deoxy-[(3)H]-D-glucose assay. 2. The beta(3)-AR agonist BRL37344 (pEC(50) = 6.89 +/- 0.21), the beta-AR agonist isoprenaline (pEC(50) = 8.99 +/ -0.24) and the beta(2)-AR agonist zinterol (pEC(50) = 9.74 +/- 0.15) increased GT as did insulin (pEC(50) = 6.93 +/- 0.15). The highly selective beta(3)-AR agonist CL316243 only weakly stimulated GT. 3. The pK(B) values calculated from the shift of the pEC(50) values of the agonists in the presence of the beta(1)-AR selective antagonist CGP 20712A or the beta(3)-AR selective antagonist SR 59230A were not indicative of activation of beta(1)- or beta(3)-ARs. Only (-)-propranolol and the beta(2)-AR selective antagonist ICI 118551 caused marked rightward shifts of CR curves to isoprenaline (pK(B) = 10.2 +/- 0.2 and 9.6 +/- 0.3), zinterol (pK(B) = 9.0 +/- 0.1 and 9.4 +/- 0.3) and BRL 37344 (pK(B) = 9.4 +/- 0.3 and 8.4 +/- .2), indicating participation of beta(2)-ARs. 4. The pharmacological analysis was supported by reverse transcription and polymerase chain reaction analysis of L6 mRNA, which showed high levels of expression of beta(2)-AR but not beta(1)- or beta(3)-AR in these cells. 5. Forskolin and dibutyryl cyclic AMP produced negligible increases in GT while the phosphatidylinositol-3 kinase inhibitor, wortmannin, significantly decreased both insulin- and zinterol-stimulated GT, suggesting a possible interaction between the insulin and beta(2)-AR pathways. 6. This study demonstrates that beta(2)-ARs mediate the increase in GT in L6 cells to beta-AR agonists, including the beta(3)-AR selective agonist BRL 37344. This effect does not appear to be directly related to increases in cyclic AMP but requires P13K.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Adrenergic beta-Antagonists/pharmacology
- Androstadienes/pharmacology
- Animals
- Biological Transport
- Bucladesine/pharmacology
- Cells, Cultured
- Colforsin/pharmacology
- Dose-Response Relationship, Drug
- Glucose/metabolism
- Insulin/pharmacology
- Insulin/physiology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- RNA, Messenger/metabolism
- Rats
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Wortmannin
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Affiliation(s)
- Julia Nevzorova
- Department of Pharmacology, PO Box 13E, Monash University, Victoria 3800, Australia
| | - Tore Bengtsson
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bronwyn A Evans
- Department of Pharmacology, PO Box 13E, Monash University, Victoria 3800, Australia
| | - Roger J Summers
- Department of Pharmacology, PO Box 13E, Monash University, Victoria 3800, Australia
- Author for correspondence:
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24
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Gaster M, Vach W, Beck-Nielsen H, Schrøder HD. GLUT4 expression at the plasma membrane is related to fibre volume in human skeletal muscle fibres. APMIS 2002; 110:611-9. [PMID: 12529013 DOI: 10.1034/j.1600-0463.2002.1100903.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this study we examined the relationship between GLUT4 expression at the plasma membrane and muscle fibre size in fibre-typed human muscle fibres by immunocytochemistry and morphometry in order to gain further insight into the regulation of GLUT4 expression. At the site of the plasma membrane, GLUT4 was more abundantly expressed in slow as compared to fast fibres at the same fibre diameter (p < 0.01) and the GLUT4 expression increased with increasing fibre radius independently of fibre type (p < 0.01). The GLUT4 density at the surface of slow fibres of both diabetic and obese was reduced compared to control subjects at the same diameter (p < 0.001). Fast fibres in obese and type 2 diabetic subjects expressed a fibre-volume-dependent GLUT4 expression (p < 0.001), while this did not reach significance in slow fibres (obese p = 0.18 and diabetic p = 0.06). Our results show that increasing fibre volume is associated with increasing GLUT4 expression in both slow and fast fibres. Based on the possible dependency of GLUT4 expression on volume, we hypothesize that the reduced GLUT4 expression in obesity and type 2 diabetes may partly be compensated for by physical activity.
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MESH Headings
- Adult
- Biological Transport
- Cell Membrane/metabolism
- Cell Size
- Diabetes Mellitus, Type 2/metabolism
- Glucose Transporter Type 4
- Humans
- Immunohistochemistry
- Male
- Mathematics
- Middle Aged
- Monosaccharide Transport Proteins/analysis
- Monosaccharide Transport Proteins/biosynthesis
- Monosaccharide Transport Proteins/metabolism
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Fast-Twitch/ultrastructure
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/ultrastructure
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/ultrastructure
- Muscle Proteins
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/ultrastructure
- Myosins/analysis
- Obesity/metabolism
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Affiliation(s)
- M Gaster
- Dept of Pathology, Odense University Hospital, Denmark.
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25
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Gaster M, Franch J, Staehr P, Beck-Nielsen H, Smith T, Schrøder HD. Induction of GLUT-1 protein in adult human skeletal muscle fibers. Am J Physiol Endocrinol Metab 2000; 279:E1191-5. [PMID: 11052976 DOI: 10.1152/ajpendo.2000.279.5.e1191] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prompted by our recent observations that GLUT-1 is expressed in fetal muscles, but not in adult muscle fibers, we decided to investigate whether GLUT-1 expression could be reactivated. We studied different stimuli concerning their ability to induce GLUT-1 expression in mature human skeletal muscle fibers. Metabolic stress (obesity, non-insulin-dependent diabetes mellitus), contractile activity (training), and conditions of de- and reinnervation (amyotrophic lateral sclerosis) could not induce GLUT-1 expression in human muscle fibers. However, regenerating muscle fibers in polymyositis expressed GLUT-1. In contrast to GLUT-1, GLUT-4 was expressed in all investigated muscle fibers. Although the significance of GLUT-1 in adult human muscle fibers appears limited, GLUT-1 may be of importance for the glucose supplies in immature and regenerating muscle.
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Affiliation(s)
- M Gaster
- Department of Pathology, Odense University Hospital, DK-5000 Odense, Denmark
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