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Abstract
Since brown adipose tissue (BAT) dissipates energy through UCP1, BAT has garnered attention as a therapeutic intervention for obesity and metabolic diseases including type 2 diabetes. As we better understand the physiological roles of classical brown and beige adipocytes, it is becoming clear that BAT is not simply a heat-generating organ. Increased beige fat mass in response to a variety of external/internal cues is associated with significant improvements in glucose and lipid homeostasis that may not be entirely mediated by UCP1. We aim to discuss recent insights regarding the developmental lineages, molecular regulation, and new functions for brown and beige adipocytes.
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Affiliation(s)
- Shingo Kajimura
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143-0669, USA.
| | - Bruce M Spiegelman
- Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA.
| | - Patrick Seale
- Institute for Diabetes, Obesity, and Metabolism, Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Dong J, Dong Y, Dong Y, Chen F, Mitch WE, Zhang L. Inhibition of myostatin in mice improves insulin sensitivity via irisin-mediated cross talk between muscle and adipose tissues. Int J Obes (Lond) 2015; 40:434-442. [PMID: 26435323 PMCID: PMC4783239 DOI: 10.1038/ijo.2015.200] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 09/04/2015] [Accepted: 09/21/2015] [Indexed: 12/16/2022]
Abstract
Background/Objective In mice, a high fat diet (HFD) induces obesity, insulin resistance and myostatin production. We tested whether inhibition of myostatin in mice can reverse these HFD-induced abnormalities. Subjects/Methods C57BL/6 mice were fed a HFD for 16 weeks including the final 4 weeks some mice were treated with an anti-myostatin peptibody. Body composition, the respiratory exchange ratio plus glucose and insulin tolerance tests were examined. Myostatin knock down in C2C12 cells was performed using ShRNA lentivirus. Adipose tissue-derived stem cells were cultured to measure their reponses to conditioned media from C2C12 cells lacking myostatin, or to recombinant myostatin or Irisin. Isolated peritoneal macrophages were treated with myostatin or Irisin to determine if myostatin or Irisin induce inflammatory mechanisms. Results In HFD-fed mice, peptibody treatment stimulated muscle growth and improved insulin resistance. The improved glucose and insulin tolerances were confirmed when we found increased muscle expression of p-Akt and the glucose transporter, Glut4. In mice fed the HFD, the peptibody suppressed macrophage infiltration and the expression of proinflammatory cytokines in both muscle and adipocytes. Inhibition of myostatin caused the conversion of white (WAT) to brown adipose tissue (BAT) while stimulating fatty acid oxidation and increasing energy expenditure. The related mechanism is a muscle-to-fat cross talk mediated by Irisin. Myostatin inhibition increased PGC-1α expression and Irisin production in muscle. Irisin then stimulated WAT browning. Irisin also suppresses inflammation and stimulates macrophage polarization from M1 to M2 types. Concusion these results uncover a metabolic pathway from an increase in myostatin that suppresses Irisin leading to activation of inflammatory cytokines and insulin resistance. Thus, myostatin is a potential therapeutic target to treat insulin resistance of type II diabetes as well as the shortage of brown/beige fat in obesity.
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Affiliation(s)
- Jiangling Dong
- College of Life Sciences, Sichuan University, Chengdu 610065, China.,Baylor College of Medicine, Nephrology Division, Houston, TX, 77030
| | - Yanjun Dong
- Baylor College of Medicine, Nephrology Division, Houston, TX, 77030.,Beijing Institutes of Heart, Lung, and Blood Vessel Diseases, An Zhen Hospital Affiliated to Capital Medical University, Beijing, 100029, China
| | - Yanlan Dong
- Baylor College of Medicine, Nephrology Division, Houston, TX, 77030
| | - Fang Chen
- College of Life Sciences, Sichuan University, Chengdu 610065, China
| | - William E Mitch
- Baylor College of Medicine, Nephrology Division, Houston, TX, 77030
| | - Liping Zhang
- Baylor College of Medicine, Nephrology Division, Houston, TX, 77030
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53
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Moyer AL, Wagner KR. Mammalian Mss51 is a skeletal muscle-specific gene modulating cellular metabolism. J Neuromuscul Dis 2015; 2:371-385. [PMID: 26634192 PMCID: PMC4664537 DOI: 10.3233/jnd-150119] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND The transforming growth factor β (TGF-β) signaling pathways modulate skeletal muscle growth, regeneration, and cellular metabolism. Several recent gene expression studies have shown that inhibition of myostatin and TGF-β1 signaling consistently leads to a significant reduction in expression of Mss51, also named Zmynd17. The function of mammalian Mss51 is unknown although a putative homolog in yeast is a mitochondrial translational activator. OBJECTIVE The objective of this work was to characterize mammalian Mss51. METHODS Quantitative RT-PCR and immunoblot of subcellular fractionation were used to determine expression patterns and localization of Mss51. The CRISPR/Cas9 system was used to reduce expression of Mss51 in C2C12 myoblasts and the function of Mss51 was evaluated in assays of proliferation, differentiation and cellular metabolism. RESULTS Mss51 was predominantly expressed in skeletal muscle and in those muscles dominated by fast-twitch fibers. In vitro, its expression was upregulated upon differentiation of C2C12 myoblasts into myotubes. Expression of Mss51 was modulated in response to altered TGF-β family signaling. In human muscle, Mss51 localized to the mitochondria. Its genetic disruption resulted in increased levels of cellular ATP, β-oxidation, glycolysis, and oxidative phosphorylation. CONCLUSIONS Mss51 is a novel, skeletal muscle-specific gene and a key target of myostatin and TGF-β1 signaling. Unlike myostatin, TGF-β1 and IGF-1, Mss51 does not regulate myoblast proliferation or differentiation. Rather, Mss51 appears to be one of the effectors of these growth factors on metabolic processes including fatty acid oxidation, glycolysis and oxidative phosphorylation.
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Affiliation(s)
- Adam L. Moyer
- The Hugo W. Moser Research Institute, Kennedy Krieger Institute, Baltimore, MD, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Kathryn R. Wagner
- The Hugo W. Moser Research Institute, Kennedy Krieger Institute, Baltimore, MD, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
- Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA
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54
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Brown adipose tissue: a potential target in the fight against obesity and the metabolic syndrome. Clin Sci (Lond) 2015; 129:933-49. [DOI: 10.1042/cs20150339] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BAT (brown adipose tissue) is the main site of thermogenesis in mammals. It is essential to ensure thermoregulation in newborns. It is also found in (some) adult humans. Its capacity to oxidize fatty acids and glucose without ATP production contributes to energy expenditure and glucose homoeostasis. Brown fat activation has thus emerged as an attractive therapeutic target for the treatment of obesity and the metabolic syndrome. In the present review, we integrate the recent advances on the metabolic role of BAT and its relation with other tissues as well as its potential contribution to fighting obesity and the metabolic syndrome.
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55
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Ahima RS, Park HK. Connecting Myokines and Metabolism. Endocrinol Metab (Seoul) 2015; 30:235-45. [PMID: 26248861 PMCID: PMC4595346 DOI: 10.3803/enm.2015.30.3.235] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 06/22/2015] [Accepted: 06/29/2015] [Indexed: 12/20/2022] Open
Abstract
Skeletal muscle is the largest organ of the body in non-obese individuals and is now considered to be an endocrine organ. Hormones (myokines) secreted by skeletal muscle mediate communications between muscle and liver, adipose tissue, brain, and other organs. Myokines affect muscle mass and myofiber switching, and have profound effects on glucose and lipid metabolism and inflammation, thus contributing to energy homeostasis and the pathogenesis of obesity, diabetes, and other diseases. In this review, we summarize recent findings on the biology of myokines and provide an assessment of their potential as therapeutic targets.
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Affiliation(s)
- Rexford S Ahima
- Division of Endocrinology, Diabetes and Metabolism, and the Institute for Diabetes, Obesity and Metabolism, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
| | - Hyeong Kyu Park
- Department of Internal Medicine, Soonchunhyang University College of Medicine, Seoul, Korea
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56
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Sano T, Iwashita M, Nagayasu S, Yamashita A, Shinjo T, Hashikata A, Asano T, Kushiyama A, Ishimaru N, Takahama Y, Nishimura F. Protection from diet-induced obesity and insulin resistance in mice lacking CCL19-CCR7 signaling. Obesity (Silver Spring) 2015; 23:1460-71. [PMID: 26097021 DOI: 10.1002/oby.21127] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/14/2015] [Accepted: 04/04/2015] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Several chemokines play important roles in recruiting the monocyte/macrophage lineage into adipose tissues. We previously found CCL19 was highly expressed in adipocytes cocultured with macrophages stimulated by endotoxin. This study aimed to evaluate the role of CCL19-CCR7 axis on obesity and insulin resistance. METHODS Serum CCL19 concentration was examined in obese model mice challenged by endotoxin. CCL19 receptor-null, Ccr7(-/-), mice and wild-type mice fed a high-fat diet or normal diet were used to investigate the role of CCL19 signals on obesity-associated inflammation. RESULTS CCL19 protein was elevated in the sera of obese model mice challenged by endotoxin. Ccr7(-/-) mice were protected from diet-induced obesity and insulin resistance. The adipose tissue and liver expression of inflammatory genes of Ccr7(-/-) mice was much lower than in diet-induced obese mice. Ccr7(-/-) mice were protected from fatty liver and dyslipidemia and exhibited increased thermogenesis on high-fat feeding. CCL19 attracts activated dendritic cells (DC). The expression of the DC markers, CD11b and 11c, was not observed in the adipose tissues of Ccr7(-/-) mice fed a high-fat diet, which might be closely associated with the protection of these mice from obesity. CONCLUSIONS The CCL19-CCR7 pathway associates with the development of high-fat-induced obesity and insulin resistance.
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Affiliation(s)
- Tomomi Sano
- Department of Dental Science for Health Promotion, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan
| | - Misaki Iwashita
- Section of Periodontology, Kyushu University Faculty of Dental Science, Fukuoka, Japan
| | - Shintaro Nagayasu
- Department of Dental Science for Health Promotion, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan
| | - Akiko Yamashita
- Section of Periodontology, Kyushu University Faculty of Dental Science, Fukuoka, Japan
| | - Takanori Shinjo
- Section of Periodontology, Kyushu University Faculty of Dental Science, Fukuoka, Japan
| | - Atsushi Hashikata
- Department of Dental Science for Health Promotion, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan
| | - Tomoichiro Asano
- Department of Biological Chemistry, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan
| | - Akifumi Kushiyama
- Division of Metabolic Diseases, The Institute for Adult Diseases, Asahi Life Foundation, Tokyo, Japan
| | - Naozumi Ishimaru
- Department of Oral Molecular Pathology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Yousuke Takahama
- Division of Experimental Immunology, Institute for Genome Research, the University of Tokushima, Tokushima, Japan
| | - Fusanori Nishimura
- Section of Periodontology, Kyushu University Faculty of Dental Science, Fukuoka, Japan
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57
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Novel Function of Rev-erbα in Promoting Brown Adipogenesis. Sci Rep 2015; 5:11239. [PMID: 26058812 PMCID: PMC4462032 DOI: 10.1038/srep11239] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 05/14/2015] [Indexed: 12/11/2022] Open
Abstract
Brown adipose tissue is a major thermogenic organ that plays a key role in maintenance of body temperature and whole-body energy homeostasis. Rev-erbα, a ligand-dependent nuclear receptor and transcription repressor of the molecular clock, has been implicated in the regulation of adipogenesis. However, whether Rev-erbα participates in brown fat formation is not known. Here we show that Rev-erbα is a key regulator of brown adipose tissue development by promoting brown adipogenesis. Genetic ablation of Rev-erbα in mice severely impairs embryonic and neonatal brown fat formation accompanied by loss of brown identity. This defect is due to a cell-autonomous function of Rev-erbα in brown adipocyte lineage commitment and terminal differentiation, as demonstrated by genetic loss- and gain-of-function studies in mesenchymal precursors and brown preadipocytes. Moreover, pharmacological activation of Rev-erbα activity promotes, whereas its inhibition suppresses brown adipocyte differentiation. Mechanistic investigations reveal that Rev-erbα represses key components of the TGF-β cascade, an inhibitory pathway of brown fat development. Collectively, our findings delineate a novel role of Rev-erbα in driving brown adipocyte development, and provide experimental evidence that pharmacological interventions of Rev-erbα may offer new avenues for the treatment of obesity and related metabolic disorders.
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58
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Nam D, Guo B, Chatterjee S, Chen MH, Nelson D, Yechoor VK, Ma K. The adipocyte clock controls brown adipogenesis through the TGF-β and BMP signaling pathways. J Cell Sci 2015; 128:1835-47. [PMID: 25749863 PMCID: PMC4446734 DOI: 10.1242/jcs.167643] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 02/25/2015] [Indexed: 01/11/2023] Open
Abstract
The molecular clock is intimately linked to metabolic regulation, and brown adipose tissue plays a key role in energy homeostasis. However, whether the cell-intrinsic clock machinery participates in brown adipocyte development is unknown. Here, we show that Bmal1 (also known as ARNTL), the essential clock transcription activator, inhibits brown adipogenesis to adversely affect brown fat formation and thermogenic capacity. Global ablation of Bmal1 in mice increases brown fat mass and cold tolerance, and adipocyte-selective inactivation of Bmal1 recapitulates these effects and demonstrates its cell-autonomous role in brown adipocyte formation. Further loss- and gain-of-function studies in mesenchymal precursors and committed brown progenitors reveal that Bmal1 inhibits brown adipocyte lineage commitment and terminal differentiation. Mechanistically, Bmal1 inhibits brown adipogenesis through direct transcriptional control of key components of the TGF-β pathway together with reciprocally altered BMP signaling; activation of TGF-β or blockade of BMP pathways suppresses enhanced differentiation in Bmal1-deficient brown adipocytes. Collectively, our study demonstrates a novel temporal regulatory mechanism in fine-tuning brown adipocyte lineage progression to affect brown fat formation and thermogenic regulation, which could be targeted therapeutically to combat obesity.
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Affiliation(s)
- Deokhwa Nam
- Center for Diabetes Research, Department of Medicine, The Methodist Hospital Research Institute, Houston, TX, 77030, USA
| | - Bingyan Guo
- Department of Cardiovascular Medicine, Second Affiliated Hospital, Hebei Medical University, Shijiazhuang, 050017, Hebei, China
| | - Somik Chatterjee
- Center for Diabetes Research, Department of Medicine, The Methodist Hospital Research Institute, Houston, TX, 77030, USA
| | - Miao-Hsueh Chen
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - David Nelson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Vijay K Yechoor
- Diabetes and Endocrinology Research Center, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Ke Ma
- Center for Diabetes Research, Department of Medicine, The Methodist Hospital Research Institute, Houston, TX, 77030, USA
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59
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Abstract
Obesity and its associated metabolic diseases present a major public health problem around the world. The discovery that thermogenic fat is active in adult humans has sparked a renewal of interest in the study of its development and function and in the feasibility of using modulators of thermogenesis to work against obesity. In recent years, it has been shown that there are at least two distinct types of thermogenic fat cells: brown and beige fat. In this review, we discuss the transcriptional mediators of thermogenesis and the signaling molecules that regulate thermogenic cells. We also review the effects of thermogenic fat activation on whole-body metabolic parameters and evaluate the increasing evidence that activating thermogenesis in humans can be a viable method of ameliorating obesity. In these discussions, we highlight targets that can potentially be stimulated or modified in anti-obesity treatments.
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Affiliation(s)
- Margo P Emont
- Life Sciences Institute Department of Molecular and Integrative Physiology University of Michigan, 210 Washtenaw Avenue, LSI, RM5115A, Ann Arbor, Michigan 48109, USA Life Sciences Institute Department of Molecular and Integrative Physiology University of Michigan, 210 Washtenaw Avenue, LSI, RM5115A, Ann Arbor, Michigan 48109, USA
| | - Hui Yu
- Life Sciences Institute Department of Molecular and Integrative Physiology University of Michigan, 210 Washtenaw Avenue, LSI, RM5115A, Ann Arbor, Michigan 48109, USA
| | - Jun Wu
- Life Sciences Institute Department of Molecular and Integrative Physiology University of Michigan, 210 Washtenaw Avenue, LSI, RM5115A, Ann Arbor, Michigan 48109, USA Life Sciences Institute Department of Molecular and Integrative Physiology University of Michigan, 210 Washtenaw Avenue, LSI, RM5115A, Ann Arbor, Michigan 48109, USA
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60
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Zhu Y, Yang R, McLenithan J, Yu D, Wang H, Wang Y, Singh D, Olson J, Sztalryd C, Zhu D, Gong DW. Direct conversion of human myoblasts into brown-like adipocytes by engineered super-active PPARγ. Obesity (Silver Spring) 2015; 23:1014-21. [PMID: 25919922 PMCID: PMC4413469 DOI: 10.1002/oby.21062] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 01/29/2015] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine whether super-activation of PPARγ can reprogram human myoblasts into brown-like adipocytes and to establish a new cell model for browning research. METHODS To enhance the PPARγ signaling, M3, the transactivation domain of MyoD, was fused to PPARγ. PPARγ and M3-PPARγ-lentiviral vectors were used to convert human myoblasts into adipocytes. Brown adipocyte markers of the reprogrammed adipocytes were assessed by qPCR and protein analyses. White adipocytes differentiated from subcutaneous stromal vascular cells and perithyroid brown fat tissues were used as references. RESULTS In transient transfections, M3-PPARγ had a stronger constitutive activity than PPARγ by reporter assay. Although the transduction of either PPARγ or M3-PPARγ induced adipogenesis in myoblasts, M3-PPARγ drastically induced the brown adipocyte markers of UCP1, CIDEA, and PRDM16 by 1,050, 2.4, and 5.0 fold, respectively and increased mitochondria contents by 4 fold, compared to PPARγ. CONCLUSIONS Super-activation of PPARγ can effectively convert human myoblasts into brown-like adipocytes and a new approach to derive brown-like adipocytes.
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Affiliation(s)
- Yanbei Zhu
- Medical School of Nanjing University, Nanjing, China
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
| | - Rongze Yang
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
| | - John McLenithan
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
| | - Daozhan Yu
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
| | - Hong Wang
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
| | - Yaping Wang
- Medical School of Nanjing University, Nanjing, China
| | - Devinder Singh
- Department of Surgery, University of Maryland School of Medicine at Baltimore
| | - John Olson
- Department of Surgery, University of Maryland School of Medicine at Baltimore
| | - Carole Sztalryd
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
- VA Research Service, Geriatric Research, Education and Clinical Center, Baltimore Veterans Administration Medical Center, Baltimore
| | - Dalong Zhu
- Medical School of Nanjing University, Nanjing, China
- Da-Wei Gong, M.D., Ph.D. Division of Endocrinology, Diabetes and Nutrition University of Maryland School of Medicine, ; Dalong Zhu, M.D. Ph.D. Department of Endocrinology, Medical School of Nanjing University,
| | - Da-Wei Gong
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine at Baltimore
- VA Research Service, Geriatric Research, Education and Clinical Center, Baltimore Veterans Administration Medical Center, Baltimore
- Da-Wei Gong, M.D., Ph.D. Division of Endocrinology, Diabetes and Nutrition University of Maryland School of Medicine, ; Dalong Zhu, M.D. Ph.D. Department of Endocrinology, Medical School of Nanjing University,
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Saini S, Duraisamy AJ, Bayen S, Vats P, Singh SB. Role of BMP7 in appetite regulation, adipogenesis, and energy expenditure. Endocrine 2015; 48:405-9. [PMID: 25178649 DOI: 10.1007/s12020-014-0406-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/23/2014] [Indexed: 01/16/2023]
Abstract
Bone morphogenetic protein 7 (BMP7), also known as osteogenic protein-1 (OP-1) is a member of Transforming growth factor-β (TGF-β) family of proteins. Bone morphogenetic proteins were discovered in 1965 by Marshal Urist, of which BMP7 is of particular interest in this review being a leptin-independent anorexinogen and having role in energy expenditure in the brown adipose tissue, which makes it a potential target for preventing/treating obesity. As it has been established that Obesity displays a state of leptin-resistance, thus a protein-like BMP7 which acts through a leptin-independent pathway could give new therapeutic directions. This review will also discuss the synthesis and action of BMP7, along with its receptors and signal transduction. A brief note about BMP7-mediated brown fat development and energy balance is also discussed.
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Affiliation(s)
- Supriya Saini
- Endocrinology and Metabolism Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054, India
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Lowery JW, Intini G, Gamer L, Lotinun S, Salazar VS, Ote S, Cox K, Baron R, Rosen V. Loss of BMPR2 leads to high bone mass due to increased osteoblast activity. J Cell Sci 2015; 128:1308-15. [PMID: 25663702 DOI: 10.1242/jcs.156737] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Imbalances in the ratio of bone morphogenetic protein (BMP) versus activin and TGFβ signaling are increasingly associated with human diseases yet the mechanisms mediating this relationship remain unclear. The type 2 receptors ACVR2A and ACVR2B bind BMPs and activins but the type 2 receptor BMPR2 only binds BMPs, suggesting that type 2 receptor utilization might play a role in mediating the interaction of these pathways. We tested this hypothesis in the mouse skeleton, where bone mass is reciprocally regulated by BMP signaling and activin and TGFβ signaling. We found that deleting Bmpr2 in mouse skeletal progenitor cells (Bmpr2-cKO mice) selectively impaired activin signaling but had no effect on BMP signaling, resulting in an increased bone formation rate and high bone mass. Additionally, activin sequestration had no effect on bone mass in Bmpr2-cKO mice but increased bone mass in wild-type mice. Our findings suggest a novel model whereby BMPR2 availability alleviates receptor-level competition between BMPs and activins and where utilization of ACVR2A and ACVR2B by BMPs comes at the expense of activins. As BMP and activin pathway modulation are of current therapeutic interest, our findings provide important mechanistic insight into the relationship between these pathways in human health.
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Affiliation(s)
- Jonathan W Lowery
- Department of Biomedical Science, Marian University College of Osteopathic Medicine, Indianapolis, IN 46222, USA Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Giuseppe Intini
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Laura Gamer
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Sutada Lotinun
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Valerie S Salazar
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Satoshi Ote
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Karen Cox
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Roland Baron
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Vicki Rosen
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
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Sidossis L, Kajimura S. Brown and beige fat in humans: thermogenic adipocytes that control energy and glucose homeostasis. J Clin Invest 2015; 125:478-86. [PMID: 25642708 DOI: 10.1172/jci78362] [Citation(s) in RCA: 487] [Impact Index Per Article: 54.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Brown adipose tissue (BAT), a specialized fat that dissipates energy to produce heat, plays an important role in the regulation of energy balance. Two types of thermogenic adipocytes with distinct developmental and anatomical features exist in rodents and humans: classical brown adipocytes and beige (also referred to as brite) adipocytes. While classical brown adipocytes are located mainly in dedicated BAT depots of rodents and infants, beige adipocytes sporadically reside with white adipocytes and emerge in response to certain environmental cues, such as chronic cold exposure, a process often referred to as "browning" of white adipose tissue. Recent studies indicate the existence of beige adipocytes in adult humans, making this cell type an attractive therapeutic target for obesity and obesity-related diseases, including type 2 diabetes. This Review aims to cover recent progress in our understanding of the anatomical, developmental, and functional characteristics of brown and beige adipocytes and discuss emerging questions, with a special emphasis on adult human BAT.
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64
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Sepulveda PV, Bush ED, Baar K. Pharmacology of manipulating lean body mass. Clin Exp Pharmacol Physiol 2015; 42:1-13. [PMID: 25311629 PMCID: PMC4383600 DOI: 10.1111/1440-1681.12320] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 09/29/2014] [Accepted: 09/29/2014] [Indexed: 01/04/2023]
Abstract
Dysfunction and wasting of skeletal muscle as a consequence of illness decreases the length and quality of life. Currently, there are few, if any, effective treatments available to address these conditions. Hence, the existence of this unmet medical need has fuelled large scientific efforts. Fortunately, these efforts have shown many of the underlying mechanisms adversely affecting skeletal muscle health. With increased understanding have come breakthrough disease-specific and broad spectrum interventions, some progressing through clinical development. The present review focuses its attention on the role of the antagonistic process regulating skeletal muscle mass before branching into prospective promising therapeutic targets and interventions. Special attention is given to therapies in development against cancer cachexia and Duchenne muscular dystrophy before closing remarks on design and conceptualization of future therapies are presented to the reader.
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Affiliation(s)
- Patricio V Sepulveda
- Department of Physiology, Monash University, Monash College Wellington Rd, Melbourne Victoria, Australia
| | - Ernest D Bush
- Akashi Therapeutics, Cambridge, MA, University of California Davis, Davis, CA, USA
| | - Keith Baar
- Departments of Neurobiology, Physiology and Behaviour and Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
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65
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Craft CS. MAGP1, the extracellular matrix, and metabolism. Adipocyte 2015; 4:60-4. [PMID: 26167404 DOI: 10.4161/adip.32209] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/23/2014] [Accepted: 07/29/2014] [Indexed: 01/11/2023] Open
Abstract
Adipose tissue and the extracellular matrix were once considered passive players in regulating physiological processes. Now, both entities are acknowledged for their capacity to engage signal transduction pathways, and for their involvement in maintaining normal tissue homeostasis. We recently published a series of studies that identified a novel mechanism whereby an extracellular matrix molecule, MAGP1 (microfibril associated glycoprotein 1), can regulate energy metabolism in adipose tissue. MAGP1 is a component of extracellular microfibrils and plays a supportive role in maintaining thermoregulation by indirectly regulating expression of the thermogenic uncoupling proteins (UCPs). The focus of this commentary is to draw attention to the role of the extracellular matrix in regulating the bioavailability of signaling molecules, like transforming growth factor β (TGFβ), and exemplify that a better understanding of the extracellular matrix's biological properties could unveil a new source of therapeutic targets for metabolic diseases.
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Watanabe Y, Miyagoe-Suzuki Y. Possibility of small-molecule-based pharmacotherapy for sarcopenia. THE JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2015. [DOI: 10.7600/jpfsm.4.73] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yuka Watanabe
- Regenerative Medicine Unit, Drug Discovery Research, Astellas Pharma Inc
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67
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Engineering TGF-β superfamily ligands for clinical applications. Trends Pharmacol Sci 2014; 35:648-57. [PMID: 25458539 DOI: 10.1016/j.tips.2014.10.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/14/2014] [Accepted: 10/14/2014] [Indexed: 12/11/2022]
Abstract
TGF-β superfamily ligands govern normal tissue development and homeostasis, and their dysfunction is a hallmark of many diseases. These ligands are also well defined both structurally and functionally. This review focuses on TGF-β superfamily ligand engineering for therapeutic purposes, in particular for regenerative medicine and musculoskeletal disorders. We describe the key discovery that structure-guided mutation of receptor-binding epitopes, especially swapping of these epitopes between ligands, results in new ligands with unique functional properties that can be harnessed clinically. Given the promising results with prototypical engineered TGF-β superfamily ligands, and the vast number of such molecules that remain to be produced and tested, this strategy is likely to hold great promise for the development of new biologics.
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Daquinag AC, Tseng C, Salameh A, Zhang Y, Amaya-Manzanares F, Dadbin A, Florez F, Xu Y, Tong Q, Kolonin MG. Depletion of white adipocyte progenitors induces beige adipocyte differentiation and suppresses obesity development. Cell Death Differ 2014; 22:351-63. [PMID: 25342467 PMCID: PMC4291494 DOI: 10.1038/cdd.2014.148] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 07/29/2014] [Accepted: 08/06/2014] [Indexed: 12/21/2022] Open
Abstract
Overgrowth of white adipose tissue (WAT) in obesity occurs as a result of adipocyte hypertrophy and hyperplasia. Expansion and renewal of adipocytes relies on proliferation and differentiation of white adipocyte progenitors (WAP); however, the requirement of WAP for obesity development has not been proven. Here, we investigate whether depletion of WAP can be used to prevent WAT expansion. We test this approach by using a hunter-killer peptide designed to induce apoptosis selectively in WAP. We show that targeted WAP cytoablation results in a long-term WAT growth suppression despite increased caloric intake in a mouse diet-induced obesity model. Our data indicate that WAP depletion results in a compensatory population of adipose tissue with beige adipocytes. Consistent with reported thermogenic capacity of beige adipose tissue, WAP-depleted mice display increased energy expenditure. We conclude that targeting of white adipocyte progenitors could be developed as a strategy to sustained modulation of WAT metabolic activity.
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Affiliation(s)
- A C Daquinag
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - C Tseng
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - A Salameh
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Y Zhang
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - F Amaya-Manzanares
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - A Dadbin
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - F Florez
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Y Xu
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Q Tong
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - M G Kolonin
- Center for Metabolic and Degenerative Diseases, The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
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69
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Padhi D, Higano CS, Shore ND, Sieber P, Rasmussen E, Smith MR. Pharmacological inhibition of myostatin and changes in lean body mass and lower extremity muscle size in patients receiving androgen deprivation therapy for prostate cancer. J Clin Endocrinol Metab 2014; 99:E1967-75. [PMID: 24971661 DOI: 10.1210/jc.2014-1271] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Myostatin is a negative regulator of muscle growth. Androgen deprivation (ADT) is associated with muscle loss and increased body fat, and currently available therapies have limited efficacy to treat this complication. The antimyostatin peptibody (AMG 745/Mu-S) markedly attenuated muscle loss and decreased fat accumulation in orchiectomized mice. OBJECTIVE The objective of the study was to evaluate the safety, pharmacokinetics, and muscle efficacy of AMG 745 in men undergoing ADT for nonmetastatic prostate cancer. METHODS This was a randomized, blinded, placebo-controlled, multiple-dose, phase 1 study of AMG 745 given for 28 days. The end point of percentage change from baseline in lean body mass (LBM) as assessed by dual x-ray absorptiometry was prespecified. RESULTS Rates of adverse events (AMG 745 vs placebo) were the following: diarrhea (13% vs 9%), fatigue (13% vs 4%), contusion (10% vs 0%), and injection site bruising (6% vs 4%). Exposure increased linearly from 0.3 mg/kg to 3 mg/kg. AMG 745 significantly increased LBM in the 3 mg/kg vs the placebo groups on day 29 by 2.2% (±0.8% SE, P = 0.008); in exploratory fat mass analysis, a decrease of -2.5% (±1.0% SE, P = 0.021) was observed. Pharmacodynamic changes in muscle and fat were maintained at follow-up, 1 month after day 29. CONCLUSION Four weekly s.c. doses of AMG 745 were well tolerated and were associated with increased LBM and decreased fat in the men receiving ADT for nonmetastatic prostate cancer. RESULTS support further investigation of AMG 745 in clinical settings with muscle loss and atrophy.
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Affiliation(s)
- Desmond Padhi
- Department of Medical Sciences (D.P.) and Biostatistics (E.R.), Amgen Inc (D.P.), Thousand Oaks, California 91320; Department of Medicine (C.S.H.), University of Washington, and Fred Hutchinson Cancer Research Center, Seattle, Washington 98109; Carolina Urologic Research Center, (N.D.S.), Myrtle Beach, South Carolina 29579; Urological Associates of Lancaster (P.S.), Lancaster, Pennsylvania 17604; and Massachusetts General Hospital Cancer Center (M.R.S.), Boston, Massachusetts 02114
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Craft CS, Pietka TA, Schappe T, Coleman T, Combs MD, Klein S, Abumrad NA, Mecham RP. The extracellular matrix protein MAGP1 supports thermogenesis and protects against obesity and diabetes through regulation of TGF-β. Diabetes 2014; 63:1920-32. [PMID: 24458361 PMCID: PMC4030109 DOI: 10.2337/db13-1604] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Microfibril-associated glycoprotein 1 (MAGP1) is a component of extracellular matrix microfibrils. Here we show that MAGP1 expression is significantly altered in obese humans, and inactivation of the MAGP1 gene (Mfap2(-/-)) in mice results in adipocyte hypertrophy and predisposition to metabolic dysfunction. Impaired thermoregulation was evident in Mfap2(-/-) mice prior to changes in adiposity, suggesting a causative role for MAGP1 in the increased adiposity and predisposition to diabetes. By 5 weeks of age, Mfap2(-/-) mice were maladaptive to cold challenge, uncoupling protein-1 expression was attenuated in the brown adipose tissue, and there was reduced browning of the subcutaneous white adipose tissue. Levels of transforming growth factor-β (TGF-β) activity were elevated in Mfap2(-/-) adipose tissue, and the treatment of Mfap2(-/-) mice with a TGF-β-neutralizing antibody improved their body temperature and prevented the increased adiposity phenotype. Together, these findings indicate that the regulation of TGF-β by MAGP1 is protective against the effects of metabolic stress, and its absence predisposes individuals to metabolic dysfunction.
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Affiliation(s)
- Clarissa S Craft
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO
| | - Terri A Pietka
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Timothy Schappe
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Trey Coleman
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, MO
| | - Michelle D Combs
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO
| | - Samuel Klein
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MODepartment of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Nada A Abumrad
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MODepartment of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Robert P Mecham
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO
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MacDonald EM, Andres-Mateos E, Mejias R, Simmers JL, Mi R, Park JS, Ying S, Hoke A, Lee SJ, Cohn RD. Denervation atrophy is independent from Akt and mTOR activation and is not rescued by myostatin inhibition. Dis Model Mech 2014; 7:471-81. [PMID: 24504412 PMCID: PMC3974457 DOI: 10.1242/dmm.014126] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The purpose of our study was to compare two acquired muscle atrophies and the use of myostatin inhibition for their treatment. Myostatin naturally inhibits skeletal muscle growth by binding to ActRIIB, a receptor on the cell surface of myofibers. Because blocking myostatin in an adult wild-type mouse induces profound muscle hypertrophy, we applied a soluble ActRIIB receptor to models of disuse (limb immobilization) and denervation (sciatic nerve resection) atrophy. We found that treatment of immobilized mice with ActRIIB prevented the loss of muscle mass observed in placebo-treated mice. Our results suggest that this protection from disuse atrophy is regulated by serum and glucocorticoid-induced kinase (SGK) rather than by Akt. Denervation atrophy, however, was not protected by ActRIIB treatment, yet resulted in an upregulation of the pro-growth factors Akt, SGK and components of the mTOR pathway. We then treated the denervated mice with the mTOR inhibitor rapamycin and found that, despite a reduction in mTOR activation, there is no alteration of the atrophy phenotype. Additionally, rapamycin prevented the denervation-induced upregulation of the mTORC2 substrates Akt and SGK. Thus, our studies show that denervation atrophy is not only independent from Akt, SGK and mTOR activation but also has a different underlying pathophysiological mechanism than disuse atrophy.
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Affiliation(s)
- Elizabeth M MacDonald
- McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Komolka K, Albrecht E, Wimmers K, Michal JJ, Maak S. Molecular heterogeneities of adipose depots - potential effects on adipose-muscle cross-talk in humans, mice and farm animals. J Genomics 2014; 2:31-44. [PMID: 25057322 PMCID: PMC4105427 DOI: 10.7150/jgen.5260] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Adipose tissue is considered as a major endocrine organ that secretes numerous proteins called adipokines. The heterogeneous nature of adipose tissue in different parts of the body suggests respective heterogeneity of proteomes and secretomes. This review consolidates knowledge from recent studies targeting the diversity of different adipose depots affecting the pattern of secreted adipokines and discusses potential consequences for the cross-talk between adipose and skeletal muscle in humans, rodent models and farm animals. Special attention is paid to muscle-associated fat depots like inter- and intramuscular fat that become focus of attention in the context of the rather new notion of skeletal muscle as a major endocrine organ. Understanding the complexity of communication between adipocytes and skeletal muscle cells will allow developing strategies for improvement of human health and for sustainable production of high quality meat.
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Affiliation(s)
- Katrin Komolka
- 1. Research Unit Muscle Biology and Growth, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
| | - Elke Albrecht
- 1. Research Unit Muscle Biology and Growth, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
| | - Klaus Wimmers
- 2. Research Unit Molecular Biology, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
| | - Jennifer J Michal
- 3. Department of Animal Sciences, Washington State University, Pullman, WA 99164, USA
| | - Steffen Maak
- 1. Research Unit Muscle Biology and Growth, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
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Wu H, Mezghenna K, Marmol P, Guo T, Moliner A, Yang SN, Berggren PO, Ibáñez CF. Differential regulation of mouse pancreatic islet insulin secretion and Smad proteins by activin ligands. Diabetologia 2014; 57:148-56. [PMID: 24132781 DOI: 10.1007/s00125-013-3079-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 09/23/2013] [Indexed: 10/26/2022]
Abstract
AIMS/HYPOTHESIS Glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells is regulated by paracrine factors, the identity and mechanisms of action of which are incompletely understood. Activins are expressed in pancreatic islets and have been implicated in the regulation of GSIS. Activins A and B signal through a common set of intracellular components, but it is unclear whether they display similar or distinct functions in glucose homeostasis. METHODS We examined glucose homeostatic responses in mice lacking activin B and in pancreatic islets derived from these mutants. We compared the ability of activins A and B to regulate downstream signalling, ATP production and GSIS in islets and beta cells. RESULTS Mice lacking activin B displayed elevated serum insulin levels and GSIS. Injection of a soluble activin B antagonist phenocopied these changes in wild-type mice. Isolated pancreatic islets from mutant mice showed enhanced GSIS, which could be rescued by exogenous activin B. Activin B negatively regulated GSIS and ATP production in wild-type islets, while activin A displayed the opposite effects. The downstream mediator Smad3 responded preferentially to activin B in pancreatic islets and beta cells, while Smad2 showed a preference for activin A, indicating distinct signalling effects of the two activins. In line with this, overexpression of Smad3, but not Smad2, decreased GSIS in pancreatic islets. CONCLUSIONS/INTERPRETATION These results reveal a tug-of-war between activin ligands in the regulation of insulin secretion by beta cells, and suggest that manipulation of activin signalling could be a useful strategy for the control of glucose homeostasis in diabetes and metabolic disease.
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Affiliation(s)
- Haiya Wu
- Department of Neuroscience, Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Berzelius vag 35, B3 Box 285, SE-171 77, Stockholm, Sweden
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Kajimura S, Saito M. A new era in brown adipose tissue biology: molecular control of brown fat development and energy homeostasis. Annu Rev Physiol 2013; 76:225-49. [PMID: 24188710 DOI: 10.1146/annurev-physiol-021113-170252] [Citation(s) in RCA: 310] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Brown adipose tissue (BAT) is specialized to dissipate chemical energy in the form of heat as a defense against cold and excessive feeding. Interest in the field of BAT biology has exploded in the past few years because of the therapeutic potential of BAT to counteract obesity and obesity-related diseases, including insulin resistance. Much progress has been made, particularly in the areas of BAT physiology in adult humans, developmental lineages of brown adipose cell fate, and hormonal control of BAT thermogenesis. As we enter into a new era of brown fat biology, the next challenge will be to develop strategies for activating BAT thermogenesis in adult humans to increase whole-body energy expenditure. This article reviews the recent major advances in this field and discusses emerging questions.
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Affiliation(s)
- Shingo Kajimura
- Diabetes Center, Department of Cell and Tissue Biology, University of California, San Francisco, California 94143-0669;
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75
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Brown and beige fat: development, function and therapeutic potential. Nat Med 2013; 19:1252-63. [PMID: 24100998 DOI: 10.1038/nm.3361] [Citation(s) in RCA: 1666] [Impact Index Per Article: 151.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 08/27/2013] [Indexed: 12/13/2022]
Abstract
Adipose tissue, best known for its role in fat storage, can also suppress weight gain and metabolic disease through the action of specialized, heat-producing adipocytes. Brown adipocytes are located in dedicated depots and express constitutively high levels of thermogenic genes, whereas inducible 'brown-like' adipocytes, also known as beige cells, develop in white fat in response to various activators. The activities of brown and beige fat cells reduce metabolic disease, including obesity, in mice and correlate with leanness in humans. Many genes and pathways that regulate brown and beige adipocyte biology have now been identified, providing a variety of promising therapeutic targets for metabolic disease.
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Hulmi JJ, Oliveira BM, Silvennoinen M, Hoogaars WMH, Pasternack A, Kainulainen H, Ritvos O. Exercise restores decreased physical activity levels and increases markers of autophagy and oxidative capacity in myostatin/activin-blocked mdx mice. Am J Physiol Endocrinol Metab 2013; 305:E171-82. [PMID: 23695214 DOI: 10.1152/ajpendo.00065.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The importance of adequate levels of muscle size and function and physical activity is widely recognized. Myostatin/activin blocking increases skeletal muscle mass but may decrease muscle oxidative capacity and can thus be hypothesized to affect voluntary physical activity. Soluble activin receptor IIB (sActRIIB-Fc) was produced to block myostatin/activins. Modestly dystrophic mdx mice were injected with sActRIIB-Fc or PBS with or without voluntary wheel running exercise for 7 wk. Healthy mice served as controls. Running for 7 wk attenuated the sActRIIB-Fc-induced increase in body mass by decreasing fat mass. Running also enhanced/restored the markers of muscle oxidative capacity and autophagy in mdx mice to or above the levels of healthy mice. Voluntary running activity was decreased by sActRIIB-Fc during the first 3-4 wk correlating with increased body mass. Home cage physical activity of mice, quantified from the force plate signal, was decreased by sActRIIB-Fc the whole 7-wk treatment in sedentary mice. To understand what happens during the first weeks after sActRIIB-Fc administration, when mice are less active, healthy mice were injected with sActRIIB-Fc or PBS for 2 wk. During the sActRIIB-Fc-induced rapid 2-wk muscle growth period, oxidative capacity and autophagy were reduced, which may possibly explain the decreased running activity. These results show that increased muscle size and decreased markers of oxidative capacity and autophagy during the first weeks of myostatin/activin blocking are associated with decreased voluntary activity levels. Voluntary exercise in dystrophic mice enhances the markers of oxidative capacity and autophagy to or above the levels of healthy mice.
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Affiliation(s)
- Juha J Hulmi
- Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyväskylä, Finland.
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Arch JRS, Trayhurn P. Detection of thermogenesis in rodents in response to anti-obesity drugs and genetic modification. Front Physiol 2013; 4:64. [PMID: 23580228 PMCID: PMC3619105 DOI: 10.3389/fphys.2013.00064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/16/2013] [Indexed: 11/22/2022] Open
Abstract
Many compounds and genetic manipulations are claimed to confer resistance to obesity in rodents by raising energy expenditure. Examples taken from recent and older literature, demonstrate that such claims are often based on measurements of energy expenditure after body composition has changed, and depend on comparisons of energy expenditure divided by body weight. This is misleading because white adipose tissue has less influence than lean tissue on energy expenditure. Application of this approach to human data would suggest that human obesity is usually due to a low metabolic rate, which is not an accepted view. Increased energy expenditure per animal is a surer way of demonstrating thermogenesis, but even then it is important to know whether this is due to altered body composition (repartitioning), or increased locomotor activity rather than thermogenesis per se. Regression analysis offers other approaches. The thermogenic response to some compounds has a rapid onset and so cannot be due to altered body composition. These compounds usually mimic or activate the sympathetic nervous system. Thermogenesis occurs in, but may not be confined to, brown adipose tissue. It should not be assumed that weight loss in response to these treatments is due to thermogenesis unless there is a sustained increase in 24-h energy expenditure. Thyroid hormones and fibroblast growth factor 21 also raise energy expenditure before they affect body composition. Some treatments and genetic modifications alter the diurnal rhythm of energy expenditure. It is important to establish whether this is due to altered locomotor activity or efficiency of locomotion. There are no good examples of compounds that do not affect short-term energy expenditure but have a delayed effect. How and under what conditions a genetic modification or compound increases energy expenditure influences the decision on whether to seek drugs for the target or take a candidate drug into clinical studies.
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McPherron AC, Guo T, Bond ND, Gavrilova O. Increasing muscle mass to improve metabolism. Adipocyte 2013; 2:92-8. [PMID: 23805405 PMCID: PMC3661116 DOI: 10.4161/adip.22500] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 10/08/2012] [Accepted: 10/09/2012] [Indexed: 11/19/2022] Open
Abstract
Skeletal muscle insulin resistance is a predictor of the development of type 2 diabetes and maintenance of adequate muscle glucose disposal in muscle may help to prevent diabetes. Lipodystrophy is a type of diabetes caused by a reduction of white adipose tissue and the adipokine leptin. Lipidemia, insulin resistance and hyperphagia develop as a consequence. In a recent study, we showed that increasing skeletal muscle mass by inhibiting signaling of myostatin, a transforming growth factor β (TGFβ) family member that negatively regulates muscle growth, prevents the development of diabetes in a mouse model of lipodystrophy. Muscle-specific myostatin inhibition also prevented hyperphagia suggesting muscle may regulate food intake. Here we discuss these results in the context of strategies to increase muscle insulin sensitivity as well as new findings about the effects of myostatin and other TGFβ family members on similar metabolic processes.
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Abstract
One of the most promising areas in the therapeutics for metabolic diseases centers around activation of the pathways of energy expenditure. Brown adipose tissue is a particularly appealing target for increasing energy expenditure, given its amazing capacity to transform chemical energy into heat. In addition to classical brown adipose tissue, the last few years have seen great advances in our understanding of inducible thermogenic adipose tissue, also referred to as beige fat. A deeper understanding of the molecular processes involved in the development and function of these cell types may lead to new therapeutics for obesity, diabetes, and other metabolic diseases.
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80
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Shan T, Liang X, Bi P, Kuang S. Myostatin knockout drives browning of white adipose tissue through activating the AMPK-PGC1α-Fndc5 pathway in muscle. FASEB J 2013; 27:1981-9. [PMID: 23362117 DOI: 10.1096/fj.12-225755] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myostatin (Mstn) is predominantly expressed in skeletal muscles and plays important roles in regulating muscle growth and development, as well as fat deposition. Mstn-knockout (Mstn(-/-)) mice exhibit increased muscle mass due to both hypertrophy and hyperplasia, and leaner body composition due to reduced fat mass. Here, we show that white adipose tissue (WAT) of Mstn(-/-) develops characteristics of brown adipose tissue (BAT) with dramatically increased expression of BAT signature genes, including Ucp1 and Pgc1α, and beige adipocyte markers Tmem26 and CD137. Strikingly, the observed browning phenotype is non-cell autonomous and is instead driven by the newly defined myokine irisin (Fndc5) secreted from Mstn(-/-) skeletal muscle. Within the muscle, Mstn(-/-) leads to increased expression of AMPK and its phosphorylation, which subsequently activates PGC1α and Fndc5. Together, our study defines a paradigm of muscle-fat crosstalk mediated by Fndc5, which is up-regulated and secreted from muscle to induce beige cell markers and the browning of WAT in Mstn(-/-) mice. These results suggest that targeting muscle Mstn and its downstream signaling represents a therapeutic approach to treat obesity and type 2 diabetes.
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Affiliation(s)
- Tizhong Shan
- Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA
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Sharp LZ, Shinoda K, Ohno H, Scheel DW, Tomoda E, Ruiz L, Hu H, Wang L, Pavlova Z, Gilsanz V, Kajimura S. Human BAT possesses molecular signatures that resemble beige/brite cells. PLoS One 2012; 7:e49452. [PMID: 23166672 PMCID: PMC3500293 DOI: 10.1371/journal.pone.0049452] [Citation(s) in RCA: 491] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 10/09/2012] [Indexed: 02/06/2023] Open
Abstract
Brown adipose tissue (BAT) dissipates chemical energy and generates heat to protect animals from cold and obesity. Rodents possess two types of UCP-1 positive brown adipocytes arising from distinct developmental lineages: “classical” brown adipocytes develop during the prenatal stage whereas “beige” or “brite” cells that reside in white adipose tissue (WAT) develop during the postnatal stage in response to chronic cold or PPARγ agonists. Beige cells’ inducible characteristics make them a promising therapeutic target for obesity treatment, however, the relevance of this cell type in humans remains unknown. In the present study, we determined the gene signatures that were unique to classical brown adipocytes and to beige cells induced by a specific PPARγ agonist rosiglitazone in mice. Subsequently we applied the transcriptional data to humans and examined the molecular signatures of human BAT isolated from multiple adipose depots. To our surprise, nearly all the human BAT abundantly expressed beige cell-selective genes, but the expression of classical brown fat-selective genes were nearly undetectable. Interestingly, expression of known brown fat-selective genes such as PRDM16 was strongly correlated with that of the newly identified beige cell-selective genes, but not with that of classical brown fat-selective genes. Furthermore, histological analyses showed that a new beige cell marker, CITED1, was selectively expressed in the UCP1-positive beige cells as well as in human BAT. These data indicate that human BAT may be primary composed of beige/brite cells.
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Affiliation(s)
- Louis Z. Sharp
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Kosaku Shinoda
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Haruya Ohno
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
| | - David W. Scheel
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Emi Tomoda
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Lauren Ruiz
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Houchun Hu
- Department of Radiology, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California, United States of America
| | - Larry Wang
- Department of Pathology, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California, United States of America
| | - Zdena Pavlova
- Department of Pathology, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California, United States of America
| | - Vicente Gilsanz
- Department of Radiology, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California, United States of America
| | - Shingo Kajimura
- UCSF Diabetes Center and Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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Yamada AK, Verlengia R, Bueno Junior CR. Myostatin: genetic variants, therapy and gene doping. BRAZ J PHARM SCI 2012. [DOI: 10.1590/s1984-82502012000300003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Since its discovery, myostatin (MSTN) has been at the forefront of muscle therapy research because intrinsic mutations or inhibition of this protein, by either pharmacological or genetic means, result in muscle hypertrophy and hyperplasia. In addition to muscle growth, MSTN inhibition potentially disturbs connective tissue, leads to strength modulation, facilitates myoblast transplantation, promotes tissue regeneration, induces adipose tissue thermogenesis and increases muscle oxidative phenotype. It is also known that current advances in gene therapy have an impact on sports because of the illicit use of such methods. However, the adverse effects of these methods, their impact on athletic performance in humans and the means of detecting gene doping are as yet unknown. The aim of the present review is to discuss biosynthesis, genetic variants, pharmacological/genetic manipulation, doping and athletic performance in relation to the MSTN pathway. As will be concluded from the manuscript, MSTN emerges as a promising molecule for combating muscle wasting diseases and for triggering wide-ranging discussion in view of its possible use in gene doping.
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Affiliation(s)
- Maximilian Bielohuby
- Endocrine Research Unit, Medizinische Klinik und Poliklinik IV, Ziemssenstrasse 1 80336 Munich Germany.
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