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Balakrishnan R, Thurmond DC. Mechanisms by Which Skeletal Muscle Myokines Ameliorate Insulin Resistance. Int J Mol Sci 2022; 23:4636. [PMID: 35563026 PMCID: PMC9102915 DOI: 10.3390/ijms23094636] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/17/2022] [Accepted: 04/18/2022] [Indexed: 12/17/2022] Open
Abstract
The skeletal muscle is the largest organ in the body and secretes circulating factors, including myokines, which are involved in various cellular signaling processes. Skeletal muscle is vital for metabolism and physiology and plays a crucial role in insulin-mediated glucose disposal. Myokines have autocrine, paracrine, and endocrine functions, serving as critical regulators of myogenic differentiation, fiber-type switching, and maintaining muscle mass. Myokines have profound effects on energy metabolism and inflammation, contributing to the pathophysiology of type 2 diabetes (T2D) and other metabolic diseases. Myokines have been shown to increase insulin sensitivity, thereby improving glucose disposal and regulating glucose and lipid metabolism. Many myokines have now been identified, and research on myokine signaling mechanisms and functions is rapidly emerging. This review summarizes the current state of the field regarding the role of myokines in tissue cross-talk, including their molecular mechanisms, and their potential as therapeutic targets for T2D.
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Affiliation(s)
| | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope Beckman Research Institute, 1500 E. Duarte Road, Duarte, CA 91010, USA;
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Boone-Villa D, Ventura-Sobrevilla J, Aguilera-Méndez A, Jiménez-Villarreal J. The effect of adenosine monophosphate-activated protein kinase on lipolysis in adipose tissue: an historical and comprehensive review. Arch Physiol Biochem 2022; 128:7-23. [PMID: 35143739 DOI: 10.1080/13813455.2019.1661495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
CONTEXT Lipolysis is one of the most important pathways for energy management, its control in the adipose tissue (AT) is a potential therapeutic target for metabolic diseases. Adenosine Mono Phosphate-activated Protein Kinase (AMPK) is a key regulatory enzyme in lipids metabolism and a potential target for diabetes and obesity treatment. OBJECTIVE The aim of this work is to analyse the existing information on the relationship of AMPK and lipolysis in the AT. METHODS A thorough search of bibliography was performed in the databases Scopus and Web of Knowledge using the terms lipolysis, adipose tissue, and AMPK, the unrelated publications were excluded, and the documents were analysed. RESULTS Sixty-three works were found and classified in 3 categories: inhibitory effects, stimulatory effect, and diverse relationships; remarkably, the newest researches support an upregulating relationship of AMPK over lipolysis. CONCLUSION The most probable reality is that the relationship AMPK-lipolysis depends on the experimental conditions.
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Affiliation(s)
- Daniel Boone-Villa
- School of Medicine Northern Unit, Universidad Autonoma de Coahuila, Piedras Negras, México
| | | | - Asdrúbal Aguilera-Méndez
- Institute of Biological Chemistry Research, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, México
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Braun JL, Ryoo J, Goodwin K, Copeland EN, Geromella MS, Baranowski RW, MacPherson REK, Fajardo VA. The effects of neurogranin knockdown on SERCA pump efficiency in soleus muscles of female mice fed a high fat diet. Front Endocrinol (Lausanne) 2022; 13:957182. [PMID: 36072929 PMCID: PMC9441848 DOI: 10.3389/fendo.2022.957182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/05/2022] [Indexed: 11/26/2022] Open
Abstract
The sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) pump is responsible for the transport of Ca2+ from the cytosol into the sarcoplasmic reticulum at the expense of ATP, making it a regulator of both muscle relaxation and muscle-based energy expenditure. Neurogranin (Ng) is a small protein that negatively regulates calcineurin signaling. Calcineurin is Ca2+/calmodulin dependent phosphatase that promotes the oxidative fibre type in skeletal muscle and regulates muscle-based energy expenditure. A recent study has shown that calcineurin activation reduces SERCA Ca2+ transport efficiency, ultimately raising energy expenditure. Since the biomedical view of obesity states that it arises as an imbalance between energy intake and expenditure which favors the former, we questioned whether heterozygous Ng deletion (Ng+/- ) would reduce SERCA efficiency and increase energy expenditure in female mice fed a high-fat diet (HFD). Young (3-4-month-old) female wild type (WT) and Ng+/- mice were fed a HFD for 12 weeks with their metabolic profile being analyzed using metabolic cages and DXA scanning, while soleus SERCA efficiency was measured using SERCA specific Ca2+ uptake and ATPase activity assays. Ng+/- mice showed significantly less cage ambulation compared to WT mice but this did not lead to any added weight gain nor changes in daily energy expenditure, glucose or insulin tolerance despite a similar level of food intake. Furthermore, we observed significant reductions in SERCA's apparent coupling ratio which were associated with significant reductions in SERCA1 and phospholamban content. Thus, our results show that Ng regulates SERCA pump efficiency, and future studies should further investigate the potential cellular mechanisms.
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Affiliation(s)
- Jessica L. Braun
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Jisook Ryoo
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Kyle Goodwin
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Emily N. Copeland
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Mia S. Geromella
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Ryan W. Baranowski
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Rebecca E. K. MacPherson
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Val A. Fajardo
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
- *Correspondence: Val A. Fajardo,
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Minafra AR, Chadt A, Rafii P, Al-Hasani H, Behnke K, Scheller J. Interleukin 6 receptor is not directly involved in regulation of body weight in diet-induced obesity with and without physical exercise. Front Endocrinol (Lausanne) 2022; 13:1028808. [PMID: 36387898 PMCID: PMC9647089 DOI: 10.3389/fendo.2022.1028808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/04/2022] [Indexed: 12/01/2022] Open
Abstract
High level of interleukin 6 (IL-6), released by adipocytes in an obesity-induced, low grade inflammation state, is a regulator of insulin resistance and glucose tolerance. IL-6 has also regenerative, anti-inflammatory and anti-diabetogenic functions, when secreted as myokine by skeletal muscles during physical exercise. IL-6 mainly activates cells via two different receptor constellations: classic and trans-signalling, in which IL-6 initially binds to membrane-bound receptor (IL-6R) or soluble IL-6 receptor (sIL-6R) before activating signal transducing gp130 receptor. Previously, we generated transgenic soluble IL-6 receptor +/+ (sIL-6R+/+) mice with a strategy that mimics ADAM10/17 hyperactivation, reflecting a situation in which only IL-6 trans-signalling is active, whereas classic signalling is completely abrogated. In this study, we metabolically phenotyped IL-6R deficient mice (IL-6R-KO), sIL-6R+/+ mice and wild-type littermates fed either a standard chow (SD) or a high-fat diet (HFD) in combination with a 6-weeks treadmill exercise protocol. All mice were subjected to analyses of body weight and body composition, determination of blood glucose and insulin level under fasting conditions, as well as determination of substrate preference by indirect calorimetry. Neither classic IL-6 nor trans-signalling do influence the outcome of diet-induced obesity, insulin sensitivity and glycaemic control. Furthermore, IL-6R deficiency is not impairing the beneficial effect of physical exercise. We conclude that the IL-6R does not play a requisite role in regulation of body weight and glucose metabolism in diet-induced obese mice.
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Affiliation(s)
- Anna Rita Minafra
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Alexandra Chadt
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
- German Center for Diabetes Research Deutsches Zentrum für Diabetesforschung e.V. (DZD), Partner Düsseldorf, München, Neuherberg, Germany
| | - Puyan Rafii
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Hadi Al-Hasani
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
- German Center for Diabetes Research Deutsches Zentrum für Diabetesforschung e.V. (DZD), Partner Düsseldorf, München, Neuherberg, Germany
| | - Kristina Behnke
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Jürgen Scheller
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
- *Correspondence: Jürgen Scheller,
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Blocking endogenous IL-6 impairs mobilization of free fatty acids during rest and exercise in lean and obese men. CELL REPORTS MEDICINE 2021; 2:100396. [PMID: 34622233 PMCID: PMC8484687 DOI: 10.1016/j.xcrm.2021.100396] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 06/03/2021] [Accepted: 08/17/2021] [Indexed: 12/26/2022]
Abstract
Lack of interleukin-6 (IL-6) leads to expansion of adipose tissue mass in rodents and humans. The exact underlying mechanisms have not been identified. In this placebo-controlled, non-randomized, participant-blinded crossover study, we use the IL-6 receptor antibody tocilizumab to investigate the role of endogenous IL-6 in regulating systemic energy metabolism at rest and during exercise and recovery in lean and obese men using tracer dilution methodology. Tocilizumab reduces fatty acid appearance in the circulation under all conditions in lean and obese individuals, whereas lipolysis (the rate of glycerol appearance into the circulation) is mostly unaffected. The fact that fatty acid oxidation is unaffected by IL-6 receptor blockade suggests increased re-esterification of fatty acids. Glucose kinetics are unaffected. We find that blocking endogenous IL-6 signaling with tocilizumab impairs fat mobilization, which may contribute to expansion of adipose tissue mass and, thus, affect the health of individuals undergoing anti-IL-6 therapy (Clinicaltrials.gov: NCT03967691).
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Biochemical adaptations in white adipose tissue following aerobic exercise: from mitochondrial biogenesis to browning. Biochem J 2020; 477:1061-1081. [PMID: 32187350 DOI: 10.1042/bcj20190466] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/24/2020] [Accepted: 02/28/2020] [Indexed: 02/07/2023]
Abstract
Our understanding of white adipose tissue (WAT) biochemistry has evolved over the last few decades and it is now clear that WAT is not simply a site of energy storage, but rather a pliable endocrine organ demonstrating dynamic responsiveness to the effects of aerobic exercise. Similar to its established effects in skeletal muscle, aerobic exercise induces many biochemical adaptations in WAT including mitochondrial biogenesis and browning. While past research has focused on the regulation of these biochemical processes, there has been renewed interest as of late given the potential of harnessing WAT mitochondrial biogenesis and browning to treat obesity and type II diabetes. Unfortunately, despite increasing evidence that innumerable factors, both exercise induced and pharmacological, can elicit these biochemical adaptations in WAT, the underlying mechanisms remain poorly defined. Here, we begin with a historical account of our understanding of WAT exercise biochemistry before presenting detailed evidence in favour of an up-to-date model by which aerobic exercise induces mitochondrial biogenesis and browning in WAT. Specifically, we discuss how aerobic exercise induces increases in WAT lipolysis and re-esterification and how this could be a trigger that activates the cellular energy sensor 5' AMP-activated protein kinase to mediate the induction of mitochondrial biogenesis and browning via the transcriptional co-activator peroxisome proliferator-activated receptor gamma co-activator-1 alpha. While this review primarily focuses on mechanistic results from rodent studies special attention is given to the translation of these results, or lack thereof, to human physiology.
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Impact of skeletal muscle IL-6 on subcutaneous and visceral adipose tissue metabolism immediately after high- and moderate-intensity exercises. Pflugers Arch 2019; 472:217-233. [PMID: 31781893 DOI: 10.1007/s00424-019-02332-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/23/2019] [Accepted: 11/13/2019] [Indexed: 12/28/2022]
Abstract
White adipose tissue is a major energy reserve for the body and is essential for providing fatty acids for other tissues when needed. Skeletal muscle interleukin-6 (IL-6) has been shown to be secreted from the working muscle and has been suggested to signal to adipose tissue and enhance lipolysis. The aim of the present study was to investigate the role of skeletal muscle IL-6 in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) lipolysis and glyceroneogenesis with prolonged moderate-intensity exercise and high-intensity exercise in mice. Female inducible muscle-specific IL-6 knockout (IL-6 iMKO) mice and littermate control (Floxed) mice performed a single exercise bout for either 120 min at 16 m/min and 10° slope (moderate intensity) or 30 min at 20 m/min and 10° slope (high intensity), or they remained rested (rest). Visceral and subcutaneous adipose tissues, quadriceps muscles, and blood were quickly obtained. Plasma IL-6 increased in Floxed mice but not in IL-6 iMKO mice with high-intensity exercise. VAT signal transducer and activator of transcription (STAT)3Tyr705 phosphorylation was lower, and VAT hormone-sensitive lipase (HSL)Ser563 phosphorylation was higher in IL-6 iMKO mice than in Floxed mice at rest. Furthermore, HSLSer563 and HSLSer660 phosphorylation increased in VAT and phosphoenolpyruvate carboxykinase protein decreased in SAT with moderate-intensity exercise in both genotypes. On the other hand, both exercise protocols increased pyruvate dehydrogenaseSer232 phosphorylation in VAT only in IL-6 iMKO mice and decreased tumor necrosis factor-α messenger RNA in SAT and VAT only in Floxed mice. In conclusion, the present findings suggest that skeletal muscle IL-6 regulates markers of lipolysis in VAT in the basal state and pyruvate availability for glyceroneogenesis in VAT with exercise. Moreover, skeletal muscle IL-6 may contribute to exercise-induced anti-inflammatory effects in SAT and VAT.
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Townsend LK, Wright DC. Looking on the "brite" side exercise-induced browning of white adipose tissue. Pflugers Arch 2019; 471:455-465. [PMID: 29982948 DOI: 10.1007/s00424-018-2177-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/26/2018] [Accepted: 06/27/2018] [Indexed: 12/17/2022]
Abstract
The need for effective and convenient ways of combatting obesity has created great interest in brown adipose tissue (BAT). However, because adult humans have relatively little amounts of BAT, the possibility of browning white adipose tissue (WAT), i.e., switching the metabolism of WAT from an energy storing to energy burning organ, has gained considerable attention. Exercise has countless health benefits, and has consistently been shown to cause browning in rodent white adipose tissue. The purpose of this review is to provide an overview of recent studies examining the effects of exercise and other interventions on the browning of white adipose tissue. The role of various endocrine factors, including catecholamines, interleukin-6, irisin, and meteorin-like in addition to local re-esterification-mediated mechanisms in inducing the browning of WAT will be discussed. The physiological importance of browning will be discussed, as will discrepancies in the literature between human and rodent studies.
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Affiliation(s)
- Logan K Townsend
- Department of Human Health and Nutritional Science, University of Guelph, 50 Stone Rd E, Guelph, Ontario, N1G 2W1, Canada
| | - David C Wright
- Department of Human Health and Nutritional Science, University of Guelph, 50 Stone Rd E, Guelph, Ontario, N1G 2W1, Canada.
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Knudsen JG, Gudiksen A, Bertholdt L, Overby P, Villesen I, Schwartz CL, Pilegaard H. Skeletal muscle IL-6 regulates muscle substrate utilization and adipose tissue metabolism during recovery from an acute bout of exercise. PLoS One 2017; 12:e0189301. [PMID: 29253016 PMCID: PMC5734691 DOI: 10.1371/journal.pone.0189301] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/23/2017] [Indexed: 12/13/2022] Open
Abstract
An acute bout of exercise imposes a major challenge on whole-body metabolism and metabolic adjustments are needed in multiple tissues during recovery to reestablish metabolic homeostasis. It is currently unresolved how this regulation is orchestrated between tissues. This study was undertaken to clarify the role of skeletal muscle derived interleukin 6 (IL-6) in the coordination of the metabolic responses during recovery from acute exercise. Skeletal muscle specific IL-6 knockout (IL-6 MKO) and littermate Control mice were rested or ran on a treadmill for 2h. Plasma, skeletal muscle, liver and adipose tissue were obtained after 6 and 10h of recovery. Non-exercised IL-6 MKO mice had higher plasma lactate and lower plasma non-esterified fatty acids than Controls. The activity of pyruvate dehydrogenase in the active form was, in skeletal muscle, higher in IL-6 MKO mice than Controls in non-exercised mice and 6h after exercise. IL-6 MKO mice had lower glucose transporter 4 protein content in inguinal adipose tissue (WAT) than Control in non-exercised mice and 10h after treadmill running. Epididymal WAT hormone sensitive lipase phosphorylation and inguinal WAT mitogen activated kinase P38 phosphorylation were higher in IL-6 MKO than Control mice 6h after exercise. These findings indicate that skeletal muscle IL-6 may play an important role in the regulation of substrate utilization in skeletal muscle, basal and exercise-induced adaptations in adipose tissue glucose uptake and lipolysis during recovery from exercise. Together this indicates that skeletal muscle IL-6 contributes to reestablishing metabolic homeostasis during recovery from exercise by regulating WAT and skeletal muscle metabolism.
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Affiliation(s)
- Jakob G. Knudsen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (JGK); (HP)
| | - Anders Gudiksen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lærke Bertholdt
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Peter Overby
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ida Villesen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Camilla L. Schwartz
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (JGK); (HP)
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Townsend LK, Knuth CM, Wright DC. Cycling our way to fit fat. Physiol Rep 2017; 5:5/7/e13247. [PMID: 28404813 PMCID: PMC5392531 DOI: 10.14814/phy2.13247] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 03/10/2017] [Accepted: 03/16/2017] [Indexed: 12/25/2022] Open
Abstract
Adipose tissue is increasingly being recognized as a key regulator of whole body carbohydrate and lipid metabolism. In conditions of obesity and insulin resistance mitochondrial content in this tissue is reduced, while treatment with insulin sensitizing drugs such as thiazolidinediones (TZDs) increase mitochondrial content. It has been known for decades that exercise increases mitochondrial content in skeletal muscle and now several laboratories have shown similar effects in adipose tissue. To date the specific mechanisms mediating this effect have not been fully identified. In this review we highlight recent work suggesting that increases in lipolysis and subsequently fatty acid re‐esterification trigger the activation of 5' AMP‐activated protein kinase (AMP) activated protein kinase and ultimately the induction of mitochondrial biogenesis. It is our current view that this pathway could be a unifying mechanism linking numerous systemic factors (catecholamines, interleukin‐6, meteorin‐like) to induction of mitochondrial biogenesis following exercise.
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Affiliation(s)
- Logan K Townsend
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Canada
| | - Carly M Knuth
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Canada
| | - David C Wright
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Canada
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MacDonald TL, MacPherson R, Castellani L, Cervone D, Anderson E, Wright DC, Dyck DJ. Estradiol does not directly regulate adipose lipolysis. Adipocyte 2017; 6:76-86. [PMID: 28425842 DOI: 10.1080/21623945.2017.1287638] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The mechanisms by which estradiol modulates adipose lipolysis are poorly understood. We sought to measure basal and β3-stimulated indices of lipoysis (FFAs, glycerol) in vivo in E2 deficient or supplemented rats, and ex vivo with direct acute E2 exposure. For 2 weeks, ovariectomized (OVX) and OVX rats treated with a daily oral dose of E2 (OVX E2) were pairfed to SHAM controls (n = 12 per group). Adipocyte size was modestly (∼40%) increased in OVX rats, but did not reach significance (p = 0.2). After 2 weeks, half of the animals in each group received an in vivo injection of saline or 1 mg/kg of the β3 agonist CL 316, 243. Serum FFA concentrations, but not glycerol, were lower in OVX and OVX E2 rats compared with SHAM controls (p = 0.02). A significant CL response was present in all groups (p<0.001) and HSL activation was unaffected by OVX or OVX E2 in retroperitoneal (r.p.) or inguinal (iWAT) adipose depots in vivo. Ex vivo, CL increased FFA and glycerol accumulation in the media as well as HSL phosphorylation by several fold in r.p. and iWAT explants, but responses from OVX and OVX E2 rats were comparable to SHAMs. To assess whether E2 can directly affect lipolysis, r.p. and iWAT tissue was treated with E2, CL or E2 + CL for 2, 4 or 8 hours using adipose tissue organ culture. CL stimulated FFA release (p<0.001), but was unaffected by E2. Overall, our results indicate that E2 does not directly regulate adipose tissue lipolysis.
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Affiliation(s)
- Tara L. MacDonald
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Rebecca MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Daniel Cervone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Eoin Anderson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C. Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David J. Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Nieman DC, Sha W, Pappan KL. IL-6 Linkage to Exercise-Induced Shifts in Lipid-Related Metabolites: A Metabolomics-Based Analysis. J Proteome Res 2017; 16:970-977. [PMID: 27996272 DOI: 10.1021/acs.jproteome.6b00892] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Metabolomics profiling and bioinformatics technologies were used to determine the relationship between exercise-induced increases in IL-6 and lipid-related metabolites. Twenty-four male runners (age 36.5 ± 1.8 y) ran on treadmills to exhaustion (2.26 ± 0.01 h, 24.9 ± 1.3 km, 69.7 ± 1.9% VO2max). Vastus lateralis muscle biopsy and blood samples were collected before and immediately after running and showed a 33.7 ± 4.2% decrease in muscle glycogen, 39.0 ± 8.8-, 2.4 ± 0.3-, and 1.4 ± 0.1-fold increases in plasma IL-6, IL-8, and MCP-1, respectively, and 95.0 ± 18.9 and 158 ± 20.6% increases in cortisol and epinephrine, respectively (all, P < 0.001). The metabolomics analysis revealed changes in 209 metabolites, especially long- and medium-chain fatty acids, fatty acid oxidation products (dicarboxylate and monohydroxy fatty acids, acylcarnitines), and ketone bodies. OPLS-DA modeling supported a strong separation in pre- and post-exercise samples (R2Y = 0.964, Q2Y = 0.902). OPLSR analysis failed to produce a viable model for the relationship between IL-6 and all lipid-related metabolites (R2Y = 0.76, Q2Y = -0.0748). Multiple structure equation models were evaluated based on IL-6, with the best-fit pathway model showing a linkage of exercise time to IL-6, then carnitine, and 13-methylmyristic acid (a marker for adipose tissue lipolysis) and sebacate. These metabolomics-based data indicate that the increase in plasma IL-6 after long endurance running has a minor relationship to increases in lipid-related metabolites.
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Affiliation(s)
- David C Nieman
- Human Performance Laboratory, Appalachian State University , North Carolina Research Campus, Kannapolis, North Carolina 28081, United States
| | - Wei Sha
- Bioinformatics Services Division, University of North Carolina at Charlotte , North Carolina Research Campus, Kannapolis, North Carolina 28081, United States
| | - Kirk L Pappan
- Metabolon, Inc. , Durham, North Carolina 27713, United States
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Patin F, Baranek T, Vourc'h P, Nadal-Desbarats L, Goossens JF, Marouillat S, Dessein AF, Descat A, Hounoum BM, Bruno C, Watier H, Si-Tahar M, Leman S, Lecron JC, Andres CR, Corcia P, Blasco H. Combined Metabolomics and Transcriptomics Approaches to Assess the IL-6 Blockade as a Therapeutic of ALS: Deleterious Alteration of Lipid Metabolism. Neurotherapeutics 2016; 13:905-917. [PMID: 27444617 PMCID: PMC5081117 DOI: 10.1007/s13311-016-0461-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In amyotrophic lateral sclerosis (ALS), motor neuron degeneration occurs simultaneously with systemic metabolic impairment and neuroinflammation. Playing an important role in the regulation of both phenomena, interleukin (IL)-6, a major cytokine of the inflammatory response has been proposed as a target for management of ALS. Although a pilot clinical trial provided promising results in humans, another recent preclinical study showed that knocking out the IL-6 gene in mice carrying ALS did not improve clinical outcome. In this study, we aimed to determine the relevance of the IL-6 pathway blockade in a mouse model of ALS by using a pharmacological antagonist of IL-6, a murine surrogate of tocilizumab, namely MR16-1. We analyzed the immunological and metabolic effects of IL-6 blockade by cytokine measurement, blood cell immunophenotyping, targeted metabolomics, and transcriptomics. A deleterious clinical effect of MR16-1 was revealed, with a speeding up of weight loss (p = 0.0041) and decreasing body weight (p < 0.05). A significant increase in regulatory T-cell count (p = 0.0268) and a decrease in C-X-C ligand-1 concentrations in plasma (p = 0.0479) were observed. Metabolomic and transcriptomic analyses revealed that MR16-1 mainly affected branched-chain amino acid, lipid, arginine, and proline metabolism. IL-6 blockade negatively affected body weight, despite a moderated anti-inflammatory effect. Metabolic effects of IL-6 were mild compared with metabolic disturbances observed in ALS, but a modification of lipid metabolism by therapy was identified. These results indicate that IL-6 blockade did not improve clinical outcome of a mutant superoxide dismutase 1 mouse model of ALS.
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Affiliation(s)
- Franck Patin
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France.
- CHRU de Tours, Laboratoire de Biochimie et de Biologie Moléculaire, Tours, France.
| | - Thomas Baranek
- INSERM, UMR 1100 "Centre d'étude des Pathologies Respiratoires, Université François Rabelais, Tours, France
| | - Patrick Vourc'h
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
- CHRU de Tours, Laboratoire de Biochimie et de Biologie Moléculaire, Tours, France
- PPF "Analyse des systèmes biologiques", Université François Rabelais de Tours, Tours, France
| | - Lydie Nadal-Desbarats
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
- PPF "Analyse des systèmes biologiques", Université François Rabelais de Tours, Tours, France
| | - Jean-François Goossens
- Centre Universitaire de Mesures et d'Analyses (CUMA), Université de Lille 2, Lille, France
| | - Sylviane Marouillat
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
| | | | - Amandine Descat
- Centre Universitaire de Mesures et d'Analyses (CUMA), Université de Lille 2, Lille, France
| | | | - Clément Bruno
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
- CHRU de Tours, Laboratoire de Biochimie et de Biologie Moléculaire, Tours, France
| | - Hervé Watier
- CHRU de Tours, Laboratoire d'Immunologie, Tours, France
| | - Mustafa Si-Tahar
- INSERM, UMR 1100 "Centre d'étude des Pathologies Respiratoires, Université François Rabelais, Tours, France
| | - Samuel Leman
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
| | - Jean-Claude Lecron
- CHU de Poitiers, Laboratoire d'Immunologie, Poitiers, France
- Laboratoire Inflammation, Tissus Epithéliaux et Cytokines, UPRES EA4331, Pôle Biologie Santé, Université de Poitiers, Poitiers, France
| | - Christian R Andres
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
- CHRU de Tours, Laboratoire de Biochimie et de Biologie Moléculaire, Tours, France
| | - Philippe Corcia
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
- CHRU de Tours, Fédération des CRCSLA Tours-Limoges (LITORALS), Tours, France
| | - Hélène Blasco
- INSERM, UMR U930 "Imagerie et Cerveau", Université François Rabelais, Tours, France
- CHRU de Tours, Laboratoire de Biochimie et de Biologie Moléculaire, Tours, France
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Effects of 8-Week Hatha Yoga Training on Metabolic and Inflammatory Markers in Healthy, Female Chinese Subjects: A Randomized Clinical Trial. BIOMED RESEARCH INTERNATIONAL 2016; 2016:5387258. [PMID: 27563670 PMCID: PMC4987461 DOI: 10.1155/2016/5387258] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 06/30/2016] [Indexed: 11/17/2022]
Abstract
We aimed to determine the effects of an 8 wk Hatha yoga training on blood glucose, insulin, lipid profiles, endothelial microparticles (EMPs), and inflammatory status in healthy, lean, and female Chinese subjects. A total of 30 healthy, female Chinese subjects were recruited and randomized into control or yoga practice group. The yoga practice included 8 wks of yoga practice (2 times/wk) for a total of 16 times. Fasting blood samples were collected before and after yoga training. Plasma was isolated for the measurement of lipid profiles, glucose, insulin, EMPs, and inflammatory cytokines. Whole blood was cultured ex vivo and stimulated with lipopolysaccharide (LPS) and Pam3Cys-SK4. Peripheral blood mononuclear cells (PBMCs) were isolated for the measurement of TLR2 and TLR4 protein expression. Yoga practice significantly reduced plasma cholesterol, LDL-cholesterol, insulin levels, and CD31+/CD42b- EMPs. Cultured whole blood from the yoga group has reduced proinflammatory cytokines secretion both at unstimulated condition and when stimulated with Pam3Cys-SK4; this might be associated with reduced TLR2 protein expression in PBMCs after yoga training. Hatha yoga practice in healthy Chinese female subjects could improve hallmarks related to MetS; thus it can be considered as an ancillary intervention in the primary MetS prevention for the healthy population. This trial is registered with ChiCTR-IOR-14005747.
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15
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Lei T, Yu L, Qin L, Xu B, Zhou L, Cheng J, Zhou H, Pang X, Wan Z. Stress kinases, endoplasmic reticulum stress, and Alzheimer's disease related markers in peripheral blood mononuclear cells from subjects with increased body weight. Sci Rep 2016; 6:30890. [PMID: 27481183 PMCID: PMC4969589 DOI: 10.1038/srep30890] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 07/12/2016] [Indexed: 12/13/2022] Open
Abstract
We aimed to characterize endoplasmic reticulum stress, inflammation, and Alzheimer’s disease (AD) related markers in peripheral blood mononuclear cells (PBMCs) from males with varied BMI; and to explore whether high glucose and fatty acids (FFAs) might be critical factors for inducing metabolic alterations in PBMCs under obese condition. Approximately 45 middle-aged men were enrolled with varied BMI. At the protein expression level, compared to the lean, the phosphorylation of AMPK, and p-Akt at serine 473 were significantly reduced from the overweight (OW) and/or obese (OB); while the protein expression of p-JNK, cleaved caspase 3, CHOP and p-eIF2α were elevated from the OW and/or OB. At the mRNA expression level, ER stress markers (i.e. GRP78, CHOP and XBP-1), inflammatory markers (i.e.TLR2, TLR4 and CCR2) and AD markers (i.e. APP, PS1 and PS2) were significantly higher in PBMCs from OB compared to lean. In cultured PBMCs, high glucose and FFAs induced GRP78, CHOP and XBP-1 mRNA, and high glucose also induced APP, PS1 and PS2 mRNA. In conclusion, altered markers including AMPK, ER stress and AD related makers under obese condition could be easily obtained from PBMCs. These markers might provide new mechanistic links between obesity and other metabolic complications including AD.
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Affiliation(s)
- Ting Lei
- Suzhou Industrial Park center Disease Control &Prevention, 58 Suqian Road, Suzhou, 215123, P.R. China
| | - Lugang Yu
- Suzhou Industrial Park center Disease Control &Prevention, 58 Suqian Road, Suzhou, 215123, P.R. China
| | - Liqiang Qin
- Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, 199 Renai Road, Suzhou, 215123, P.R. China
| | - Baohui Xu
- Suzhou Industrial Park center Disease Control &Prevention, 58 Suqian Road, Suzhou, 215123, P.R. China
| | - Lingmei Zhou
- Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, 199 Renai Road, Suzhou, 215123, P.R. China
| | - Jinbo Cheng
- Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, 199 Renai Road, Suzhou, 215123, P.R. China
| | - Hui Zhou
- Suzhou Industrial Park center Disease Control &Prevention, 58 Suqian Road, Suzhou, 215123, P.R. China
| | - Xing Pang
- Suzhou Industrial Park center Disease Control &Prevention, 58 Suqian Road, Suzhou, 215123, P.R. China
| | - Zhongxiao Wan
- Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, 199 Renai Road, Suzhou, 215123, P.R. China.,Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Disease, Soochow University, 199 Renai Road, Suzhou, 215123, P.R. China
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16
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Macpherson REK, Huber JS, Frendo-Cumbo S, Simpson JA, Wright DC. Adipose Tissue Insulin Action and IL-6 Signaling after Exercise in Obese Mice. Med Sci Sports Exerc 2016; 47:2034-42. [PMID: 25785928 DOI: 10.1249/mss.0000000000000660] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Adipose tissue insulin action is impaired in obesity and is associated with inflammation, macrophage infiltration, and polarization toward a proinflammatory phenotype. Acute exercise can reduce markers of adipose inflammation, including interleukin (IL) 6, in parallel with improvements in insulin action; however, others have provided evidence that IL-6 has anti-inflammatory properties. PURPOSE This study aimed to examine the relation between IL-6 signaling, macrophage infiltration, and polarization and insulin action in inguinal fat after acute exercise in obese, insulin-resistant mice. METHODS Male C57BL/6 mice were fed a low-fat diet (10% kcal lard) or a high-fat diet (HFD, 60% kcal lard) for 7 wk and then underwent an acute bout of exercise (2-h treadmill running: 15 m·min, 5% incline). RESULTS The HFD resulted in increased body mass, glucose intolerance, and attenuated insulin-induced AKT Thr308 phosphorylation in inguinal fat. This was accompanied by increases in indices of macrophage infiltration (F4/80, CD68, and monocyte chemoattractant protein-1 expression) and polarization toward an M1 phenotype (increased expression of CD11c, CD11c/galactose-type C-type lectin 1, and inducible nitric oxide synthase). Immunofluorescence imaging demonstrated increased F4/80- and CD11c-positive cells with the HFD. Two hours after exercise, the insulin-induced activation of AKT Th308 phosphorylation was recovered in HFD mice. This was accompanied by an upregulation of IL-6 and IL-10 signaling, as demonstrated by increased expression of IL-6, IL-10, and SOCS3 as well as STAT3 phosphorylation. Furthermore, acute exercise resulted in a shift toward reduction in M1 polarization indicated by a decrease in the ratio of CD11c to galactose-type C-type lectin 1 mRNA as well as a decline in F4/80- and CD11c-positive cells. CONCLUSIONS The results suggest a link between exercise-induced increases in IL-6, reductions in indices of M1 macrophages, and increased IL-10, a reputed anti-inflammatory cytokine with insulin-sensitizing properties.
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Affiliation(s)
- Rebecca E K Macpherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
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17
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Castellani L, Perry CGR, Macpherson REK, Root-McCaig J, Huber JS, Arkell AM, Simpson JA, Wright DC. Exercise-mediated IL-6 signaling occurs independent of inflammation and is amplified by training in mouse adipose tissue. J Appl Physiol (1985) 2015; 119:1347-54. [PMID: 26472868 DOI: 10.1152/japplphysiol.00551.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/05/2015] [Indexed: 01/24/2023] Open
Abstract
The purpose of this investigation was to determine whether exercise-induced increases in adipose tissue interleukin 6 (IL-6) signaling occurred as part of a larger proinflammatory response to exercise and whether the induction of IL-6 signaling with acute exercise was altered in trained mice in parallel with changes in the IL-6 receptor complex. Sedentary and trained C57BL/6J mice were challenged with an acute bout of exercise. Adipose tissue and plasma were collected immediately and 4 h afterward and analyzed for changes in indices of IL-6 signaling, circulating IL-6, markers of adipose tissue inflammation, and expression/content of IL-6 receptor and glycoprotein 130 (gp130). In untrained mice, IL-6 mRNA increased immediately after exercise, and increases in indices of IL-6 signaling were increased 4 h after exercise in epididymal, but not inguinal adipose tissue. This occurred independent of increases in plasma IL-6 and alterations in markers of inflammation. When compared with untrained mice, in trained mice, acute exercise induced the expression of gp130 and IL-6 receptor alpha (IL-6Rα), and training increased the protein content of these. Acute exercise induced the expression, and training increased the protein content, of glycoprotein 130 and IL-6Rα and was associated with a more rapid increase in markers of IL-6 signaling in epididymal adipose tissue from trained compared with untrained mice. The ability of exogenous IL-6 to increase phosphorylation of STAT3 was similar between groups. Our findings demonstrate that acute exercise increases IL-6 signaling in a depot-dependent manner, likely through an autocrine/paracrine mechanism. This response is initiated more rapidly after exercise in trained mice, potentially as a result of increases in IL-6Rα and gp130.
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Affiliation(s)
- Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Christopher G R Perry
- Faculty of Health, School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Rebecca E K Macpherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Jared Root-McCaig
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Jason S Huber
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Alicia M Arkell
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
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18
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Bonen A, Jain SS, Snook LA, Han XX, Yoshida Y, Buddo KH, Lally JS, Pask ED, Paglialunga S, Beaudoin MS, Glatz JFC, Luiken JJFP, Harasim E, Wright DC, Chabowski A, Holloway GP. Extremely rapid increase in fatty acid transport and intramyocellular lipid accumulation but markedly delayed insulin resistance after high fat feeding in rats. Diabetologia 2015. [PMID: 26197708 DOI: 10.1007/s00125-015-3691-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS The mechanisms for diet-induced intramyocellular lipid accumulation and its association with insulin resistance remain contentious. In a detailed time-course study in rats, we examined whether a high-fat diet increased intramyocellular lipid accumulation via alterations in fatty acid translocase (FAT/CD36)-mediated fatty acid transport, selected enzymes and/or fatty acid oxidation, and whether intramyocellular lipid accretion coincided with the onset of insulin resistance. METHODS We measured, daily (on days 1-7) and/or weekly (for 6 weeks), the diet-induced changes in circulating substrates, insulin, sarcolemmal substrate transporters and transport, selected enzymes, intramyocellular lipids, mitochondrial fatty acid oxidation and basal and insulin-stimulated sarcolemmal GLUT4 and glucose transport. We also examined whether upregulating fatty acid oxidation improved glucose transport in insulin-resistant muscles. Finally, in Cd36-knockout mice, we examined the role of FAT/CD36 in intramyocellular lipid accumulation, insulin sensitivity and diet-induced glucose intolerance. RESULTS Within 2-3 days, diet-induced increases occurred in insulin, sarcolemmal FAT/CD36 (but not fatty acid binding protein [FABPpm] or fatty acid transporter [FATP]1 or 4), fatty acid transport and intramyocellular triacylglycerol, diacylglycerol and ceramide, independent of enzymatic changes or muscle fatty acid oxidation. Diet-induced increases in mitochondria and mitochondrial fatty acid oxidation and impairments in insulin-stimulated glucose transport and GLUT4 translocation occurred much later (≥21 days). FAT/CD36 ablation impaired insulin-stimulated fatty acid transport and lipid accumulation, improved insulin sensitivity and prevented diet-induced glucose intolerance. Increasing fatty acid oxidation in insulin-resistant muscles improved glucose transport. CONCLUSIONS/INTERPRETATIONS High-fat feeding rapidly increases intramyocellular lipids (in 2-3 days) via insulin-mediated upregulation of sarcolemmal FAT/CD36 and fatty acid transport. The 16-19 day delay in the onset of insulin resistance suggests that additional mechanisms besides intramyocellular lipids contribute to this pathology.
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Affiliation(s)
- Arend Bonen
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1.
| | - Swati S Jain
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Laelie A Snook
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Xiao-Xia Han
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Yuko Yoshida
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Kathryn H Buddo
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - James S Lally
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Elizabeth D Pask
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Sabina Paglialunga
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Marie-Soleil Beaudoin
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Jan F C Glatz
- Department of Molecular Genetics, Maastricht University, Maastricht, the Netherlands
| | - Joost J F P Luiken
- Department of Molecular Genetics, Maastricht University, Maastricht, the Netherlands
| | - Ewa Harasim
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - David C Wright
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Graham P Holloway
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, ON, Canada, N1G 2W1
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MacPherson REK, Baumeister P, Peppler WT, Wright DC, Little JP. Reduced cortical BACE1 content with one bout of exercise is accompanied by declines in AMPK, Akt, and MAPK signaling in obese, glucose-intolerant mice. J Appl Physiol (1985) 2015; 119:1097-104. [PMID: 26404616 DOI: 10.1152/japplphysiol.00299.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/17/2015] [Indexed: 12/15/2022] Open
Abstract
Obesity and type 2 diabetes are significant risk factors in the development of neurodegenerative diseases, such as Alzheimer's disease. A variety of cellular mechanisms, such as altered Akt and AMPK and increased inflammatory signaling, contribute to neurodegeneration. Exercise training can improve markers of neurodegeneration, but the underlying mechanisms remain unknown. The purpose of this study was to determine the effects of a single bout of exercise on markers of neurodegeneration and inflammation in brains from mice fed a high-fat diet. Male C57BL/6 mice were fed a low (LFD; 10% kcal from lard)- or a high-fat diet (HFD; 60% kcal from lard) for 7 wk. HFD mice underwent an acute bout of exercise (treadmill running: 15 m/min, 5% incline, 120 min) followed by a recovery period of 2 h. The HFD increased body mass and glucose intolerance (both P < 0.05). This was accompanied by an approximately twofold increase in the phosphorylation of Akt, ERK, and GSK in the cortex (P < 0.05). Following exercise, there was a decrease in beta-site amyloid precursor protein cleaving enzyme 1 (BACE1; P < 0.05) and activity (P < 0.001). This was accompanied by a reduction in AMPK phosphorylation, indicative of a decline in cellular stress (P < 0.05). Akt and ERK phosphorylation were decreased following exercise in HFD mice to a level similar to that of the LFD mice (P < 0.05). This study demonstrates that a single bout of exercise can reduce BACE1 content and activity independent of changes in adiposity. This effect is associated with reductions in Akt, ERK, and AMPK signaling in the cortex.
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Affiliation(s)
- R E K MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - P Baumeister
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | | | - D C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - J P Little
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Knudsen JG, Bertholdt L, Joensen E, Lassen SB, Hidalgo J, Pilegaard H. Skeletal muscle interleukin-6 regulates metabolic factors in iWAT during HFD and exercise training. Obesity (Silver Spring) 2015; 23:1616-24. [PMID: 26109166 PMCID: PMC6084358 DOI: 10.1002/oby.21139] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/01/2015] [Accepted: 04/05/2015] [Indexed: 12/23/2022]
Abstract
OBJECTIVE To investigate the role of skeletal muscle (SkM) interleukin (IL)-6 in the regulation of adipose tissue metabolism. METHODS Muscle-specific IL-6 knockout (IL-6 MKO) and IL-6(loxP/loxP) (Floxed) mice were subjected to standard rodent diet (Chow), high-fat diet (HFD), or HFD in combination with exercise training (HFD ExTr) for 16 weeks. RESULTS Total fat mass increased (P < 0.05) in both genotypes with HFD. However, HFD IL-6 MKO mice had lower (P < 0.05) inguinal adipose tissue (iWAT) mass than HFD Floxed mice. Accordingly, iWAT glucose transporter 4 (GLUT4) protein content, 5'AMP activated protein kinase (AMPK)(Thr172) phosphorylation, and fatty acid synthase (FAS) mRNA content were lower (P < 0.05) in IL-6 MKO than Floxed mice on Chow. In addition, iWAT AMPK(Thr172) and hormone-sensitive lipase (HSL)(Ser565) phosphorylation as well as perilipin protein content was higher (P < 0.05) in HFD IL-6 MKO than HFD Floxed mice, and pyruvate dehydrogenase E1α (PDH-E1α) protein content was higher (P < 0.05) in HFD ExTr IL-6 MKO than HFD ExTr Floxed mice. CONCLUSIONS These findings indicate that SkM IL-6 affects iWAT mass through regulation of glucose uptake capacity as well as lipogenic and lipolytic factors.
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Affiliation(s)
- Jakob G. Knudsen
- Department of BiologyCentre for Inflammation and Metabolism, The August Krogh Centre, University of CopenhagenCopenhagenDenmark
| | - Lærke Bertholdt
- Department of BiologyCentre for Inflammation and Metabolism, The August Krogh Centre, University of CopenhagenCopenhagenDenmark
| | - Ella Joensen
- Department of BiologyCentre for Inflammation and Metabolism, The August Krogh Centre, University of CopenhagenCopenhagenDenmark
| | - Signe B. Lassen
- Department of BiologyCentre for Inflammation and Metabolism, The August Krogh Centre, University of CopenhagenCopenhagenDenmark
| | - Juan Hidalgo
- Departamento die Biología Celular y FisiologíaUniversidad De Autonoma De BarcelonaBarcelonaSpain
| | - Henriette Pilegaard
- Department of BiologyCentre for Inflammation and Metabolism, The August Krogh Centre, University of CopenhagenCopenhagenDenmark
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Buzelle SL, MacPherson REK, Peppler WT, Castellani L, Wright DC. The contribution of IL-6 to beta 3 adrenergic receptor mediated adipose tissue remodeling. Physiol Rep 2015; 3:3/2/e12312. [PMID: 25713332 PMCID: PMC4393216 DOI: 10.14814/phy2.12312] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The chronic activation of beta 3 adrenergic receptors results in marked alterations in adipose tissue morphology and metabolism, including increases in mitochondrial content and the expression of enzymes involved in lipogenesis and glyceroneogenesis. Acute treatment with CL 316,243, a beta 3 adrenergic agonist, induces the expression of interleukin 6. Interestingly, IL-6 has been shown to induce mitochondrial genes in cultured adipocytes. Therefore, the purpose of this paper was to examine the role of interleukin 6 in mediating the in vivo effects of CL 316,243 in white adipose tissue. Circulating IL-6, and markers of IL-6 signaling in white adipose tissue were increased 4 h following a single injection of CL 316,243 in C57BL6/J mice. Once daily injections of CL 316,243 for 5 days increased the protein content of a number of mitochondrial proteins including CORE1, Cytochrome C, PDH, MCAD, and Citrate Synthase to a similar extent in adipose tissue from WT and IL-6−/− mice. Conversely, CL 316,243-induced increases in COXIV and phosphorylated AMPK were attenuated in IL-6−/− mice. Likewise, the slight, but significant, CL 316,243-induced increases in ATGL, PEPCK, and PPARγ, were reduced or absent in adipose tissue IL-6−/− mice. The attenuated response to CL 316,243 in white adipose tissue in IL-6−/− mice was associated with reductions in whole-body oxygen consumption and energy expenditure in the light phase. Our findings suggest that IL-6 plays a limited role in CL 316,243-mediated adipose tissue remodeling.
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Affiliation(s)
- Samyra L Buzelle
- Department of Biochemistry, Ribeirao Preto Medical School, University of Sao Paulo, Riberao Preto, Brazil
| | - Rebecca E K MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Willem T Peppler
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Livingston WS, Rusch HL, Nersesian PV, Baxter T, Mysliwiec V, Gill JM. Improved Sleep in Military Personnel is Associated with Changes in the Expression of Inflammatory Genes and Improvement in Depression Symptoms. Front Psychiatry 2015; 6:59. [PMID: 25983695 PMCID: PMC4415307 DOI: 10.3389/fpsyt.2015.00059] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 04/08/2015] [Indexed: 12/30/2022] Open
Abstract
STUDY OBJECTIVES Sleep disturbances are common in military personnel and are associated with increased risk for psychiatric morbidity, including posttraumatic stress disorder (PTSD) and depression, as well as inflammation. Improved sleep quality is linked to reductions in inflammatory bio-markers; however, the underlying mechanisms remain elusive. METHODS In this study, we examine whole genome expression changes related to improved sleep in 68 military personnel diagnosed with insomnia. Subjects were classified into the following groups and then compared: improved sleep (n = 46), or non-improved sleep (n = 22) following three months of standard of care treatment for insomnia. Within subject differential expression was determined from microarray data using the Partek Genomics Suite analysis program and the ingenuity pathway analysis (IPA) was used to determine key regulators of observed expression changes. Changes in symptoms of depression and PTSD were also compared. RESULTS At baseline, both groups were similar in demographics, clinical characteristics, and gene-expression profiles. The microarray data revealed that 217 coding genes were differentially expressed at the follow-up-period compared to baseline in the participants with improved sleep. Expression of inflammatory cytokines were reduced including IL-1β, IL-6, IL-8, and IL-13, with fold changes ranging from -3.19 to -2.1, and there were increases in the expression of inflammatory regulatory genes including toll-like receptors 1, 4, 7, and 8 in the improved sleep group. IPA revealed six gene networks, including ubiquitin, which was a major regulator in these gene-expression changes. The improved sleep group also had a significant reduction in the severity of depressive symptoms. CONCLUSION Interventions that restore sleep likely reduce the expression of inflammatory genes, which relate to ubiquitin genes and relate to reductions in depressive symptoms.
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Affiliation(s)
- Whitney S Livingston
- National Institutes of Nursing Research, National Institutes of Health , Bethesda, MD , USA
| | - Heather L Rusch
- National Institutes of Nursing Research, National Institutes of Health , Bethesda, MD , USA
| | - Paula V Nersesian
- National Institutes of Nursing Research, National Institutes of Health , Bethesda, MD , USA ; Johns Hopkins University School of Nursing , Baltimore, MD , USA
| | | | | | - Jessica M Gill
- National Institutes of Nursing Research, National Institutes of Health , Bethesda, MD , USA
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23
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Rogers RS, Beaudoin MS, Wheatley JL, Wright DC, Geiger PC. Heat shock proteins: in vivo heat treatments reveal adipose tissue depot-specific effects. J Appl Physiol (1985) 2014; 118:98-106. [PMID: 25554799 DOI: 10.1152/japplphysiol.00286.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Heat treatments (HT) and the induction of heat shock proteins (HSPs) improve whole body and skeletal muscle insulin sensitivity while decreasing white adipose tissue (WAT) mass. However, HSPs in WAT have been understudied. The purpose of the present study was to examine patterns of HSP expression in WAT depots, and to examine the effects of a single in vivo HT on WAT metabolism. Male Wistar rats received HT (41°C, 20 min) or sham treatment (37°C), and 24 h later subcutaneous, epididymal, and retroperitoneal WAT depots (SCAT, eWAT, and rpWAT, respectively) were removed for ex vivo experiments and Western blotting. SCAT, eWAT, and rpWAT from a subset of rats were also cultured separately and received a single in vitro HT or sham treatment. HSP72 and HSP25 expression was greatest in more metabolically active WAT depots (i.e., eWAT and rpWAT) compared with the SCAT. Following HT, HSP72 increased in all depots with the greatest induction occurring in the SCAT. In addition, HSP25 increased in the rpWAT and eWAT, while HSP60 increased in the rpWAT only in vivo. Free fatty acid (FFA) release from WAT explants was increased following HT in the rpWAT only, and fatty acid reesterification was decreased in the rpWAT but increased in the SCAT following HT. HT increased insulin responsiveness in eWAT, but not in SCAT or rpWAT. Differences in HSP expression and induction patterns following HT further support the growing body of literature differentiating distinct WAT depots in health and disease.
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Affiliation(s)
- Robert S Rogers
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas; and
| | - Marie-Soleil Beaudoin
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Joshua L Wheatley
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas; and
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Paige C Geiger
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas; and
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24
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MacPherson REK, Castellani L, Beaudoin MS, Wright DC. Evidence for fatty acids mediating CL 316,243-induced reductions in blood glucose in mice. Am J Physiol Endocrinol Metab 2014; 307:E563-70. [PMID: 25096179 PMCID: PMC4187028 DOI: 10.1152/ajpendo.00287.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CL 316,243, a β3-adrenergic agonist, was developed as an antiobesity and diabetes drug and causes rapid decreases in blood glucose levels in mice. The mechanisms mediating this effect have not been fully elucidated; thus, the purpose of the current study was to examine the role of fatty acids and interleukin-6, reputed mediators of insulin secretion, in this process. To address this question, we used physiological and pharmacological approaches in combination with knockout mouse models. CL 316,243 treatment in male C57BL6 mice increased plasma fatty acids, glycerol, interleukin-6, and insulin and reduced blood glucose concentrations 2 h following injections. The ability of CL 316,243 to increase insulin and fatty acids and reduce glucose was preserved in interleukin-6-deficient mice. CL 316,243-induced drops in blood glucose occurred in parallel with increases in circulating fatty acids but prior to increases in plasma interleukin-6. CL 316,243-mediated increases in plasma insulin levels and reductions in blood glucose were attenuated when mice were pretreated with the lipase inhibitor nicotinic acid or in whole body adipose tissue triglyceride lipase knockout mice. Collectively, our findings demonstrate an important role for fatty acids in mediating the effects of CL 316,243 in mice. Not only do our results provide new insight into the mechanisms of action of CL 316,243, but they also hint at an unappreciated aspect of adipose tissue -pancreas cross-talk.
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Affiliation(s)
- Rebecca E K MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Marie-Soleil Beaudoin
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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25
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Peake JM, Tan SJ, Markworth JF, Broadbent JA, Skinner TL, Cameron-Smith D. Metabolic and hormonal responses to isoenergetic high-intensity interval exercise and continuous moderate-intensity exercise. Am J Physiol Endocrinol Metab 2014; 307:E539-52. [PMID: 25096178 DOI: 10.1152/ajpendo.00276.2014] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study investigated the effects of high-intensity interval training (HIIT) vs. work-matched moderate-intensity continuous exercise (MOD) on metabolism and counterregulatory stress hormones. In a randomized and counterbalanced order, 10 well-trained male cyclists and triathletes completed a HIIT session [81.6 ± 3.7% maximum oxygen consumption (V̇o2 max); 72.0 ± 3.2% peak power output; 792 ± 95 kJ] and a MOD session (66.7 ± 3.5% V̇o2 max; 48.5 ± 3.1% peak power output; 797 ± 95 kJ). Blood samples were collected before, immediately after, and 1 and 2 h postexercise. Carbohydrate oxidation was higher (P = 0.037; 20%), whereas fat oxidation was lower (P = 0.037; -47%) during HIIT vs. MOD. Immediately after exercise, plasma glucose (P = 0.024; 20%) and lactate (P < 0.01; 5.4×) were higher in HIIT vs. MOD, whereas total serum free fatty acid concentration was not significantly different (P = 0.33). Targeted gas chromatography-mass spectromtery metabolomics analysis identified and quantified 49 metabolites in plasma, among which 11 changed after both HIIT and MOD, 13 changed only after HIIT, and 5 changed only after MOD. Notable changes included substantial increases in tricarboxylic acid intermediates and monounsaturated fatty acids after HIIT and marked decreases in amino acids during recovery from both trials. Plasma adrenocorticotrophic hormone (P = 0.019), cortisol (P < 0.01), and growth hormone (P < 0.01) were all higher immediately after HIIT. Plasma norepinephrine (P = 0.11) and interleukin-6 (P = 0.20) immediately after exercise were not significantly different between trials. Plasma insulin decreased during recovery from both HIIT and MOD (P < 0.01). These data indicate distinct differences in specific metabolites and counterregulatory hormones following HIIT vs. MOD and highlight the value of targeted metabolomic analysis to provide more detailed insights into the metabolic demands of exercise.
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Affiliation(s)
- Jonathan M Peake
- School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia; Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Australia;
| | - Sok Joo Tan
- School of Human Movement Studies, The University of Queensland, Brisbane, Australia; and
| | | | - James A Broadbent
- School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Tina L Skinner
- School of Human Movement Studies, The University of Queensland, Brisbane, Australia; and
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Wan Z, Durrer C, Mah D, Simtchouk S, Little JP. One-week high-fat diet leads to reduced toll-like receptor 2 expression and function in young healthy men. Nutr Res 2014; 34:1045-51. [PMID: 25245200 DOI: 10.1016/j.nutres.2014.08.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/25/2014] [Accepted: 08/27/2014] [Indexed: 01/22/2023]
Abstract
Toll-like receptor 2 (TLR2) is implicated in inflammatory responses to high-fat diet (HFD)-induced obesity in rodents, but human HFD studies examining TLR2-mediated immune responses are lacking. Our aim was to determine whether HFD affected TLR2 function in humans. We hypothesized that a short-term HFD in humans would impair TLR2-mediated immune function. Fasting blood samples were obtained from healthy young men (N = 9) before and after a 7-day HFD. Toll-like receptor 2 function was assessed in ex vivo whole blood cultures stimulated with the TLR2 agonist N-palmitoyl-S-[2,3-bis[palmitoyloxy]-[2RS]-propyl]-[R]-cysteinyl-[S]-seryl-[S]-lysyl-[S]-lysyl-[S]-lysyl-[S]-lysine (Pam3-Cys-SK4). Peripheral blood mononuclear cells (PBMCs) were isolated to examine TLR2, TLR4, and p47 subunit of nicotinamide adenine dinucleotide phosphate oxidase (p47(phox)) protein expression via Western blotting. Pam3-Cys-SK4-stimulated secretion of interleukin-1β (-35%, P = .005), interleukin-6 (-32%, P = .01), and tumor necrosis factor-α (-33%, P = .06) was reduced following the HFD. High-fat diet resulted in decreased TLR2 (P = .049) and p47(phox) (P = .037) protein expression from PBMCs. To mimic lipid overload ex vivo, follow-up experiments were performed in whole blood cultures exposed to a mixture of free fatty acids for 24 hours; and surface protein expression of TLR2 and TLR4 on CD14+ monocytes was measured by flow cytometry. Free fatty acid exposure for 24 hours ex vivo reduced monocyte TLR2 levels by about 20% (P = .028). A 7-day HFD in young healthy men resulted in impaired TLR2 function. Decreased TLR2 and p47(phox) protein expression in PBMCs, possibly due to excess free fatty acids, may mediate this response. Our current findings indicate that impaired TLR2 response after HFD might be partially responsible for increased risk of infection in diet-induced obesity.
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Affiliation(s)
- Zhongxiao Wan
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia.
| | - Cody Durrer
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia.
| | - Dorrian Mah
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia.
| | - Svetlana Simtchouk
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia.
| | - Jonathan P Little
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia.
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27
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Beaudoin MS, Snook LA, Arkell AM, Stefanson A, Wan Z, Simpson JA, Holloway GP, Wright DC. Novel effects of rosiglitazone on SMAD2 and SMAD3 signaling in white adipose tissue of diabetic rats. Obesity (Silver Spring) 2014; 22:1632-42. [PMID: 24500776 DOI: 10.1002/oby.20717] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 01/30/2014] [Accepted: 01/31/2014] [Indexed: 12/17/2022]
Abstract
OBJECTIVE The effects of the proliferator-activated receptor gamma (PPARγ) agonist rosiglitazone (ROSI) on the transforming growth factor (TGF)-β/SMAD signaling pathway in white adipose tissue (WAT) of diabetic rats were assessed. METHODS Six-week-old, male ZDF rats were fed a chow diet with (ZDF ROSI) or without (ZDF chow) ROSI (diet, 100 mg/kg) for 6 weeks. Subcutaneous (scWAT) and retroperitoneal (rpWAT) adipose tissues were excised to quantify the protein content/phosphorylation. RESULTS ZDF ROSI animals showed enhanced glucose tolerance and mitochondrial protein content in both depots. The protein content of enzymes involved in fatty acid handling was increased in scWAT of ZDF ROSI animals. ZDF ROSI exhibited decreased phosphorylation of SMAD2 and SMAD3 exclusively in scWAT, along with increases in inhibitory SMAD7 and the E3 ubiquitin ligase SMURF2. In contrast, ROSI increased the protein content of SMAD4, TGF-β receptor I and II, and SMAD Anchor for Receptor Activation in scWAT. CONCLUSIONS For the first time, the fact that ROSI inhibits SMAD2 and SMAD3 signaling in a depot-specific manner in diabetic rats was demonstrated. In scWAT, ROSI reduced SMAD2 and SMAD3 phosphorylation, likely through the inhibitory actions of SMAD7 and SMURF2. Induction of proximal components of the SMAD pathway may constitute a feedback mechanism to counteract ROSI-induced lipid synthesis in scWAT.
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Affiliation(s)
- Marie-Soleil Beaudoin
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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28
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Castellani L, Root-Mccaig J, Frendo-Cumbo S, Beaudoin MS, Wright DC. Exercise training protects against an acute inflammatory insult in mouse epididymal adipose tissue. J Appl Physiol (1985) 2014; 116:1272-80. [PMID: 24674860 DOI: 10.1152/japplphysiol.00074.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Exercise training reduces systemic and adipose tissue inflammation. However, these beneficial effects seem to be largely tied to reductions in adipose tissue mass. The purpose of the present study was to determine if exercise training confers a protective effect against an acute inflammatory challenge. We hypothesized that the induction of inflammatory markers, such as interleukin 6 (IL-6), suppressor of cytokine signaling 3 (SOCS3), and TNF-α by the beta-3 adrenergic agonist CL 316,243 would be reduced in adipose tissue from trained mice and this would be associated with reductions in transient receptor potential cation channel 4 (TRPV4), a protein recently shown to regulate the expression of proinflammatory cytokines. Exercise training (4 wk of treadmill running, 1 h/day, 5 days/wk) increased markers of skeletal muscle mitochondrial content and the induction of PPAR-gamma coactivator 1 alpha in epididymal adipose tissue. The mRNA expression of IL-6, SOCS3, and TNFα were not different in subcutaneous and epididymal adipose tissue from sedentary and trained mice; however, the CL 316,243-mediated induction of these genes was attenuated ∼50% in epididymal adipose tissue from trained mice as were increases in plasma IL-6. The effects of training were not explained by reductions in lipolytic responsiveness, but were associated with decreases in TRPV4 protein content. These results highlight a previously unappreciated anti-inflammatory effect of exercise training on adipose tissue immunometabolism and underscores the value of assessing adipose tissue inflammation in the presence of an inflammatory insult.
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Affiliation(s)
- Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jared Root-Mccaig
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Scott Frendo-Cumbo
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Marie-Soleil Beaudoin
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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29
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Bosma M. Lipid homeostasis in exercise. Drug Discov Today 2014; 19:1019-23. [PMID: 24632001 DOI: 10.1016/j.drudis.2014.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 03/06/2014] [Indexed: 01/08/2023]
Abstract
Fatty acids (FA) are essential energy substrates during endurance exercise. In addition to systemic supply, intramyocellular neutral lipids form an important source of FA for the working muscle. Endurance exercise training is associated with an increased reliance on lipids as a fuel source, has systemic lipid-lowering effects and results in a remodeling of skeletal muscle lipid metabolism toward increased oxidation, neutral lipid storage and turnover. Interestingly, recent studies have indicated common exercise-induced regulatory pathways for genes involved in skeletal muscle mitochondrial oxidative metabolism and lipid droplet (LD) dynamics. In this review, I discuss lipid homeostasis during acute exercise and adaptations in lipid metabolism upon exercise training in the light of recent advances in the field.
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Affiliation(s)
- Madeleen Bosma
- Department of Cell and Molecular Biology, Karolinska Institutet, PO Box 285, SE-171 77 Stockholm, Sweden.
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30
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Wan Z, Root-McCaig J, Castellani L, Kemp BE, Steinberg GR, Wright DC. Evidence for the role of AMPK in regulating PGC-1 alpha expression and mitochondrial proteins in mouse epididymal adipose tissue. Obesity (Silver Spring) 2014; 22:730-8. [PMID: 23963743 DOI: 10.1002/oby.20605] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 08/12/2013] [Indexed: 12/24/2022]
Abstract
OBJECTIVE PGC-1α is a transcriptional co-activator and master regulator of mitochondrial biogenesis. While extensively studied in skeletal and cardiac muscle, recent findings suggest that white adipose tissue PGC-1α plays an important role in regulating glucose homeostasis. The purpose of the present investigation was to evaluate the role of AMPK in regulating PGC-1α and mitochondrial enzymes in mouse epididymal and inguinal subcutaneous adipose tissue. METHODS Mitochondrial protein content and norepinephrine and CL 316,243-induced PGC-1α mRNA expression were studied in mouse epididymal and inguinal adipose tissue from wild-type and AMPK β1(-/-) mice. RESULTS The protein content and phosphorylation of AMPKα was reduced in epididymal adipose tissue from AMPK β1(-/-) compared to WT mice, concomitant with decreases in PGC-1α and mitochondrial marker proteins. Norepinephrine and CL 316,243-mediated induction of PGC-1α were decreased in cultured epididymal adipose tissue from AMPK β1(-/-) relative to WT mice. In inguinal adipose tissue from AMPK β1(-/-) mice, mitochondrial marker protein content and norepinephrine and CL 316,243-mediated increases in PGC-1α were normal despite reductions in the content and phosphorylation of AMPKα. CONCLUSIONS Norepinephrine- and CL 316,243-mediated induction of PGC-1α and mitochondrial protein expression is regulated by AMPK in epididymal, but not inguinal adipose tissue.
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Affiliation(s)
- Zhongxiao Wan
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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31
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Knudsen JG, Murholm M, Carey AL, Biensø RS, Basse AL, Allen TL, Hidalgo J, Kingwell BA, Febbraio MA, Hansen JB, Pilegaard H. Role of IL-6 in exercise training- and cold-induced UCP1 expression in subcutaneous white adipose tissue. PLoS One 2014; 9:e84910. [PMID: 24416310 PMCID: PMC3885654 DOI: 10.1371/journal.pone.0084910] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/28/2013] [Indexed: 01/22/2023] Open
Abstract
Expression of brown adipose tissue (BAT) associated proteins like uncoupling protein 1 (UCP1) in inguinal WAT (iWAT) has been suggested to alter iWAT metabolism. The aim of this study was to investigate the role of interleukin-6 (IL-6) in exercise training and cold exposure-induced iWAT UCP1 expression. The effect of daily intraperitoneal injections of IL-6 (3 ng/g) in C57BL/6 mice for 7 days on iWAT UCP1 expression was examined. In addition, the expression of UCP1 in iWAT was determined in response to 3 days of cold exposure (4°C) and 5 weeks of exercise training in wild type (WT) and whole body IL-6 knockout (KO) mice. Repeated injections of IL-6 in C57BL/6 mice increased UCP1 mRNA but not UCP1 protein content in iWAT. Cold exposure increased iWAT UCP1 mRNA content similarly in IL-6 KO and WT mice, while exercise training increased iWAT UCP1 mRNA in WT mice but not in IL-6 KO mice. Additionally, a cold exposure-induced increase in iWAT UCP1 protein content was blunted in IL-6 KO mice, while UCP1 protein content in iWAT was lower in both untrained and exercise trained IL-6 KO mice than in WT mice. In conclusion, repeated daily increases in plasma IL-6 can increase iWAT UCP1 mRNA content and IL-6 is required for an exercise training-induced increase in iWAT UCP1 mRNA content. In addition IL-6 is required for a full induction of UCP1 protein expression in response to cold exposure and influences the UCP1 protein content iWAT of both untrained and exercise trained animals.
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Affiliation(s)
- Jakob G. Knudsen
- Centre of Inflammation and Metabolism, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Maria Murholm
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andrew L. Carey
- Metabolic and Vascular Physiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Rasmus S. Biensø
- Centre of Inflammation and Metabolism, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Astrid L. Basse
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tamara L. Allen
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Juan Hidalgo
- Department of Neuroscience, Universidad Autonoma de Barcelona, Barcelona, Spain
| | - Bronwyn A. Kingwell
- Metabolic and Vascular Physiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Mark A. Febbraio
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Jacob B. Hansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Centre of Inflammation and Metabolism, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
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Abstract
Type 2 diabetes and obesity are very serious health problems in both developed and developing countries. An increased level of GH is known to promote insulin resistance. Transgenic (Tg) mice over-expressing bovine GH are short-living and characterized, among other traits, by hyperinsulinemia and increased insulin resistance in comparison with normal (N) mice. Pioglitazone (PIO) is a member of the thiazolidinediones - a group of insulin-sensitizing drugs that are selective agonists of peroxisome proliferator-activated receptor gamma (PPARγ). The aim of the study was to analyze the effects of PIO on the insulin-signaling pathway in Tg and N mice. Plasma levels of insulin and glucose as well as hepatic levels of proteins involved in insulin signaling were analyzed by ELISA or western blot methods. Treatment with PIO decreased plasma level of glucose in N mice only. Similarly, PIO increased insulin sensitivity (expressed as the relative insulin sensitivity index; RISI) only in N mice. In the liver, PIO decreased the phosphorylation of insulin receptor substrate-1 (IRS1) at a serine residue (Ser(307)-pS-IRS1), which inhibits insulin action, and had a tendency to increase tyrosine phosphorylation of IRS2 (Tyr-pY-IRS2) only in N mice but did not affect either of these parameters in Tg mice. Levels of total and phosphorylated mammalian target of rapamycin were increased in Tg mice. Moreover, the level of AKT2 was decreased by PIO in N mice only. In conclusion, the lack of improvement of insulin sensitivity in insulin-resistant Tg mice during PIO treatment indicates that chronically elevated GH levels can inhibit the beneficial effects of PIO on insulin signaling.
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Affiliation(s)
- Adam Gesing
- Department of Internal Medicine, Geriatrics Research, Southern Illinois University School of Medicine, 801 N Rutledge St., Room 4389, 62794-9628, Springfield, IL, USA
- Department of Oncological Endocrinology, Medical University of Lodz, Zeligowski St., No 7/9, 90-752 Lodz, Poland
- CORRESPONDING AUTHOR: Dr. Adam Gesing, M.D., Ph.D., Department of Oncological Endocrinology, Medical University of Lodz, Zeligowski St., No 7/9, 90-752 Lodz, Poland, Phone: + 48 42 6393122, Fax: + 48 42 6393121, ,
| | - Andrzej Bartke
- Department of Internal Medicine, Geriatrics Research, Southern Illinois University School of Medicine, 801 N Rutledge St., Room 4389, 62794-9628, Springfield, IL, USA
| | - Michal M. Masternak
- College of Medicine, Burnett School of Biomedical Sciences, University of Central Florida, 6900 Lake Nona Blvd, Orlando, FL 32827, USA
- Institute of Human Genetics, Polish Academy of Sciences, Strzeszynska St., No 32, 60-479 Poznan, Poland
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Macdonald TL, Wan Z, Frendo-Cumbo S, Dyck DJ, Wright DC. IL-6 and epinephrine have divergent fiber type effects on intramuscular lipolysis. J Appl Physiol (1985) 2013; 115:1457-63. [PMID: 24052031 DOI: 10.1152/japplphysiol.00558.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
IL-6 is an exercise-regulated myokine that has been suggested to increase lipolysis in fast-twitch skeletal muscle. However, it is not known if a similar effect is present in slow-twitch muscle. Furthermore, epinephrine increases IL-6 secretion from skeletal muscle, suggesting that IL-6 could play a role in mediating the lipolytic effects of catecholamines. The purpose of this study was to determine whether IL-6 stimulates skeletal muscle lipolysis in a fiber type dependent manner and is required for epinephrine-stimulated lipolysis in murine skeletal muscle. Soleus and extensor digitorum longus (EDL) muscles from male C57BL/6J wild-type and IL-6(-/-) mice were incubated with 1 μM (183 ng/ml) epinephrine or 75 ng/ml recombinant IL-6 (rIL-6) for 60 min. IL-6 treatment increased 5'-AMP-activated protein kinase and signal transducer and activator of transcription 3 phosphorylation and glycerol release in isolated EDL but not soleus muscles from C57BL/6J mice. Conversely, epinephrine increased glycerol release in soleus but not EDL muscles from C57BL/6J mice. Basal lipolysis was elevated in soleus muscle from IL-6(-/-) mice, and this was associated with increases in adipose triglyceride lipase (ATGL) and its coactivator comparative gene identification-58 (CGI-58). The increase in ATGL content does not appear to be due to a loss of IL-6's direct effects, because ex vivo treatment with IL-6 failed to alter the expression of ATGL mRNA in soleus muscle. In summary, IL-6 stimulates lipolysis in glycolytic but not oxidative muscle, whereas the opposite fiber type effect is seen with epinephrine. The absence of IL-6 indirectly upregulates lipolysis, and this is associated with increases in ATGL and its coactivator CGI-58.
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Affiliation(s)
- Tara L Macdonald
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Ontario, Canada
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Beaudoin MS, Snook LA, Arkell AM, Simpson JA, Holloway GP, Wright DC. Resveratrol supplementation improves white adipose tissue function in a depot-specific manner in Zucker diabetic fatty rats. Am J Physiol Regul Integr Comp Physiol 2013; 305:R542-51. [DOI: 10.1152/ajpregu.00200.2013] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resveratrol (RSV) is a polyphenolic compound suggested to have anti-diabetic properties. Surprisingly, little is known regarding the effects of RSV supplementation on adipose tissue (AT) metabolism in vivo. The purpose of this study was to assess the effects of RSV on mitochondrial content and respiration, glyceroneogenesis (GNG), and adiponectin secretion in adipose tissue from Zucker diabetic fatty (ZDF) rats. Five-week-old ZDF rats were fed a chow diet with (ZDF RSV) or without (ZDF chow) RSV (200 mg/kg body wt) for 6 wk. Changes in adipose tissue metabolism were assessed in subcutaneous (scAT) and intra-abdominal [retroperitoneal (rpWAT), epididymal (eWAT)] adipose tissue depots. ZDF RSV rats showed lower fasting glucose and higher circulating adiponectin, as well as lower glucose area under the curve during intraperitoneal glucose and insulin tolerance tests than ZDF chow. [14C]pyruvate incorporation into triglycerides and adiponectin secretion were higher in scAT from ZDF RSV rats, concurrent with increases in adipose tissue triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and the phosphorylation of pyruvate dehydrogenase-E1α (PDH) (Ser293) protein content in this depot. Moreover, uncoupled mitochondrial respiration and complex I and II-supported respiration were increased in both scAT and rpWAT, which correlated with increases in cytochrome c oxidase subunit IV (COX4) protein content. In vitro treatment of scAT with RSV (50 μmol/l; 24 h) induced pyruvate dehydrogenase kinase 4 (PDK4) and peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α) mRNA expression. Collectively, these data demonstrate that RSV can induce adipose tissue mitochondrial biogenesis in parallel with increases in GNG and adiponectin secretion.
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Affiliation(s)
- Marie-Soleil Beaudoin
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Laelie A. Snook
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Alicia M. Arkell
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jeremy A. Simpson
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Graham P. Holloway
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C. Wright
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Wright DC. Exercise- and resveratrol-mediated alterations in adipose tissue metabolism. Appl Physiol Nutr Metab 2013; 39:109-16. [PMID: 24476464 DOI: 10.1139/apnm-2013-0316] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Owing to its obligatory role in locomotion and the fact that it accounts for the vast majority of whole-body glucose and lipid oxidation, much work has focused on studying the biochemical adaptations that occur in skeletal muscle in response to exercise. However, over the past several years there has been a growing appreciation that adipose tissue is an important player in regulating systemic carbohydrate and lipid homeostasis. Despite this, the examination of how exercise alters adipose tissue function and metabolism is, when compared with skeletal muscle, in its infancy. The purpose of the current review is to highlight some of the recent findings from our laboratory and others that focus on the emerging area of adipose tissue exercise biochemistry. Specifically, the role of exercise on the induction of mitochondrial and glyceroneogenic enzymes will be examined and will be compared with the well-characterized effects of thiazolidinediones, which are insulin-sensitizing drugs. A particular emphasis will be placed on the role of interleukin-6 in mediating the effects of exercise. Finally, we will discuss recent data from our laboratory demonstrating beneficial effects of resveratrol supplementation on adipose tissue metabolism.
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Affiliation(s)
- David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph ON N1G 2W1, Canada
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Williams CB, Zelt JGE, Castellani LN, Little JP, Jung ME, Wright DC, Tschakovsky ME, Gurd BJ. Changes in mechanisms proposed to mediate fat loss following an acute bout of high-intensity interval and endurance exercise. Appl Physiol Nutr Metab 2013; 38:1236-44. [PMID: 24195624 DOI: 10.1139/apnm-2013-0101] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The purpose of this study was to investigate the acute effects of endurance exercise (END; 65% V̇O2peak for 60 min) and high-intensity interval exercise (HIE; four 30 s Wingates separated by 4.5 min of active rest) on cardiorespiratory, hormonal, and subjective appetite measures that may account for the previously reported superior fat loss with low volume HIE compared with END. Recreationally active males (n = 18) completed END, HIE, and control (CON) protocols. On each test day, cardiorespiratory measures including oxygen uptake (V̇O2), respiratory exchange ratio (RER), and heart rate were recorded and blood samples were obtained at baseline (BSL), 60 min after exercise, and 180 min after exercise (equivalent times for CON). Subjective measures of appetite (hunger, fullness, nausea, and prospective consumption) were assessed using visual analogue scales, administered at BSL, 0, 60, 120, and 180 min after exercise. No significant differences in excess postexercise oxygen consumption (EPOC) were observed between conditions. RER was significantly (P < 0.05) depressed in HIE compared with CON at 60 min after exercise, yet estimates of total fat oxidation over CON were not different between HIE and END. No differences in plasma adiponectin concentrations between protocols or time points were present. Epinephrine and norepinephrine were significantly (P < 0.05) elevated immediately after exercise in HIE compared with CON. Several subjective measures of appetite were significantly (P < 0.05) depressed immediately following HIE. Our data indicate that increases in EPOC or fat oxidation following HIE appear unlikely to contribute to the reported superior fat loss compared with END.
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Affiliation(s)
- Cameron B Williams
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON K7L 3N6, Canada
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Flachs P, Rossmeisl M, Kuda O, Kopecky J. Stimulation of mitochondrial oxidative capacity in white fat independent of UCP1: A key to lean phenotype. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:986-1003. [DOI: 10.1016/j.bbalip.2013.02.003] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/06/2013] [Accepted: 02/09/2013] [Indexed: 02/06/2023]
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Role of AMP-activated protein kinase in adipose tissue metabolism and inflammation. Clin Sci (Lond) 2013; 124:491-507. [PMID: 23298225 DOI: 10.1042/cs20120536] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AMPK (AMP-activated protein kinase) is a key regulator of cellular and whole-body energy balance. AMPK phosphorylates and regulates many proteins concerned with nutrient metabolism, largely acting to suppress anabolic ATP-consuming pathways while stimulating catabolic ATP-generating pathways. This has led to considerable interest in AMPK as a therapeutic target for the metabolic dysfunction observed in obesity and insulin resistance. The role of AMPK in skeletal muscle and the liver has been extensively studied, such that AMPK has been demonstrated to inhibit synthesis of fatty acids, cholesterol and isoprenoids, hepatic gluconeogenesis and translation while increasing fatty acid oxidation, muscle glucose transport, mitochondrial biogenesis and caloric intake. The role of AMPK in the other principal metabolic and insulin-sensitive tissue, adipose, remains poorly characterized in comparison, yet increasing evidence supports an important role for AMPK in adipose tissue function. Obesity is characterized by hypertrophy of adipocytes and the development of a chronic sub-clinical pro-inflammatory environment in adipose tissue, leading to increased infiltration of immune cells. This combination of dysfunctional hypertrophic adipocytes and a pro-inflammatory environment contributes to insulin resistance and the development of Type 2 diabetes. Exciting recent studies indicate that AMPK may not only influence metabolism in adipocytes, but also act to suppress this pro-inflammatory environment, such that targeting AMPK in adipose tissue may be desirable to normalize adipose dysfunction and inflammation. In the present review, we discuss the role of AMPK in adipose tissue, focussing on the regulation of carbohydrate and lipid metabolism, adipogenesis and pro-inflammatory pathways in physiological and pathophysiological conditions.
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Wan Z, Matravadia S, Holloway GP, Wright DC. FAT/CD36 regulates PEPCK expression in adipose tissue. Am J Physiol Cell Physiol 2013; 304:C478-84. [PMID: 23302781 DOI: 10.1152/ajpcell.00372.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fatty acid translocase (FAT)/CD36 has been extensively studied for its role in facilitating fatty acid uptake. Recent findings have also demonstrated that this protein regulates adipocyte lipolysis and may modulate fatty acid reesterification. As FAT/CD36 has been shown to control the expression of genes involved in fatty acid oxidation in adipocytes, we reasoned that this protein might also control the expression of enzymes involved in fatty acid reesterification. In adipose tissue from FAT/CD36 knockout (KO) mice, we found that glycerol and fatty acid release were reduced and this was associated with reductions in adipose triglyceride lipase. Decreases in lipolysis were paralleled by increases in the free fatty acid-to-glycerol ratio and reductions in primary and fractional rates of fatty acid reesterfication in cultured adipose tissue from FAT/CD36 KO mice. Reductions in reesterfication were associated with decreases in the mRNA expression and protein content of phosphoenolpyruvate carboxykinase (PEPCK). To determine if reductions in lipolysis could lead to decreases in PEPCK mRNA expression, we treated cultured mouse adipose tissue with the lipase inhibitor CAY10499 (2 μM) and found that this resulted in an ∼50% reduction in PEPCK mRNA expression. Treatment with hexarelin (10 μM, 12 h), a CD36 agonist, increased PEPCK mRNA expression independent of lipolysis. Collectively, our results provide novel evidence that FAT/CD36 regulates PEPCK in adipose tissue and that this could be secondary to reductions in lipolysis.
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Affiliation(s)
- Zhongxiao Wan
- Department of Agriculture, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada
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Wan Z, Perry CGR, Macdonald T, Chan CB, Holloway GP, Wright DC. IL-6 is not necessary for the regulation of adipose tissue mitochondrial content. PLoS One 2012; 7:e51233. [PMID: 23240005 PMCID: PMC3519867 DOI: 10.1371/journal.pone.0051233] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 10/31/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Adipose tissue mitochondria have been implicated as key mediators of systemic metabolism. We have shown that IL-6 activates AMPK, a mediator of mitochondrial biogenesis, in adipose tissue; however, IL-6(-/-) mice fed a high fat diet have been reported to develop insulin resistance. These findings suggest that IL-6 may control adipose tissue mitochondrial content in vivo, and that reductions in adipose tissue mitochondria may be causally linked to the development of insulin resistance in IL-6(-/-) mice fed a high fat diet. On the other hand, IL-6 has been implicated as a negative regulator of insulin action. Given these discrepancies the purpose of the present investigation was to further evaluate the relationship between IL-6, adipose tissue mitochondrial content and whole body insulin action. METHODOLOGY AND PRINCIPAL FINDINGS In cultured epididymal mouse adipose tissue IL-6 (75 ng/ml) induced the expression of the transcriptional co-activators PGC-1α and PRC, reputed mediators of mitochondrial biogenesis. Similarly, IL-6 increased the expression of COXIV and CPT-1. These effects were absent in cultured subcutaneous adipose tissue and were associated with lower levels of GP130 and IL-6 receptor alpha protein content. Markers of mitochondrial content were intact in adipose tissue from chow fed IL-6(-/-) mice. When fed a high fat diet IL-6(-/-) mice were more glucose and insulin intolerant than controls fed the same diet; however this was not explained by decreases in adipose tissue mitochondrial content or respiration. CONCLUSIONS AND SIGNIFICANCE Our findings demonstrate depot-specific differences in the ability of IL-6 to induce PGC-1α and mitochondrial enzymes and demonstrate that IL-6 is not necessary for the maintenance of adipose tissue mitochondrial content in vivo. Moreover, reductions in adipose tissue mitochondria do not explain the greater insulin resistance in IL-6(-/-) mice fed a high fat diet. These results question the role of adipose tissue mitochondrial dysfunction in the etiology of insulin resistance.
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Affiliation(s)
- Zhongxiao Wan
- Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
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