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O'Neill HM, Lally JS, Galic S, Pulinilkunnil T, Ford RJ, Dyck JRB, van Denderen BJ, Kemp BE, Steinberg GR. Skeletal muscle ACC2 S212 phosphorylation is not required for the control of fatty acid oxidation during exercise. Physiol Rep 2015; 3:3/7/e12444. [PMID: 26156967 PMCID: PMC4552526 DOI: 10.14814/phy2.12444] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
During submaximal exercise fatty acids are a predominant energy source for muscle contractions. An important regulator of fatty acid oxidation is acetyl-CoA carboxylase (ACC), which exists as two isoforms (ACC1 and ACC2) with ACC2 predominating in skeletal muscle. Both ACC isoforms regulate malonyl-CoA production, an allosteric inhibitor of carnitine palmitoyltransferase 1 (CPT-1); the primary enzyme controlling fatty acyl-CoA flux into mitochondria for oxidation. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is activated during exercise or by pharmacological agents such as metformin and AICAR. In resting muscle the activation of AMPK with AICAR leads to increased phosphorylation of ACC (S79 on ACC1 and S221 on ACC2), which reduces ACC activity and malonyl-CoA; effects associated with increased fatty acid oxidation. However, whether this pathway is vital for regulating skeletal muscle fatty acid oxidation during conditions of increased metabolic flux such as exercise/muscle contractions remains unknown. To examine this we characterized mice lacking AMPK phosphorylation sites on ACC2 (S212 in mice/S221 in humans-ACC2-knock-in [ACC2-KI]) or both ACC1 (S79) and ACC2 (S212) (ACC double knock-in [ACCD-KI]) during submaximal treadmill exercise and/or ex vivo muscle contractions. We find that surprisingly, ACC2-KI mice had normal exercise capacity and whole-body fatty acid oxidation during treadmill running despite elevated muscle ACC2 activity and malonyl-CoA. Similar results were observed in ACCD-KI mice. Fatty acid oxidation was also maintained in muscles from ACC2-KI mice contracted ex vivo. These findings indicate that pathways independent of ACC phosphorylation are important for regulating skeletal muscle fatty acid oxidation during exercise/muscle contractions.
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Affiliation(s)
- Hayley M O'Neill
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada Department of Medicine, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia Faculty of Health Sciences and Medicine, Bond Institute of Health and Sport, Bond University, Robina, Queensland, Australia
| | - James S Lally
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Sandra Galic
- Department of Medicine, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia
| | - Thomas Pulinilkunnil
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Rebecca J Ford
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Jason R B Dyck
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Bryce J van Denderen
- Department of Medicine, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia
| | - Bruce E Kemp
- Department of Medicine, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia
| | - Gregory R Steinberg
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada Department of Medicine, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia
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52
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Hocking SL, Stewart RL, Brandon AE, Suryana E, Stuart E, Baldwin EM, Kolumam GA, Modrusan Z, Junutula JR, Gunton JE, Medynskyj M, Blaber SP, Karsten E, Herbert BR, James DE, Cooney GJ, Swarbrick MM. Subcutaneous fat transplantation alleviates diet-induced glucose intolerance and inflammation in mice. Diabetologia 2015; 58:1587-600. [PMID: 25899451 DOI: 10.1007/s00125-015-3583-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 03/13/2015] [Indexed: 12/26/2022]
Abstract
AIMS/HYPOTHESIS Adipose tissue (AT) distribution is a major determinant of mortality and morbidity in obesity. In mice, intra-abdominal transplantation of subcutaneous AT (SAT) protects against glucose intolerance and insulin resistance (IR), but the underlying mechanisms are not well understood. METHODS We investigated changes in adipokines, tissue-specific glucose uptake, gene expression and systemic inflammation in male C57BL6/J mice implanted intra-abdominally with either inguinal SAT or epididymal visceral AT (VAT) and fed a high-fat diet (HFD) for up to 17 weeks. RESULTS Glucose tolerance was improved in mice receiving SAT after 6 weeks, and this was not attributable to differences in adiposity, tissue-specific glucose uptake, or plasma leptin or adiponectin concentrations. Instead, SAT transplantation prevented HFD-induced hepatic triacylglycerol accumulation and normalised the expression of hepatic gluconeogenic enzymes. Grafted fat displayed a significant increase in glucose uptake and unexpectedly, an induction of skeletal muscle-specific gene expression. Mice receiving subcutaneous fat also displayed a marked reduction in the plasma concentrations of several proinflammatory cytokines (TNF-α, IL-17, IL-12p70, monocyte chemoattractant protein-1 [MCP-1] and macrophage inflammatory protein-1β [ΜIP-1β]), compared with sham-operated mice. Plasma IL-17 and MIP-1β concentrations were reduced from as early as 4 weeks after transplantation, and differences in plasma TNF-α and IL-17 concentrations predicted glucose tolerance and insulinaemia in the entire cohort of mice (n = 40). In contrast, mice receiving visceral fat transplants were glucose intolerant, with increased hepatic triacylglycerol content and elevated plasma IL-6 concentrations. CONCLUSIONS/INTERPRETATION Intra-abdominal transplantation of subcutaneous fat reverses HFD-induced glucose intolerance, hepatic triacylglycerol accumulation and systemic inflammation in mice.
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Affiliation(s)
- Samantha L Hocking
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, 2010, Sydney, NSW, Australia
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53
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Valsangkar DS, Downs SM. Acetyl CoA carboxylase inactivation and meiotic maturation in mouse oocytes. Mol Reprod Dev 2015; 82:679-93. [PMID: 26043180 DOI: 10.1002/mrd.22505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 05/09/2015] [Indexed: 12/24/2022]
Abstract
In mouse oocytes, meiotic induction by pharmacological activation of PRKA (adenosine monophosphate-activated protein kinase; formerly known as AMPK) or by hormones depends on stimulation of fatty acid oxidation (FAO). PRKA stimulates FAO by phosphorylating and inactivating acetyl CoA carboxylase (ACAC; formerly ACC), leading to decreased malonyl CoA levels and augmenting fatty-acid transport into mitochondria. We investigated a role for ACAC inactivation in meiotic resumption by testing the effect of two ACAC inhibitors, CP-640186 and Soraphen A, on mouse oocytes maintained in meiotic arrest in vitro. These inhibitors significantly stimulated the resumption of meiosis in arrested cumulus cell-enclosed oocytes, denuded oocytes, and follicle-enclosed oocytes. This stimulation was accompanied by an increase in FAO. Etomoxir, a malonyl CoA analogue, prevented meiotic resumption as well as the increase in FAO induced by ACAC inhibition. Citrate, an ACAC activator, and CBM-301106, an inhibitor of malonyl CoA decarboxylase, which converts malonyl CoA to acetyl CoA, suppressed both meiotic induction and FAO induced by follicle-stimulating hormone, presumably by maintaining elevated malonyl CoA levels. Mouse oocyte-cumulus cell complexes contain both isoforms of ACAC (ACACA and ACACB); when wild-type and Acacb(-/-) oocytes characteristics were compared, we found that these single-knockout oocytes showed a significantly higher FAO level and a reduced ability to maintain meiotic arrest, resulting in higher rates of germinal vesicle breakdown. Collectively, these data support the model that ACAC inactivation contributes to the maturation-promoting activity of PRKA through stimulation of FAO.
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Affiliation(s)
- Deepa S Valsangkar
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Stephen M Downs
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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54
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Stöckli J, Meoli CC, Hoffman NJ, Fazakerley DJ, Pant H, Cleasby ME, Ma X, Kleinert M, Brandon AE, Lopez JA, Cooney GJ, James DE. The RabGAP TBC1D1 plays a central role in exercise-regulated glucose metabolism in skeletal muscle. Diabetes 2015; 64:1914-22. [PMID: 25576050 DOI: 10.2337/db13-1489] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 12/24/2014] [Indexed: 11/13/2022]
Abstract
Insulin and exercise stimulate glucose uptake into skeletal muscle via different pathways. Both stimuli converge on the translocation of the glucose transporter GLUT4 from intracellular vesicles to the cell surface. Two Rab guanosine triphosphatases-activating proteins (GAPs) have been implicated in this process: AS160 for insulin stimulation and its homolog, TBC1D1, are suggested to regulate exercise-mediated glucose uptake into muscle. TBC1D1 has also been implicated in obesity in humans and mice. We investigated the role of TBC1D1 in glucose metabolism by generating TBC1D1(-/-) mice and analyzing body weight, insulin action, and exercise. TBC1D1(-/-) mice showed normal glucose and insulin tolerance, with no difference in body weight compared with wild-type littermates. GLUT4 protein levels were reduced by ∼40% in white TBC1D1(-/-) muscle, and TBC1D1(-/-) mice showed impaired exercise endurance together with impaired exercise-mediated 2-deoxyglucose uptake into white but not red muscles. These findings indicate that the RabGAP TBC1D1 plays a key role in regulating GLUT4 protein levels and in exercise-mediated glucose uptake in nonoxidative muscle fibers.
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Affiliation(s)
- Jacqueline Stöckli
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia Garvan Institute of Medical Research, Sydney, New South Wales, Australia St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Christopher C Meoli
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Nolan J Hoffman
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Daniel J Fazakerley
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Himani Pant
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Mark E Cleasby
- The Royal Veterinary College, University of London, London, U.K
| | - Xiuquan Ma
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Maximilian Kleinert
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia Molecular Physiology Group, Department of Nutrition, Exercise and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Amanda E Brandon
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Jamie A Lopez
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Gregory J Cooney
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - David E James
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia Garvan Institute of Medical Research, Sydney, New South Wales, Australia School of Medicine, University of Sydney, Sydney, New South Wales, Australia
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55
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Selathurai A, Kowalski GM, Burch ML, Sepulveda P, Risis S, Lee-Young RS, Lamon S, Meikle PJ, Genders AJ, McGee SL, Watt MJ, Russell AP, Frank M, Jackowski S, Febbraio MA, Bruce CR. The CDP-Ethanolamine Pathway Regulates Skeletal Muscle Diacylglycerol Content and Mitochondrial Biogenesis without Altering Insulin Sensitivity. Cell Metab 2015; 21:718-30. [PMID: 25955207 DOI: 10.1016/j.cmet.2015.04.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 02/20/2015] [Accepted: 03/28/2015] [Indexed: 01/20/2023]
Abstract
Accumulation of diacylglycerol (DG) in muscle is thought to cause insulin resistance. DG is a precursor for phospholipids, thus phospholipid synthesis could be involved in regulating muscle DG. Little is known about the interaction between phospholipid and DG in muscle; therefore, we examined whether disrupting muscle phospholipid synthesis, specifically phosphatidylethanolamine (PtdEtn), would influence muscle DG content and insulin sensitivity. Muscle PtdEtn synthesis was disrupted by deleting CTP:phosphoethanolamine cytidylyltransferase (ECT), the rate-limiting enzyme in the CDP-ethanolamine pathway, a major route for PtdEtn production. While PtdEtn was reduced in muscle-specific ECT knockout mice, intramyocellular and membrane-associated DG was markedly increased. Importantly, however, this was not associated with insulin resistance. Unexpectedly, mitochondrial biogenesis and muscle oxidative capacity were increased in muscle-specific ECT knockout mice and were accompanied by enhanced exercise performance. These findings highlight the importance of the CDP-ethanolamine pathway in regulating muscle DG content and challenge the DG-induced insulin resistance hypothesis.
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Affiliation(s)
- Ahrathy Selathurai
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, 3125 VIC, Australia
| | - Greg M Kowalski
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, 3125 VIC, Australia
| | - Micah L Burch
- Department of Physiology, Monash University, Clayton, 3800 VIC, Australia
| | - Patricio Sepulveda
- Department of Physiology, Monash University, Clayton, 3800 VIC, Australia
| | - Steve Risis
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Prahran, 3004 VIC, Australia
| | - Robert S Lee-Young
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Prahran, 3004 VIC, Australia
| | - Severine Lamon
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, 3125 VIC, Australia
| | - Peter J Meikle
- Metabolomics Laboratory, Baker IDI Heart and Diabetes Institute, Prahran, 3004 VIC, Australia
| | - Amanda J Genders
- Metabolic Research Unit, Deakin University, Waurn Ponds, 3216 VIC, Australia
| | - Sean L McGee
- Metabolic Research Unit, Deakin University, Waurn Ponds, 3216 VIC, Australia
| | - Matthew J Watt
- Department of Physiology, Monash University, Clayton, 3800 VIC, Australia
| | - Aaron P Russell
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, 3125 VIC, Australia
| | - Matthew Frank
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Suzanne Jackowski
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Mark A Febbraio
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Prahran, 3004 VIC, Australia
| | - Clinton R Bruce
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, 3125 VIC, Australia.
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Solinas G, Borén J, Dulloo AG. De novo lipogenesis in metabolic homeostasis: More friend than foe? Mol Metab 2015; 4:367-77. [PMID: 25973385 PMCID: PMC4421107 DOI: 10.1016/j.molmet.2015.03.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/06/2015] [Accepted: 03/12/2015] [Indexed: 02/09/2023] Open
Abstract
Background An acute surplus of carbohydrates, and other substrates, can be converted and safely stored as lipids in adipocytes via de novo lipogenesis (DNL). However, in obesity, a condition characterized by chronic positive energy balance, DNL in non-adipose tissues may lead to ectopic lipid accumulation leading to lipotoxicity and metabolic stress. Indeed, DNL is dynamically recruited in liver during the development of fatty liver disease, where DNL is an important source of lipids. Nonetheless, a number of evidences indicates that DNL is an inefficient road for calorie to lipid conversion and that DNL may play an important role in sustaining metabolic homeostasis. Scope of review In this manuscript, we discuss the role of DNL as source of lipids during obesity, the energetic efficiency of this pathway in converting extra calories to lipids, and the function of DNL as a pathway supporting metabolic homeostasis. Major conclusion We conclude that inhibition of DNL in obese subjects, unless coupled with a correction of the chronic positive energy balance, may further promote lipotoxicity and metabolic stress. On the contrary, strategies aimed at specifically activating DNL in adipose tissue could support metabolic homeostasis in obese subjects by a number of mechanisms, which are discussed in this manuscript.
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Affiliation(s)
- Giovanni Solinas
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Jan Borén
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Abdul G Dulloo
- Division of Physiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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57
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Montgomery MK, Turner N. Mitochondrial dysfunction and insulin resistance: an update. Endocr Connect 2015; 4:R1-R15. [PMID: 25385852 PMCID: PMC4261703 DOI: 10.1530/ec-14-0092] [Citation(s) in RCA: 356] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022]
Abstract
Mitochondrial dysfunction has been implicated in the development of insulin resistance (IR); however, a large variety of association and intervention studies as well as genetic manipulations in rodents have reported contrasting results. Indeed, even 39 years after the first publication describing a relationship between IR and diminished mitochondrial function, it is still unclear whether a direct relationship exists, and more importantly if changes in mitochondrial capacity are a cause or consequence of IR. This review will take a journey through the past and summarise the debate about the occurrence of mitochondrial dysfunction and its possible role in causing decreased insulin action in obesity and type 2 diabetes. Evidence is presented from studies in various human populations, as well as rodents with genetic manipulations of pathways known to affect mitochondrial function and insulin action. Finally, we have discussed whether mitochondria are a potential target for the treatment of IR.
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Affiliation(s)
- Magdalene K Montgomery
- Department of PharmacologyUNSW Medicine, School of Medical Sciences, University of New South Wales, Kensington, Sydney, New South Wales 2052, Australia
| | - Nigel Turner
- Department of PharmacologyUNSW Medicine, School of Medical Sciences, University of New South Wales, Kensington, Sydney, New South Wales 2052, Australia
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58
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Healy ME, Chow JD, Byrne FL, Breen DS, Leitinger N, Li C, Lackner C, Caldwell SH, Hoehn KL. Dietary effects on liver tumor burden in mice treated with the hepatocellular carcinogen diethylnitrosamine. J Hepatol 2015; 62:599-606. [PMID: 25450719 PMCID: PMC4336610 DOI: 10.1016/j.jhep.2014.10.024] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 09/22/2014] [Accepted: 10/09/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Mice exposed to the hepatocellular carcinogen diethylnitrosamine at 2 weeks of age have a high risk of developing primary liver tumors later in life. Previous studies have demonstrated that diethylnitrosamine-treated mice have increased tumor burden when fed an obesigenic "Western" diet rich in lard fat and sugar. However, the role of dietary fats vs. sugars in the promotion of liver cancer is poorly understood. The aim of this study was to determine how altering dietary fats vs. sugars affects tumor burden in the diethylnitrosamine model. METHODS C57BL/6N mice were treated with diethylnitrosamine at 2 weeks of age and, from 6 to 32 weeks of age, fed one of five diets that differed in fat and sugar content, including normal chow, ketogenic, and Western diets. RESULTS Mice fed sugar-rich diets had the greatest tumor burden irrespective of dietary fat content. In contrast, mice fed a high-fat low-sugar diet had the least tumor burden despite obesity and glucose intolerance. When evaluated as independent variables, tumor burden was positively correlated with hepatic fat accumulation, postprandial insulin, and liver IL-6, and inversely correlated with serum adiponectin. In contrast, tumor burden did not correlate with adiposity, fasting insulin, or glucose intolerance. Furthermore, mice fed high sugar diets had lower liver expression of p21 and cleaved caspase-3 compared to mice fed low sugar diets. CONCLUSIONS These data indicate that dietary sugar intake contributes to liver tumor burden independent of excess adiposity or insulin resistance in mice treated with diethylnitrosamine.
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Affiliation(s)
- Marin E. Healy
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Jenny D.Y. Chow
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Frances L. Byrne
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - David S. Breen
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Norbert Leitinger
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Chien Li
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Carolin Lackner
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Stephen H. Caldwell
- Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA,Emily Couric Clinical Cancer Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Kyle L. Hoehn
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA,Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA,Emily Couric Clinical Cancer Center, University of Virginia, Charlottesville, VA, 22908, USA,School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia,Contact Information: Correspondence should be addressed to K.L.H. at or . 1-434-284-0462
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59
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Bourbeau MP, Bartberger MD. Recent advances in the development of acetyl-CoA carboxylase (ACC) inhibitors for the treatment of metabolic disease. J Med Chem 2014; 58:525-36. [PMID: 25333641 DOI: 10.1021/jm500695e] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The development of acetyl-CoA carboxylase (ACC) inhibitors for the treatment of metabolic disease has been pursued by the pharmaceutical industry for some time. A number of recent disclosures describing potent ACC inhibitors have been reported by multiple research groups. Unlike many prior publications in this area, more recent publications contain a significant amount of in vivo efficacy data generated by long-term experiments in rodent models of metabolic disease. Additionally, one compound has been advanced to human clinical studies. The results from these studies should allow researchers to better gauge the potential utility of ACC inhibition for the treatment of human disease.
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Affiliation(s)
- Matthew P Bourbeau
- Department of Medicinal Chemistry, and Department of Molecular Structure and Characterization, Amgen, Inc. , 1 Amgen Center Drive, Thousand Oaks, California 91320, United States
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Szkudelski T, Szkudelska K. Resveratrol and diabetes: from animal to human studies. Biochim Biophys Acta Mol Basis Dis 2014; 1852:1145-54. [PMID: 25445538 DOI: 10.1016/j.bbadis.2014.10.013] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 10/10/2014] [Accepted: 10/20/2014] [Indexed: 02/07/2023]
Abstract
Diabetes mellitus is a serious disease affecting about 5% of people worldwide. Diabetes is characterized by hyperglycemia and impairment in insulin secretion and/or action. Moreover, diabetes is associated with metabolic abnormalities and serious complications. Resveratrol is a natural, biologically active polyphenol present in different plant species and known to have numerous health-promoting effects in both animals and humans. Anti-diabetic action of resveratrol has been extensively studied in animal models and in diabetic humans. In animals with experimental diabetes, resveratrol has been demonstrated to induce beneficial effects that ameliorate diabetes. Resveratrol, among others, improves glucose homeostasis, decreases insulin resistance, protects pancreatic β-cells, improves insulin secretion and ameliorates metabolic disorders. Effects induced by resveratrol are strongly related to the capability of this compound to increase expression/activity of AMPK and SIRT1 in various tissues of diabetic subjects. Moreover, anti-oxidant and anti-inflammatory effects of resveratrol were shown to be also involved in its action in diabetic animals. Preliminary clinical trials show that resveratrol is also effective in type 2 diabetic patients. Resveratrol may, among others, improve glycemic control and decrease insulin resistance. These results show that resveratrol holds great potential to treat diabetes and would be useful to support conventional therapy. This article is part of a Special Issue entitled: Resveratrol: Challenges in translating pre-clincial findigns to improved patient outcomes.
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Affiliation(s)
- Tomasz Szkudelski
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland.
| | - Katarzyna Szkudelska
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland
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61
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Mason RR, Mokhtar R, Matzaris M, Selathurai A, Kowalski GM, Mokbel N, Meikle PJ, Bruce CR, Watt MJ. PLIN5 deletion remodels intracellular lipid composition and causes insulin resistance in muscle. Mol Metab 2014; 3:652-63. [PMID: 25161888 PMCID: PMC4142393 DOI: 10.1016/j.molmet.2014.06.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 05/30/2014] [Accepted: 06/05/2014] [Indexed: 01/28/2023] Open
Abstract
Defective control of lipid metabolism leading to lipotoxicity causes insulin resistance in skeletal muscle, a major factor leading to diabetes. Here, we demonstrate that perilipin (PLIN) 5 is required to couple intramyocellular triacylglycerol lipolysis with the metabolic demand for fatty acids. PLIN5 ablation depleted triacylglycerol stores but increased sphingolipids including ceramide, hydroxylceramides and sphingomyelin. We generated perilipin 5 (Plin5)(-/-) mice to determine the functional significance of PLIN5 in metabolic control and insulin action. Loss of PLIN5 had no effect on body weight, feeding or adiposity but increased whole-body carbohydrate oxidation. Plin5 (-/-) mice developed skeletal muscle insulin resistance, which was associated with ceramide accumulation. Liver insulin sensitivity was improved in Plin5 (-/-) mice, indicating tissue-specific effects of PLIN5 on insulin action. We conclude that PLIN5 plays a critical role in coordinating skeletal muscle triacylglycerol metabolism, which impacts sphingolipid metabolism, and is requisite for the maintenance of skeletal muscle insulin action.
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Affiliation(s)
- Rachael R. Mason
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Ruzaidi Mokhtar
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Maria Matzaris
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Ahrathy Selathurai
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Greg M. Kowalski
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Nancy Mokbel
- Garvan Institute of Medical Research, Darlinghurst., New South Wales, 2006, Australia
| | - Peter J. Meikle
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, 3004, Australia
| | - Clinton R. Bruce
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Matthew J. Watt
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, 3800, Australia
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Rodriguez S, Ellis JM, Wolfgang MJ. Chemical-genetic induction of Malonyl-CoA decarboxylase in skeletal muscle. BMC BIOCHEMISTRY 2014; 15:20. [PMID: 25152047 PMCID: PMC4236586 DOI: 10.1186/1471-2091-15-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 08/13/2014] [Indexed: 01/02/2023]
Abstract
Background Defects in skeletal muscle fatty acid oxidation have been implicated in the etiology of insulin resistance. Malonyl-CoA decarboxylase (MCD) has been a target of investigation because it reduces the concentration of malonyl-CoA, a metabolite that inhibits fatty acid oxidation. The in vivo role of muscle MCD expression in the development of insulin resistance remains unclear. Results To determine the role of MCD in skeletal muscle of diet induced obese and insulin resistant mouse models we generated mice expressing a muscle specific transgene for MCD (Tg-fMCDSkel) stabilized posttranslationally by the small molecule, Shield-1. Tg-fMCDSkel and control mice were placed on either a high fat or low fat diet for 3.5 months. Obese and glucose intolerant as well as lean control Tg-fMCDSkel and nontransgenic control mice were treated with Shield-1 and changes in their body weight and insulin sensitivity were determined upon induction of MCD. Inducing MCD activity >5-fold in skeletal muscle over two weeks did not alter body weight or glucose intolerance of obese mice. MCD induction further potentiated the defects in insulin signaling of obese mice. In addition, key enzymes in fatty acid oxidation were suppressed following MCD induction. Conclusion Acute induction of MCD in the skeletal muscle of obese and glucose intolerant mice did not improve body weight and decreased insulin sensitivity compared to obese nontransgenic controls. Induction of MCD in skeletal muscle resulted in a suppression of mitochondrial oxidative genes suggesting a redundant and metabolite driven regulation of gene expression.
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Affiliation(s)
| | | | - Michael J Wolfgang
- Department of Biological Chemistry, Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, 725 N, Wolfe St,, 475 Rangos Building, Baltimore, Maryland 21205, USA.
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O'Neill HM, Lally JS, Galic S, Thomas M, Azizi PD, Fullerton MD, Smith BK, Pulinilkunnil T, Chen Z, Samaan MC, Jorgensen SB, Dyck JRB, Holloway GP, Hawke TJ, van Denderen BJ, Kemp BE, Steinberg GR. AMPK phosphorylation of ACC2 is required for skeletal muscle fatty acid oxidation and insulin sensitivity in mice. Diabetologia 2014; 57:1693-702. [PMID: 24913514 DOI: 10.1007/s00125-014-3273-1] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 05/02/2014] [Indexed: 12/22/2022]
Abstract
AIMS/HYPOTHESIS Obesity is characterised by lipid accumulation in skeletal muscle, which increases the risk of developing insulin resistance and type 2 diabetes. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status and is activated in skeletal muscle by exercise, hormones (leptin, adiponectin, IL-6) and pharmacological agents (5-amino-4-imidazolecarboxamide ribonucleoside [AICAR] and metformin). Phosphorylation of acetyl-CoA carboxylase 2 (ACC2) at S221 (S212 in mice) by AMPK reduces ACC activity and malonyl-CoA content but the importance of the AMPK-ACC2-malonyl-CoA pathway in controlling fatty acid metabolism and insulin sensitivity is not understood; therefore, we characterised Acc2 S212A knock-in (ACC2 KI) mice. METHODS Whole-body and skeletal muscle fatty acid oxidation and insulin sensitivity were assessed in ACC2 KI mice and wild-type littermates. RESULTS ACC2 KI mice were resistant to increases in skeletal muscle fatty acid oxidation elicited by AICAR. These mice had normal adiposity and liver lipids but elevated contents of triacylglycerol and ceramide in skeletal muscle, which were associated with hyperinsulinaemia, glucose intolerance and skeletal muscle insulin resistance. CONCLUSIONS/INTERPRETATION These findings indicate that the phosphorylation of ACC2 S212 is required for the maintenance of skeletal muscle lipid and glucose homeostasis.
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Affiliation(s)
- Hayley M O'Neill
- Division of Endocrinology and Metabolism, Department of Medicine, HSC 4N63, McMaster University, 1280 Main St West, Hamilton, ON, Canada, L8N 3Z5
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Wu LE, Meoli CC, Mangiafico SP, Fazakerley DJ, Cogger VC, Mohamad M, Pant H, Kang MJ, Powter E, Burchfield JG, Xirouchaki CE, Mikolaizak AS, Stöckli J, Kolumam G, van Bruggen N, Gamble JR, Le Couteur DG, Cooney GJ, Andrikopoulos S, James DE. Systemic VEGF-A neutralization ameliorates diet-induced metabolic dysfunction. Diabetes 2014; 63:2656-67. [PMID: 24696450 DOI: 10.2337/db13-1665] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The vascular endothelial growth factor (VEGF) family of cytokines are important regulators of angiogenesis that have emerged as important targets for the treatment of obesity. While serum VEGF levels rise during obesity, recent studies using genetic models provide conflicting evidence as to whether VEGF prevents or accelerates metabolic dysfunction during obesity. In the current study, we sought to identify the effects of VEGF-A neutralization on parameters of glucose metabolism and insulin action in a dietary mouse model of obesity. Within only 72 h of administration of the VEGF-A-neutralizing monoclonal antibody B.20-4.1, we observed almost complete reversal of high-fat diet-induced insulin resistance principally due to improved insulin sensitivity in the liver and in adipose tissue. These effects were independent of changes in whole-body adiposity or insulin signaling. These findings show an important and unexpected role for VEGF in liver insulin resistance, opening up a potentially novel therapeutic avenue for obesity-related metabolic disease.
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Affiliation(s)
- Lindsay E Wu
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, AustraliaLaboratory for Ageing Research, School of Medical Sciences, UNSW Australia, New South Wales, Australia
| | - Christopher C Meoli
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Salvatore P Mangiafico
- Department of Medicine (Austin Health), The University of Melbourne, Heidelberg, Victoria, Australia
| | - Daniel J Fazakerley
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Victoria C Cogger
- Centre for Education and Research on Ageing and ANZAC Medical Research Institute, University of Sydney and Concord Hospital, Concord, New South Wales, Australia
| | - Mashani Mohamad
- Centre for Education and Research on Ageing and ANZAC Medical Research Institute, University of Sydney and Concord Hospital, Concord, New South Wales, AustraliaFaculty of Pharmacy, Universiti Teknologi MARA, Bandar Puncak Alam, Selangor, Malaysia
| | - Himani Pant
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Myung-Jin Kang
- Laboratory for Ageing Research, School of Medical Sciences, UNSW Australia, New South Wales, Australia
| | - Elizabeth Powter
- Centre for the Endothelium, Vascular Biology Program, Centenary Institute, and The University of Sydney, Sydney, Australia
| | - James G Burchfield
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | | | - A Stefanie Mikolaizak
- Falls and Balance Research Group, Neuroscience Research Australia, Sydney, Australia
| | - Jacqueline Stöckli
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Ganesh Kolumam
- Department of Biomedical Imaging, Genentech Inc., San Francisco, CA
| | | | - Jennifer R Gamble
- Centre for the Endothelium, Vascular Biology Program, Centenary Institute, and The University of Sydney, Sydney, Australia
| | - David G Le Couteur
- Centre for Education and Research on Ageing and ANZAC Medical Research Institute, University of Sydney and Concord Hospital, Concord, New South Wales, Australia
| | - Gregory J Cooney
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Sofianos Andrikopoulos
- Department of Medicine (Austin Health), The University of Melbourne, Heidelberg, Victoria, Australia
| | - David E James
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, AustraliaCharles Perkins Centre, School of Molecular Bioscience, The University of Sydney, Sydney, Australia
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Gao AH, Fu YY, Zhang KZ, Zhang M, Jiang HW, Fan LX, Nan FJ, Yuan CG, Li J, Zhou YB, Li JY. Azoxystrobin, a mitochondrial complex III Qo site inhibitor, exerts beneficial metabolic effects in vivo and in vitro. Biochim Biophys Acta Gen Subj 2014; 1840:2212-21. [DOI: 10.1016/j.bbagen.2014.04.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 02/08/2023]
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LaPierre MP, Abraham MA, Filippi BM, Yue JTY, Lam TKT. Glucagon and lipid signaling in the hypothalamus. Mamm Genome 2014; 25:434-41. [DOI: 10.1007/s00335-014-9510-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 03/25/2014] [Indexed: 12/12/2022]
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Kim T, He L, Johnson MS, Li Y, Zeng L, Ding Y, Long Q, Moore JF, Sharer JD, Nagy TR, Young ME, Wood PA, Yang Q. Carnitine Palmitoyltransferase 1b Deficiency Protects Mice from Diet-Induced Insulin Resistance. JOURNAL OF DIABETES & METABOLISM 2014; 5:361. [PMID: 25309812 PMCID: PMC4190034 DOI: 10.4172/2155-6156.1000361] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Carnitine Palmitoyl Transferase 1 (CPT1) is the rate-limiting enzyme governing long-chain fatty acid entry into mitochondria. CPT1 inhibitors have been developed and exhibited beneficial effects against type II diabetes in short-term preclinical animal studies. However, the long-term effects of treatment remain unclear and potential non-specific effects of these CPT1 inhibitors hamper in-depth understanding of the potential molecular mechanisms involved. METHODS We investigated the effects of restricting the activity of the muscle isoform CPT1b in mice using heterozygous CPT1b deficient (Cpt1b+/-) and Wild Type (WT) mice fed with a High Fat Diet (HFD) for 22 weeks. Insulin sensitivity was assessed using Glucose Tolerance Test (GTT), insulin tolerance test and hyperinsulinemic euglycemic clamps. We also examined body weight/composition, tissue and systemic metabolism/energetic status, lipid profile, transcript analysis, and changes in insulin signaling pathways. RESULTS We found that Cpt1b+/- mice were protected from HFD-induced insulin resistance compared to WT littermates. Cpt1b+/- mice exhibited elevated whole body glucose disposal rate and skeletal muscle glucose uptake. Furthermore, Cpt1b+/- skeletal muscle showed diminished ex vivo palmitate oxidative capacity by ~40% and augmented glucose oxidation capacity by ~50% without overt change in whole body energy metabolism. HFD feeding Cpt1b+/- but not WT mice exhibited well-maintained insulin signaling in skeletal muscle, heart, and liver. CONCLUSION The present study on a genetic model of CPT1b restriction supports the concept that partial CPT1b inhibition is a potential therapeutic strategy.
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Affiliation(s)
- Teayoun Kim
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - Lan He
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - Maria S. Johnson
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - Yan Li
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - Ling Zeng
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
- Department of Anatomy, Guangzhou University of Chinese Medicine, Higher Education Mega Center Campus, China
| | - Yishu Ding
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - Qinqiang Long
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - John F. Moore
- Department of Genetics, University of Alabama at Birmingham, USA
| | - Jon D. Sharer
- Department of Genetics, University of Alabama at Birmingham, USA
| | - Tim R. Nagy
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
| | - Martin E. Young
- Department of Medicine, University of Alabama at Birmingham, USA
| | - Philip A. Wood
- Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, USA
| | - Qinglin Yang
- Department of Nutrition Sciences, University of Alabama at Birmingham, USA
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Chow JDY, Lawrence RT, Healy ME, Dominy JE, Liao JA, Breen DS, Byrne FL, Kenwood BM, Lackner C, Okutsu S, Mas VR, Caldwell SH, Tomsig JL, Cooney GJ, Puigserver PB, Turner N, James DE, Villén J, Hoehn KL. Genetic inhibition of hepatic acetyl-CoA carboxylase activity increases liver fat and alters global protein acetylation. Mol Metab 2014; 3:419-31. [PMID: 24944901 PMCID: PMC4060285 DOI: 10.1016/j.molmet.2014.02.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 02/19/2014] [Accepted: 02/21/2014] [Indexed: 02/05/2023] Open
Abstract
Lipid deposition in the liver is associated with metabolic disorders including fatty liver disease, type II diabetes, and hepatocellular cancer. The enzymes acetyl-CoA carboxylase 1 (ACC1) and ACC2 are powerful regulators of hepatic fat storage; therefore, their inhibition is expected to prevent the development of fatty liver. In this study we generated liver-specific ACC1 and ACC2 double knockout (LDKO) mice to determine how the loss of ACC activity affects liver fat metabolism and whole-body physiology. Characterization of LDKO mice revealed unexpected phenotypes of increased hepatic triglyceride and decreased fat oxidation. We also observed that chronic ACC inhibition led to hyper-acetylation of proteins in the extra-mitochondrial space. In sum, these data reveal the existence of a compensatory pathway that protects hepatic fat stores when ACC enzymes are inhibited. Furthermore, we identified an important role for ACC enzymes in the regulation of protein acetylation in the extra-mitochondrial space.
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Affiliation(s)
- Jenny D Y Chow
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Robert T Lawrence
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Marin E Healy
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - John E Dominy
- Department of Cancer Biology, Dana-Faber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA ; Department of Cell Biology, Dana-Faber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jason A Liao
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - David S Breen
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Frances L Byrne
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Brandon M Kenwood
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Carolin Lackner
- Institute of Pathology, Medical University Graz, Graz, Austria
| | - Saeko Okutsu
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Valeria R Mas
- Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Stephen H Caldwell
- Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Jose L Tomsig
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Gregory J Cooney
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - Pere B Puigserver
- Department of Cancer Biology, Dana-Faber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA ; Department of Cell Biology, Dana-Faber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Nigel Turner
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - David E James
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Kyle L Hoehn
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA ; Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA ; School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
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Guo S. Insulin signaling, resistance, and the metabolic syndrome: insights from mouse models into disease mechanisms. J Endocrinol 2014; 220:T1-T23. [PMID: 24281010 PMCID: PMC4087161 DOI: 10.1530/joe-13-0327] [Citation(s) in RCA: 326] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Insulin resistance is a major underlying mechanism responsible for the 'metabolic syndrome', which is also known as insulin resistance syndrome. The incidence of the metabolic syndrome is increasing at an alarming rate, becoming a major public and clinical problem worldwide. The metabolic syndrome is represented by a group of interrelated disorders, including obesity, hyperglycemia, hyperlipidemia, and hypertension. It is also a significant risk factor for cardiovascular disease and increased morbidity and mortality. Animal studies have demonstrated that insulin and its signaling cascade normally control cell growth, metabolism, and survival through the activation of MAPKs and activation of phosphatidylinositide-3-kinase (PI3K), in which the activation of PI3K associated with insulin receptor substrate 1 (IRS1) and IRS2 and subsequent Akt→Foxo1 phosphorylation cascade has a central role in the control of nutrient homeostasis and organ survival. The inactivation of Akt and activation of Foxo1, through the suppression IRS1 and IRS2 in different organs following hyperinsulinemia, metabolic inflammation, and overnutrition, may act as the underlying mechanisms for the metabolic syndrome in humans. Targeting the IRS→Akt→Foxo1 signaling cascade will probably provide a strategy for therapeutic intervention in the treatment of type 2 diabetes and its complications. This review discusses the basis of insulin signaling, insulin resistance in different mouse models, and how a deficiency of insulin signaling components in different organs contributes to the features of the metabolic syndrome. Emphasis is placed on the role of IRS1, IRS2, and associated signaling pathways that are coupled to Akt and the forkhead/winged helix transcription factor Foxo1.
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Affiliation(s)
- Shaodong Guo
- Division of Molecular Cardiology, Department of Medicine, College of Medicine, Texas A&M University Health Science Center, Scott & White, Central Texas Veterans Health Care System, 1901 South 1st Street, Bldg. 205, Temple, Texas 76504, USA
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Turner N, Cooney GJ, Kraegen EW, Bruce CR. Fatty acid metabolism, energy expenditure and insulin resistance in muscle. J Endocrinol 2014; 220:T61-79. [PMID: 24323910 DOI: 10.1530/joe-13-0397] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fatty acids (FAs) are essential elements of all cells and have significant roles as energy substrates, components of cellular structure and signalling molecules. The storage of excess energy intake as fat in adipose tissue is an evolutionary advantage aimed at protecting against starvation, but in much of today's world, humans are faced with an unlimited availability of food, and the excessive accumulation of fat is now a major risk for human health, especially the development of type 2 diabetes (T2D). Since the first recognition of the association between fat accumulation, reduced insulin action and increased risk of T2D, several mechanisms have been proposed to link excess FA availability to reduced insulin action, with some of them being competing or contradictory. This review summarises the evidence for these mechanisms in the context of excess dietary FAs generating insulin resistance in muscle, the major tissue involved in insulin-stimulated disposal of blood glucose. It also outlines potential problems with models and measurements that may hinder as well as help improve our understanding of the links between FAs and insulin action.
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Affiliation(s)
- Nigel Turner
- Department of Pharmacology School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia Diabetes and Obesity Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales 2010, Australia St Vincent's Clinical School, University of New South Wales, Sydney, New South Wales, Australia Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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Bourbeau MP, Siegmund A, Allen JG, Shu H, Fotsch C, Bartberger MD, Kim KW, Komorowski R, Graham M, Busby J, Wang M, Meyer J, Xu Y, Salyers K, Fielden M, Véniant MM, Gu W. Piperazine oxadiazole inhibitors of acetyl-CoA carboxylase. J Med Chem 2013; 56:10132-41. [PMID: 24294923 DOI: 10.1021/jm401601s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acetyl-CoA carboxylase (ACC) is a target of interest for the treatment of metabolic syndrome. Starting from a biphenyloxadiazole screening hit, a series of piperazine oxadiazole ACC inhibitors was developed. Initial pharmacokinetic liabilities of the piperazine oxadiazoles were overcome by blocking predicted sites of metabolism, resulting in compounds with suitable properties for further in vivo studies. Compound 26 was shown to inhibit malonyl-CoA production in an in vivo pharmacodynamic assay and was advanced to a long-term efficacy study. Prolonged dosing with compound 26 resulted in impaired glucose tolerance in diet-induced obese (DIO) C57BL6 mice, an unexpected finding.
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Affiliation(s)
- Matthew P Bourbeau
- Therapeutic Discovery, ‡Metabolic Diseases Research, §Pharmacokinetics/Drug Metabolism, and ∥Comparative Biology & Safety Sciences, Amgen Inc. , 1 Amgen Center Dr, Thousand Oaks, California 91320, United States
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Fullerton MD, Galic S, Marcinko K, Sikkema S, Pulinilkunnil T, Chen Z, O’Neill HM, Ford RJ, Palanivel R, O’Brien M, Hardie DG, Macaulay SL, Schertzer JD, Dyck JRB, van Denderen BJ, Kemp BE, Steinberg GR. Single phosphorylation sites in Acc1 and Acc2 regulate lipid homeostasis and the insulin-sensitizing effects of metformin. Nat Med 2013; 19:1649-54. [PMID: 24185692 PMCID: PMC4965268 DOI: 10.1038/nm.3372] [Citation(s) in RCA: 590] [Impact Index Per Article: 53.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 09/11/2013] [Indexed: 12/15/2022]
Abstract
The obesity epidemic has led to an increased incidence of nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes. AMP-activated protein kinase (Ampk) regulates energy homeostasis and is activated by cellular stress, hormones and the widely prescribed type 2 diabetes drug metformin. Ampk phosphorylates mouse acetyl-CoA carboxylase 1 (Acc1; refs. 3,4) at Ser79 and Acc2 at Ser212, inhibiting the conversion of acetyl-CoA to malonyl-CoA. The latter metabolite is a precursor in fatty acid synthesis and an allosteric inhibitor of fatty acid transport into mitochondria for oxidation. To test the physiological impact of these phosphorylation events, we generated mice with alanine knock-in mutations in both Acc1 (at Ser79) and Acc2 (at Ser212) (Acc double knock-in, AccDKI). Compared to wild-type mice, these mice have elevated lipogenesis and lower fatty acid oxidation, which contribute to the progression of insulin resistance, glucose intolerance and NAFLD, but not obesity. Notably, AccDKI mice made obese by high-fat feeding are refractory to the lipid-lowering and insulin-sensitizing effects of metformin. These findings establish that inhibitory phosphorylation of Acc by Ampk is essential for the control of lipid metabolism and, in the setting of obesity, for metformin-induced improvements in insulin action.
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Affiliation(s)
- Morgan D. Fullerton
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
| | - Sandra Galic
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
| | - Katarina Marcinko
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
| | - Sarah Sikkema
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
| | - Thomas Pulinilkunnil
- Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, T6G 2S2 Edmonton, Alberta, Canada
| | - Zhi–Ping Chen
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
| | - Hayley M. O’Neill
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
| | - Rebecca J. Ford
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
| | - Rengasamy Palanivel
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
| | - Matthew O’Brien
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
| | - D. Grahame Hardie
- Division of Cell Signaling & Immunology, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK
| | - S. Lance Macaulay
- CSIRO Preventative Health Flagship, Materials Science and Engineering, Parkville, Vic 3052, Australia
| | - Jonathan D. Schertzer
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
| | - Jason R. B. Dyck
- Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, T6G 2S2 Edmonton, Alberta, Canada
| | - Bryce J. van Denderen
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
| | - Bruce E. Kemp
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
| | - Gregory R. Steinberg
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main St. W., Hamilton, Ontario, Canada L8N 3Z5
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Vic 3065, Australia
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Opening of the mitochondrial permeability transition pore links mitochondrial dysfunction to insulin resistance in skeletal muscle. Mol Metab 2013; 3:124-34. [PMID: 24634818 DOI: 10.1016/j.molmet.2013.11.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 11/14/2013] [Indexed: 12/14/2022] Open
Abstract
Insulin resistance is associated with mitochondrial dysfunction, but the mechanism by which mitochondria inhibit insulin-stimulated glucose uptake into the cytoplasm is unclear. The mitochondrial permeability transition pore (mPTP) is a protein complex that facilitates the exchange of molecules between the mitochondrial matrix and cytoplasm, and opening of the mPTP occurs in response to physiological stressors that are associated with insulin resistance. In this study, we investigated whether mPTP opening provides a link between mitochondrial dysfunction and insulin resistance by inhibiting the mPTP gatekeeper protein cyclophilin D (CypD) in vivo and in vitro. Mice lacking CypD were protected from high fat diet-induced glucose intolerance due to increased glucose uptake in skeletal muscle. The mitochondria in CypD knockout muscle were resistant to diet-induced swelling and had improved calcium retention capacity compared to controls; however, no changes were observed in muscle oxidative damage, insulin signaling, lipotoxic lipid accumulation or mitochondrial bioenergetics. In vitro, we tested 4 models of insulin resistance that are linked to mitochondrial dysfunction in cultured skeletal muscle cells including antimycin A, C2-ceramide, ferutinin, and palmitate. In all models, we observed that pharmacological inhibition of mPTP opening with the CypD inhibitor cyclosporin A was sufficient to prevent insulin resistance at the level of insulin-stimulated GLUT4 translocation to the plasma membrane. The protective effects of mPTP inhibition on insulin sensitivity were associated with improved mitochondrial calcium retention capacity but did not involve changes in insulin signaling both in vitro and in vivo. In sum, these data place the mPTP at a critical intersection between alterations in mitochondrial function and insulin resistance in skeletal muscle.
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Key Words
- ANT, adenine nucleotide translocator
- BKA, bongkrekic acid
- CSA, cyclosporin A
- CYPD, cyclophilin D
- Cyclophilin D
- DAG, diacylglycerol
- ETC, electron transport chain
- FFA, free fatty acid
- Glucose
- HFD, high fat diet
- HK2, hexokinase 2
- Insulin resistance
- KO, knockout
- LFD, low fat diet
- MCAD, medium chain acyl-CoA dehydrogenase
- MHC, myosin heavy chain
- MIRKO, muscle insulin receptor knockout
- MPTP, mitochondrial permeability transition pore
- Mitochondrial dysfunction
- Mitochondrial permeability transition pore
- MnSOD, mitochondrial manganese superoxide dismutase
- O2•, superoxide
- OXPHOS, oxidative phosphorylation
- PDH, pyruvate dehydrogenase
- PDHa, active PDH
- PDHt, total PDH
- PM, plasma membrane
- Rg′, rate of glucose transport
- Skeletal muscle
- TBARS, thiobarbituric acid reactive substances
- TEM, transmission electron microscopy
- VDAC, voltage-dependent anion channel
- WT, wild type
- [3H]-2-DOG, [3H]-2-deoxyglucose
- β-HAD, β-hydroxyacyl-CoA dehydrogenase
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74
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Abstract
The liver plays a unique, central role in regulating lipid metabolism. In addition to influencing hepatic function and disease, changes in specific pathways of fatty acid (FA) metabolism have wide-ranging effects on the metabolism of other nutrients, extra-hepatic physiology, and the development of metabolic diseases. The high prevalence of nonalcoholic fatty liver disease (NAFLD) has led to increased efforts to characterize the underlying biology of hepatic energy metabolism and FA trafficking that leads to disease development. Recent advances have uncovered novel roles of metabolic pathways and specific enzymes in generating lipids important for cellular processes such as signal transduction and transcriptional activation. These studies have also advanced our understanding of key branch points involving FA partitioning between metabolic pathways and have identified new roles for lipid droplets in these events. This review covers recent advances in our understanding of FA trafficking and its regulation. An emphasis will be placed on branch points in these pathways and how alterations in FA trafficking contribute to NAFLD and related comorbidities.
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75
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Ho L, Titus AS, Banerjee KK, George S, Lin W, Deota S, Saha AK, Nakamura K, Gut P, Verdin E, Kolthur-Seetharam U. SIRT4 regulates ATP homeostasis and mediates a retrograde signaling via AMPK. Aging (Albany NY) 2013; 5:835-49. [PMID: 24296486 PMCID: PMC3868726 DOI: 10.18632/aging.100616] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
Abstract
Efficient coupling of cellular energy production to metabolic demand is crucial to maintain organismal homeostasis. Here, we report that the mitochondrial Sirtuin Sirt4 regulates mitochondrial ATP homeostasis. We find that Sirt4 affects mitochondrial uncoupling via the adenine nucleotide translocator 2 (ANT2). Loss of Sirt4 expression leads to decreased cellular ATP levelsin vitro and in vivo while Sirt4 overexpression is associated with increased ATP levels. Further, we provide evidence that lack of Sirt4 activates a retrograde signaling response from the mitochondria to the nucleus that includes AMPK, PGC1α, key regulators of β-oxidation such as Acetyl-CoA carboxylase, and components of the mitochondrial respiratory machinery. This study highlights the ability of Sirt4 to regulate ATP levels via ANT2 and a feedback loop involving AMPK.
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Affiliation(s)
- Linh Ho
- The Gladstone Institute of Virology and Immunology, San Francisco, CA 94158, USA
| | - Allen Sam Titus
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, India
| | - Kushal Kr Banerjee
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, India
| | - Suji George
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, India
| | - Wei Lin
- The Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Shaunak Deota
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, India
| | | | - Ken Nakamura
- The Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, CA 94158, USA
| | - Philipp Gut
- The Gladstone Institute of Virology and Immunology, San Francisco, CA 94158, USA
| | - Eric Verdin
- The Gladstone Institute of Virology and Immunology, San Francisco, CA 94158, USA
- Department of Medicine, University of California, San Francisco, CA 94158, USA
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76
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Bays HE, Toth PP, Kris-Etherton PM, Abate N, Aronne LJ, Brown WV, Gonzalez-Campoy JM, Jones SR, Kumar R, La Forge R, Samuel VT. Obesity, adiposity, and dyslipidemia: a consensus statement from the National Lipid Association. J Clin Lipidol 2013; 7:304-83. [PMID: 23890517 DOI: 10.1016/j.jacl.2013.04.001] [Citation(s) in RCA: 295] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 01/04/2023]
Abstract
The term "fat" may refer to lipids as well as the cells and tissue that store lipid (ie, adipocytes and adipose tissue). "Lipid" is derived from "lipos," which refers to animal fat or vegetable oil. Adiposity refers to body fat and is derived from "adipo," referring to fat. Adipocytes and adipose tissue store the greatest amount of body lipids, including triglycerides and free cholesterol. Adipocytes and adipose tissue are active from an endocrine and immune standpoint. Adipocyte hypertrophy and excessive adipose tissue accumulation can promote pathogenic adipocyte and adipose tissue effects (adiposopathy), resulting in abnormal levels of circulating lipids, with dyslipidemia being a major atherosclerotic coronary heart disease risk factor. It is therefore incumbent upon lipidologists to be among the most knowledgeable in the understanding of the relationship between excessive body fat and dyslipidemia. On September 16, 2012, the National Lipid Association held a Consensus Conference with the goal of better defining the effect of adiposity on lipoproteins, how the pathos of excessive body fat (adiposopathy) contributes to dyslipidemia, and how therapies such as appropriate nutrition, increased physical activity, weight-management drugs, and bariatric surgery might be expected to impact dyslipidemia. It is hoped that the information derived from these proceedings will promote a greater appreciation among clinicians of the impact of excess adiposity and its treatment on dyslipidemia and prompt more research on the effects of interventions for improving dyslipidemia and reducing cardiovascular disease risk in overweight and obese patients.
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Affiliation(s)
- Harold E Bays
- Louisville Metabolic and Atherosclerosis Research Center, 3288 Illinois Avenue, Louisville, KY 40213, USA.
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77
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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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78
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Arch JRS, Trayhurn P. Detection of thermogenesis in rodents in response to anti-obesity drugs and genetic modification. Front Physiol 2013; 4:64. [PMID: 23580228 PMCID: PMC3619105 DOI: 10.3389/fphys.2013.00064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/16/2013] [Indexed: 11/22/2022] Open
Abstract
Many compounds and genetic manipulations are claimed to confer resistance to obesity in rodents by raising energy expenditure. Examples taken from recent and older literature, demonstrate that such claims are often based on measurements of energy expenditure after body composition has changed, and depend on comparisons of energy expenditure divided by body weight. This is misleading because white adipose tissue has less influence than lean tissue on energy expenditure. Application of this approach to human data would suggest that human obesity is usually due to a low metabolic rate, which is not an accepted view. Increased energy expenditure per animal is a surer way of demonstrating thermogenesis, but even then it is important to know whether this is due to altered body composition (repartitioning), or increased locomotor activity rather than thermogenesis per se. Regression analysis offers other approaches. The thermogenic response to some compounds has a rapid onset and so cannot be due to altered body composition. These compounds usually mimic or activate the sympathetic nervous system. Thermogenesis occurs in, but may not be confined to, brown adipose tissue. It should not be assumed that weight loss in response to these treatments is due to thermogenesis unless there is a sustained increase in 24-h energy expenditure. Thyroid hormones and fibroblast growth factor 21 also raise energy expenditure before they affect body composition. Some treatments and genetic modifications alter the diurnal rhythm of energy expenditure. It is important to establish whether this is due to altered locomotor activity or efficiency of locomotion. There are no good examples of compounds that do not affect short-term energy expenditure but have a delayed effect. How and under what conditions a genetic modification or compound increases energy expenditure influences the decision on whether to seek drugs for the target or take a candidate drug into clinical studies.
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79
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Abstract
The specific cellular underpinnings or mechanisms of insulin resistance (IR) are not clear. Here I present evidence to support a causal association between mitochondrial energetics and IR. A large body of literature indicates that mitochondrial capacity for oxidative metabolism is lower in human obesity and type 2 diabetes. Whether or not mitochondria play a causal role in IR is hotly debated. First, IR can be caused by many factors, many of which may or may not involve mitochondria. These include lipid overload, oxidative stress, and inflammation. Thus the first tenet of an argument supporting a role for mitochondria in IR is that mitochondria derangements can cause IR, but IR does not have to involve mitochondria. The second tenet of this argument is that animal models in which oxidative metabolism are completely abolished are not always physiologically or pathologically relevant to human IR, in which small metabolic perturbations can have profound effects over a prolonged period. Lastly, mitochondria are complex organelles, with diverse functions, including links with cell signaling, oxidative stress, and inflammation, which in turn can be connected with IR. In summary, mitochondrial "deficiency" is not merely a reduced energy generation or low fatty acid oxidation; this concept should be expanded to numerous additional important functions, many of which can cause IR if perturbed.
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Affiliation(s)
- Bret H Goodpaster
- Division of Endocrinology and Metabolism, Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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80
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Keung W, Ussher JR, Jaswal JS, Raubenheimer M, Lam VH, Wagg CS, Lopaschuk GD. Inhibition of carnitine palmitoyltransferase-1 activity alleviates insulin resistance in diet-induced obese mice. Diabetes 2013; 62:711-20. [PMID: 23139350 PMCID: PMC3581198 DOI: 10.2337/db12-0259] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Impaired skeletal muscle fatty acid oxidation has been suggested to contribute to insulin resistance and glucose intolerance. However, increasing muscle fatty acid oxidation may cause a reciprocal decrease in glucose oxidation, which might impair insulin sensitivity and glucose tolerance. We therefore investigated what effect inhibition of mitochondrial fatty acid uptake has on whole-body glucose tolerance and insulin sensitivity in obese insulin-resistant mice. C57BL/6 mice were fed a high-fat diet (60% calories from fat) for 12 weeks to develop insulin resistance. Subsequent treatment of mice for 4 weeks with the carnitine palmitoyltransferase-1 inhibitor, oxfenicine (150 mg/kg i.p. daily), resulted in improved whole-body glucose tolerance and insulin sensitivity. Exercise capacity was increased in oxfenicine-treated mice, which was accompanied by an increased respiratory exchange ratio. In the gastrocnemius muscle, oxfenicine increased pyruvate dehydrogenase activity, membrane GLUT4 content, and insulin-stimulated Akt phosphorylation. Intramyocellular levels of lipid intermediates, including ceramide, long-chain acyl CoA, and diacylglycerol, were also decreased. Our results demonstrate that inhibition of mitochondrial fatty acid uptake improves insulin sensitivity in diet-induced obese mice. This is associated with increased carbohydrate utilization and improved insulin signaling in the skeletal muscle, suggestive of an operating Randle Cycle in muscle.
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81
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Ma L, Murea M, Snipes JA, Marinelarena A, Krüger J, Hicks PJ, Langberg KA, Bostrom MA, Cooke JN, Suzuki D, Babazono T, Uzu T, Tang SCW, Mondal AK, Sharma NK, Kobes S, Antinozzi PA, Davis M, Das SK, Rasouli N, Kern PA, Shores NJ, Rudel LL, Blüher M, Stumvoll M, Bowden DW, Maeda S, Parks JS, Kovacs P, Hanson RL, Baier LJ, Elbein SC, Freedman BI. An ACACB variant implicated in diabetic nephropathy associates with body mass index and gene expression in obese subjects. PLoS One 2013; 8:e56193. [PMID: 23460794 PMCID: PMC3584087 DOI: 10.1371/journal.pone.0056193] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 01/07/2013] [Indexed: 02/04/2023] Open
Abstract
Acetyl coenzyme A carboxylase B gene (ACACB) single nucleotide polymorphism (SNP) rs2268388 is reproducibly associated with type 2 diabetes (T2DM)-associated nephropathy (DN). ACACB knock-out mice are also protected from obesity. This study assessed relationships between rs2268388, body mass index (BMI) and gene expression in multiple populations, with and without T2DM. Among subjects without T2DM, rs2268388 DN risk allele (T) associated with higher BMI in Pima Indian children (n = 2021; p-additive = 0.029) and African Americans (AAs) (n = 177; p-additive = 0.05), with a trend in European Americans (EAs) (n = 512; p-additive = 0.09), but not Germans (n = 858; p-additive = 0.765). Association with BMI was seen in a meta-analysis including all non-T2DM subjects (n = 3568; p-additive = 0.02). Among subjects with T2DM, rs2268388 was not associated with BMI in Japanese (n = 2912) or EAs (n = 1149); however, the T allele associated with higher BMI in the subset with BMI≥30 kg/m(2) (n = 568 EAs; p-additive = 0.049, n = 196 Japanese; p-additive = 0.049). Association with BMI was strengthened in a T2DM meta-analysis that included an additional 756 AAs (p-additive = 0.080) and 48 Hong Kong Chinese (p-additive = 0.81) with BMI≥30 kg/m(2) (n = 1575; p-additive = 0.0033). The effect of rs2268388 on gene expression revealed that the T risk allele associated with higher ACACB messenger levels in adipose tissue (41 EAs and 20 AAs with BMI>30 kg/m(2); p-additive = 0.018) and ACACB protein levels in the liver tissue (mixed model p-additive = 0.03, in 25 EA bariatric surgery patients with BMI>30 kg/m(2) for 75 exams). The T allele also associated with higher hepatic triglyceride levels. These data support a role for ACACB in obesity and potential roles for altered lipid metabolism in susceptibility to DN.
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Affiliation(s)
- Lijun Ma
- Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America.
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82
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Ceddia RB. The role of AMP-activated protein kinase in regulating white adipose tissue metabolism. Mol Cell Endocrinol 2013; 366:194-203. [PMID: 22750051 DOI: 10.1016/j.mce.2012.06.014] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 03/16/2012] [Accepted: 06/21/2012] [Indexed: 01/19/2023]
Abstract
AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that plays a major role in the maintenance of energy homeostasis in various organs and tissues. When activated, AMPK can induce substrate catabolism and shut down energy-consuming anabolic pathways to increase intracellular ATP availability. Even though most of these effects have been described in muscle and liver, several studies have provided compelling evidence that AMPK also plays an important role in the regulation of white adipose tissue (WAT) glucose and lipid metabolism. In fact, the effects of acute and chronic AMPK activation in the WAT induce profound changes in adiposity with important implications for the treatment of obesity and its related metabolic disorders. This review discusses the role of AMPK in the regulation of white adipocyte metabolism with respect to energy storage and release, gene expression, mitochondrial biogenesis, oxidative capacity, cell differentiation, and the potential impact on whole-body adiposity and energy homeostasis.
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Affiliation(s)
- R B Ceddia
- School of Kinesiology and Health Science, York University, Toronto, ON, Canada.
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83
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O'Neill HM, Holloway GP, Steinberg GR. AMPK regulation of fatty acid metabolism and mitochondrial biogenesis: implications for obesity. Mol Cell Endocrinol 2013; 366:135-51. [PMID: 22750049 DOI: 10.1016/j.mce.2012.06.019] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 03/13/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
Abstract
Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a major site for glucose and lipid oxidation. Obesity and type 2 diabetes are causally linked through their association with skeletal muscle insulin resistance, while conversely exercise is known to improve whole body glucose homeostasis simultaneously with muscle insulin sensitivity. Exercise activates skeletal muscle AMP-activated protein kinase (AMPK). AMPK plays a role in regulating exercise capacity, skeletal muscle mitochondrial content and contraction-stimulated glucose uptake. Skeletal muscle AMPK is also thought to be important for regulating fatty acid metabolism; however, direct genetic evidence in this area is currently lacking. This review will discuss the current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise, and highlight the potential implications in the development of insulin resistance.
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Affiliation(s)
- Hayley M O'Neill
- University of Melbourne, Department of Medicine, St. Vincent's Institute of Medical Research, Melbourne, Victoria, Australia.
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84
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Assini JM, Mulvihill EE, Sutherland BG, Telford DE, Sawyez CG, Felder SL, Chhoker S, Edwards JY, Gros R, Huff MW. Naringenin prevents cholesterol-induced systemic inflammation, metabolic dysregulation, and atherosclerosis in Ldlr⁻/⁻ mice. J Lipid Res 2012; 54:711-724. [PMID: 23269394 DOI: 10.1194/jlr.m032631] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Obesity-associated chronic inflammation contributes to metabolic dysfunction and propagates atherosclerosis. Recent evidence suggests that increased dietary cholesterol exacerbates inflammation in adipose tissue and liver, contributing to the proatherogenic milieu. The ability of the citrus flavonoid naringenin to prevent these cholesterol-induced perturbations is unknown. To assess the ability of naringenin to prevent the amplified inflammatory response and atherosclerosis induced by dietary cholesterol, male Ldlr⁻/⁻ mice were fed either a cholesterol-enriched high-fat or low-fat diet supplemented with 3% naringenin for 12 weeks. Naringenin, through induction of hepatic fatty acid (FA) oxidation and attenuation of FA synthesis, prevented hepatic steatosis, hepatic VLDL overproduction, and hyperlipidemia induced by both cholesterol-rich diets. Naringenin attenuated hepatic macrophage infiltration and inflammation stimulated by dietary cholesterol. Insulin resistance, adipose tissue expansion, and inflammation were alleviated by naringenin. Naringenin attenuated the cholesterol-induced formation of both foam cells and expression of inflammatory markers in peritoneal macrophages. Naringenin significantly decreased atherosclerosis and inhibited the formation of complex lesions, which was associated with normalized aortic lipids and a reversal of aortic inflammation. We demonstrate that in mice fed cholesterol-enriched diets, naringenin attenuates peripheral and systemic inflammation, leading to protection from atherosclerosis. These studies offer a therapeutically relevant alternative for the prevention of cholesterol-induced metabolic dysregulation.
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Affiliation(s)
- Julia M Assini
- Vascular Biology, Robarts Research Institute; Department of Biochemistry
| | - Erin E Mulvihill
- Vascular Biology, Robarts Research Institute; Department of Biochemistry
| | | | - Dawn E Telford
- Vascular Biology, Robarts Research Institute; Department of Medicine
| | - Cynthia G Sawyez
- Vascular Biology, Robarts Research Institute; Department of Medicine
| | - Sarah L Felder
- Vascular Biology, Robarts Research Institute; Department of Biochemistry
| | - Sanjiv Chhoker
- Vascular Biology, Robarts Research Institute; Department of Biochemistry
| | - Jane Y Edwards
- Vascular Biology, Robarts Research Institute; Department of Medicine
| | - Robert Gros
- Vascular Biology, Robarts Research Institute; Department of Medicine; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Murray W Huff
- Vascular Biology, Robarts Research Institute; Department of Biochemistry; Department of Medicine
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85
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Fargali S, Scherer T, Shin AC, Sadahiro M, Buettner C, Salton SR. Germline ablation of VGF increases lipolysis in white adipose tissue. J Endocrinol 2012; 215:313-22. [PMID: 22942234 PMCID: PMC3488863 DOI: 10.1530/joe-12-0172] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Targeted deletion of VGF, a neuronal and endocrine secreted protein and neuropeptide precursor, produces a lean, hypermetabolic mouse that is resistant to diet-, lesion-, and genetically induced obesity and diabetes. We hypothesized that increased sympathetic nervous system activity in Vgf-/Vgf- knockout mice is responsible for increased energy expenditure and decreased fat storage and that increased β-adrenergic receptor stimulation induces lipolysis in white adipose tissue (WAT) of Vgf-/Vgf- mice. We found that fat mass was markedly reduced in Vgf-/Vgf- mice. Within knockout WAT, phosphorylation of protein kinase A substrate increased in males and females, phosphorylation of hormone-sensitive lipase (HSL) (ser563) increased in females, and levels of adipose triglyceride lipase, comparative gene identification-58, and phospho-perilipin were higher in male Vgf-/Vgf- WAT compared with wild-type, consistent with increased lipolysis. The phosphorylation of AMP-activated protein kinase (AMPK) (Thr172) and levels of the AMPK kinase, transforming growth factor β-activated kinase 1, were decreased. This was associated with a decrease in HSL ser565 phosphorylation, the site phosphorylated by AMPK, in both male and female Vgf-/Vgf- WAT. No significant differences in phosphorylation of CREB or the p42/44 MAPK were noted. Despite this evidence supporting increased cAMP signaling and lipolysis, lipogenesis as assessed by fatty acid synthase protein expression and phosphorylated acetyl-CoA carboxylase was not decreased. Our data suggest that the VGF precursor or selected VGF-derived peptides dampen sympathetic outflow pathway activity to WAT to regulate fat storage and lipolysis.
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Affiliation(s)
- Samira Fargali
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
| | - Thomas Scherer
- Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
| | - Andrew C. Shin
- Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
| | - Masato Sadahiro
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
| | - Christoph Buettner
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
- Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
| | - Stephen R. Salton
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
- Department of Geriatrics, Mount Sinai School of Medicine, New York, NY, USA
- Corresponding author: Dr. Stephen R. Salton, Department of Neuroscience, Box 1065, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York NY 10029 USA, Tel: 1-212-659-5901, Fax: 1-212-996-9785,
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86
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Structure and function of biotin-dependent carboxylases. Cell Mol Life Sci 2012; 70:863-91. [PMID: 22869039 DOI: 10.1007/s00018-012-1096-0] [Citation(s) in RCA: 258] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/07/2012] [Accepted: 07/09/2012] [Indexed: 12/14/2022]
Abstract
Biotin-dependent carboxylases include acetyl-CoA carboxylase (ACC), propionyl-CoA carboxylase (PCC), 3-methylcrotonyl-CoA carboxylase (MCC), geranyl-CoA carboxylase, pyruvate carboxylase (PC), and urea carboxylase (UC). They contain biotin carboxylase (BC), carboxyltransferase (CT), and biotin-carboxyl carrier protein components. These enzymes are widely distributed in nature and have important functions in fatty acid metabolism, amino acid metabolism, carbohydrate metabolism, polyketide biosynthesis, urea utilization, and other cellular processes. ACCs are also attractive targets for drug discovery against type 2 diabetes, obesity, cancer, microbial infections, and other diseases, and the plastid ACC of grasses is the target of action of three classes of commercial herbicides. Deficiencies in the activities of PCC, MCC, or PC are linked to serious diseases in humans. Our understanding of these enzymes has been greatly enhanced over the past few years by the crystal structures of the holoenzymes of PCC, MCC, PC, and UC. The structures reveal unanticipated features in the architectures of the holoenzymes, including the presence of previously unrecognized domains, and provide a molecular basis for understanding their catalytic mechanism as well as the large collection of disease-causing mutations in PCC, MCC, and PC. This review will summarize the recent advances in our knowledge on the structure and function of these important metabolic enzymes.
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87
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Hoehn KL, Turner N, Cooney GJ, James DE. Phenotypic discrepancies in acetyl-CoA carboxylase 2-deficient mice. J Biol Chem 2012; 287:15801; author reply 15802. [PMID: 22563100 DOI: 10.1074/jbc.o112.356915] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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88
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Glund S, Schoelch C, Thomas L, Niessen HG, Stiller D, Roth GJ, Neubauer H. Inhibition of acetyl-CoA carboxylase 2 enhances skeletal muscle fatty acid oxidation and improves whole-body glucose homeostasis in db/db mice. Diabetologia 2012; 55:2044-53. [PMID: 22532389 DOI: 10.1007/s00125-012-2554-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 03/12/2012] [Indexed: 01/13/2023]
Abstract
AIMS/HYPOTHESIS Excessive ectopic lipid deposition contributes to impaired insulin action in peripheral tissues and is considered an important link between obesity and type 2 diabetes mellitus. Acetyl-CoA carboxylase 2 (ACC2) is a key regulatory enzyme controlling skeletal muscle mitochondrial fatty acid oxidation; inhibition of ACC2 results in enhanced oxidation of lipids. Several mouse models lacking functional ACC2 have been reported in the literature. However, the phenotypes of the different models are inconclusive with respect to glucose homeostasis and protection from diet-induced obesity. METHODS Here, we studied the effects of pharmacological inhibition of ACC2 using as a selective inhibitor the S enantiomer of compound 9c ([S]-9c). Selectivity was confirmed in biochemical assays using purified human ACC1 and ACC2. RESULTS (S)-9c significantly increased fatty acid oxidation in isolated extensor digitorum longus muscle from different mouse models (EC(50) 226 nmol/l). Accordingly, short-term treatment of mice with (S)-9c decreased malonyl-CoA levels in skeletal muscle and concomitantly reduced intramyocellular lipid levels. Treatment of db/db mice for 70 days with (S)-9c (10 and 30 mg/kg, by oral gavage) resulted in improved oral glucose tolerance (AUC -36%, p < 0.05), enhanced skeletal muscle 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) uptake, as well as lowered prandial glucose (-31%, p < 0.01) and HbA(1c) (-0.7%, p < 0.05). Body weight, liver triacylglycerol, plasma insulin and pancreatic insulin content were unaffected by the treatment. CONCLUSIONS/INTERPRETATION In conclusion, the ACC2-selective inhibitor (S)-9c revealed glucose-lowering effects in a mouse model of diabetes mellitus.
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Affiliation(s)
- S Glund
- CardioMetabolic Diseases Research, Boehringer Ingelheim Pharma GmbH& Co. KG, 88397, Biberach an der Riss, Germany
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89
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Kolwicz SC, Olson DP, Marney LC, Garcia-Menendez L, Synovec RE, Tian R. Cardiac-specific deletion of acetyl CoA carboxylase 2 prevents metabolic remodeling during pressure-overload hypertrophy. Circ Res 2012; 111:728-38. [PMID: 22730442 DOI: 10.1161/circresaha.112.268128] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE Decreased fatty acid oxidation (FAO) with increased reliance on glucose are hallmarks of metabolic remodeling that occurs in pathological cardiac hypertrophy and is associated with decreased myocardial energetics and impaired cardiac function. To date, it has not been tested whether prevention of the metabolic switch that occurs during the development of cardiac hypertrophy has unequivocal benefits on cardiac function and energetics. OBJECTIVE Because malonyl CoA production via acetyl CoA carboxylase 2 (ACC2) inhibits the entry of long chain fatty acids into the mitochondria, we hypothesized that mice with a cardiac-specific deletion of ACC2 (ACC2H-/-) would maintain cardiac FAO and improve function and energetics during the development of pressure-overload hypertrophy. METHODS AND RESULTS ACC2 deletion led to a significant reduction in cardiac malonyl CoA levels. In isolated perfused heart experiments, left ventricular function and oxygen consumption were similar in ACC2H-/- mice despite an ≈60% increase in FAO compared with controls (CON). After 8 weeks of pressure overload via transverse aortic constriction (TAC), ACC2H-/- mice exhibited a substrate utilization profile similar to sham animals, whereas CON-TAC hearts had decreased FAO with increased glycolysis and anaplerosis. Myocardial energetics, assessed by 31P nuclear magnetic resonance spectroscopy, and cardiac function were maintained in ACC2H-/- after 8 weeks of TAC. Furthermore, ACC2H-/--TAC demonstrated an attenuation of cardiac hypertrophy with a significant reduction in fibrosis relative to CON-TAC. CONCLUSIONS These data suggest that reversion to the fetal metabolic profile in chronic pathological hypertrophy is associated with impaired myocardial function and energetics and maintenance of the inherent cardiac metabolic profile and mitochondrial oxidative capacity is a viable therapeutic strategy.
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Affiliation(s)
- Stephen C Kolwicz
- Mitochondria and Metabolism Center, Department of Anesthesiology and Pain Medicine, University of Washington School of Medicine, 850 Republican St, Seattle, WA 98109, USA
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90
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Stephenson EJ, Camera DM, Jenkins TA, Kosari S, Lee JS, Hawley JA, Stepto NK. Skeletal muscle respiratory capacity is enhanced in rats consuming an obesogenic Western diet. Am J Physiol Endocrinol Metab 2012; 302:E1541-9. [PMID: 22496344 DOI: 10.1152/ajpendo.00590.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Obesity-induced lipid oversupply promotes skeletal muscle mitochondrial biogenesis. Previous investigations have utilized extreme high-fat diets (HFD) to induce such mitochondrial perturbations despite their disparity from human obesogenic diets. Here, we evaluate the effects of Western diet (WD)-induced obesity on skeletal muscle mitochondrial function. Long-Evans rats were given ad libitum access to either a WD [40% energy (E) from fat, 17% protein, and 43% carbohydrate (30% sucrose); n = 12] or a control diet (CON; 16% of E from fat, 21% protein, and 63% carbohydrate; n = 12) for 12 wk. Rats fed the WD consumed 23% more E than CON (P = 0.0001), which was associated with greater increases in body mass (23%, P = 0.0002) and adiposity (17%, P = 0.03). There were no differences in fasting blood glucose concentration or glucose tolerance between diets, although fasting insulin was increased by 40% (P = 0.007). Fasting serum triglycerides were also elevated in WD (86%, P = 0.001). The maximal capacity of the electron transfer system was greater following WD (37%, P = 0.02), as were the maximal activities of several mitochondrial enzymes (citrate synthase, β-hydroxyacyl-CoA dehydrogenase, carnitine palmitoyltransferase). Protein expression of citrate synthase, UCP3, and individual respiratory complexes was greater after WD (P < 0.05) despite no differences in the expression of peroxisome proliferator-activated receptor (PPAR)α, PPARδ, or PPARγ coactivator-1 mRNA or protein abundance. We conclude that the respiratory capacity of skeletal muscle is enhanced in response to the excess energy supplied by a WD. This is likely due to an increase in mitochondrial density, which at least in the short term, and in the absence of increased energy demand, may protect the tissue from lipid-induced impairments in glycemic control.
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Affiliation(s)
- Erin J Stephenson
- School of Medical Sciences, Royal Melbourne Institute of Technology University, Bundoora, Australia
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91
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Boudina S, Sena S, Sloan C, Tebbi A, Han YH, O'Neill BT, Cooksey RC, Jones D, Holland WL, McClain DA, Abel ED. Early mitochondrial adaptations in skeletal muscle to diet-induced obesity are strain dependent and determine oxidative stress and energy expenditure but not insulin sensitivity. Endocrinology 2012; 153:2677-88. [PMID: 22510273 PMCID: PMC3359615 DOI: 10.1210/en.2011-2147] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This study sought to elucidate the relationship between skeletal muscle mitochondrial dysfunction, oxidative stress, and insulin resistance in two mouse models with differential susceptibility to diet-induced obesity. We examined the time course of mitochondrial dysfunction and insulin resistance in obesity-prone C57B and obesity-resistant FVB mouse strains in response to high-fat feeding. After 5 wk, impaired insulin-mediated glucose uptake in skeletal muscle developed in both strains in the absence of any impairment in proximal insulin signaling. Impaired mitochondrial oxidative capacity preceded the development of insulin resistant glucose uptake in C57B mice in concert with increased oxidative stress in skeletal muscle. By contrast, mitochondrial uncoupling in FVB mice, which prevented oxidative stress and increased energy expenditure, did not prevent insulin resistant glucose uptake in skeletal muscle. Preventing oxidative stress in C57B mice treated systemically with an antioxidant normalized skeletal muscle mitochondrial function but failed to normalize glucose tolerance and insulin sensitivity. Furthermore, high fat-fed uncoupling protein 3 knockout mice developed increased oxidative stress that did not worsen glucose tolerance. In the evolution of diet-induced obesity and insulin resistance, initial but divergent strain-dependent mitochondrial adaptations modulate oxidative stress and energy expenditure without influencing the onset of impaired insulin-mediated glucose uptake.
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Affiliation(s)
- Sihem Boudina
- Division of Endocrinology, Metabolism, and Diabetes, Salt Lake City, Utah 84112, USA.
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92
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Murça TM, Moraes PL, Capuruço CAB, Santos SHS, Melo MB, Santos RAS, Shenoy V, Katovich MJ, Raizada MK, Ferreira AJ. Oral administration of an angiotensin-converting enzyme 2 activator ameliorates diabetes-induced cardiac dysfunction. ACTA ACUST UNITED AC 2012; 177:107-15. [PMID: 22595130 DOI: 10.1016/j.regpep.2012.05.093] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 04/09/2012] [Accepted: 05/05/2012] [Indexed: 12/29/2022]
Abstract
We evaluated the hypothesis that activation of endogenous angiotensin-converting enzyme (ACE) 2 would improve cardiac dysfunction induced by diabetes. Ten days after diabetes induction (streptozotocin, 50 mg/kg, i.v.), male Wistar rats were treated with the ACE2 activator 1-[[2-(dimethylamino)ethyl]amino]-4-(hydroxymethyl)-7-[[(4-methylphenyl)sulfonyl]oxy]-9H-xanthen-9-one (XNT, 1 mg/kg/day, gavage) or saline (control) for 30 days. Echocardiography was performed to analyze the cardiac function and kinetic fluorogenic assays were used to determine cardiac ACE and ACE2 activities. Cardiac ACE2, ACE, Mas receptor, AT(1) receptor, AT(2) receptor and collagen types I and III mRNA and ACE2, ACE, Mas, AT(1) receptor, AT(2) receptor, ERK1/2, Akt, AMPK-α and AMPK-β(1) protein were measured by qRT-PCR and western blotting techniques, respectively. Histological sections of hearts were analyzed to evaluate the presence of hypertrophy and fibrosis. Diabetic animals presented hyperglycemia and diastolic dysfunction along with cardiac hypertrophy and fibrosis. XNT treatment prevented further increase in glycemia and improved the cardiac function, as well as the hypertrophy and fibrosis. These effects were associated with increases in cardiac ACE2/ACE ratios (activity: ~26%; mRNA: ~113%; and protein: ~188%) and with a decrease in AT(1) receptor expression. Additionally, XNT inhibited ERK1/2 phosphorylation and prevented changes in AMPK-α and AMPK-β(1) expressions. XNT treatment did not induce any significant change in AT(2) receptor and Akt expression. These results indicate that activation of intrinsic cardiac ACE2 by oral XNT treatment protects the heart against diabetes-induced dysfunction through mechanisms involving ACE, ACE2, ERK1/2, AMPK-α and AMPK-β(1) modulations.
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Affiliation(s)
- Tatiane M Murça
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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93
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Chocron ES, Sayre NL, Holstein D, Saelim N, Ibdah JA, Dong LQ, Zhu X, Cheng SY, Lechleiter JD. The trifunctional protein mediates thyroid hormone receptor-dependent stimulation of mitochondria metabolism. Mol Endocrinol 2012; 26:1117-28. [PMID: 22570332 DOI: 10.1210/me.2011-1348] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We previously demonstrated that the thyroid hormone, T(3), acutely stimulates mitochondrial metabolism in a thyroid hormone receptor (TR)-dependent manner. T(3) has also recently been shown to stimulate mitochondrial fatty acid oxidation (FAO). Here we report that TR-dependent stimulation of metabolism is mediated by the mitochondrial trifunctional protein (MTP), the enzyme responsible for long-chain FAO. Stimulation of FAO was significant in cells that expressed a nonnuclear amino terminus shortened TR isoform (sTR(43)) but not in adult fibroblasts cultured from mice deficient in both TRα and TRβ isoforms (TRα(-/-)β(-/-)). Mouse embryonic fibroblasts deficient in MTP (MTP(-/-)) did not support T(3)-stimulated FAO. Inhibition of fatty-acid trafficking into mitochondria using the AMP-activated protein kinase inhibitor 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyrrazolo[1,5-a]-pyrimidine (compound C) or the carnitine palmitoyltransferase 1 inhibitor etomoxir prevented T(3)-stimulated FAO. However, T(3) treatment could increase FAO when AMP-activated protein kinase was maximally activated, indicating an alternate mechanism of T(3)-stimulated FAO exists, even when trafficking is presumably high. MTPα protein levels and higher molecular weight complexes of MTP subunits were increased by T(3) treatment. We suggest that T(3)-induced increases in mitochondrial metabolism are at least in part mediated by a T(3)-shortened TR isoform-dependent stabilization of the MTP complex, which appears to lower MTP subunit turnover.
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Affiliation(s)
- E Sandra Chocron
- Departments Of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA
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94
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Muoio DM, Neufer PD. Lipid-induced mitochondrial stress and insulin action in muscle. Cell Metab 2012; 15:595-605. [PMID: 22560212 PMCID: PMC3348508 DOI: 10.1016/j.cmet.2012.04.010] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 01/16/2012] [Accepted: 04/13/2012] [Indexed: 12/14/2022]
Abstract
The interplay between mitochondrial energetics, lipid balance, and muscle insulin sensitivity has remained a topic of intense interest and debate for decades. One popular view suggests that increased oxidative capacity benefits metabolic wellness, based on the premise that it is healthier to burn fat than glucose. Attempts to test this hypothesis using genetically modified mouse models have produced contradictory results and instead link muscle insulin resistance to excessive fat oxidation, acylcarnitine production, and increased mitochondrial H(2)O(2)-emitting potential. Here, we consider emerging evidence that insulin action in muscle is driven principally by mitochondrial load and redox signaling rather than oxidative capacity.
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Affiliation(s)
- Deborah M Muoio
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, NC 27710, USA.
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95
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Abu-Elheiga L, Wu H, Gu Z, Wakil SJ. Reply to Hoehn et al.: Phenotypic Discrepancies in Acetyl-CoA Carboxylase 2-deficient Mice. J Biol Chem 2012. [DOI: 10.1074/jbc.o112.362939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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96
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Abu-Elheiga L, Wu H, Gu Z, Bressler R, Wakil SJ. Acetyl-CoA carboxylase 2-/- mutant mice are protected against fatty liver under high-fat, high-carbohydrate dietary and de novo lipogenic conditions. J Biol Chem 2012; 287:12578-88. [PMID: 22362781 DOI: 10.1074/jbc.m111.309559] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Hepatic fat accumulation resulting from increased de novo fatty acid synthesis leads to hepatic steatosis and hepatic insulin resistance. We have shown previously that acetyl-CoA carboxylase 2 (Acc2(-/-)) mutant mice, when fed a high-fat (HF) or high-fat, high-carbohydrate (HFHC) diet, are protected against diet-induced obesity and maintained whole body and hepatic insulin sensitivity. To determine the effect of an ACC2 deletion on hepatic fat metabolism, we studied the regulation of the enzymes involved in the lipogenic pathway under Western HFHC dietary and de novo lipogenic conditions. After completing the HFHC regimen, Acc2(-/-) mutant mice were found to have lower body weight, smaller epididymal fat pads, lower blood levels of nonesterified fatty acids and triglycerides, and higher hepatic cholesterol than wild-type mice. Significant up-regulation of lipogenic enzymes and an elevation in hepatic peroxisome proliferator-activated receptor-γ (PPAR-γ) protein were found in Acc2(-/-) mutant mice under de novo lipogenic conditions. The increase in lipogenic enzyme levels was accompanied by up-regulation of the transcription factors, sterol regulatory element-binding proteins 1 and 2, and carbohydrate response element-binding protein. In contrast, hepatic levels of the PPAR-γ and PPAR-α proteins were significantly lower in the Acc2(-/-) mutant mice fed an HFHC diet. When compared with wild-type mice fed the same diet, Acc2(-/-) mutant mice exhibited a similar level of AKT but with a significant increase in pAKT. Hence, deleting ACC2 ameliorates the metabolic syndrome and protects against fatty liver despite increased de novo lipogenesis and dietary conditions known to induce obesity and diabetes.
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Affiliation(s)
- Lutfi Abu-Elheiga
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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97
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Klaus S, Keipert S, Rossmeisl M, Kopecky J. Augmenting energy expenditure by mitochondrial uncoupling: a role of AMP-activated protein kinase. GENES AND NUTRITION 2011; 7:369-86. [PMID: 22139637 DOI: 10.1007/s12263-011-0260-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 11/18/2011] [Indexed: 11/28/2022]
Abstract
Strategies to prevent and treat obesity aim to decrease energy intake and/or increase energy expenditure. Regarding the increase of energy expenditure, two key intracellular targets may be considered (1) mitochondrial oxidative phosphorylation, the major site of ATP production, and (2) AMP-activated protein kinase (AMPK), the master regulator of cellular energy homeostasis. Experiments performed mainly in transgenic mice revealed a possibility to ameliorate obesity and associated disorders by mitochondrial uncoupling in metabolically relevant tissues, especially in white adipose tissue (WAT), skeletal muscle (SM), and liver. Thus, ectopic expression of brown fat-specific mitochondrial uncoupling protein 1 (UCP1) elicited major metabolic effects both at the cellular/tissue level and at the whole-body level. In addition to expected increases in energy expenditure, surprisingly complex phenotypic effects were detected. The consequences of mitochondrial uncoupling in WAT and SM are not identical, showing robust and stable obesity resistance accompanied by improvement of lipid metabolism in the case of ectopic UCP1 in WAT, while preservation of insulin sensitivity in the context of high-fat feeding represents the major outcome of muscle UCP1 expression. These complex responses could be largely explained by tissue-specific activation of AMPK, triggered by a depression of cellular energy charge. Experimental data support the idea that (1) while being always activated in response to mitochondrial uncoupling and compromised intracellular energy status in general, AMPK could augment energy expenditure and mediate local as well as whole-body effects; and (2) activation of AMPK alone does not lead to induction of energy expenditure and weight reduction.
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Affiliation(s)
- Susanne Klaus
- German Institute of Human Nutrition, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany
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98
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Gahete MD, Córdoba-Chacón J, Anadumaka CV, Lin Q, Brüning JC, Kahn CR, Luque RM, Kineman RD. Elevated GH/IGF-I, due to somatotrope-specific loss of both IGF-I and insulin receptors, alters glucose homeostasis and insulin sensitivity in a diet-dependent manner. Endocrinology 2011; 152:4825-37. [PMID: 21990313 PMCID: PMC3230054 DOI: 10.1210/en.2011-1447] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A unique mouse model was developed with elevated endogenous GH (2- to 3-fold) and IGF-I (1.2- to 1.4-fold), due to somatotrope-specific Cre-mediated inactivation of IGF-I receptor (IgfIr) and insulin receptor (Insr) genes (IgfIr,Insr(rGHpCre), referred to as HiGH mice). We demonstrate that the metabolic phenotype of HiGH mice is diet dependent and differs from that observed in other mouse models of GH excess due to ectopic heterologous transgene expression or pituitary tumor formation. Elevated endogenous GH promotes lean mass and whole-body lipid oxidation but has minimal effects on adiposity, even in response to diet-induced obesity. When caloric intake is moderated, elevated GH improves glucose clearance, despite low/normal insulin sensitivity, which may be explained in part by enhanced IGF-I and insulin output. However, when caloric intake is in excess, elevated GH promotes hepatic lipid accumulation, insulin resistance, hyperglycemia, and ketosis. The HiGH mouse model represents a useful tool to study the role endogenous circulating GH levels play in regulating health and disease.
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Affiliation(s)
- Manuel D Gahete
- Jesse Brown Veterans Affairs Medical Center, Research and Development Division, 820 South Damen Avenue, Chicago, Illinois 60612, USA
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99
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Dulloo AG. The search for compounds that stimulate thermogenesis in obesity management: from pharmaceuticals to functional food ingredients. Obes Rev 2011; 12:866-83. [PMID: 21951333 DOI: 10.1111/j.1467-789x.2011.00909.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The concept of managing obesity through the stimulation of thermogenesis is currently a focus of considerable attention by the pharmaceutical, nutraceutical and functional food industries. This paper first reviews the landmark discoveries that have fuelled the search for thermogenic anti-obesity products that range from single-target drugs to multi-target functional foods. It subsequently analyses the thermogenic and fat-oxidizing potentials of a wide array of bioactive food ingredients which are categorized under methylxanthines, polyphenols, capsaicinoids/capsinoids, minerals, proteins/amino acids, carbohydrates/sugars and fats/fatty acids. The main outcome of this analysis is that the compounds or combination of compounds with thermogenic and fat-oxidizing potentials are those that possess both sympathomimetic stimulatory activity and acetyl-coA carboxylase inhibitory property, and are capable of targeting both skeletal muscle and brown adipose tissue. The thermogenic potentials of products so far tested in humans range from marginal to modest, i.e. 2-5% above daily energy expenditure. With an increasing number of bioactive food ingredients awaiting screening in humans, there is hope that this thermogenic potential could be safely increased to 10-15% above daily energy expenditure - which would have clinically significant impact on weight management, particularly in the prevention of obesity and in improving the long-term prognosis of post-slimming weight maintenance.
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Affiliation(s)
- A G Dulloo
- Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland.
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100
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Ma L, Mondal AK, Murea M, Sharma NK, Tönjes A, Langberg KA, Das SK, Franks PW, Kovacs P, Antinozzi PA, Stumvoll M, Parks JS, Elbein SC, Freedman BI. The effect of ACACB cis-variants on gene expression and metabolic traits. PLoS One 2011; 6:e23860. [PMID: 21887335 PMCID: PMC3162605 DOI: 10.1371/journal.pone.0023860] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 07/26/2011] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Acetyl Coenzyme A carboxylase β (ACACB) is the rate-limiting enzyme in fatty acid oxidation, and continuous fatty acid oxidation in Acacb knock-out mice increases insulin sensitivity. Systematic human studies have not been performed to evaluate whether ACACB variants regulate gene expression and insulin sensitivity in skeletal muscle and adipose tissues. We sought to determine whether ACACB transcribed variants were associated with ACACB gene expression and insulin sensitivity in non-diabetic African American (AA) and European American (EA) adults. METHODS ACACB transcribed single nucleotide polymorphisms (SNPs) were genotyped in 105 EAs and 46 AAs whose body mass index (BMI), lipid profiles and ACACB gene expression in subcutaneous adipose and skeletal muscle had been measured. Allelic expression imbalance (AEI) was assessed in lymphoblast cell lines from heterozygous subjects in an additional EA sample (n = 95). Selected SNPs were further examined for association with insulin sensitivity in a cohort of 417 EAs and 153 AAs. RESULTS ACACB transcribed SNP rs2075260 (A/G) was associated with adipose ACACB messenger RNA expression in EAs and AAs (p = 3.8×10(-5), dominant model in meta-analysis, Stouffer method), with the (A) allele representing lower gene expression in adipose and higher insulin sensitivity in EAs (p = 0.04). In EAs, adipose ACACB expression was negatively associated with age and sex-adjusted BMI (r = -0.35, p = 0.0002). CONCLUSIONS Common variants within the ACACB locus appear to regulate adipose gene expression in humans. Body fat (represented by BMI) may further regulate adipose ACACB gene expression in the EA population.
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Affiliation(s)
- Lijun Ma
- Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America.
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