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Guo Y, Livelo C, Melkani G. Time-restricted feeding regulates lipid metabolism under metabolic challenges. Bioessays 2023; 45:e2300157. [PMID: 37850554 PMCID: PMC10841423 DOI: 10.1002/bies.202300157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/19/2023]
Abstract
Dysregulation of lipid metabolism is a commonly observed feature associated with metabolic syndrome and leads to the development of negative health outcomes such as obesity, diabetes mellitus, non-alcoholic fatty liver disease, or atherosclerosis. Time-restricted feeding/eating (TRF/TRE), an emerging dietary intervention, has been shown to promote pleiotropic health benefits including the alteration of diurnal expression of genes associated with lipid metabolism, as well as levels of lipid species. Although TRF likely induces a response in multiple organs leading to the modulation of lipid metabolism, a majority of the studies related to TRF effects on lipids have focused only on individual tissues, and furthermore there is a lack of insight into potential underlying mechanisms. In this review, we summarize the current insights regarding TRF effects on lipid metabolism and the potential mechanisms in adipose tissue, liver, skeletal muscle, and heart, and conclude by outlining possible avenues for future exploration.
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Affiliation(s)
- Yiming Guo
- Department of Pathology, Division of Molecular and Cellular Pathology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Christopher Livelo
- Department of Pathology, Division of Molecular and Cellular Pathology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Girish Melkani
- Department of Pathology, Division of Molecular and Cellular Pathology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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2
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Kim KH, Jia Z, Snyder M, Chen J, Qiu J, Oprescu SN, Chen X, Syed SA, Yue F, Roseguini BT, Imbalzano AN, Hu C, Kuang S. PRMT5 links lipid metabolism to contractile function of skeletal muscles. EMBO Rep 2023; 24:e57306. [PMID: 37334900 PMCID: PMC10398672 DOI: 10.15252/embr.202357306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023] Open
Abstract
Skeletal muscle plays a key role in systemic energy homeostasis besides its contractile function, but what links these functions is poorly defined. Protein Arginine Methyl Transferase 5 (PRMT5) is a well-known oncoprotein but also expressed in healthy tissues with unclear physiological functions. As adult muscles express high levels of Prmt5, we generated skeletal muscle-specific Prmt5 knockout (Prmt5MKO ) mice. We observe reduced muscle mass, oxidative capacity, force production, and exercise performance in Prmt5MKO mice. The motor deficiency is associated with scarce lipid droplets in myofibers due to defects in lipid biosynthesis and accelerated degradation. Specifically, PRMT5 deletion reduces dimethylation and stability of Sterol Regulatory Element-Binding Transcription Factor 1a (SREBP1a), a master regulator of de novo lipogenesis. Moreover, Prmt5MKO impairs the repressive H4R3 symmetric dimethylation at the Pnpla2 promoter, elevating the level of its encoded protein ATGL, the rate-limiting enzyme catalyzing lipolysis. Accordingly, skeletal muscle-specific double knockout of Pnpla2 and Prmt5 normalizes muscle mass and function. Together, our findings delineate a physiological function of PRMT5 in linking lipid metabolism to contractile function of myofibers.
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Affiliation(s)
- Kun Ho Kim
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
| | - Zhihao Jia
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
| | - Madigan Snyder
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
- Department of Biological SciencesPurdue UniversityWest LafayetteINUSA
| | - Jingjuan Chen
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
| | - Jiamin Qiu
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
| | - Stephanie N Oprescu
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
- Department of Biological SciencesPurdue UniversityWest LafayetteINUSA
| | - Xiyue Chen
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
| | - Sabriya A Syed
- Department of Biochemistry and Molecular PharmacologyUniversity of Massachusetts Medical SchoolWorcesterMAUSA
| | - Feng Yue
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
| | - Bruno T Roseguini
- Department of Health and KinesiologyPurdue UniversityWest LafayetteINUSA
| | - Anthony N Imbalzano
- Department of Biochemistry and Molecular PharmacologyUniversity of Massachusetts Medical SchoolWorcesterMAUSA
| | - Changdeng Hu
- Department of Medicinal Chemistry and Molecular PharmacologyPurdue UniversityWest LafayetteINUSA
- Center for Cancer ResearchPurdue UniversityWest LafayetteINUSA
| | - Shihuan Kuang
- Department of Animal SciencesPurdue UniversityWest LafayetteINUSA
- Center for Cancer ResearchPurdue UniversityWest LafayetteINUSA
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3
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Chambers TL, Stroh AM, Chavez C, Brandt AR, Claiborne A, Fountain WA, Gries KJ, Jones AM, Kuszmaul DJ, Lee GA, Lester BE, Lynch CE, Minchev K, Montenegro CF, Naruse M, Raue U, Trappe TA, Trappe S. Multitissue responses to exercise: a MoTrPAC feasibility study. J Appl Physiol (1985) 2023; 135:302-315. [PMID: 37318985 PMCID: PMC10393343 DOI: 10.1152/japplphysiol.00210.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/05/2023] [Accepted: 06/12/2023] [Indexed: 06/17/2023] Open
Abstract
We assessed the feasibility of the Molecular Transducers of Physical Activity Consortium (MoTrPAC) human adult clinical exercise protocols, while also documenting select cardiovascular, metabolic, and molecular responses to these protocols. After phenotyping and familiarization sessions, 20 subjects (25 ± 2 yr, 12 M, 8 W) completed an endurance exercise bout (n = 8, 40 min cycling at 70% V̇o2max), a resistance exercise bout (n = 6, ∼45 min, 3 sets of ∼10 repetition maximum, 8 exercises), or a resting control period (n = 6, 40 min rest). Blood samples were taken before, during, and after (10 min, 2 h, and 3.5 h) exercise or rest for levels of catecholamines, cortisol, glucagon, insulin, glucose, free fatty acids, and lactate. Heart rate was recorded throughout exercise (or rest). Skeletal muscle (vastus lateralis) and adipose (periumbilical) biopsies were taken before and ∼4 h following exercise or rest for mRNA levels of genes related to energy metabolism, growth, angiogenesis, and circadian processes. Coordination of the timing of procedural components (e.g., local anesthetic delivery, biopsy incisions, tumescent delivery, intravenous line flushes, sample collection and processing, exercise transitions, and team dynamics) was reasonable to orchestrate while considering subject burden and scientific objectives. The cardiovascular and metabolic alterations reflected a dynamic and unique response to endurance and resistance exercise, whereas skeletal muscle was transcriptionally more responsive than adipose 4 h postexercise. In summary, the current report provides the first evidence of protocol execution and feasibility of key components of the MoTrPAC human adult clinical exercise protocols. Scientists should consider designing exercise studies in various populations to interface with the MoTrPAC protocols and DataHub.NEW & NOTEWORTHY This study highlights the feasibility of key aspects of the MoTrPAC adult human clinical protocols. This initial preview of what can be expected from acute exercise trial data from MoTrPAC provides an impetus for scientists to design exercise studies to interlace with the rich phenotypic and -omics data that will populate the MoTrPAC DataHub at the completion of the parent protocol.
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Affiliation(s)
- Toby L Chambers
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Andrew M Stroh
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Clarisa Chavez
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Anna R Brandt
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Alex Claiborne
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - William A Fountain
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Kevin J Gries
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Andrew M Jones
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Dillon J Kuszmaul
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Gary A Lee
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Bridget E Lester
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Colleen E Lynch
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Kiril Minchev
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | | | - Masatoshi Naruse
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Ulrika Raue
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Todd A Trappe
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
| | - Scott Trappe
- Human Performance Laboratory, Ball State University, Muncie, Indiana, United States
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Xu M, Chen X, Yu Z, Li X. Receptors that bind to PEDF and their therapeutic roles in retinal diseases. Front Endocrinol (Lausanne) 2023; 14:1116136. [PMID: 37139333 PMCID: PMC10149954 DOI: 10.3389/fendo.2023.1116136] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 04/04/2023] [Indexed: 05/05/2023] Open
Abstract
Retinal neovascular, neurodegenerative, and inflammatory diseases represented by diabetic retinopathy are the main types of blinding eye disorders that continually cause the increased burden worldwide. Pigment epithelium-derived factor (PEDF) is an endogenous factor with multiple effects including neurotrophic activity, anti-angiogenesis, anti-tumorigenesis, and anti-inflammatory activity. PEDF activity depends on the interaction with the proteins on the cell surface. At present, seven independent receptors, including adipose triglyceride lipase, laminin receptor, lipoprotein receptor-related protein, plexin domain-containing 1, plexin domain-containing 2, F1-ATP synthase, and vascular endothelial growth factor receptor 2, have been demonstrated and confirmed to be high affinity receptors for PEDF. Understanding the interactions between PEDF and PEDF receptors, their roles in normal cellular metabolism and the response the initiate in disease will be accommodating for elucidating the ways in which inflammation, angiogenesis, and neurodegeneration exacerbate disease pathology. In this review, we firstly introduce PEDF receptors comprehensively, focusing particularly on their expression pattern, ligands, related diseases, and signal transduction pathways, respectively. We also discuss the interactive ways of PEDF and receptors to expand the prospective understanding of PEDF receptors in the diagnosis and treatment of retinal diseases.
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Al Saedi A, Debruin DA, Hayes A, Hamrick M. Lipid metabolism in sarcopenia. Bone 2022; 164:116539. [PMID: 36007811 DOI: 10.1016/j.bone.2022.116539] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/10/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022]
Abstract
Sarcopenia is an age-related disease associated with loss of muscle mass and strength. This geriatric syndrome predisposes elderly individuals to a disability, falls, fractures, and death. Fat infiltration in muscle is one of the hallmarks of sarcopenia and aging. Alterations in fatty acid (FA) metabolism are evident in aging, type 2 diabetes, and obesity, with the accumulation of lipids inside muscle cells contributing to muscle insulin resistance and ceramide accumulation. These lipids include diacylglycerol, lipid droplets, intramyocellular lipids, intramuscular triglycerides, and polyunsaturated fatty acids (PUFAs). In this review, we examine the regulation of lipid metabolism in skeletal muscle, including lipid metabolization and storage, intervention, and the types of lipases expressed in skeletal muscle responsible for the breakdown of adipose triglyceride fats. In addition, we address the role of FAs in sarcopenia and the potential benefits of PUFAs.
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Affiliation(s)
- Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia; Institute of Health and Sport (IHeS), Victoria University, Melbourne, VIC, Australia.
| | - Danielle A Debruin
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia; Institute of Health and Sport (IHeS), Victoria University, Melbourne, VIC, Australia
| | - Alan Hayes
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia; Institute of Health and Sport (IHeS), Victoria University, Melbourne, VIC, Australia
| | - Mark Hamrick
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Laney Walker Blvd. CB2915, Augusta, GA 30912, USA
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Zhang L, Li F, Guo Q, Duan Y, Wang W, Yang Y, Yin Y, Gong S, Han M, Yin Y. Balanced branched-chain amino acids modulate meat quality by adjusting muscle fiber type conversion and intramuscular fat deposition in finishing pigs. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:3796-3807. [PMID: 34921408 DOI: 10.1002/jsfa.11728] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/13/2021] [Accepted: 12/18/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Pork is an important food for humans and improving the quality of pork is closely related to human health. This study was designed to investigate the effects of balanced branched-chain amino acid (BCAA)-supplemented protein-restricted diets on meat quality, muscle fiber types, and intramuscular fat (IMF) in finishing pigs. RESULTS The results showed that, compared with the normal protein diet (160 g kg-1 crude protein), the reduced-protein diet (120 g kg-1 crude protein) supplemented with BCAAs to the ratio of 2:1:2 not only had higher average daily gain (P < 0.05) and carcass weight (P < 0.05) but also improved meat tenderness and juiciness by decreasing shear force (P < 0.05) and increasing water-holding capacity (P < 0.05). In particular, this treatment showed higher (P < 0.05) levels of phospho-acetyl-CoA carboxylase (P-ACC) and peroxisome proliferation-activated receptor-γ (PPARγ), and lower (P < 0.05) levels of P-adenosine 5'-monophosphate (AMP)-activated protein kinase (P-AMPK), increasing the composition of IMF and MyHC I (P < 0.05) in the longissimus dorsi muscle (LDM). In terms of health, this group increased eicosapentaenoic acid (EPA) (P < 0.01) and desirable hypocholesterolemic fatty acids (DHFA) (P < 0.05), and decreased atherogenicity (AI) (P < 0.01) and hypercholesterolemic saturated fatty acids (HSFA) (P < 0.05). CONCLUSION Our findings suggest a novel role for a balanced BCAA-supplemented restricted protein (RP) diet in the epigenetic regulation of more tender and healthier pork by increasing IMF deposition and fiber type conversion, providing a cross-regulatory molecular basis for revealing the nutritional regulation network of meat quality. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Lingyu Zhang
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fengna Li
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qiuping Guo
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
| | - Yehui Duan
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
| | - Wenlong Wang
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
| | - Yuhuan Yang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Yunju Yin
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Saiming Gong
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Mengmeng Han
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yulong Yin
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China
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7
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Barrett JS, Whytock KL, Strauss JA, Wagenmakers AJM, Shepherd SO. High intramuscular triglyceride turnover rates and the link to insulin sensitivity: influence of obesity, type 2 diabetes and physical activity. Appl Physiol Nutr Metab 2022; 47:343-356. [PMID: 35061523 DOI: 10.1139/apnm-2021-0631] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large intramuscular triglyceride (IMTG) stores in sedentary, obese individuals have been linked to insulin resistance, yet well-trained athletes exhibit high IMTG levels whilst maintaining insulin sensitivity. Contrary to previous assumptions, it is now known that IMTG content per se does not result in insulin resistance. Rather, insulin resistance is caused, at least in part, by the presence of high concentrations of harmful lipid metabolites, such as diacylglycerols and ceramides in muscle. Several mechanistic differences between obese sedentary individuals and their highly trained counterparts have been identified, which determine the differential capacity for IMTG synthesis and breakdown in these populations. In this review, we first describe the most up-to-date mechanisms by which a low IMTG turnover rate (both breakdown and synthesis) leads to the accumulation of lipid metabolites and results in skeletal muscle insulin resistance. We then explore current and potential exercise and nutritional strategies that target IMTG turnover in sedentary obese individuals, to improve insulin sensitivity. Overall, improving IMTG turnover should be an important component of successful interventions that aim to prevent the development of insulin resistance in the ever-expanding sedentary, overweight and obese populations. Novelty: A description of the most up-to-date mechanisms regulating turnover of the IMTG pool. An exploration of current and potential exercise/nutritional strategies to target and enhance IMTG turnover in obese individuals. Overall, highlights the importance of improving IMTG turnover to prevent the development of insulin resistance.
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Affiliation(s)
- J S Barrett
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - K L Whytock
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - J A Strauss
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - A J M Wagenmakers
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - S O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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8
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Tao L, Zhang H, Wang H, Li L, Huang L, Su F, Yuan X, Luo M, Ge L. Characteristics of lipid droplets and the expression of proteins involved in lipolysis in the murine cervix during mid-pregnancy. Reprod Fertil Dev 2021; 32:967-975. [PMID: 32693909 DOI: 10.1071/rd19425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 05/30/2020] [Indexed: 12/16/2022] Open
Abstract
Lipid droplets (LDs) are reservoirs of arachidonoyl lipids for prostaglandin (PG) E2 synthesis, and progesterone can stimulate PGE2 synthesis; however, the relationship between progesterone and LD metabolism in the murine cervix remains unclear. In the present study we examined LD distribution and changes in the expression of proteins involved in lipolysis and autophagy in the murine cervix during pregnancy, and compared the findings with those in dioestrous mice. During mid-pregnancy, LDs were predominantly distributed in the cervical epithelium. Electron microscopy revealed the transfer of numerous LDs from the basal to apical region in the luminal epithelium, marked catabolism of LDs, an elevated number of LDs and autophagosomes and a higher LD:mitochondrion size ratio in murine cervical epithelial cells (P<0.05). In addition, immunohistochemical and western blotting analyses showed significantly higher cAMP-dependent protein kinase, adipose triglyceride lipase and hormone-sensitive lipase expression, and a higher light chain 3 (LC3) II:LC3I ratio in the stroma and smooth muscles and, particularly, in murine cervical epithelial cells, during mid-pregnancy than late dioestrus. In conclusion, these results suggest that the enhanced lipolysis of LDs and autophagy in murine cervical tissues were closely related to pregnancy and were possibly controlled by progesterone because LD catabolism may be necessary for energy provision and PGE2 synthesis to maintain a closed pregnant cervix.
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Affiliation(s)
- Longlong Tao
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Hongyan Zhang
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Hongmei Wang
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Liuhui Li
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Libo Huang
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Feng Su
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Xuejun Yuan
- College of Life Science, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China
| | - Mingjiu Luo
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China; and Corresponding author. ;
| | - Lijiang Ge
- College of Animal Science and Technology, Shandong Agricultural University, N0.61, Daizong Street, Taian, Shandong Province, 271018, P.R. China; and Corresponding author. ;
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9
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Park SJ, Lee M, Oh DH, Kim JL, Park MR, Kim TG, Kim OK, Lee J. Emblica officinalis and Hordeum vulgare L. Mixture Regulates Lipolytic Activity in Differentiated 3T3-L1 Cells. J Med Food 2021; 24:172-179. [PMID: 33617364 DOI: 10.1089/jmf.2020.4810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In this study, we investigated the lipolytic effects of an Emblica officinalis (Indian gooseberry [IG]) and Hordeum vulgare L. (barley sprout [BP]) mixture on differentiated 3T3-L1 cells. On the ninth day of differentiation, Oil red O staining and Western blotting were performed; additionally, glycerol release and triglyceride (TG), fatty acid (FA), and cyclic adenosine monophosphate (cAMP) levels were measured. Compared to the differentiation-induced control (C) group, the IG and BP mixture inhibited intracellular TG and FA levels by 61.7% and 48.9%, respectively, at a concentration of 200 μg/mL. Moreover, the mixture increased glycerol release and cAMP levels by more than twofold more than those in the C group. Western blotting was performed to confirm the protein expression involved in lipolysis, and the IG and BP mixture was found to significantly increase the protein activities of AMP-activated protein kinase, protein kinase A, and hormone-sensitive lipase compared to those of the C group. Furthermore, the mixture significantly inhibited the protein activities of phosphodiesterase 3B, adipose TG lipase, and perilipin compared to those of the C group at a concentration of 200 μg/mL. We found that the IG and BP mixture activates the cAMP pathway and regulates lipolytic enzymes, which are necessary for lipolysis. In conclusion, our findings suggest that the IG and BP mixture can be potentially developed as a new material for targeting mechanisms underlying lipolysis.
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Affiliation(s)
- Soo-Jeung Park
- Department of Medical Nutrition, Kyung Hee University, Yongin, Korea
| | - Minhee Lee
- Department of Medical Nutrition, Kyung Hee University, Yongin, Korea
| | - Dong Hwan Oh
- Department of Medical Nutrition, Kyung Hee University, Yongin, Korea
| | | | | | | | - Ok-Kyung Kim
- Division of Food and Nutrition and Research Institute for Human Ecology, Chonnam National University, Korea
| | - Jeongmin Lee
- Department of Medical Nutrition, Kyung Hee University, Yongin, Korea
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10
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Recazens E, Mouisel E, Langin D. Hormone-sensitive lipase: sixty years later. Prog Lipid Res 2020; 82:101084. [PMID: 33387571 DOI: 10.1016/j.plipres.2020.101084] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/12/2020] [Accepted: 12/24/2020] [Indexed: 12/19/2022]
Abstract
Hormone-sensitive lipase (HSL) was initially characterized as the hormonally regulated neutral lipase activity responsible for the breakdown of triacylglycerols into fatty acids in adipose tissue. This review aims at providing up-to-date information on structural properties, regulation of expression, activity and function as well as therapeutic potential. The lipase is expressed as different isoforms produced from tissue-specific alternative promoters. All isoforms are composed of an N-terminal domain and a C-terminal catalytic domain within which a regulatory domain containing the phosphorylation sites is embedded. Some isoforms possess additional N-terminal regions. The catalytic domain shares similarities with bacteria, fungus and vascular plant proteins but not with other mammalian lipases. HSL singularity is provided by regulatory and N-terminal domains sharing no homology with other proteins. HSL has a broad substrate specificity compared to other neutral lipases. It hydrolyzes acylglycerols, cholesteryl and retinyl esters among other substrates. A novel role of HSL, independent of its enzymatic function, has recently been described in adipocytes. Clinical studies revealed dysregulations of HSL expression and activity in disorders, such as lipodystrophy, obesity, type 2 diabetes and cancer-associated cachexia. Development of specific inhibitors positions HSL as a pharmacological target for the treatment of metabolic complications.
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Affiliation(s)
- Emeline Recazens
- Institute of Metabolic and Cardiovascular Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm), UMR1297, 31432 Toulouse, France; University of Toulouse, Paul Sabatier University, UMR1297, Toulouse, France
| | - Etienne Mouisel
- Institute of Metabolic and Cardiovascular Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm), UMR1297, 31432 Toulouse, France; University of Toulouse, Paul Sabatier University, UMR1297, Toulouse, France
| | - Dominique Langin
- Institute of Metabolic and Cardiovascular Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm), UMR1297, 31432 Toulouse, France; University of Toulouse, Paul Sabatier University, UMR1297, Toulouse, France; Franco-Czech Laboratory for Clinical Research on Obesity, Third Faculty of Medicine, Prague and Paul Sabatier University, Toulouse, France; Toulouse University Hospitals, Laboratory of Clinical Biochemistry, Toulouse, France.
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11
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The Regulation of Fat Metabolism During Aerobic Exercise. Biomolecules 2020; 10:biom10121699. [PMID: 33371437 PMCID: PMC7767423 DOI: 10.3390/biom10121699] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/09/2020] [Accepted: 12/15/2020] [Indexed: 12/19/2022] Open
Abstract
Since the lipid profile is altered by physical activity, the study of lipid metabolism is a remarkable element in understanding if and how physical activity affects the health of both professional athletes and sedentary subjects. Although not fully defined, it has become clear that resistance exercise uses fat as an energy source. The fatty acid oxidation rate is the result of the following processes: (a) triglycerides lipolysis, most abundant in fat adipocytes and intramuscular triacylglycerol (IMTG) stores, (b) fatty acid transport from blood plasma to muscle sarcoplasm, (c) availability and hydrolysis rate of intramuscular triglycerides, and (d) transport of fatty acids through the mitochondrial membrane. In this review, we report some studies concerning the relationship between exercise and the aforementioned processes also in light of hormonal controls and molecular regulations within fat and skeletal muscle cells.
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12
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Nemec M, Vernerová L, Laiferová N, Balážová M, Vokurková M, Kurdiová T, Oreská S, Kubínová K, Klein M, Špiritović M, Tomčík M, Vencovský J, Ukropec J, Ukropcová B. Altered dynamics of lipid metabolism in muscle cells from patients with idiopathic inflammatory myopathy is ameliorated by 6 months of training. J Physiol 2020; 599:207-229. [PMID: 33063873 DOI: 10.1113/jp280468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/13/2020] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Regular exercise improves muscle functional capacity and clinical state of patients with idiopathic inflammatory myopathy (IIM). In our study, we used an in vitro model of human primary muscle cell cultures, derived from IIM patients before and after a 6-month intensive supervised training intervention to assess the impact of disease and exercise on lipid metabolism dynamics. We provide evidence that muscle cells from IIM patients display altered dynamics of lipid metabolism and impaired adaptive response to saturated fatty acid load compared to healthy controls. A 6-month intensive supervised exercise training intervention in patients with IIM mitigated disease effects in their cultured muscle cells, improving or normalizing their capacity to handle lipids. These findings highlight the putative role of intrinsic metabolic defects of skeletal muscle in the pathogenesis of IIM and the positive impact of exercise, maintained in vitro by yet unknown epigenetic mechanisms. ABSTRACT Exercise improves skeletal muscle function, clinical state and quality of life in patients with idiopathic inflammatory myopathy (IIM). Our aim was to identify disease-related metabolic perturbations and the impact of exercise in skeletal muscle cells of IIM patients. Patients underwent a 6-month intensive supervised training intervention. Muscle function, anthropometric and metabolic parameters were examined and muscle cell cultures were established (m. vastus lateralis; Bergström needle biopsy) before and after training from patients and sedentary age/sex/body mass index-matched controls. [14 C]Palmitate was used to determine fat oxidation and lipid synthesis (thin layer chromatography). Cells were exposed to a chronic (3 days) and acute (3 h) metabolic challenge (the saturated fatty acid palmitate, 100 μm). Reduced oxidative (intermediate metabolites, -49%, P = 0.034) and non-oxidative (diglycerides, -38%, P = 0.013) lipid metabolism was identified in palmitate-treated muscle cells from IIM patients compared to controls. Three days of palmitate exposure elicited distinct regulation of oxidative phosphorylation (OxPHOS) complex IV and complex V/ATP synthase (P = 0.012/0.005) and adipose triglyceride lipase in patients compared to controls (P = 0.045) (immunoblotting). Importantly, 6 months of training in IIM patients improved lipid metabolism (CO2 , P = 0.010; intermediate metabolites, P = 0.041) and activation of AMP kinase (P = 0.007), and nearly normalized palmitate-induced changes in OxPHOS proteins in myotubes from IIM patients, in parallel with improvements of patients' clinical state. Myotubes from IIM patients displayed altered dynamics of lipid metabolism and impaired response to metabolic challenge with saturated fatty acid. Our observations suggest that metabolic defects intrinsic to skeletal muscle could represent non-immune pathomechanisms, which can contribute to muscle weakness in IIM. A 6-month training intervention mitigated disease effects in muscle cells in vitro, indicating the existence of epigenetic regulatory mechanisms.
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Affiliation(s)
- M Nemec
- Biomedical Research Centre, Slovak Academy of Sciences, Institute of Experimental Endocrinology, Bratislava, Slovakia
| | - L Vernerová
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - N Laiferová
- Biomedical Research Centre, Slovak Academy of Sciences, Institute of Experimental Endocrinology, Bratislava, Slovakia.,Institute of Pathophysiology, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - M Balážová
- Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - M Vokurková
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - T Kurdiová
- Biomedical Research Centre, Slovak Academy of Sciences, Institute of Experimental Endocrinology, Bratislava, Slovakia
| | - S Oreská
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - K Kubínová
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - M Klein
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - M Špiritović
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic.,Department of Physiotherapy, Faculty of Physical Education and Sport, Charles University, Prague, Czech Republic
| | - M Tomčík
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - J Vencovský
- Institute of Rheumatology and Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - J Ukropec
- Biomedical Research Centre, Slovak Academy of Sciences, Institute of Experimental Endocrinology, Bratislava, Slovakia
| | - B Ukropcová
- Biomedical Research Centre, Slovak Academy of Sciences, Institute of Experimental Endocrinology, Bratislava, Slovakia.,Institute of Pathophysiology, Faculty of Medicine, Comenius University, Bratislava, Slovakia
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13
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Tobias IS, Galpin AJ. Moving human muscle physiology research forward: an evaluation of fiber type-specific protein research methodologies. Am J Physiol Cell Physiol 2020; 319:C858-C876. [DOI: 10.1152/ajpcell.00107.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skeletal muscle is a heterogeneous tissue composed of multiple fiber types that express unique contractile and metabolic properties. While analysis of mixed fiber samples predominates and holds value, increasing attention has been directed toward studying proteins segregated by fiber type, a methodological distinction termed “fiber type-specific.” Fiber type-specific protein studies have the advantage of uncovering key molecular effects that are often missed in mixed fiber homogenate studies but also require greater time and resource-intensive methods, particularly when applied to human muscle. This review summarizes and compares current methods used for fiber type-specific protein analysis, highlighting their advantages and disadvantages for human muscle studies, in addition to recent advances in these techniques. These methods can be grouped into three categories based on the initial processing of the tissue: 1) muscle-specific fiber homogenates, 2) cross sections of fiber bundles, and 3) isolated single fibers, with various subtechniques for performing fiber type identification and protein quantification. The relative implementation for each unique methodological approach is analyzed from 83 fiber type-specific studies of proteins in live human muscle found in the literature to date. These studies have investigated several proteins involved in a wide range of cellular functions that are important to muscle tissue. The second half of this review summarizes key findings from this ensemble of fiber type-specific human protein studies. We highlight examples of where this analytical approach has helped to improve understanding of important physiological topics such as insulin sensitivity, muscle hypertrophy, muscle fatigue, and adaptation to different exercise programs.
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Affiliation(s)
- Irene S. Tobias
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
| | - Andrew J. Galpin
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
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14
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Liu CW, Huang CC, Hsu CF, Li TH, Tsai YL, Lin MW, Tsai HC, Huang SF, Yang YY, Hsieh YC, Lee TY, Tsai CY, Huang YH, Hou MC, Lin HC. SIRT1-dependent mechanisms and effects of resveratrol for amelioration of muscle wasting in NASH mice. BMJ Open Gastroenterol 2020; 7:bmjgast-2020-000381. [PMID: 32371503 PMCID: PMC7228468 DOI: 10.1136/bmjgast-2020-000381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/24/2020] [Accepted: 03/27/2020] [Indexed: 12/21/2022] Open
Abstract
Background In non-alcoholic steatohepatitis (NASH), muscle wasting was an aggravating factor for the progression of hepatic steatosis. This study explores the potential benefits of chronic treatment with resveratrol, a strong activator of SIRT1 on the muscle wasting of NASH mice. Methods In vivo and in vitro study, we evaluate the SIRT1-dependent mechanisms and effects of resveratrol administration for 6 weeks with high-fat-methionine and choline deficient diet-induced NASH mice and palmitate-pretreated C2C12 myoblast cells. Results Resveratrol treatment improved grip strength and muscle mass of limbs, increased running distance and time on exercise wheels in NASH mice. There is a negative correlation between muscular SIRT1 activity and 3-nitrotyrosine levels of NASH and NASH-resv mice. The SIRT1-dependent effect of muscle wasting was associated with the suppression of oxidative stress, upregulation of antioxidants, inhibition of protein degradation, activation of autophagy, suppression of apoptotic activity, upregulation of lipolytic genes and the reduction of fatty infiltration in limb muscles of NASH mice. In vitro, resveratrol alleviated palmitate acid-induced oxidative stress, lipid deposition, autophagy dysfunction, apoptotic signals, and subsequently reduced fusion index and myotube formation of C2C12 cells. The beneficial effects of resveratrol were abolished by EX527. Conclusions Our study suggests that chronic resveratrol treatment is a potential strategy for amelioration of hepatic steatosis and muscle wasting in NASH mouse model.
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Affiliation(s)
- Chih-Wei Liu
- Division of Allergy, Immunology and Rheumatology, Taipei, Taiwan.,Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, Taipei, Taiwan
| | - Chia-Chang Huang
- Institute of Clinical Medicine, Taipei, Taiwan.,Division of Clinical Skills Center, Department of Medical Education, Taipei Veterans General Hospital, Taoyuan, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Chien-Fu Hsu
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Tzu-Hao Li
- Institute of Clinical Medicine, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Allergy, Immunology, and Rheumatology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Yu-Lien Tsai
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Ming-Wei Lin
- Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Institute of Public Health, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Hung-Cheng Tsai
- Division of Allergy, Immunology and Rheumatology, Taipei, Taiwan.,Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shiang-Fen Huang
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Infection Disease, Taipei, Taiwan
| | - Ying-Ying Yang
- Institute of Clinical Medicine, Taipei, Taiwan .,Division of Clinical Skills Center, Department of Medical Education, Taipei Veterans General Hospital, Taoyuan, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Gastroenterology and Hepatology, Taipei, Taiwan
| | - Yun-Cheng Hsieh
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Gastroenterology and Hepatology, Taipei, Taiwan
| | - Tzung-Yan Lee
- Graduate Institute of Traditional Chinese Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Chang-Youh Tsai
- Division of Allergy, Immunology and Rheumatology, Taipei, Taiwan.,Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Yi-Hsiang Huang
- Institute of Clinical Medicine, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Gastroenterology and Hepatology, Taipei, Taiwan
| | - Ming-Chih Hou
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Gastroenterology and Hepatology, Taipei, Taiwan
| | - Han-Chieh Lin
- Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Division of Gastroenterology and Hepatology, Taipei, Taiwan
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15
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Shaw CS, Swinton C, Morales-Scholz MG, McRae N, Erftemeyer T, Aldous A, Murphy RM, Howlett KF. Impact of exercise training status on the fiber type-specific abundance of proteins regulating intramuscular lipid metabolism. J Appl Physiol (1985) 2020; 128:379-389. [PMID: 31917629 DOI: 10.1152/japplphysiol.00797.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Endurance training enhances the capacity for fat oxidation during exercise due to increased utilization of intramuscular lipid (IMCL). This study quantitatively investigated the impact of exercise training status on muscle fiber type-specific abundance of regulatory proteins involved in IMCL utilization. Endurance-trained [n = 7 subjects, peak oxygen consumption (V̇o2peak) 62.6 ± 4.1 (SD) mL·min-1·kg-1] and non-endurance-trained (n = 8 subjects, V̇o2peak 44.9 ± 5.3 mL·min-1·kg-1) young men completed an incremental exercise test to determine maximal fat oxidation (MFO) and maximal oxygen uptake. Fiber type-specific IMCL content and protein abundance were assessed with immunofluorescence microscopy and immunoblot analysis of pooled single muscle fibers and whole muscle. Endurance-trained individuals displayed a higher MFO rate (0.45 ± 0.15 vs. 0.19 ± 0.07 g/min, P < 0.05), a greater proportion of type I muscle fibers, and higher IMCL content compared with untrained individuals (P < 0.05). Adipose triglyceride lipase, hormone-sensitive lipase, perilipin 2, perilipin 5, and hydroxyacyl-coenzyme A dehydrogenase abundances were ~2-3-fold higher in type I muscle fibers compared with type IIa fibers (P < 0.05). Correspondingly, these lipid proteins and oxidative enzymes were higher in endurance-trained individuals when assessed in whole muscle. MFO rate was strongly related to the proportion of type I fibers (R = 0.81, P < 0.01). The abundance of proteins involved in the regulation of IMCL storage and oxidation is highly muscle fiber type specific. The increased capacity for fat oxidation in endurance-trained individuals corresponded with increased IMCL content and elevated abundance of lipolytic and oxidative enzymes in combination with a greater proportion of type I muscle fibers.NEW & NOTEWORTHY We have utilized contemporary techniques to compare the fiber type-specific characteristics of skeletal muscle from endurance-trained athletes and untrained individuals. We show that type I muscle fibers have a coordinated upregulation of proteins controlling intramuscular lipid storage, mobilization, and oxidation. Furthermore, the enhanced capacity for intramuscular lipid storage and utilization in endurance-trained individuals is related to the increased expression of lipid regulatory proteins combined with a greater proportion of type I muscle fibers.
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Affiliation(s)
- C S Shaw
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - C Swinton
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - M G Morales-Scholz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - N McRae
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - T Erftemeyer
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - A Aldous
- Olympic Park Sports Medicine Centre, Melbourne, Victoria, Australia
| | - R M Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - K F Howlett
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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16
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Wilhelmsen A, Mallinson J, Jones R, Cooper S, Taylor T, Tsintzas K. Chronic effects of high-intensity interval training on postprandial lipemia in healthy men. J Appl Physiol (1985) 2019; 127:1763-1771. [PMID: 31622161 DOI: 10.1152/japplphysiol.00131.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The aim of this study was to determine the chronic (≥72 h postexercise) effects of high-intensity interval training (HIIT) on postprandial lipemia and metabolic markers in healthy volunteers. Eight physically active young men (mean ± SD: age 22 ± 3 yr, height 1.77 ± 0.07 m, body mass 67.7 ± 6.2 kg) underwent two 6-h mixed-meal tolerance tests and resting vastus lateralis muscle biopsies before the first session and ≥72 h after the final session of 4 wk of HIIT [16 sessions in total; 10 × 60-s bouts of cycling at 90% maximal oxygen uptake (V̇o2max), interspersed with 60-s intervals at 45% V̇o2max]. Arterialized and deep venous blood samples from across the forearm, brachial artery blood flow measurements, and whole-body indirect calorimetry data were obtained before, and at regular intervals for 6 h after, consumption of a standardized mixed meal. The main findings revealed that, when assessed ≥72 h postexercise, postprandial free fatty acid (FFA) uptake across the forearm was increased in response to exercise training (P = 0.025). However, 4 wk of HIIT did not alter fasting or postprandial circulating triglyceride concentrations or their tissue uptake, despite a 10.2% ± 7.7% improvement in V̇o2max (P = 0.004). Protein content of adipose triglyceride lipase in the vastus lateralis at rest was reduced by 25% ± 21% (P = 0.01). Collectively, these findings suggest that 4 wk of HIIT enhances postprandial clearance of FFA when assessed ≥72 h postexercise but does not confer persisting (training) adaptations in postprandial triglyceridemia.NEW & NOTEWORTHY When assessed ≥72 h after the last exercise session, 4 wk of high-intensity interval training (HIIT) did not improve triglyceridemia but enhanced free fatty acid uptake into muscle with a concurrent reduction in skeletal muscle adipose triglyceride lipase protein content. This suggests that previously reported acute reductions in postprandial triglyceridemia following a single bout of HIIT do not translate to sustained improvements after 4 wk of HIIT, supporting the concept of frequent exercise for the maintenance of lipemic control.
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Affiliation(s)
- Andrew Wilhelmsen
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Joanne Mallinson
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Robert Jones
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Scott Cooper
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Tariq Taylor
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Kostas Tsintzas
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
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17
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Glutathione and Nitric Oxide: Key Team Players in Use and Disuse of Skeletal Muscle. Nutrients 2019; 11:nu11102318. [PMID: 31575008 PMCID: PMC6836164 DOI: 10.3390/nu11102318] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/11/2019] [Accepted: 09/16/2019] [Indexed: 02/07/2023] Open
Abstract
Glutathione (GSH) is the main non-enzymatic antioxidant playing an important role in detoxification, signal transduction by modulation of protein thiols redox status and direct scavenging of radicals. The latter function is not only performed against reactive oxygen species (ROS) but GSH also has a fundamental role in buffering nitric oxide (NO), a physiologically-produced molecule having-multifaceted functions. The efficient rate of GSH synthesis and high levels of GSH-dependent enzymes are characteristic features of healthy skeletal muscle where, besides the canonical functions, it is also involved in muscle contraction regulation. Moreover, NO production in skeletal muscle is a direct consequence of contractile activity and influences several metabolic myocyte pathways under both physiological and pathological conditions. In this review, we will consider the homeostasis and intersection of GSH with NO and then we will restrict the discussion on their role in processes related to skeletal muscle function and degeneration.
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18
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Liu M, Yu X, Lin L, Deng J, Wang K, Xia Y, Tang X, Hong H. ATGL promotes the proliferation of hepatocellular carcinoma cells via the p-AKT signaling pathway. J Biochem Mol Toxicol 2019; 33:e22391. [PMID: 31476254 DOI: 10.1002/jbt.22391] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/30/2019] [Accepted: 08/22/2019] [Indexed: 02/04/2023]
Abstract
Abnormal metabolism, including abnormal lipid metabolism, is a hallmark of cancer cells. Some studies have demonstrated that the lipogenic pathway might promote the development of hepatocellular carcinoma (HCC). However, the role of adipose triglyceride lipase (ATGL) in hepatocellular carcinoma cells has not been elucidated. We evaluated the function of ATGL in hepatocellular carcinoma using methyl azazolyl blue and migration assay through overexpression of ATGL in HepG2 cells. Quantitative reverse-transcription polymerase chain reaction and Western blot analyses were used to assess the mechanisms of ATGL in hepatocellular carcinoma. In the current study, we first constructed and transiently transfected ATGL into hepatocellular carcinoma cells. Secondly, we found that ATGL promoted the proliferation of hepatoma cell lines via upregulating the phosphorylation of AKT, but did not affect the metastatic ability of HCC cells. Moreover, the p-AKT inhibitor significantly eliminated the effect of ATGL on the proliferation of hepatoma carcinoma cells. Taken together, our results indicated that ATGL promotes hepatocellular carcinoma cells proliferation through upregulation of the AKT signaling pathway.
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Affiliation(s)
- Meiling Liu
- Department of Clinical Laboratory, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Xuegao Yu
- Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Liying Lin
- Department of Clinical Laboratory, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Jiankai Deng
- Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Kanglong Wang
- Department of Blood Transfusion, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Yong Xia
- Department of Clinical Laboratory, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Xiaohua Tang
- Department of Clinical Laboratory, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Honghai Hong
- Department of Clinical Laboratory, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.,Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana
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19
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Of mice and men: The physiological role of adipose triglyceride lipase (ATGL). Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:880-899. [PMID: 30367950 PMCID: PMC6439276 DOI: 10.1016/j.bbalip.2018.10.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/18/2018] [Accepted: 10/19/2018] [Indexed: 12/12/2022]
Abstract
Adipose triglyceride lipase (ATGL) has been discovered 14 years ago and revised our view on intracellular triglyceride (TG) mobilization – a process termed lipolysis. ATGL initiates the hydrolysis of TGs to release fatty acids (FAs) that are crucial energy substrates, precursors for the synthesis of membrane lipids, and ligands of nuclear receptors. Thus, ATGL is a key enzyme in whole-body energy homeostasis. In this review, we give an update on how ATGL is regulated on the transcriptional and post-transcriptional level and how this affects the enzymes' activity in the context of neutral lipid catabolism. In depth, we highlight and discuss the numerous physiological functions of ATGL in lipid and energy metabolism. Over more than a decade, different genetic mouse models lacking or overexpressing ATGL in a cell- or tissue-specific manner have been generated and characterized. Moreover, pharmacological studies became available due to the development of a specific murine ATGL inhibitor (Atglistatin®). The identification of patients with mutations in the human gene encoding ATGL and their disease spectrum has underpinned the importance of ATGL in humans. Together, mouse models and human data have advanced our understanding of the physiological role of ATGL in lipid and energy metabolism in adipose and non-adipose tissues, and of the pathophysiological consequences of ATGL dysfunction in mice and men. Summary of mouse models with genetic or pharmacological manipulation of ATGL. Summary of patients with mutations in the human gene encoding ATGL. In depth discussion of the role of ATGL in numerous physiological processes in mice and men.
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20
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An aPPARent Functional Consequence in Skeletal Muscle Physiology via Peroxisome Proliferator-Activated Receptors. Int J Mol Sci 2018; 19:ijms19051425. [PMID: 29747466 PMCID: PMC5983589 DOI: 10.3390/ijms19051425] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/05/2018] [Accepted: 05/08/2018] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle comprises 30–40% of the total body mass and plays a central role in energy homeostasis in the body. The deregulation of energy homeostasis is a common underlying characteristic of metabolic syndrome. Over the past decades, peroxisome proliferator-activated receptors (PPARs) have been shown to play critical regulatory roles in skeletal muscle. The three family members of PPAR have overlapping roles that contribute to the myriad of processes in skeletal muscle. This review aims to provide an overview of the functions of different PPAR members in energy homeostasis as well as during skeletal muscle metabolic disorders, with a particular focus on human and relevant mouse model studies.
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21
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Tan J, Yang H, Fan J, Fan Y, Xiao F. Patients with neutral lipid storage disease with myopathy (NLSDM) in Southwestern China. Clin Neurol Neurosurg 2018. [PMID: 29539587 DOI: 10.1016/j.clineuro.2018.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Neutral lipid storage disease with myopathy (NLSDM) is a rare metabolic myopathy occurring owing to mutations in the patatin like phospholipase domain containing 2 (PNPLA2) gene. Till date, less than 50 patients with PNPLA2 mutations have been reported. In this study, we describe the clinical, pathological, and genetic findings, and muscle magnetic resonance imaging (MRI) changes in four Chinese patients with NLSDM. PATIENTS AND METHODS Peripheral blood smears were stained using Wright's stain. Muscle biopsies, muscle MRI, and sequence analysis of PNPLA2 gene were performed. RESULTS All patients exhibited slowly progressive myopathy during adulthood. Cardiomyopathy, sensorineural hearing loss, hepatic adipose infiltration, and hypertriglyceridemia were observed in some patients. Jordan's anomaly was detected in the blood smears of all patients. Muscle biopsies revealed the presence of massive lipid droplets and rimmed vacuoles in two patients. MR images of the lower lumbar, pelvis, and lower extremities showed the involvement of posterior compartment muscles. The anterior compartment muscles were found to be less affected. Gene analysis for PNPLA2 revealed an identical homozygous mutation c.757 + 1G > T in all patients. CONCLUSION Patients with NLSDM display clinical heterogeneities despite sharing the same mutation (c.757 + 1G > T) of the PNPLA2 gene, may suggest a founder effect in the region.
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Affiliation(s)
- Jiaze Tan
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Haitao Yang
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Jingchuan Fan
- Department of Medical Laboratory Technology, Institute of Life Sciences of Chongqing Medical University, Chongqing 400016, China
| | - Yulan Fan
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Fei Xiao
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China.
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Adipose triglyceride lipase decrement affects skeletal muscle homeostasis during aging through FAs-PPARα-PGC-1α antioxidant response. Oncotarget 2018; 7:23019-32. [PMID: 27056902 PMCID: PMC5029607 DOI: 10.18632/oncotarget.8552] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 03/28/2016] [Indexed: 12/25/2022] Open
Abstract
During aging skeletal muscle shows an accumulation of oxidative damage as well as intramyocellular lipid droplets (IMLDs). However, although the impact of these modifications on muscle tissue physiology is well established, the direct effectors critical for their occurrence are poorly understood. Here we show that during aging the main lipase of triacylglycerols, ATGL, significantly declines in gastrocnemius and its downregulation in C2C12 myoblast leads to the accumulation of lipid droplets. Indeed, we observed an increase of oxidative damage to proteins in terms of carbonylation, S-nitrosylation and ubiquitination that is dependent on a defective antioxidant cell response mediated by ATGL-PPARα-PGC-1α. Overall our findings describe a pivotal role for ATGL in the antioxidant/anti-inflammatory response of muscle cells highlighting this lipase as a therapeutic target for fighting the progressive decline in skeletal muscle mass and strength.
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Watt MJ, Cheng Y. Triglyceride metabolism in exercising muscle. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1250-1259. [PMID: 28652193 DOI: 10.1016/j.bbalip.2017.06.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/15/2017] [Accepted: 06/20/2017] [Indexed: 12/21/2022]
Abstract
Triglycerides are stored within lipid droplets in skeletal muscle and can be hydrolyzed to produce fatty acids for energy production through β-oxidation and oxidative phosphorylation. While there was some controversy regarding the quantitative importance of intramyocellular triglyceride (IMTG) as a metabolic substrate, recent advances in proton magnetic resonance spectroscopy and confocal microscopy support earlier tracer and biopsy studies demonstrating a substantial contribution of IMTG to energy production, particularly during moderate-intensity endurance exercise. This review provides an update on the understanding of IMTG utilization during exercise, with a focus on describing the key regulatory proteins that control IMTG breakdown and how these proteins respond to acute exercise and in the adaptation to exercise training. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Matthew J Watt
- Metabolic Disease and Obesity program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia; Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
| | - Yunsheng Cheng
- Metabolic Disease and Obesity program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia; Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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24
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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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Laurens C, Badin PM, Louche K, Mairal A, Tavernier G, Marette A, Tremblay A, Weisnagel SJ, Joanisse DR, Langin D, Bourlier V, Moro C. G0/G1 Switch Gene 2 controls adipose triglyceride lipase activity and lipid metabolism in skeletal muscle. Mol Metab 2016; 5:527-537. [PMID: 27408777 PMCID: PMC4921782 DOI: 10.1016/j.molmet.2016.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVE Recent data suggest that adipose triglyceride lipase (ATGL) plays a key role in providing energy substrate from triglyceride pools and that alterations of its expression/activity relate to metabolic disturbances in skeletal muscle. Yet little is known about its regulation. We here investigated the role of the protein G0/G1 Switch Gene 2 (G0S2), recently described as an inhibitor of ATGL in white adipose tissue, in the regulation of lipolysis and oxidative metabolism in skeletal muscle. METHODS We first examined G0S2 protein expression in relation to metabolic status and muscle characteristics in humans. We next overexpressed and knocked down G0S2 in human primary myotubes to assess its impact on ATGL activity, lipid turnover and oxidative metabolism, and further knocked down G0S2 in vivo in mouse skeletal muscle. RESULTS G0S2 protein is increased in skeletal muscle of endurance-trained individuals and correlates with markers of oxidative capacity and lipid content. Recombinant G0S2 protein inhibits ATGL activity by about 40% in lysates of mouse and human skeletal muscle. G0S2 overexpression augments (+49%, p < 0.05) while G0S2 knockdown strongly reduces (-68%, p < 0.001) triglyceride content in human primary myotubes and mouse skeletal muscle. We further show that G0S2 controls lipolysis and fatty acid oxidation in a strictly ATGL-dependent manner. These metabolic adaptations mediated by G0S2 are paralleled by concomitant changes in glucose metabolism through the modulation of Pyruvate Dehydrogenase Kinase 4 (PDK4) expression (5.4 fold, p < 0.001). Importantly, downregulation of G0S2 in vivo in mouse skeletal muscle recapitulates changes in lipid metabolism observed in vitro. CONCLUSION Collectively, these data indicate that G0S2 plays a key role in the regulation of skeletal muscle ATGL activity, lipid content and oxidative metabolism.
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Affiliation(s)
- Claire Laurens
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France
| | - Pierre-Marie Badin
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France
| | - Katie Louche
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France
| | - Aline Mairal
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France
| | - Geneviève Tavernier
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France
| | - André Marette
- Department of Medicine, Canada; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada
| | - Angelo Tremblay
- Department of Kinesiology, Canada; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada
| | | | - Denis R Joanisse
- Department of Kinesiology, Canada; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada
| | - Dominique Langin
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France; Toulouse University Hospitals, Department of Clinical Biochemistry, Toulouse, France
| | - Virginie Bourlier
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France
| | - Cedric Moro
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France.
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26
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Søgaard D, Østergård T, Blachnio-Zabielska AU, Baranowski M, Vigelsø AH, Andersen JL, Dela F, Helge JW. Training Does Not Alter Muscle Ceramide and Diacylglycerol in Offsprings of Type 2 Diabetic Patients Despite Improved Insulin Sensitivity. J Diabetes Res 2016; 2016:2372741. [PMID: 27777958 PMCID: PMC5061984 DOI: 10.1155/2016/2372741] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/06/2016] [Accepted: 09/08/2016] [Indexed: 01/08/2023] Open
Abstract
Ceramide and diacylglycerol (DAG) may be involved in the early phase of insulin resistance but data are inconsistent in man. We evaluated if an increase in insulin sensitivity after endurance training was accompanied by changes in these lipids in skeletal muscle. Nineteen first-degree type 2 diabetes Offsprings (Offsprings) (age: 33.1 ± 1.4 yrs; BMI: 26.4 ± 0.4 kg/m2) and sixteen matched Controls (age: 31.3 ± 1.5 yrs; BMI: 25.3 ± 0.7 kg/m2) performed 10 weeks of endurance training three times a week at 70% of VO2max on a bicycle ergometer. Before and after the intervention a hyperinsulinemic-euglycemic clamp and VO2max test were performed and muscle biopsies obtained. Insulin sensitivity was significantly lower in Offsprings compared to control subjects (p < 0.01) but improved in both groups after 10 weeks of endurance training (Off: 17 ± 6%; Con: 12 ± 9%, p < 0.01). The content of muscle ceramide, DAG, and their subspecies were similar between groups and did not change in response to the endurance training except for an overall reduction in C22:0-Cer (p < 0.05). Finally, the intervention induced an increase in AKT protein expression (Off: 27 ± 11%; Con: 20 ± 24%, p < 0.05). This study showed no relation between insulin sensitivity and ceramide or DAG content suggesting that ceramide and DAG are not major players in the early phase of insulin resistance in human muscle.
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Affiliation(s)
- Ditte Søgaard
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Ditte Søgaard:
| | - Torben Østergård
- Department of Endocrinology and Diabetes M, Aarhus University Hospital, Aarhus Sygehus, Aarhus, Denmark
- Department of Internal Medicine, Regional Hospital Viborg, Viborg, Denmark
| | | | - Marcin Baranowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Andreas Hansen Vigelsø
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Flemming Dela
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jørn Wulff Helge
- Xlab, Centre of Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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27
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Turnbull PC, Longo AB, Ramos SV, Roy BD, Ward WE, Peters SJ. Increases in skeletal muscle ATGL and its inhibitor G0S2 following 8 weeks of endurance training in metabolically different rat skeletal muscles. Am J Physiol Regul Integr Comp Physiol 2015; 310:R125-33. [PMID: 26511521 DOI: 10.1152/ajpregu.00062.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 10/21/2015] [Indexed: 12/26/2022]
Abstract
Adipose triglyceride lipase (ATGL) catalyzes the rate-limiting removal of the first fatty acid from a triglyceride. ATGL is activated by comparative gene identification-58 and inhibited by G(0)/G(1) switch gene-2 protein (G0S2). Research in other tissues and cell culture indicates that inhibition is dependent on relative G0S2-to-ATGL protein content. G0S2 may also have several roles within mitochondria; however, this has yet to be observed in skeletal muscle. The purpose of this study was to determine if muscle G0S2 relative to ATGL content would decrease to facilitate intramuscular lipolysis following endurance training. Male Sprague-Dawley rats (n = 10; age 51-53 days old) were progressively treadmill trained at a 10% incline for 8 wk ending with 25 m/min for 1 h compared with control. Sciatic nerve stimulation for hind-limb muscle contraction (and lipolysis) was administered for 30 min to one leg, leaving the opposing leg as a resting control. Soleus (SOL), red gastrocnemius (RG), and white gastrocnemius were excised from both legs following stimulation or control. ATGL protein increased in all trained muscles. Unexpectedly, G0S2 protein was greater in the trained SOL and RG. In RG-isolated mitochondria, G0S2 also increased with training, yet mitochondrial G0S2 content was unaltered with acute contraction; therefore, any role of G0S2 in the mitochondria does not appear to be acutely mediated by content alone. In summary, G0S2 increased with training in oxidative muscles and mitochondria but not following acute contraction, suggesting that inhibition is not through relative G0S2-to-ATGL content but through more complicated intracellular mechanisms.
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Affiliation(s)
- Patrick C Turnbull
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Amanda B Longo
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Sofhia V Ramos
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Brian D Roy
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Wendy E Ward
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Sandra J Peters
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
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28
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Noland RC. Exercise and Regulation of Lipid Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:39-74. [PMID: 26477910 DOI: 10.1016/bs.pmbts.2015.06.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The increased prevalence of hyperlipidemia, hypertriglyceridemia, hypercholesterolemia, and fatty liver disease has provided increasingly negative connotations toward lipids. However, it is important to remember that lipids are essential components supporting life. Lipids are a class of molecules defined by their inherent insolubility in water. In biological systems, lipids are either hydrophobic (containing only polar groups) or amphipathic (possess polar and nonpolar groups). These characteristics lend lipids to be highly diverse with a multitude of functions including hormone and membrane synthesis, involvement in numerous signaling cascades, as well as serving as a source of metabolic fuel supporting energy production. Exercise can induce changes in the lipid composition of membranes that effect fluidity and cellular function, as well as modify the cellular and circulating environment of lipids that regulate signaling cascades. The purpose of this chapter is to focus on lipid utilization as metabolic fuel in response to acute and chronic exercise training. Lipids utilized as an energy source during exercise include circulating fatty acids bound to albumin, triglycerides stored in very-low-density lipoprotein, and intramuscular triglyceride stores. Dynamic changes in these lipid pools during and after exercise are discussed, as well as key factors that may be responsible for regulating changes in fat oxidation in response to varying exercise conditions.
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Affiliation(s)
- Robert C Noland
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, USA.
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29
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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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30
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Turnbull PC, Ramos SV, MacPherson REK, Roy BD, Peters SJ. Characterization of lipolytic inhibitor G(0)/G(1) switch gene-2 protein (G0S2) expression in male Sprague-Dawley rat skeletal muscle compared to relative content of adipose triglyceride lipase (ATGL) and comparitive gene identification-58 (CGI-58). PLoS One 2015; 10:e0120136. [PMID: 25811590 PMCID: PMC4374944 DOI: 10.1371/journal.pone.0120136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 02/04/2015] [Indexed: 01/01/2023] Open
Abstract
The rate-limiting enzyme in lipolysis, adipose triglyceride lipase (ATGL), is activated by comparative gene identification-58 (CGI-58) and inhibited by the G(0)/G(1) switch gene-2 (G0S2) protein. It is speculated that inhibition of ATGL is through a dose dependent manner of relative G0S2 protein content. There is little work examining G0S2 expression in lipolytic tissues, and the relative expression across oxidative tissues such as skeletal muscle has not yet been described. Three muscles, soleus (SOL), red gastrocnemius (RG), and white gastrocnemius (WG) were excised from 57-day old male Sprague-Dawley rats (n = 9). QRT-PCR was used for mRNA analysis, and western blotting was conducted to determine protein content. ATGL and G0S2 protein content were both greatest in the lipolytic SOL, with the least amount of both ATGL and G0S2 protein content found in the WG. CGI-58 protein content however did not mirror ATGL and G0S2 protein content, since the RG had the greatest CGI-58 protein content when compared to the SOL and WG. When comparing our tissues based on CGI-58-to-ATGL ratio and G0S2-to-ATGL ratio, it was discovered that contrary to oxidative demand, the glycolytic WG had the greatest activator CGI-58-to-ATGL ratio with the oxidative SOL having the least, and no differences in G0S2-to-ATGL across the three muscle types. These data suggest that the content of G0S2 relative to the lipase in skeletal muscle would not predict lipolytic potential.
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Affiliation(s)
- Patrick C. Turnbull
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, Ontario, Canada
| | - Sofhia V. Ramos
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, Ontario, Canada
| | - Rebecca E. K. MacPherson
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, Ontario, Canada
| | - Brian D. Roy
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, Ontario, Canada
| | - Sandra J. Peters
- Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, Ontario, Canada
- * E-mail:
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31
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Kaneko K, Kuroda H, Izumi R, Tateyama M, Kato M, Sugimura K, Sakata Y, Ikeda Y, Hirano KI, Aoki M. A novel mutation in PNPLA2 causes neutral lipid storage disease with myopathy and triglyceride deposit cardiomyovasculopathy: A case report and literature review. Neuromuscul Disord 2014; 24:634-41. [DOI: 10.1016/j.nmd.2014.04.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 04/05/2014] [Accepted: 04/09/2014] [Indexed: 12/18/2022]
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32
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Badin PM, Langin D, Moro C. Dynamics of skeletal muscle lipid pools. Trends Endocrinol Metab 2013; 24:607-15. [PMID: 23988586 DOI: 10.1016/j.tem.2013.08.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/22/2013] [Accepted: 08/03/2013] [Indexed: 11/20/2022]
Abstract
Intramyocellular triacylglycerol (IMTG) is emerging as an important energy fuel source during muscle contraction and are adaptively increased in response to exercise, without adverse physiological effects. Paradoxically, elevated IMTG content in obese and type 2 diabetics has been linked to insulin resistance, highlighting the importance of IMTG pools in physiology and pathology. Two separate views suggest that IMTG dynamics are determinant for skeletal muscle fat oxidation, and that disruption of IMTG dynamics facilitates the accumulation of lipotoxic intermediates such as diacylglycerols and ceramides that interfere with insulin signaling. Thus, understanding the factors that control IMTG dynamics is crucial. Here we discuss recent literature describing the regulation of IMTG pools with a particular emphasis on lipases and lipid droplet (LD)-associated proteins.
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Affiliation(s)
- Pierre-Marie Badin
- Obesity Research Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1048, Institute of Metabolic and Cardiovascular Diseases (I2MC), Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France
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Alsted TJ, Ploug T, Prats C, Serup AK, Høeg L, Schjerling P, Holm C, Zimmermann R, Fledelius C, Galbo H, Kiens B. Contraction-induced lipolysis is not impaired by inhibition of hormone-sensitive lipase in skeletal muscle. J Physiol 2013; 591:5141-55. [PMID: 23878361 DOI: 10.1113/jphysiol.2013.260794] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
In skeletal muscle hormone-sensitive lipase (HSL) has long been accepted to be the principal enzyme responsible for lipolysis of intramyocellular triacylglycerol (IMTG) during contractions. However, this notion is based on in vitro lipase activity data, which may not reflect the in vivo lipolytic activity. We investigated lipolysis of IMTG in soleus muscles electrically stimulated to contract ex vivo during acute pharmacological inhibition of HSL in rat muscles and in muscles from HSL knockout (HSL-KO) mice. Measurements of IMTG are complicated by the presence of adipocytes located between the muscle fibres. To circumvent the problem with this contamination we analysed intramyocellular lipid droplet content histochemically. At maximal inhibition of HSL in rat muscles, contraction-induced breakdown of IMTG was identical to that seen in control muscles (P < 0.001). In response to contractions IMTG staining decreased significantly in both HSL-KO and WT muscles (P < 0.05). In vitro TG hydrolase activity data revealed that adipose triglyceride lipase (ATGL) and HSL collectively account for ∼98% of the TG hydrolase activity in mouse skeletal muscle, other TG lipases accordingly being of negligible importance for lipolysis of IMTG. The present study is the first to demonstrate that contraction-induced lipolysis of IMTG occurs in the absence of HSL activity in rat and mouse skeletal muscle. Furthermore, the results suggest that ATGL is activated and plays a major role in lipolysis of IMTG during muscle contractions.
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Affiliation(s)
- Thomas J Alsted
- B. Kiens: Section of Molecular Physiology, Department of Nutrition, Exercise and Sport, University of Copenhagen, Universitetsparken 13, DK, 2100 Copenhagen, Denmark.
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Bakke SS, Moro C, Nikolić N, Hessvik NP, Badin PM, Lauvhaug L, Fredriksson K, Hesselink MK, Boekschoten MV, Kersten S, Gaster M, Thoresen GH, Rustan AC. Palmitic acid follows a different metabolic pathway than oleic acid in human skeletal muscle cells; lower lipolysis rate despite an increased level of adipose triglyceride lipase. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1323-33. [DOI: 10.1016/j.bbalip.2012.07.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 05/31/2012] [Accepted: 07/03/2012] [Indexed: 01/22/2023]
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Mason RR, Meex RCR, Lee-Young R, Canny BJ, Watt MJ. Phosphorylation of adipose triglyceride lipase Ser(404) is not related to 5'-AMPK activation during moderate-intensity exercise in humans. Am J Physiol Endocrinol Metab 2012; 303:E534-41. [PMID: 22713505 DOI: 10.1152/ajpendo.00082.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Intramyocellular triacylglycerol provides fatty acid substrate for ATP generation in contracting muscle. The protein adipose triglyceride lipase (ATGL) is a key regulator of triacylglycerol lipolysis and whole body energy metabolism at rest and during exercise, and ATGL activity is reported to be enhanced by 5'-AMP-activated protein kinase (AMPK)-mediated phosphorylation at Ser(406) in mice. This is a curious observation, because AMPK activation reduces lipolysis in several cell types. We investigated whether the phosphorylation of ATGL Ser(404) (corresponding to murine Ser(406)) was increased during exercise in human skeletal muscle and with pharmacological AMPK activation in myotubes in vitro. In human experiments, skeletal muscle and venous blood samples were obtained from recreationally active male subjects before and at 5 and 60 min during exercise. ATGL Ser(404) phosphorylation was not increased from rest during exercise, but ATGL Ser(404) phosphorylation correlated with myosin heavy chain 1 expression, suggesting a possible fiber type dependency. ATGL Ser(404) phosphorylation was not related to increases in AMPK activity, and immunoprecipitation experiments indicated no interaction between AMPK and ATGL. Rather, ATGL Ser(404) phosphorylation was associated with protein kinase A (PKA) signaling. ATGL Ser(406) phosphorylation in C(2)C(12) myotubes was unaffected by 5-aminoimidazole-4-carboxaminde-1-β-d-ribofuranoside, an AMPK activator, and the PKA activator forskolin. Our results demonstrate that ATGL Ser(404) phosphorylation is not increased in mixed skeletal muscle during moderate-intensity exercise and that AMPK does not appear to be an activating kinase for ATGL Ser(404/406) in skeletal muscle.
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Affiliation(s)
- Rachael R Mason
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
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Nunes PM, van de Weijer T, Veltien A, Arnts H, Hesselink MKC, Glatz JFC, Schrauwen P, Tack CJ, Heerschap A. Increased intramyocellular lipids but unaltered in vivo mitochondrial oxidative phosphorylation in skeletal muscle of adipose triglyceride lipase-deficient mice. Am J Physiol Endocrinol Metab 2012; 303:E71-81. [PMID: 22496349 DOI: 10.1152/ajpendo.00597.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Adipose triglyceride lipase (ATGL) is a lipolytic enzyme that is highly specific for triglyceride hydrolysis. The ATGL-knockout mouse (ATGL(-/-)) accumulates lipid droplets in various tissues, including skeletal muscle, and has poor maximal running velocity and endurance capacity. In this study, we tested whether abnormal lipid accumulation in skeletal muscle impairs mitochondrial oxidative phosphorylation, and hence, explains the poor muscle performance of ATGL(-/-) mice. In vivo ¹H magnetic resonance spectroscopy of the tibialis anterior of ATGL(-/-) mice revealed that its intramyocellular lipid pool is approximately sixfold higher than in WT controls (P = 0.0007). In skeletal muscle of ATGL(-/-) mice, glycogen content was decreased by 30% (P < 0.05). In vivo ³¹P magnetic resonance spectra of resting muscles showed that WT and ATGL(-/-) mice have a similar energy status: [PCr], [P(i)], PCr/ATP ratio, PCr/P(i) ratio, and intracellular pH. Electrostimulated muscles from WT and ATGL(-/-) mice showed the same PCr depletion and pH reduction. Moreover, the monoexponential fitting of the PCr recovery curve yielded similar PCr recovery times (τPCr; 54.1 ± 6.1 s for the ATGL(-/-) and 58.1 ± 5.8 s for the WT), which means that overall muscular mitochondrial oxidative capacity was comparable between the genotypes. Despite similar in vivo mitochondrial oxidative capacities, the electrostimulated muscles from ATGL(-/-) mice displayed significantly lower force production and increased muscle relaxation time than the WT. These findings suggest that mechanisms other than mitochondrial dysfunction cause the impaired muscle performance of ATGL(-/-) mice.
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Affiliation(s)
- P M Nunes
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Badin PM, Loubière C, Coonen M, Louche K, Tavernier G, Bourlier V, Mairal A, Rustan AC, Smith SR, Langin D, Moro C. Regulation of skeletal muscle lipolysis and oxidative metabolism by the co-lipase CGI-58. J Lipid Res 2012; 53:839-848. [PMID: 22383684 DOI: 10.1194/jlr.m019182] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We investigated here the specific role of CGI-58 in the regulation of energy metabolism in skeletal muscle. We first examined CGI-58 protein expression in various muscle types in mice, and next modulated CGI-58 expression during overexpression and knockdown studies in human primary myotubes and evaluated the consequences on oxidative metabolism. We observed a preferential expression of CGI-58 in oxidative muscles in mice consistent with triacylglycerol hydrolase activity. We next showed by pulse-chase that CGI-58 overexpression increased by more than 2-fold the rate of triacylglycerol (TAG) hydrolysis, as well as TAG-derived fatty acid (FA) release and oxidation. Oppositely, CGI-58 silencing reduced TAG hydrolysis and TAG-derived FA release and oxidation (-77%, P < 0.001), whereas it increased glucose oxidation and glycogen synthesis. Interestingly, modulations of CGI-58 expression and FA release are reflected by changes in pyruvate dehydrogenase kinase 4 gene expression. This regulation involves the activation of the peroxisome proliferator activating receptor-δ (PPARδ) by lipolysis products. Altogether, these data reveal that CGI-58 plays a limiting role in the control of oxidative metabolism by modulating FA availability and the expression of PPARδ-target genes, and highlight an important metabolic function of CGI-58 in skeletal muscle.
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Affiliation(s)
- Pierre-Marie Badin
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Camille Loubière
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Maarten Coonen
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Katie Louche
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Geneviève Tavernier
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Virginie Bourlier
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Aline Mairal
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Arild C Rustan
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Steven R Smith
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital and the Burnham Institute for Medical Research, Winter Park, FL
| | - Dominique Langin
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France
| | - Cedric Moro
- Inserm, 1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Paul Sabatier University, Toulouse, France.
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Overexpression of PGC-1α increases fatty acid oxidative capacity of human skeletal muscle cells. Biochem Res Int 2011; 2012:714074. [PMID: 21904680 PMCID: PMC3166714 DOI: 10.1155/2012/714074] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 06/29/2011] [Indexed: 11/17/2022] Open
Abstract
We investigated the effects of PGC-1α (peroxisome proliferator-activated receptor γ coactivator-1α) overexpression on the oxidative capacity of human skeletal muscle cells ex vivo. PGC-1α overexpression increased the oxidation rate of palmitic acid and mRNA expression of genes regulating lipid metabolism, mitochondrial biogenesis, and function in human myotubes. Basal and insulin-stimulated deoxyglucose uptake were decreased, possibly due to upregulation of PDK4 mRNA. Expression of fast fiber-type gene marker (MHCIIa) was decreased. Compared to skeletal muscle in vivo, PGC-1α overexpression increased expression of several genes, which were downregulated during the process of cell isolation and culturing. In conclusion, PGC-1α overexpression increased oxidative capacity of cultured myotubes by improving lipid metabolism, increasing expression of genes involved in regulation of mitochondrial function and biogenesis, and decreasing expression of MHCIIa. These results suggest that therapies aimed at increasing PGC-1α expression may have utility in treatment of obesity and obesity-related diseases.
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Yao-Borengasser A, Varma V, Coker RH, Ranganathan G, Phanavanh B, Rasouli N, Kern PA. Adipose triglyceride lipase expression in human adipose tissue and muscle. Role in insulin resistance and response to training and pioglitazone. Metabolism 2011; 60:1012-20. [PMID: 21129760 PMCID: PMC3062961 DOI: 10.1016/j.metabol.2010.10.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 10/15/2010] [Accepted: 10/18/2010] [Indexed: 02/06/2023]
Abstract
Adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte and muscle triglyceride hydrolysis, and comparative gene identification-58 (CGI-58) is an essential cofactor. We studied the expression of ATGL and CGI-58 in human adipose and muscle and examined correlations with markers of muscle fatty acid oxidation. Nondiabetic volunteers were studied. Subjects with impaired glucose tolerance were treated with pioglitazone or metformin for 10 weeks. Subjects with normal glucose tolerance underwent a 12-week training program. We examined changes in ATGL and CGI-58 with obesity and insulin resistance, and effects of exercise and pioglitazone. Adipose triglyceride lipase messenger RNA (mRNA) expression showed no correlation with either body mass index or insulin sensitivity index in either adipose or muscle. However, adipose ATGL protein levels were inversely correlated with body mass index (r = -0.64, P < .02) and positively correlated with insulin sensitivity index (r = 0.67, P < .02). In muscle, ATGL mRNA demonstrated a strong positive relationship with carnitine palmitoyltransferase I mRNA (r = 0.82, P < .0001) and the adiponectin receptors AdipoR1 mRNA (r = 0.71, P < .0001) and AdipoR2 mRNA (r = 0.74, P < .0001). Muscle CGI-58 mRNA was inversely correlated with intramyocellular triglyceride in both type 1 (r = -0.35, P < .05) and type 2 (r = -0.40, P < .05) fibers. Exercise training resulted in increased muscle ATGL, and pioglitazone increased adipose ATGL by 31% (P < .05). Pioglitazone also increased ATGL in adipocytes. Adipose ATGL protein is decreased with insulin resistance and obesity; and muscle ATGL mRNA is associated with markers of fatty acid oxidation in muscle, as is CGI-58. The regulation of ATGL and CGI-58 has important implications for the control of lipotoxicity.
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Affiliation(s)
- Aiwei Yao-Borengasser
- Department of Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas 72205
| | - Vijayalakshmi Varma
- Department of Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas 72205
| | - Robert H. Coker
- Department of Geriatrics, University of Arkansas for Medical Sciences, and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas 72205
| | - Gouri Ranganathan
- Department of Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas 72205
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver School of Medicine, Aurora, CO 80045
| | - Bounleut Phanavanh
- Department of Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas 72205
| | - Neda Rasouli
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver School of Medicine, Aurora, CO 80045
| | - Philip A. Kern
- Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center4, University of Kentucky, Lexington, KY 40536
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WEDELLOVÁ Z, DIETRICH J, ŠIKLOVÁ-VÍTKOVÁ M, KOLOŠTOVÁ K, KOVÁČIKOVÁ M, DUŠKOVÁ M, BROŽ J, VEDRAL T, ŠTICH V, POLÁK J. Adiponectin Inhibits Spontaneous and Catecholamine-Induced Lipolysis in Human Adipocytes of Non-Obese Subjects Through AMPK-Dependent Mechanisms. Physiol Res 2011; 60:139-48. [DOI: 10.33549/physiolres.931863] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Adiponectin is an adipokine increasing glucose and fatty acid metabolism and improving insulin sensitivity. The aim of this study was to investigate the role of adiponectin in the regulation of adipocyte lipolysis. Human adipocytes isolated from biopsies obtained during surgical operations from 16 non-obese and 17 obese subjects were incubated with 1) human adiponectin (20 µg/ml) or 2) 0.5 mM AICAR – activator of AMPK (adenosine monophosphate activated protein kinase). Following these incubations, isoprenaline was added (10-6 M) to investigate the influence of adiponectin and AICAR on catecholamine-induced lipolysis. Glycerol concentration was measured as lipolysis marker. We observed that adiponectin suppressed spontaneous lipolysis by 21 % and isoprenaline-induced lipolysis by 14 % in non-obese subjects. These effects were not detectable in obese individuals, but statistically significant differences in the effect of adiponectin between obese and non-obese were not revealed by two way ANOVA test. The inhibitory effect of AICAR and adiponectin on lipolysis was reversed by Compound C. Our results suggest, that adiponectin in physiological concentrations inhibits spontaneous as well as catecholamine-induced lipolysis. This effect might be lower in obese individuals and this regulation seems to involve AMPK.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - J. POLÁK
- Department of Sport Medicine, Third Faculty of Medicine, Charles University in Prague, Czech Republic
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Shaw CS, Clark J, Wagenmakers AJM. The effect of exercise and nutrition on intramuscular fat metabolism and insulin sensitivity. Annu Rev Nutr 2010; 30:13-34. [PMID: 20373917 DOI: 10.1146/annurev.nutr.012809.104817] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intramuscular triacylglycerol (IMTG) is both a dynamic fat-storage depot that can expand during periods of elevated lipid availability and a fatty acid source that can be utilized during periods of increased energy expenditure in active individuals. Although many studies have investigated the lifestyle determinants of IMTG content, the results are far from consistent, and studies attempting to unravel the mechanisms behind IMTG metabolism are in their infancy. The limited evidence available suggests that the enzymes responsible for skeletal muscle lipolysis and IMTG synthesis play an important role in determining the fate of fatty acids and therefore the concentration of lipid metabolites and insulin sensitivity of skeletal muscle. This review provides a summary of current knowledge on the effects of acute and chronic exercise as well as energy intake and macronutrient composition of the diet upon the metabolism of IMTG and the implications for metabolic health.
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Affiliation(s)
- Christopher S Shaw
- School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT United Kingdom.
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Coen PM, Dubé JJ, Amati F, Stefanovic-Racic M, Ferrell RE, Toledo FG, Goodpaster BH. Insulin resistance is associated with higher intramyocellular triglycerides in type I but not type II myocytes concomitant with higher ceramide content. Diabetes 2010; 59:80-8. [PMID: 19833891 PMCID: PMC2797948 DOI: 10.2337/db09-0988] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE We tested the primary hypotheses that sphingolipid and diacylglycerol (DAG) content is higher within insulin-resistant muscle and that the association between intramyocellular triglycerides (IMTG) and insulin resistance is muscle fiber type specific. RESEARCH DESIGN AND METHODS A nested case-control analysis was conducted in 22 obese (BMI >30 kg/m(2)) women who were classified as insulin-resistant (IR; n = 12) or insulin-sensitive (IS; n = 10), determined by hyperinsulinemic-euglycemic clamp (>30% greater in IS compared with IR, P < 0.01). Sphingolipid and DAG content was determined by high-performance liquid chromatography-tandem mass spectrometry. Fiber type-specific IMTG content was histologically determined. Gene expression was determined by quantitative PCR. RESULTS Total (555 +/- 53 vs. 293 +/- 54 pmol/mg protein, P = 0.004), saturated (361 +/- 29 vs. 179 +/- 34 pmol/mg protein, P = 0.001), and unsaturated (198 +/- 29 vs. 114 +/- 21 pmol/mg protein, P = 0.034) ceramides were higher in IR compared with IS. DAG concentrations, however, were similar. IMTG content within type I myocytes, but not type II myocytes, was higher in IR compared with IS subjects (P = 0.005). Insulin sensitivity was negatively correlated with IMTG within type I myocytes (R = -0.51, P = 0.026), but not with IMTG within type II myocytes. The proportion of type I myocytes was lower (41 vs. 59%, P < 0.01) in IR subjects. Several genes involved in lipid droplet and fatty acid metabolism were differentially expressed in IR compared with IS subjects. CONCLUSIONS Human skeletal muscle insulin resistance is related to greater IMTG content in type I but not type II myocytes, to greater ceramide content, and to alterations in gene expression associated with lipid metabolism.
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Affiliation(s)
- Paul M. Coen
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John J. Dubé
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Francesca Amati
- Department of Health and Physical Activity, School of Education, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Maja Stefanovic-Racic
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robert E. Ferrell
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Frederico G.S. Toledo
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Bret H. Goodpaster
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Corresponding author: Bret H. Goodpaster,
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Extending the knowledge in histochemistry and cell biology. Histochem Cell Biol 2009; 133:1-40. [PMID: 19946696 DOI: 10.1007/s00418-009-0665-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2009] [Indexed: 01/21/2023]
Abstract
Central to modern Histochemistry and Cell Biology stands the need for visualization of cellular and molecular processes. In the past several years, a variety of techniques has been achieved bridging traditional light microscopy, fluorescence microscopy and electron microscopy with powerful software-based post-processing and computer modeling. Researchers now have various tools available to investigate problems of interest from bird's- up to worm's-eye of view, focusing on tissues, cells, proteins or finally single molecules. Applications of new approaches in combination with well-established traditional techniques of mRNA, DNA or protein analysis have led to enlightening and prudent studies which have paved the way toward a better understanding of not only physiological but also pathological processes in the field of cell biology. This review is intended to summarize articles standing for the progress made in "histo-biochemical" techniques and their manifold applications.
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Schoiswohl G, Schweiger M, Schreiber R, Gorkiewicz G, Preiss-Landl K, Taschler U, Zierler KA, Radner FPW, Eichmann TO, Kienesberger PC, Eder S, Lass A, Haemmerle G, Alsted TJ, Kiens B, Hoefler G, Zechner R, Zimmermann R. Adipose triglyceride lipase plays a key role in the supply of the working muscle with fatty acids. J Lipid Res 2009; 51:490-9. [PMID: 19965578 DOI: 10.1194/jlr.m001073] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FAs are mobilized from triglyceride (TG) stores during exercise to supply the working muscle with energy. Mice deficient for adipose triglyceride lipase (ATGL-ko) exhibit defective lipolysis and accumulate TG in adipose tissue and muscle, suggesting that ATGL deficiency affects energy availability and substrate utilization in working muscle. In this study, we investigated the effect of moderate treadmill exercise on blood energy metabolites and liver glycogen stores in mice lacking ATGL. Because ATGL-ko mice exhibit massive accumulation of TG in the heart and cardiomyopathy, we also investigated a mouse model lacking ATGL in all tissues except cardiac muscle (ATGL-ko/CM). In contrast to ATGL-ko mice, these mice did not accumulate TG in the heart and had normal life expectancy. Exercise experiments revealed that ATGL-ko and ATGL-ko/CM mice are unable to increase circulating FA levels during exercise. The reduced availability of FA for energy conversion led to rapid depletion of liver glycogen stores and hypoglycemia. Together, our studies suggest that ATGL-ko mice cannot adjust circulating FA levels to the increased energy requirements of the working muscle, resulting in an increased use of carbohydrates for energy conversion. Thus, ATGL activity is required for proper energy supply of the skeletal muscle during exercise.
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Schweiger M, Lass A, Zimmermann R, Eichmann TO, Zechner R. Neutral lipid storage disease: genetic disorders caused by mutations in adipose triglyceride lipase/PNPLA2 or CGI-58/ABHD5. Am J Physiol Endocrinol Metab 2009; 297:E289-96. [PMID: 19401457 DOI: 10.1152/ajpendo.00099.2009] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neutral lipid storage disease (NLSD) is a group of autosomal recessive disorders characterized by the excessive accumulation of neutral lipids in multiple tissues. Recently, two genes, adipose triglyceride lipase (ATGL/PNPLA2) and comparative gene identification-58 (CGI-58/ABHD5), have been shown to cause NLSD. ATGL specifically hydrolyzes the first fatty acid from triacylglycerols (TG) and CGI-58/ABHD5 stimulates ATGL activity by a currently unknown mechanism. Mutations in both the ATGL and the CGI-58 genes are associated with systemic TG accumulation, yet the resulting clinical manifestations are not identical. Patients with defective ATGL function suffer from more severe myopathy (NLSDM) than patients with defective CGI-58 function. On the other hand, CGI-58 mutations are always associated with ichthyosis (NLSDI), which was not observed in patients with defective ATGL function. These observations indicate an ATGL-independent function of CGI-58. This review summarizes recent findings with the goal of relating structural variants of ATGL and CGI-58 to functional consequences in lipid metabolism.
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Affiliation(s)
- Martina Schweiger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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46
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Lee K, Shin J, Latshaw J, Suh Y, Serr J. Cloning of adipose triglyceride lipase complementary deoxyribonucleic acid in poultry and expression of adipose triglyceride lipase during development of adipose in chickens. Poult Sci 2009; 88:620-30. [DOI: 10.3382/ps.2008-00265] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Alsted TJ, Nybo L, Schweiger M, Fledelius C, Jacobsen P, Zimmermann R, Zechner R, Kiens B. Adipose triglyceride lipase in human skeletal muscle is upregulated by exercise training. Am J Physiol Endocrinol Metab 2009; 296:E445-53. [PMID: 19106247 DOI: 10.1152/ajpendo.90912.2008] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mobilization of fatty acids from stored triacylglycerol (TG) in adipose tissue and skeletal muscle [intramyocellular triacylglycerol (IMTG)] requires activity of lipases. Although exercise training increases the lipolytic capacity of skeletal muscle, the expression of hormone-sensitive lipase (HSL) is not changed. Recently, adipose triglyceride lipase (ATGL) was identified as a TG-specific lipase in various rodent tissues. To investigate whether human skeletal muscle ATGL protein is regulated by endurance exercise training, 10 healthy young men completed 8 wk of supervised endurance exercise training. Western blotting analysis on lysates of skeletal muscle biopsy samples revealed that exercise training induced a twofold increase in skeletal muscle ATGL protein content. In contrast to ATGL, expression of comparative gene identification 58 (CGI-58), the activating protein of ATGL, and HSL protein was not significantly changed after the training period. The IMTG concentration was significantly decreased by 28% at termination of the training program compared with before. HSL-phoshorylation at Ser(660) was increased, HSL-Ser(659) phosporylation was unchanged, and HSL-phoshorylation at Ser(565) was decreased altogether, indicating an enhanced basal activity of this lipase. No change was found in the expression of diacylglycerol acyl transferase 1 (DGAT1) after training. Inhibition of HSL with a monospecific, small molecule inhibitor (76-0079) and stimulation of ATGL with CGI-58 revealed that significant ATGL activity is present in human skeletal muscle. These results suggest that ATGL in addition to HSL may be important for human skeletal muscle lipolysis.
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Affiliation(s)
- Thomas J Alsted
- University of Copenhagen, The August Krogh Bldg. 13, Universitetsparken, DK, 2100 Copenhagen, Denmark
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48
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Shaw CS, Sherlock M, Stewart PM, Wagenmakers AJM. Adipophilin distribution and colocalization with lipid droplets in skeletal muscle. Histochem Cell Biol 2009; 131:575-81. [PMID: 19169702 DOI: 10.1007/s00418-009-0558-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2009] [Indexed: 01/14/2023]
Abstract
Intramyocellular lipids (IMCL) are stored as discrete lipid droplets which are associated with a number of proteins. The lipid droplet-associated protein adipophilin (the human orthologue of adipose differentiation-related protein) is ubiquitously expressed and is one of the predominant lipid droplet-proteins in skeletal muscle. The aim of this study was to investigate the subcellular distribution of adipophilin in human muscle fibres and to measure the colocalization of adipophilin with IMCL. Muscle biopsies from six lean male cyclists (BMI 23.4 +/- 0.4, aged 31 +/- 2 years, W (max) 346 +/- 8) were stained for myosin heavy chain type 1, IMCL, adipophilin and mitochondria using immunofluorescence and viewed with widefield and confocal fluorescence microscopy. The present study shows that like IMCL, the adipophilin content is ~twofold greater in type I skeletal muscle fibres and is situated in the areas between the mitochondrial network. Colocalization analysis demonstrated that 61 +/- 2% of IMCL contain adipophilin. Although the majority of adipophilin is contained within IMCL, 36 +/- 4% of adipophilin is not associated with IMCL. In conclusion, this study indicates that the IMCL pool is heterogeneous, as the majority but not all IMCL contain adipophilin.
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Affiliation(s)
- Christopher S Shaw
- Exercise Metabolism Research Group, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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49
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State-of-the-art technologies, current opinions and developments, and novel findings: news from the field of histochemistry and cell biology. Histochem Cell Biol 2008; 130:1205-51. [PMID: 18985372 DOI: 10.1007/s00418-008-0535-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2008] [Indexed: 10/25/2022]
Abstract
Investigations of cell and tissue structure and function using innovative methods and approaches have again yielded numerous exciting findings in recent months and have added important data to current knowledge, inspiring new ideas and hypotheses in various fields of modern life sciences. Topics and contents of comprehensive expert reviews covering different aspects in methodological advances, cell biology, tissue function and morphology, and novel findings reported in original papers are summarized in the present review.
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50
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Zimmermann R, Lass A, Haemmerle G, Zechner R. Fate of fat: the role of adipose triglyceride lipase in lipolysis. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:494-500. [PMID: 19010445 DOI: 10.1016/j.bbalip.2008.10.005] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/26/2008] [Accepted: 10/07/2008] [Indexed: 12/21/2022]
Abstract
Lipolysis, the coordinated catabolism of triacylglycerol (TG) stored in cellular lipid droplets, provides fatty acids, di-, and monoglycerides. These products are important energy substrates, precursors for other lipids, or lipid signaling molecules. Following their discovery by Hollenberg, C.H., Raben, M.S., and Astwood, E.B.(1961) and Vaughan, M., Berger, J.E., and Steinberg, D. (1964), hormone-sensitive lipase (HSL) and monoacylglycerol lipase stayed in the focus of research for three decades. Within the last decade, however, it became evident that the lipolytic pathway is incompletely understood. Studies on the regulation of lipolysis and the characterization of HSL-deficient mice indicated that additional previously unrecognized factors that contribute to fat catabolism must exist. This led to the discovery of the perilipin, adipophilin, Tip47 (PAT) family of lipid droplet binding proteins and the identification of a novel TG hydrolase named adipose triglyceride lipase (ATGL). This review focuses on the importance of ATGL as TG lipase within the "lipolytic machinery" and the current knowledge of molecular mechanisms that regulate ATGL activity.
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Affiliation(s)
- Robert Zimmermann
- Insitute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, A-8010 Graz, Austria
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