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Andrich DE, Ou Y, Melbouci L, Leduc-Gaudet JP, Auclair N, Mercier J, Secco B, Tomaz LM, Gouspillou G, Danialou G, Comtois AS, St-Pierre DH. Altered Lipid Metabolism Impairs Skeletal Muscle Force in Young Rats Submitted to a Short-Term High-Fat Diet. Front Physiol 2018; 9:1327. [PMID: 30356919 PMCID: PMC6190893 DOI: 10.3389/fphys.2018.01327] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 09/03/2018] [Indexed: 12/15/2022] Open
Abstract
Obesity and ensuing disorders are increasingly prevalent in young populations. Prolonged exposure to high-fat diets (HFD) and excessive lipid accumulation were recently suggested to impair skeletal muscle functions in rodents. We aimed to determine the effects of a short-term HFD on skeletal muscle function in young rats. Young male Wistar rats (100–125 g) were fed HFD or a regular chow diet (RCD) for 14 days. Specific force, resistance to fatigue and recovery were tested in extensor digitorum longus (EDL; glycolytic) and soleus (SOL; oxidative) muscles using an ex vivo muscle contractility system. Muscle fiber typing and insulin signaling were analyzed while intramyocellular lipid droplets (LD) were characterized. Expression of key markers of lipid metabolism was also measured. Weight gain was similar for both groups. Specific force was decreased in SOL, but not in EDL of HFD rats. Muscle resistance to fatigue and force recovery were not altered in response to the diets. Similarly, muscle fiber type distribution and insulin signaling were not influenced by HFD. On the other hand, percent area and average size of intramyocellular LDs were significantly increased in the SOL of HFD rats. These effects were consistent with the increased expression of several mediators of lipid metabolism in the SOL muscle. A short-term HFD impairs specific force and alters lipid metabolism in SOL, but not EDL muscles of young rats. This indicates the importance of clarifying the early mechanisms through which lipid metabolism affects skeletal muscle functions in response to obesogenic diets in young populations.
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Affiliation(s)
- David E Andrich
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Département des Sciences Biologiques, Université du Québec à Montréal, Montreal, QC, Canada
| | - Ya Ou
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Centre de Recherche du CHU Sainte-Justine, Montreal, QC, Canada
| | - Lilya Melbouci
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Centre de Recherche du CHU Sainte-Justine, Montreal, QC, Canada
| | - Jean-Philippe Leduc-Gaudet
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
| | - Nickolas Auclair
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Centre de Recherche du CHU Sainte-Justine, Montreal, QC, Canada
| | - Jocelyne Mercier
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Centre de Recherche du CHU Sainte-Justine, Montreal, QC, Canada
| | - Blandine Secco
- Centre de Recherche de l'Institut de Cardiologie et de Pneumologie de Québec, Ville de Québec, QC, Canada
| | - Luciane Magri Tomaz
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Centre de Recherche du CHU Sainte-Justine, Montreal, QC, Canada
| | - Gilles Gouspillou
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
| | - Gawiyou Danialou
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Royal Military College Saint-Jean, Saint-Jean-sur-Richelieu, QC, Canada
| | - Alain-Steve Comtois
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
| | - David H St-Pierre
- Département des Sciences de l'Activités Physique, Université du Québec à Montréal, Montreal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada.,Centre de Recherche du CHU Sainte-Justine, Montreal, QC, Canada
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Wu W, Xu Z, Zhang L, Liu J, Feng J, Wang X, Shan T, Wang Y. Muscle-specific deletion of Prkaa1 enhances skeletal muscle lipid accumulation in mice fed a high-fat diet. J Physiol Biochem 2017; 74:195-205. [DOI: 10.1007/s13105-017-0604-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 12/20/2017] [Indexed: 12/31/2022]
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3
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Pozo M, Rodríguez-Rodríguez R, Ramírez S, Seoane-Collazo P, López M, Serra D, Herrero L, Casals N. Hypothalamic Regulation of Liver and Muscle Nutrient Partitioning by Brain-Specific Carnitine Palmitoyltransferase 1C in Male Mice. Endocrinology 2017; 158:2226-2238. [PMID: 28472467 DOI: 10.1210/en.2017-00151] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/28/2017] [Indexed: 11/19/2022]
Abstract
Carnitine palmitoyltransferase (CPT) 1C, a brain-specific protein localized in the endoplasmic reticulum of neurons, is expressed in almost all brain regions. Based on global knockout (KO) models, CPT1C has demonstrated relevance in hippocampus-dependent spatial learning and in hypothalamic regulation of energy balance. Specifically, it has been shown that CPT1C is protective against high-fat diet-induced obesity (DIO), and that CPT1C KO mice show reduced peripheral fatty acid oxidation (FAO) during both fasting and DIO. However, the mechanisms mediating CPT1C-dependent regulation of energy homeostasis remain unclear. Here, we focus on the mechanistic understanding of hypothalamic CPT1C on the regulation of fuel selection in liver and muscle of male mice during energy deprivation situations, such as fasting. In CPT1C-deficient mice, modulation of the main hypothalamic energy sensors (5' adenosine monophosphate-activated protein kinase, Sirtuin 1, and mammalian target of rapamycin) was impaired and plasma catecholamine levels were decreased. Consequently, CPT1C-deficient mice presented defective fasting-induced FAO in liver, leading to higher triacylglycerol accumulation and lower glycogen levels. Moreover, muscle pyruvate dehydrogenase activity was increased, which was indicative of glycolysis enhancement. The respiratory quotient did not decrease in CPT1C KO mice after 48 hours of fasting, confirming a defective switch on fuel substrate selection under hypoglycemia. Phenotype reversion studies identified the mediobasal hypothalamus (MBH) as the main area mediating CPT1C effects on fuel selection. Overall, our data demonstrate that CPT1C in the MBH is necessary for proper hypothalamic sensing of a negative energy balance and fuel partitioning in liver and muscle.
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Affiliation(s)
- Macarena Pozo
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Barcelona, Spain
| | - Rosalía Rodríguez-Rodríguez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Barcelona, Spain
| | - Sara Ramírez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Barcelona, Spain
| | - Patricia Seoane-Collazo
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain
| | - Miguel López
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Dolors Serra
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Department of Biochemistry and Physiology, Faculty of Pharmacy, Institut de Biomedicina de la Universitat de Barcelona, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Laura Herrero
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Department of Biochemistry and Physiology, Faculty of Pharmacy, Institut de Biomedicina de la Universitat de Barcelona, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Núria Casals
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28029 Madrid, Spain
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4
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Wu W, Feng J, Jiang D, Zhou X, Jiang Q, Cai M, Wang X, Shan T, Wang Y. AMPK regulates lipid accumulation in skeletal muscle cells through FTO-dependent demethylation of N 6-methyladenosine. Sci Rep 2017; 7:41606. [PMID: 28176824 PMCID: PMC5296945 DOI: 10.1038/srep41606] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 12/22/2016] [Indexed: 11/28/2022] Open
Abstract
Skeletal muscle plays important roles in whole-body energy homeostasis. Excessive skeletal muscle lipid accumulation is associated with some metabolic diseases such as obesity and Type 2 Diabetes. The energy sensor AMPK (AMP-activated protein kinase) is a key regulator of skeletal muscle lipid metabolism, but the precise regulatory mechanism remains to be elucidated. Here, we provide a novel mechanism by which AMPK regulates skeletal muscle lipid accumulation through fat mass and obesity-associated protein (FTO)-dependent demethylation of N6-methyladenosine (m6A). We confirmed an inverse correlation between AMPK and skeletal muscle lipid content. Moreover, inhibition of AMPK enhanced lipid accumulation, while activation of AMPK reduced lipid accumulation in skeletal muscle cells. Notably, we found that mRNA m6A methylation levels were inversely correlated with lipid content in skeletal muscle. Furthermore, AMPK positively regulated the m6A methylation levels of mRNA, which could negatively regulate lipid accumulation in C2C12. At the molecular level, we demonstrated that AMPK regulated lipid accumulation in skeletal muscle cells by regulating FTO expression and FTO-dependent demethylation of m6A. Together, these results provide a novel regulatory mechanism of AMPK on lipid metabolism in skeletal muscle cells and suggest the possibility of controlling skeletal muscle lipid deposition by targeting AMPK or using m6A related drugs.
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Affiliation(s)
- Weiche Wu
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Jie Feng
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Denghu Jiang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Xihong Zhou
- Institute of Subtropical Agriculture, The Chinese Academy of Science, Changsha, Hunan 410125, P. R. China
| | - Qin Jiang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Min Cai
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Xinxia Wang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Tizhong Shan
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Yizhen Wang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
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5
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Biswas D, Ghosh M, Kumar S, Chakrabarti P. PPARα-ATGL pathway improves muscle mitochondrial metabolism: implication in aging. FASEB J 2016; 30:3822-3834. [PMID: 27485820 DOI: 10.1096/fj.201600571rr] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/27/2016] [Indexed: 02/05/2023]
Abstract
Adipose triglyceride lipase (ATGL) maintains an optimum mitochondrial function putatively by generating cognate ligands for peroxisome proliferator-activated receptor α (PPARα), which, together with PPARγ coactivator-1α (PGC1α), regulate muscle mitochondrial biogenesis. However, the cross-talk between ATGL and PPARα in skeletal muscle mitochondrial metabolism and its implication in chronological aging is poorly understood. The role of ATGL in muscle mitochondrial metabolism was studied by overexpressing and depleting the gene and studying its downstream effect in cultured myotubes and in murine skeletal muscle. We found that PPARα directly induces ATGL expression during myogenesis. Overexpression of ATGL significantly enhanced while depletion of ATGL attenuated mitochondrial oxidative phosphorylation and fatty acid oxidation without alteration in mitochondrial content, and it rendered PPARα and PGC1α redundant in promoting mitochondrial oxidative function. However, ATGL did not alter PPARα-dependent lipid accumulation and insulin sensitivity. In middle-aged rats, ATGL expression was higher and correlated with PPARα expression and sustained fatty acid oxidation in oxidative soleus muscle. Fenofibrate feeding further induced ATGL expression selectively in this muscle compartment. These findings illustrate that PPARα and ATGL constitute a regulatory pathway in skeletal muscle, suggesting their role as a mitochondrial metabolic reserve.-Biswas, D., Ghosh, M., Kumar, S., Chakrabarti, P. PPARα-ATGL pathway improves muscle mitochondrial metabolism: implication in aging.
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Affiliation(s)
- Dipsikha Biswas
- Division of Cell Biology and Physiology, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, Kolkata, India; and
| | - Mainak Ghosh
- Division of Cell Biology and Physiology, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, Kolkata, India; and
| | - Subhankar Kumar
- Department of Physiology, Institute of Postgraduate Medical Education and Research, Kolkata, India
| | - Partha Chakrabarti
- Division of Cell Biology and Physiology, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, Kolkata, India; and
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6
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Meex RCR, Hoy AJ, Mason RM, Martin SD, McGee SL, Bruce CR, Watt MJ. ATGL-mediated triglyceride turnover and the regulation of mitochondrial capacity in skeletal muscle. Am J Physiol Endocrinol Metab 2015; 308:E960-70. [PMID: 25852007 DOI: 10.1152/ajpendo.00598.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 04/02/2015] [Indexed: 12/11/2022]
Abstract
Emerging evidence indicates that skeletal muscle lipid droplets are an important control point for intracellular lipid homeostasis and that regulating fatty acid fluxes from lipid droplets might influence mitochondrial capacity. We used pharmacological blockers of the major triglyceride lipases, adipose triglyceride lipase (ATGL) and hormone-sensitive lipase, to show that a large proportion of the fatty acids that are transported into myotubes are trafficked through the intramyocellular triglyceride pool. We next tested whether increasing lipolysis from intramyocellular lipid droplets could activate transcriptional responses to enhance mitochondrial and fatty acid oxidative capacity. ATGL was overexpressed by adenoviral and adenoassociated viral infection in C2C12 myotubes and the tibialis anterior muscle of C57Bl/6 mice, respectively. ATGL overexpression in C2C12 myotubes increased lipolysis, which was associated with increased peroxisome proliferator-activated receptor (PPAR)-∂ activity, transcriptional upregulation of some PPAR∂ target genes, and enhanced mitochondrial capacity. The transcriptional responses were specific to ATGL actions and not a generalized increase in fatty acid flux in the myotubes. Marked ATGL overexpression (20-fold) induced modest molecular changes in the skeletal muscle of mice, but these effects were not sufficient to alter fatty acid oxidation. Together, these data demonstrate the importance of lipid droplets for myocellular fatty acid trafficking and the capacity to modulate mitochondrial capacity by enhancing lipid droplet lipolysis in vitro; however, this adaptive program is of minor importance when superimposing the normal metabolic stresses encountered in free-moving animals.
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Affiliation(s)
- Ruth C R Meex
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Andrew J Hoy
- Discipline of Physiology, School of Medical Sciences & Bosch Institute, University of Sydney, New South Wales, Australia; Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, University of Sydney, Sydney, New South Wales, Australia
| | - Rachael M Mason
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Sheree D Martin
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Burwood, Victoria, Australia; and
| | - Sean L McGee
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Burwood, Victoria, Australia; and
| | - Clinton R Bruce
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
| | - Matthew J Watt
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia;
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7
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Dubé JJ, Sitnick MT, Schoiswohl G, Wills RC, Basantani MK, Cai L, Pulinilkunnil T, Kershaw EE. Adipose triglyceride lipase deletion from adipocytes, but not skeletal myocytes, impairs acute exercise performance in mice. Am J Physiol Endocrinol Metab 2015; 308:E879-90. [PMID: 25783895 PMCID: PMC4436997 DOI: 10.1152/ajpendo.00530.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 03/09/2015] [Indexed: 12/22/2022]
Abstract
Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme mediating triacylglycerol hydrolysis in virtually all cells, including adipocytes and skeletal myocytes, and hence, plays a critical role in mobilizing fatty acids. Global ATGL deficiency promotes skeletal myopathy and exercise intolerance in mice and humans, and yet the tissue-specific contributions to these phenotypes remain unknown. The goal of this study was to determine the relative contribution of ATGL-mediated triacylglycerol hydrolysis in adipocytes vs. skeletal myocytes to acute exercise performance. To achieve this goal, we generated murine models with adipocyte- and skeletal myocyte-specific targeted deletion of ATGL. We then subjected untrained mice to acute peak and submaximal exercise interventions and assessed exercise performance and energy substrate metabolism. Impaired ATGL-mediated lipolysis within adipocytes reduced peak and submaximal exercise performance, reduced peripheral energy substrate availability, shifted energy substrate preference toward carbohydrate oxidation, and decreased HSL Ser(660) phosphorylation and mitochondrial respiration within skeletal muscle. In contrast, impaired ATGL-mediated lipolysis within skeletal myocytes was not sufficient to reduce peak and submaximal exercise performance or peripheral energy substrate availability and instead tended to enhance metabolic flexibility during peak exercise. Furthermore, the expanded intramyocellular triacylglycerol pool in these mice was reduced following exercise in association with preserved HSL phosphorylation, suggesting that HSL may compensate for impaired ATGL action in skeletal muscle during exercise. These data suggest that adipocyte rather than skeletal myocyte ATGL-mediated lipolysis plays a greater role during acute exercise in part because of compensatory mechanisms that maintain lipolysis in muscle, but not adipose tissue, when ATGL is absent.
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Affiliation(s)
- John J Dubé
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Mitch T Sitnick
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Gabriele Schoiswohl
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Rachel C Wills
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Mahesh K Basantani
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Lingzhi Cai
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Thomas Pulinilkunnil
- Department of Biochemistry and Molecular Biology, Dalhousie Medicine New Brunswick, Dalhousie University, Saint John, New Brunswick, Canada
| | - Erin E Kershaw
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
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8
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Shan T, Zhang P, Bi P, Kuang S. Lkb1 deletion promotes ectopic lipid accumulation in muscle progenitor cells and mature muscles. J Cell Physiol 2015; 230:1033-41. [PMID: 25251157 DOI: 10.1002/jcp.24831] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 09/19/2014] [Indexed: 12/25/2022]
Abstract
Excessive intramyocellular triglycerides (muscle lipids) are associated with reduced contractile function, insulin resistance, and Type 2 diabetes, but what governs lipid accumulation in muscle is unclear. Here we report a role of Lkb1 in regulating lipid metabolism in muscle stem cells and their descendent mature muscles. We used Myod(Cre) and Lkb1(flox/flox) mice to specifically delete Lkb1 in myogenic cells including stem and differentiated cells, and examined the lipid accumulation and gene expression of myoblasts cultured from muscle stem cells (satellite cells). Genetic deletion of Lkb1 in myogenic progenitors led to elevated expression of lipogenic genes and ectopic lipid accumulation in proliferating myoblasts. Interestingly, the Lkb1-deficient myoblasts differentiated into adipocyte-like cells upon adipogenic induction. However, these adipocyte-like cells maintained myogenic gene expression with reduced ability to form myotubes efficiently. Activation of AMPK by AICAR prevented ectopic lipid formation in the Lkb1-null myoblasts. Notably, Lkb1-deficient muscles accumulated excessive lipids in vivo in response to high-fat diet feeding. These results demonstrate that Lkb1 acts through AMPK to limit lipid deposition in muscle stem cells and their derivative mature muscles, and point to the possibility of controlling muscle lipid content using AMPK activating drugs.
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Affiliation(s)
- Tizhong Shan
- Department of Animal Science, Purdue University, West Lafayette, Indiana
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9
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Coelho M, Nunes P, Mendes VM, Manadas B, Heerschap A, Jones JG. Effect of Global ATGL Knockout on Murine Fasting Glucose Kinetics. J Diabetes Res 2015; 2015:542029. [PMID: 26236747 PMCID: PMC4506825 DOI: 10.1155/2015/542029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/08/2015] [Indexed: 12/25/2022] Open
Abstract
Mice deficient in adipose triglyceride lipase (ATGL(-/-)) present elevated ectopic lipid levels but are paradoxically glucose-tolerant. Measurement of endogenous glucose production (EGP) and Cori cycle activity provide insights into the maintenance of glycemic control in these animals. These parameters were determined in 7 wild-type (ATGL(+/-)) and 6 ATGL(-/-) mice by a primed-infusion of [U-(13)C6]glucose followed by LC-MS/MS targeted mass-isotopomer analysis of blood glucose. EGP was quantified by isotope dilution of [U-(13)C6]glucose while Cori cycling was estimated by analysis of glucose triose (13)C-isotopomers. Fasting plasma free fatty-acids were significantly lower in ATGL(-/-) versus control mice (0.43 ± 0.05 mM versus 0.73 ± 0.11 mM, P < 0.05). Six-hour fasting EGP rates were identical for both ATGL(-/-) and control mice (79 ± 11 versus 71 ± 7 μmol/kg/min, resp.). Peripheral glucose metabolism was dominated by Cori cycling (80 ± 2% and 82 ± 7% of glucose disposal for ATGL(-/-) and control mice, resp.) indicating that peripheral glucose oxidation was not significantly upregulated in ATGL(-/-) mice under these conditions. The glucose (13)C-isotopomer distributions in both ATGL(-/-) and control mice were consistent with extensive hepatic pyruvate recycling. This suggests that gluconeogenic outflow from the Krebs cycle was also well compensated in ATGL(-/-) mice.
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Affiliation(s)
- Margarida Coelho
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | | | - Vera M. Mendes
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Bruno Manadas
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Arend Heerschap
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands
| | - John G. Jones
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Portuguese Diabetes Association (APDP), Lisbon, Portugal
- *John G. Jones:
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10
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Nunes PM, Wright AJ, Veltien A, van Asten JJA, Tack CJ, Jones JG, Heerschap A. Dietary lipids do not contribute to the higher hepatic triglyceride levels of fructose- compared to glucose-fed mice. FASEB J 2014; 28:1988-97. [PMID: 24500922 DOI: 10.1096/fj.13-241208] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fructose consumption has been associated with the surge in obesity and dyslipidemia. This may be mediated by the fructose effects on hepatic lipids and ATP levels. Fructose metabolism provides carbons for de novo lipogenesis (DNL) and stimulates enterocyte secretion of apoB48. Thus, fructose-induced hepatic triglyceride (HTG) accumulation can be attributed to both DNL stimulation and dietary lipid absorption. The aim of this study was to assess the effects of fructose diet on HTG and ATP content and the contributions of dietary lipids and DNL to HTG. Measurements were performed in vivo in mice by magnetic resonance imaging (MRI) and novel magnetic resonance spectroscopy (MRS) approaches. Abdominal adipose tissue volume and intramyocellular lipid levels were comparable between 8-wk fructose- and glucose-fed mice. HTG levels were ∼1.5-fold higher in fructose-fed than in glucose-fed mice (P<0.05). Metabolic flux analysis by (13)C and (2)H MRS showed that this was not due to dietary lipid absorption, but due to DNL stimulation. The contribution of oral lipids to HTG was, after 5 h, 1.60 ± 0.23% for fructose and 2.16 ± 0.35% for glucose diets (P=0.26), whereas that of DNL was higher in fructose than in glucose diets (2.55±0.51 vs.1.13±0.24%, P=0.01). Hepatic energy status, assessed by (31)P MRS, was similar for fructose- and glucose-fed mice. Fructose-induced HTG accumulation is better explained by DNL and not by dietary lipid uptake, while not compromising ATP homeostasis.
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Affiliation(s)
- Patricia M Nunes
- 1Department of Physiology and Metabolism, National Institute for Medical Research, the Ridgeway, Mill Hill, NW7 1AA, London, UK.
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Kratky D, Obrowsky S, Kolb D, Radovic B. Pleiotropic regulation of mitochondrial function by adipose triglyceride lipase-mediated lipolysis. Biochimie 2014; 96:106-12. [PMID: 23827855 PMCID: PMC3859496 DOI: 10.1016/j.biochi.2013.06.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/20/2013] [Indexed: 12/12/2022]
Abstract
Lipolysis is defined as the catabolism of triacylglycerols (TGs) stored in cellular lipid droplets. Recent discoveries of essential lipolytic enzymes and characterization of numerous regulatory proteins and mechanisms have fundamentally changed our perception of lipolysis and its impact on cellular metabolism. Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme for TG catabolism in most cells and tissues. This review focuses on recent advances in understanding the (patho)physiological impact due to defective lipolysis by ATGL deficiency on mitochondrial (dys)function. Depending on the type of cells and tissues investigated, absence of ATGL has pleiotropic roles in mitochondrial function.
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Affiliation(s)
- Dagmar Kratky
- Institute of Molecular Biology and Biochemistry, Center for Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria.
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12
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Differential Expressions of G0/G1 Switch Gene 2 and Comparative Gene Identification-58 are Associated with Fat Content in Bovine Muscle. Lipids 2013; 49:1-14. [DOI: 10.1007/s11745-013-3866-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/05/2013] [Indexed: 12/17/2022]
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13
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Sitnick MT, Basantani MK, Cai L, Schoiswohl G, Yazbeck CF, Distefano G, Ritov V, DeLany JP, Schreiber R, Stolz DB, Gardner NP, Kienesberger PC, Pulinilkunnil T, Zechner R, Goodpaster BH, Coen P, Kershaw EE. Skeletal muscle triacylglycerol hydrolysis does not influence metabolic complications of obesity. Diabetes 2013; 62:3350-61. [PMID: 23835334 PMCID: PMC3781480 DOI: 10.2337/db13-0500] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Intramyocellular triacylglycerol (IMTG) accumulation is highly associated with insulin resistance and metabolic complications of obesity (lipotoxicity), whereas comparable IMTG accumulation in endurance-trained athletes is associated with insulin sensitivity (the athlete's paradox). Despite these findings, it remains unclear whether changes in IMTG accumulation and metabolism per se influence muscle-specific and systemic metabolic homeostasis and insulin responsiveness. By mediating the rate-limiting step in triacylglycerol hydrolysis, adipose triglyceride lipase (ATGL) has been proposed to influence the storage/production of deleterious as well as essential lipid metabolites. However, the physiological relevance of ATGL-mediated triacylglycerol hydrolysis in skeletal muscle remains unknown. To determine the contribution of IMTG hydrolysis to tissue-specific and systemic metabolic phenotypes in the context of obesity, we generated mice with targeted deletion or transgenic overexpression of ATGL exclusively in skeletal muscle. Despite dramatic changes in IMTG content on both chow and high-fat diets, modulation of ATGL-mediated IMTG hydrolysis did not significantly influence systemic energy, lipid, or glucose homeostasis, nor did it influence insulin responsiveness or mitochondrial function. These data argue against a role for altered IMTG accumulation and lipolysis in muscle insulin resistance and metabolic complications of obesity.
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Affiliation(s)
- Mitch T. Sitnick
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Mahesh K. Basantani
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Lingzhi Cai
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Gabriele Schoiswohl
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Cynthia F. Yazbeck
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Giovanna Distefano
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Vladimir Ritov
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - James P. DeLany
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Donna B. Stolz
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Noah P. Gardner
- Novartis Institute of Biomedical Research, Cambridge, Massachusetts
| | - Petra C. Kienesberger
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, New Brunswick, Canada
| | - Thomas Pulinilkunnil
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, New Brunswick, Canada
| | - Rudolf Zechner
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Bret H. Goodpaster
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Paul Coen
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Health and Physical Activity, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Erin E. Kershaw
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Corresponding author: Erin E. Kershaw,
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14
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Gineste C, Le Fur Y, Vilmen C, Le Troter A, Pecchi E, Cozzone PJ, Hardeman EC, Bendahan D, Gondin J. Combined MRI and ³¹P-MRS investigations of the ACTA1(H40Y) mouse model of nemaline myopathy show impaired muscle function and altered energy metabolism. PLoS One 2013; 8:e61517. [PMID: 23613869 PMCID: PMC3629063 DOI: 10.1371/journal.pone.0061517] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 03/11/2013] [Indexed: 11/19/2022] Open
Abstract
Nemaline myopathy (NM) is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. Mutations in the skeletal muscle α-actin gene (ACTA1) account for ∼25% of all NM cases and are the most frequent cause of severe forms of NM. So far, the mechanisms underlying muscle weakness in NM patients remain unclear. Additionally, recent Magnetic Resonance Imaging (MRI) studies reported a progressive fatty infiltration of skeletal muscle with a specific muscle involvement in patients with ACTA1 mutations. We investigated strictly noninvasively the gastrocnemius muscle function of a mouse model carrying a mutation in the ACTA1 gene (H40Y). Skeletal muscle anatomy (hindlimb muscles and fat volumes) and energy metabolism were studied using MRI and 31Phosphorus magnetic resonance spectroscopy. Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (from 1–150 Hz) and a fatigue protocol (80 stimuli at 40 Hz). H40Y mice showed a reduction of both absolute (−40%) and specific (−25%) maximal force production as compared to controls. Interestingly, muscle weakness was associated with an improved resistance to fatigue (+40%) and an increased energy cost. On the contrary, the force frequency relationship was not modified in H40Y mice and the extent of fatty infiltration was minor and not different from the WT group. We concluded that the H40Y mouse model does not reproduce human MRI findings but shows a severe muscle weakness which might be related to an alteration of intrinsic muscular properties. The increased energy cost in H40Y mice might be related to either an impaired mitochondrial function or an alteration at the cross-bridges level. Overall, we provided a unique set of anatomic, metabolic and functional biomarkers that might be relevant for monitoring the progression of NM disease but also for assessing the efficacy of potential therapeutic interventions at a preclinical level.
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Affiliation(s)
- Charlotte Gineste
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Yann Le Fur
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Christophe Vilmen
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Arnaud Le Troter
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Emilie Pecchi
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Patrick J. Cozzone
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Edna C. Hardeman
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - David Bendahan
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Julien Gondin
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
- * E-mail:
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15
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Bosma M, Sparks L, Hooiveld G, Jorgensen J, Houten S, Schrauwen P, Kersten S, Hesselink M. Overexpression of PLIN5 in skeletal muscle promotes oxidative gene expression and intramyocellular lipid content without compromising insulin sensitivity. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:844-52. [DOI: 10.1016/j.bbalip.2013.01.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 01/06/2013] [Accepted: 01/10/2013] [Indexed: 12/11/2022]
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16
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Zierler KA, Jaeger D, Pollak NM, Eder S, Rechberger GN, Radner FPW, Woelkart G, Kolb D, Schmidt A, Kumari M, Preiss-Landl K, Pieske B, Mayer B, Zimmermann R, Lass A, Zechner R, Haemmerle G. Functional cardiac lipolysis in mice critically depends on comparative gene identification-58. J Biol Chem 2013; 288:9892-9904. [PMID: 23413028 DOI: 10.1074/jbc.m112.420620] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Efficient catabolism of cellular triacylglycerol (TG) stores requires the TG hydrolytic activity of adipose triglyceride lipase (ATGL). The presence of comparative gene identification-58 (CGI-58) strongly increased ATGL-mediated TG catabolism in cell culture experiments. Mutations in the genes coding for ATGL or CGI-58 in humans cause neutral lipid storage disease characterized by TG accumulation in multiple tissues. ATGL gene mutations cause a severe phenotype especially in cardiac muscle leading to cardiomyopathy that can be lethal. In contrast, CGI-58 gene mutations provoke severe ichthyosis and hepatosteatosis in humans and mice, whereas the role of CGI-58 in muscle energy metabolism is less understood. Here we show that mice lacking CGI-58 exclusively in muscle (CGI-58KOM) developed severe cardiac steatosis and cardiomyopathy linked to impaired TG catabolism and mitochondrial fatty acid oxidation. The marked increase in ATGL protein levels in cardiac muscle of CGI-58KOM mice was unable to compensate the lack of CGI-58. The addition of recombinant CGI-58 to cardiac lysates of CGI-58KOM mice completely reconstituted TG hydrolytic activities. In skeletal muscle, the lack of CGI-58 similarly provoked TG accumulation. The addition of recombinant CGI-58 increased TG hydrolytic activities in control and CGI-58KOM tissue lysates, elucidating the limiting role of CGI-58 in skeletal muscle TG catabolism. Finally, muscle CGI-58 deficiency affected whole body energy homeostasis, which is caused by impaired muscle TG catabolism and increased cardiac glucose uptake. In summary, this study demonstrates that functional muscle lipolysis depends on both CGI-58 and ATGL.
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Affiliation(s)
- Kathrin A Zierler
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Doris Jaeger
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Nina M Pollak
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Sandra Eder
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | | | - Franz P W Radner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Gerald Woelkart
- Department of Pharmacology and Toxicology, University of Graz, 8010 Graz, Austria
| | - Dagmar Kolb
- Center for Medical Research, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria
| | - Albrecht Schmidt
- Department of Cardiology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria
| | - Manju Kumari
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | | | - Burkert Pieske
- Department of Cardiology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria
| | - Bernd Mayer
- Department of Pharmacology and Toxicology, University of Graz, 8010 Graz, Austria
| | - Robert Zimmermann
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.
| | - Guenter Haemmerle
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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