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Mäkinen S, Sree S, Ala-Nisula T, Kultalahti H, Koivunen P, Koistinen HA. Activation of the hypoxia-inducible factor pathway by roxadustat improves glucose metabolism in human primary myotubes from men. Diabetologia 2024; 67:1943-1954. [PMID: 38814443 PMCID: PMC11410918 DOI: 10.1007/s00125-024-06185-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 04/19/2024] [Indexed: 05/31/2024]
Abstract
AIMS/HYPOTHESIS Hypoxia-inducible factor prolyl 4-hydroxylase (HIF-P4H) enzymes regulate adaptive cellular responses to low oxygen concentrations. Inhibition of HIF-P4Hs leads to stabilisation of hypoxia-inducible factors (HIFs) and activation of the HIF pathway affecting multiple biological processes to rescue cells from hypoxia. As evidence from animal models suggests that HIF-P4H inhibitors could be used to treat metabolic disorders associated with insulin resistance, we examined whether roxadustat, an HIF-P4H inhibitor approved for the treatment of renal anaemia, would have an effect on glucose metabolism in primary human myotubes. METHODS Primary skeletal muscle cell cultures, established from biopsies of vastus lateralis muscle from men with normal glucose tolerance (NGT) (n=5) or type 2 diabetes (n=8), were treated with roxadustat. Induction of HIF target gene expression was detected with quantitative real-time PCR. Glucose uptake and glycogen synthesis were investigated with radioactive tracers. Glycolysis and mitochondrial respiration rates were measured with a Seahorse analyser. RESULTS Exposure to roxadustat stabilised nuclear HIF1α protein expression in human myotubes. Treatment with roxadustat led to induction of HIF target gene mRNAs for GLUT1 (also known as SLC2A1), HK2, MCT4 (also known as SLC16A4) and HIF-P4H-2 (also known as PHD2 or EGLN1) in myotubes from donors with NGT, with a blunted response in myotubes from donors with type 2 diabetes. mRNAs for LDHA, PDK1 and GBE1 were induced to a similar degree in myotubes from donors with NGT or type 2 diabetes. Exposure of myotubes to roxadustat led to a 1.4-fold increase in glycolytic rate in myotubes from men with NGT (p=0.0370) and a 1.7-fold increase in myotubes from donors with type 2 diabetes (p=0.0044), with no difference between the groups (p=0.1391). Exposure to roxadustat led to a reduction in basal mitochondrial respiration in both groups (p<0.01). Basal glucose uptake rates were similar in myotubes from donors with NGT (20.2 ± 2.7 pmol mg-1 min-1) and type 2 diabetes (25.3 ± 4.4 pmol mg-1 min-1, p=0.4205). Treatment with roxadustat enhanced insulin-stimulated glucose uptake in myotubes from donors with NGT (1.4-fold vs insulin-only condition, p=0.0023). The basal rate of glucose incorporation into glycogen was lower in myotubes from donors with NGT (233 ± 12.4 nmol g-1 h-1) than in myotubes from donors with type 2 diabetes (360 ± 40.3 nmol g-1 h-1, p=0.0344). Insulin increased glycogen synthesis by 1.9-fold (p=0.0025) in myotubes from donors with NGT, whereas roxadustat did not affect their basal or insulin-stimulated glycogen synthesis. Insulin increased glycogen synthesis by 1.7-fold (p=0.0031) in myotubes from donors with type 2 diabetes. While basal glycogen synthesis was unaffected by roxadustat, pretreatment with roxadustat enhanced insulin-stimulated glycogen synthesis in myotubes from donors with type 2 diabetes (p=0.0345). CONCLUSIONS/INTERPRETATION Roxadustat increases glycolysis and inhibits mitochondrial respiration in primary human myotubes regardless of diabetes status. Roxadustat may also improve insulin action on glycogen synthesis in myotubes from donors with type 2 diabetes.
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Affiliation(s)
- Selina Mäkinen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Sreesha Sree
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Tuulia Ala-Nisula
- Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, Oulu Center for Cell-Matrix Research, University of Oulu, Oulu, Finland
| | - Henric Kultalahti
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Peppi Koivunen
- Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, Oulu Center for Cell-Matrix Research, University of Oulu, Oulu, Finland
| | - Heikki A Koistinen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland.
- Department of Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
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Shen J, Wang X, Wang M, Zhang H. Potential molecular mechanism of exercise reversing insulin resistance and improving neurodegenerative diseases. Front Physiol 2024; 15:1337442. [PMID: 38818523 PMCID: PMC11137309 DOI: 10.3389/fphys.2024.1337442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 04/29/2024] [Indexed: 06/01/2024] Open
Abstract
Neurodegenerative diseases are debilitating nervous system disorders attributed to various conditions such as body aging, gene mutations, genetic factors, and immune system disorders. Prominent neurodegenerative diseases include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. Insulin resistance refers to the inability of the peripheral and central tissues of the body to respond to insulin and effectively regulate blood sugar levels. Insulin resistance has been observed in various neurodegenerative diseases and has been suggested to induce the occurrence, development, and exacerbation of neurodegenerative diseases. Furthermore, an increasing number of studies have suggested that reversing insulin resistance may be a critical intervention for the treatment of neurodegenerative diseases. Among the numerous measures available to improve insulin sensitivity, exercise is a widely accepted strategy due to its convenience, affordability, and significant impact on increasing insulin sensitivity. This review examines the association between neurodegenerative diseases and insulin resistance and highlights the molecular mechanisms by which exercise can reverse insulin resistance under these conditions. The focus was on regulating insulin resistance through exercise and providing practical ideas and suggestions for future research focused on exercise-induced insulin sensitivity in the context of neurodegenerative diseases.
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Affiliation(s)
- Jiawen Shen
- Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, Taizhou, China
| | - Xianping Wang
- School of Medicine, Taizhou University, Taizhou, China
| | - Minghui Wang
- College of Sports Medicine, Wuhan Sports University, Wuhan, China
| | - Hu Zhang
- College of Sports Medicine, Wuhan Sports University, Wuhan, China
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Siripoksup P, Cao G, Cluntun AA, Maschek JA, Pearce Q, Brothwell MJ, Jeong MY, Eshima H, Ferrara PJ, Opurum PC, Mahmassani ZS, Peterlin AD, Watanabe S, Walsh MA, Taylor EB, Cox JE, Drummond MJ, Rutter J, Funai K. Sedentary behavior in mice induces metabolic inflexibility by suppressing skeletal muscle pyruvate metabolism. J Clin Invest 2024; 134:e167371. [PMID: 38652544 PMCID: PMC11142742 DOI: 10.1172/jci167371] [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: 11/21/2022] [Accepted: 04/16/2024] [Indexed: 04/25/2024] Open
Abstract
Carbohydrates and lipids provide the majority of substrates to fuel mitochondrial oxidative phosphorylation. Metabolic inflexibility, defined as an impaired ability to switch between these fuels, is implicated in a number of metabolic diseases. Here, we explore the mechanism by which physical inactivity promotes metabolic inflexibility in skeletal muscle. We developed a mouse model of sedentariness, small mouse cage (SMC), that, unlike other classic models of disuse in mice, faithfully recapitulated metabolic responses that occur in humans. Bioenergetic phenotyping of skeletal muscle mitochondria displayed metabolic inflexibility induced by physical inactivity, demonstrated by a reduction in pyruvate-stimulated respiration (JO2) in the absence of a change in palmitate-stimulated JO2. Pyruvate resistance in these mitochondria was likely driven by a decrease in phosphatidylethanolamine (PE) abundance in the mitochondrial membrane. Reduction in mitochondrial PE by heterozygous deletion of phosphatidylserine decarboxylase (PSD) was sufficient to induce metabolic inflexibility measured at the whole-body level, as well as at the level of skeletal muscle mitochondria. Low mitochondrial PE in C2C12 myotubes was sufficient to increase glucose flux toward lactate. We further implicate that resistance to pyruvate metabolism is due to attenuated mitochondrial entry via mitochondrial pyruvate carrier (MPC). These findings suggest a mechanism by which mitochondrial PE directly regulates MPC activity to modulate metabolic flexibility in mice.
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Affiliation(s)
- Piyarat Siripoksup
- Diabetes & Metabolism Research Center
- Department of Physical Therapy and Athletic Training
| | - Guoshen Cao
- Diabetes & Metabolism Research Center
- Department of Biochemistry
| | | | - J. Alan Maschek
- Metabolomics Core Research Facility
- Department of Nutrition & Integrative Physiology, and
| | | | - Marisa J. Brothwell
- Diabetes & Metabolism Research Center
- Department of Nutrition & Integrative Physiology, and
| | - Mi-Young Jeong
- Diabetes & Metabolism Research Center
- Department of Biochemistry
| | - Hiroaki Eshima
- Diabetes & Metabolism Research Center
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA
| | - Patrick J. Ferrara
- Diabetes & Metabolism Research Center
- Department of Nutrition & Integrative Physiology, and
| | - Precious C. Opurum
- Diabetes & Metabolism Research Center
- Department of Nutrition & Integrative Physiology, and
| | - Ziad S. Mahmassani
- Diabetes & Metabolism Research Center
- Department of Physical Therapy and Athletic Training
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA
| | - Alek D. Peterlin
- Diabetes & Metabolism Research Center
- Department of Nutrition & Integrative Physiology, and
| | - Shinya Watanabe
- Diabetes & Metabolism Research Center
- Department of Nutrition & Integrative Physiology, and
| | - Maureen A. Walsh
- Diabetes & Metabolism Research Center
- Department of Physical Therapy and Athletic Training
| | - Eric B. Taylor
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - James E. Cox
- Diabetes & Metabolism Research Center
- Department of Biochemistry
- Metabolomics Core Research Facility
| | - Micah J. Drummond
- Diabetes & Metabolism Research Center
- Department of Physical Therapy and Athletic Training
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA
| | - Jared Rutter
- Diabetes & Metabolism Research Center
- Department of Biochemistry
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, USA
| | - Katsuhiko Funai
- Diabetes & Metabolism Research Center
- Department of Physical Therapy and Athletic Training
- Department of Biochemistry
- Department of Nutrition & Integrative Physiology, and
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA
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Omar AK, Li Puma LC, Whitcomb LA, Risk BD, Witt AC, Bruemmer JE, Winger QA, Bouma GJ, Chicco AJ. High-fat diet during pregnancy promotes fetal skeletal muscle fatty acid oxidation and insulin resistance in an ovine model. Am J Physiol Regul Integr Comp Physiol 2023; 325:R523-R533. [PMID: 37642284 PMCID: PMC11178291 DOI: 10.1152/ajpregu.00059.2023] [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: 03/08/2023] [Revised: 08/11/2023] [Accepted: 08/24/2023] [Indexed: 08/31/2023]
Abstract
Maternal diet during pregnancy is associated with offspring metabolic risk trajectory in humans and animal models, but the prenatal origins of these effects are less clear. We examined the effects of a high-fat diet (HFD) during pregnancy on fetal skeletal muscle metabolism and metabolic risk parameters using an ovine model. White-faced ewes were fed a standardized diet containing 5% fat wt/wt (CON), or the same diet supplemented with 6% rumen-protected fats (11% total fat wt/wt; HFD) beginning 2 wk before mating until midgestation (GD75). Maternal HFD increased maternal weight gain, fetal body weight, and low-density lipoprotein levels in the uterine and umbilical circulation but had no significant effects on circulating glucose, triglycerides, or placental fatty acid transporters. Fatty acid (palmitoylcarnitine) oxidation capacity of permeabilized hindlimb muscle fibers was >50% higher in fetuses from HFD pregnancies, whereas pyruvate and maximal (mixed substrate) oxidation capacities were similar to CON. This corresponded to greater triacylglycerol content and protein expression of fatty acid transport and oxidation enzymes in fetal muscle but no significant effect on respiratory chain complexes or pyruvate dehydrogenase expression. However, serine-308 phosphorylation of insulin receptor substrate-1 was greater in fetal muscle from HFD pregnancies along with c-jun-NH2 terminal kinase activation, consistent with prenatal inhibition of skeletal muscle insulin signaling. These results indicate that maternal high-fat feeding shifts fetal skeletal muscle metabolism toward a greater capacity for fatty acid over glucose utilization and favors prenatal development of insulin resistance, which may predispose offspring to metabolic syndrome later in life.NEW & NOTEWORTHY Maternal diet during pregnancy is associated with offspring metabolic risk trajectory in humans and animal models, but the prenatal origins of these effects are less clear. This study examined the effects of a high-fat diet during pregnancy on metabolic risk parameters using a new sheep model. Results align with findings previously reported in nonhuman primates, demonstrating changes in fetal skeletal muscle metabolism that may predispose offspring to metabolic syndrome later in life.
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Affiliation(s)
- Asma K Omar
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Lance C Li Puma
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Luke A Whitcomb
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Briana D Risk
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado, United States
| | - Aria C Witt
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Jason E Bruemmer
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Quinton A Winger
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Gerrit J Bouma
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado, United States
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Jevtovic F, Zheng D, Lopez CA, Kern K, Tanner CJ, Jones TE, Pories WJ, Dohm GL, Houmard JA, May LE, Broskey NT. Greater reliance on glycolysis is associated with lower mitochondrial substrate oxidation and insulin sensitivity in infant myogenic MSCs. Am J Physiol Endocrinol Metab 2023; 325:E207-E213. [PMID: 37467021 PMCID: PMC10511160 DOI: 10.1152/ajpendo.00159.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/27/2023] [Accepted: 07/13/2023] [Indexed: 07/20/2023]
Abstract
Individuals with insulin resistance and obesity display higher skeletal muscle production of nonoxidized glycolytic products (i.e., lactate), and lower complete mitochondrial substrate oxidation to CO2. These findings have also been observed in individuals without obesity and are associated with an increased risk for metabolic disease. The purpose of this study was to determine if substrate preference is evident at the earliest stage of life (birth) and to provide a clinical blood marker (lactate) that could be indicative of a predisposition for metabolic disease later. We used radiolabeled tracers to assess substrate oxidation and insulin sensitivity of myogenically differentiated mesenchymal stem cells (MSCs), a proxy of infant skeletal muscle tissue, derived from umbilical cords of full-term infants. We found that greater production of nonoxidized glycolytic products (lactate, pyruvate, alanine) is directly proportional to lower substrate oxidation and insulin sensitivity in MSCs. In addition, we found an inverse relationship between the ratio of complete glucose oxidation to CO2 and infant blood lactate at 1 mo of age. Collectively, considering that higher lactate was associated with lower MSC glucose oxidation and has been shown to be implicated with metabolic disease, it may be an early indicator of infant skeletal muscle phenotype.NEW & NOTEWORTHY In infant myogenically differentiated mesenchymal stem cells, greater production of nonoxidized glycolytic products was directly proportional to lower substrate oxidation and insulin resistance. Glucose oxidation was inversely correlated with infant blood lactate. This suggests that innate differences in infant substrate oxidation exist at birth and could be associated with the development of metabolic disease later in life. Clinical assessment of infant blood lactate could be used as an early indicator of skeletal muscle phenotype.
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Affiliation(s)
- Filip Jevtovic
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
| | - Donghai Zheng
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
| | - Christian A Lopez
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
| | - Kara Kern
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
| | - Charles J Tanner
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
| | - Terry E Jones
- Department of Physical Therapy, East Carolina University, Greenville, North Carolina, United States
| | - Walter J Pories
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
- Department of Surgery, East Carolina University, Greenville, North Carolina, United States
| | - G Lynis Dohm
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
- Department of Physiology, East Carolina University, Greenville, North Carolina, United States
| | - Joseph A Houmard
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
| | - Linda E May
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
- Department of Obstetrics and Gynecology, East Carolina University, Greenville, North Carolina, United States
| | - Nicholas T Broskey
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, United States
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina, United States
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, United States
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Type 2 Diabetes Related Mitochondrial Defects in Peripheral Mononucleated Blood Cells from Overweight Postmenopausal Women. Biomedicines 2023; 11:biomedicines11010121. [PMID: 36672627 PMCID: PMC9855941 DOI: 10.3390/biomedicines11010121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/24/2022] [Accepted: 12/30/2022] [Indexed: 01/05/2023] Open
Abstract
Type 2 diabetes (T2D) is a multisystem disease that is the subject of many studies, but the earliest cause of the disease has yet to be elucidated. Mitochondrial impairment has been associated with diabetes in several tissues. To extend the association between T2D and mitochondrial impairment to blood cells, we investigated T2D-related changes in peripheral mononucleated blood cells’ (PBMCs) mitochondrial function in two groups of women (CTRL vs. T2D; mean age: 54.1 ± 3.8 vs. 60.9 ± 4.8; mean BMI 25.6 ± 5.2 vs. 30.0 ± 5), together with a panel of blood biomarkers, anthropometric measurements and physiological parameters (VO2max and strength tests). Dual-energy X-ray absorptiometry (DXA) scan analysis, cardio-pulmonary exercise test and blood biomarkers confirmed hallmarks of diabetes in the T2D group. Mitochondrial function assays performed with high resolution respirometry highlighted a significant reduction of mitochondrial respiration in the ADP-stimulated state (OXPHOS; −30%, p = 0.006) and maximal non-coupled respiration (ET; −30%, p = 0.004) in PBMCs samples from the T2D group. The total glutathione antioxidant pool (GSHt) was significantly reduced (−38%: p = 0.04) in plasma samples from the T2D group. The fraction of glycated hemoglobin (Hb1Ac) was positively associated with markers of inflammation (C-reactive protein-CRP r = 0.618; p = 0.006) and of dyslipidemia (triglycerides-TG r = 0.815; p < 0.0001). The same marker (Hb1Ac) was negatively associated with mitochondrial activity levels (OXPHOS r = −0.502; p = 0.034; ET r = −0.529; p = 0.024). The results obtained in overweight postmenopausal women from analysis of PBMCs mitochondrial respiration and their association with anthropometric and physiological parameters indicate that PBMC could represent a reliable model for studying T2D-related metabolic impairment and could be useful for testing the effectiveness of interventions targeting mitochondria.
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Islam H, Gillen JB. Skeletal muscle mechanisms contributing to improved glycemic control following intense interval exercise and training. SPORTS MEDICINE AND HEALTH SCIENCE 2023; 5:20-28. [PMID: 36994179 PMCID: PMC10040385 DOI: 10.1016/j.smhs.2023.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 01/07/2023] [Accepted: 01/11/2023] [Indexed: 01/26/2023] Open
Abstract
High-intensity and sprint interval training (HIIT and SIT, respectively) enhance insulin sensitivity and glycemic control in both healthy adults and those with cardiometabolic diseases. The beneficial effects of intense interval training on glycemic control include both improvements seen in the hours to days following a single session of HIIT/SIT and those which accrue with chronic training. Skeletal muscle is the largest site of insulin-stimulated glucose uptake and plays an integral role in the beneficial effects of exercise on glycemic control. Here we summarize the skeletal muscle responses that contribute to improved glycemic control during and following a single session of interval exercise and evaluate the relationship between skeletal muscle remodelling and improved insulin sensitivity following HIIT/SIT training interventions. Recent evidence suggests that targeting skeletal muscle mechanisms via nutritional interventions around exercise, particularly with carbohydrate manipulation, can enhance the acute glycemic benefits of HIIT. There is also some evidence of sex-based differences in the glycemic benefits of intense interval exercise, with blunted responses observed after training in females relative to males. Differences in skeletal muscle metabolism between males and females may contribute to sex differences in insulin sensitivity following HIIT/SIT, but well-controlled studies evaluating purported muscle mechanisms alongside measurement of insulin sensitivity are needed. Given the greater representation of males in muscle physiology literature, there is also a need for more research involving female-only cohorts to enhance our basic understanding of how intense interval training influences muscle insulin sensitivity in females across the lifespan.
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Handy RM, Holloway GP. Insights into the development of insulin resistance: Unraveling the interaction of physical inactivity, lipid metabolism and mitochondrial biology. Front Physiol 2023; 14:1151389. [PMID: 37153211 PMCID: PMC10157178 DOI: 10.3389/fphys.2023.1151389] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 04/07/2023] [Indexed: 05/09/2023] Open
Abstract
While impairments in peripheral tissue insulin signalling have a well-characterized role in the development of insulin resistance and type 2 diabetes (T2D), the specific mechanisms that contribute to these impairments remain debatable. Nonetheless, a prominent hypothesis implicates the presence of a high-lipid environment, resulting in both reactive lipid accumulation and increased mitochondrial reactive oxygen species (ROS) production in the induction of peripheral tissue insulin resistance. While the etiology of insulin resistance in a high lipid environment is rapid and well documented, physical inactivity promotes insulin resistance in the absence of redox stress/lipid-mediated mechanisms, suggesting alternative mechanisms-of-action. One possible mechanism is a reduction in protein synthesis and the resultant decrease in key metabolic proteins, including canonical insulin signaling and mitochondrial proteins. While reductions in mitochondrial content associated with physical inactivity are not required for the induction of insulin resistance, this could predispose individuals to the detrimental effects of a high-lipid environment. Conversely, exercise-training induced mitochondrial biogenesis has been implicated in the protective effects of exercise. Given mitochondrial biology may represent a point of convergence linking impaired insulin sensitivity in both scenarios of chronic overfeeding and physical inactivity, this review aims to describe the interaction between mitochondrial biology, physical (in)activity and lipid metabolism within the context of insulin signalling.
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Nieblas B, Pérez-Treviño P, García N. Role of mitochondria-associated endoplasmic reticulum membranes in insulin sensitivity, energy metabolism, and contraction of skeletal muscle. Front Mol Biosci 2022; 9:959844. [PMID: 36275635 PMCID: PMC9585326 DOI: 10.3389/fmolb.2022.959844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 08/04/2022] [Indexed: 11/29/2022] Open
Abstract
Skeletal muscle has a critical role in the regulation of the energy balance of the organism, particularly as the principal tissue responsible for insulin-stimulated glucose disposal and as the major site of peripheral insulin resistance (IR), which has been related to accumulation of lipid intermediates, reduced oxidative capacity of mitochondria and endoplasmic reticulum (ER) stress. These organelles form contact sites, known as mitochondria-associated ER membranes (MAMs). This interconnection seems to be involved in various cellular processes, including Ca2+ transport and energy metabolism; therefore, MAMs could play an important role in maintaining cellular homeostasis. Evidence suggests that alterations in MAMs may contribute to IR. However, the evidence does not refer to a specific subcellular location, which is of interest due to the fact that skeletal muscle is constituted by oxidative and glycolytic fibers as well as different mitochondrial populations that appear to respond differently to stimuli and pathological conditions. In this review, we show the available evidence of possible differential responses in the formation of MAMs in skeletal muscle as well as its role in insulin signaling and the beneficial effect it could have in the regulation of energetic metabolism and muscular contraction.
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Affiliation(s)
- Bianca Nieblas
- Escuela de Medicina y Ciencias de la Salud, Tecnologico de Monterrey, Monterrey, Nuevo León, México
- Experimental Medicine and Advanced Therapies, The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Nuevo León, México
| | - Perla Pérez-Treviño
- Experimental Medicine and Advanced Therapies, The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Nuevo León, México
| | - Noemí García
- Escuela de Medicina y Ciencias de la Salud, Tecnologico de Monterrey, Monterrey, Nuevo León, México
- Experimental Medicine and Advanced Therapies, The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Nuevo León, México
- *Correspondence: Noemí García,
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Blackwood SJ, Horwath O, Moberg M, Pontén M, Apró W, Ekblom MM, Larsen FJ, Katz A. Extreme Variations in Muscle Fiber Composition Enable Detection of Insulin Resistance and Excessive Insulin Secretion. J Clin Endocrinol Metab 2022; 107:e2729-e2737. [PMID: 35405014 DOI: 10.1210/clinem/dgac221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Indexed: 12/16/2022]
Abstract
CONTEXT Muscle fiber composition is associated with peripheral insulin action. OBJECTIVE We investigated whether extreme differences in muscle fiber composition are associated with alterations in peripheral insulin action and secretion in young, healthy subjects who exhibit normal fasting glycemia and insulinemia. METHODS Relaxation time following a tetanic contraction was used to identify subjects with a high or low expression of type I muscle fibers: group 1 (n = 11), area occupied by type I muscle fibers = 61.0 ± 11.8%, and group 2 (n = 8), type I area = 36.0 ± 4.9% (P < 0.001). Biopsies were obtained from the vastus lateralis muscle and analyzed for mitochondrial respiration on permeabilized fibers, muscle fiber composition, and capillary density. An intravenous glucose tolerance test was performed and indices of glucose tolerance, insulin sensitivity, and secretion were determined. RESULTS Glucose tolerance was similar between groups, whereas whole-body insulin sensitivity was decreased by ~50% in group 2 vs group 1 (P = 0.019). First-phase insulin release (area under the insulin curve during 10 minutes after glucose infusion) was increased by almost 4-fold in group 2 vs group 1 (P = 0.01). Whole-body insulin sensitivity was correlated with percentage area occupied by type I fibers (r = 0.54; P = 0.018) and capillary density in muscle (r = 0.61; P = 0.005) but not with mitochondrial respiration. Insulin release was strongly related to percentage area occupied by type II fibers (r = 0.93; P < 0.001). CONCLUSIONS Assessment of muscle contractile function in young healthy subjects may prove useful in identifying individuals with insulin resistance and enhanced glucose-stimulated insulin secretion prior to onset of clinical manifestations.
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Affiliation(s)
- Sarah J Blackwood
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Oscar Horwath
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Marcus Moberg
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Marjan Pontén
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - William Apró
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Maria M Ekblom
- Department of Physical Activity and Health, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Filip J Larsen
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Abram Katz
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
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11
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Xia H, Scholtes C, Dufour CR, Ouellet C, Ghahremani M, Giguère V. Insulin action and resistance are dependent on a GSK3β-FBXW7-ERRα transcriptional axis. Nat Commun 2022; 13:2105. [PMID: 35440636 PMCID: PMC9019090 DOI: 10.1038/s41467-022-29722-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 03/30/2022] [Indexed: 12/15/2022] Open
Abstract
Insulin resistance, a harbinger of the metabolic syndrome, is a state of compromised hormonal response resulting from the dysregulation of a wide range of insulin-controlled cellular processes. However, how insulin affects cellular energy metabolism via long-term transcriptional regulation and whether boosting mitochondrial function alleviates insulin resistance remains to be elucidated. Herein we reveal that insulin directly enhances the activity of the nuclear receptor ERRα via a GSK3β/FBXW7 signaling axis. Liver-specific deletion of GSK3β or FBXW7 and mice harboring mutations of ERRα phosphosites (ERRα3SA) co-targeted by GSK3β/FBXW7 result in accumulated ERRα proteins that no longer respond to fluctuating insulin levels. ERRα3SA mice display reprogrammed liver and muscle transcriptomes, resulting in compromised energy homeostasis and reduced insulin sensitivity despite improved mitochondrial function. This crossroad of insulin signaling and transcriptional control by a nuclear receptor offers a framework to better understand the complex cellular processes contributing to the development of insulin resistance.
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Affiliation(s)
- Hui Xia
- Rosalind and Morris Goodman Cancer Research Institute, McGill University, Montréal, QC, H3A 1A3, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Charlotte Scholtes
- Rosalind and Morris Goodman Cancer Research Institute, McGill University, Montréal, QC, H3A 1A3, Canada
| | - Catherine R Dufour
- Rosalind and Morris Goodman Cancer Research Institute, McGill University, Montréal, QC, H3A 1A3, Canada
| | - Carlo Ouellet
- Rosalind and Morris Goodman Cancer Research Institute, McGill University, Montréal, QC, H3A 1A3, Canada
| | - Majid Ghahremani
- Rosalind and Morris Goodman Cancer Research Institute, McGill University, Montréal, QC, H3A 1A3, Canada
| | - Vincent Giguère
- Rosalind and Morris Goodman Cancer Research Institute, McGill University, Montréal, QC, H3A 1A3, Canada.
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montréal, QC, H3G 1Y6, Canada.
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12
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Marzoog B. Lipid Behavior in Metabolic Syndrome Pathophysiology. Curr Diabetes Rev 2022; 18:e150921196497. [PMID: 34525924 DOI: 10.2174/1573399817666210915101321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 06/17/2021] [Accepted: 07/16/2021] [Indexed: 02/08/2023]
Abstract
Undeniably, lipid plays an extremely important role in the homeostasis balance since lipid contributes to the regulation of the metabolic processes. The metabolic syndrome pathogenesis is multi-pathway that composes neurohormonal disorders, endothelial cell dysfunction, metabolic disturbance, genetic predisposition, in addition to gut commensal microbiota. The heterogenicity of the possible mechanisms gives the metabolic syndrome its complexity and limitation of therapeutic accesses. The main pathological link is that lipid contributes to the emergence of metabolic syndrome via central obesity and visceral obesity that consequently lead to oxidative stress and chronic inflammatory response promotion. Physiologically, a balance is kept between the adiponectin and adipokines levels to maintain the lipid level in the organism. Clinically, extremely important to define the borders of the lipid level in which the pathogenesis of the metabolic syndrome is reversible, otherwise it will be accompanied by irreversible complications and sequelae of the metabolic syndrome (cardiovascular, insulin resistance). The present paper is dedicated to providing novel insights into the role of lipid in the development of metabolic syndrome; hence dyslipidemia is the initiator of insulin resistance syndrome (metabolic syndrome).
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Affiliation(s)
- Basheer Marzoog
- Department of Medical School Student, National Research Mordovia State University, Russian Federation
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13
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Wang D, Jiang DM, Yu RR, Zhang LL, Liu YZ, Chen JX, Chen HC, Liu YP. The Effect of Aerobic Exercise on the Oxidative Capacity of Skeletal Muscle Mitochondria in Mice with Impaired Glucose Tolerance. J Diabetes Res 2022; 2022:3780156. [PMID: 35712028 PMCID: PMC9197611 DOI: 10.1155/2022/3780156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 05/05/2022] [Accepted: 05/23/2022] [Indexed: 12/03/2022] Open
Abstract
METHODS Male C57BL/6J mice were randomly divided into six different experimental groups (8 animals/group): (1) normal group (NOR), (2) normal control group (NC), (3) normal + exercise group (NE), (4) IGT group (IGT), (5) IGT control group (IC), and (6) IGT+ exercise group (IE).The exercise group received aerobic exercise for 8 weeks. After the intervention, a blood glucose meter was used to detect the level of glucose tolerance in the mouse's abdominal cavity; a biochemical kit was used to detect serum lipid metabolism indicators, malondialdehyde, and superoxide dismutase levels; the ELISA method was used to detect serum insulin and mouse gastrocnemius homogenate LDH, PDH, SDH, and CCO levels. Western blot method was used to detect the protein expression levels of NOX4, PGC-1α, and Mfn2 in the gastrocnemius muscle of mice. RESULTS (1) Mice with high-fat diet for 30 weeks showed impaired glucose tolerance, insulin resistance, and lipid metabolism disorders. The level of LDH, PDH, SDH, and CCO in the gastrocnemius homogenate of mice was reduced. The expressions of NOX4 protein were significantly upregulated, while the expressions of PGC-1α and Mfn2 proteins were significantly downregulated. (2) 8-week aerobic exercise improved the disorders of glucose and lipid metabolism in IGT mice and increased homogenized LDH, PDH, SDH, and CCO levels, and the expressions of NOX4, PGC-1α, and Mfn2 proteins in the gastrocnemius muscle of mice were reversed. It is speculated that aerobic exercise can accelerate energy metabolism. CONCLUSION (1) C57BL/6 mice were fed high fat for 30 weeks and successfully constructed a mouse model of reduced diabetes; the mice with reduced diabetes have impaired glucose tolerance, insulin resistance, and lipid metabolism disorders; (2) 8 weeks of aerobic exercise improve glucose tolerance, reduce glucose tolerance in mice, reduce insulin resistance, improve lipid metabolism disorders, and reduce oxidative stress; (3) 8-week aerobic exercise reduces skeletal muscle NOX4 expression and increases glucose tolerance; reduces the expression of LDH, PDH, SDH, and CCO in mouse skeletal muscle; increases the expression level of mitochondrial fusion protein 2 and PGC-1α; improves glucose tolerance; reduces energy metabolism of mouse skeletal muscle; reduces oxidative stress; and reduces insulin resistance. It is speculated that aerobic exercise can accelerate energy metabolism. This process may involve two aspects: firstly, increase the expression level of oxidative metabolism enzymes and promote the tricarboxylic acid cycle; secondly, increase the expression of Mfn2 and accelerate mitochondria fission or fusion to regulate energy metabolism, thereby reducing oxidative stress and insulin resistance.
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Affiliation(s)
- Dan Wang
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Dong-Mou Jiang
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Rong-Rong Yu
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Lin-Lin Zhang
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Yan-Zhong Liu
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Jia-Xin Chen
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Hai-Chun Chen
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
| | - Yi-Ping Liu
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, China
- Key Laboratory of Kinesiological Evaluation General Administration of Sport of China, Fujian Province, China
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14
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Energy transfer between the mitochondrial network and lipid droplets in insulin resistant skeletal muscle. CURRENT OPINION IN PHYSIOLOGY 2021; 24:100487. [PMID: 35274067 PMCID: PMC8903156 DOI: 10.1016/j.cophys.2022.100487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondria and lipid droplets in the insulin resistant skeletal muscle of type 2 diabetic individuals have both been heavily investigated independently and are characterized by more fragmented, dysfunctional mitochondrial networks and larger lipid droplets compared to skeletal muscle of healthy individuals. Specialized contacts between mitochondrial and lipid droplet membranes are known to decrease in diabetic muscle, though it remains unclear how energy transfer at the remaining mitochondria-lipid droplet contact sites may be altered by type 2 diabetes. The purpose of this review is to highlight recent data on mitochondrial structure and function and lipid droplet dynamics in type 2 diabetic skeletal muscle and to underscore the need for more detailed investigations into the functional nature of mitochondria-lipid droplet interactions in type 2 diabetes.
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15
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Revisiting the contribution of mitochondrial biology to the pathophysiology of skeletal muscle insulin resistance. Biochem J 2021; 478:3809-3826. [PMID: 34751699 DOI: 10.1042/bcj20210145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 12/18/2022]
Abstract
While the etiology of type 2 diabetes is multifaceted, the induction of insulin resistance in skeletal muscle is a key phenomenon, and impairments in insulin signaling in this tissue directly contribute to hyperglycemia. Despite the lack of clarity regarding the specific mechanisms whereby insulin signaling is impaired, the key role of a high lipid environment within skeletal muscle has been recognized for decades. Many of the proposed mechanisms leading to the attenuation of insulin signaling - namely the accumulation of reactive lipids and the pathological production of reactive oxygen species (ROS), appear to rely on this high lipid environment. Mitochondrial biology is a central component to these processes, as these organelles are almost exclusively responsible for the oxidation and metabolism of lipids within skeletal muscle and are a primary source of ROS production. Classic studies have suggested that reductions in skeletal muscle mitochondrial content and/or function contribute to lipid-induced insulin resistance; however, in recent years the role of mitochondria in the pathophysiology of insulin resistance has been gradually re-evaluated to consider the biological effects of alterations in mitochondrial content. In this respect, while reductions in mitochondrial content are not required for the induction of insulin resistance, mechanisms that increase mitochondrial content are thought to enhance mitochondrial substrate sensitivity and submaximal adenosine diphosphate (ADP) kinetics. Thus, this review will describe the central role of a high lipid environment in the pathophysiology of insulin resistance, and present both classic and contemporary views of how mitochondrial biology contributes to insulin resistance in skeletal muscle.
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16
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Schmidt CA, Fisher-Wellman KH, Neufer PD. From OCR and ECAR to energy: Perspectives on the design and interpretation of bioenergetics studies. J Biol Chem 2021; 297:101140. [PMID: 34461088 PMCID: PMC8479256 DOI: 10.1016/j.jbc.2021.101140] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 12/12/2022] Open
Abstract
Biological energy transduction underlies all physiological phenomena in cells. The metabolic systems that support energy transduction have been of great interest due to their association with numerous pathologies including diabetes, cancer, rare genetic diseases, and aberrant cell death. Commercially available bioenergetics technologies (e.g., extracellular flux analysis, high-resolution respirometry, fluorescent dye kits, etc.) have made practical assessment of metabolic parameters widely accessible. This has facilitated an explosion in the number of studies exploring, in particular, the biological implications of oxygen consumption rate (OCR) and substrate level phosphorylation via glycolysis (i.e., via extracellular acidification rate (ECAR)). Though these technologies have demonstrated substantial utility and broad applicability to cell biology research, they are also susceptible to historical assumptions, experimental limitations, and other caveats that have led to premature and/or erroneous interpretations. This review enumerates various important considerations for designing and interpreting cellular and mitochondrial bioenergetics experiments, some common challenges and pitfalls in data interpretation, and some potential "next steps" to be taken that can address these highlighted challenges.
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Affiliation(s)
- Cameron A Schmidt
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Departments of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Departments of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Departments of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA; Departments of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
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17
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Flensted-Jensen M, Gram M, Dela F, Helge JW, Larsen S. Six weeks of high intensity cycle training reduces H 2O 2 emission and increases antioxidant protein levels in obese adults with risk factors for type 2 diabetes. Free Radic Biol Med 2021; 173:1-6. [PMID: 34273538 DOI: 10.1016/j.freeradbiomed.2021.07.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/07/2021] [Accepted: 07/14/2021] [Indexed: 11/16/2022]
Abstract
Obesity has been associated with increased production of reactive oxygen species (ROS), which may be involved in the development of cardiovascular disease and type 2 diabetes (T2D). Endurance exercise lowers ROS production and increases antioxidant capacity in muscle cells, but it is currently unknown whether high intensity interval training (HIT) elicits the same effects. Twelve sedentary obese subjects at risk of developing T2D took part in a six-week intervention, performing three HIT sessions per week (five 1-min sets of high-intensity cycling (125% of VO2peak), with 90 s recovery in between sets). Muscle biopsies were obtained for assessment of ROS production (H2O2 emission), mitochondrial respiratory capacity, and antioxidant protein levels before and after the intervention. H2O2 emission decreased 60.4% after the intervention (Succinate 3 mmol・l-1), concurrent with a 35.1% increase in protein levels of the antioxidant manganese superoxide dismutase (MnSOD) and a trend towards increased levels of the antioxidant catalase (p = 0.06, 72.9%). These findings were accompanied by a 19% increased mitochondrial respiratory capacity (CI + II), a 6.9% increased VO2peak and a 1.7% lower body fat percentage. These effects were achieved after just 15 min of high-intensity work and 40 min of total time spent per week. Overall, this suggests that a relatively small amount of HIT is sufficient to induce beneficial effects on ROS production and antioxidant status in muscle cells, which may lower oxidative stress and potentially protect against the development of cardiovascular disease.
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Affiliation(s)
- Mathias Flensted-Jensen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark.
| | - Martin Gram
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark.
| | - Flemming Dela
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark; Department of Geriatrics, Bispebjerg University Hospital, Copenhagen, Denmark.
| | - Jørn Wulff Helge
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark.
| | - Steen Larsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark; Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland.
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18
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Langlois A, Forterre A, Pinget M, Bouzakri K. Impact of moderate exercise on fatty acid oxidation in pancreatic β-cells and skeletal muscle. J Endocrinol Invest 2021; 44:1815-1825. [PMID: 33844166 PMCID: PMC8357749 DOI: 10.1007/s40618-021-01551-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/03/2021] [Indexed: 12/13/2022]
Abstract
Fatty acids (FA) play a crucial role in glycaemia regulation in healthy and metabolic disorders conditions through various mechanisms. FA oxidation is one of the processes involved in lipid metabolism and can be modulated by exercise. Nowadays, physical activity is known to be an effective strategy for the prevention and treatment of Type 2 Diabetes. Moreover, its intensity, its duration, the sex-gender, the prandial state, exerkines… are as many parameters that can influence glycaemic control. However, the widely debated question is to determine the best type of exercise for patients with metabolic disorders. In this review, we will discuss the impact of exercise intensity, especially moderate activity, on glycaemic control by focussing on FA oxidation in pancreatic β-cells and skeletal muscle. Finally, thanks to all the recent data, we will determine whether moderate physical activity is a good therapeutic strategy and if FA oxidation represents a target of interest to treat diabetic, obese and insulin-resistant patients.
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Affiliation(s)
- A Langlois
- Centre Européen D'étude du Diabète, Unité Mixte de Recherche de L'Université de Strasbourg « Diabète et Thérapeutique », Strasbourg, France
| | - A Forterre
- Centre Européen D'étude du Diabète, Unité Mixte de Recherche de L'Université de Strasbourg « Diabète et Thérapeutique », Strasbourg, France
| | - M Pinget
- Centre Européen D'étude du Diabète, Unité Mixte de Recherche de L'Université de Strasbourg « Diabète et Thérapeutique », Strasbourg, France
| | - K Bouzakri
- Centre Européen D'étude du Diabète, Unité Mixte de Recherche de L'Université de Strasbourg « Diabète et Thérapeutique », Strasbourg, France.
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Reed J, Bain S, Kanamarlapudi V. A Review of Current Trends with Type 2 Diabetes Epidemiology, Aetiology, Pathogenesis, Treatments and Future Perspectives. Diabetes Metab Syndr Obes 2021; 14:3567-3602. [PMID: 34413662 PMCID: PMC8369920 DOI: 10.2147/dmso.s319895] [Citation(s) in RCA: 122] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/09/2021] [Indexed: 12/13/2022] Open
Abstract
Type 2 diabetes (T2D), which has currently become a global pandemic, is a metabolic disease largely characterised by impaired insulin secretion and action. Significant progress has been made in understanding T2D aetiology and pathogenesis, which is discussed in this review. Extrapancreatic pathology is also summarised, which demonstrates the highly multifactorial nature of T2D. Glucagon-like peptide (GLP)-1 is an incretin hormone responsible for augmenting insulin secretion from pancreatic beta-cells during the postprandial period. Given that native GLP-1 has a very short half-life, GLP-1 mimetics with a much longer half-life have been developed, which are currently an effective treatment option for T2D by enhancing insulin secretion in patients. Interestingly, there is continual emerging evidence that these therapies alleviate some of the post-diagnosis complications of T2D. Additionally, these therapies have been shown to induce weight loss in patients, suggesting they could be an alternative to bariatric surgery, a procedure associated with numerous complications. Current GLP-1-based therapies all act as orthosteric agonists for the GLP-1 receptor (GLP-1R). Interestingly, it has emerged that GLP-1R also has allosteric binding sites and agonists have been developed for these sites to test their therapeutic potential. Recent studies have also demonstrated the potential of bi- and tri-agonists, which target multiple hormonal receptors including GLP-1R, to more effectively treat T2D. Improved understanding of T2D aetiology/pathogenesis, coupled with the further elucidation of both GLP-1 activity/targets and GLP-1R mechanisms of activation via different agonists, will likely provide better insight into the therapeutic potential of GLP-1-based therapies to treat T2D.
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Affiliation(s)
- Josh Reed
- Institute of Life Science 1, Medical School, Swansea University, Swansea, SA2 8PP, UK
| | - Stephen Bain
- Institute of Life Science 1, Medical School, Swansea University, Swansea, SA2 8PP, UK
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20
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Kunz HE, Hart CR, Gries KJ, Parvizi M, Laurenti M, Dalla Man C, Moore N, Zhang X, Ryan Z, Polley EC, Jensen MD, Vella A, Lanza IR. Adipose tissue macrophage populations and inflammation are associated with systemic inflammation and insulin resistance in obesity. Am J Physiol Endocrinol Metab 2021; 321:E105-E121. [PMID: 33998291 PMCID: PMC8321823 DOI: 10.1152/ajpendo.00070.2021] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Obesity is accompanied by numerous systemic and tissue-specific derangements, including systemic inflammation, insulin resistance, and mitochondrial abnormalities in skeletal muscle. Despite growing recognition that adipose tissue dysfunction plays a role in obesity-related disorders, the relationship between adipose tissue inflammation and other pathological features of obesity is not well-understood. We assessed macrophage populations and measured the expression of inflammatory cytokines in abdominal adipose tissue biopsies in 39 nondiabetic adults across a range of body mass indexes (BMI 20.5-45.8 kg/m2). Skeletal muscle biopsies were used to evaluate mitochondrial respiratory capacity, ATP production capacity, coupling, and reactive oxygen species production. Insulin sensitivity (SI) and β cell responsivity were determined from test meal postprandial glucose, insulin, c-peptide, and triglyceride kinetics. We examined the relationships between adipose tissue inflammatory markers, systemic inflammatory markers, SI, and skeletal muscle mitochondrial physiology. BMI was associated with increased adipose tissue and systemic inflammation, reduced SI, and reduced skeletal muscle mitochondrial oxidative capacity. Adipose-resident macrophage numbers were positively associated with circulating inflammatory markers, including tumor necrosis factor-α (TNFα) and C-reactive protein (CRP). Local adipose tissue inflammation and circulating concentrations of TNFα and CRP were negatively associated with SI, and circulating concentrations of TNFα and CRP were also negatively associated with skeletal muscle oxidative capacity. These results demonstrate that obese humans exhibit increased adipose tissue inflammation concurrently with increased systemic inflammation, reduced insulin sensitivity, and reduced muscle oxidative capacity and suggest that adipose tissue and systemic inflammation may drive obesity-associated metabolic derangements.NEW AND NOTEWORTHY Adipose inflammation is proposed to be at the nexus of the systemic inflammation and metabolic derangements associated with obesity. The present study provides evidence to support adipose inflammation as a central feature of the pathophysiology of obesity. Adipose inflammation is associated with systemic and peripheral metabolic derangements, including increased systemic inflammation, reduced insulin sensitivity, and reduced skeletal muscle mitochondrial respiration.
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Affiliation(s)
- Hawley E Kunz
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Corey R Hart
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Kevin J Gries
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Mojtaba Parvizi
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Marcello Laurenti
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Chiara Dalla Man
- Biomedical Engineering and Physiology Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota
| | - Natalie Moore
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Xiaoyan Zhang
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Zachary Ryan
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Eric C Polley
- Division of Biomedical Statistics and Informatics, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Michael D Jensen
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Adrian Vella
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Ian R Lanza
- Endocrine Research Unit, Division of Endocrinology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
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21
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Öhman T, Teppo J, Datta N, Mäkinen S, Varjosalo M, Koistinen HA. Skeletal muscle proteomes reveal downregulation of mitochondrial proteins in transition from prediabetes into type 2 diabetes. iScience 2021; 24:102712. [PMID: 34235411 PMCID: PMC8246593 DOI: 10.1016/j.isci.2021.102712] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/17/2021] [Accepted: 06/08/2021] [Indexed: 12/22/2022] Open
Abstract
Skeletal muscle insulin resistance is a central defect in the pathogenesis of type 2 diabetes (T2D). Here, we analyzed skeletal muscle proteome in 148 vastus lateralis muscle biopsies obtained from men covering all glucose tolerance phenotypes: normal, impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and T2D. Skeletal muscle proteome was analyzed by a sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics technique. Our data indicate a downregulation in several proteins involved in mitochondrial electron transport or respiratory chain complex assembly already in IFG and IGT muscles, with most profound decreases observed in T2D. Additional phosphoproteomic analysis reveals altered phosphorylation in several signaling pathways in IFG, IGT, and T2D muscles, including those regulating glucose metabolic processes, and the structure of muscle cells. These data reveal several alterations present in skeletal muscle already in prediabetes and highlight impaired mitochondrial energy metabolism in the trajectory from prediabetes into T2D. Skeletal muscle proteome from men with all stages of glucose tolerance was analyzed Phosphoproteomics reveal altered phosphorylation in IFG, IGT, and T2D muscles OXPHOS proteins are decreased in prediabetic muscles, with most decrease in T2D
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Affiliation(s)
- Tiina Öhman
- University of Helsinki, Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, 00014 Helsinki, Finland
| | - Jaakko Teppo
- University of Helsinki, Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, 00014 Helsinki, Finland.,University of Helsinki, Drug Research Program, Faculty of Pharmacy, 00014 Helsinki, Finland
| | - Neeta Datta
- University of Helsinki, Department of Medicine, Helsinki University Hospital, Haartmaninkatu 4, PO BOX 340, 00029 HUS, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Selina Mäkinen
- University of Helsinki, Department of Medicine, Helsinki University Hospital, Haartmaninkatu 4, PO BOX 340, 00029 HUS, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Markku Varjosalo
- University of Helsinki, Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, 00014 Helsinki, Finland
| | - Heikki A Koistinen
- University of Helsinki, Department of Medicine, Helsinki University Hospital, Haartmaninkatu 4, PO BOX 340, 00029 HUS, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
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22
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Flockhart M, Nilsson LC, Tais S, Ekblom B, Apró W, Larsen FJ. Excessive exercise training causes mitochondrial functional impairment and decreases glucose tolerance in healthy volunteers. Cell Metab 2021; 33:957-970.e6. [PMID: 33740420 DOI: 10.1016/j.cmet.2021.02.017] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 11/18/2020] [Accepted: 02/22/2021] [Indexed: 12/19/2022]
Abstract
Exercise training positively affects metabolic health through increased mitochondrial oxidative capacity and improved glucose regulation and is the first line of treatment in several metabolic diseases. However, the upper limit of the amount of exercise associated with beneficial therapeutic effects has not been clearly identified. Here, we used a training model with a progressively increasing exercise load during an intervention over 4 weeks. We closely followed changes in glucose tolerance, mitochondrial function and dynamics, physical exercise capacity, and whole-body metabolism. Following the week with the highest exercise load, we found a striking reduction in intrinsic mitochondrial function that coincided with a disturbance in glucose tolerance and insulin secretion. We also assessed continuous blood glucose profiles in world-class endurance athletes and found that they had impaired glucose control compared with a matched control group.
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Affiliation(s)
- Mikael Flockhart
- The Swedish School of Sport and Health Sciences, GIH, Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, Stockholm 114 33, Sweden.
| | - Lina C Nilsson
- The Swedish School of Sport and Health Sciences, GIH, Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, Stockholm 114 33, Sweden
| | - Senna Tais
- The Swedish School of Sport and Health Sciences, GIH, Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, Stockholm 114 33, Sweden
| | - Björn Ekblom
- The Swedish School of Sport and Health Sciences, GIH, Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, Stockholm 114 33, Sweden
| | - William Apró
- The Swedish School of Sport and Health Sciences, GIH, Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, Stockholm 114 33, Sweden; Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Filip J Larsen
- The Swedish School of Sport and Health Sciences, GIH, Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, Stockholm 114 33, Sweden.
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23
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Houzelle A, Jörgensen JA, Schaart G, Daemen S, van Polanen N, Fealy CE, Hesselink MKC, Schrauwen P, Hoeks J. Human skeletal muscle mitochondrial dynamics in relation to oxidative capacity and insulin sensitivity. Diabetologia 2021; 64:424-436. [PMID: 33258025 PMCID: PMC7801361 DOI: 10.1007/s00125-020-05335-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 10/02/2020] [Indexed: 12/19/2022]
Abstract
AIMS/HYPOTHESIS Mitochondria operate in networks, adapting to external stresses and changes in cellular metabolic demand and are subject to various quality control mechanisms. On the basis of these traits, we here hypothesise that the regulation of mitochondrial networks in skeletal muscle is hampered in humans with compromised oxidative capacity and insulin sensitivity. METHODS In a cross-sectional design, we compared four groups of participants (selected from previous studies) ranging in aerobic capacity and insulin sensitivity, i.e. participants with type 2 diabetes (n = 11), obese participants without diabetes (n = 12), lean individuals (n = 10) and endurance-trained athletes (n = 12); basal, overnight fasted muscle biopsies were newly analysed for the current study and we compared the levels of essential mitochondrial dynamics and quality control regulatory proteins in skeletal muscle tissue. RESULTS Type 2 diabetes patients and obese participants were older than lean participants and athletes (58.6 ± 4.0 and 56.7 ± 7.2 vs 21.8 ± 2.5 and 25.1 ± 4.3 years, p < 0.001, respectively) and displayed a higher BMI (32.4 ± 3.7 and 31.0 ± 3.7 vs 22.1 ± 1.8 and 21.0 ± 1.5 kg/m2, p < 0.001, respectively) than lean individuals and endurance-trained athletes. Fission protein 1 (FIS1) and optic atrophy protein 1 (OPA1) protein content was highest in muscle from athletes and lowest in participants with type 2 diabetes and obesity, respectively (FIS1: 1.86 ± 0.79 vs 0.79 ± 0.51 AU, p = 0.002; and OPA1: 1.55 ± 0.64 vs 0.76 ± 0.52 AU, p = 0.014), which coincided with mitochondrial network fragmentation in individuals with type 2 diabetes, as assessed by confocal microscopy in a subset of type 2 diabetes patients vs endurance-trained athletes (n = 6). Furthermore, lean individuals and athletes displayed a mitonuclear protein balance that was different from obese participants and those with type 2 diabetes. Mitonuclear protein balance also associated with heat shock protein 60 (HSP60) protein levels, which were higher in athletes when compared with participants with obesity (p = 0.048) and type 2 diabetes (p = 0.002), indicative for activation of the mitochondrial unfolded protein response. Finally, OPA1, FIS1 and HSP60 correlated positively with aerobic capacity (r = 0.48, p = 0.0001; r = 0.55, p < 0.001 and r = 0.61, p < 0.0001, respectively) and insulin sensitivity (r = 0.40, p = 0.008; r = 0.44, p = 0.003 and r = 0.48, p = 0.001, respectively). CONCLUSIONS/INTERPRETATION Collectively, our data suggest that mitochondrial dynamics and quality control in skeletal muscle are linked to oxidative capacity in humans, which may play a role in the maintenance of muscle insulin sensitivity. CLINICAL TRIAL REGISTRY: numbers NCT00943059, NCT01298375 and NL1888 Graphical abstract.
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Affiliation(s)
- Alexandre Houzelle
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Johanna A Jörgensen
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Gert Schaart
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Sabine Daemen
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Nynke van Polanen
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Ciarán E Fealy
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Matthijs K C Hesselink
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Joris Hoeks
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
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24
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Abstract
The current paradigm of type 2 diabetes (T2D) is gluco-centric, being exclusively categorized by glycemic characteristics. The gluco-centric paradigm views hyperglycemia as the primary target, being driven by resistance to insulin combined with progressive beta cells failure, and considers glycemic control its ultimate treatment goal. Most importantly, the gluco-centric paradigm considers the non-glycemic diseases associated with T2D, e.g., obesity, dyslipidemia, hypertension, macrovascular disease, microvascular disease and fatty liver as 'risk factors' and/or 'outcomes' and/or 'comorbidities', rather than primary inherent disease aspects of T2D. That is in spite of their high prevalence (60-90%) and major role in profiling T2D morbidity and mortality. Moreover, the gluco-centric paradigm fails to realize that the non-glycemic diseases of T2D are driven by insulin and, except for glycemic control, response to insulin in T2D is essentially the rule rather than the exception. Failure of the gluco-centric paradigm to offer an exhaustive unifying view of the glycemic and non-glycemic diseases of T2D may have contributed to T2D being still an unmet need. An mTORC1-centric paradigm maintains that hyperactive mTORC1 drives the glycemic and non-glycemic disease aspects of T2D. Hyperactive mTORC1 is proposed to act as double-edged agent, namely, to interfere with glycemic control by disrupting the insulin receptor-Akt transduction pathway, while concomitantly driving the non-glycemic diseases of T2D. The mTORC1-centric paradigm may offer a novel perspective for T2D in terms of pathogenesis, clinical focus and treatment strategy.
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Affiliation(s)
- Jacob Bar-Tana
- Hebrew University Medical School, 91120, Jerusalem, Israel.
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25
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Genders AJ, Holloway GP, Bishop DJ. Are Alterations in Skeletal Muscle Mitochondria a Cause or Consequence of Insulin Resistance? Int J Mol Sci 2020; 21:ijms21186948. [PMID: 32971810 PMCID: PMC7554894 DOI: 10.3390/ijms21186948] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 12/14/2022] Open
Abstract
As a major site of glucose uptake following a meal, skeletal muscle has an important role in whole-body glucose metabolism. Evidence in humans and animal models of insulin resistance and type 2 diabetes suggests that alterations in mitochondrial characteristics accompany the development of skeletal muscle insulin resistance. However, it is unclear whether changes in mitochondrial content, respiratory function, or substrate oxidation are central to the development of insulin resistance or occur in response to insulin resistance. Thus, this review will aim to evaluate the apparent conflicting information placing mitochondria as a key organelle in the development of insulin resistance in skeletal muscle.
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Affiliation(s)
- Amanda J. Genders
- Institute for Health and Sport (iHeS), Victoria University, Melbourne 8001, Australia;
- Correspondence: ; Tel.: +61-3-9919-9556
| | - Graham P. Holloway
- Dept. Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada;
| | - David J. Bishop
- Institute for Health and Sport (iHeS), Victoria University, Melbourne 8001, Australia;
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26
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p38 MAPK in Glucose Metabolism of Skeletal Muscle: Beneficial or Harmful? Int J Mol Sci 2020; 21:ijms21186480. [PMID: 32899870 PMCID: PMC7555282 DOI: 10.3390/ijms21186480] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 12/24/2022] Open
Abstract
Skeletal muscles respond to environmental and physiological changes by varying their size, fiber type, and metabolic properties. P38 mitogen-activated protein kinase (MAPK) is one of several signaling pathways that drive the metabolic adaptation of skeletal muscle to exercise. p38 MAPK also participates in the development of pathological traits resulting from excessive caloric intake and obesity that cause metabolic syndrome and type 2 diabetes (T2D). Whereas p38 MAPK increases insulin-independent glucose uptake and oxidative metabolism in muscles during exercise, it contrastingly mediates insulin resistance and glucose intolerance during metabolic syndrome development. This article provides an overview of the apparent contradicting roles of p38 MAPK in the adaptation of skeletal muscles to exercise and to pathological conditions leading to glucose intolerance and T2D. Here, we focus on the involvement of p38 MAPK in glucose metabolism of skeletal muscle, and discuss the possibility of targeting this pathway to prevent the development of T2D.
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27
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Ryan BJ, Schleh MW, Ahn C, Ludzki AC, Gillen JB, Varshney P, Van Pelt DW, Pitchford LM, Chenevert TL, Gioscia-Ryan RA, Howton SM, Rode T, Hummel SL, Burant CF, Little JP, Horowitz JF. Moderate-Intensity Exercise and High-Intensity Interval Training Affect Insulin Sensitivity Similarly in Obese Adults. J Clin Endocrinol Metab 2020; 105:5850995. [PMID: 32492705 PMCID: PMC7347288 DOI: 10.1210/clinem/dgaa345] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 05/28/2020] [Indexed: 01/25/2023]
Abstract
OBJECTIVE We compared the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on insulin sensitivity and other important metabolic adaptations in adults with obesity. METHODS Thirty-one inactive adults with obesity (age: 31 ± 6 years; body mass index: 33 ± 3 kg/m2) completed 12 weeks (4 sessions/week) of either HIIT (10 × 1-minute at 90%HRmax, 1-minute active recovery; n = 16) or MICT (45 minutes at 70%HRmax; n = 15). To assess the direct effects of exercise independent of weight/fat loss, participants were required to maintain body mass. RESULTS Training increased peak oxygen uptake by ~10% in both HIIT and MICT (P < 0.0001), and body weight/fat mass were unchanged. Peripheral insulin sensitivity (hyperinsulinemic-euglycemic clamp) was ~20% greater the day after the final exercise session compared to pretraining (P < 0.01), with no difference between HIIT and MICT. When trained participants abstained from exercise for 4 days, insulin sensitivity returned to pretraining levels in both groups. HIIT and MICT also induced similar increases in abundance of many skeletal muscle proteins involved in mitochondrial respiration and lipid and carbohydrate metabolism. Training-induced alterations in muscle lipid profile were also similar between groups. CONCLUSION Despite large differences in training intensity and exercise time, 12 weeks of HIIT and MICT induce similar acute improvements in peripheral insulin sensitivity the day after exercise, and similar longer term metabolic adaptations in skeletal muscle in adults with obesity. These findings support the notion that the insulin-sensitizing effects of both HIIT and MICT are mediated by factors stemming from the most recent exercise session(s) rather than adaptations that accrue with training.
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Affiliation(s)
- Benjamin J Ryan
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Michael W Schleh
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Cheehoon Ahn
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Alison C Ludzki
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Jenna B Gillen
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Pallavi Varshney
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Douglas W Van Pelt
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Lisa M Pitchford
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | | | - Rachel A Gioscia-Ryan
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Suzette M Howton
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Thomas Rode
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Scott L Hummel
- Division of Cardiology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
- Ann Arbor Veterans Affairs Health System, Ann Arbor, Michigan
| | - Charles F Burant
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Jonathan P Little
- School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, British Columbia, Canada
| | - Jeffrey F Horowitz
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
- Correspondence and Reprint Requests: Jeffrey F. Horowitz, PhD, School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI, USA 48109-2214.
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28
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Dantas WS, Roschel H, Murai IH, Gil S, Davuluri G, Axelrod CL, Ghosh S, Newman SS, Zhang H, Shinjo SK, das Neves W, Merege-Filho C, Teodoro WR, Capelozzi VL, Pereira RM, Benatti FB, de Sá-Pinto AL, de Cleva R, Santo MA, Kirwan JP, Gualano B. Exercise-Induced Increases in Insulin Sensitivity After Bariatric Surgery Are Mediated By Muscle Extracellular Matrix Remodeling. Diabetes 2020; 69:1675-1691. [PMID: 32409493 PMCID: PMC7372074 DOI: 10.2337/db19-1180] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/08/2020] [Indexed: 02/06/2023]
Abstract
Exercise seems to enhance the beneficial effect of bariatric (Roux-en-Y gastric bypass [RYGB]) surgery on insulin resistance. We hypothesized that skeletal muscle extracellular matrix (ECM) remodeling may underlie these benefits. Women were randomized to either a combined aerobic and resistance exercise training program following RYGB (RYGB + ET) or standard of care (RYGB). Insulin sensitivity was assessed by oral glucose tolerance test. Muscle biopsy specimens were obtained at baseline and 3 and 9 months after surgery and subjected to comprehensive phenotyping, transcriptome profiling, molecular pathway identification, and validation in vitro. Exercise training improved insulin sensitivity beyond surgery alone (e.g., Matsuda index: RYGB 123% vs. RYGB + ET 325%; P ≤ 0.0001). ECM remodeling was reduced by surgery alone, with an additive benefit of surgery and exercise training (e.g., collagen I: RYGB -41% vs. RYGB + ET -76%; P ≤ 0.0001). Exercise and RYGB had an additive effect on enhancing insulin sensitivity, but surgery alone did not resolve insulin resistance and ECM remodeling. We identified candidates modulated by exercise training that may become therapeutic targets for treating insulin resistance, in particular, the transforming growth factor-β1/SMAD 2/3 pathway and its antagonist follistatin. Exercise-induced increases in insulin sensitivity after bariatric surgery are at least partially mediated by muscle ECM remodeling.
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Affiliation(s)
- Wagner S Dantas
- Integrated Physiology and Molecular Metabolism Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Laboratory of Assessment and Conditioning in Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Hamilton Roschel
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Laboratory of Assessment and Conditioning in Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
- Rheumatology Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Igor H Murai
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Laboratory of Assessment and Conditioning in Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Saulo Gil
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Laboratory of Assessment and Conditioning in Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Gangarao Davuluri
- Integrated Physiology and Molecular Metabolism Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
| | - Christopher L Axelrod
- Integrated Physiology and Molecular Metabolism Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
- Department of Translational Services, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
| | - Sujoy Ghosh
- Genomics Core, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
- Cardiovascular and Metabolic Disorders Program and Center for Computational Biology, Duke-National University of Singapore Medical School, Singapore
| | - Susan S Newman
- Genomics Core, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
| | - Hui Zhang
- Integrated Physiology and Molecular Metabolism Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
| | - Samuel K Shinjo
- Rheumatology Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Willian das Neves
- Clinical Oncology Service, Instituto do Câncer do Estado de São Paulo, São Paulo, Brazil
| | - Carlos Merege-Filho
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Laboratory of Assessment and Conditioning in Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Walcy R Teodoro
- Rheumatology Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Vera L Capelozzi
- Department of Pathology, School of Medicine, Universidade de São Paulo, São Paulo, Brazil
| | - Rosa Maria Pereira
- Rheumatology Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Fabiana B Benatti
- School of Applied Sciences, Universidade Estadual de Campinas, São Paulo, Brazil
| | - Ana L de Sá-Pinto
- Rheumatology Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Roberto de Cleva
- Department of Digestive Division, School of Medicine, Universidade de São Paulo, São Paulo, Brazil
| | - Marco A Santo
- Department of Digestive Division, School of Medicine, Universidade de São Paulo, São Paulo, Brazil
| | - John P Kirwan
- Integrated Physiology and Molecular Metabolism Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA
| | - Bruno Gualano
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Laboratory of Assessment and Conditioning in Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
- Rheumatology Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
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29
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Low-Intensity Exercise Training Additionally Increases Mitochondrial Dynamics Caused by High-Fat Diet (HFD) but Has No Additional Effect on Mitochondrial Biogenesis in Fast-Twitch Muscle by HFD. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17155461. [PMID: 32751208 PMCID: PMC7432492 DOI: 10.3390/ijerph17155461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 01/07/2023]
Abstract
This study examines how the high-fat diet (HFD) affects mitochondrial dynamics and biogenesis, and also whether combining it with low-intensity endurance exercise adds to these effects. Six 8-week-old male Sprague–Dawley (SD) rats were put on control (CON; standard chow diet), HF (HFD intake), and HFEx (HFD + low-intensity treadmill exercise) for 6 weeks. As a result, no change in body weight was observed among the groups. However, epididymal fat mass increased significantly in the two groups that had been given HFD. Blood free fatty acid (FFA) also increased significantly in the HF group. While HFD increased insulin resistance (IR), this was improved significantly in the HFEx group. HFD also significantly increased mitochondrial biogenesis-related factors (PPARδ, PGC-1α, and mtTFA) and mitochondrial electron transport chain proteins; however, no additional effect from exercise was observed. Mitochondrial dynamic-related factors were also affected: Mfn2 increased significantly in the HFEx group, while Drp1 and Fis-1 increased significantly in both the HF and HFEx groups. The number of mitochondria in the subsarcolemmal region, and their size in the subsarcolemmal and intermyofibrillar regions, also increased significantly in the HFEx group. Taken overall, these results show that HFD in combination with low-intensity endurance exercise has no additive effect on mitochondrial biogenesis, although it does have such an effect on mitochondrial dynamics by improving IR.
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30
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Lai N, Fealy CE, Kummitha CM, Cabras S, Kirwan JP, Hoppel CL. Mitochondrial Utilization of Competing Fuels Is Altered in Insulin Resistant Skeletal Muscle of Non-obese Rats (Goto-Kakizaki). Front Physiol 2020; 11:677. [PMID: 32612543 PMCID: PMC7308651 DOI: 10.3389/fphys.2020.00677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 05/26/2020] [Indexed: 12/25/2022] Open
Abstract
Aim Insulin-resistant skeletal muscle is characterized by metabolic inflexibility with associated alterations in substrate selection, mediated by peroxisome-proliferator activated receptor δ (PPARδ). Although it is established that PPARδ contributes to the alteration of energy metabolism, it is not clear whether it plays a role in mitochondrial fuel competition. While nutrient overload may impair metabolic flexibility by fuel congestion within mitochondria, in absence of obesity defects at a mitochondrial level have not yet been excluded. We sought to determine whether reduced PPARδ content in insulin-resistant rat skeletal muscle of a non-obese rat model of T2DM (Goto-Kakizaki, GK) ameliorate the inhibitory effect of fatty acid (i.e., palmitoylcarnitine) on mitochondrial carbohydrate oxidization (i.e., pyruvate) in muscle fibers. Methods Bioenergetic function was characterized in oxidative soleus (S) and glycolytic white gastrocnemius (WG) muscles with measurement of respiration rates in permeabilized fibers in the presence of complex I, II, IV, and fatty acid substrates. Mitochondrial content was measured by citrate synthase (CS) and succinate dehydrogenase activity (SDH). Western blot was used to determine protein expression of PPARδ, PDK isoform 2 and 4. Results CS and SDH activity, key markers of mitochondrial content, were reduced by ∼10-30% in diabetic vs. control, and the effect was evident in both oxidative and glycolytic muscles. PPARδ (p < 0.01), PDK2 (p < 0.01), and PDK4 (p = 0.06) protein content was reduced in GK animals compared to Wistar rats (N = 6 per group). Ex vivo respiration rates in permeabilized muscle fibers determined in the presence of complex I, II, IV, and fatty acid substrates, suggested unaltered mitochondrial bioenergetic function in T2DM muscle. Respiration in the presence of pyruvate was higher compared to palmitoylcarnitine in both animal groups and fiber types. Moreover, respiration rates in the presence of both palmitoylcarnitine and pyruvate were reduced by 25 ± 6% (S), 37 ± 6% (WG) and 63 ± 6% (S), 57 ± 8% (WG) compared to pyruvate for both controls and GK, respectively. The inhibitory effect of palmitoylcarnitine on respiration was significantly greater in GK than controls (p < 10-3). Conclusion With competing fuels, the presence of fatty acids diminishes mitochondria ability to utilize carbohydrate derived substrates in insulin-resistant muscle despite reduced PPARδ content.
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Affiliation(s)
- Nicola Lai
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, United States.,Biomedical Engineering Institute, Old Dominion University, Norfolk, VA, United States.,Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Cagliari, Italy.,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States.,Center for Mitochondrial Disease, Case Western Reserve University, Cleveland, OH, United States
| | - Ciarán E Fealy
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Chinna M Kummitha
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Silvia Cabras
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - John P Kirwan
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.,Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, United States.,Pennington Biomedical Research Center, Baton Rouge, LA, United States
| | - Charles L Hoppel
- Center for Mitochondrial Disease, Case Western Reserve University, Cleveland, OH, United States.,Department of Pharmacology, Case Western Reserve University, Cleveland, OH, United States.,Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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Dubé JJ, Collyer ML, Trant S, Toledo FGS, Goodpaster BH, Kershaw EE, DeLany JP. Decreased Mitochondrial Dynamics Is Associated with Insulin Resistance, Metabolic Rate, and Fitness in African Americans. J Clin Endocrinol Metab 2020; 105:dgz272. [PMID: 31833547 PMCID: PMC7067552 DOI: 10.1210/clinem/dgz272] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/11/2019] [Indexed: 12/27/2022]
Abstract
CONTEXT African American women (AAW) have a higher incidence of insulin resistance and are at a greater risk for the development of obesity and type 2 diabetes than Caucasian women (CW). Although several factors have been proposed to mediate these racial disparities, the mechanisms remain poorly defined. We previously demonstrated that sedentary lean AAW have lower peripheral insulin sensitivity, reduced maximal aerobic fitness (VO2max), and lower resting metabolic rate (RMR) than CW. We have also demonstrated that skeletal muscle mitochondrial respiration is lower in AAW and appears to play a role in these racial differences. OBJECTIVE The goal of this study was to assess mitochondrial pathways and dynamics to examine the potential mechanisms of lower insulin sensitivity, RMR, VO2max, and mitochondrial capacity in AAW. DESIGN To achieve this goal, we assessed several mitochondrial pathways in skeletal muscle using gene array technology and semiquantitative protein analysis. RESULTS We report alterations in mitochondrial pathways associated with inner membrane small molecule transport genes, fusion-fission, and autophagy in lean AAW. These differences were associated with lower insulin sensitivity, RMR, and VO2max. CONCLUSIONS Together these data suggest that the metabolic racial disparity of insulin resistance, RMR, VO2max, and mitochondrial capacity may be mediated by perturbations in mitochondrial pathways associated with membrane transport, fission-fusion, and autophagy. The mechanisms contributing to these differences remain unknown.
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Affiliation(s)
- John J Dubé
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- School of Arts, Business, and Science, Department of Biology, Chatham University, Pittsburgh, Pennsylvania
| | - Michael L Collyer
- School of Arts, Business, and Science, Department of Biology, Chatham University, Pittsburgh, Pennsylvania
| | - Sara Trant
- School of Arts, Business, and Science, Department of Biology, Chatham University, Pittsburgh, Pennsylvania
| | - Frederico G S Toledo
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Bret H Goodpaster
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Erin E Kershaw
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - James P DeLany
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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Jones S, Tillin T, Williams S, Eastwood SV, Hughes AD, Chaturvedi N. Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults. Diabetologia 2020; 63:624-635. [PMID: 31820039 PMCID: PMC6997264 DOI: 10.1007/s00125-019-05055-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/29/2019] [Indexed: 01/14/2023]
Abstract
AIMS/HYPOTHESIS The aim of this study was to compare exercise capacity, strength and skeletal muscle perfusion during exercise, and oxidative capacity between South Asians, African Caribbeans and Europeans, and determine what effect ethnic differences in the prevalence of type 2 diabetes has on these functional outcomes. METHODS In total, 708 participants (aged [mean±SD] 73 ± 7 years, 56% male) were recruited from the Southall and Brent Revisited (SABRE) study, a UK population-based cohort comprised of Europeans (n = 311) and South Asian (n = 232) and African Caribbean (n = 165) migrants. Measurements of exercise capacity using a 6 min stepper test (6MST), including measurement of oxygen consumption ([Formula: see text]) and grip strength, were performed. Skeletal muscle was assessed using near infrared spectroscopy (NIRS); measures included changes in tissue saturation index (∆TSI%) with exercise and oxidative capacity (muscle oxygen consumption recovery, represented by a time constant [τ]). Analysis was by multiple linear regression. RESULTS When adjusted for age and sex, in South Asians and African Caribbeans, exercise capacity was reduced compared with Europeans ([Formula: see text] [ml min-1 kg-1]: β = -1.2 [95% CI -1.9, -0.4], p = 0.002, and β -1.7 [95% CI -2.5, -0.8], p < 0.001, respectively). South Asians had lower and African Caribbeans had higher strength compared with Europeans (strength [kPa]: β = -9 [95% CI -12, -6), p < 0.001, and β = 6 [95% CI 3, 9], p < 0.001, respectively). South Asians had greater decreases in TSI% and longer τ compared with Europeans (∆TSI% [%]: β = -0.9 [95% CI -1.7, -0.1), p = 0.024; τ [s]: β = 11 [95% CI 3, 18], p = 0.006). Ethnic differences in [Formula: see text] and grip strength remained despite adjustment for type 2 diabetes or HbA1c (and fat-free mass for grip strength). However, the differences between Europeans and South Asians were no longer statistically significant after adjustment for other possible mediators or confounders (including physical activity, waist-to-hip ratio, cardiovascular disease or hypertension, smoking, haemoglobin levels or β-blocker use). The difference in ∆TSI% between Europeans and South Asians was marginally attenuated after adjustment for type 2 diabetes or HbA1c and was also no longer statistically significant after adjusting for other confounders; however, τ remained significantly longer in South Asians vs Europeans despite adjustment for all confounders. CONCLUSIONS/INTERPRETATION Reduced exercise capacity in South Asians and African Caribbeans is unexplained by higher rates of type 2 diabetes. Poorer exercise tolerance in these populations, and impaired muscle function and perfusion in South Asians, may contribute to the higher morbidity burden of UK ethnic minority groups in older age.
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Affiliation(s)
- Siana Jones
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Therese Tillin
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Suzanne Williams
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Sophie V Eastwood
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Alun D Hughes
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Nishi Chaturvedi
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, Gower Street, London, WC1E 6BT, UK
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Reduced Glucose Tolerance and Skeletal Muscle GLUT4 and IRS1 Content in Cyclists Habituated to a Long-Term Low-Carbohydrate, High-Fat Diet. Int J Sport Nutr Exerc Metab 2020; 30:210–217. [PMID: 32109885 DOI: 10.1123/ijsnem.2019-0359] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/03/2020] [Accepted: 02/03/2020] [Indexed: 11/18/2022]
Abstract
Very little is known about how long-term (>6 months) adaptation to a low-carbohydrate, high-fat (LCHF) diet affects insulin signaling in healthy, well-trained individuals. This study compared glucose tolerance; skeletal muscle glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) content; and muscle enzyme activities representative of the main energy pathways (3-hydroxyacetyl-CoA dehydrogenase, creatine kinase, citrate synthase, lactate dehydrogenase, phosphofructokinase, phosphorylase) in trained cyclists who followed either a long-term LCHF or a mixed-macronutrient (Mixed) diet. On separate days, a 2-hr oral glucose tolerance test was conducted, and muscle samples were obtained from the vastus lateralis of fasted participants. The LCHF group had reduced glucose tolerance compared with the Mixed group, as plasma glucose concentrations were significantly higher throughout the oral glucose tolerance test and serum insulin concentrations peaked later (LCHF, 60 min; Mixed, 30 min). Whole-body insulin sensitivity was not statistically significantly different between groups (Matsuda index: LCHF, 8.7 ± 3.4 vs. Mixed, 12.9 ± 4.6; p = .08). GLUT4 (LCHF: 1.13 ± 0.24; Mixed: 1.44 ± 0.16; p = .026) and IRS1 (LCHF: 0.25 ± 0.13; Mixed: 0.46 ± 0.09; p = .016) protein content was lower in LCHF muscle, but enzyme activities were not different. We conclude that well-trained cyclists habituated to an LCHF diet had reduced glucose tolerance compared with matched controls on a mixed diet. Lower skeletal muscle GLUT4 and IRS1 contents may partially explain this finding. This could possibly reflect an adaptation to reduced habitual glucose availability rather than the development of a pathological insulin resistance.
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Masschelin PM, Cox AR, Chernis N, Hartig SM. The Impact of Oxidative Stress on Adipose Tissue Energy Balance. Front Physiol 2020; 10:1638. [PMID: 32038305 PMCID: PMC6987041 DOI: 10.3389/fphys.2019.01638] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 12/30/2019] [Indexed: 12/21/2022] Open
Abstract
Overnutrition and sedentary activity reinforce the growing trend of worldwide obesity, insulin resistance, and type 2 diabetes. However, we have limited insight into how food intake generates sophisticated metabolic perturbations associated with obesity. Accumulation of mitochondrial oxidative stress contributes to the metabolic changes in obesity, but the mechanisms and significance are unclear. In white adipose tissue (WAT), mitochondrial oxidative stress, and the generation of reactive oxygen species (ROS) impact the endocrine and metabolic function of fat cells. The central role of mitochondria in nutrient handling suggests pharmacological targeting of pathological oxidative stress likely improves the metabolic profile of obesity. This review will summarize the critical pathogenic mechanisms of obesity-driven oxidative stress in WAT.
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Affiliation(s)
- Peter M Masschelin
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, United States.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States
| | - Aaron R Cox
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Natasha Chernis
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Sean M Hartig
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, United States.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States
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Denisenko YK, Kytikova OY, Novgorodtseva TP, Antonyuk MV, Gvozdenko TA, Kantur TA. Lipid-Induced Mechanisms of Metabolic Syndrome. J Obes 2020; 2020:5762395. [PMID: 32963827 PMCID: PMC7491450 DOI: 10.1155/2020/5762395] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/23/2020] [Accepted: 07/30/2020] [Indexed: 12/23/2022] Open
Abstract
Metabolic syndrome (MetS) has a worldwide tendency to increase and depends on many components, which explains the complexity of diagnosis, approaches to the prevention, and treatment of this pathology. Insulin resistance (IR) is the crucial cause of the MetS pathogenesis, which develops against the background of abdominal obesity. In light of recent evidence, it has been shown that lipids, especially fatty acids (FAs), are important signaling molecules that regulate the signaling pathways of insulin and inflammatory mediators. On the one hand, the lack of n-3 polyunsaturated fatty acids (PUFAs) in the body leads to impaired molecular mechanisms of glucose transport, the formation of unresolved inflammation. On the other hand, excessive formation of free fatty acids (FFAs) underlies the development of oxidative stress and mitochondrial dysfunction in MetS. Understanding the molecular mechanisms of the participation of FAs and their metabolites in the pathogenesis of MetS will contribute to the development of new diagnostic methods and targeted therapy for this disease. The purpose of this review is to highlight recent advances in the study of the effect of fatty acids as modulators of insulin response and inflammatory process in the pathogenesis and treatment for MetS.
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Affiliation(s)
- Yulia K. Denisenko
- Vladivostok Branch of the Far Eastern Scientific Centre of Physiology and Pathology of Respiration, Institute of Medical Climatology and Rehabilitative Treatment, Vladivostok 690105, Russia
| | - Oxana Yu Kytikova
- Vladivostok Branch of the Far Eastern Scientific Centre of Physiology and Pathology of Respiration, Institute of Medical Climatology and Rehabilitative Treatment, Vladivostok 690105, Russia
| | - Tatyana P. Novgorodtseva
- Vladivostok Branch of the Far Eastern Scientific Centre of Physiology and Pathology of Respiration, Institute of Medical Climatology and Rehabilitative Treatment, Vladivostok 690105, Russia
| | - Marina V. Antonyuk
- Vladivostok Branch of the Far Eastern Scientific Centre of Physiology and Pathology of Respiration, Institute of Medical Climatology and Rehabilitative Treatment, Vladivostok 690105, Russia
| | - Tatyana A. Gvozdenko
- Vladivostok Branch of the Far Eastern Scientific Centre of Physiology and Pathology of Respiration, Institute of Medical Climatology and Rehabilitative Treatment, Vladivostok 690105, Russia
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Abstract
Obesity and type 2 diabetes are the most frequent metabolic disorders, but their causes remain largely unclear. Insulin resistance, the common underlying abnormality, results from imbalance between energy intake and expenditure favouring nutrient-storage pathways, which evolved to maximize energy utilization and preserve adequate substrate supply to the brain. Initially, dysfunction of white adipose tissue and circulating metabolites modulate tissue communication and insulin signalling. However, when the energy imbalance is chronic, mechanisms such as inflammatory pathways accelerate these abnormalities. Here we summarize recent studies providing insights into insulin resistance and increased hepatic gluconeogenesis associated with obesity and type 2 diabetes, focusing on data from humans and relevant animal models.
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37
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Nisr RB, Shah DS, Ganley IG, Hundal HS. Proinflammatory NFkB signalling promotes mitochondrial dysfunction in skeletal muscle in response to cellular fuel overloading. Cell Mol Life Sci 2019; 76:4887-4904. [PMID: 31101940 PMCID: PMC6881256 DOI: 10.1007/s00018-019-03148-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 11/29/2022]
Abstract
Sustained nutrient (fuel) excess, as occurs during obesity and diabetes, has been linked to increased inflammation, impaired mitochondrial homeostasis, lipotoxicity, and insulin resistance in skeletal muscle. Precisely how mitochondrial dysfunction is initiated and whether it contributes to insulin resistance in this tissue remains a poorly resolved issue. Herein, we examine the contribution that an increase in proinflammatory NFkB signalling makes towards regulation of mitochondrial bioenergetics, morphology, and dynamics and its impact upon insulin action in skeletal muscle cells subject to chronic fuel (glucose and palmitate) overloading. We show sustained nutrient excess of L6 myotubes promotes activation of the IKKβ-NFkB pathway (as judged by a six-fold increase in IL-6 mRNA expression; an NFkB target gene) and that this was associated with a marked reduction in mitochondrial respiratory capacity (>50%), a three-fold increase in mitochondrial fragmentation and 2.5-fold increase in mitophagy. Under these circumstances, we also noted a reduction in the mRNA and protein abundance of PGC1α and that of key mitochondrial components (SDHA, ANT-1, UCP3, and MFN2) as well as an increase in cellular ROS and impaired insulin action in myotubes. Strikingly, pharmacological or genetic repression of NFkB activity ameliorated disturbances in mitochondrial respiratory function/morphology, attenuated loss of SDHA, ANT-1, UCP3, and MFN2 and mitigated the increase in ROS and the associated reduction in myotube insulin sensitivity. Our findings indicate that sustained oversupply of metabolic fuel to skeletal muscle cells induces heightened NFkB signalling and that this serves as a critical driver for disturbances in mitochondrial function and morphology, redox status, and insulin signalling.
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Affiliation(s)
- Raid B Nisr
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Dinesh S Shah
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Ian G Ganley
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
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38
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Pino MF, Stephens NA, Eroshkin AM, Yi F, Hodges A, Cornnell HH, Pratley RE, Smith SR, Wang M, Han X, Coen PM, Goodpaster BH, Sparks LM. Endurance training remodels skeletal muscle phospholipid composition and increases intrinsic mitochondrial respiration in men with Type 2 diabetes. Physiol Genomics 2019; 51:586-595. [PMID: 31588872 DOI: 10.1152/physiolgenomics.00014.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The effects of exercise training on the skeletal muscle (SKM) lipidome and mitochondrial function have not been thoroughly explored in individuals with Type 2 diabetes (T2D). We hypothesize that 10 wk of supervised endurance training improves SKM mitochondrial function and insulin sensitivity that are related to alterations in lipid signatures within SKM of T2D (males n = 8). We employed integrated multi-omics data analyses including ex vivo lipidomics (MS/MS-shotgun) and transcriptomics (RNA-Seq). From biopsies of SKM, tissue and primary myotubes mitochondrial respiration were quantified by high-resolution respirometry. We also performed hyperinsulinemic-euglycemic clamps and blood draws before and after the training. The lipidomics analysis revealed that endurance training (>95% compliance) increased monolysocardiolipin by 68.2% (P ≤ 0.03), a putative marker of mitochondrial remodeling, and reduced total sphingomyelin by 44.8% (P ≤ 0.05) and phosphatidylserine by 39.7% (P ≤ 0.04) and tended to reduce ceramide lipid content by 19.8%. Endurance training also improved intrinsic mitochondrial respiration in SKM of T2D without alterations in mitochondrial DNA copy number or cardiolipin content. RNA-Seq revealed 71 transcripts in SKM of T2D that were differentially regulated. Insulin sensitivity was unaffected, and HbA1c levels moderately increased by 7.3% despite an improvement in cardiorespiratory fitness (V̇o2peak) following the training intervention. In summary, endurance training improves intrinsic and cell-autonomous SKM mitochondrial function and modifies lipid composition in men with T2D independently of alterations in insulin sensitivity and glycemic control.
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Affiliation(s)
- Maria F Pino
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Natalie A Stephens
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Alexey M Eroshkin
- Sanford Burnham Prebys Medical Discovery Institute, Torrey Pines, California
| | - Fanchao Yi
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Andrew Hodges
- Sanford Burnham Prebys Medical Discovery Institute, Torrey Pines, California
| | - Heather H Cornnell
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Richard E Pratley
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Steven R Smith
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Miao Wang
- University of Texas Health Sciences Center San Antonio, San Antonio, Texas
| | - Xianlin Han
- University of Texas Health Sciences Center San Antonio, San Antonio, Texas
| | - Paul M Coen
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Bret H Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Lauren M Sparks
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
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Fu T, Xu Z, Liu L, Guo Q, Wu H, Liang X, Zhou D, Xiao L, Liu L, Liu Y, Zhu MS, Chen Q, Gan Z. Mitophagy Directs Muscle-Adipose Crosstalk to Alleviate Dietary Obesity. Cell Rep 2019; 23:1357-1372. [PMID: 29719250 DOI: 10.1016/j.celrep.2018.03.127] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 02/07/2018] [Accepted: 03/28/2018] [Indexed: 12/17/2022] Open
Abstract
The quality of mitochondria in skeletal muscle is essential for maintaining metabolic homeostasis during adaptive stress responses. However, the precise control mechanism of muscle mitochondrial quality and its physiological impacts remain unclear. Here, we demonstrate that FUNDC1, a mediator of mitophagy, plays a critical role in controlling muscle mitochondrial quality as well as metabolic homeostasis. Skeletal-muscle-specific ablation of FUNDC1 in mice resulted in LC3-mediated mitophagy defect, leading to impaired mitochondrial energetics. This caused decreased muscle fat utilization and endurance capacity during exercise. Interestingly, mice lacking muscle FUNDC1 were protected against high-fat-diet-induced obesity with improved systemic insulin sensitivity and glucose tolerance despite reduced muscle mitochondrial energetics. Mechanistically, FUNDC1 deficiency elicited a retrograde response in muscle that upregulated FGF21 expression, thereby promoting the thermogenic remodeling of adipose tissue. Thus, these findings reveal a pivotal role of FUNDC1-dependent mitochondrial quality control in mediating the muscle-adipose dialog to regulate systemic metabolism.
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Affiliation(s)
- Tingting Fu
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Zhisheng Xu
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Lin Liu
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Qiqi Guo
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Hao Wu
- The State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xijun Liang
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Danxia Zhou
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Liwei Xiao
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Lei Liu
- The State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yong Liu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Min-Sheng Zhu
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Quan Chen
- The State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Zhenji Gan
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China.
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Abstract
The cause of insulin resistance in obesity and type 2 diabetes mellitus (T2DM) is not limited to impaired insulin signalling but also involves the complex interplay of multiple metabolic pathways. The analysis of large data sets generated by metabolomics and lipidomics has shed new light on the roles of metabolites such as lipids, amino acids and bile acids in modulating insulin sensitivity. Metabolites can regulate insulin sensitivity directly by modulating components of the insulin signalling pathway, such as insulin receptor substrates (IRSs) and AKT, and indirectly by altering the flux of substrates through multiple metabolic pathways, including lipogenesis, lipid oxidation, protein synthesis and degradation and hepatic gluconeogenesis. Moreover, the post-translational modification of proteins by metabolites and lipids, including acetylation and palmitoylation, can alter protein function. Furthermore, the role of the microbiota in regulating substrate metabolism and insulin sensitivity is unfolding. In this Review, we discuss the emerging roles of metabolites in the pathogenesis of insulin resistance and T2DM. A comprehensive understanding of the metabolic adaptations involved in insulin resistance may enable the identification of novel targets for improving insulin sensitivity and preventing, and treating, T2DM.
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Mitochondrial Activity and Skeletal Muscle Insulin Resistance in Kidney Disease. Int J Mol Sci 2019; 20:ijms20112751. [PMID: 31195596 PMCID: PMC6600571 DOI: 10.3390/ijms20112751] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 05/28/2019] [Accepted: 06/04/2019] [Indexed: 12/17/2022] Open
Abstract
Insulin resistance is a key feature of the metabolic syndrome, a cluster of medical disorders that together increase the chance of developing type 2 diabetes and cardiovascular disease. In turn, type 2 diabetes may cause complications such as diabetic kidney disease (DKD). Obesity is a major risk factor for developing systemic insulin resistance, and skeletal muscle is the first tissue in susceptible individuals to lose its insulin responsiveness. Interestingly, lean individuals are not immune to insulin resistance either. Non-obese, non-diabetic subjects with chronic kidney disease (CKD), for example, exhibit insulin resistance at the very onset of CKD, even before clinical symptoms of renal failure are clear. This uraemic insulin resistance contributes to the muscle weakness and muscle wasting that many CKD patients face, especially during the later stages of the disease. Bioenergetic failure has been associated with the loss of skeletal muscle insulin sensitivity in obesity and uraemia, as well as in the development of kidney disease and its sarcopenic complications. In this mini review, we evaluate how mitochondrial activity of different renal cell types changes during DKD progression, and discuss the controversial role of oxidative stress and mitochondrial reactive oxygen species in DKD. We also compare the involvement of skeletal muscle mitochondria in uraemic and obesity-related muscle insulin resistance.
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Mohajeri M, Martín-Jiménez C, Barreto GE, Sahebkar A. Effects of estrogens and androgens on mitochondria under normal and pathological conditions. Prog Neurobiol 2019; 176:54-72. [DOI: 10.1016/j.pneurobio.2019.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 02/23/2019] [Accepted: 03/05/2019] [Indexed: 02/06/2023]
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Axelrod CL, Fealy CE, Mulya A, Kirwan JP. Exercise training remodels human skeletal muscle mitochondrial fission and fusion machinery towards a pro-elongation phenotype. Acta Physiol (Oxf) 2019; 225:e13216. [PMID: 30408342 DOI: 10.1111/apha.13216] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 12/12/2022]
Abstract
AIMS Mitochondria exist as a morphologically plastic network driven by cellular bioenergetic demand. Induction of fusion and fission machinery allows the organelle to regulate quality control and substrate flux. Physiological stressors promote fragmentation of the mitochondrial network, a process implicated in the onset of metabolic disease, including type 2 diabetes and obesity. It is well-known that exercise training improves skeletal muscle mitochondrial volume, number, and density. However, the effect of exercise training on muscle mitochondrial dynamics remains unclear. METHODS Ten sedentary adults (65.8 ± 4.6 years; 34.3 ± 2.4 kg/m2 ) underwent 12 weeks of supervised aerobic exercise training (5 day/wk, 85% of HRMAX ). Body composition, cardio-metabolic testing, hyperinsulinaemic-euglycaemic clamps, and skeletal muscle biopsies were performed before and after training. MFN1, MFN2, OPA1, OMA1, FIS1, Parkin, PGC-1α, and HSC70 protein expression was assessed via Western blot. RESULTS Exercise training led to improvements in insulin sensitivity, aerobic capacity, and fat oxidation (all P < 0.01), as well as reductions in body weight, BMI, fat mass and fasting glucose (all P < 0.001). When normalized for changes in mitochondrial content, exercise reduced skeletal muscle FIS1 and Parkin (P < 0.05), while having no significant effect on MFN1, MFN2, OPA1, and OMA1 expression. Exercise also improved the ratio of fusion to fission proteins (P < 0.05), which positively correlated with improvements in glucose disposal (r2 = 0.59, P < 0.05). CONCLUSIONS Exercise training alters the expression of mitochondrial fusion and fission proteins, promoting a more fused, tubular network. These changes may contribute to the improvements in insulin sensitivity and substrate utilization that are observed after exercise training.
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Affiliation(s)
- Christopher L. Axelrod
- Department of Pathobiology, Lerner Research Institute Cleveland Clinic Cleveland Ohio
- Integrated Physiology and Molecular Medicine Laboratory Pennington Biomedical Research Center Baton Rouge Louisiana
| | - Ciarán E. Fealy
- Department of Pathobiology, Lerner Research Institute Cleveland Clinic Cleveland Ohio
| | - Anny Mulya
- Department of Pathobiology, Lerner Research Institute Cleveland Clinic Cleveland Ohio
| | - John P. Kirwan
- Department of Pathobiology, Lerner Research Institute Cleveland Clinic Cleveland Ohio
- Integrated Physiology and Molecular Medicine Laboratory Pennington Biomedical Research Center Baton Rouge Louisiana
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Ren J, Sherry AD, Malloy CR. Modular 31 P wideband inversion transfer for integrative analysis of adenosine triphosphate metabolism, T 1 relaxation and molecular dynamics in skeletal muscle at 7T. Magn Reson Med 2019; 81:3440-3452. [PMID: 30793793 DOI: 10.1002/mrm.27686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 01/16/2019] [Accepted: 01/18/2019] [Indexed: 12/13/2022]
Abstract
PURPOSE For efficient and integrative analysis of de novo adenosine triphosphate (ATP) synthesis, creatine-kinase-mediated ATP synthesis, T1 relaxation time, and ATP molecular motion dynamics in human skeletal muscle at rest. METHODS Four inversion-transfer modules differing in center inversion frequency were combined to generate amplified magnetization transfer (MT) effects in targeted MT pathways, including Pi ↔ γ-ATP, PCr ↔ γ-ATP, and 31 Pγ(α)ATP ↔ 31 PβATP . MT effects from both forward and reverse exchange kinetic pathways were acquired to reduce potential bias and confounding factors in integrated data analysis. RESULTS Kinetic data collected using 4 wideband inversion modules (8 minutes each) yielded the forward exchange rate constants, kPCr →γ ATP = 0.31 ± 0.05 s-1 and kPi →γ ATP = 0.064 ± 0.012 s-1 , and the reverse exchange rate constants, kγATP→Pi = 0.034 ± 0.006 s-1 and kγATP→PCr = 1.37 ± 0.22 s-1 , respectively. The cross-relaxation rate constant, σγ(α) ↔ βATP was -0.20 ± 0.03 s-1 , corresponding to ATP rotational correlation time τc of 0.8 ± 0.1 × 10-7 seconds. The intrinsic T1 relaxation times were Pi (9.2 ± 1.4 seconds), PCr (6.2 ± 0.4 seconds), γ-ATP (1.8 ± 0.1 seconds), α-ATP (1.4 ± 0.1 seconds), and β-ATP (1.1 ± 0.1 seconds). Muscle ATP T1 values were found to be significantly longer than those previously measured in the brain using a similar method. CONCLUSION A combination of multiple inversion transfer modules provides a comprehensive and integrated analysis of ATP metabolism and molecular motion dynamics. This relatively fast technique could be potentially useful for studying metabolic disorders in skeletal muscle.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Chemistry, University of Texas at Dallas, Richardson, Texas
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,VA North Texas Health Care System, Dallas, Texas
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Jana BA, Chintamaneni PK, Krishnamurthy PT, Wadhwani A, Mohankumar SK. Cytosolic lipid excess-induced mitochondrial dysfunction is the cause or effect of high fat diet-induced skeletal muscle insulin resistance: a molecular insight. Mol Biol Rep 2018; 46:957-963. [DOI: 10.1007/s11033-018-4551-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 11/30/2018] [Indexed: 12/30/2022]
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Falcão-Tebas F, Kuang J, Arceri C, Kerris JP, Andrikopoulos S, Marin EC, McConell GK. Four weeks of exercise early in life reprograms adult skeletal muscle insulin resistance caused by a paternal high-fat diet. J Physiol 2018; 597:121-136. [PMID: 30406963 DOI: 10.1113/jp276386] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 10/05/2018] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS A paternal high-fat diet/obesity before mating can negatively influence the metabolism of offspring. Exercise only early in life has a remarkable effect with respect to reprogramming adult rat offspring exposed to detrimental insults before conception. Exercise only early in life normalized adult whole body and muscle insulin resistance as a result of having a high-fat fed/obese father. Unlike the effects on the muscle, early exercise did not normalize the reduced adult pancreatic beta cell mass as a result of having a high-fat fed/obese father. Early-life exercise training may be able to reprogram an individual whose father was obese, inducing long-lasting beneficial effects on health. ABSTRACT A paternal high-fat diet (HFD) impairs female rat offspring glucose tolerance, pancreatic morphology and insulin secretion. We examined whether only 4 weeks of exercise early in life could reprogram these negative effects. Male Sprague-Dawley rats consumed a HFD for 10 weeks before mating with chow-fed dams. Female offspring remained sedentary or performed moderate intensity treadmill exercise (5 days week-1 , 60 min day-1 , 20 m min-1 ) from 5 to 9 weeks of age. Paternal HFD impaired (P < 0.05) adult offspring whole body insulin sensitivity (i.p. insulin sensitivity test), as well as skeletal muscle ex vivo insulin sensitivity and TBC1D4 phosphorylation. It also lowered β-cell mass and reduced in vivo insulin secretion in response to an i.p. glucose tolerance test. Early-life exercise in offspring reprogrammed the negative effects of a paternal HFD on whole body insulin sensitivity, skeletal muscle ex vivo insulin-stimulated glucose uptake and TBC1D4 phosphorylation and also increased glucose transporter 4 protein. However, early exercise did not normalize the reduced pancreatic β-cell mass or insulin secretion. In conclusion, only 4 weeks of exercise early in life in female rat offspring reprograms reductions in insulin sensitivity in adulthood caused by a paternal HFD without affecting pancreatic β-cell mass or insulin secretion.
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Affiliation(s)
- Filippe Falcão-Tebas
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia.,The Ritchie Centre, Hudson Institute of Medical Research and Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Jujiao Kuang
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia
| | - Chelsea Arceri
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia
| | - Jarrod P Kerris
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia
| | - Sofianos Andrikopoulos
- Department of Medicine, Austin Hospital, The University of Melbourne, Melbourne, VIC, Australia
| | - Evelyn C Marin
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia.,Department of Medicine, Austin Hospital, The University of Melbourne, Melbourne, VIC, Australia
| | - Glenn K McConell
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia.,College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia
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Long-term follow-up of muscle lipid accumulation, mitochondrial activity and oxidative stress and their relationship with impaired glucose homeostasis in high fat high fructose diet-fed rats. J Nutr Biochem 2018; 64:182-197. [PMID: 30530258 DOI: 10.1016/j.jnutbio.2018.10.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 12/13/2022]
Abstract
Metabolic syndrome components, including obesity, dyslipidemia and impaired glucose homeostasis, become a major public health issue. Muscles play a predominant role in insulin-mediated glucose uptake, and high fat diets may negatively affect muscle function and homeostasis. This work aimed to study the time-course of muscle lipid accumulation, oxidative stress and mitochondrial dysfunction and their association to impaired glucose homeostasis in rats fed an obesogenic diet. Male Wistar rats were fed with a standard or a high fat/high fructose (HFHFr) diet and sacrificed on 4, 8, 12, 16, 20 weeks. Rats fed the HFHFr diet developed mild overweight, increased liver and adipose tissue weights and glucose intolerance. The impaired glucose homeostasis increased gradually with the HFHFr diet to become significant on the 12th and 16th weeks of diet. In parallel, the muscle lipid composition showed an increase in the saturated fatty acids and the monounsaturated fatty acids with a marked decrease in the polyunsaturated fatty acids. The HFHFr diet also increased muscle contents of both diacylglycerols and Ceramides. Surprisingly, HFHFr diet did not induce major muscle mitochondrial dysfunction or oxidative stress. These results indicate that muscle lipid alterations, as well as impaired glucose homeostasis occur as early as the 8th week of HFHFr diet, increase to reach a plateau around the 12th-16th weeks of diet, and then attenuate towards the end of study. At these diet treatment durations, muscle mitochondrial activity and oxidative stress remained unchanged and do not seem to have a major role in the observed impaired glucose homeostasis.
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Petersen MC, Shulman GI. Mechanisms of Insulin Action and Insulin Resistance. Physiol Rev 2018; 98:2133-2223. [PMID: 30067154 PMCID: PMC6170977 DOI: 10.1152/physrev.00063.2017] [Citation(s) in RCA: 1444] [Impact Index Per Article: 240.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 03/22/2018] [Accepted: 03/24/2018] [Indexed: 12/15/2022] Open
Abstract
The 1921 discovery of insulin was a Big Bang from which a vast and expanding universe of research into insulin action and resistance has issued. In the intervening century, some discoveries have matured, coalescing into solid and fertile ground for clinical application; others remain incompletely investigated and scientifically controversial. Here, we attempt to synthesize this work to guide further mechanistic investigation and to inform the development of novel therapies for type 2 diabetes (T2D). The rational development of such therapies necessitates detailed knowledge of one of the key pathophysiological processes involved in T2D: insulin resistance. Understanding insulin resistance, in turn, requires knowledge of normal insulin action. In this review, both the physiology of insulin action and the pathophysiology of insulin resistance are described, focusing on three key insulin target tissues: skeletal muscle, liver, and white adipose tissue. We aim to develop an integrated physiological perspective, placing the intricate signaling effectors that carry out the cell-autonomous response to insulin in the context of the tissue-specific functions that generate the coordinated organismal response. First, in section II, the effectors and effects of direct, cell-autonomous insulin action in muscle, liver, and white adipose tissue are reviewed, beginning at the insulin receptor and working downstream. Section III considers the critical and underappreciated role of tissue crosstalk in whole body insulin action, especially the essential interaction between adipose lipolysis and hepatic gluconeogenesis. The pathophysiology of insulin resistance is then described in section IV. Special attention is given to which signaling pathways and functions become insulin resistant in the setting of chronic overnutrition, and an alternative explanation for the phenomenon of ‟selective hepatic insulin resistanceˮ is presented. Sections V, VI, and VII critically examine the evidence for and against several putative mediators of insulin resistance. Section V reviews work linking the bioactive lipids diacylglycerol, ceramide, and acylcarnitine to insulin resistance; section VI considers the impact of nutrient stresses in the endoplasmic reticulum and mitochondria on insulin resistance; and section VII discusses non-cell autonomous factors proposed to induce insulin resistance, including inflammatory mediators, branched-chain amino acids, adipokines, and hepatokines. Finally, in section VIII, we propose an integrated model of insulin resistance that links these mediators to final common pathways of metabolite-driven gluconeogenesis and ectopic lipid accumulation.
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Affiliation(s)
- Max C Petersen
- Departments of Internal Medicine and Cellular & Molecular Physiology, Howard Hughes Medical Institute, Yale University School of Medicine , New Haven, Connecticut
| | - Gerald I Shulman
- Departments of Internal Medicine and Cellular & Molecular Physiology, Howard Hughes Medical Institute, Yale University School of Medicine , New Haven, Connecticut
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Gam CMBF, Mortensen OH, Larsen LH, Poulsen SS, Qvortrup K, Mathiesen ER, Damm P, Quistorff B. Diabetes, myometrium, and mitochondria in pregnant women at term. Acta Diabetol 2018; 55:999-1010. [PMID: 29931421 DOI: 10.1007/s00592-018-1171-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 05/28/2018] [Indexed: 12/25/2022]
Abstract
AIMS Poor myometrial contractility has been demonstrated in women at term with diabetes and decreased muscular mitochondrial content and/or function has been extensively implicated in the progression of type 2 diabetes. Alterations of the uterine mitochondrial phenotype in pregnant women with diabetes have yet to be investigated as a causal link to decreased myometrial contractility. METHODS Observational study of 18 women with diabetes (type 2 and gestational) scheduled for an elective Caesarean section at term with matching controls. A uterine biopsy and fasting blood samples were taken on the day of delivery. RESULTS Respiration rates in isolated mitochondria and myometrial mRNA levels of genes related to mitochondrial biogenesis were unaffected by diabetes. Mitochondrial quantity examined by quantification of the complexes of the respiratory chain and histology did not indicate alterations in mitochondrial quantity. Citrate syntase activity was higher (0.31 ± 0.02 vs. 0.24 ± 0.02 U/mg protein, P = 0.008), whereas protein content was lower in women with diabetes compared with the control group (94.6 ± 6.9 vs. 118.6 ± 7.4 mg/g wet wt, P = 0.027). Histological examinations did not support any structural alterations in the myometrium or its mitochondria. CONCLUSION No indication of decreased mitochondrial function, content, morphology, or localization in the myometrium at term in women with diabetes compared with controls was observed. The increase in citrate syntase activity in the myometrium could be explained by the lower protein content in the myometrium, which we suggest is due to alterations in tissue or cellular composition.
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Affiliation(s)
- Christiane Marie Bourgin Folke Gam
- Cellular and Metabolic Research Section, Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Blegdamsvej 3, Bygning 6.5, 2200, Copenhagen N, Denmark.
- Center for Pregnant Women with Diabetes, Rigshospitalet, Copenhagen N, Denmark.
- Department of Obstetrics, Rigshospitalet, Copenhagen, Denmark.
| | - Ole Hartvig Mortensen
- Cellular and Metabolic Research Section, Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Blegdamsvej 3, Bygning 6.5, 2200, Copenhagen N, Denmark
| | - Lea Hüche Larsen
- Cellular and Metabolic Research Section, Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Blegdamsvej 3, Bygning 6.5, 2200, Copenhagen N, Denmark
| | - Steen Seier Poulsen
- Endocrinology Research Section, University of Copenhagen, Copenhagen N, Denmark
| | - Klaus Qvortrup
- Core Facility for Integrated Microscopy, Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Elisabeth Reinhart Mathiesen
- Departement of Endocrinology, Rigshospitalet, Copenhagen N, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen N, Denmark
| | - Peter Damm
- Center for Pregnant Women with Diabetes, Rigshospitalet, Copenhagen N, Denmark
- Department of Obstetrics, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen N, Denmark
| | - Bjørn Quistorff
- Cellular and Metabolic Research Section, Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Blegdamsvej 3, Bygning 6.5, 2200, Copenhagen N, Denmark
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Abstract
PURPOSE OF REVIEW The role of mitochondria in the development of skeletal muscle insulin resistance has been an area of intense investigation and debate for over 20 years. The mitochondria is a multifaceted organelle that plays an integral part in substrate metabolism and cellular signalling. This article aims to summarize the current findings and thought regarding the relationship between mitochondria and insulin resistance in skeletal muscle. RECENT FINDINGS Skeletal muscle insulin resistance was earlier thought to result from deficiency in mitochondrial oxidative capacity and ectopic lipid accumulation. Recent evidence suggests that skeletal muscle insulin resistance in high-energy intake models (i.e. obesity) results primarily from disrupted mitochondrial bioenergetics and alterations in mitochondrial-associated cell signalling. These signalling pathways include reactive oxygen species and redox balance, fatty acid β-oxidation intermediates, mitochondrial derived peptides, sirtuins, microRNAs and novel nuclear-encoded, mitochondria-acting peptides. SUMMARY The pathophysiology of skeletal muscle insulin resistance is likely multifactorial involving many coordinated physiological processes. However, it is apparent that the mitochondria play an essential role in skeletal muscle insulin sensitivity in health, ageing and in numerous metabolic diseases. Deciphering the manifold functions of the mitochondria will allow us to understand the complex relationship between mitochondria and skeletal muscle insulin resistance.
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Affiliation(s)
- William Todd Cade
- Program in Physical Therapy & Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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