201
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McGee SL, Swinton C, Morrison S, Gaur V, Campbell DE, Jorgensen SB, Kemp BE, Baar K, Steinberg GR, Hargreaves M. Compensatory regulation of HDAC5 in muscle maintains metabolic adaptive responses and metabolism in response to energetic stress. FASEB J 2014; 28:3384-95. [DOI: 10.1096/fj.14-249359] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sean L. McGee
- Metabolic Remodelling Laboratory, Metabolic Research UnitSchool of Medicine, Deakin UniversityWaurn PondsVictoriaAustralia
- Division of Cell Signalling and MetabolismBaker International Diabetes Institute Heart and Diabetes InstituteMelbourneVictoriaAustralia
| | - Courtney Swinton
- Metabolic Remodelling Laboratory, Metabolic Research UnitSchool of Medicine, Deakin UniversityWaurn PondsVictoriaAustralia
| | - Shona Morrison
- Metabolic Remodelling Laboratory, Metabolic Research UnitSchool of Medicine, Deakin UniversityWaurn PondsVictoriaAustralia
| | - Vidhi Gaur
- Metabolic Remodelling Laboratory, Metabolic Research UnitSchool of Medicine, Deakin UniversityWaurn PondsVictoriaAustralia
| | - Duncan E. Campbell
- Metabolic Remodelling Laboratory, Metabolic Research UnitSchool of Medicine, Deakin UniversityWaurn PondsVictoriaAustralia
- Department of PhysiologyThe University of MelbourneParkvilleVictoriaAustralia
| | - Sebastian B. Jorgensen
- St. Vincent's InstituteFitzroyVictoriaAustralia
- Diabetes Research UnitNovo Nordisk A/SMaaloevDenmark
| | | | - Keith Baar
- Department of Neurobiology, Physiology, and BehaviorUniversity of CaliforniaDavisCaliforniaUSA
| | - Gregory R. Steinberg
- St. Vincent's InstituteFitzroyVictoriaAustralia
- Department of MedicineMcMaster UniversityHamiltonOntarioCanada
| | - M. Hargreaves
- Department of PhysiologyThe University of MelbourneParkvilleVictoriaAustralia
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202
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Davila JL, Goff LA, Ricupero CL, Camarillo C, Oni EN, Swerdel MR, Toro-Ramos AJ, Li J, Hart RP. A positive feedback mechanism that regulates expression of miR-9 during neurogenesis. PLoS One 2014; 9:e94348. [PMID: 24714615 PMCID: PMC3979806 DOI: 10.1371/journal.pone.0094348] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 03/13/2014] [Indexed: 12/21/2022] Open
Abstract
MiR-9, a neuron-specific miRNA, is an important regulator of neurogenesis. In this study we identify how miR-9 is regulated during early differentiation from a neural stem-like cell. We utilized two immortalized rat precursor clones, one committed to neurogenesis (L2.2) and another capable of producing both neurons and non-neuronal cells (L2.3), to reproducibly study early neurogenesis. Exogenous miR-9 is capable of increasing neurogenesis from L2.3 cells. Only one of three genomic loci capable of encoding miR-9 was regulated during neurogenesis and the promoter region of this locus contains sufficient functional elements to drive expression of a luciferase reporter in a developmentally regulated pattern. Furthermore, among a large number of potential regulatory sites encoded in this sequence, Mef2 stood out because of its known pro-neuronal role. Of four Mef2 paralogs, we found only Mef2C mRNA was regulated during neurogenesis. Removal of predicted Mef2 binding sites or knockdown of Mef2C expression reduced miR-9-2 promoter activity. Finally, the mRNA encoding the Mef2C binding partner HDAC4 was shown to be targeted by miR-9. Since HDAC4 protein could be co-immunoprecipitated with Mef2C protein or with genomic Mef2 binding sequences, we conclude that miR-9 regulation is mediated, at least in part, by Mef2C binding but that expressed miR-9 has the capacity to reduce inhibitory HDAC4, stabilizing its own expression in a positive feedback mechanism.
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Affiliation(s)
- Jonathan L Davila
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Loyal A Goff
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Christopher L Ricupero
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Cynthia Camarillo
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Eileen N Oni
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Mavis R Swerdel
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Alana J Toro-Ramos
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Jiali Li
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Ronald P Hart
- W.M. Keck Center for Collaborative Neuroscience and the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
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203
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Abstract
Regeneration of adult skeletal muscle following injury occurs through the activation of satellite cells, an injury-sensitive muscle stem cell population that proliferates, differentiates, and fuses with injured myofibers. Members of the myocyte enhancer factor 2 (MEF2) family of transcription factors play essential roles in muscle differentiation during embryogenesis, but their potential contributions to adult muscle regeneration have not been systematically explored. To investigate the potential involvement of MEF2 factors in muscle regeneration, we conditionally deleted the Mef2a, c, and d genes, singly and in combination, within satellite cells in mice, using tamoxifen-inducible Cre recombinase under control of the satellite cell-specific Pax7 promoter. We show that deletion of individual Mef2 genes has no effect on muscle regeneration in response to cardiotoxin injury. However, combined deletion of the Mef2a, c, and d genes results in a blockade to regeneration. Satellite cell-derived myoblasts lacking MEF2A, C, and D proliferate normally in culture, but cannot differentiate. The absence of MEF2A, C, and D in satellite cells is associated with aberrant expression of a broad collection of known and unique protein-coding and long noncoding RNA genes. These findings reveal essential and redundant roles of MEF2A, C, and D in satellite cell differentiation and identify a MEF2-dependent transcriptome associated with skeletal muscle regeneration.
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204
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Unraveling the complexities of SIRT1-mediated mitochondrial regulation in skeletal muscle. Exerc Sport Sci Rev 2014; 41:174-81. [PMID: 23792490 DOI: 10.1097/jes.0b013e3182956803] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Sirtuin 1 (SIRT1) is a purported central regulator of skeletal muscle mitochondrial biogenesis. Herein, we discuss our recent work using conditional mouse models, which highlight the complexities of SIRT1 biology in vivo, and question the role of SIRT1 in regulating mitochondrial function and mitochondrial adaptations to endurance exercise. Furthermore, we discuss the possible contribution of proposed SIRT1 substrates to muscle mitochondrial biogenesis.
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205
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Goyaram V, Kohn TA, Ojuka EO. Suppression of the GLUT4 adaptive response to exercise in fructose-fed rats. Am J Physiol Endocrinol Metab 2014; 306:E275-83. [PMID: 24326422 PMCID: PMC3920014 DOI: 10.1152/ajpendo.00342.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Exercise-induced increase in skeletal muscle GLUT4 expression is associated with hyperacetylation of histone H3 within a 350-bp DNA region surrounding the myocyte enhancer factor 2 (MEF2) element on the Glut4 promoter and increased binding of MEF2A. Previous studies have hypothesized that the increase in MEF2A binding is a result of improved accessibility of this DNA segment. Here, we investigated the impact of fructose consumption on exercise-induced GLUT4 adaptive response and directly measured the accessibility of the above segment to nucleases. Male Wistar rats (n = 30) were fed standard chow or chow + 10% fructose or maltodextrin drinks ad libitum for 13 days. In the last 6 days five animals per group performed 3 × 17-min bouts of intermittent swimming daily and five remained untrained. Triceps muscles were harvested and used to measure 1) GLUT4, pAMPK, and HDAC5 contents by Western blot, 2) accessibility of the DNA segment from intact nuclei using nuclease accessibility assays, 3) acetylation level of histone H3 and bound MEF2A by ChIP assays, and 4) glycogen content. Swim training increased GLUT4 content by ∼66% (P < 0.05) but fructose and maltodextrin feeding suppressed the adaptation. Accessibility of the DNA region to MNase and DNase I was significantly increased by swimming (∼2.75- and 5.75-fold, respectively) but was also suppressed in trained rats that consumed fructose or maltodextrin. Histone H3 acetylation and MEF2A binding paralleled the accessibility pattern. These findings indicate that both fructose and maltodextrin modulate the GLUT4 adaptive response to exercise by mechanisms involving chromatin remodeling at the Glut4 promoter.
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Affiliation(s)
- Veeraj Goyaram
- University of Capetown/Medical Research Center, Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
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206
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An HT, Kim J, Yoo S, Ko J. Small leucine zipper protein (sLZIP) negatively regulates skeletal muscle differentiation via interaction with α-actinin-4. J Biol Chem 2013; 289:4969-79. [PMID: 24375477 DOI: 10.1074/jbc.m113.515395] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The small leucine zipper protein (sLZIP) plays a role in transcriptional regulation in various types of cells. However, the role of sLZIP in myogenesis is unknown. We identified α-actinin-4 (ACTN4) as a sLZIP-binding protein. ACTN4 functions as a transcriptional regulator of myocyte enhancer factor (MEF)2, which plays a critical role in expression of muscle-specific genes during skeletal muscle differentiation. We found that ACTN4 translocates to the nucleus, induces myogenic gene expression, and promotes myotube formation during myogenesis. The myogenic process is controlled by an association between myogenic factors and MEF2 transcription factors. ACTN4 increased expression of muscle-specific proteins via interaction with MEF2. However, sLZIP decreased myogenic gene expression and myotube formation during myogenesis via disruption of the association between ACTN4 and MEF2. ACTN4 increased the promoter activities of myogenic genes, whereas sLZIP abrogated the effect of ACTN4 on transcriptional activation of myogenic genes in myoblasts. The C terminus of sLZIP is required for interaction with the C terminus of ACTN4, based on deletion mutant analysis, and sLZIP plays a role in regulation of MEF2 transactivation via interaction with ACTN4. Our results indicate that sLZIP negatively regulates skeletal muscle differentiation via interaction with ACTN4 and that sLZIP can be used as a therapeutic target molecule for treatment of muscle hypertrophy and associated diseases.
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Affiliation(s)
- Hyoung-Tae An
- From the Division of Life Sciences, Korea University, Seoul 136-701, South Korea
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207
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Bouchard C, Rankinen T, Timmons JA. Genomics and genetics in the biology of adaptation to exercise. Compr Physiol 2013; 1:1603-48. [PMID: 23733655 DOI: 10.1002/cphy.c100059] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This article is devoted to the role of genetic variation and gene-exercise interactions in the biology of adaptation to exercise. There is evidence from genetic epidemiology research that DNA sequence differences contribute to human variation in physical activity level, cardiorespiratory fitness in the untrained state, cardiovascular and metabolic response to acute exercise, and responsiveness to regular exercise. Methodological and technological advances have made it possible to undertake the molecular dissection of the genetic component of complex, multifactorial traits, such as those of interest to exercise biology, in terms of tissue expression profile, genes, and allelic variants. The evidence from animal models and human studies is considered. Data on candidate genes, genome-wide linkage results, genome-wide association findings, expression arrays, and combinations of these approaches are reviewed. Combining transcriptomic and genomic technologies has been shown to be more powerful as evidenced by the development of a recent molecular predictor of the ability to increase VO2max with exercise training. For exercise as a behavior and physiological fitness as a state to be major players in public health policies will require that the role of human individuality and the influence of DNA sequence differences be understood. Likewise, progress in the use of exercise in therapeutic medicine will depend to a large extent on our ability to identify the favorable responders for given physiological properties to a given exercise regimen.
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Affiliation(s)
- Claude Bouchard
- Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
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208
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Fan W, Atkins AR, Yu RT, Downes M, Evans RM. Road to exercise mimetics: targeting nuclear receptors in skeletal muscle. J Mol Endocrinol 2013; 51:T87-T100. [PMID: 24280961 PMCID: PMC3936671 DOI: 10.1530/jme-13-0258] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Skeletal muscle is the largest organ in the human body and is the major site for energy expenditure. It exhibits remarkable plasticity in response to physiological stimuli such as exercise. Physical exercise remodels skeletal muscle and enhances its capability to burn calories, which has been shown to be beneficial for many clinical conditions including the metabolic syndrome and cancer. Nuclear receptors (NRs) comprise a class of transcription factors found only in metazoans that regulate major biological processes such as reproduction, development, and metabolism. Recent studies have demonstrated crucial roles for NRs and their co-regulators in the regulation of skeletal muscle energy metabolism and exercise-induced muscle remodeling. While nothing can fully replace exercise, development of exercise mimetics that enhance or even substitute for the beneficial effects of physical exercise would be of great benefit. The unique property of NRs that allows modulation by endogenous or synthetic ligands makes them bona fide therapeutic targets. In this review, we present an overview of the current understanding of the role of NRs and their co-regulators in skeletal muscle oxidative metabolism and summarize recent progress in the development of exercise mimetics that target NRs and their co-regulators.
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Affiliation(s)
- Weiwei Fan
- Gene Expression Laboratory Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037, USA
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209
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Masui K, Tanaka K, Akhavan D, Babic I, Gini B, Matsutani T, Iwanami A, Liu F, Villa GR, Gu Y, Campos C, Zhu S, Yang H, Yong WH, Cloughesy TF, Mellinghoff IK, Cavenee WK, Shaw RJ, Mischel PS. mTOR complex 2 controls glycolytic metabolism in glioblastoma through FoxO acetylation and upregulation of c-Myc. Cell Metab 2013; 18:726-39. [PMID: 24140020 PMCID: PMC3840163 DOI: 10.1016/j.cmet.2013.09.013] [Citation(s) in RCA: 318] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/25/2013] [Accepted: 09/13/2013] [Indexed: 01/06/2023]
Abstract
Aerobic glycolysis (the Warburg effect) is a core hallmark of cancer, but the molecular mechanisms underlying it remain unclear. Here, we identify an unexpected central role for mTORC2 in cancer metabolic reprogramming where it controls glycolytic metabolism by ultimately regulating the cellular level of c-Myc. We show that mTORC2 promotes inactivating phosphorylation of class IIa histone deacetylases, which leads to the acetylation of FoxO1 and FoxO3, and this in turn releases c-Myc from a suppressive miR-34c-dependent network. These central features of activated mTORC2 signaling, acetylated FoxO, and c-Myc levels are highly intercorrelated in clinical samples and with shorter survival of GBM patients. These results identify a specific, Akt-independent role for mTORC2 in regulating glycolytic metabolism in cancer.
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Affiliation(s)
- Kenta Masui
- Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093, USA
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210
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Cui H, Moore J, Ashimi SS, Mason BL, Drawbridge JN, Han S, Hing B, Matthews A, McAdams CJ, Darbro BW, Pieper AA, Waller DA, Xing C, Lutter M. Eating disorder predisposition is associated with ESRRA and HDAC4 mutations. J Clin Invest 2013; 123:4706-13. [PMID: 24216484 PMCID: PMC3809805 DOI: 10.1172/jci71400] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/08/2013] [Indexed: 12/22/2022] Open
Abstract
Anorexia nervosa and bulimia nervosa are common and severe eating disorders (EDs) of unknown etiology. Although genetic factors have been implicated in the psychopathology of EDs, a clear biological pathway has not been delineated. DNA from two large families affected by EDs was collected, and mutations segregating with illness were identified by whole-genome sequencing following linkage mapping or by whole-exome sequencing. In the first family, analysis of twenty members across three generations identified a rare missense mutation in the estrogen-related receptor α (ESRRA) gene that segregated with illness. In the second family, analysis of eight members across four generations identified a missense mutation in the histone deacetylase 4 (HDAC4) gene that segregated with illness. ESRRA and HDAC4 were determined to interact both in vitro in HeLa cells and in vivo in mouse cortex. Transcriptional analysis revealed that HDAC4 potently represses the expression of known ESRRA-induced target genes. Biochemical analysis of candidate mutations revealed that the identified ESRRA mutation decreased its transcriptional activity, while the HDAC4 mutation increased transcriptional repression of ESRRA. Our findings suggest that mutations that result in decreased ESRRA activity increase the risk of developing EDs.
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Affiliation(s)
- Huxing Cui
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jarrette Moore
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sunbola S. Ashimi
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Brittany L. Mason
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jordan N. Drawbridge
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Shizhong Han
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Benjamin Hing
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Abigail Matthews
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Carrie J. McAdams
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Benjamin W. Darbro
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Andrew A. Pieper
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - David A. Waller
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Chao Xing
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Michael Lutter
- Department of Psychiatry, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Pediatrics and
Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA.
Department of Clinical Science, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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211
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Winbanks CE, Chen JL, Qian H, Liu Y, Bernardo BC, Beyer C, Watt KI, Thomson RE, Connor T, Turner BJ, McMullen JR, Larsson L, McGee SL, Harrison CA, Gregorevic P. The bone morphogenetic protein axis is a positive regulator of skeletal muscle mass. ACTA ACUST UNITED AC 2013; 203:345-57. [PMID: 24145169 PMCID: PMC3812980 DOI: 10.1083/jcb.201211134] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The BMP signaling pathway promotes muscle growth and inhibits muscle wasting via SMAD1/5-dependent signaling. Although the canonical transforming growth factor β signaling pathway represses skeletal muscle growth and promotes muscle wasting, a role in muscle for the parallel bone morphogenetic protein (BMP) signaling pathway has not been defined. We report, for the first time, that the BMP pathway is a positive regulator of muscle mass. Increasing the expression of BMP7 or the activity of BMP receptors in muscles induced hypertrophy that was dependent on Smad1/5-mediated activation of mTOR signaling. In agreement, we observed that BMP signaling is augmented in models of muscle growth. Importantly, stimulation of BMP signaling is essential for conservation of muscle mass after disruption of the neuromuscular junction. Inhibiting the phosphorylation of Smad1/5 exacerbated denervation-induced muscle atrophy via an HDAC4-myogenin–dependent process, whereas increased BMP–Smad1/5 activity protected muscles from denervation-induced wasting. Our studies highlight a novel role for the BMP signaling pathway in promoting muscle growth and inhibiting muscle wasting, which may have significant implications for the development of therapeutics for neuromuscular disorders.
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Affiliation(s)
- Catherine E Winbanks
- Division of Cell Signaling and Metabolism, Baker IDI Heart and Diabetes Institute, Melbourne 3004, Australia
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212
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Abstract
Glucose is an important fuel for contracting muscle, and normal glucose metabolism is vital for health. Glucose enters the muscle cell via facilitated diffusion through the GLUT4 glucose transporter which translocates from intracellular storage depots to the plasma membrane and T-tubules upon muscle contraction. Here we discuss the current understanding of how exercise-induced muscle glucose uptake is regulated. We briefly discuss the role of glucose supply and metabolism and concentrate on GLUT4 translocation and the molecular signaling that sets this in motion during muscle contractions. Contraction-induced molecular signaling is complex and involves a variety of signaling molecules including AMPK, Ca(2+), and NOS in the proximal part of the signaling cascade as well as GTPases, Rab, and SNARE proteins and cytoskeletal components in the distal part. While acute regulation of muscle glucose uptake relies on GLUT4 translocation, glucose uptake also depends on muscle GLUT4 expression which is increased following exercise. AMPK and CaMKII are key signaling kinases that appear to regulate GLUT4 expression via the HDAC4/5-MEF2 axis and MEF2-GEF interactions resulting in nuclear export of HDAC4/5 in turn leading to histone hyperacetylation on the GLUT4 promoter and increased GLUT4 transcription. Exercise training is the most potent stimulus to increase skeletal muscle GLUT4 expression, an effect that may partly contribute to improved insulin action and glucose disposal and enhanced muscle glycogen storage following exercise training in health and disease.
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Affiliation(s)
- Erik A Richter
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
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213
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Bongers KS, Fox DK, Ebert SM, Kunkel SD, Dyle MC, Bullard SA, Dierdorff JM, Adams CM. Skeletal muscle denervation causes skeletal muscle atrophy through a pathway that involves both Gadd45a and HDAC4. Am J Physiol Endocrinol Metab 2013; 305:E907-15. [PMID: 23941879 PMCID: PMC3798708 DOI: 10.1152/ajpendo.00380.2013] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Skeletal muscle denervation causes muscle atrophy via complex molecular mechanisms that are not well understood. To better understand these mechanisms, we investigated how muscle denervation increases growth arrest and DNA damage-inducible 45α (Gadd45a) mRNA in skeletal muscle. Previous studies established that muscle denervation strongly induces Gadd45a mRNA, which increases Gadd45a, a small myonuclear protein that is required for denervation-induced muscle fiber atrophy. However, the mechanism by which denervation increases Gadd45a mRNA remained unknown. Here, we demonstrate that histone deacetylase 4 (HDAC4) mediates induction of Gadd45a mRNA in denervated muscle. Using mouse models, we show that HDAC4 is required for induction of Gadd45a mRNA during muscle denervation. Conversely, forced expression of HDAC4 is sufficient to increase skeletal muscle Gadd45a mRNA in the absence of muscle denervation. Moreover, Gadd45a mediates several downstream effects of HDAC4, including induction of myogenin mRNA, induction of mRNAs encoding the embryonic nicotinic acetylcholine receptor, and, most importantly, skeletal muscle fiber atrophy. Because Gadd45a induction is also a key event in fasting-induced muscle atrophy, we tested whether HDAC4 might also contribute to Gadd45a induction during fasting. Interestingly, however, HDAC4 is not required for fasting-induced Gadd45a expression or muscle atrophy. Furthermore, activating transcription factor 4 (ATF4), which contributes to fasting-induced Gadd45a expression, is not required for denervation-induced Gadd45a expression or muscle atrophy. Collectively, these results identify HDAC4 as an important regulator of Gadd45a in denervation-induced muscle atrophy and elucidate Gadd45a as a convergence point for distinct upstream regulators during muscle denervation and fasting.
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Affiliation(s)
- Kale S Bongers
- Departments of Internal Medicine and Molecular Physiology and Biophysics and Fraternal Order of Eagles Diabetes Research Center, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa; and
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214
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Abstract
The heritability of specific phenotypical traits relevant for physical performance has been extensively investigated and discussed by experts from various research fields. By deciphering the complete human DNA sequence, the human genome project has provided impressive insights into the genomic landscape. The hope that this information would reveal the origin of phenotypical traits relevant for physical performance or disease risks has proven overly optimistic, and it is still premature to refer to a 'post-genomic' era of biological science. Linking genomic regions with functions, phenotypical traits and variation in disease risk is now a major experimental bottleneck. The recent deluge of genome-wide association studies (GWAS) generates extensive lists of sequence variants and genes potentially linked to phenotypical traits, but functional insight is at best sparse. The focus of this review is on the complex mechanisms that modulate gene expression. A large fraction of these mechanisms is integrated into the field of epigenetics, mainly DNA methylation and histone modifications, which lead to persistent effects on the availability of DNA for transcription. With the exceptions of genomic imprinting and very rare cases of epigenetic inheritance, epigenetic modifications are not inherited transgenerationally. Along with their susceptibility to external influences, epigenetic patterns are highly specific to the individual and may represent pivotal control centers predisposing towards higher or lower physical performance capacities. In that context, we specifically review how epigenetics combined with classical genetics could broaden our knowledge of genotype-phenotype interactions. We discuss some of the shortcomings of GWAS and explain how epigenetic influences can mask the outcome of quantitative genetic studies. We consider epigenetic influences, such as genomic imprinting and epigenetic inheritance, as well as the life-long variability of epigenetic modification patterns and their potential impact on phenotype with special emphasis on traits related to physical performance. We suggest that epigenetic effects may also play a considerable role in the determination of athletic potential and these effects will need to be studied using more sophisticated quantitative genetic models. In the future, epigenetic status and its potential influence on athletic performance will have to be considered, explored and validated using well controlled model systems before we can begin to extrapolate new findings to complex and heterogeneous human populations. A combination of the fields of genomics, epigenomics and transcriptomics along with improved bioinformatics tools and precise phenotyping, as well as a precise classification of the test populations is required for future research to better understand the inter-relations of exercise physiology, performance traits and also susceptibility towards diseases. Only this combined input can provide the overall outlook necessary to decode the molecular foundation of physical performance.
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Affiliation(s)
- Tobias Ehlert
- Johannes Gutenberg-Universität Mainz, Department of Sports Medicine, Disease Prevention and Rehabilitation, Mainz, Germany
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215
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Miura S, Kai Y, Tadaishi M, Tokutake Y, Sakamoto K, Bruce CR, Febbraio MA, Kita K, Chohnan S, Ezaki O. Marked phenotypic differences of endurance performance and exercise-induced oxygen consumption between AMPK and LKB1 deficiency in mouse skeletal muscle: changes occurring in the diaphragm. Am J Physiol Endocrinol Metab 2013; 305:E213-29. [PMID: 23695215 DOI: 10.1152/ajpendo.00114.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
LKB1 phosphorylates members of the AMP-activated protein kinase (AMPK) family. LKB1 and AMPK in the skeletal muscle are believed to regulate not only fuel oxidation during exercise but also exercise capacity. LKB1 was also required to prevent diaphragm fatigue, which was shown to affect exercise performance. Using mice expressing dominant negative (DN) mutants of LKB1 and AMPK, specifically in the skeletal muscle but not in the heart, we investigated the roles of LKB1 and AMPK activity in exercise performance and the effects of these kinases on the characteristics of respiratory and locomotive muscles. In the diaphragm and gastrocnemius, both AMPK-DN and LKB1-DN mice showed complete loss of AMPKα2 activity, and LKB1-DN mice showed a reduction in LKB1 activity. Exercise capacity was significantly reduced in LKB1-DN mice, with a marked reduction in oxygen consumption and carbon dioxide production during exercise. The diaphragm from LKB1-DN mice showed an increase in myosin heavy chain IIB and glycolytic enzyme expression. Normal respiratory chain function and CPT I activity were shown in the isolated mitochondria from LKB1-DN locomotive muscle, and the expression of genes related to fiber type, mitochondria function, glucose and lipid metabolism, and capillarization in locomotive muscle was not different between LKB1-DN and AMPK-DN mice. We concluded that LKB1 in the skeletal muscle contributes significantly to exercise capacity and oxygen uptake during exercise. LKB1 mediated the change of fiber-type distribution in the diaphragm independently of AMPK and might be responsible for the phenotypes we observed.
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Affiliation(s)
- Shinji Miura
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
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216
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Wang SCM, Muscat GEO. Nuclear receptors and epigenetic signaling: novel regulators of glycogen metabolism in skeletal muscle. IUBMB Life 2013; 65:657-64. [PMID: 23846999 DOI: 10.1002/iub.1181] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 04/18/2013] [Indexed: 02/04/2023]
Abstract
Glycogen is an energy storage depot for the mammalian species. This review focuses on recent developments that have identified the role of nuclear hormone receptor (NR) signaling and epigenomic control in the regulation of important genes that modulate glycogen metabolism. Specifically, new studies have revealed that the NR4A subgroup (of the NR superfamily) are strikingly sensitive to beta-adrenergic stimulation in skeletal muscle, and transgenic studies in mice have revealed the expression of these NRs affects endurance and glycogen levels in muscle. Furthermore, other studies have demonstrated that one of the NR coregulator class of enzymes that mediate chromatin remodeling, the histone methyltransferases (for example, protein arginine methyltransferase 4) regulates the expression of several genes involved in glycogen metabolism and glycogen storage diseases in skeletal muscle. Importantly, NRs and histone methyltransferases, have the potential to be pharmacologically exploited and may provide novel targets in the quest to treat disorders of glycogen storage.
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Affiliation(s)
- Shu-Ching Mary Wang
- The University of Queensland, Institute for Molecular Bioscience, Obesity Research Centre, Australia
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217
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Poelkens F, Lammers G, Pardoel EM, Tack CJ, Hopman MTE. Upregulation of skeletal muscle inflammatory genes links inflammation with insulin resistance in women with the metabolic syndrome. Exp Physiol 2013; 98:1485-94. [PMID: 23771909 DOI: 10.1113/expphysiol.2013.072710] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The metabolic syndrome, a combination of interrelated metabolic risk factors, is associated with insulin resistance and promotes the development of cardiovascular diseases and type 2 diabetes mellitus. There is a close link between inflammation and metabolic disease, but the responsible mechanisms remain elusive. The aim of this study was to identify differentially expressed genes in insulin-resistant skeletal muscle tissue of women with the metabolic syndrome compared with healthy control women. Women with the metabolic syndrome (n = 19) and healthy control women (n = 20) were extensively phenotyped, insulin sensitivity was measured using a hyperinsulinaemic euglycaemic clamp, and a skeletal muscle biopsy was obtained. Gene expression levels were compared between the two groups by microarrays. The upregulated genes in skeletal muscle of the women with the metabolic syndrome were primarily enriched for inflammatory response-associated genes. The three most significantly upregulated of this group, interleukin 6 receptor (IL6R), histone deacetylase 9 (HDAC9) and CD97 molecule (CD97), were significantly correlated with insulin resistance. Taken together, these findings suggest an important role for a number of inflammatory-related genes in the development of skeletal muscle insulin resistance.
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Affiliation(s)
- Fleur Poelkens
- M. T. E. Hopman: Radboud University Nijmegen Medical Centre, Department of Physiology (392), PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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218
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Singh A, Happel C, Manna SK, Acquaah-Mensah G, Carrerero J, Kumar S, Nasipuri P, Krausz KW, Wakabayashi N, Dewi R, Boros LG, Gonzalez FJ, Gabrielson E, Wong KK, Girnun G, Biswal S. Transcription factor NRF2 regulates miR-1 and miR-206 to drive tumorigenesis. J Clin Invest 2013; 123:2921-34. [PMID: 23921124 DOI: 10.1172/jci66353] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 04/04/2013] [Indexed: 01/04/2023] Open
Abstract
The mechanisms by which deregulated nuclear factor erythroid-2-related factor 2 (NRF2) and kelch-like ECH-associated protein 1 (KEAP1) signaling promote cellular proliferation and tumorigenesis are poorly understood. Using an integrated genomics and ¹³C-based targeted tracer fate association (TTFA) study, we found that NRF2 regulates miR-1 and miR-206 to direct carbon flux toward the pentose phosphate pathway (PPP) and the tricarboxylic acid (TCA) cycle, reprogramming glucose metabolism. Sustained activation of NRF2 signaling in cancer cells attenuated miR-1 and miR-206 expression, leading to enhanced expression of PPP genes. Conversely, overexpression of miR-1 and miR-206 decreased the expression of metabolic genes and dramatically impaired NADPH production, ribose synthesis, and in vivo tumor growth in mice. Loss of NRF2 decreased the expression of the redox-sensitive histone deacetylase, HDAC4, resulting in increased expression of miR-1 and miR-206, and not only inhibiting PPP expression and activity but functioning as a regulatory feedback loop that repressed HDAC4 expression. In primary tumor samples, the expression of miR-1 and miR-206 was inversely correlated with PPP gene expression, and increased expression of NRF2-dependent genes was associated with poor prognosis. Our results demonstrate that microRNA-dependent (miRNA-dependent) regulation of the PPP via NRF2 and HDAC4 represents a novel link between miRNA regulation, glucose metabolism, and ROS homeostasis in cancer cells.
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Affiliation(s)
- Anju Singh
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
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219
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Paracrine effects of IGF-1 overexpression on the functional decline due to skeletal muscle disuse: molecular and functional evaluation in hindlimb unloaded MLC/mIgf-1 transgenic mice. PLoS One 2013; 8:e65167. [PMID: 23755187 PMCID: PMC3670938 DOI: 10.1371/journal.pone.0065167] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 04/23/2013] [Indexed: 12/18/2022] Open
Abstract
Slow-twitch muscles, devoted to postural maintenance, experience atrophy and weakness during muscle disuse due to bed-rest, aging or spaceflight. These conditions impair motion activities and can have survival implications. Human and animal studies demonstrate the anabolic role of IGF-1 on skeletal muscle suggesting its interest as a muscle disuse countermeasure. Thus, we tested the role of IGF-1 overexpression on skeletal muscle alteration due to hindlimb unloading (HU) by using MLC/mIgf-1 transgenic mice expressing IGF-1 under the transcriptional control of MLC promoter, selectively activated in skeletal muscle. HU produced atrophy in soleus muscle, in terms of muscle weight and fiber cross-sectional area (CSA) reduction, and up-regulation of atrophy gene MuRF1. In parallel, the disuse-induced slow-to-fast fiber transition was confirmed by an increase of the fast-type of the Myosin Heavy Chain (MHC), a decrease of PGC-1α expression and an increase of histone deacetylase-5 (HDAC5). Consistently, functional parameters such as the resting chloride conductance (gCl) together with ClC-1 chloride channel expression were increased and the contractile parameters were modified in soleus muscle of HU mice. Surprisingly, IGF-1 overexpression in HU mice was unable to counteract the loss of muscle weight and the decrease of fiber CSA. However, the expression of MuRF1 was recovered, suggesting early effects on muscle atrophy. Although the expression of PGC-1α and MHC were not improved in IGF-1-HU mice, the expression of HDAC5 was recovered. Importantly, the HU-induced increase of gCl was fully contrasted in IGF-1 transgenic mice, as well as the changes in contractile parameters. These results indicate that, even if local expression does not seem to attenuate HU-induced atrophy and slow-to-fast phenotype transition, it exerts early molecular effects on gene expression which can counteract the HU-induced modification of electrical and contractile properties. MuRF1 and HDAC5 can be attractive therapeutic targets for pharmacological countermeasures and then deserve further investigations.
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220
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Sebastian S, Faralli H, Yao Z, Rakopoulos P, Palii C, Cao Y, Singh K, Liu QC, Chu A, Aziz A, Brand M, Tapscott SJ, Dilworth FJ. Tissue-specific splicing of a ubiquitously expressed transcription factor is essential for muscle differentiation. Genes Dev 2013; 27:1247-59. [PMID: 23723416 DOI: 10.1101/gad.215400.113] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alternate splicing contributes extensively to cellular complexity by generating protein isoforms with divergent functions. However, the role of alternate isoforms in development remains poorly understood. Mef2 transcription factors are essential transducers of cell signaling that modulate differentiation of many cell types. Among Mef2 family members, Mef2D is unique, as it undergoes tissue-specific splicing to generate a muscle-specific isoform. Since the ubiquitously expressed (Mef2Dα1) and muscle-specific (Mef2Dα2) isoforms of Mef2D are both expressed in muscle, we examined the relative contribution of each Mef2D isoform to differentiation. Using both in vitro and in vivo models, we demonstrate that Mef2D isoforms act antagonistically to modulate differentiation. While chromatin immunoprecipitation (ChIP) sequencing analysis shows that the Mef2D isoforms bind an overlapping set of genes, only Mef2Dα2 activates late muscle transcription. Mechanistically, the differential ability of Mef2D isoforms to activate transcription depends on their susceptibility to phosphorylation by protein kinase A (PKA). Phosphorylation of Mef2Dα1 by PKA provokes its association with corepressors. Conversely, exon switching allows Mef2Dα2 to escape this inhibitory phosphorylation, permitting recruitment of Ash2L for transactivation of muscle genes. Thus, our results reveal a novel mechanism in which a tissue-specific alternate splicing event has evolved that permits a ubiquitously expressed transcription factor to escape inhibitory signaling for temporal regulation of gene expression.
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Affiliation(s)
- Soji Sebastian
- Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario K1H 8L6, Canada
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221
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Gan Z, Rumsey J, Hazen BC, Lai L, Leone TC, Vega RB, Xie H, Conley KE, Auwerx J, Smith SR, Olson EN, Kralli A, Kelly DP. Nuclear receptor/microRNA circuitry links muscle fiber type to energy metabolism. J Clin Invest 2013; 123:2564-75. [PMID: 23676496 DOI: 10.1172/jci67652] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 03/08/2013] [Indexed: 11/17/2022] Open
Abstract
The mechanisms involved in the coordinate regulation of the metabolic and structural programs controlling muscle fitness and endurance are unknown. Recently, the nuclear receptor PPARβ/δ was shown to activate muscle endurance programs in transgenic mice. In contrast, muscle-specific transgenic overexpression of the related nuclear receptor, PPARα, results in reduced capacity for endurance exercise. We took advantage of the divergent actions of PPARβ/δ and PPARα to explore the downstream regulatory circuitry that orchestrates the programs linking muscle fiber type with energy metabolism. Our results indicate that, in addition to the well-established role in transcriptional control of muscle metabolic genes, PPARβ/δ and PPARα participate in programs that exert opposing actions upon the type I fiber program through a distinct muscle microRNA (miRNA) network, dependent on the actions of another nuclear receptor, estrogen-related receptor γ (ERRγ). Gain-of-function and loss-of-function strategies in mice, together with assessment of muscle biopsies from humans, demonstrated that type I muscle fiber proportion is increased via the stimulatory actions of ERRγ on the expression of miR-499 and miR-208b. This nuclear receptor/miRNA regulatory circuit shows promise for the identification of therapeutic targets aimed at maintaining muscle fitness in a variety of chronic disease states, such as obesity, skeletal myopathies, and heart failure.
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Affiliation(s)
- Zhenji Gan
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute, Orlando, Florida 32827, USA
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222
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Kirchner H, Osler ME, Krook A, Zierath JR. Epigenetic flexibility in metabolic regulation: disease cause and prevention? Trends Cell Biol 2013; 23:203-9. [DOI: 10.1016/j.tcb.2012.11.008] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 11/28/2012] [Accepted: 11/29/2012] [Indexed: 12/21/2022]
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223
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Abstract
New-onset diabetes after transplantation independently increases the risk of cardiovascular disease, infections, and graft loss and decreases patient survival. The required balance between insulin sensitivity/resistance and insulin secretion is necessary to maintain normal glucose metabolism. Calcineurin inhibitors are standard immunosuppression drugs used after transplantation and have been implicated in the development of new-onset diabetes after transplantation partially by pancreatic β-cell apoptosis and resultant decrease in insulin secretion. The ability of muscle to take up glucose is critical to blood glucose homeostasis. Skeletal muscle is quantitatively the most important tissue in the body for insulin-stimulated glucose disposal and is composed of diverse myofibers that vary in their properties between healthy and insulin-resistant muscle. Various signaling pathways are responsible for remodeling of skeletal muscle, and among these is the calcineurin/nuclear factor of activated T-cell pathway. The mechanism of action of the calcineurin inhibitors is to bind in a complex with a binding protein to calcineurin and inhibit its dephosphorylation and activation of nuclear factor of activated T cells. In this review, we will provide a detailed discussion of the hypothesis that inhibition of calcineurin in tissues involved in insulin sensitivity/resistance could be at least partially responsible for the diabetogenicity seen with the use of calcineurin inhibitors.
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Affiliation(s)
- Harini A Chakkera
- Division of Nephrology and Hypertension, Mayo Clinic, Phoenix, AZ 85054, USA.
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224
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Galmozzi A, Mitro N, Ferrari A, Gers E, Gilardi F, Godio C, Cermenati G, Gualerzi A, Donetti E, Rotili D, Valente S, Guerrini U, Caruso D, Mai A, Saez E, De Fabiani E, Crestani M. Inhibition of class I histone deacetylases unveils a mitochondrial signature and enhances oxidative metabolism in skeletal muscle and adipose tissue. Diabetes 2013; 62:732-42. [PMID: 23069623 PMCID: PMC3581211 DOI: 10.2337/db12-0548] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [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
Chromatin modifications are sensitive to environmental and nutritional stimuli. Abnormalities in epigenetic regulation are associated with metabolic disorders such as obesity and diabetes that are often linked with defects in oxidative metabolism. Here, we evaluated the potential of class-specific synthetic inhibitors of histone deacetylases (HDACs), central chromatin-remodeling enzymes, to ameliorate metabolic dysfunction. Cultured myotubes and primary brown adipocytes treated with a class I-specific HDAC inhibitor showed higher expression of Pgc-1α, increased mitochondrial biogenesis, and augmented oxygen consumption. Treatment of obese diabetic mice with a class I- but not a class II-selective HDAC inhibitor enhanced oxidative metabolism in skeletal muscle and adipose tissue and promoted energy expenditure, thus reducing body weight and glucose and insulin levels. These effects can be ascribed to increased Pgc-1α action in skeletal muscle and enhanced PPARγ/PGC-1α signaling in adipose tissue. In vivo ChIP experiments indicated that inhibition of HDAC3 may account for the beneficial effect of the class I-selective HDAC inhibitor. These results suggest that class I HDAC inhibitors may provide a pharmacologic approach to treating type 2 diabetes.
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MESH Headings
- Adipose Tissue/cytology
- Adipose Tissue/drug effects
- Adipose Tissue/metabolism
- Adipose Tissue/ultrastructure
- Animals
- Anti-Obesity Agents/pharmacology
- Anti-Obesity Agents/therapeutic use
- Cell Line
- Cells, Cultured
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Energy Metabolism/drug effects
- Gene Expression Regulation/drug effects
- Histone Deacetylase 1/antagonists & inhibitors
- Histone Deacetylase 1/metabolism
- Histone Deacetylase 2/antagonists & inhibitors
- Histone Deacetylase 2/metabolism
- Histone Deacetylase Inhibitors/pharmacology
- Histone Deacetylase Inhibitors/therapeutic use
- Hypoglycemic Agents/pharmacology
- Hypoglycemic Agents/therapeutic use
- Male
- Mice
- Mice, Mutant Strains
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Mitochondria, Muscle/ultrastructure
- Molecular Targeted Therapy
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/ultrastructure
- Obesity/complications
- Obesity/drug therapy
- Obesity/metabolism
- Obesity/pathology
- Random Allocation
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Affiliation(s)
- Andrea Galmozzi
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
| | - Nico Mitro
- Laboratorio “Giovanni Armenise-Harvard Foundation,” Università degli Studi di Milano, Milan, Italy
| | - Alessandra Ferrari
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
| | - Elise Gers
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
| | - Federica Gilardi
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
| | - Cristina Godio
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
| | - Gaia Cermenati
- Laboratorio “Giovanni Armenise-Harvard Foundation,” Università degli Studi di Milano, Milan, Italy
| | - Alice Gualerzi
- Laboratorio di Immunoistochimica degli Epiteli, Dipartimento di Morfologia Umana e Scienze Biomediche “Città Studi”, Università degli Studi di Milano, Milan, Italy
| | - Elena Donetti
- Laboratorio di Immunoistochimica degli Epiteli, Dipartimento di Morfologia Umana e Scienze Biomediche “Città Studi”, Università degli Studi di Milano, Milan, Italy
| | - Dante Rotili
- Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Rome, Italy
| | - Sergio Valente
- Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Rome, Italy
| | - Uliano Guerrini
- Unit of Magnetic Resonance Imaging, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Donatella Caruso
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
| | - Antonello Mai
- Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Rome, Italy
| | - Enrique Saez
- Department of Chemical Physiology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California
| | - Emma De Fabiani
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
- Corresponding authors: Maurizio Crestani, , and Emma De Fabiani,
| | - Maurizio Crestani
- Laboratorio “Giovanni Galli” di Biochimica e Biologia Molecolare del Metabolismo e Spettrometria di Massa, Università degli Studi di Milano, Milan, Italy
- Corresponding authors: Maurizio Crestani, , and Emma De Fabiani,
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225
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Hohl M, Wagner M, Reil JC, Müller SA, Tauchnitz M, Zimmer AM, Lehmann LH, Thiel G, Böhm M, Backs J, Maack C. HDAC4 controls histone methylation in response to elevated cardiac load. J Clin Invest 2013; 123:1359-70. [PMID: 23434587 DOI: 10.1172/jci61084] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 01/03/2013] [Indexed: 12/28/2022] Open
Abstract
In patients with heart failure, reactivation of a fetal gene program, including atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), is a hallmark for maladaptive remodeling of the LV. The mechanisms that regulate this reactivation are incompletely understood. Histone acetylation and methylation affect the conformation of chromatin, which in turn governs the accessibility of DNA for transcription factors. Using human LV myocardium, we found that, despite nuclear export of histone deacetylase 4 (HDAC4), upregulation of ANP and BNP in failing hearts did not require increased histone acetylation in the promoter regions of these genes. In contrast, di- and trimethylation of lysine 9 of histone 3 (H3K9) and binding of heterochromatin protein 1 (HP1) in the promoter regions of these genes were substantially reduced. In isolated working murine hearts, an acute increase of cardiac preload induced HDAC4 nuclear export, H3K9 demethylation, HP1 dissociation from the promoter region, and activation of the ANP gene. These processes were reversed in hearts with myocyte-specific deletion of Hdac4. We conclude that HDAC4 plays a central role for rapid modifications of histone methylation in response to variations in cardiac load and may represent a target for pharmacological interventions to prevent maladaptive remodeling in patients with heart failure.
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Affiliation(s)
- Mathias Hohl
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, Homburg, Germany
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226
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Barreiro E, Sznajder JI. Epigenetic regulation of muscle phenotype and adaptation: a potential role in COPD muscle dysfunction. J Appl Physiol (1985) 2013; 114:1263-72. [PMID: 23305984 DOI: 10.1152/japplphysiol.01027.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Quadriceps muscle dysfunction occurs in one-third of patients with chronic obstructive pulmonary disease (COPD) in very early stages of their condition, even prior to the development of airway obstruction. Among several factors, deconditioning and muscle mass loss are the most relevant contributing factors leading to this dysfunction. Moreover, epigenetics, defined as the process whereby gene expression is regulated by heritable mechanisms that do not affect DNA sequence, could be involved in the susceptibility to muscle dysfunction, pathogenesis, and progression. Herein, we review the role of epigenetic mechanisms in muscle development and adaptation to environmental factors such as immobilization and exercise, and their implications in the pathophysiology and susceptibility to muscle dysfunction in COPD. The epigenetic modifications identified so far include DNA methylation, histone acetylation and methylation, and non-coding RNAs such as microRNAs (miRNAs). In the present review, we describe the specific contribution of epigenetic mechanisms to the regulation of embryonic myogenesis, muscle structure and metabolism, immobilization, and exercise, and in muscles of COPD patients. Events related to muscle development and regeneration and the response to exercise and immobilization are tightly regulated by epigenetic mechanisms. These environmental factors play a key role in the outcome of muscle mass and function as well as in the susceptibility to muscle dysfunction in COPD. Future research remains to be done to shed light on the specific target pathways of miRNA function and other epigenetic mechanisms in the susceptibility, pathogenesis, and progression of COPD muscle dysfunction.
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Affiliation(s)
- Esther Barreiro
- Respiratory Medicine Department-Lung Cancer Research Group, Institute of Medical Research of Hospital del Mar (IMIMHospital del Mar, Barcelona Biomedical Research Park (PRBB Barcelona, Spain.
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227
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Bloch W, Zopf E, Zimmer P, Baumann FT. Role of physical activity in tumor patients and possible underlying mechanisms. Eur Rev Aging Phys Act 2013. [DOI: 10.1007/s11556-012-0106-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Abstract
A growing knowledge regarding the influence of exercise on adverse physiologic outcomes associated with cancer and its treatment exists. Aside from its effects on psychological behavior, quality of life, and cancer-related fatigue, physical exercise can target physical and cardio-respiratory fitness, insulin regulation and metabolic syndrome, body weight and composition, and immune function in tumor patients. The increasing number of study results for different cancer types, which prove the positive influences of physical activity in cancer patients, changed the contradictory opinions which existed until the end of the last century. Although an increasing number of studies showing the positive effects of physical activity and more specifically of endurance and resistance training in cancer patients have been published, the underlying mechanisms are mostly unknown. Thus, we summarized the current knowledge of the effects of physical activity and specific training in different tumor entities with specific respect to the possible underlying mechanisms. Especially, the association between physical activity and (1) the improvement of fatigue and the role of free radicals in this process, (2) the counterbalance of tumor-induced cachexia, (3) the improvement of the immune system for supportive tumor treatment, and (4) the possible role of epigenetic modulation against tumor and tumor treatment-dependent adverse physiologic outcomes is focused.
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228
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Walkinshaw DR, Weist R, Xiao L, Yan K, Kim GW, Yang XJ. Dephosphorylation at a conserved SP motif governs cAMP sensitivity and nuclear localization of class IIa histone deacetylases. J Biol Chem 2013; 288:5591-605. [PMID: 23297420 DOI: 10.1074/jbc.m112.445668] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Histone deacetylase 4 (HDAC4) and its paralogs, HDAC5, -7, and -9 (all members of class IIa), possess multiple phosphorylation sites crucial for 14-3-3 binding and subsequent nuclear export. cAMP signaling stimulates nuclear import of HDAC4 and HDAC5, but the underlying mechanisms remain to be elucidated. Here we show that cAMP potentiates nuclear localization of HDAC9. Mutation of an SP motif conserved in HDAC4, -5, and -9 prevents cAMP-stimulated nuclear localization. Unexpectedly, this treatment inhibits phosphorylation at the SP motif, indicating an inverse relationship between the phosphorylation event and nuclear import. Consistent with this, leptomycin B-induced nuclear import and adrenocorticotropic hormone (ACTH) treatment result in the dephosphorylation at the motif. Moreover, the modification synergizes with phosphorylation at a nearby site, and similar kinetics was observed for both phosphorylation events during myoblast and adipocyte differentiation. These results thus unravel a previously unrecognized mechanism whereby cAMP promotes dephosphorylation and differentially regulates multisite phosphorylation and the nuclear localization of class IIa HDACs.
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Affiliation(s)
- Donald R Walkinshaw
- Rosalind and Morris Goodman Cancer Research Center, McGill University, Montréal, Québec H3A 1A3, Canada
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229
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Mihaylova MM, Shaw RJ. Metabolic reprogramming by class I and II histone deacetylases. Trends Endocrinol Metab 2013; 24:48-57. [PMID: 23062770 PMCID: PMC3532556 DOI: 10.1016/j.tem.2012.09.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 09/04/2012] [Accepted: 09/06/2012] [Indexed: 12/25/2022]
Abstract
Accumulating evidence suggests that protein acetylation plays a major regulatory role in many facets of transcriptional control of metabolism. The enzymes that catalyze the addition and removal of acetyl moieties are the histone acetyl transferases (HATs) and histone deacetylases (HDACs), respectively. Several recent studies have uncovered novel mechanisms and contexts in which different HDACs play crucial roles in metabolic control. Understanding the role of class I and II HDACs in different metabolic programs during development, as well as in the physiology and pathology of the adult organism, will lead to novel therapeutics for metabolic disease. Here, we review the current understanding of how class I and class II HDACs contribute to metabolic control.
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230
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Snyder CM, Rice AL, Estrella NL, Held A, Kandarian SC, Naya FJ. MEF2A regulates the Gtl2-Dio3 microRNA mega-cluster to modulate WNT signaling in skeletal muscle regeneration. Development 2013; 140:31-42. [PMID: 23154418 PMCID: PMC3513991 DOI: 10.1242/dev.081851] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2012] [Indexed: 12/21/2022]
Abstract
Understanding the molecular mechanisms of skeletal muscle regeneration is crucial to exploiting this pathway for use in tissue repair. Our data demonstrate that the MEF2A transcription factor plays an essential role in skeletal muscle regeneration in adult mice. Injured Mef2a knockout mice display widespread necrosis and impaired myofiber formation. MEF2A controls this process through its direct regulation of the largest known mammalian microRNA (miRNA) cluster, the Gtl2-Dio3 locus. A subset of the Gtl2-Dio3 miRNAs represses secreted Frizzled-related proteins (sFRPs), inhibitors of WNT signaling. Consistent with these data, Gtl2-Dio3-encoded miRNAs are downregulated in regenerating Mef2a knockout muscle, resulting in upregulated sFRP expression and attenuated WNT activity. Furthermore, myogenic differentiation in Mef2a-deficient myoblasts is rescued by overexpression of miR-410 and miR-433, two miRNAs in the Gtl2-Dio3 locus that repress sFRP2, or by treatment with recombinant WNT3A and WNT5A. Thus, miRNA-mediated modulation of WNT signaling by MEF2A is a requisite step for proper muscle regeneration, and represents an attractive pathway for enhancing regeneration of diseased muscle.
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Affiliation(s)
- Christine M. Snyder
- Department of Biology, Program in Cell and Molecular Biology, Boston University, Boston, MA 02215, USA
| | - Amanda L. Rice
- Department of Biology, Program in Cell and Molecular Biology, Boston University, Boston, MA 02215, USA
| | - Nelsa L. Estrella
- Department of Biology, Program in Cell and Molecular Biology, Boston University, Boston, MA 02215, USA
| | - Aaron Held
- Department of Biology, Program in Cell and Molecular Biology, Boston University, Boston, MA 02215, USA
| | | | - Francisco J. Naya
- Department of Biology, Program in Cell and Molecular Biology, Boston University, Boston, MA 02215, USA
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231
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Della Gaspera B, Armand AS, Lecolle S, Charbonnier F, Chanoine C. Mef2d acts upstream of muscle identity genes and couples lateral myogenesis to dermomyotome formation in Xenopus laevis. PLoS One 2012; 7:e52359. [PMID: 23300648 PMCID: PMC3534117 DOI: 10.1371/journal.pone.0052359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 11/15/2012] [Indexed: 11/18/2022] Open
Abstract
Xenopus myotome is formed by a first medial and lateral myogenesis directly arising from the presomitic mesoderm followed by a second myogenic wave emanating from the dermomyotome. Here, by a series of gain and loss of function experiments, we showed that Mef2d, a member of the Mef2 family of MADS-box transcription factors, appeared as an upstream regulator of lateral myogenesis, and as an inducer of dermomyotome formation at the beginning of neurulation. In the lateral presomitic cells, we showed that Mef2d transactivates Myod expression which is necessary for lateral myogenesis. In the most lateral cells of the presomitic mesoderm, we showed that Mef2d and Paraxis (Tcf15), a member of the Twist family of transcription factors, were co-localized and activate directly the expression of Meox2, which acts upstream of Pax3 expression during dermomyotome formation. Cell tracing experiments confirm that the most lateral Meox2 expressing cells of the presomitic mesoderm correspond to the dermomyotome progenitors since they give rise to the most dorsal cells of the somitic mesoderm. Thus, Xenopus Mef2d couples lateral myogenesis to dermomyotome formation before somite segmentation. These results together with our previous works reveal striking similarities between dermomyotome and tendon formation in Xenopus: both develop in association with myogenic cells and both involve a gene transactivation pathway where one member of the Mef2 family, Mef2d or Mef2c, cooperates with a bHLH protein of the Twist family, Paraxis or Scx (Scleraxis) respectively. We propose that these shared characteristics in Xenopus laevis reflect the existence of a vertebrate ancestral mechanism which has coupled the development of the myogenic cells to the formation of associated tissues during somite compartmentalization.
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Affiliation(s)
- Bruno Della Gaspera
- Centre d'Etude de la Sensori-Motricité, UMR 8194 CNRS, Université Paris Descartes, Centre Universitaire des Saints-Pères, Paris, France.
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232
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Yamamoto H, Morino K, Nishio Y, Ugi S, Yoshizaki T, Kashiwagi A, Maegawa H. MicroRNA-494 regulates mitochondrial biogenesis in skeletal muscle through mitochondrial transcription factor A and Forkhead box j3. Am J Physiol Endocrinol Metab 2012; 303:E1419-27. [PMID: 23047984 DOI: 10.1152/ajpendo.00097.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
MicroRNAs (miRNAs) are important posttranscriptional regulators of various biological pathways. In this study, we focused on the role of miRNAs during mitochondrial biogenesis in skeletal muscle. The expression of miR-494 was markedly decreased in murine myoblast C₂C₁₂ cells during myogenic differentiation, accompanied by an increase in mtDNA. Furthermore, the expression of predicted target genes for miR-494, including mitochondrial transcription factor A (mtTFA) and Forkhead box j3 (Foxj3), was posttranscriptionally increased during myogenic differentiation. Knockdown of miR-494 resulted in increased mitochondrial content and upregulation of mtTFA and Foxj3 at the protein level. A 3'-untranslated region reporter assay revealed that miR-494 knockdown directly upregulated the luciferase activity of mtTFA and Foxj3. All of these observations were reversed by overexpression of miR-494. Furthermore, the miR-494 content significantly decreased after endurance exercise in C57BL/6J mice, accompanied by an increase in expression of mtTFA and Foxj3 proteins. These results suggest that miR-494 regulates mitochondrial biogenesis by downregulating mtTFA and Foxj3 during myocyte differentiation and skeletal muscle adaptation to physical exercise.
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Affiliation(s)
- Hirotaka Yamamoto
- Division of Endocrinology and Metabolism, Department of Medicine, Shiga University of Medical Science, Otsu, Japan
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233
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Raichur S, Teh SH, Ohwaki K, Gaur V, Long YC, Hargreaves M, McGee SL, Kusunoki J. Histone deacetylase 5 regulates glucose uptake and insulin action in muscle cells. J Mol Endocrinol 2012; 49:203-11. [PMID: 22991226 DOI: 10.1530/jme-12-0095] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The class IIa histone deacetylases (HDACs) act as transcriptional repressors by altering chromatin structure through histone deacetylation. This family of enzymes regulates muscle development and phenotype, through regulation of muscle-specific genes including myogenin and MyoD (MYOD1). More recently, class IIa HDACs have been implicated in regulation of genes involved in glucose metabolism. However, the effects of HDAC5 on glucose metabolism and insulin action have not been directly assessed. Knockdown of HDAC5 in human primary muscle cells increased glucose uptake and was associated with increased GLUT4 (SLC2A4) expression and promoter activity but was associated with reduced GLUT1 (SLC2A1) expression. There was no change in PGC-1α (PPARGC1A) expression. The effects of HDAC5 knockdown on glucose metabolism were not due to alterations in the initiation of differentiation, as knockdown of HDAC5 after the onset of differentiation also resulted in increased glucose uptake and insulin-stimulated glycogen synthesis. These data show that inhibition of HDAC5 enhances metabolism and insulin action in muscle cells. As these processes in muscle are dysregulated in metabolic disease, HDAC inhibition could be an effective therapeutic strategy to improve muscle metabolism in these diseases. Therefore, we also examined the effects of the pan HDAC inhibitor, Scriptaid, on muscle cell metabolism. In myotubes, Scriptaid increased histone 3 acetylation, GLUT4 expression, glucose uptake and both oxidative and non-oxidative metabolic flux. Together, these data suggest that HDAC5 regulates muscle glucose metabolism and insulin action and that HDAC inhibitors can be used to modulate these parameters in muscle cells.
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Affiliation(s)
- Suryaprakash Raichur
- Lilly Singapore Centre for Drug Discovery, 8A Biomedical Grove #02-05, Immunos 138648, Singapore
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234
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Pérez-Schindler J, Summermatter S, Salatino S, Zorzato F, Beer M, Balwierz PJ, van Nimwegen E, Feige JN, Auwerx J, Handschin C. The corepressor NCoR1 antagonizes PGC-1α and estrogen-related receptor α in the regulation of skeletal muscle function and oxidative metabolism. Mol Cell Biol 2012; 32:4913-24. [PMID: 23028049 PMCID: PMC3510532 DOI: 10.1128/mcb.00877-12] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 09/23/2012] [Indexed: 01/08/2023] Open
Abstract
Skeletal muscle exhibits a high plasticity and accordingly can quickly adapt to different physiological and pathological stimuli by changing its phenotype largely through diverse epigenetic mechanisms. The nuclear receptor corepressor 1 (NCoR1) has the ability to mediate gene repression; however, its role in regulating biological programs in skeletal muscle is still poorly understood. We therefore studied the mechanistic and functional aspects of NCoR1 function in this tissue. NCoR1 muscle-specific knockout mice exhibited a 7.2% higher peak oxygen consumption (VO(2peak)), a 11% reduction in maximal isometric force, and increased ex vivo fatigue resistance during maximal stimulation. Interestingly, global gene expression analysis revealed a high overlap between the effects of NCoR1 deletion and peroxisome proliferator-activated receptor gamma (PPARγ) coactivator 1α (PGC-1α) overexpression on oxidative metabolism in muscle. Importantly, PPARβ/δ and estrogen-related receptor α (ERRα) were identified as common targets of NCoR1 and PGC-1α with opposing effects on the transcriptional activity of these nuclear receptors. In fact, the repressive effect of NCoR1 on oxidative phosphorylation gene expression specifically antagonizes PGC-1α-mediated coactivation of ERRα. We therefore delineated the molecular mechanism by which a transcriptional network controlled by corepressor and coactivator proteins determines the metabolic properties of skeletal muscle, thus representing a potential therapeutic target for metabolic diseases.
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MESH Headings
- Animals
- Male
- Mice
- Mice, Knockout
- Mice, Transgenic
- Models, Biological
- Muscle Contraction/genetics
- Muscle Contraction/physiology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- Nuclear Receptor Co-Repressor 1/deficiency
- Nuclear Receptor Co-Repressor 1/genetics
- Nuclear Receptor Co-Repressor 1/metabolism
- Oxidative Phosphorylation
- Oxygen Consumption
- PPAR delta/metabolism
- PPAR-beta/metabolism
- Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Estrogen/antagonists & inhibitors
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Trans-Activators/antagonists & inhibitors
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription Factors
- ERRalpha Estrogen-Related Receptor
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Affiliation(s)
| | | | | | - Francesco Zorzato
- Departments of Anesthesia and Biomedicine, Basel University Hospital, Basel, Switzerland
- Department of Experimental and Diagnostic Medicine, University of Ferrara, Ferrara, Italy
| | - Markus Beer
- Biozentrum, University of Basel, Basel, Switzerland
| | - Piotr J. Balwierz
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Erik van Nimwegen
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Jérôme N. Feige
- Novartis Institute for Biomedical Research, Basel, Switzerland
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Johan Auwerx
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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235
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Ferrari A, Fiorino E, Giudici M, Gilardi F, Galmozzi A, Mitro N, Cermenati G, Godio C, Caruso D, De Fabiani E, Crestani M. Linking epigenetics to lipid metabolism: focus on histone deacetylases. Mol Membr Biol 2012; 29:257-66. [PMID: 23095054 DOI: 10.3109/09687688.2012.729094] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A number of recent studies revealed that epigenetic modifications play a central role in the regulation of lipid and of other metabolic pathways such as cholesterol homeostasis, bile acid synthesis, glucose and energy metabolism. Epigenetics refers to aspects of genome functions regulated in a DNA sequence-independent fashion. Chromatin structure is controlled by epigenetic mechanisms through DNA methylation and histone modifications. The main modifications are histone acetylation and deacetylation on specific lysine residues operated by two different classes of enzymes: Histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively. The interaction between these enzymes and histones can activate or repress gene transcription: Histone acetylation opens and activates chromatin, while deacetylation of histones and DNA methylation compact chromatin making it transcriptionally silent. The new evidences on the importance of HDACs in the regulation of lipid and other metabolic pathways will open new perspectives in the comprehension of the pathophysiology of metabolic disorders.
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Affiliation(s)
- Alessandra Ferrari
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italia
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236
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Clocchiatti A, Di Giorgio E, Demarchi F, Brancolini C. Beside the MEF2 axis: unconventional functions of HDAC4. Cell Signal 2012; 25:269-76. [PMID: 23063464 DOI: 10.1016/j.cellsig.2012.10.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/07/2012] [Indexed: 12/17/2022]
Abstract
The class IIa deacetylase HDAC4 is unequivocally known as a negative regulator of MEF2-dependent transcription. In the past years several works have allowed us to understand how different signals, mirroring specific environmental circumstances keep in check the repressive action of HDAC4 against MEF2s. At the same time, pieces of evidence have gradually accumulated about HDAC4 activities emancipated from MEF2s. The aim of this review is to discuss about these "unconventional functions" of HDAC4.
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Affiliation(s)
- Andrea Clocchiatti
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence, Università degli Studi di Udine, P.le Kolbe 4-33100 Udine, Italy
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237
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Kim MS, Akhtar MW, Adachi M, Mahgoub M, Bassel-Duby R, Kavalali ET, Olson EN, Monteggia LM. An essential role for histone deacetylase 4 in synaptic plasticity and memory formation. J Neurosci 2012; 32:10879-86. [PMID: 22875922 PMCID: PMC3480333 DOI: 10.1523/jneurosci.2089-12.2012] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 05/03/2012] [Accepted: 05/30/2012] [Indexed: 12/31/2022] Open
Abstract
Histone deacetylases (HDACs), a family of enzymes involved in epigenetic regulation, have been implicated in the control of synaptic plasticity, as well as learning and memory. Previous work has demonstrated administration of pharmacological HDAC inhibitors, primarily those targeted to class I HDACs, enhance learning and memory as well as long-term potentiation. However, a detailed understanding of the role of class II HDACs in these processes remains elusive. Here, we show that selective loss of Hdac4 in brain results in impairments in hippocampal-dependent learning and memory and long-term synaptic plasticity. In contrast, loss of Hdac5 does not impact learning and memory demonstrating unique roles in brain for individual class II HDACs. These findings suggest that HDAC4 is a crucial positive regulator of learning and memory, both behaviorally and at the cellular level, and that inhibition of Hdac4 activity may have unexpected detrimental effects to these processes.
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Affiliation(s)
| | | | | | | | | | - Ege T. Kavalali
- Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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238
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Hong JS, Noh SH, Lee JS, Kim JM, Hong KC, Lee YS. Effects of polymorphisms in the porcine microRNA miR-1 locus on muscle fiber type composition and miR-1 expression. Gene 2012; 506:211-6. [PMID: 22750317 DOI: 10.1016/j.gene.2012.06.050] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/20/2012] [Indexed: 01/16/2023]
Abstract
MicroRNAs (miRNAs) are a group of evolutionarily conserved small noncoding RNAs with regulatory functions. Increasing evidence suggests that polymorphisms in miRNA genes are associated with phenotypic variation by affecting miRNA expression and/or function. Here, we identified two single nucleotide polymorphisms (SNPs) in the porcine miR-1 locus, both of which were linked and located downstream from the stem-loop miRNA precursor sequence within the primary miR-1 region. An association study on muscle fiber characteristics and meat quality traits was performed with a total of 451 pigs representing three pig breeds (Berkshire, n=153; Landrace, n=125; Yorkshire, n=173). The miR-1 SNPs were significantly associated with type I and type IIa muscle fibers in number and area compositions, respectively, but not with meat quality traits. Notably, these polymorphisms were also significantly associated with altered expression of the primary miR-1 transcript, ultimately leading to comparable changes in the levels of both precursor and mature miR-1. Furthermore, altered miR-1 levels were correlated with the variation in muscle fiber composition. Our data suggest that miR-1 may be a candidate gene associated with muscle fiber type composition.
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Affiliation(s)
- Jae-Sang Hong
- College of Life Sciences and Biotechnology, Korea University, Seoul 136‐713, South Korea
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239
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Juszczuk-Kubiak E, Starzyński RR, Sakowski T, Wicińska K, Flisikowski K. Effects of new polymorphisms in the bovine myocyte enhancer factor 2D (MEF2D) gene on the expression rates of the longissimus dorsi muscle. Mol Biol Rep 2012; 39:8387-93. [PMID: 22714905 PMCID: PMC3383949 DOI: 10.1007/s11033-012-1689-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 06/05/2012] [Indexed: 12/27/2022]
Abstract
Myocyte enhancer factor 2D (MEF2D), a product of the MEF2D gene, belongs to the myocyte enhancer factor 2 (MEF2) protein family which is involved in vertebrate skeletal muscle development and differentiation during myogenesis. The aim of the present study was to search for polymorphisms in the bovine MEF2D gene and to analyze their effect on MEF2D mRNA and on protein expression levels in the longissimus dorsi muscle of Polish Holstein–Friesian cattle. Overall, three novel variations, namely, insertion/deletion g.−818_−814AGCCG and g.−211C<A transversion in the promoter region as well as g.7C<T transition in the 5′untranslated region (5′UTR), were identified by DNA sequencing. A total, 375 unrelated bulls belonging to six different cattle breeds were genotyped, and three combined genotypes (Ins-C-C/Ins-C-C, Del-A-T/Del-A-T and Ins-C-C/Del-A-T) were determined. The frequency of the combined genotype Ins-C-C/Ins-C-C and Del-A-T/Del-A-T was varied between the breeds and the average frequency was 0.521 and 0.037, respectively. Expression analysis showed that the MEF2D variants were highly correlated with MEF2D mRNA and protein levels in the longissimus dorsi muscle of Polish Holstein–Friesian bulls carrying the three different combined genotypes. The highest MEF2D mRNA and protein levels were estimated in the muscle of bulls with the Ins-C-C/Ins-C-C homozygous genotype as compared to the Del-A-T/Del-A-T homozygotes (P < 0.01) and Ins-C-C/Del-A-T heterozygotes (P < 0.05). A preliminary association study showed no significant differences in the carcass quality traits between bulls with various MEF2D combined genotypes in the investigated population of Polish Holstein–Friesian cattle.
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Affiliation(s)
- E Juszczuk-Kubiak
- Department of Molecular Cytogenetics, Polish Academy of Sciences Institute of Genetics and Animal Breeding, Jastrzębiec, 05-552 Magdalenka, Poland.
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240
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Weems JC, Griesel BA, Olson AL. Class II histone deacetylases downregulate GLUT4 transcription in response to increased cAMP signaling in cultured adipocytes and fasting mice. Diabetes 2012; 61:1404-14. [PMID: 22403301 PMCID: PMC3357296 DOI: 10.2337/db11-0737] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Insulin-mediated glucose uptake is highly sensitive to the levels of the facilitative glucose transporter protein, GLUT4. Repression of GLUT4 expression is correlated with insulin resistance in adipose tissue. We have shown that differentiation-dependent GLUT4 transcription was under control of class II histone deacetylases (HDACs). We hypothesized that HDACs may regulate gene expression in adipocytes as a result of adrenergic activation. To test this hypothesis, we activated cAMP signaling in 3T3-L1 adipocytes and in mice after an overnight fast. Chromatin immunoprecipitation experiments showed the association of HDAC4/5 with the GLUT4 promoter in vivo and in vitro in response to elevated cAMP. Knockdown of HDACs by small interfering RNA in cultured adipocytes prevented the cAMP-dependent decrease in GLUT4 transcription. HDAC4/5 recruitment to the GLUT4 promoter was dependent on the GLUT4 liver X receptor (LXR) binding site. Treatment of cells with an LXR agonist prevented the cAMP-dependent decrease in GLUT4 transcription. A loss of function mutation in the LXR response element was required for cAMP-dependent downregulation of GLUT4 expression in vitro, in fasted mice, and in mice subjected to diet-induced obesity. This suggests that activation of LXR signaling can prevent loss of GLUT4 expression in diabetes and obesity.
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241
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Kramerova I, Kudryashova E, Ermolova N, Saenz A, Jaka O, López de Munain A, Spencer MJ. Impaired calcium calmodulin kinase signaling and muscle adaptation response in the absence of calpain 3. Hum Mol Genet 2012; 21:3193-204. [PMID: 22505582 DOI: 10.1093/hmg/dds144] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Mutations in the non-lysosomal, cysteine protease calpain 3 (CAPN3) result in the disease limb girdle muscular dystrophy type 2A (LGMD2A). CAPN3 is localized to several subcellular compartments, including triads, where it plays a structural, rather than a proteolytic, role. In the absence of CAPN3, several triad components are reduced, including the major Ca(2+) release channel, ryanodine receptor (RyR). Furthermore, Ca(2+) release upon excitation is impaired in the absence of CAPN3. In the present study, we show that Ca-calmodulin protein kinase II (CaMKII) signaling is compromised in CAPN3 knockout (C3KO) mice. The CaMK pathway has been previously implicated in promoting the slow skeletal muscle phenotype. As expected, the decrease in CaMKII signaling that was observed in the absence of CAPN3 is associated with a reduction in the slow versus fast muscle fiber phenotype. We show that muscles of WT mice subjected to exercise training activate the CaMKII signaling pathway and increase expression of the slow form of myosin; however, muscles of C3KO mice do not exhibit these adaptive changes to exercise. These data strongly suggest that skeletal muscle's adaptive response to functional demand is compromised in the absence of CAPN3. In agreement with our mouse studies, RyR levels were also decreased in biopsies from LGMD2A patients. Moreover, we observed a preferential pathological involvement of slow fibers in LGMD2A biopsies. Thus, impaired CaMKII signaling and, as a result, a weakened muscle adaptation response identify a novel mechanism that may underlie LGMD2A and suggest a pharmacological target that should be explored for therapy.
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Affiliation(s)
- I Kramerova
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Foster WH, Tidball JG, Wang Y. p38γ activity is required for maintenance of slow skeletal muscle size. Muscle Nerve 2012; 45:266-73. [PMID: 22246884 DOI: 10.1002/mus.22289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
INTRODUCTION p38γ kinase is highly enriched in skeletal muscle and is implicated in myotube formation. However, the activation status of p38γ in muscle is unclear. METHODS p38γ activity in slow and fast adult mouse skeletal muscle tissue was examined, as was the impact of p38γ deficiency on muscle development and gene expression. RESULTS p38γ is preferentially activated in slow muscle, but it is inactive in fast muscle types. Furthermore, the loss of p38γ in mice led to decreased muscle mass associated with a smaller myofiber diameter in slow muscle, but there was no impact on fast muscle in either mass or myofiber diameter. Finally, p38γ-deficient muscle showed selective changes in genes related to muscle growth in slow muscle fibers. CONCLUSION This study provides evidence that p38γ is selectively activated in slow skeletal muscle and is involved in the normal growth and development of a subset of skeletal muscle.
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Affiliation(s)
- William H Foster
- Molecular, Cellular, and Integrated Physiology Program, University of California at Los Angeles, Los Angeles, California, USA
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243
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Absence of RIP140 reveals a pathway regulating glut4-dependent glucose uptake in oxidative skeletal muscle through UCP1-mediated activation of AMPK. PLoS One 2012; 7:e32520. [PMID: 22389706 PMCID: PMC3289711 DOI: 10.1371/journal.pone.0032520] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 01/31/2012] [Indexed: 01/08/2023] Open
Abstract
Skeletal muscle constitutes the major site of glucose uptake leading to increased removal of glucose from the circulation in response to insulin. Type 2 diabetes and obesity are often associated with insulin resistance that can be counteracted by exercise or the use of drugs increasing the relative proportion of oxidative fibers. RIP140 is a transcriptional coregulator with a central role in metabolic tissues and we tested the effect of modulating its level of expression on muscle glucose and lipid metabolism in two mice models. Here, we show that although RIP140 protein is expressed at the same level in both oxidative and glycolytic muscles, it inhibits both fatty acid and glucose utilization in a fiber-type dependent manner. In RIP140-null mice, fatty acid utilization increases in the extensor digitorum longus and this is associated with elevated expression of genes implicated in fatty acid binding and transport. In the RIP140-null soleus, depletion of RIP140 leads to increased GLUT4 trafficking and glucose uptake with no change in Akt activity. AMPK phosphorylation/activity is inhibited in the soleus of RIP140 transgenic mice and increased in RIP140-null soleus. This is associated with increased UCP1 expression and mitochondrial uncoupling revealing the existence of a signaling pathway controlling insulin-independent glucose uptake in the soleus of RIP140-null mice. In conclusion, our findings reinforce the participation of RIP140 in the maintenance of energy homeostasis by acting as an inhibitor of energy production and particularly point to RIP140 as a promising therapeutic target in the treatment of insulin resistance.
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244
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Chen HP, Denicola M, Qin X, Zhao Y, Zhang L, Long XL, Zhuang S, Liu PY, Zhao TC. HDAC inhibition promotes cardiogenesis and the survival of embryonic stem cells through proteasome-dependent pathway. J Cell Biochem 2012; 112:3246-55. [PMID: 21751234 DOI: 10.1002/jcb.23251] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Histone deacetylase (HDAC) inhibition plays a crucial role in mediating cardiogenesis and myocardial protection, whereas HDAC degradation has recently attracted attention in mediating the biological function of HDACs. However, it remains unknown whether HDAC inhibition modulates cardiogenesis and embryonic stem cell (ESC) survival through the proteasome pathway. Using the well-established mouse ESC culture, we demonstrated that HDAC inhibitors, both trichostatin A (TSA,50 nmol/L) and sodium butyrate (NaB, 200 µmol/L) that causes the pronounced reduction of HDAC4 activity, decreased cell death and increased viability of ESCs in response to oxidant stress. HDAC inhibition reduced the cleaved caspases 3, 6, 9, PARP, and TUNEL positive ESCs, which were abrogated with MG132 (0.5 µmol/L), a specific proteasome inhibitor. Furthermore, HDAC inhibition stimulates the growth of embryoid bodies (EB), which are associated with a faster spontaneous rhythmic contraction. HDAC inhibition increases the up-regulation of GATA4, MEF2C, Nkx2.5, cardiac actin, and α-SMA mRNA and protein levels that were abrogated by MG132. TSA and NaB resulted in a significant increase in cardiac lineage commitments that were blocked by the proteasome inhibition. Notably, HDAC inhibitors led to noticeable HDAC4 degradation, which was effectively prevented by MG132. Luciferase assay demonstrates an activation of MEF2 cardiac transcriptional factor by HDAC inhibition, which was repressed by MG132, revealing that the degradation of HDAC4 allows for the activation of MEF2. Taken together, our study is the first to demonstrate that HDAC inhibition through proteasome pathway forms a novel signaling to determine the cardiac lineage commitment and elicits the survival pathway.
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Affiliation(s)
- Hong P Chen
- Department of Surgery, Roger William Medical Center, Boston University Medical School, Providence, Rhode Island 02908, USA
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245
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Various jobs of proteolytic enzymes in skeletal muscle during unloading: facts and speculations. J Biomed Biotechnol 2012; 2012:493618. [PMID: 22496611 PMCID: PMC3303694 DOI: 10.1155/2012/493618] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 10/11/2011] [Accepted: 11/03/2011] [Indexed: 12/19/2022] Open
Abstract
Skeletal muscles, namely, postural muscles, as soleus, suffer from atrophy under disuse. Muscle atrophy development caused by unloading differs from that induced by denervation or other stimuli. Disuse atrophy is supposed to be the result of shift of protein synthesis/proteolysis balance towards protein degradation increase. Maintaining of the balance involves many systems of synthesis and proteolysis, whose activation leads to muscle adaptation to disuse rather than muscle degeneration. Here, we review recent data on activity of signaling systems involved in muscle atrophy development under unloading and muscle adaptation to the lack of support.
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246
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Kramer I, Baertschi S, Halleux C, Keller H, Kneissel M. Mef2c deletion in osteocytes results in increased bone mass. J Bone Miner Res 2012; 27:360-73. [PMID: 22161640 DOI: 10.1002/jbmr.1492] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Myocyte enhancer factors 2 (MEF2) are required for expression of the osteocyte bone formation inhibitor Sost in vitro, implying these transcription factors in bone biology. Here, we analyzed the in vivo function of Mef2c in osteocytes in male and female mice during skeletal growth and aging. Dmp1-Cre-induced Mef2c deficiency led to progressive decreases in Sost expression by 40% and 70% in femoral cortical bone at 3.5 months and 5 to 6 months of age. From 2 to 3 months onward, bone mass was increased in the appendicular and axial skeleton of Mef2c mutant relative to control mice. Cortical thickness and long bone and vertebral trabecular density were elevated. To assess whether the increased bone mass was related to the decreased Sost expression, we characterized 4-month-old heterozygous Sost-deficient mice. Sost heterozygotes displayed similar increases in long bone mass and density as Mef2c mutants, but the relative increases in axial skeletal parameters were mostly smaller. At the cellular level, bone formation parameters were normal in 3.5-month-old Mef2c mutant mice, whereas bone resorption parameters were significantly decreased. Correspondingly, cortical expression of the anti-osteoclastogenic factor and Wnt/β-catenin target gene osteoprotegerin (OPG) was increased by 70% in Mef2c mutant males. Furthermore, cortical expression of the Wnt signaling modulators Sfrp2 and Sfrp3 was strongly deregulated in both sexes. In contrast, heterozygous Sost deficient males displayed mildly increased osteoblastic mineral apposition rate, but osteoclast surface and cortical expression of osteoclastogenic regulators including OPG were normal and Sfrp2 and Sfrp3 were not significantly changed. Together, our data demonstrate that Mef2c regulates cortical Sfrp2 and Sfrp3 expression and is required to maintain normal Sost expression in vivo. Yet, the increased bone mass phenotype of Mef2c mutants is not directly related to the reduced Sost expression. We identified a novel function for Mef2c in control of adult bone mass by regulation of osteoclastic bone resorption.
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Affiliation(s)
- Ina Kramer
- Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Novartis Pharma, Basel, Switzerland
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247
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Abstract
Skeletal muscle responds to exercise by activation of signalling pathways that co-ordinate gene expression to sustain muscle performance. MEF2 (myocyte enhancer factor 2)-dependent transcriptional activation of MHC (myosin heavy chain) genes promotes the transformation from fast-twitch into slow-twitch fibres, with MEF2 activity being tightly regulated by interaction with class IIa HDACs (histone deacetylases). PKD (protein kinase D) is known to directly phosphorylate skeletal muscle class IIa HDACs, mediating their nuclear export and thus derepression of MEF2. In the present study, we report the generation of transgenic mice with inducible conditional expression of a dominant-negative PKD1kd (kinase-dead PKD1) protein in skeletal muscle to assess the role of PKD in muscle function. In control mice, long-term voluntary running experiments resulted in a switch from type IIb+IId/x to type IIa plantaris muscle fibres as measured by indirect immunofluorescence of MHCs isoforms. In mice expressing PKD1kd, this fibre type switch was significantly impaired. These mice exhibited altered muscle fibre composition and decreased running performance compared with control mice. Our findings thus indicate that PKD activity is essential for exercise-induced MEF2-dependent skeletal muscle remodelling in vivo.
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248
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Clocchiatti A, Florean C, Brancolini C. Class IIa HDACs: from important roles in differentiation to possible implications in tumourigenesis. J Cell Mol Med 2012; 15:1833-46. [PMID: 21435179 PMCID: PMC3918040 DOI: 10.1111/j.1582-4934.2011.01321.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Histone deacetylases (HDACs) are important regulators of gene expression. Specific structural features and distinct regulative mechanisms rationalize the separation of the 18 different human HDACs into four classes. The class II comprises a heterogeneous group of nuclear and cytosolic HDACs involved in the regulation of several cellular functions, not just limited to transcriptional repression. In particular, HDAC4, 5, 7 and 9 belong to the subclass IIa and share many transcriptional partners, including members of the MEF2 family. Genetic studies in mice have disclosed the fundamental contribution of class IIa HDACs to specific developmental/differentiation pathways. In this review, we discuss about the recent literature, which hints a role of class IIa HDACs in the development, growth and aggressiveness of cancer cells.
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Affiliation(s)
- Andrea Clocchiatti
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence Università degli Studi di Udine, Udine, Italy
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249
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Minetti GC, Feige JN, Rosenstiel A, Bombard F, Meier V, Werner A, Bassilana F, Sailer AW, Kahle P, Lambert C, Glass DJ, Fornaro M. G i2 Signaling Promotes Skeletal Muscle Hypertrophy, Myoblast Differentiation, and Muscle Regeneration. Sci Signal 2011; 4:ra80. [DOI: 10.1126/scisignal.2002038] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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250
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Richard AF, Demignon J, Sakakibara I, Pujol J, Favier M, Strochlic L, Le Grand F, Sgarioto N, Guernec A, Schmitt A, Cagnard N, Huang R, Legay C, Guillet-Deniau I, Maire P. Genesis of muscle fiber-type diversity during mouse embryogenesis relies on Six1 and Six4 gene expression. Dev Biol 2011; 359:303-20. [DOI: 10.1016/j.ydbio.2011.08.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 07/22/2011] [Accepted: 08/15/2011] [Indexed: 01/28/2023]
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