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Mezincescu AM, Rudd A, Cheyne L, Horgan G, Philip S, Cameron D, van Loon L, Whitfield P, Gribbin R, Hu MK, Delibegovic M, Fielding B, Lobley G, Thies F, Newby DE, Gray S, Henning A, Dawson D. Comparison of intramyocellular lipid metabolism in patients with diabetes and male athletes. Nat Commun 2024; 15:3690. [PMID: 38750012 PMCID: PMC11096352 DOI: 10.1038/s41467-024-47843-y] [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: 03/24/2023] [Accepted: 04/05/2024] [Indexed: 05/18/2024] Open
Abstract
Despite opposing insulin sensitivity and cardiometabolic risk, both athletes and patients with type 2 diabetes have increased skeletal myocyte fat storage: the so-called "athlete's paradox". In a parallel non-randomised, non-blinded trial (NCT03065140), we characterised and compared the skeletal myocyte lipid signature of 29 male endurance athletes and 30 patients with diabetes after undergoing deconditioning or endurance training respectively. The primary outcomes were to assess intramyocellular lipid storage of the vastus lateralis in both cohorts and the secondary outcomes were to examine saturated and unsaturated intramyocellular lipid pool turnover. We show that athletes have higher intramyocellular fat saturation with very high palmitate kinetics, which is attenuated by deconditioning. In contrast, type 2 diabetes patients have higher unsaturated intramyocellular fat and blunted palmitate and linoleate kinetics but after endurance training, all were realigned with those of deconditioned athletes. Improved basal insulin sensitivity was further associated with better serum cholesterol/triglycerides, glycaemic control, physical performance, enhanced post insulin receptor pathway signalling and metabolic sensing. We conclude that insulin-resistant, maladapted intramyocellular lipid storage and turnover in patients with type 2 diabetes show reversibility after endurance training through increased contributions of the saturated intramyocellular fatty acid pools. Clinical Trial Registration: NCT03065140: Muscle Fat Compartments and Turnover as Determinant of Insulin Sensitivity (MISTY).
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Affiliation(s)
- Alice M Mezincescu
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Amelia Rudd
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Lesley Cheyne
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | | | - Sam Philip
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Donnie Cameron
- C.J. Gorter MRI Center, Leiden University Medical Center, Leiden, The Netherlands
| | - Luc van Loon
- University of Maastricht, Maastricht, The Netherlands
| | | | | | - May Khei Hu
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Mirela Delibegovic
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | | | - Gerald Lobley
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Frank Thies
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - David E Newby
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | | | | | - Dana Dawson
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK.
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Alqallaf J, Orange ST, Matu J, Griffiths A, Johnson K, Stavropoulos-Kalinoglou A, Holliday A, Wilson O. The Effect of High-Fat Diet on Intramyocellular Lipid Content in Healthy Adults: A Systematic Review, Meta-Analysis, and Meta-Regression. J Nutr 2024; 154:1087-1100. [PMID: 38417551 PMCID: PMC11007750 DOI: 10.1016/j.tjnut.2024.02.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/01/2024] Open
Abstract
Fatty acids are stored within the muscle as intramyocellular lipids (IMCL). Some, but not all, studies indicate that following a high-fat diet (HFD), IMCL may accumulate and affect insulin sensitivity. This systematic review and meta-analysis aimed to quantify the effects of an HFD on IMCL. It also explored the potential modifying effects of HFD fat content and duration, IMCL measurement technique, physical activity status, and the associations of IMCL with insulin sensitivity. Five databases were systematically searched for studies that examined the effect of ≥3 d of HFD (>35% daily energy intake from fat) on IMCL content in healthy individuals. Meta-regressions were used to investigate associations of the HFD total fat content, duration, physical activity status, IMCL measurement technique, and insulin sensitivity with IMCL responses. Changes in IMCL content and insulin sensitivity (assessed by hyperinsulinemic-euglycemic clamp) are presented as standardized mean difference (SMD) using a random effects model with 95% confidence intervals (95% CIs). Nineteen studies were included in the systematic review and 16 in the meta-analysis. IMCL content increased following HFD (SMD = 0.63; 95% CI: 0.31, 0.94, P = 0.001). IMCL accumulation was not influenced by total fat content (P = 0.832) or duration (P = 0.844) of HFD, physical activity status (P = 0.192), or by the IMCL measurement technique (P > 0.05). Insulin sensitivity decreased following HFD (SMD = -0.34; 95% CI: -0.52, -0.16; P = 0.003), but this was not related to the increase in IMCL content following HFD (P = 0.233). Consumption of an HFD (>35% daily energy intake from fat) for ≥3 d significantly increases IMCL content in healthy individuals regardless of HFD total fat content and duration of physical activity status. All IMCL measurement techniques detected the increased IMCL content following HFD. The dissociation between changes in IMCL and insulin sensitivity suggests that other factors may drive HFD-induced impairments in insulin sensitivity in healthy individuals. This trial was registered at PROSPERO as CRD42021257984.
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Affiliation(s)
- Jasem Alqallaf
- Carnegie School of Sport, Leeds Beckett University, United Kingdom
| | - Samuel T Orange
- School of Biomedical, Nutritional, and Sport Sciences, Faculty of Medical Sciences, Newcastle University, United Kingdom; Newcastle University Centre for Cancer, Newcastle University, United Kingdom
| | - Jamie Matu
- School of Health, Leeds Beckett University, United Kingdom
| | - Alex Griffiths
- School of Health, Leeds Beckett University, United Kingdom
| | - Kelsie Johnson
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, United Kingdom
| | | | - Adrian Holliday
- School of Biomedical, Nutritional, and Sport Sciences, Faculty of Medical Sciences, Newcastle University, United Kingdom
| | - Oliver Wilson
- Carnegie School of Sport, Leeds Beckett University, United Kingdom.
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Irshad Z, Lund J, Sillars A, Løvsletten NG, Gharanei S, Salt IP, Freeman DJ, Gill JMR, Thoresen GH, Rustan AC, Zammit VA. The roles of DGAT1 and DGAT2 in human myotubes are dependent on donor patho-physiological background. FASEB J 2023; 37:e23209. [PMID: 37779421 PMCID: PMC10947296 DOI: 10.1096/fj.202300960rr] [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: 05/11/2023] [Revised: 09/01/2023] [Accepted: 09/06/2023] [Indexed: 10/03/2023]
Abstract
The roles of DGAT1 and DGAT2 in lipid metabolism and insulin responsiveness of human skeletal muscle were studied using cryosections and myotubes prepared from muscle biopsies from control, athlete, and impaired glucose regulation (IGR) cohorts of men. The previously observed increases in intramuscular triacylglycerol (IMTG) in athletes and IGR were shown to be related to an increase in lipid droplet (LD) area in type I fibers in athletes but, conversely, in type II fibers in IGR subjects. Specific inhibition of both diacylglycerol acyltransferase (DGAT) 1 and 2 decreased fatty acid (FA) uptake by myotubes, whereas only DGAT2 inhibition also decreased fatty acid oxidation. Fatty acid uptake in myotubes was negatively correlated with the lactate thresholds of the respective donors. DGAT2 inhibition lowered acetate uptake and oxidation in myotubes from all cohorts whereas DGAT1 inhibition had no effect. A positive correlation between acetate oxidation in myotubes and resting metabolic rate (RMR) from fatty acid oxidation in vivo was observed. Myotubes from athletes and IGR had higher rates of de novo lipogenesis from acetate that were normalized by DGAT2 inhibition. Moreover, DGAT2 inhibition in myotubes also resulted in increased insulin-induced Akt phosphorylation. The differential effects of DGAT1 and DGAT2 inhibition suggest that the specialized role of DGAT2 in esterifying nascent diacylglycerols and de novo synthesized FA is associated with synthesis of a pool of triacylglycerol, which upon hydrolysis results in effectors that promote mitochondrial fatty acid oxidation but decrease insulin signaling in skeletal muscle cells.
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Affiliation(s)
- Zehra Irshad
- Translational and Experimental Medicine, Warwick Medical SchoolUniversity of WarwickCoventryUK
| | - Jenny Lund
- Section for Pharmacology and Pharmaceutical Biosciences, Department of PharmacyUniversity of OsloOsloNorway
| | - Anne Sillars
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary and Life SciencesUniversity of GlasgowGlasgowUK
| | - Nils Gunnar Løvsletten
- Section for Pharmacology and Pharmaceutical Biosciences, Department of PharmacyUniversity of OsloOsloNorway
| | - Seley Gharanei
- Translational and Experimental Medicine, Warwick Medical SchoolUniversity of WarwickCoventryUK
- Warwickshire Institute for the Study of Diabetes, Endocrinology and Metabolism (WISDEM)University Hospitals Coventry and Warwickshire NHS TrustCoventryUK
| | - Ian P. Salt
- School of Molecular Biosciences, College of Medical, Veterinary and Life SciencesUniversity of GlasgowGlasgowUK
| | - Dilys J. Freeman
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary and Life SciencesUniversity of GlasgowGlasgowUK
| | - Jason M. R. Gill
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary and Life SciencesUniversity of GlasgowGlasgowUK
| | - G. Hege Thoresen
- Section for Pharmacology and Pharmaceutical Biosciences, Department of PharmacyUniversity of OsloOsloNorway
- Department of Pharmacology, Institute of Clinical MedicineUniversity of OsloOsloNorway
| | - Arild C. Rustan
- Section for Pharmacology and Pharmaceutical Biosciences, Department of PharmacyUniversity of OsloOsloNorway
| | - Victor A. Zammit
- Translational and Experimental Medicine, Warwick Medical SchoolUniversity of WarwickCoventryUK
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Keizer HG, Brands R, Seinen W. An AMP Kinase-pathway dependent integrated stress response regulates ageing and longevity. Biogerontology 2023:10.1007/s10522-023-10024-3. [PMID: 36877293 DOI: 10.1007/s10522-023-10024-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/18/2023] [Indexed: 03/07/2023]
Abstract
The purpose of this article is to investigate the role of the AMP-kinase pathway (AMPK pathway) in the induction of a concomitant set of health benefits by exercise, numerous drugs, and health ingredients, all of which are adversely affected by ageing. Despite the AMPK pathway being frequently mentioned in relation to both these health effects and ageing, it appears challenging to understand how the activation of a single biochemical pathway by various treatments can produce such a diverse range of concurrent health benefits, involving so many organs. We discovered that the AMPK pathway functions as an integrated stress response system because of the presence of a feedback loop in it. This evolutionary conserved stress response system detects changes in AMP/ATP and NAD/NADH ratios, as well as the presence of potential toxins, and responds by activating a common protective transcriptional response that protects against aging and promotes longevity. The inactivation of the AMPK pathway with age most likely explains why ageing has a negative impact on the above-mentioned set of health benefits. We conclude that the presence of a feedback loop in the AMP-kinase pathway positions this pathway as an AMPK-ISR (AMP Kinase-dependent integrated stress response) system that responds to almost any type of (moderate) environmental stress by inducing various age-related health benefits and longevity.
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Affiliation(s)
- H G Keizer
- AMRIF Biotechnology, Agrobusiness Park 10, 6708 PW, Wageningen, The Netherlands.
| | - R Brands
- AMRIF Biotechnology, Agrobusiness Park 10, 6708 PW, Wageningen, The Netherlands.,Institute for Risk Assessment Sciences (IRAS), Yalelaan 1, 3584 CL, Utrecht, The Netherlands
| | - W Seinen
- AMRIF Biotechnology, Agrobusiness Park 10, 6708 PW, Wageningen, The Netherlands.,Institute for Risk Assessment Sciences (IRAS), Yalelaan 1, 3584 CL, Utrecht, The Netherlands
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Gold RS, Unkart JT, Larsen BA, Price CA, Cless M, Araneta MRG, Allison MA. Association of abdominal muscle area and density with glucose regulation: The multi-ethnic study of atherosclerosis (MESA). Diabetes Metab Res Rev 2022; 38:e3488. [PMID: 34328704 PMCID: PMC8800952 DOI: 10.1002/dmrr.3488] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 02/03/2023]
Abstract
AIMS Previous characterisation of body composition as a type 2 diabetes mellitus (T2DM) risk factor has largely focused on adiposity, but less is known about the independent role of skeletal muscle. We examined associations between abdominal muscle and measures of glucose regulation. MATERIALS AND METHODS Cross-sectional analysis of 1,891 adults enrolled in the Multi-Ethnic Study of Atherosclerosis. Multivariable regression assessed associations between abdominal muscle area and density (measured by computed tomography) with fasting glucose, homeostasis model assessment of insulin resistance (HOMA-IR), and prevalent T2DM (fasting glucose ≥126 mg/dL or medication use). RESULTS In minimally adjusted models (age, sex, race/ethnicity, income), a 1-SD increment in abdominal muscle area was associated with higher HOMA-IR (β = 0.20 ± SE 0.03; 95%CI: 0.15, 0.25; P < 0.01) and odds of T2DM (OR = 1.47; 95%CI: 1.18, 1.84; P < 0.01), while higher density was associated with lower fasting glucose (-4.49 ± 0.90; -6.26, -2.72; P < 0.01), HOMA-IR (-0.16 ± 0.02; -0.20, -0.12; P < 0.01), and odds of T2DM (0.64; 0.52, 0.77; P < 0.01). All associations persisted after adjustment for comorbidities and health behaviours. However, after controlling for height, BMI, and visceral adiposity, increasing muscle area became negatively associated with fasting glucose (-2.23 ± 1.01; -4.22, -0.24; P = 0.03), while density became positively associated with HOMA-IR (0.09 ± 0.02; 0.05, 0.13; P < 0.01). CONCLUSIONS Increasing muscle density was associated with salutary markers of glucose regulation, but associations inverted with further adjustment for body size and visceral adiposity. Conversely, after full adjustment, increasing muscle area was associated with lower fasting glucose, suggesting some patients may benefit from muscle-building interventions.
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Affiliation(s)
- Rebecca S Gold
- School of Medicine, University of California San Diego, La Jolla, California, USA
| | - Jonathan T Unkart
- Department of Family Medicine and Public Health, University of California San Diego, La Jolla, California, USA
| | - Britta A Larsen
- Department of Family Medicine and Public Health, University of California San Diego, La Jolla, California, USA
| | - Candice A Price
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, California, USA
| | - Mallory Cless
- School of Medicine, University of California San Diego, La Jolla, California, USA
| | - Maria Rosario G Araneta
- Department of Family Medicine and Public Health, University of California San Diego, La Jolla, California, USA
| | - Matthew A Allison
- Department of Family Medicine and Public Health, University of California San Diego, La Jolla, California, USA
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Kulawiec DG, Zhou T, Knopp JL, Chase JG. Continuous glucose monitoring to measure metabolic impact and recovery in sub-elite endurance athletes. Biomed Signal Process Control 2021. [DOI: 10.1016/j.bspc.2021.103059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Broussard JL, Perreault L, Macias E, Newsom SA, Harrison K, Bui HH, Milligan P, Roth KD, Nemkov T, D’Alessandro A, Brozinick JT, Bergman BC. Sex Differences in Insulin Sensitivity are Related to Muscle Tissue Acylcarnitine But Not Subcellular Lipid Distribution. Obesity (Silver Spring) 2021; 29:550-561. [PMID: 33624435 PMCID: PMC7927726 DOI: 10.1002/oby.23106] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/13/2020] [Accepted: 12/02/2020] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Sex differences in insulin sensitivity are present throughout the life-span, with men having a higher prevalence of insulin resistance and diabetes compared with women. Differences in lean mass, fat mass, and fat distribution-particularly ectopic fat-have all been postulated to contribute to the sexual dimorphism in diabetes risk. Emerging data suggest ectopic lipid composition and subcellular localization are most relevant; however, it is not known whether they explain sex differences in obesity-induced insulin resistance. METHODS To address this gap, this study evaluated insulin sensitivity and subcellular localization of intramuscular triacylglycerol, diacylglycerol, and sphingolipids as well as muscle acylcarnitines and serum lipidomics in people with obesity. RESULTS Insulin sensitivity was significantly lower in men (P < 0.05); however, no sex differences were found in localization of intramuscular triacylglycerol, diacylglycerol, or sphingolipids in skeletal muscle. In contrast, men had higher total muscle acylcarnitine (P < 0.05) and long-chain muscle acylcarnitine (P < 0.05), which were related to lower insulin sensitivity (r = -0.42, P < 0.05). Men also displayed higher serum ceramide (P = 0.05) and lysophosphatidylcholine (P < 0.01). CONCLUSIONS These data reveal novel sex-specific associations between lipid species involved in the coupling of mitochondrial fatty acid transport, β-oxidation, and tricarboxylic acid cycle flux that may provide therapeutic targets to improve insulin sensitivity.
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Affiliation(s)
- Josiane L. Broussard
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado, USA
| | - Leigh Perreault
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Emily Macias
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Sean A. Newsom
- School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Kathleen Harrison
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | - Paul Milligan
- North American Science Associates, Inc., Northwood, OH
| | | | - Travis Nemkov
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Angelo D’Alessandro
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | - Bryan C. Bergman
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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8
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Influence of Physical Activity on the Regulation of Disease of Elderly Persons with Metabolic Syndrome. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18010275. [PMID: 33401397 PMCID: PMC7796354 DOI: 10.3390/ijerph18010275] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 01/24/2023]
Abstract
Metabolic syndrome is a group of metabolic risk factors whose combination significantly contributes to the development of the risk of cardiovascular disease, diabetes, stroke, some cancers and is a clear indicator of morbidity rate. The aim of this study was to identify physical activity programs that can successfully influence the reduction of risk factors in metabolic syndrome of the elderly. Subjects were aged between 60 and 80 years, had three of five signs of metabolic syndrome, and were randomly divided into three groups of 20 subjects. The first group conducted a continuous cycling ergometer (55% VO2max), the second group a physical activity strength program and the third was a control group. Before and after the experimental treatment body composition, biochemical parameters, functional parameters, cardiovascular functions, metabolic and hematological system were determined. Significant differences between control and experimental groups were determined using MANOVA. The training effects of the experimental and control groups were determined using the ANOVA for repeated measurements with Bonfferoni correction. The results showed that a physical activity program of strength has a better effect on disease regulation in the elderly with metabolic syndrome than a moderate-intensity physical activity program which also has a significant change but in less variables.
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9
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Kahn D, Perreault L, Macias E, Zarini S, Newsom SA, Strauss A, Kerege A, Harrison K, Snell-Bergeon J, Bergman BC. Subcellular localisation and composition of intramuscular triacylglycerol influence insulin sensitivity in humans. Diabetologia 2021; 64:168-180. [PMID: 33128577 PMCID: PMC7718332 DOI: 10.1007/s00125-020-05315-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/25/2020] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Subcellular localisation is an important factor in the known impact of bioactive lipids, such as diacylglycerol and sphingolipids, on insulin sensitivity in skeletal muscle; yet, the role of localised intramuscular triacylglycerol (IMTG) is yet to be described. Excess accumulation of IMTG in skeletal muscle is associated with insulin resistance, and we hypothesised that differences in subcellular localisation and composition of IMTG would relate to metabolic health status in humans. METHODS We evaluated subcellular localisation of IMTG in lean participants, endurance-trained athletes, individuals with obesity and individuals with type 2 diabetes using LC-MS/MS of fractionated muscle biopsies and insulin clamps. RESULTS Insulin sensitivity was significantly different between each group (athletes>lean>obese>type 2 diabetes; p < 0.001). Sarcolemmal IMTG was significantly greater in individuals with obesity and type 2 diabetes compared with lean control participants and athletes, but individuals with type 2 diabetes were the only group with significantly increased saturated IMTG. Sarcolemmal IMTG was inversely related to insulin sensitivity. Nuclear IMTG was significantly greater in individuals with type 2 diabetes compared with lean control participants and athletes, and total and saturated IMTG localised in the nucleus had a significant inverse relationship with insulin sensitivity. Total cytosolic IMTG was not different between groups, but saturated cytosolic IMTG species were significantly increased in individuals with type 2 diabetes compared with all other groups. There were no significant differences between groups for IMTG concentration in the mitochondria/endoplasmic reticulum. CONCLUSIONS/INTERPRETATION These data reveal previously unknown differences in subcellular IMTG localisation based on metabolic health status and indicate the influence of sarcolemmal and nuclear IMTG on insulin sensitivity. Additionally, these studies suggest saturated IMTG may be uniquely deleterious for muscle insulin sensitivity. Graphical abstract.
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Affiliation(s)
- Darcy Kahn
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Leigh Perreault
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Emily Macias
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Simona Zarini
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | - Allison Strauss
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Anna Kerege
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kathleen Harrison
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Janet Snell-Bergeon
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Bryan C Bergman
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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10
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Seibert JT, Najt CP, Heden TD, Mashek DG, Chow LS. Muscle Lipid Droplets: Cellular Signaling to Exercise Physiology and Beyond. Trends Endocrinol Metab 2020; 31:928-938. [PMID: 32917515 PMCID: PMC7704552 DOI: 10.1016/j.tem.2020.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/09/2020] [Accepted: 08/13/2020] [Indexed: 12/21/2022]
Abstract
Conventionally viewed as energy storage depots, lipid droplets (LDs) play a central role in muscle lipid metabolism and intracellular signaling, as recognized by recent advances in our biological understanding. Specific subpopulations of muscle LDs, defined by location and associated proteins, are responsible for distinct biological functions. In this review, the traditional view of muscle LDs is examined, and the emerging role of LDs in intracellular signaling is highlighted. The effects of chronic and acute exercise on muscle LD metabolism and signaling is discussed. In conclusion, future directions for muscle LD research are identified. The primary focus will be on human studies, with inclusion of select animal/cellular/non-muscle studies as appropriate, to provide the underlying mechanisms driving the observed findings.
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Affiliation(s)
- Jacob T Seibert
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Charles P Najt
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Timothy D Heden
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN 55455, USA
| | - Lisa S Chow
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN 55455, USA.
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11
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Edmunds LR, Huckestein BR, Kahn M, Zhang D, Chu Y, Zhang Y, Wendell SG, Shulman GI, Jurczak MJ. Hepatic insulin sensitivity is improved in high-fat diet-fed Park2 knockout mice in association with increased hepatic AMPK activation and reduced steatosis. Physiol Rep 2020; 7:e14281. [PMID: 31724300 PMCID: PMC6854109 DOI: 10.14814/phy2.14281] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Park2 is an E3 ubiquitin ligase known for its role in mitochondrial quality control via the mitophagy pathway. Park2 KO mice are protected from diet‐induced obesity and hepatic insulin sensitivity is improved in high‐fat diet (HFD)‐fed Park2 KO mice even under body weight‐matched conditions. In order to better understand the cellular mechanism by which Park2 KO mice are protected from diet‐induced hepatic insulin resistance, we determined changes in multiple pathways commonly associated with the pathogenesis of insulin resistance, namely levels of bioactive lipid species, activation of the endoplasmic reticulum (ER) stress response and changes in cytokine levels and signaling. We report for the first time that whole‐body insulin sensitivity is unchanged in regular chow (RC)‐fed Park2 KO mice, and that liver diacylglycerol levels are reduced and very‐long‐chain ceramides are increased in Park2 KO mice fed HFD for 1 week. Hepatic transcriptional markers of the ER stress response were reduced and plasma tumor necrosis factor‐α (TNFα), interleukin‐6 and −10 (IL6, IL10) were significantly increased in HFD‐fed Park2 KO mice; however, there were no detectable differences in hepatic inflammatory signaling pathways between groups. Interestingly, hepatic adenylate charge was reduced in HFD‐fed Park2 KO liver and was associated increased activation of AMPK. These data suggest that negative energy balance that contributed to protection from obesity during chronic HFD manifested at the level of the hepatocyte during short‐term HFD feeding and contributed to the improved hepatic insulin sensitivity.
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Affiliation(s)
- Lia R Edmunds
- Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Brydie R Huckestein
- Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Mario Kahn
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Dongyan Zhang
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Yanxia Chu
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Yingze Zhang
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Stacy G Wendell
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Gerald I Shulman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.,Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Michael J Jurczak
- Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.,Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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12
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Bergman BC, Goodpaster BH. Exercise and Muscle Lipid Content, Composition, and Localization: Influence on Muscle Insulin Sensitivity. Diabetes 2020; 69:848-858. [PMID: 32312901 DOI: 10.2337/dbi18-0042] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 02/17/2020] [Indexed: 11/13/2022]
Abstract
Accumulation of lipid in skeletal muscle is thought to be related to the development of insulin resistance and type 2 diabetes. Initial work in this area focused on accumulation of intramuscular triglyceride; however, bioactive lipids such as diacylglycerols and sphingolipids are now thought to play an important role. Specific species of these lipids appear to be more negative toward insulin sensitivity than others. Adding another layer of complexity, localization of lipids within the cell appears to influence the relationship between these lipids and insulin sensitivity. This article summarizes how accumulation of total lipids, specific lipid species, and localization of lipids influence insulin sensitivity in humans. We then focus on how these aspects of muscle lipids are impacted by acute and chronic aerobic and resistance exercise training. By understanding how exercise alters specific species and localization of lipids, it may be possible to uncover specific lipids that most heavily impact insulin sensitivity.
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13
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Reidy PT, Mahmassani ZS, McKenzie AI, Petrocelli JJ, Summers SA, Drummond MJ. Influence of Exercise Training on Skeletal Muscle Insulin Resistance in Aging: Spotlight on Muscle Ceramides. Int J Mol Sci 2020; 21:ijms21041514. [PMID: 32098447 PMCID: PMC7073171 DOI: 10.3390/ijms21041514] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 12/15/2022] Open
Abstract
Intramuscular lipid accumulation has been associated with insulin resistance (IR), aging, diabetes, dyslipidemia, and obesity. A substantial body of evidence has implicated ceramides, a sphingolipid intermediate, as potent antagonists of insulin action that drive insulin resistance. Indeed, genetic mouse studies that lower ceramides are potently insulin sensitizing. Surprisingly less is known about how physical activity (skeletal muscle contraction) regulates ceramides, especially in light that muscle contraction regulates insulin sensitivity. The purpose of this review is to critically evaluate studies (rodent and human) concerning the relationship between skeletal muscle ceramides and IR in response to increased physical activity. Our review of the literature indicates that chronic exercise reduces ceramide levels in individuals with obesity, diabetes, or hyperlipidemia. However, metabolically healthy individuals engaged in increased physical activity can improve insulin sensitivity independent of changes in skeletal muscle ceramide content. Herein we discuss these studies and provide context regarding the technical limitations (e.g., difficulty assessing the myriad ceramide species, the challenge of obtaining information on subcellular compartmentalization, and the paucity of flux measurements) and a lack of mechanistic studies that prevent a more sophisticated assessment of the ceramide pathway during increased contractile activity that lead to divergences in skeletal muscle insulin sensitivity.
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Affiliation(s)
- Paul T. Reidy
- Department of Kinesiology and Health, Miami University, 420 S Oak St, Oxford, OH 45056, USA;
| | - Ziad S. Mahmassani
- Departments of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA; (Z.S.M.); (A.I.M.); (J.J.P.)
| | - Alec I. McKenzie
- Departments of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA; (Z.S.M.); (A.I.M.); (J.J.P.)
| | - Jonathan J. Petrocelli
- Departments of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA; (Z.S.M.); (A.I.M.); (J.J.P.)
| | - Scott A. Summers
- Department of Nutrition and Integrative Physiology, University of Utah, 250 1850 E, Salt Lake City, UT 84112, USA;
| | - Micah J. Drummond
- Departments of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84018, USA; (Z.S.M.); (A.I.M.); (J.J.P.)
- Correspondence:
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14
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Savage DB, Watson L, Carr K, Adams C, Brage S, Chatterjee KK, Hodson L, Boesch C, Kemp GJ, Sleigh A. Accumulation of saturated intramyocellular lipid is associated with insulin resistance. J Lipid Res 2019; 60:1323-1332. [PMID: 31048405 PMCID: PMC6602127 DOI: 10.1194/jlr.m091942] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/11/2019] [Indexed: 12/17/2022] Open
Abstract
Intramyocellular lipid (IMCL) accumulation has been linked to both insulin-resistant and insulin-sensitive (athletes) states. Biochemical analysis of intramuscular triglyceride composition is confounded by extramyocellular triglycerides in biopsy samples, and hence the specific composition of IMCLs is unknown in these states. 1H magnetic resonance spectroscopy (MRS) can be used to overcome this problem. Thus, we used a recently validated 1H MRS method to compare the compositional saturation index (CH2:CH3) and concentration independent of the composition (CH3) of IMCLs in the soleus and tibialis anterior muscles of 16 female insulin-resistant lipodystrophic subjects with that of age- and gender-matched athletes (n = 14) and healthy controls (n = 41). The IMCL CH2:CH3 ratio was significantly higher in both muscles of the lipodystrophic subjects compared with controls but was similar in athletes and controls. IMCL CH2:CH3 was dependent on the IMCL concentration in the controls and, after adjusting the compositional index for quantity (CH2:CH3adj), could distinguish lipodystrophics from athletes. This CH2:CH3adj marker had a stronger relationship with insulin resistance than IMCL concentration alone and was inversely related to VO2max. The association of insulin resistance with the accumulation of saturated IMCLs is consistent with a potential pathogenic role for saturated fat and the reported benefits of exercise and diet in insulin-resistant states.
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Affiliation(s)
- David B Savage
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Laura Watson
- National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Katie Carr
- National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Claire Adams
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Soren Brage
- MRC Epidemiology Unit University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - Krishna K Chatterjee
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge, United Kingdom.,National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Chris Boesch
- Department of Clinical Research and Radiology AMSM, University Bern, Bern, Switzerland
| | - Graham J Kemp
- Department of Musculoskeletal Biology University of Liverpool and MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Liverpool, United Kingdom
| | - Alison Sleigh
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge, United Kingdom .,National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust Cambridge Biomedical Campus, Cambridge, United Kingdom.,Wolfson Brain Imaging Centre University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
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15
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Supruniuk E, Mikłosz A, Chabowski A, Łukaszuk B. Dose- and time-dependent alterations in lipid metabolism after pharmacological PGC-1α activation in L6 myotubes. J Cell Physiol 2018; 234:11923-11941. [PMID: 30523639 PMCID: PMC6587770 DOI: 10.1002/jcp.27872] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/12/2018] [Indexed: 12/29/2022]
Abstract
Pyrroloquinoline quinone (PQQ) acts as a powerful modulator of PGC‐1α activation and therefore regulates multiple pathways involved in cellular energy homeostasis. In the present study, we assessed the effects of L6 myotubes incubation with 0.5, 1, and 3 μM PQQ solution for 2 and 24 hr with respect to the cells' lipid metabolism. We demonstrated that PQQ significantly elevates PGC‐1α content in a dose‐ and time‐dependent manner with the highest efficiency for 0.5 and 1 µM. The level of free fatty acids was diminished (24 hr: −66%), while an increase in triacylglycerol (TAG) amount was most pronounced after 0.5 μM (2 hr: +93%, 24 hr: +139%) treatment. Ceramide (CER) content was elevated after 2 hr incubation with 0.5 µM and after prolonged exposure to all PQQ concentrations. The cells treated with PQQ for 2 hr exhibited decreased sphinganine (SFA) and sphinganine‐1‐phosphate (SFA1P) level, while 24 hr incubation resulted in an elevated sphingosine (SFO) amount. In summary, PGC‐1α activation promotes TAG and CER synthesis.
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Affiliation(s)
- Elżbieta Supruniuk
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Agnieszka Mikłosz
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Bartłomiej Łukaszuk
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
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16
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Xu S, Zhang X, Liu P. Lipid droplet proteins and metabolic diseases. Biochim Biophys Acta Mol Basis Dis 2018; 1864:1968-1983. [DOI: 10.1016/j.bbadis.2017.07.019] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/14/2017] [Accepted: 07/19/2017] [Indexed: 12/13/2022]
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17
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Daemen S, van Polanen N, Hesselink MKC. The effect of diet and exercise on lipid droplet dynamics in human muscle tissue. ACTA ACUST UNITED AC 2018. [PMID: 29514886 DOI: 10.1242/jeb.167015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The majority of fat in the human body is stored as triacylglycerols in white adipose tissue. In the obese state, adipose tissue mass expands and excess lipids are stored in non-adipose tissues, such as skeletal muscle. Lipids are stored in skeletal muscle in the form of small lipid droplets. Although originally viewed as dull organelles that simply store lipids as a consequence of lipid overflow from adipose tissue, lipid droplets are now recognized as key components in the cell that exert a variety of relevant functions in multiple tissues (including muscle). Here, we review the effect of diet and exercise interventions on myocellular lipid droplets and their putative role in insulin sensitivity from a human perspective. We also provide an overview of lipid droplet biology and identify gaps for future research.
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Affiliation(s)
- Sabine Daemen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Nynke van Polanen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Matthijs K C Hesselink
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
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18
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Moxley MA, Vinnakota KC, Bazil JN, Qi NR, Beard DA. Systems-level computational modeling demonstrates fuel selection switching in high capacity running and low capacity running rats. PLoS Comput Biol 2018; 14:e1005982. [PMID: 29474500 PMCID: PMC5841818 DOI: 10.1371/journal.pcbi.1005982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 03/07/2018] [Accepted: 01/16/2018] [Indexed: 12/24/2022] Open
Abstract
High capacity and low capacity running rats, HCR and LCR respectively, have been bred to represent two extremes of running endurance and have recently demonstrated disparities in fuel usage during transient aerobic exercise. HCR rats can maintain fatty acid (FA) utilization throughout the course of transient aerobic exercise whereas LCR rats rely predominantly on glucose utilization. We hypothesized that the difference between HCR and LCR fuel utilization could be explained by a difference in mitochondrial density. To test this hypothesis and to investigate mechanisms of fuel selection, we used a constraint-based kinetic analysis of whole-body metabolism to analyze transient exercise data from these rats. Our model analysis used a thermodynamically constrained kinetic framework that accounts for glycolysis, the TCA cycle, and mitochondrial FA transport and oxidation. The model can effectively match the observed relative rates of oxidation of glucose versus FA, as a function of ATP demand. In searching for the minimal differences required to explain metabolic function in HCR versus LCR rats, it was determined that the whole-body metabolic phenotype of LCR, compared to the HCR, could be explained by a ~50% reduction in total mitochondrial activity with an additional 5-fold reduction in mitochondrial FA transport activity. Finally, we postulate that over sustained periods of exercise that LCR can partly overcome the initial deficit in FA catabolic activity by upregulating FA transport and/or oxidation processes. Our bodies consume carbohydrates, fats, and amino acids as fuels, utilizing various catabolic pathways to transfer the energy required for normal physiological functions. The way these pathways function can have an important impact on overall health. While most catabolic pathways are known, we are still striving to understand how these pathways interact, are controlled, and change during exercise and in disease. Here, we have used computer modeling as a tool to understand fuel utilization differences during exercise for two animal models. High capacity running rats (HCR) were used as a healthy, fit cohort, and low capacity running rats (LCR) were used as a sedentary and disease-prone cohort. Our computer model results show that the HCRs are superior at fat utilization compared to LCRs because of their increased ability to transport and catabolize fatty acids. We postulate that these differences depend on exercise intensity and duration, such that longer acclimation periods may minimize fuel utilization differences between these rats.
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Affiliation(s)
- Michael A. Moxley
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kalyan C. Vinnakota
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jason N. Bazil
- Department of Physiology, Michigan State University, East Lansing, MI, United States of America
| | - Nathan R. Qi
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, United States of America
| | - Daniel A. Beard
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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19
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Perreault L, Newsom SA, Strauss A, Kerege A, Kahn DE, Harrison KA, Snell-Bergeon JK, Nemkov T, D'Alessandro A, Jackman MR, MacLean PS, Bergman BC. Intracellular localization of diacylglycerols and sphingolipids influences insulin sensitivity and mitochondrial function in human skeletal muscle. JCI Insight 2018; 3:96805. [PMID: 29415895 DOI: 10.1172/jci.insight.96805] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/12/2017] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Accumulation of diacylglycerol (DAG) and sphingolipids is thought to promote skeletal muscle insulin resistance by altering cellular signaling specific to their location. However,the subcellular localization of bioactive lipids in human skeletal muscle is largely unknown. METHODS We evaluated subcellular localization of skeletal muscle DAGs and sphingolipids in lean individuals (n = 15), endurance-trained athletes (n = 16), and obese men and women with (n = 12) and without type 2 diabetes (n = 15). Muscle biopsies were fractionated into sarcolemmal, cytosolic, mitochondrial/ER, and nuclear compartments. Lipids were measured using liquid chromatography tandem mass spectrometry, and insulin sensitivity was measured using hyperinsulinemic-euglycemic clamp. RESULTS Sarcolemmal 1,2-DAGs were not significantly related to insulin sensitivity. Sarcolemmal ceramides were inversely related to insulin sensitivity, with a significant relationship found for the C18:0 species. Sarcolemmal sphingomyelins were also inversely related to insulin sensitivity, with the strongest relationships found for the C18:1, C18:0, and C18:2 species. In the mitochondrial/ER and nuclear fractions, 1,2-DAGs were positively related to, while ceramides were inversely related to, insulin sensitivity. Cytosolic lipids as well as 1,3-DAG, dihydroceramides, and glucosylceramides in any compartment were not related to insulin sensitivity. All sphingolipids but only specific DAGs administered to isolated mitochondria decreased mitochondrial state 3 respiration. CONCLUSION These data reveal previously unknown differences in subcellular localization of skeletal muscle DAGs and sphingolipids that relate to whole-body insulin sensitivity and mitochondrial function in humans. These data suggest that whole-cell concentrations of lipids obscure meaningful differences in compartmentalization and suggest that subcellular localization of lipids should be considered when developing therapeutic interventions to treat insulin resistance. FUNDING National Institutes of Health General Clinical Research Center (RR-00036), National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (R01DK089170), NIDDK (T32 DK07658), and Colorado Nutrition Obesity Research Center (P30DK048520).
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Affiliation(s)
- Leigh Perreault
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Sean A Newsom
- School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Allison Strauss
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Anna Kerege
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Darcy E Kahn
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Kathleen A Harrison
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Janet K Snell-Bergeon
- Barbara Davis Center for Childhood Diabetes, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Matthew R Jackman
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Paul S MacLean
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Bryan C Bergman
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
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20
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Bergman BC, Perreault L, Strauss A, Bacon S, Kerege A, Harrison K, Brozinick JT, Hunerdosse DM, Playdon MC, Holmes W, Bui HH, Sanders P, Siddall P, Wei T, Thomas MK, Kuo MS, Eckel RH. Intramuscular triglyceride synthesis: importance in muscle lipid partitioning in humans. Am J Physiol Endocrinol Metab 2018; 314:E152-E164. [PMID: 28978544 PMCID: PMC5866414 DOI: 10.1152/ajpendo.00142.2017] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Intramuscular triglyceride (IMTG) concentration is elevated in insulin-resistant individuals and was once thought to promote insulin resistance. However, endurance-trained athletes have equivalent concentration of IMTG compared with individuals with type 2 diabetes, and have very low risk of diabetes, termed the "athlete's paradox." We now know that IMTG synthesis is positively related to insulin sensitivity, but the exact mechanisms for this are unclear. To understand the relationship between IMTG synthesis and insulin sensitivity, we measured IMTG synthesis in obese control subjects, endurance-trained athletes, and individuals with type 2 diabetes during rest, exercise, and recovery. IMTG synthesis rates were positively related to insulin sensitivity, cytosolic accumulation of DAG, and decreased accumulation of C18:0 ceramide and glucosylceramide. Greater rates of IMTG synthesis in athletes were not explained by alterations in FFA concentration, DGAT1 mRNA expression, or protein content. IMTG synthesis during exercise in Ob and T2D indicate utilization as a fuel despite unchanged content, whereas IMTG concentration decreased during exercise in athletes. mRNA expression for genes involved in lipid desaturation and IMTG synthesis were increased after exercise and recovery. Further, in a subset of individuals, exercise decreased cytosolic and membrane di-saturated DAG content, which may help explain insulin sensitization after acute exercise. These data suggest IMTG synthesis rates may influence insulin sensitivity by altering intracellular lipid localization, and decreasing specific ceramide species that promote insulin resistance.
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Affiliation(s)
- Bryan C Bergman
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Leigh Perreault
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Allison Strauss
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Samantha Bacon
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Anna Kerege
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | | | | | | | - Mary C Playdon
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | | | | | | | | | - Tao Wei
- Eli Lilly, Indianapolis, Indiana
| | | | | | - Robert H Eckel
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
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21
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Søndergaard E, Nielsen S. VLDL triglyceride accumulation in skeletal muscle and adipose tissue in type 2 diabetes. Curr Opin Lipidol 2018; 29:42-47. [PMID: 29135689 DOI: 10.1097/mol.0000000000000471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Insulin resistance is closely linked to accumulation of lipid outside adipose tissue (ectopic fat storage). VLDL particles transport lipids from the liver to peripheral tissues. However, whether abnormalities in VLDL-triglyceride storage in muscle and adipose tissue exist in type 2 diabetes has previously been unknown, primarily because of methodological difficulties. Here, we review recent research on VLDL-triglyceride storage. RECENT FINDINGS In a recent study, men with type 2 diabetes had increased skeletal muscle VLDL-triglyceride storage compared to weight-matched nondiabetic men, potentially leading to intramyocellular triglyceride accumulation. In contrast, studies of adipose tissue VLDL-triglyceride storage have shown similar storage capacity in men with and without diabetes, both in the postabsorptive and the postprandial period. In the initial submission, studies have failed to show associations between lipoprotein lipase activity, considered the rate-limiting step in storage of lipids from lipoproteins, and VLDL-TG storage in both muscle and adipose tissue. SUMMARY Differences in muscle VLDL-triglyceride storage may lead to ectopic fat storage and contribute to the development of type 2 diabetes, whereas the ability to store VLDL-triglyceride in adipose tissue is preserved in type 2 diabetes.
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Affiliation(s)
- Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus C
- Danish Diabetes Academy, Odense University Hospital, Odense C, Denmark
| | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus C
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22
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Metabolic and molecular changes associated with the increased skeletal muscle insulin action 24-48 h after exercise in young and old humans. Biochem Soc Trans 2018; 46:111-118. [PMID: 29330356 DOI: 10.1042/bst20170198] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/23/2017] [Accepted: 11/24/2017] [Indexed: 12/25/2022]
Abstract
The molecular and metabolic mechanisms underlying the increase in insulin sensitivity (i.e. increased insulin-stimulated skeletal muscle glucose uptake, phosphorylation and storage as glycogen) observed from 12 to 48 h following a single bout of exercise in humans remain unresolved. Moreover, whether these mechanisms differ with age is unclear. It is well established that a single bout of exercise increases the translocation of the glucose transporter, GLUT4, to the plasma membrane. Previous research using unilateral limb muscle contraction models in combination with hyperinsulinaemia has demonstrated that the increase in insulin sensitivity and glycogen synthesis 24 h after exercise is also associated with an increase in hexokinase II (HKII) mRNA and protein content, suggesting an increase in the capacity of the muscle to phosphorylate glucose and divert it towards glycogen synthesis. Interestingly, this response is altered in older individuals for up to 48 h post exercise and is associated with molecular changes in skeletal muscle tissue that are indicative of reduced lipid oxidation, increased lipogenesis, increased inflammation and a relative inflexibility of changes in intramyocellular lipid (IMCL) content. Reduced insulin sensitivity (insulin resistance) is generally related to IMCL content, particularly in the subsarcolemmal (SSL) region, and both are associated with increasing age. Recent research has demonstrated that ageing per se appears to cause an exacerbated lipolytic response to exercise that may result in SSL IMCL accumulation. Further research is required to determine if increased IMCL content affects HKII expression in the days after exercise in older individuals, and the effect of this on skeletal muscle insulin action.
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23
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Dotzert MS, McDonald MW, Murray MR, Nickels JZ, Noble EG, Melling CWJ. Effect of Combined Exercise Versus Aerobic-Only Training on Skeletal Muscle Lipid Metabolism in a Rodent Model of Type 1 Diabetes. Can J Diabetes 2017; 42:404-411. [PMID: 29212609 DOI: 10.1016/j.jcjd.2017.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 09/10/2017] [Accepted: 09/25/2017] [Indexed: 12/18/2022]
Abstract
OBJECTIVES Abnormal skeletal muscle lipid metabolism is associated with insulin resistance in people with type 1 diabetes. Although lipid metabolism is restored with aerobic exercise training, the risk for postexercise hypoglycemia is increased with this modality. Integrating resistance and aerobic exercise is associated with reduced hypoglycemic risk; however, the effects of this exercise modality on lipid metabolism and insulin resistance remain unknown. We compared the effects of combined (aerobic + resistance) versus aerobic exercise training on oxidative capacity and muscle lipid metabolism in a rat model of type 1 diabetes. METHODS Male Sprague-Dawley rats were divided into 4 groups: sedentary control (C), sedentary control + diabetes (CD), diabetes + high-intensity aerobic exercise (DAE) and diabetes + combined aerobic and resistance exercise (DARE). Following diabetes induction (20 mg/kg streptozotocin over five days), DAE rats ran for 12 weeks (5 days/week for 1 hour) on a motorized treadmill (27 m/min at a 6-degree grade), and DARE rats alternated daily between running and incremental weighted ladder climbing. RESULTS After training, DAE showed reduced muscle CD36 protein content and lipid content compared to CD (p≤0.05). DAE rats also had significantly increased citrate synthase (CS) activity compared to CD (p≤0.05). DARE rats showed reduced CD36 protein content compared to CD and increased CS activity compared to CD and DAE rats (p≤0.05). DARE rats demonstrated increased skeletal muscle lipid staining, elevated lipin-1 protein content and insulin sensitivity (p≤0.05). CONCLUSIONS Integration of aerobic and resistance exercise may exert a synergistic effect, producing adaptations characteristic of the "athlete's paradox," including increased capacity to store and oxidize lipids.
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Affiliation(s)
- Michelle S Dotzert
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Matthew W McDonald
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Michael R Murray
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - J Zachary Nickels
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Earl G Noble
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada
| | - C W James Melling
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada.
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ALJohani AM, Syed DN, Ntambi JM. Insights into Stearoyl-CoA Desaturase-1 Regulation of Systemic Metabolism. Trends Endocrinol Metab 2017; 28:831-842. [PMID: 29089222 PMCID: PMC5701860 DOI: 10.1016/j.tem.2017.10.003] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 12/15/2022]
Abstract
Stearoyl-coenzyme A desaturase 1 (SCD1) is a central regulator of fuel metabolism and may represent a therapeutic target to control obesity and the progression of related metabolic diseases including type 2 diabetes and hepatic steatosis. SCD1 catalyzes the synthesis of monounsaturated fatty acids (MUFAs), mainly oleate and palmitoleate, which are important in controlling weight gain in response to feeding high carbohydrate diets. In this review, we evaluate the role of SCD1 isoform in the regulation of lipid and glucose metabolism in metabolic tissues. These highlights of recent findings are aimed toward advancing our understanding of the role of SCD1 in the development of metabolic diseases, which may help evaluate the possible health outcomes of modulating MUFA levels through targeting SCD1 activity.
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Affiliation(s)
- Ahmed M ALJohani
- School of Medicine and Public Health, Endocrinology and Reproductive Physiology Graduate Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA; King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, Riyadh, 11426, Saudi Arabia
| | - Deeba N Syed
- School of Medicine and Public Health, Department of Dermatology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - James M Ntambi
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
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25
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Supruniuk E, Mikłosz A, Chabowski A. The Implication of PGC-1α on Fatty Acid Transport across Plasma and Mitochondrial Membranes in the Insulin Sensitive Tissues. Front Physiol 2017; 8:923. [PMID: 29187824 PMCID: PMC5694779 DOI: 10.3389/fphys.2017.00923] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/31/2017] [Indexed: 12/21/2022] Open
Abstract
PGC-1α coactivator plays a decisive role in the maintenance of lipid balance via engagement in numerous metabolic processes (i.e., Krebs cycle, β-oxidation, oxidative phosphorylation and electron transport chain). It constitutes a link between fatty acids import and their complete oxidation or conversion into bioactive fractions through the coordination of both the expression and subcellular relocation of the proteins involved in fatty acid transmembrane movement. Studies on cell lines and/or animal models highlighted the existence of an upregulation of the total and mitochondrial FAT/CD36, FABPpm and FATPs content in skeletal muscle in response to PGC-1α stimulation. On the other hand, the association between PGC-1α level or activity and the fatty acids transport in the heart and adipocytes is still elusive. So far, the effects of PGC-1α on the total and sarcolemmal expression of FAT/CD36, FATP1, and FABPpm in cardiomyocytes have been shown to vary in relation to the type of PPAR that was coactivated. In brown adipose tissue (BAT) PGC-1α knockdown was linked with a decreased level of lipid metabolizing enzymes and fatty acid transporters (FAT/CD36, FABP3), whereas the results obtained for white adipose tissue (WAT) remain contradictory. Furthermore, dysregulation in lipid turnover is often associated with insulin intolerance, which suggests the coactivator's potential role as a therapeutic target.
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Affiliation(s)
- Elżbieta Supruniuk
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Agnieszka Mikłosz
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
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Carta G, Murru E, Banni S, Manca C. Palmitic Acid: Physiological Role, Metabolism and Nutritional Implications. Front Physiol 2017; 8:902. [PMID: 29167646 PMCID: PMC5682332 DOI: 10.3389/fphys.2017.00902] [Citation(s) in RCA: 353] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 10/24/2017] [Indexed: 12/19/2022] Open
Abstract
Palmitic acid (PA) has been for long time negatively depicted for its putative detrimental health effects, shadowing its multiple crucial physiological activities. PA is the most common saturated fatty acid accounting for 20–30% of total fatty acids in the human body and can be provided in the diet or synthesized endogenously via de novo lipogenesis (DNL). PA tissue content seems to be controlled around a well-defined concentration, and changes in its intake do not influence significantly its tissue concentration because the exogenous source is counterbalanced by PA endogenous biosynthesis. Particular physiopathological conditions and nutritional factors may strongly induce DNL, resulting in increased tissue content of PA and disrupted homeostatic control of its tissue concentration. The tight homeostatic control of PA tissue concentration is likely related to its fundamental physiological role to guarantee membrane physical properties but also to consent protein palmitoylation, palmitoylethanolamide (PEA) biosynthesis, and in the lung an efficient surfactant activity. In order to maintain membrane phospholipids (PL) balance may be crucial an optimal intake of PA in a certain ratio with unsaturated fatty acids, especially PUFAs of both n-6 and n-3 families. However, in presence of other factors such as positive energy balance, excessive intake of carbohydrates (in particular mono and disaccharides), and a sedentary lifestyle, the mechanisms to maintain a steady state of PA concentration may be disrupted leading to an over accumulation of tissue PA resulting in dyslipidemia, hyperglycemia, increased ectopic fat accumulation and increased inflammatory tone via toll-like receptor 4. It is therefore likely that the controversial data on the association of dietary PA with detrimental health effects, may be related to an excessive imbalance of dietary PA/PUFA ratio which, in certain physiopathological conditions, and in presence of an enhanced DNL, may further accelerate these deleterious effects.
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Affiliation(s)
- Gianfranca Carta
- Dipartimento Scienze Biomediche, Università degli studi di Cagliari, Cagliari, Italy
| | - Elisabetta Murru
- Dipartimento Scienze Biomediche, Università degli studi di Cagliari, Cagliari, Italy
| | - Sebastiano Banni
- Dipartimento Scienze Biomediche, Università degli studi di Cagliari, Cagliari, Italy
| | - Claudia Manca
- Dipartimento Scienze Biomediche, Università degli studi di Cagliari, Cagliari, Italy
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Benziane B, Borg ML, Tom RZ, Riedl I, Massart J, Björnholm M, Gilbert M, Chibalin AV, Zierath JR. DGKζ deficiency protects against peripheral insulin resistance and improves energy metabolism. J Lipid Res 2017; 58:2324-2333. [PMID: 29066466 DOI: 10.1194/jlr.m079723] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/16/2017] [Indexed: 12/25/2022] Open
Abstract
Diacylglycerol kinases (DGKs) regulate the balance between diacylglycerol (DAG) and phosphatidic acid. DGKζ is highly abundant in skeletal muscle and induces fiber hypertrophy. We hypothesized that DGKζ influences functional and metabolic adaptations in skeletal muscle and whole-body fuel utilization. DAG content was increased in skeletal muscle and adipose tissue, but unaltered in liver of DGKζ KO mice. Linear growth, body weight, fat mass, and lean mass were reduced in DGKζ KO versus wild-type mice. Conversely, male DGKζ KO and wild-type mice displayed a similar robust increase in plantaris weight after functional overload, suggesting that DGKζ is dispensable for muscle hypertrophy. Although glucose tolerance was similar, insulin levels were reduced in high-fat diet (HFD)-fed DGKζ KO versus wild-type mice. Submaximal insulin-stimulated glucose transport and p-Akt Ser473 were increased, suggesting enhanced skeletal muscle insulin sensitivity. Energy homeostasis was altered in DGKζ KO mice, as evidenced by an elevated respiratory exchange ratio, independent of altered physical activity or food intake. In conclusion, DGKζ deficiency increases tissue DAG content and leads to modest growth retardation, reduced adiposity, and protection against insulin resistance. DGKζ plays a role in the control of growth and metabolic processes, further highlighting specialized functions of DGK isoforms in type 2 diabetes pathophysiology.
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Affiliation(s)
- Boubacar Benziane
- Department of Physiology and Pharmacology Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Melissa L Borg
- Department of Physiology and Pharmacology Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Robby Z Tom
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Isabelle Riedl
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Julie Massart
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Marie Björnholm
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Marc Gilbert
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Juleen R Zierath
- Department of Physiology and Pharmacology Karolinska Institutet, 171 77 Stockholm, Sweden .,Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
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Lipid droplet remodelling and reduced muscle ceramides following sprint interval and moderate-intensity continuous exercise training in obese males. Int J Obes (Lond) 2017; 41:1745-1754. [PMID: 28736444 DOI: 10.1038/ijo.2017.170] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 06/16/2017] [Accepted: 07/14/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND/OBJECTIVES In obesity, improved muscle insulin sensitivity following exercise training has been linked to the lowering of diacylglycerol (DAG) and ceramide concentrations. Little is known, however, about how improved insulin action with exercise training in obese individuals relates to lipid droplet (LD) adaptations in skeletal muscle. In this study we investigated the hypothesis that short-term sprint interval training (SIT) and moderate-intensity continuous training (MICT) in obese individuals would increase perilipin (PLIN) expression, increase the proportion of LDs in contact with mitochondria and reduce muscle concentrations of DAGs and ceramides. METHODS Sixteen sedentary obese males performed 4 weeks of either SIT (4-7 × 30 s sprints at 200% Wmax, 3 days week) or MICT (40-60 min cycling at ~65% VO2peak, 5 days per week), and muscle biopsies were obtained pre- and post-training. RESULTS Training increased PLIN2 (SIT 90%, MICT 68%) and PLIN5 (SIT 47%, MICT 34%) expression in type I fibres only, and increased PLIN3 expression in both type I (SIT 63%, MICT 67%) and type II fibres (SIT 70%, MICT 160%) (all P<0.05). Training did not change LD content but increased the proportion of LD in contact with mitochondria (SIT 12%, MICT 21%, P<0.01). Ceramides were reduced following training (SIT -10%, MICT -7%, P<0.05), but DAG was unchanged. No training × group interactions were observed for any variables. CONCLUSIONS These results confirm the hypothesis that SIT and MICT results in remodelling of LDs and lowers ceramide concentrations in skeletal muscle of sedentary obese males.
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Gemmink A, Goodpaster BH, Schrauwen P, Hesselink MKC. Intramyocellular lipid droplets and insulin sensitivity, the human perspective. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1242-1249. [PMID: 28739280 DOI: 10.1016/j.bbalip.2017.07.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 11/19/2022]
Abstract
Skeletal muscle can store excess fat as subcellular lipid droplets (LDs). While originally viewed as uninteresting static balls of triacylglycerol, it is now clear that myocellular LDs play an active role in myocellular (patho)physiology. In this review we aim to discuss the role of LDs in muscle cell insulin sensitivity and identify parameters which appear to affect this relationship. Moreover, we discuss the application of novel tools permitting detailed examination of these parameters. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Anne Gemmink
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Bret H Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Orlando, FL, USA
| | - Patrick Schrauwen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Matthijs K C Hesselink
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands.
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30
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Chow LS, Mashek DG, Wang Q, Shepherd SO, Goodpaster BH, Dubé JJ. Effect of acute physiological free fatty acid elevation in the context of hyperinsulinemia on fiber type-specific IMCL accumulation. J Appl Physiol (1985) 2017; 123:71-78. [PMID: 28450549 DOI: 10.1152/japplphysiol.00209.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/22/2017] [Accepted: 04/22/2017] [Indexed: 12/22/2022] Open
Abstract
It is well described that increasing free fatty acids (FFAs) to high physiological levels reduces insulin sensitivity. In sedentary humans, intramyocellular lipid (IMCL) is inversely related to insulin sensitivity. Since muscle fiber composition affects muscle metabolism, whether FFAs induce IMCL accumulation in a fiber type-specific manner remains unknown. We hypothesized that in the setting of acute FFA elevation by lipid infusion within the context of a hyperinsulinemic-euglycemic clamp, IMCL will preferentially accumulate in type 1 fibers. Normal-weight participants (n = 57, mean ± SE: age 24 ± 0.6 yr, BMI 22.2 ± 0.3 kg/m2) who were either endurance trained or sedentary by self-report were recruited from the University of Minnesota (n = 31, n = 15 trained) and University of Pittsburgh (n = 26, n = 14 trained). All participants underwent a hyperinsulinemic-euglycemic clamp in the context of a 6-h infusion of either lipid or glycerol control. A vastus lateralis muscle biopsy was obtained at baseline and end-infusion (6 h). The muscle biopsies were processed and analyzed at the University of Pittsburgh for fiber type-specific IMCL accumulation by Oil-Red-O staining. Regardless of training status, acute elevation of FFAs to high physiological levels (~400-600 meq/l) increased IMCL preferentially in type 1 fibers (+35 ± 11% compared with baseline, +29 ± 11% compared with glycerol control: P < 0.05). The increase in IMCL correlated with a decline in insulin sensitivity as measured by the hyperinsulinemic-euglycemic clamp (r = -0.32, P < 0.01) independent of training status. Regardless of training status, increase of FFAs to a physiological range within the context of hyperinsulinemia shows preferential IMCL accumulation in type 1 fibers.NEW & NOTEWORTHY This novel human study examined the effects of FFA elevation in the setting of hyperinsulinemia on accumulation of fat in specific types of muscle fibers. Within the context of the hyperinsulinemic-euglycemic clamp, we found that an increase of FFAs to a physiological range sufficient to reduce insulin sensitivity is associated with preferential IMCL accumulation in type 1 fibers.
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Affiliation(s)
- Lisa S Chow
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota;
| | - Douglas G Mashek
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Qi Wang
- Division of Biostatistics, School of Public Health, Minneapolis, Minnesota
| | - Sam O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; and
| | - Bret H Goodpaster
- Department of Endocrinology, University of Pittsburgh Schools of the Health Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John J Dubé
- Department of Endocrinology, University of Pittsburgh Schools of the Health Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
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31
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Intramyocellular lipid content and lipogenic gene expression responses following a single bout of resistance type exercise differ between young and older men. Exp Gerontol 2017; 93:36-45. [PMID: 28385599 DOI: 10.1016/j.exger.2017.03.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/07/2017] [Accepted: 03/28/2017] [Indexed: 11/21/2022]
Abstract
The aim of this study was to examine the temporal relationship between intramyocellular lipid (IMCL) content and the expression of genes associated with IMCL turnover, fat metabolism, and inflammation during recovery from an acute bout of resistance type exercise in old versus young men. Seven healthy young (23±2years, 77.2±2.9kg) and seven healthy older (72±1years, 79.3±4.9kg) males performed a single bout of resistance exercise involving 6 sets of 10 repetitions of leg press and 6 sets of 10 repetitions of leg extension at 75% one-repetition maximum (1-RM). Muscle biopsy samples were obtained before and 12, 24 and 48h after the completion of exercise and analysed for IMCL content and the expression of 48 genes. The subjects refrained from further heavy physical exercise and consumed a standardized diet for the entire experimental period. The IMCL content was ~2-fold higher at baseline and 12h post-exercise in old compared with young individuals. However, no differences between groups were apparent after 48h of recovery. There was higher expression of genes involved in fatty acid synthesis (FASN and PPARγ) during the first 24h of recovery. Differential responses to exercise were observed between groups for a number of genes indicating increased inflammatory response (IL6, IkBalpha, CREB1) and impaired fat metabolism and TCA cycle (LPL, ACAT1, SUCLG1) in older compared with younger individuals. A singe bout of resistance type exercise leads to molecular changes in skeletal muscle favouring reduced lipid oxidation, increased lipogenesis, and exaggerated inflammation during post-exercise recovery in the older compared with younger individuals, which may be indicative of a blunted response of IMCL turnover with ageing.
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Dubé JJ, Broskey NT, Despines AA, Stefanovic-Racic M, Toledo FGS, Goodpaster BH, Amati F. Muscle Characteristics and Substrate Energetics in Lifelong Endurance Athletes. Med Sci Sports Exerc 2017; 48:472-80. [PMID: 26460630 DOI: 10.1249/mss.0000000000000789] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE The goal of this study was to explore the effect of lifelong aerobic exercise (i.e., chronic training) on skeletal muscle substrate stores (intramyocellular triglyceride [IMTG] and glycogen), skeletal muscle phenotypes, and oxidative capacity (ox), in older endurance-trained master athletes (OA) compared with noncompetitive recreational younger (YA) athletes matched by frequency and mode of training. METHODS Thirteen OA (64.8 ± 4.9 yr) exercising 5 times per week or more were compared with 14 YA (27.8 ± 4.9 yr) males and females. IMTG, glycogen, fiber types, succinate dehydrogenase, and capillarization were measured by immunohistochemistry in vastus lateralis biopsies. Fat-ox and carbohydrate (CHO)-ox were measured by indirect calorimetry before and after an insulin clamp and during a cycle ergometer graded maximal test. RESULTS V˙O2peak was lower in OA than YA. The OA had greater IMTG in all fiber types and lower glycogen stores than YA. This was reflected in greater proportion of type I and less type II fibers in OA. Type I fibers were similar in size, whereas type II fibers were smaller in OA compared with YA. Both groups had similar succinate dehydrogenase content. Numbers of capillaries per fiber were reduced in OA but with a higher number of capillaries per area. Metabolic flexibility and insulin sensitivity were similar in both groups. Exercise metabolic efficiency was higher in OA. At moderate exercise intensities, carbohydrate-ox was lower in OA but with similar Fat-ox. CONCLUSIONS Lifelong exercise is associated with higher IMTG content in all muscle fibers and higher metabolic efficiency during exercise that are not explained by differences in muscle fibers types and other muscle characteristics when comparing older with younger athletes matched by exercise mode and frequency.
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Affiliation(s)
- John J Dubé
- 1Division of Endocrinology and Metabolism, Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA; and 2Department of Physiology & Institute of Sport Sciences, School of Biology and Medicine, University of Lausanne, Lausanne, SWITZERLAND
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Schrauwen P, van Marken Lichtenbelt WD. Combatting type 2 diabetes by turning up the heat. Diabetologia 2016; 59:2269-2279. [PMID: 27591854 PMCID: PMC5506100 DOI: 10.1007/s00125-016-4068-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/22/2016] [Indexed: 12/21/2022]
Abstract
In our westernised society, the level of physical activity is low. Interventions that increase energy expenditure are generally associated with an improvement in metabolic health. Exercise and exercise training increase energy metabolism and are considered to be among the best strategies for prevention of type 2 diabetes mellitus. More recently, cold exposure has been suggested to have a therapeutic value in type 2 diabetes. At a cellular level, there is evidence that increasing the turnover of cellular substrates such as fatty acids is associated with preventive effects against lipid-induced insulin resistance. Cellular energy sensors may underlie the effects linking energy turnover with metabolic health effects. Here we review data supporting the hypothesis that increasing energy and substrate turnover has beneficial effects on insulin sensitivity and should be considered a target for the prevention and treatment of type 2 diabetes.
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Affiliation(s)
- Patrick Schrauwen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, P.O. BOX 616, 6200MD, Maastricht, the Netherlands.
| | - Wouter D van Marken Lichtenbelt
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, P.O. BOX 616, 6200MD, Maastricht, the Netherlands
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van Hall G. The Physiological Regulation of Skeletal Muscle Fatty Acid Supply and Oxidation During Moderate-Intensity Exercise. Sports Med 2016; 45 Suppl 1:S23-32. [PMID: 26553490 PMCID: PMC4672010 DOI: 10.1007/s40279-015-0394-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Energy substrates that are important to the working muscle at moderate intensities are the non-esterified fatty acids (NEFAs) taken up from the circulation and NEFAs originating from lipolysis of the intramuscular triacylglycerol (IMTAG). Moreover, NEFA from lipolysis via lipoprotein lipase (LPL) in the muscle of the very-low-density lipoproteins and in the (semi) post-prandial state chylomicrons may also contribute. In this review, the NEFA fluxes and oxidation by skeletal muscle during prolonged moderate-intensity exercise are described in terms of the integration of physiological systems. Steps involved in the regulation of the active muscle NEFA uptake include (1) increased energy demand; (2) delivery of NEFA to the muscle; (3) transport of NEFA into the muscle by NEFA transporters; and (4) activation of the NEFAs and either oxidation or re-esterification into IMTAG. The increased metabolic demand of the exercising muscle is the main driving force for all physiological regulatory processes. It elicits functional hyperemia, increasing the recruitment of capillaries and muscle blood flow resulting in increased NEFA delivery and accessibility to NEFA transporters and LPL. It also releases epinephrine that augments adipose tissue NEFA release and thereby NEFA delivery to the active muscle. Moreover, NEFA transporters translocate to the plasma membrane, further increasing the NEFA uptake. The majority of the NEFAs taken up by the active muscle is oxidized and a minor portion is re-esterified to IMTAG. Net IMTAG lipolysis occurs; however, the IMTAG contribution to total fat oxidation is rather limited compared to plasma-derived NEFA oxidation, suggesting a complex role and regulation of IMTAG utilization.
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Affiliation(s)
- Gerrit van Hall
- Clinical Metabolomics Core Facility, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Rigshospitalet, University of Copenhagen, Section 7652, 9 Blegdamsvej, 2100, Copenhagen, Denmark.
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35
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Perreault L, Starling AP, Glueck D, Brozinick JT, Sanders P, Siddall P, Kuo MS, Dabelea D, Bergman BC. Biomarkers of Ectopic Fat Deposition: The Next Frontier in Serum Lipidomics. J Clin Endocrinol Metab 2016; 101:176-82. [PMID: 26574956 PMCID: PMC4701843 DOI: 10.1210/jc.2015-3213] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
CONTEXT Strong evidence suggests that ectopic fat rather than fat mass per se drives risk for type 2 diabetes. Nonetheless, biomarkers of ectopic fat have gone unexplored. OBJECTIVE To determine the utility of serum lipidomics to predict ectopic lipid deposition. DESIGN Cross-sectional. SETTING The Clinical Translational Research Center at the University of Colorado Anschutz Medical Campus. PARTICIPANTS Endurance-trained athletes (n = 15, 41 ± 0.9 y old; body mass index 24 ± 0.6 kg/m(2)) and obese people with or without type 2 diabetes (n = 29, 42 ± 1.4 y old; body mass index 32 ± 2.5 kg/m(2)). INTERVENTION Blood sampling and skeletal muscle biopsy. MAIN OUTCOME MEASURES Multivariable models determined the ability of serum lipids to predict intramuscular (im) lipid accumulation of triacylglycerol (TAG), diacylglycerol (DAG), and ceramide (liquid chromatography tandem mass spectroscopy). RESULTS Among people with obesity, serum ganglioside C22:0 and lactosylceramide C14:0 predicted muscle TAG (overall model R(2) = 0.48), whereas serum DAG C36:1 and free fatty acid (FFA) C18:4 were strong predictors of muscle DAG (overall model R(2) = 0.77), as were serum TAG C58:5, FFA C14:2 and C14:3, phosphotidylcholine C38:1, and cholesterol ester C24:1 to predict muscle ceramide (overall model R(2) = 0.85). Among endurance-trained athletes, serum FFA C14:1 and sphingosine were significant predictors of muscle TAG (overall model R(2) = 0.81), whereas no models could predict intramuscular DAG or ceramide in this group. CONCLUSIONS Different serum lipids predict intramuscular TAG accumulation in obese people vs athletes. The ability of serum lipidomics to predict intramuscular DAG and ceramide in insulin-resistant humans may prove a new biomarker to determine risk for diabetes.
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Affiliation(s)
- Leigh Perreault
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Anne P Starling
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Deborah Glueck
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Joseph T Brozinick
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Phil Sanders
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Parker Siddall
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Ming Shang Kuo
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Dana Dabelea
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
| | - Bryan C Bergman
- Division of Endocrinology, Metabolism and Diabetes (L.P., B.C.B.), University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Department of Epidemiology (L.P., A.P.S., D.D.), Colorado School of Public Heath, Aurora, Colorado 80045; Department of Biostatistics and Informatics (D.G.), Colorado School of Public Health, Aurora, Colorado 80045; and Eli Lilly and Company (J.T.B., P.Sa., P.Si., M.S.K.), Indianapolis, Indiana 46285
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Søgaard D, Østergård T, Blachnio-Zabielska AU, Baranowski M, Vigelsø AH, Andersen JL, Dela F, Helge JW. Training Does Not Alter Muscle Ceramide and Diacylglycerol in Offsprings of Type 2 Diabetic Patients Despite Improved Insulin Sensitivity. J Diabetes Res 2016; 2016:2372741. [PMID: 27777958 PMCID: PMC5061984 DOI: 10.1155/2016/2372741] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/06/2016] [Accepted: 09/08/2016] [Indexed: 01/08/2023] Open
Abstract
Ceramide and diacylglycerol (DAG) may be involved in the early phase of insulin resistance but data are inconsistent in man. We evaluated if an increase in insulin sensitivity after endurance training was accompanied by changes in these lipids in skeletal muscle. Nineteen first-degree type 2 diabetes Offsprings (Offsprings) (age: 33.1 ± 1.4 yrs; BMI: 26.4 ± 0.4 kg/m2) and sixteen matched Controls (age: 31.3 ± 1.5 yrs; BMI: 25.3 ± 0.7 kg/m2) performed 10 weeks of endurance training three times a week at 70% of VO2max on a bicycle ergometer. Before and after the intervention a hyperinsulinemic-euglycemic clamp and VO2max test were performed and muscle biopsies obtained. Insulin sensitivity was significantly lower in Offsprings compared to control subjects (p < 0.01) but improved in both groups after 10 weeks of endurance training (Off: 17 ± 6%; Con: 12 ± 9%, p < 0.01). The content of muscle ceramide, DAG, and their subspecies were similar between groups and did not change in response to the endurance training except for an overall reduction in C22:0-Cer (p < 0.05). Finally, the intervention induced an increase in AKT protein expression (Off: 27 ± 11%; Con: 20 ± 24%, p < 0.05). This study showed no relation between insulin sensitivity and ceramide or DAG content suggesting that ceramide and DAG are not major players in the early phase of insulin resistance in human muscle.
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Affiliation(s)
- Ditte Søgaard
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Ditte Søgaard:
| | - Torben Østergård
- Department of Endocrinology and Diabetes M, Aarhus University Hospital, Aarhus Sygehus, Aarhus, Denmark
- Department of Internal Medicine, Regional Hospital Viborg, Viborg, Denmark
| | | | - Marcin Baranowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Andreas Hansen Vigelsø
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Flemming Dela
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jørn Wulff Helge
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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37
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Bergman BC, Brozinick JT, Strauss A, Bacon S, Kerege A, Bui HH, Sanders P, Siddall P, Kuo MS, Perreault L. Serum sphingolipids: relationships to insulin sensitivity and changes with exercise in humans. Am J Physiol Endocrinol Metab 2015; 309:E398-408. [PMID: 26126684 PMCID: PMC4537923 DOI: 10.1152/ajpendo.00134.2015] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 06/25/2015] [Indexed: 01/15/2023]
Abstract
Ceramides and sphingolipids are a family of lipid molecules that circulate in serum and accumulate in skeletal muscle, promoting insulin resistance. Plasma ceramide and dihydroceramide are related to insulin resistance, yet less is known regarding other ceramide and sphingolipid species. Despite its association with insulin sensitivity, chronic endurance exercise training does not change plasma ceramide and sphingolipid content, with little known regarding a single bout of exercise. We measured basal relationships and the effect of acute exercise (1.5 h at 50% V̇o2 max) and recovery on serum ceramide and sphingolipid content in sedentary obese individuals, endurance-trained athletes, and individuals with type 2 diabetes (T2D). Basal serum C18:0, C20:0, and C24:1 ceramide and C18:0 and total dihydroceramide were significantly higher in T2D and, along with C16:0 ceramide and C18:0 sphingomyelin, correlated positively with insulin resistance. Acute exercise significantly increased serum ceramide, glucosylceramide, and GM3 gangliosides, which largely decreased to basal values in recovery. Sphingosine 1-phosphate and sphingomyelin did not change during exercise but decreased below basal values in recovery. Serum C16:0 and C18:0 ceramide and C18:0 sphingomyelin, but not the total concentrations of either of them, were positively correlated with markers of muscle NF-κB activation, suggesting that specific species activate intracellular inflammation. Interestingly, a subset of sphingomyelin species, notably C14:0, C22:3, and C24:4 species, was positively associated with insulin secretion and glucose tolerance. Together, these data show that unique ceramide and sphingolipid species associate with either protective or deleterious features for diabetes and could provide novel therapeutic targets for the future.
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Affiliation(s)
- Bryan C Bergman
- University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
| | | | - Allison Strauss
- University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
| | - Samantha Bacon
- University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
| | - Anna Kerege
- University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
| | | | | | | | | | - Leigh Perreault
- University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
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38
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Ritter O, Jelenik T, Roden M. Lipid-mediated muscle insulin resistance: different fat, different pathways? J Mol Med (Berl) 2015; 93:831-43. [PMID: 26108617 DOI: 10.1007/s00109-015-1310-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 05/27/2015] [Accepted: 06/12/2015] [Indexed: 12/22/2022]
Abstract
Increased dietary fat intake and lipolysis result in excessive lipid availability, which relates to impaired insulin sensitivity. Over the last years, several mechanisms possibly underlying lipid-mediated insulin resistance evolved. Lipid intermediates such as diacylglycerols (DAG) associate with changes in insulin sensitivity in many models. DAG activate novel protein kinase C (PKC) isoforms followed by inhibitory serine phosphorylation of insulin receptor substrate 1 (IRS1). Activation of Toll-like receptor 4 (TLR4) raises another lipid class, ceramides (CER), which induce pro-inflammatory pathways and lead to inhibition of Akt phosphorylation. Inhibition of glucosylceramide and ganglioside synthesis results in improved insulin sensitivity and increased activatory tyrosine phosphorylation of IRS1 in the muscle. Incomplete fat oxidation can increase acylcarnitines (ACC), which in turn stimulate pro-inflammatory pathways. This review analyzed the effects of lipid metabolites on insulin action in skeletal muscle of humans and rodents. Despite the evidence for the association of both DAG and CER with insulin resistance, its causal relevance may differ depending on the subcellular localization and the tested cohorts, e.g., athletes. Nevertheless, recent data indicate that individual lipid species and their degree of fatty acid saturation, particularly membrane and cytosolic C18:2 DAG, specifically activate PKCθ and induce both acute lipid-induced and chronic insulin resistance in humans.
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Affiliation(s)
- Olesja Ritter
- Institute for Clinical Diabetology, German Diabetes Center, c/o Auf'm Hennekamp 65, D-40225, Düsseldorf, Germany
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39
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Thorn SR, Baquero KC, Newsom SA, El Kasmi KC, Bergman BC, Shulman GI, Grove KL, Friedman JE. Early life exposure to maternal insulin resistance has persistent effects on hepatic NAFLD in juvenile nonhuman primates. Diabetes 2014; 63:2702-13. [PMID: 24705404 PMCID: PMC4113070 DOI: 10.2337/db14-0276] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The origins of nonalcoholic fatty liver disease (NAFLD) may lie in early intrauterine exposures. Here we examined the maternal response to chronic maternal high-fat (HF) diet and the impact of postweaning healthy diet on mechanisms for NAFLD development in juvenile nonhuman primate (NHP) offspring at 1 year of age. Pregnant females on HF diet were segregated as insulin resistant (IR; HF+IR) or insulin sensitive (IS; HF+IS) compared with control (CON)-fed mothers. HF+IR mothers have increased body mass, higher triglycerides, and increased placental cytokines. At weaning, offspring were placed on a CON or HF diet. Only offspring from HF+IR mothers had increased liver triglycerides and upregulated pathways for hepatic de novo lipid synthesis and inflammation that was irreversible upon switching to a healthy diet. These juvenile livers also showed a combination of classical and alternatively activated hepatic macrophages and natural killer T cells, in the absence of obesity or insulin resistance. Our findings suggest that maternal insulin resistance, including elevated triglycerides, insulin, and weight gain, initiates dysregulation of the juvenile hepatic immune system and development of de novo lipogenic pathways that persist in vitro and may be an irreversible "first hit" in the pathogenesis of NAFLD in NHP.
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Affiliation(s)
- Stephanie R Thorn
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Karalee C Baquero
- Diabetes, Obesity, and Metabolism, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR
| | - Sean A Newsom
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Karim C El Kasmi
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Bryan C Bergman
- Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Gerald I Shulman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Kevin L Grove
- Diabetes, Obesity, and Metabolism, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR
| | - Jacob E Friedman
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
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40
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Chow LS, Mashek DG, Austin E, Eberly LE, Persson XM, Mashek MT, Seaquist ER, Jensen MD. Training status diverges muscle diacylglycerol accumulation during free fatty acid elevation. Am J Physiol Endocrinol Metab 2014; 307:E124-31. [PMID: 24844260 PMCID: PMC4080147 DOI: 10.1152/ajpendo.00166.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
How endurance training alters muscle lipid metabolism while preserving insulin sensitivity remains unclear. Because acute free fatty acid (FFA) elevation by lipid infusion reduces insulin sensitivity, we hypothesized that training status would alter accumulation of muscle triacylglycerol (TAG), diacylglycerol (DAG), ceramide, and acylcarnitine during acute FFA elevation. Trained (n = 15) and sedentary (n = 13) participants matched for age, sex, and BMI received either a 6-h infusion of lipid (20% Intralipid at 90 ml/h) or glycerol (2.25 g/100 ml at 90 ml/h) during a hyperinsulinemic euglycemic clamp. Muscle biopsies were taken at 0, 120, and 360 min after infusion initiation to measure intramyocellular concentrations of TAG, DAG, ceramides, and acylcarnitines by liquid chromatography-tandem mass spectrometry. Trained participants had a higher Vo2 max and insulin sensitivity than sedentary participants. The lipid infusion produced a comparable elevation of FFA (594 ± 90 μmol/l in trained, 721 ± 30 μmol/l in sedentary, P = 0.4) and a decline in insulin sensitivity (-44.7% trained vs. -47.2% sedentary, P = 0.89). In both groups, lipid infusion increased the linoleic and linolenic acid content of TAG without changing total TAG. In the sedentary group, lipid infusion increased total, oleic, and linoleic acid and linolenic acid content of DAG. Regardless of training status, lipid infusion did not alter total ceramide, saturated ceramide, palmitoyl-carnitine, or oleoyl-carnitine. We conclude that during acute FFA elevation, trained adults have a similar decline in insulin sensitivity with less accumulation of muscle DAG than sedentary adults, suggesting that lipid-induced insulin resistance can occur without elevation of total muscle DAG.
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Affiliation(s)
- Lisa S Chow
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota;
| | - Douglas G Mashek
- Department of Food Science and Nutrition, University of Minnesota, Minneapolis, Minnesota
| | - Erin Austin
- Division of Biostatistics, University of Minnesota, Minneapolis, Minnesota; and
| | - Lynn E Eberly
- Division of Biostatistics, University of Minnesota, Minneapolis, Minnesota; and
| | - Xuan-Mai Persson
- Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Mara T Mashek
- Department of Food Science and Nutrition, University of Minnesota, Minneapolis, Minnesota
| | | | - Michael D Jensen
- Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota
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41
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Increased Stearoyl-CoA Desaturase Index and Triglyceride Content in the Liver of Rats after a Single Bout of Swimming Exercise. Biosci Biotechnol Biochem 2014; 76:1350-5. [DOI: 10.1271/bbb.120095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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42
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Sparks LM, Bosma M, Brouwers B, van de Weijer T, Bilet L, Schaart G, Moonen-Kornips E, Eichmann TO, Lass A, Hesselink MK, Schrauwen P. Reduced incorporation of fatty acids into triacylglycerol in myotubes from obese individuals with type 2 diabetes. Diabetes 2014; 63:1583-1593. [PMID: 24487026 PMCID: PMC4023412 DOI: 10.2337/db13-1123] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Altered skeletal muscle lipid metabolism is a hallmark feature of type 2 diabetes (T2D). We investigated muscle lipid turnover in T2D versus BMI-matched control subjects (controls) and examined whether putative in vivo differences would be preserved in the myotubes. Male obese T2D individuals (n = 6) and BMI-matched controls (n = 6) underwent a hyperinsulinemic-euglycemic clamp, VO2max test, dual-energy X-ray absorptiometry scan, underwater weighing, and muscle biopsy of the vastus lateralis. (14)C-palmitate and (14)C-oleate oxidation rates and incorporation into lipids were measured in muscle tissue as well as in primary myotubes. Palmitate oxidation (controls: 0.99 ± 0.17 nmol/mg protein; T2D: 0.53 ± 0.07 nmol/mg protein; P = 0.03) and incorporation of fatty acids (FAs) into triacylglycerol (TAG) (controls: 0.45 ± 0.13 nmol/mg protein; T2D: 0.11 ± 0.02 nmol/mg protein; P = 0.047) were significantly reduced in muscle homogenates of T2D. These reductions were not retained for palmitate oxidation in primary myotubes (P = 0.38); however, incorporation of FAs into TAG was lower in T2D (P = 0.03 for oleate and P = 0.11 for palmitate), with a strong correlation of TAG incorporation between muscle tissue and primary myotubes (r = 0.848, P = 0.008). The data indicate that the ability to incorporate FAs into TAG is an intrinsic feature of human muscle cells that is reduced in individuals with T2D.
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Affiliation(s)
- Lauren M. Sparks
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL
| | - Madeleen Bosma
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Bram Brouwers
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Tineke van de Weijer
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Lena Bilet
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Gert Schaart
- Department of Human Movement Sciences, NUTRIM—School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Esther Moonen-Kornips
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | | | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Matthijs K.C. Hesselink
- Department of Human Movement Sciences, NUTRIM—School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Patrick Schrauwen
- Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
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43
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Bosma M. Lipid homeostasis in exercise. Drug Discov Today 2014; 19:1019-23. [PMID: 24632001 DOI: 10.1016/j.drudis.2014.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 03/06/2014] [Indexed: 01/08/2023]
Abstract
Fatty acids (FA) are essential energy substrates during endurance exercise. In addition to systemic supply, intramyocellular neutral lipids form an important source of FA for the working muscle. Endurance exercise training is associated with an increased reliance on lipids as a fuel source, has systemic lipid-lowering effects and results in a remodeling of skeletal muscle lipid metabolism toward increased oxidation, neutral lipid storage and turnover. Interestingly, recent studies have indicated common exercise-induced regulatory pathways for genes involved in skeletal muscle mitochondrial oxidative metabolism and lipid droplet (LD) dynamics. In this review, I discuss lipid homeostasis during acute exercise and adaptations in lipid metabolism upon exercise training in the light of recent advances in the field.
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Affiliation(s)
- Madeleen Bosma
- Department of Cell and Molecular Biology, Karolinska Institutet, PO Box 285, SE-171 77 Stockholm, Sweden.
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44
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Bajpeyi S, Myrland CK, Covington JD, Obanda D, Cefalu WT, Smith SR, Rustan AC, Ravussin E. Lipid in skeletal muscle myotubes is associated to the donors' insulin sensitivity and physical activity phenotypes. Obesity (Silver Spring) 2014; 22:426-34. [PMID: 23818429 PMCID: PMC3883809 DOI: 10.1002/oby.20556] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 06/17/2013] [Indexed: 12/21/2022]
Abstract
OBJECTIVE This study investigated the relationship between in vitro lipid content in myotubes and in vivo whole body phenotypes of the donors such as insulin sensitivity, intramyocellular lipids (IMCL), physical activity, and oxidative capacity. DESIGN AND METHODS Six physically active donors were compared to six sedentary lean and six T2DM. Lipid content was measured in tissues and myotubes by immunohistochemistry. Ceramides, triacylglycerols, and diacylglycerols (DAGs) were measured by LC-MS-MS and GC-FID. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp (80 mU min⁻¹ m⁻²), maximal mitochondrial capacity (ATPmax) by ³¹P-MRS, physical fitness by VO₂max and physical activity level (PAL) by accelerometers. RESULTS Myotubes cultured from physically active donors had higher lipid content (0.047 ± 0.003 vs. 0.032 ± 0.001 and 0.033 ± 0.001AU; P < 0.001) than myotubes from lean and T2DM donors. Lipid content in myotubes was not associated with IMCL in muscle tissue but importantly, correlated with in vivo measures of ATPmax (r = 0.74; P < 0.001), insulin sensitivity (r = 0.54; P < 0.05), type-I fibers (r = 0.50; P < 0.05), and PAL (r = 0.92; P < 0.0001). DAGs and ceramides in myotubes were inversely associated with insulin sensitivity (r = -0.55, r = -0.73; P < 0.05) and ATPmax (r = -0.74, r = -0.85; P < 0.01). CONCLUSIONS These results indicate that cultured human myotubes can be used in mechanistic studies to study the in vitro impact of interventions on phenotypes such as mitochondrial capacity, insulin sensitivity, and physical activity.
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MESH Headings
- Adult
- Biopsy
- Body Mass Index
- Cells, Cultured
- Ceramides/metabolism
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Diglycerides/metabolism
- Female
- Humans
- Insulin Resistance
- Lipid Metabolism
- Male
- Mitochondria, Muscle/metabolism
- Mitochondria, Muscle/pathology
- Motor Activity
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/pathology
- Obesity, Morbid/complications
- Oxidative Phosphorylation
- Oxygen Consumption
- Physical Fitness
- Triglycerides/metabolism
- Young Adult
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Affiliation(s)
- Sudip Bajpeyi
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Cassandra K. Myrland
- Dept. of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Jeffrey D. Covington
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Diana Obanda
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - William T. Cefalu
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Steven R. Smith
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital / Sanford-Burnham Medical Research Institute, 301 E. Princeton St. Orlando, FL 32804
| | - Arild C. Rustan
- Dept. of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Eric Ravussin
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
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45
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Badin PM, Langin D, Moro C. Dynamics of skeletal muscle lipid pools. Trends Endocrinol Metab 2013; 24:607-15. [PMID: 23988586 DOI: 10.1016/j.tem.2013.08.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/22/2013] [Accepted: 08/03/2013] [Indexed: 11/20/2022]
Abstract
Intramyocellular triacylglycerol (IMTG) is emerging as an important energy fuel source during muscle contraction and are adaptively increased in response to exercise, without adverse physiological effects. Paradoxically, elevated IMTG content in obese and type 2 diabetics has been linked to insulin resistance, highlighting the importance of IMTG pools in physiology and pathology. Two separate views suggest that IMTG dynamics are determinant for skeletal muscle fat oxidation, and that disruption of IMTG dynamics facilitates the accumulation of lipotoxic intermediates such as diacylglycerols and ceramides that interfere with insulin signaling. Thus, understanding the factors that control IMTG dynamics is crucial. Here we discuss recent literature describing the regulation of IMTG pools with a particular emphasis on lipases and lipid droplet (LD)-associated proteins.
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Affiliation(s)
- Pierre-Marie Badin
- Obesity Research Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1048, Institute of Metabolic and Cardiovascular Diseases (I2MC), Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
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46
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Stamatikos AD, Paton CM. Role of stearoyl-CoA desaturase-1 in skeletal muscle function and metabolism. Am J Physiol Endocrinol Metab 2013; 305:E767-75. [PMID: 23941875 DOI: 10.1152/ajpendo.00268.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Stearoyl-CoA desaturase-1 (SCD1) converts saturated fatty acids (SFA) into monounsaturated fatty acids and is necessary for proper liver, adipose tissue, and skeletal muscle lipid metabolism. While there is a wealth of information regarding SCD1 expression in the liver, research on its effect in skeletal muscle is scarce. Furthermore, the majority of information about its role is derived from global knockout mice, which are known to be hypermetabolic and fail to accumulate SCD1's substrate, SFA. We now know that SCD1 expression is important in regulating lipid bilayer fluidity, increasing triglyceride formation, and enabling lipogenesis and may protect against SFA-induced lipotoxicity. Exercise has been shown to increase SCD1 expression, which may contribute to an increase in intramyocellular triglyceride at the expense of free fatty acids and diacylglycerol. This review is intended to define the role of SCD1 in skeletal muscle and discuss the potential benefits of its activity in the context of lipid metabolism, insulin sensitivity, exercise training, and obesity.
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Sieber J, Weins A, Kampe K, Gruber S, Lindenmeyer MT, Cohen CD, Orellana JM, Mundel P, Jehle AW. Susceptibility of podocytes to palmitic acid is regulated by stearoyl-CoA desaturases 1 and 2. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:735-44. [PMID: 23867797 DOI: 10.1016/j.ajpath.2013.05.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 05/14/2013] [Accepted: 05/16/2013] [Indexed: 12/21/2022]
Abstract
Type 2 diabetes mellitus is characterized by dyslipidemia with elevated free fatty acids (FFAs). Loss of podocytes is a hallmark of diabetic nephropathy, and podocytes are highly susceptible to saturated FFAs but not to protective, monounsaturated FFAs. We report that patients with diabetic nephropathy develop alterations in glomerular gene expression of enzymes involved in fatty acid metabolism, including induction of stearoyl-CoA desaturase (SCD)-1, which converts saturated to monounsaturated FFAs. By IHC of human renal biopsy specimens, glomerular SCD-1 induction was observed in podocytes of patients with diabetic nephropathy. Functionally, the liver X receptor agonists TO901317 and GW3965, two known inducers of SCD, increased Scd-1 and Scd-2 expression in cultured podocytes and reduced palmitic acid-induced cell death. Similarly, overexpression of Scd-1 attenuated palmitic acid-induced cell death. The protective effect of TO901317 was associated with a reduction of endoplasmic reticulum stress. It was lost after gene silencing of Scd-1/-2, thereby confirming that the protective effect of TO901317 is mediated by Scd-1/-2. TO901317 also shifted palmitic acid-derived FFAs into biologically inactive triglycerides. In summary, SCD-1 up-regulation in diabetic nephropathy may be part of a protective mechanism against saturated FFA-derived toxic metabolites that drive endoplasmic reticulum stress and podocyte death.
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Affiliation(s)
- Jonas Sieber
- Laboratory of Molecular Nephrology, Department of Biomedicine, University Hospital, Basel, Switzerland
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Therkelsen KE, Pedley A, Speliotes EK, Massaro JM, Murabito J, Hoffmann U, Fox CS. Intramuscular fat and associations with metabolic risk factors in the Framingham Heart Study. Arterioscler Thromb Vasc Biol 2013; 33:863-70. [PMID: 23349188 DOI: 10.1161/atvbaha.112.301009] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Intramuscular fat accumulates between muscle fibers or within muscle cells. We investigated the association of intramuscular fat with other ectopic fat deposits and metabolic risk factors. APPROACH AND RESULTS Participants (n=2945; 50.2% women; mean age 50.8 years) from the Framingham Heart Study underwent multidetector computed tomography scanning of the abdomen. Regions of interest were placed on the left and right paraspinous muscle, and the muscle attenuation (MA) in Hounsfield units was averaged. We examined the association between MA and metabolic risk factors in multivariable models, and additionally adjusted for body mass index (BMI) and visceral adipose tissue (VAT) in separate models. MA was associated with dysglycemia, dyslipidemia, and hypertension in both sexes. In women, per standard deviation decrease in MA, there was a 1.34 (95% confidence interval, 1.10-1.64) increase in the odds of diabetes mellitus, a 1.40 (95% confidence interval, 1.22-1.61) increase in the odds of high triglycerides, and a 1.29 (95% confidence interval, 1.12-1.48) increase in the odds of hypertension. However, none of these associations persisted after adjustment for BMI or VAT. In men, we observed similar patterns for most risk factors. The exception was metabolic syndrome, which retained association in women even after adjustment for BMI and VAT, and low high density lipoprotein and high triglycerides in men, whose associations also persisted after adjustment for BMI and VAT. CONCLUSIONS MA was associated with metabolic risk factors, but most of these associations were lost after adjustment for BMI or VAT. However, a unique association remained for metabolic syndrome in women and lipids in men.
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Zhang XJ, Wang L, Tuvdendorj D, Wu Z, Rodriguez NA, Herndon DN, Wolfe RR. Acute hyperinsulinemia and reduced plasma free fatty acid levels decrease intramuscular triglyceride synthesis. Metabolism 2013; 62:44-51. [PMID: 22898252 PMCID: PMC3518684 DOI: 10.1016/j.metabol.2012.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/17/2012] [Accepted: 06/05/2012] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To investigate the effect of acute hyperinsulinemia and the resulting decrease in plasma free fatty acid (FFA) concentrations on intramuscular TG synthesis. MATERIALS/METHODS U-(13)C(16)-palmitate was infused for 3 h in anesthetized rabbits after overnight food deprivation. Arterial blood and leg muscle were sampled during the tracer infusion. Plasma samples were analyzed for free and TG-bound palmitate enrichments and concentrations. The enrichments and concentrations of palmitoyl-CoA and palmitoyl-carnitine as well as the enrichment of palmitate bound to TG were measured in muscle samples. Fractional synthetic rate (FSR) of intramuscular TG was calculated using the tracer incorporation method. The rabbits were divided into a control group and a hyperinsulinemic euglycemic clamp group. Insulin infusion decreased the rate of appearance of plasma free palmitate (2.00±0.15 vs 0.68±0.20 μmol⋅kg(-1)⋅min(-1); P<.001), decreased plasma FFA concentration (327±61 vs 72±25 nmol/mL; P<.01), decreased the total concentration of intramuscular fatty acyl-CoA plus fatty acyl-carnitine (12.1±1.6 vs 7.0±0.7 nmol/g; P<.05), and decreased intramuscular TG FSR (0.48±0.05 vs 0.21±0.06%/h; P<.01) in comparison with the control group. Intramuscular TG FSR was correlated (P<.01) with both plasma FFA concentrations and intramuscular fatty acyl-CoA concentrations. CONCLUSIONS Fatty acid availability is a determinant of intramuscular TG synthesis. Insulin infusion decreases plasma and intramuscular fatty acid availability and thereby decreases TG synthesis.
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Affiliation(s)
- Xiao-jun Zhang
- Metabolism Unit, Shriners Hospital for Children, University of Texas Medical Branch, Galveston, TX 77550, USA
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77550, USA
| | - Lijian Wang
- Metabolism Unit, Shriners Hospital for Children, University of Texas Medical Branch, Galveston, TX 77550, USA
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77550, USA
| | - Demidmaa Tuvdendorj
- Metabolism Unit, Shriners Hospital for Children, University of Texas Medical Branch, Galveston, TX 77550, USA
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77550, USA
| | - Zhanpin Wu
- Metabolism Unit, Shriners Hospital for Children, University of Texas Medical Branch, Galveston, TX 77550, USA
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77550, USA
| | - Noe A. Rodriguez
- Metabolism Unit, Shriners Hospital for Children, University of Texas Medical Branch, Galveston, TX 77550, USA
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77550, USA
| | - David N. Herndon
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77550, USA
| | - Robert R. Wolfe
- University of Arkansas for Medical Sciences, Geriatrics, 4301 West Markham Street, Little Rock, AR 72205, USA
- Corresponding Author: Robert R. Wolfe, University of Arkansas for Medical Sciences, 4301 West Markham Street, Slot 806, Little Rock, AR 72205-7199, Phone 501-526-5709, Fax 501-686-8025,
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Hodson L, Fielding BA. Stearoyl-CoA desaturase: rogue or innocent bystander? Prog Lipid Res 2013; 52:15-42. [DOI: 10.1016/j.plipres.2012.08.002] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/27/2012] [Accepted: 08/27/2012] [Indexed: 02/07/2023]
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