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Chen H, Zhang H, Jia T, Wang Z, Zhu W. Roles of leptin on energy balance and thermoregulation in Eothenomys miletus. Front Physiol 2022; 13:1054107. [PMID: 36589465 PMCID: PMC9800980 DOI: 10.3389/fphys.2022.1054107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/08/2022] [Indexed: 12/23/2022] Open
Abstract
Leptin is a hormone mainly synthesized and secreted by white adipose tissue (WAT), which regulates various physiological processes. To investigate the role of leptin in energy balance and thermoregulation in Eothenomys miletus, voles were randomly divided into leptin-injected and PBS-injected groups and placed at 25°C ± 1°C with a photoperiod of 12 L:12 D. They were housed under laboratory conditions for 28 days and compared in terms of body mass, food intake, water intake, core body temperature, interscapular skin temperature, resting metabolic rate (RMR), nonshivering thermogenesis (NST), liver and brown adipose tissue (BAT) thermogenic activity, and serum hormone levels. The results showed that leptin injection decreased body mass, body fat, food intake, and water intake. But it had no significant effect on carcass protein. Leptin injection increased core body temperature, interscapular skin temperature, resting metabolic rate, non-shivering thermogenesis, mitochondrial protein content and cytochrome C oxidase (COX) activity in liver and brown adipose tissue, uncoupling protein 1 (UCP1) content and thyroxin 5'-deiodinase (T45'-DII) activity in brown adipose tissue significantly. Serum leptin, triiodothyronine (T3), thyrotropin-releasing hormone (TRH) and corticotropin-releasing hormone (CRH) concentrations were also increased significantly. Correlation analysis showed that serum leptin levels were positively correlated with core body temperature, body mass loss, uncoupling protein 1 content, thyroxin 5'-deiodinase activity, nonshivering thermogenesis, and negatively correlated with food intake; thyroxin 5'-deiodinase and triiodothyronine levels were positively correlated, suggesting that thyroxin 5'-deiodinase may play an important role in leptin-induced thermogenesis in brown adipose tissue. In conclusion, our study shows that exogenous leptin is involved in the regulation of energy metabolism and thermoregulation in E. miletus, and thyroid hormone may play an important role in the process of leptin regulating energy balance in E. miletus.
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Affiliation(s)
- Huibao Chen
- Key Laboratory of Ecological Adaptive Evolution and Conservation on Animals-plants in Southwest Mountain Ecosystem of Yunnan Province Higher Institutes College, School of Life Sciences, Yunnan Normal University, Kunming, China
| | - Hao Zhang
- Key Laboratory of Ecological Adaptive Evolution and Conservation on Animals-plants in Southwest Mountain Ecosystem of Yunnan Province Higher Institutes College, School of Life Sciences, Yunnan Normal University, Kunming, China
| | - Ting Jia
- Yunnan College of Business Management, Kunming, China
| | - Zhengkun Wang
- Key Laboratory of Ecological Adaptive Evolution and Conservation on Animals-plants in Southwest Mountain Ecosystem of Yunnan Province Higher Institutes College, School of Life Sciences, Yunnan Normal University, Kunming, China
| | - Wanlong Zhu
- Key Laboratory of Ecological Adaptive Evolution and Conservation on Animals-plants in Southwest Mountain Ecosystem of Yunnan Province Higher Institutes College, School of Life Sciences, Yunnan Normal University, Kunming, China
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy Ministry of Education, Kunming, China
- Key Laboratory of Yunnan Province for Biomass Energy and Environment Biotechnology, Kunming, China
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Grewal S, Gubbi S, Fosam A, Sedmak C, Sikder S, Talluru H, Brown RJ, Muniyappa R. Metabolomic Analysis of the Effects of Leptin Replacement Therapy in Patients with Lipodystrophy. J Endocr Soc 2019; 4:bvz022. [PMID: 32010873 DOI: 10.1210/jendso/bvz022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 11/14/2019] [Indexed: 12/19/2022] Open
Abstract
Context and Objective Leptin treatment has dramatic clinical effects on glucose and lipid metabolism in leptin-deficient patients with lipodystrophy. Further elucidation of metabolic effects of exogenous leptin therapy will shed light on understanding leptin physiology in humans. Our objective was to utilize metabolomic profiling to examine the changes associated with administration of short-term metreleptin therapy in patients with lipodystrophy. Study Design We conducted a pre-post-treatment study in 19 patients (75% female) with varying forms of lipodystrophy (congenital generalized lipodystrophy, n = 10; acquired generalized lipodystrophy, n = 1; familial partial lipodystrophy, n = 8) who received daily subcutaneous metreleptin injections for a period of 16 to 23 weeks. A 3-hour oral glucose tolerance test and body composition measurements were conducted before and after the treatment period, and fasting blood samples were used for metabolomic profiling. The study outcome aimed at measuring changes in physiologically relevant metabolites before and after leptin therapy. Results Metabolomic analysis revealed changes in pathways involving branched-chain amino acid metabolism, fatty acid oxidation, protein degradation, urea cycle, tryptophan metabolism, nucleotide catabolism, vitamin E, and steroid metabolism. Fold changes in pre- to post-treatment metabolite levels indicated increased breakdown of fatty acids, branched chain amino acids proteins, and nucleic acids. Conclusions Leptin replacement therapy has significant effects on important metabolic pathways implicated in patients with lipodystrophy. Continued metabolomic studies may provide further insight into the mechanisms of action of leptin replacement therapy and provide novel biomarkers of lipodystrophy.Abbreviations: 1,5-AG, 1,5-anhydroglucitol; 11βHSD1, 11-β hydroxysteroid dehydrogenase 1; BCAA, branched-chain amino acid; FFA, free fatty acid; GC-MS, gas chromatography mass spectrometry; IDO, indoleamine 2,3-dioxygenase; IFN-γ, interferon-γ; m/z, mass to charge ratio; OGTT, oral glucose tolerance test; TDO, tryptophan 2,3-dioxygenase; TNF-α, tumor necrosis factor-α; UPLC-MS/MS, ultra-performance liquid chromatography-tandem mass spectrometry.
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Affiliation(s)
- Shivraj Grewal
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Sriram Gubbi
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Andin Fosam
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Caroline Sedmak
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Shanaz Sikder
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Harsha Talluru
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Rebecca J Brown
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Ranganath Muniyappa
- Diabetes, Endocrinology, and Obesity Branch, Clinical Endocrinology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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Will K, Kuzinski J, Kalbe C, Palin MF, Rehfeldt C. Effects of leptin and adiponectin on the growth of porcine myoblasts are associated with changes in p44/42 MAPK signaling. Domest Anim Endocrinol 2013; 45:196-205. [PMID: 24209504 DOI: 10.1016/j.domaniend.2013.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 09/13/2013] [Accepted: 09/13/2013] [Indexed: 12/15/2022]
Abstract
We hypothesized that both adiponectin and leptin affect the growth of porcine skeletal muscle cells, with fatty acids acting as modifiers in adipokine action and that both adipokines influence the gene expression of their receptors. Therefore, the objective of this study was to investigate the effects of recombinant adiponectin and leptin on cell number (DNA) and DNA synthesis rate with and without oleic acid supplementation, on cell death, and on key intracellular signaling molecules of proliferating porcine myoblasts in vitro. Moreover, the mRNA expression of genes encoding for the leptin and adiponectin receptors (LEPR, ADIPOR1, ADIPOR2) as affected by leptin or adiponectin was examined. Recombinant porcine adiponectin (40 μg/mL) and leptin (20 ng/mL) increased DNA synthesis rate, measured as [(3)H]-thymidine incorporation (P < 0.01), reduced cell viability in terms of lactate dehydrogenase release (P < 0.05), or lowered DNA content after 24 h (P < 0.05). In adiponectin-treated cultures, oleic acid supplementation increased DNA synthesis rate and reduced cell number in a dose-dependent manner (P < 0.05). Both adiponectin (P = 0.07) and leptin (P < 0.05) induced a transient activation of p44/42 mitogen-activated protein kinase (MAPK) after 15 min, followed by decreases after 60 and 180 min (P < 0.05). Adiponectin tended to increase c-fos activation (P = 0.08) and decreased p53 activation at 180 min (P = 0.03). Both adiponectin and leptin down-regulated the abundance of ADIPOR2 mRNA and, transiently, of LEPR mRNA (P < 0.05). In conclusion, adiponectin and leptin may adversely affect the growth of porcine myoblasts, which is related to p44/42 MAPK signaling and associated with changes in ligand receptor gene expression.
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Affiliation(s)
- K Will
- Institute for Muscle Biology and Growth, Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
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Leptin and leucine synergistically regulate protein metabolism in C2C12 myotubes and mouse skeletal muscles. Br J Nutr 2012; 110:256-64. [PMID: 23211060 DOI: 10.1017/s0007114512004849] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Leucine and leptin play important roles in regulating protein synthesis and degradation in skeletal muscles in vitro and in vivo. However, the objective of the present study was to determine whether leptin and leucine function synergistically in regulating protein metabolism of skeletal muscles. In the in vitro experiment, C2C12 myotubes were cultured for 2 h in the presence of 5 mm-leucine and/or 50 ng/ml of leptin. In the in vivo experiment, C57BL/6 and ob/ob mice were randomly assigned to be fed a non-purified diet supplemented with 3 % L-leucine or 2·04 % L-alanine (isonitrogenous control) for 14 d. Ob/ob mice were injected intraperitoneally with sterile PBS or recombinant mouse leptin (0·1 μg/g body weight) for 14 d. In C57BL/6 mice, dietary leucine supplementation increased (P< 0·05) plasma leptin, leptin receptor expression and protein synthesis in skeletal muscles, but reduced (P< 0·05) plasma urea and protein degradation in skeletal muscles. Dietary leucine supplementation and leptin injection increased the relative weight of the gastrocnemius and soleus muscles in ob/ob mice. Moreover, leucine and leptin treatments stimulated (P< 0·05) protein synthesis and inhibited (P< 0·05) protein degradation in C2C12 myotubes and skeletal muscles of ob/ob mice. There were interactions (P< 0·05) between the leucine and leptin treatments with regard to protein metabolism in C2C12 myotubes and soleus muscles of ob/ob mice but not in the gastrocnemius muscles of ob/ob mice. Collectively, these results suggest that leptin and leucine synergistically regulate protein metabolism in skeletal muscles both in vitro and in vivo.
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Yang Z, Hulver M, McMillan RP, Cai L, Kershaw EE, Yu L, Xue B, Shi H. Regulation of insulin and leptin signaling by muscle suppressor of cytokine signaling 3 (SOCS3). PLoS One 2012; 7:e47493. [PMID: 23115649 PMCID: PMC3480378 DOI: 10.1371/journal.pone.0047493] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 09/17/2012] [Indexed: 12/24/2022] Open
Abstract
Skeletal muscle resistance to the key metabolic hormones, leptin and insulin, is an early defect in obesity. Suppressor of cytokine signaling 3 (SOCS3) is a major negative regulator of both leptin and insulin signaling, thereby implicating SOCS3 in the pathogenesis of obesity and associated metabolic abnormalities. Here, we demonstrate that SOCS3 mRNA expression is increased in murine skeletal muscle in the setting of diet-induced and genetic obesity, inflammation, and hyperlipidemia. To further evaluate the contribution of muscle SOCS3 to leptin and insulin resistance in obesity, we generated transgenic mice with muscle-specific overexpression of SOCS3 (MCK/SOCS3 mice). Despite similar body weight, MCK/SOCS3 mice develop impaired systemic and muscle-specific glucose homeostasis and insulin action based on glucose and insulin tolerance tests, hyperinsulinemic-euglycemic clamps, and insulin signaling studies. With regards to leptin action, MCK/SOCS3 mice exhibit suppressed basal and leptin-stimulated activity and phosphorylation of alpha2 AMP-activated protein kinase (α2AMPK) and its downstream target, acetyl-CoA carboxylase (ACC). Muscle SOCS3 overexpression also suppresses leptin-regulated genes involved in fatty acid oxidation and mitochondrial function. These studies demonstrate that SOC3 within skeletal muscle is a critical regulator of leptin and insulin action and that increased SOCS may mediate insulin and leptin resistance in obesity.
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Affiliation(s)
- Zhenggang Yang
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
- State Key Laboratory of Infectious Disease Diagnosis and Treatment, First Affiliated Hospital of Zhejiang University, Hang Zhou, China
| | - Matthew Hulver
- Department of Human Nutrition, Foods, and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Ryan P. McMillan
- Department of Human Nutrition, Foods, and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Lingzhi Cai
- Division of Endocrinology, Diabetes, and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Erin E. Kershaw
- Division of Endocrinology, Diabetes, and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Liqing Yu
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States of America
| | - Bingzhong Xue
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Hang Shi
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
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Liu P, Hu Y, Grossmann R, Zhao R. In ovo leptin administration accelerates post-hatch muscle growth and changes myofibre characteristics, gene expression and enzymes activity in broiler chickens. J Anim Physiol Anim Nutr (Berl) 2012; 97:887-95. [PMID: 22853698 DOI: 10.1111/j.1439-0396.2012.01334.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To evaluate the effect of maternal leptin on muscle growth, we injected 0 μg (control, CON), 0.5 μg (low leptin dose, LL) or 5.0 μg (high leptin dose, HL) of recombinant murine leptin dissolved in 100 μl of PBS into the albumen of broiler eggs prior to incubation. The newly hatched chicks were all raised under the same conditions until 21 days of age (D21), when body weight was measured and samples of gastrocnemius muscle were collected and weighed. Myosin ATPase staining was applied to identify myofibre types and measure the cross-sectional area (CSA) of myofibres. Real-time PCR was performed to quantify leptin receptor (LEPR), insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), growth hormone receptor (GHR) and myostatin (MSTN) mRNA expression in the gastrocnemius muscle. The activity of calpains (CAPNs) in the gastrocnemius muscle was measured using a quantitative fluorescence detection kit. Male chickens treated with both high and low doses of leptin had significantly higher (p < 0.05) body weight on D21. The high leptin significantly increased the CSA (p < 0.05) of gastrocnemius muscle in male chickens, which coincided with a 93% increase (p < 0.05) in IGF-1 mRNA expression. Likewise, the LL dose increased the weight of gastrocnemius muscle in male chickens (p < 0.05), which was accompanied by a 41% down-regulation (p < 0.05) of MSTN mRNA expression and a decreased activity of CAPNs. However, all these changes were not observed in female chickens. The proportion of myofibre types did not altered. No significant change was detected for LEPR and GHR mRNA expression. These results indicate that in ovo leptin treatment affects skeletal muscle growth in chickens in a dose-dependent and sex-specific manner. The altered expression of IGF-1, MSTN mRNA and activity of CAPNs in skeletal muscle may be responsible for such effects.
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Affiliation(s)
- P Liu
- Key Laboratory of Animal Physiology and Biochemistry, Nanjing Agricultural University, Nanjing, China Key Laboratory of Poultry Heredity and Breeding, Institute of Poultry Science of Jiangsu Province, Yangzhou, Jiangsu, China Department of Functional Genomics and Bioregulation, Institute of Animal Genetics, FLI, Mariensee, Neustadt, Germany
| | - Y Hu
- Key Laboratory of Animal Physiology and Biochemistry, Nanjing Agricultural University, Nanjing, China Key Laboratory of Poultry Heredity and Breeding, Institute of Poultry Science of Jiangsu Province, Yangzhou, Jiangsu, China Department of Functional Genomics and Bioregulation, Institute of Animal Genetics, FLI, Mariensee, Neustadt, Germany
| | - R Grossmann
- Key Laboratory of Animal Physiology and Biochemistry, Nanjing Agricultural University, Nanjing, China Key Laboratory of Poultry Heredity and Breeding, Institute of Poultry Science of Jiangsu Province, Yangzhou, Jiangsu, China Department of Functional Genomics and Bioregulation, Institute of Animal Genetics, FLI, Mariensee, Neustadt, Germany
| | - R Zhao
- Key Laboratory of Animal Physiology and Biochemistry, Nanjing Agricultural University, Nanjing, China Key Laboratory of Poultry Heredity and Breeding, Institute of Poultry Science of Jiangsu Province, Yangzhou, Jiangsu, China Department of Functional Genomics and Bioregulation, Institute of Animal Genetics, FLI, Mariensee, Neustadt, Germany
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7
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Effects of leptin and adiponectin on proliferation and protein metabolism of porcine myoblasts. Histochem Cell Biol 2012; 138:271-87. [DOI: 10.1007/s00418-012-0949-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2012] [Indexed: 02/01/2023]
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Mofarrahi M, Hussain SNA. Expression and functional roles of angiopoietin-2 in skeletal muscles. PLoS One 2011; 6:e22882. [PMID: 21829546 PMCID: PMC3146511 DOI: 10.1371/journal.pone.0022882] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 07/06/2011] [Indexed: 12/18/2022] Open
Abstract
Background Angiopoietin-1 (ANGPT1) and angiopoietin-2 (ANGPT2) are angiogenesis factors that modulate endothelial cell differentiation, survival and stability. Recent studies have suggested that skeletal muscle precursor cells constitutively express ANGPT1 and adhere to recombinant ANGPT1 and ANGPT2 proteins. It remains unclear whether or not they also express ANGPT2, or if ANGPT2 regulates the myogenesis program of muscle precursors. In this study, ANGPT2 regulatory factors and the effects of ANGPT2 on proliferation, migration, differentiation and survival were identified in cultured primary skeletal myoblasts. The cellular networks involved in the actions of ANGPT2 on skeletal muscle cells were also analyzed. Methodology/Principal Findings Primary skeletal myoblasts were isolated from human and mouse muscles. Skeletal myoblast survival, proliferation, migration and differentiation were measured in-vitro in response to recombinant ANGPT2 protein and to enhanced ANGPT2 expression delivered with adenoviruses. Real-time PCR and ELISA measurements revealed the presence of constitutive ANGPT2 expression in these cells. This expression increased significantly during myoblast differentiation into myotubes. In human myoblasts, ANGPT2 expression was induced by H2O2, but not by TNFα, IL1β or IL6. ANGPT2 significantly enhanced myoblast differentiation and survival, but had no influence on proliferation or migration. ANGPT2-induced survival was mediated through activation of the ERK1/2 and PI-3 kinase/AKT pathways. Microarray analysis revealed that ANGPT2 upregulates genes involved in the regulation of cell survival, protein synthesis, glucose uptake and free fatty oxidation. Conclusion/Significance Skeletal muscle precursors constitutively express ANGPT2 and this expression is upregulated during differentiation into myotubes. Reactive oxygen species exert a strong stimulatory influence on muscle ANGPT2 expression while pro-inflammatory cytokines do not. ANGPT2 promotes skeletal myoblast survival and differentiation. These results suggest that muscle-derived ANGPT2 production may play a positive role in skeletal muscle fiber repair.
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Affiliation(s)
- Mahroo Mofarrahi
- Critical Care and Respiratory Divisions, Royal Victoria Hospital, McGill University Health Centre, and Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Sabah N. A. Hussain
- Critical Care and Respiratory Divisions, Royal Victoria Hospital, McGill University Health Centre, and Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada
- * E-mail:
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Azakir BA, Di Fulvio S, Therrien C, Sinnreich M. Dysferlin interacts with tubulin and microtubules in mouse skeletal muscle. PLoS One 2010; 5:e10122. [PMID: 20405035 PMCID: PMC2853571 DOI: 10.1371/journal.pone.0010122] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 03/11/2010] [Indexed: 12/26/2022] Open
Abstract
Dysferlin is a type II transmembrane protein implicated in surface membrane repair in muscle. Mutations in dysferlin lead to limb girdle muscular dystrophy 2B, Miyoshi Myopathy and distal anterior compartment myopathy. Dysferlin's mode of action is not well understood and only a few protein binding partners have thus far been identified. Using affinity purification followed by liquid chromatography/mass spectrometry, we identified alpha-tubulin as a novel binding partner for dysferlin. The association between dysferlin and alpha-tubulin, as well as between dysferlin and microtubules, was confirmed in vitro by glutathione S-transferase pulldown and microtubule binding assays. These interactions were confirmed in vivo by co-immunoprecipitation. Confocal microscopy revealed that dysferlin and alpha-tubulin co-localized in the perinuclear region and in vesicular structures in myoblasts, and along thin longitudinal structures reminiscent of microtubules in myotubes. We mapped dysferlin's alpha-tubulin-binding region to its C2A and C2B domains. Modulation of calcium levels did not affect dysferlin binding to alpha-tubulin, suggesting that this interaction is calcium-independent. Our studies identified a new binding partner for dysferlin and suggest a role for microtubules in dysferlin trafficking to the sarcolemma.
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Affiliation(s)
- Bilal A. Azakir
- Neuromuscular Research Group, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Sabrina Di Fulvio
- Neuromuscular Research Group, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Christian Therrien
- Neuromuscular Research Group, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Michael Sinnreich
- Neuromuscular Research Group, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
- Neuromuscular Center, Departments of Neurology and Biomedicine, University Hospital Basel, Basel, Switzerland
- * E-mail:
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Mao X, Zeng X, Wang J, Qiao S. Leucine promotes leptin receptor expression in mouse C2C12 myotubes through the mTOR pathway. Mol Biol Rep 2010; 38:3201-6. [PMID: 20151325 DOI: 10.1007/s11033-010-9992-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 02/03/2010] [Indexed: 11/24/2022]
Abstract
Leptin plays a critical role in regulating muscle protein metabolism by binding with leptin receptors in a 1:1 stoichiometry. However, the role for leucine in the regulation of leptin receptor expression in muscle has not been investigated. The present study was conducted to test the hypothesis that leucine regulates leptin receptor levels in C2C12 myotubes. Cells were cultured in the presence of DMEM/F12 medium containing supplemental 0 or 5 mM L: -leucine. Leptin receptor expression by C2C12 myotubes peaked at 2 h post-supplementation. Additionally, leucine stimulated leptin receptor expression at both mRNA and protein levels in a dose-dependent manner. Furthermore, leucine enhanced the phosphorylation of mammalian target of rapamycin (mTOR). Addition of rapamycin (an inhibitor of mTOR) to culture medium completely suppressed leucine-induced activation of mTOR and inhibited leucine-stimulated leptin receptor production. These results indicate that leucine affects leptin receptor expression in muscle cells via the mTOR signaling pathway.
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Affiliation(s)
- Xiangbing Mao
- State Key Laboratory on Animal Nutrition, China Agricultural University, No. 2. Yuanmingyuan West Road, 100193 Beijing, China
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Sáinz N, Rodríguez A, Catalán V, Becerril S, Ramírez B, Gómez-Ambrosi J, Frühbeck G. Leptin administration favors muscle mass accretion by decreasing FoxO3a and increasing PGC-1alpha in ob/ob mice. PLoS One 2009; 4:e6808. [PMID: 19730740 PMCID: PMC2733298 DOI: 10.1371/journal.pone.0006808] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 07/31/2009] [Indexed: 12/26/2022] Open
Abstract
Absence of leptin has been associated with reduced skeletal muscle mass in leptin-deficient ob/ob mice. The aim of our study was to examine the effect of leptin on the catabolic and anabolic pathways regulating muscle mass. Gastrocnemius, extensor digitorum longus and soleus muscle mass as well as fiber size were significantly lower in ob/ob mice compared to wild type littermates, being significantly increased by leptin administration (P<0.001). This effect was associated with an inactivation of the muscle atrophy-related transcription factor forkhead box class O3 (FoxO3a) (P<0.05), and with a decrease in the protein expression levels of the E3 ubiquitin-ligases muscle atrophy F-box (MAFbx) (P<0.05) and muscle RING finger 1 (MuRF1) (P<0.05). Moreover, leptin increased (P<0.01) protein expression levels of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a regulator of muscle fiber type, and decreased (P<0.05) myostatin protein, a negative regulator of muscle growth. Leptin administration also activated (P<0.01) the regulators of cell cycle progression proliferating cell nuclear antigen (PCNA) and cyclin D1, and increased (P<0.01) myofibrillar protein troponin T. The present study provides evidence that leptin treatment may increase muscle mass of ob/ob mice by inhibiting myofibrillar protein degradation as well as enhancing muscle cell proliferation.
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Affiliation(s)
- Neira Sáinz
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Amaia Rodríguez
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Victoria Catalán
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Sara Becerril
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Beatriz Ramírez
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Gema Frühbeck
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- Department of Endocrinology, Clínica Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- * E-mail:
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Akasaka Y, Tsunoda M, Ide T, Murakami K. Chronic leptin treatment stimulates lipid oxidation in immortalized and primary mouse skeletal muscle cells. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:103-9. [PMID: 19103304 DOI: 10.1016/j.bbalip.2008.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 11/07/2008] [Accepted: 11/25/2008] [Indexed: 10/21/2022]
Abstract
Leptin administration enhances lipid oxidation in skeletal muscle. Nevertheless, direct and chronic effect of leptin has not been well characterized. Here, we measured the effect of leptin on skeletal muscles and their signaling pathways using differentiated C(2)C(12) myotubes and primary myotube cultures. Differentiated myotubes expressed both the short and long forms of leptin receptors. Leptin increased lipid oxidation in myotubes in a concentration- and time-dependent manner, with significant induction of lipid oxidation occurring after 6 h. Actinomycin D completely blocked leptin-induced lipid oxidation. Leptin significantly increased phosphorylation of JAK2 and STAT3 in myotubes, and leptin-induced lipid oxidation was abolished by treatment with a JAK2 inhibitor or STAT3 siRNA. We then used mouse myotubes to measure these effects under physiological conditions. Leptin increased lipid oxidation, which again was blocked by a JAK2 inhibitor and STAT3 siRNA. These results suggest that the JAK2/STAT3 signaling pathway may underlie the chronic effects of leptin on lipid oxidation in skeletal muscles.
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Affiliation(s)
- Yunike Akasaka
- Discovery Research Laboratories, Kyorin Pharmaceutical Co., Ltd., 2399-1 Nogi-machi, Shimotsuga-gun, Tochigi 329-0114, Japan
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Jacobi SK, Gabler NK, Ajuwon KM, Davis JE, Spurlock ME. Adipocytes, myofibers, and cytokine biology: new horizons in the regulation of growth and body composition. J Anim Sci 2007; 84 Suppl:E140-9. [PMID: 16582086 DOI: 10.2527/2006.8413_supple140x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Muscle growth in meat animals is a complex process governed by integrated signals emanating from multiple endocrine and immune cells. A generalized phenomenon among meat animal industries is that animals commonly fail to meet their genetic potential for growth in commercial production settings. Therefore, understanding the impact of stress and disease on muscle growth is essential to improving production efficiency. The adipocyte in particular seems to be well positioned as an interface between energy status and immune function, and may thus influence nutrient partitioning and growth through a combination of signals that influence fat metabolism, glucose uptake, and insulin sensitivity. Adipocytes and myofibers are active participants in the innate immune response, and as such, produce a number of metabolic regulators, including leptin, adiponectin, and proinflammatory cytokines. Specifically, adipocytes and muscle cells respond directly to bacterial lipopolysaccharide (LPS) by producing interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha). However, adipocytes are also the predominant source of the antiinflammatory hormone adiponectin, which regulates the nuclear factor kappa-B transcription factor. The ability to recognize antigens and produce regulatory molecules strategically positions adipocytes and myofibers to regulate growth locally, and to reciprocally regulate metabolism peripherally.
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Affiliation(s)
- S K Jacobi
- Department of Animal Sciences, Center for Comparative Medicine, Purdue University, West Lafayette, IN 47907, USA
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14
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Eguchi M, Shrivastava S, Lyakhovsky N, Kim W, Palanivel R, Sweeney G. Control of fatty acid metabolism by leptin in L6 rat myoblasts is regulated by hyperinsulinemia. J Endocrinol Invest 2007; 30:192-9. [PMID: 17505151 DOI: 10.1007/bf03347424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The development of hypothalamic leptin resistance plays a role in the development of obesity, yet whether peripheral leptin resistance occurs in obesity and diabetes is controversial. Here we investigate whether hyperinsulinemia, as observed during the development of Type 2 diabetes, modifies the effects of leptin on long chain fatty acid metabolism in skeletal muscle cells. We used boron dipyrromethene difluoride (BODIPY)-labeled palmitate to show that leptin (60 nM) caused a time-dependent (0-60 min) increase in fatty acid uptake in L6 myoblasts. Quantitative analysis using 3H-palmitate showed that pre-incubation with insulin (100 nM, 24 h) prevented stimulation of fatty acid uptake by leptin. Insulin pre-treatment also attenuated the ability of leptin to phosphorylate acetyl Co-A carboxylase and increase palmitate oxidation. Suppressor of cytokine-3 (SOCS-3) has been proposed as a possible mediator of insulin-induced leptin resistance. Here we show that treatment of L6 cells with insulin elicited a time-dependent increase in both SOCS-3 mRNA and protein content. In summary, hyperinsulinemia can induce leptin resistance in L6 myoblasts and this may be mediated via a SOCS-3-dependent mechanism.
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Affiliation(s)
- M Eguchi
- Department of Biology, York University, Toronto, Ontario, Canada
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15
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Ramsay TG, Richards MP. Leptin and leptin receptor expression in skeletal muscle and adipose tissue in response to in vivo porcine somatotropin treatment. J Anim Sci 2006; 83:2501-8. [PMID: 16230646 DOI: 10.2527/2005.83112501x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The present study was performed to examine the response of leptin and leptin receptor (Rb) genes to porcine somatotropin (pST) stimuli in finishing pigs. Twelve crossbred barrows (Yorkshire x Landrace) were used in this study. Animals were individually fed a basal diet containing 18% CP, 1.2% lysine, and 3.5 Mcal of DE/kg ad libitum (as-fed basis). At 90 kg, six pigs were treated with daily injections of recombinant pST (10 mg) in sterile bicarbonate buffer, whereas the other six pigs were injected with sterile bicarbonate buffer (controls). With initiation of pST treatment, the quantity of feed offered was 85% of calculated ad libitum intake based on BW and adjusted every 3 d. Diet restriction was designed to correct for the effects of the known inhibition in feed intake because of pST treatment in swine. Animals were maintained on treatment for 2 wk. A blood sample was obtained from each pig on d 14 of treatment, 6 h after pST injection. Tissue samples were collected on d 15, frozen in liquid N2, and stored at -80 degrees C before analysis for mRNA abundance. Total RNA was amplified by reverse transcription (RT) PCR with subsequent quantification of transcripts by capillary electrophoresis with laser-induced fluorescence detection. Samples included outer subcutaneous adipose tissue (OSQ), middle subcutaneous adipose tissue (MSQ), leaf fat (LF), liver, latissimus dorsi (LD), and biceps femoris (BF). Restricted feeding resulted in no change in BW of control pigs, whereas pST treatment increased BW by 6.9 +/- 0.5 kg (P < 0.001). Treatment with pST produced a 12-fold increase in serum ST concentration relative to control pigs (P < 0.002). Serum leptin concentration was increased by 17% in swine treated with pST relative to control pigs (P < 0.011). Leptin mRNA abundance was increased in liver by pST treatment (P < 0.05). Administration of pST decreased leptin Rb (Ob-Rb) mRNA abundance by 27% in liver (P < 0.044) and by 49.5% in OSQ (P < 0.025) relative to controls. The present data suggest that pST does not affect leptin expression independent of dietary intake because the restricted feeding regimen used in the present study precluded detection of major change in leptin gene expression. Changes in Ob-Rb mRNA abundance by pST treatment indicate that ST or the metabolic adaptations to ST have a role in regulating Ob-Rb expression.
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Affiliation(s)
- T G Ramsay
- Growth Biology Laboratory, USDA-ARS, Beltsville, MD 20705, USA.
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Noguchi A, Watanabe N, Fujimaki R, Kitamura T, Hayashizaki Y, Miyaki S, Tezuka K, Hozumi N. Use of the SST-REX method for the identification of genes expressed at the condensation stage of chondrogenic cell line ATDC5. J Bone Miner Metab 2006; 24:153-7. [PMID: 16502123 DOI: 10.1007/s00774-005-0662-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Accepted: 10/11/2005] [Indexed: 10/25/2022]
Abstract
In endochondral ossification, chondrogenesis precedes bone development. Cartilage differentiation is initiated by the formation of chondrogenic cell condensates. Thus, it is essential to investigate genes expressed at the condensation stage for a better understanding of chondrogenesis and ossification. To this end, we constructed a cDNA library from the mRNA fraction derived from a chondrogenic cell line (ATDC5) at the cell condensation stage by using the signal sequence trap by retrovirus-mediated expression (SST-REX) method. We obtained 486 factor (IL-3)-independent clones by screening 5.7 x 10(3) clones. DNA sequencing analysis of the clones identified genes encoding 157 known proteins and 4 novel proteins. These 4 genes encoding novel proteins were expressed not only in chondrogenic ATDC5 cells but also in osteogenic MC3T3-E1 and myogenic C2C12 cells. The mRNA expression level of 1 of the 4 clones increased at the calcification stage of the differentiation of MC3T3-E1 cells. The results demonstrate that the SST-REX method is a useful experimental system to identify genes involved in the complicated mechanisms of bone formation.
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Affiliation(s)
- Atsushi Noguchi
- Research Institute for Biological Sciences, Tokyo University of Science (Rikadai), 2669 Yamazaki, Noda, 278-0022, Japan
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Ceddia RB. Direct metabolic regulation in skeletal muscle and fat tissue by leptin: implications for glucose and fatty acids homeostasis. Int J Obes (Lond) 2005; 29:1175-83. [PMID: 16030519 DOI: 10.1038/sj.ijo.0803025] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In recent years, the adipose tissue has emerged as an important endocrine organ. It is now recognized that besides storing energy the adipocytes also secrete several bioactive peptides, collectively called adipocytokines. Among these adipocytokines, leptin, the product of the ob gene, has been extensively investigated over the last decade. Skeletal muscle and adipose tissue, two major tissues involved in the regulation of glucose and fatty acids metabolism, have been consistently demonstrated to be directly affected by leptin. By binding to its receptors located in skeletal muscle and fat cells, leptin promotes energy dissipation and prevents fatty acid accumulation and 'lipotoxicity' in these tissues. On the other hand, under conditions of peripheral leptin resistance, such as observed in obese humans, the activation of pathways involved in fatty acid oxidation may be impaired. This leads to intracellular accumulation of lipid intermediates and causes insulin resistance. This review examines the metabolic pathways that are directly activated by leptin and how it regulates glucose and fatty acids metabolism in skeletal muscle and fat tissue. Furthermore, the impact of peripheral leptin resistance in these tissues leading to dysfunctional metabolic adaptations is also discussed.
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Affiliation(s)
- R B Ceddia
- Department of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.
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