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Saini A, Sharples AP, Al-Shanti N, Stewart CE. Omega-3 fatty acid EPA improves regenerative capacity of mouse skeletal muscle cells exposed to saturated fat and inflammation. Biogerontology 2016; 18:109-129. [PMID: 27864687 PMCID: PMC5288450 DOI: 10.1007/s10522-016-9667-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/05/2016] [Indexed: 12/17/2022]
Abstract
Sarcopenic obesity is characterised by high fat mass, low muscle mass and an elevated inflammatory environmental milieu. We therefore investigated the effects of elevated inflammatory cytokine TNF-α (aging/obesity) and saturated fatty acid, palmitate (obesity) on skeletal muscle cells in the presence/absence of EPA, a-3 polyunsaturated fatty acid with proposed anti-inflammatory, anti-obesity activities. In the present study we show that palmitate was lipotoxic, inducing high levels of cell death and blocking myotube formation. Cell death under these conditions was associated with increased caspase activity, suppression of differentiation, reductions in both creatine kinase activity and gene expression of myogenic factors; IGF-II, IGFBP-5, MyoD and myogenin. However, inhibition of caspase activity via administration of Z-VDVAD-FMK (caspase-2), Z-DEVD-FMK (caspase-3) and ZIETD-KMK (caspase 8) was without effect on cell death. By contrast, lipotoxicity associated with elevated palmitate was reduced with the MEK inhibitor PD98059, indicating palmitate induced cell death was MAPK mediated. These lipotoxic conditions were further exacerbated in the presence of inflammation via TNF-α co-administration. Addition of EPA under cytotoxic stress (TNF-α) was shown to partially rescue differentiation with enhanced myotube formation being associated with increased MyoD, myogenin, IGF-II and IGFBP-5 expression. EPA had little impact on the cell death phenotype observed in lipotoxic conditions but did show benefit in restoring differentiation under lipotoxic plus cytotoxic conditions. Under these conditions Id3 (inhibitor of differentiation) gene expression was inversely linked with survival rates, potentially indicating a novel role of EPA and Id3 in the regulation of apoptosis in lipotoxic/cytotoxic conditions. Additionally, signalling studies indicated the combination of lipo- and cyto-toxic effects on the muscle cells acted through ceramide, JNK and MAPK pathways and blocking these pathways using PD98059 (MEK inhibitor) and Fumonisin B1 (ceramide inhibitor) significantly reduced levels of cell death. These findings highlight novel pathways associated with in vitro models of lipotoxicity (palmitate-mediated) and cytotoxicity (inflammatory cytokine mediated) in the potential targeting of molecular modulators of sarcopenic obesity.
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Affiliation(s)
- Amarjit Saini
- Department of Laboratory Medicine, Clinical Physiology, Karolinska Institutet, and Unit of Clinical Physiology, Karolinska University Hospital, 141 86, Stockholm, Sweden
| | - Adam P Sharples
- Stem Cells, Ageing and Molecular Physiology (SCAMP) Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport & Exercise Sciences, School of Sport and Exercise Sciences, Liverpool John Moores University, Life Science Building, Byrom Street Campus, Liverpool, L3 3AF, UK.
| | - Nasser Al-Shanti
- Neuromuscular and Skeletal Ageing Research Group, Healthcare Science Research Institute, Manchester Metropolitan University, Oxford Road, Manchester, M1 5GD, UK
| | - Claire E Stewart
- Stem Cells, Ageing and Molecular Physiology (SCAMP) Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport & Exercise Sciences, School of Sport and Exercise Sciences, Liverpool John Moores University, Life Science Building, Byrom Street Campus, Liverpool, L3 3AF, UK
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2
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Girven M, Dugdale HF, Owens DJ, Hughes DC, Stewart CE, Sharples AP. l-glutamine Improves Skeletal Muscle Cell Differentiation and Prevents Myotube Atrophy After Cytokine (TNF-α) Stress Via Reduced p38 MAPK Signal Transduction. J Cell Physiol 2016; 231:2720-32. [PMID: 26991744 DOI: 10.1002/jcp.25380] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/15/2016] [Indexed: 02/06/2023]
Abstract
Tumour Necrosis Factor-Alpha (TNF-α) is chronically elevated in conditions where skeletal muscle loss occurs. As l-glutamine can dampen the effects of inflamed environments, we investigated the role of l-glutamine in both differentiating C2C12 myoblasts and existing myotubes in the absence/presence of TNF-α (20 ng · ml(-1) ) ± l-glutamine (20 mM). TNF-α reduced the proportion of cells in G1 phase, as well as biochemical (CK activity) and morphological differentiation (myotube number), with corresponding reductions in transcript expression of: Myogenin, Igf-I, and Igfbp5. Furthermore, when administered to mature myotubes, TNF-α induced myotube loss and atrophy underpinned by reductions in Myogenin, Igf-I, Igfbp2, and glutamine synthetase and parallel increases in Fox03, Cfos, p53, and Bid gene expression. Investigation of signaling activity suggested that Akt and ERK1/2 were unchanged, JNK increased (non-significantly) whereas P38 MAPK substantially and significantly increased in both myoblasts and myotubes in the presence of TNF-α. Importantly, 20 mM l-glutamine reduced p38 MAPK activity in TNF-α conditions back to control levels, with a corresponding rescue of myoblast differentiation and a reversal of atrophy in myotubes. l-glutamine resulted in upregulation of genes associated with growth and survival including; Myogenin, Igf-Ir, Myhc2 & 7, Tnfsfr1b, Adra1d, and restored atrophic gene expression of Fox03 back to baseline in TNF-α conditions. In conclusion, l-glutamine supplementation rescued suppressed muscle cell differentiation and prevented myotube atrophy in an inflamed environment via regulation of p38 MAPK. l-glutamine administration could represent an important therapeutic strategy for reducing muscle loss in catabolic diseases and inflamed ageing. J. Cell. Physiol. 9999: 231: 2720-2732, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Matthew Girven
- Stem Cells, Ageing and Molecular Physiology Research Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom
| | - Hannah F Dugdale
- Stem Cells, Ageing and Molecular Physiology Research Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom
| | - Daniel J Owens
- Stem Cells, Ageing and Molecular Physiology Research Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom.,Sorbonne Universités, UPMC University of Paris 06, INSERM UMRS974, CNRS FRE3617, Centre de Recherche en Myologie (CRM), GH Pitié Salpêtrière, Paris 13, France
| | - David C Hughes
- Stem Cells, Ageing and Molecular Physiology Research Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom.,Department of Neurobiology, Physiology and Behavior, University of California Davis, Davis, California
| | - Claire E Stewart
- Stem Cells, Ageing and Molecular Physiology Research Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom
| | - Adam P Sharples
- Stem Cells, Ageing and Molecular Physiology Research Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom
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Owens DJ, Sharples AP, Polydorou I, Alwan N, Donovan T, Tang J, Fraser WD, Cooper RG, Morton JP, Stewart C, Close GL. A systems-based investigation into vitamin D and skeletal muscle repair, regeneration, and hypertrophy. Am J Physiol Endocrinol Metab 2015; 309:E1019-31. [PMID: 26506852 DOI: 10.1152/ajpendo.00375.2015] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 10/19/2015] [Indexed: 01/08/2023]
Abstract
Skeletal muscle is a direct target for vitamin D. Observational studies suggest that low 25[OH]D correlates with functional recovery of skeletal muscle following eccentric contractions in humans and crush injury in rats. However, a definitive association is yet to be established. To address this gap in knowledge in relation to damage repair, a randomised, placebo-controlled trial was performed in 20 males with insufficient concentrations of serum 25(OH)D (45 ± 25 nmol/l). Prior to and following 6 wk of supplemental vitamin D3 (4,000 IU/day) or placebo (50 mg of cellulose), participants performed 20 × 10 damaging eccentric contractions of the knee extensors, with peak torque measured over the following 7 days of recovery. Parallel experimentation using isolated human skeletal muscle-derived myoblast cells from biopsies of 14 males with low serum 25(OH)D (37 ± 11 nmol/l) were subjected to mechanical wound injury, which enabled corresponding in vitro studies of muscle repair, regeneration, and hypertrophy in the presence and absence of 10 or 100 nmol 1α,25(OH)2D3. Supplemental vitamin D3 increased serum 25(OH)D and improved recovery of peak torque at 48 h and 7 days postexercise. In vitro, 10 nmol 1α,25(OH)2D3 improved muscle cell migration dynamics and resulted in improved myotube fusion/differentiation at the biochemical, morphological, and molecular level together with increased myotube hypertrophy at 7 and 10 days postdamage. Together, these preliminary data are the first to characterize a role for vitamin D in human skeletal muscle regeneration and suggest that maintaining serum 25(OH)D may be beneficial for enhancing reparative processes and potentially for facilitating subsequent hypertrophy.
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Affiliation(s)
- Daniel J Owens
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Adam P Sharples
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Ioanna Polydorou
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Nura Alwan
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Timothy Donovan
- Department of Sport and Exercise Sciences, Glyndwr University, Plas Coch Campus, Wrexham, United Kingdom
| | - Jonathan Tang
- Faculty of Medicine and Health Science, Norwich Medical School, University of East Anglia, Norwich, United Kingdom; and
| | - William D Fraser
- Faculty of Medicine and Health Science, Norwich Medical School, University of East Anglia, Norwich, United Kingdom; and
| | - Robert G Cooper
- Medical Research Council-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, University of Liverpool, Liverpool, United Kingdom
| | - James P Morton
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Claire Stewart
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Graeme L Close
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom;
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Sharples AP, Polydorou I, Hughes DC, Owens DJ, Hughes TM, Stewart CE. Skeletal muscle cells possess a 'memory' of acute early life TNF-α exposure: role of epigenetic adaptation. Biogerontology 2015; 17:603-17. [PMID: 26349924 DOI: 10.1007/s10522-015-9604-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/27/2015] [Indexed: 12/20/2022]
Abstract
Sufficient quantity and quality of skeletal muscle is required to maintain lifespan and healthspan into older age. The concept of skeletal muscle programming/memory has been suggested to contribute to accelerated muscle decline in the elderly in association with early life stress such as fetal malnutrition. Further, muscle cells in vitro appear to remember the in vivo environments from which they are derived (e.g. cancer, obesity, type II diabetes, physical inactivity and nutrient restriction). Tumour-necrosis factor alpha (TNF-α) is a pleiotropic cytokine that is chronically elevated in sarcopenia and cancer cachexia. Higher TNF-α levels are strongly correlated with muscle loss, reduced strength and therefore morbidity and earlier mortality. We have extensively shown that TNF-α impairs regenerative capacity in mouse and human muscle derived stem cells [Meadows et al. (J Cell Physiol 183(3):330-337, 2000); Foulstone et al. (J Cell Physiol 189(2):207-215, 2001); Foulstone et al. (Exp Cell Res 294(1):223-235, 2004); Stewart et al. (J Cell Physiol 198(2):237-247, 2004); Al-Shanti et al. (Growth factors (Chur, Switzerland) 26(2):61-73, 2008); Saini et al. (Growth factors (Chur, Switzerland) 26(5):239-253, 2008); Sharples et al. (J Cell Physiol 225(1):240-250, 2010)]. We have also recently established an epigenetically mediated mechanism (SIRT1-histone deacetylase) regulating survival of myoblasts in the presence of TNF-α [Saini et al. (Exp Physiol 97(3):400-418, 2012)]. We therefore wished to extend this work in relation to muscle memory of catabolic stimuli and the potential underlying epigenetic modulation of muscle loss. To enable this aim; C2C12 myoblasts were cultured in the absence or presence of early TNF-α (early proliferative lifespan) followed by 30 population doublings in the absence of TNF-α, prior to the induction of differentiation in low serum media (LSM) in the absence or presence of late TNF-α (late proliferative lifespan). The cells that received an early plus late lifespan dose of TNF-α exhibited reduced morphological (myotube number) and biochemical (creatine kinase activity) differentiation vs. control cells that underwent the same number of proliferative divisions but only a later life encounter with TNF-α. This suggested that muscle cells had a morphological memory of the acute early lifespan TNF-α encounter. Importantly, methylation of myoD CpG islands were increased in the early TNF-α cells, 30 population doublings later, suggesting that even after an acute encounter with TNF-α, the cells have the capability of retaining elevated methylation for at least 30 cellular divisions. Despite these fascinating findings, there were no further increases in myoD methylation or changes in its gene expression when these cells were exposed to a later TNF-α dose suggesting that this was not directly responsible for the decline in differentiation observed. In conclusion, data suggest that elevated myoD methylation is retained throughout muscle cells proliferative lifespan as result of early life TNF-α treatment and has implications for the epigenetic control of muscle loss.
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Affiliation(s)
- Adam P Sharples
- Stem Cells, Ageing and Molecular Physiology Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
| | - Ioanna Polydorou
- Department of Neuropediatrics and NeuroCure Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.,UFR des Sciences de la Santé, Université de Versailles Saint-Quentin-en-Yvelines, Montigny-Le-Bretonneux, France
| | - David C Hughes
- Stem Cells, Ageing and Molecular Physiology Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.,Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA, USA
| | - Daniel J Owens
- Stem Cells, Ageing and Molecular Physiology Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Thomas M Hughes
- Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan, Ghent, Belgium.,Instituto de Física y Astronomía, Universidad de Valparaíso, Valparaiso, Chile
| | - Claire E Stewart
- Stem Cells, Ageing and Molecular Physiology Unit, Exercise Metabolism and Adaptation Research Group, Research Institute for Sport and Exercise Sciences (RISES), School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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Meyer SU, Sass S, Mueller NS, Krebs S, Bauersachs S, Kaiser S, Blum H, Thirion C, Krause S, Theis FJ, Pfaffl MW. Integrative Analysis of MicroRNA and mRNA Data Reveals an Orchestrated Function of MicroRNAs in Skeletal Myocyte Differentiation in Response to TNF-α or IGF1. PLoS One 2015; 10:e0135284. [PMID: 26270642 PMCID: PMC4536022 DOI: 10.1371/journal.pone.0135284] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 07/20/2015] [Indexed: 12/23/2022] Open
Abstract
Introduction Skeletal muscle cell differentiation is impaired by elevated levels of the inflammatory cytokine tumor necrosis factor-α (TNF-α) with pathological significance in chronic diseases or inherited muscle disorders. Insulin like growth factor-1 (IGF1) positively regulates muscle cell differentiation. Both, TNF-α and IGF1 affect gene and microRNA (miRNA) expression in this process. However, computational prediction of miRNA-mRNA relations is challenged by false positives and targets which might be irrelevant in the respective cellular transcriptome context. Thus, this study is focused on functional information about miRNA affected target transcripts by integrating miRNA and mRNA expression profiling data. Methodology/Principal Findings Murine skeletal myocytes PMI28 were differentiated for 24 hours with concomitant TNF-α or IGF1 treatment. Both, mRNA and miRNA expression profiling was performed. The data-driven integration of target prediction and paired mRNA/miRNA expression profiling data revealed that i) the quantity of predicted miRNA-mRNA relations was reduced, ii) miRNA targets with a function in cell cycle and axon guidance were enriched, iii) differential regulation of anti-differentiation miR-155-5p and miR-29b-3p as well as pro-differentiation miR-335-3p, miR-335-5p, miR-322-3p, and miR-322-5p seemed to be of primary importance during skeletal myoblast differentiation compared to the other miRNAs, iv) the abundance of targets and affected biological processes was miRNA specific, and v) subsets of miRNAs may collectively regulate gene expression. Conclusions Joint analysis of mRNA and miRNA profiling data increased the process-specificity and quality of predicted relations by statistically selecting miRNA-target interactions. Moreover, this study revealed miRNA-specific predominant biological implications in skeletal muscle cell differentiation and in response to TNF-α or IGF1 treatment. Furthermore, myoblast differentiation-associated miRNAs are suggested to collectively regulate gene clusters and targets associated with enriched specific gene ontology terms or pathways. Predicted miRNA functions of this study provide novel insights into defective regulation at the transcriptomic level during myocyte proliferation and differentiation due to inflammatory stimuli.
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Affiliation(s)
- Swanhild U. Meyer
- Physiology Weihenstephan, Technische Universität München, Freising, Germany
- * E-mail:
| | - Steffen Sass
- Institute of Computational Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - Nikola S. Mueller
- Institute of Computational Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - Stefan Krebs
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefan Bauersachs
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Sebastian Kaiser
- Department of Statistics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Helmut Blum
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Sabine Krause
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Fabian J. Theis
- Institute of Computational Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
- Department of Mathematics, Technische Universität München, Garching, Germany
| | - Michael W. Pfaffl
- Physiology Weihenstephan, Technische Universität München, Freising, Germany
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Sharples AP, Hughes DC, Deane CS, Saini A, Selman C, Stewart CE. Longevity and skeletal muscle mass: the role of IGF signalling, the sirtuins, dietary restriction and protein intake. Aging Cell 2015; 14:511-23. [PMID: 25866088 PMCID: PMC4531066 DOI: 10.1111/acel.12342] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2015] [Indexed: 12/11/2022] Open
Abstract
Advancing age is associated with a progressive loss of skeletal muscle (SkM) mass and function. Given the worldwide aging demographics, this is a major contributor to morbidity, escalating socio-economic costs and ultimately mortality. Previously, it has been established that a decrease in regenerative capacity in addition to SkM loss with age coincides with suppression of insulin/insulin-like growth factor signalling pathways. However, genetic or pharmacological modulations of these highly conserved pathways have been observed to significantly enhance life and healthspan in various species, including mammals. This therefore provides a controversial paradigm in which reduced regenerative capacity of skeletal muscle tissue with age potentially promotes longevity of the organism. This paradox will be assessed and considered in the light of the following: (i) the genetic knockout, overexpression and pharmacological models that induce lifespan extension (e.g. IRS-1/s6K KO, mTOR inhibition) versus the important role of these signalling pathways in SkM growth and adaptation; (ii) the role of the sirtuins (SIRTs) in longevity versus their emerging role in SkM regeneration and survival under catabolic stress; (iii) the role of dietary restriction and its impact on longevity versus skeletal muscle mass regulation; (iv) the crosstalk between cellular energy metabolism (AMPK/TSC2/SIRT1) and survival (FOXO) versus growth and repair of SkM (e.g. AMPK vs. mTOR); and (v) the impact of protein feeding in combination with dietary restriction will be discussed as a potential intervention to maintain SkM mass while increasing longevity and enabling healthy aging.
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Affiliation(s)
- Adam P. Sharples
- Stem Cells, Ageing & Molecular Physiology Unit; Research Institute for Sport and Exercise Sciences (RISES); Exercise Metabolism and Adaptation Research Group (EMARG); Liverpool John Moores University; Tom Reilly Building Liverpool L3 3AF UK
| | - David C. Hughes
- Stem Cells, Ageing & Molecular Physiology Unit; Research Institute for Sport and Exercise Sciences (RISES); Exercise Metabolism and Adaptation Research Group (EMARG); Liverpool John Moores University; Tom Reilly Building Liverpool L3 3AF UK
- Department of Neurobiology, Physiology and Behavior; University of California; Davis California CA 95616 USA
| | - Colleen S. Deane
- MRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research; School of Medicine; University of Nottingham; Royal Derby Hospital; Derby DE22 3DT UK
- School of Health and Social Care; Bournemouth University; Bournemouth BH12 5BB UK
| | - Amarjit Saini
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm 171 77 Sweden
| | - Colin Selman
- Glasgow Ageing Research Network (GARNER); Institute of Biodiversity, Animal Health and Comparative Medicine; College of Medicine, Veterinary and Life Sciences; University of Glasgow; Glasgow G12 8QQ UK
| | - Claire E. Stewart
- Stem Cells, Ageing & Molecular Physiology Unit; Research Institute for Sport and Exercise Sciences (RISES); Exercise Metabolism and Adaptation Research Group (EMARG); Liverpool John Moores University; Tom Reilly Building Liverpool L3 3AF UK
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Radak Z, Zhao Z, Koltai E, Ohno H, Atalay M. Oxygen consumption and usage during physical exercise: the balance between oxidative stress and ROS-dependent adaptive signaling. Antioxid Redox Signal 2013; 18:1208-46. [PMID: 22978553 PMCID: PMC3579386 DOI: 10.1089/ars.2011.4498] [Citation(s) in RCA: 386] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein-protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling.
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Affiliation(s)
- Zsolt Radak
- Faculty of Physical Education and Sport Science, Institute of Sport Science, Semmelweis University, Budapest, Hungary.
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Sabin MA, Yau SW, Russo VC, Clarke IJ, Dunshea FR, Chau J, Cox M, Werther GA. Dietary monounsaturated fat in early life regulates IGFBP2: implications for fat mass accretion and insulin sensitivity. Obesity (Silver Spring) 2011; 19:2374-81. [PMID: 21436793 DOI: 10.1038/oby.2011.55] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The aim of this study was to investigate effects of dietary supplementation with fat or sugar on body composition (BC) and insulin sensitivity (IS) in maturing pigs. Fifty newborn pigs randomized to a control diet or 18% saturated fat (SF), 18% monounsaturated fat (MUF), 18% mixed fat (MF), or 50% sucrose (SUC), from 1 to 16 weeks of age. Outcomes included weight gain, BC (dual energy X-ray absorptiometry, DXA), IS (fasting insulin and hyperinsulinaemic-euglycaemic clamps), fasting Non-Esterified Fatty Acid (NEFA) concentrations, and mRNA expression of genes involved in lipogenesis and IS in skeletal muscle (SM), subcutaneous (SAT), and visceral adipose tissue (VAT). In vitro studies examined direct effects of fatty acids on insulin-like growth factor-binding protein 2 (IGFBP2) mRNA in C2C12 myotubes. While SUC-fed pigs gained most weight (due to larger quantities consumed; P < 0.01), those fed fat-enriched diets exhibited more weight gain per unit energy intake (P < 0.001). Total (P = 0.03) and visceral (P = 0.04) adiposity were greatest in MUF-fed pigs. Whole-body IS was decreased in those fed fat (P = 0.04), with fasting insulin increased in MUF-fed pigs (P = 0.03). SM IGFBP2 mRNA was increased in MUF-fed pigs (P = 0.009) and, in all animals, SM IGFBP2 mRNA correlated with total (P = 0.007) and visceral (P = 0.001) fat, fasting insulin (r = 0.321; P = 0.03) and change in NEFA concentrations (r = 0.285; P = 0.047). Furthermore, exposure of in vitro cultured myotubes to MUF, but not SF, reduced IGFBP2 mRNA suggesting a converse direct effect. In conclusion, diets high in fat, but not sugar, promote visceral adiposity and insulin resistance in maturing pigs, with evidence that fatty acids have direct and indirect effects on IGFBP2 mRNA expression in muscle.
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Affiliation(s)
- Matthew A Sabin
- Centre for Hormone Research, Murdoch Childrens Research Institute and Royal Children's Hospital, Melbourne, Victoria, Australia.
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C2 and C2C12 murine skeletal myoblast models of atrophic and hypertrophic potential: Relevance to disease and ageing? J Cell Physiol 2010; 225:240-50. [DOI: 10.1002/jcp.22252] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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10
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Use of pifithrin to inhibit p53-mediated signalling of TNF in dystrophic muscles of mdx mice. Mol Cell Biochem 2009; 337:119-31. [PMID: 19859789 DOI: 10.1007/s11010-009-0291-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 10/08/2009] [Indexed: 10/20/2022]
Abstract
Tumour Necrosis Factor (TNF) plays a major role in exacerbating necrosis of dystrophic muscle; however, the precise molecular mechanism underlying this effect of TNF is unknown. This study investigates the role that p53 plays in TNF-mediated necrosis of dystrophic myofibres by inhibiting p53 using pifithrin-alpha and three pifithrin-beta analogues. Tissue culture studies using C2C12 myoblasts established that pifithrin-alpha was toxic to differentiating myoblasts at concentrations greater than 10 muM. While non-toxic concentrations of pifithrin-alpha did not prevent the TNF-mediated inhibition of myoblast differentiation, Western blots indicated that nuclear levels of p53 were higher in TNF-treated myoblasts indicating that TNF does elevate p53. In contrast, in vivo studies in adult mdx mice showed that pifithrin-alpha significantly reduced myofibre necrosis that resulted from voluntary wheel running over 48 h. These results support the hypothesis that p53 plays some role in TNF-mediated necrosis of dystrophic muscle and present a potential new target for therapeutic interventions.
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11
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Degens H. The role of systemic inflammation in age-related muscle weakness and wasting. Scand J Med Sci Sports 2009; 20:28-38. [PMID: 19804579 DOI: 10.1111/j.1600-0838.2009.01018.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ageing is associated with a slow, but progressive muscle weakness, which is largely attributable to muscle wasting. A diminished function of satellite cells at old age may hamper preservation and repair from (contraction)-induced injury and contribute to the age-related muscle wasting. Satellite cell function may be affected by circulating factors, as muscle regeneration in old mice sharing the circulation of young mice is not impaired. Chronic low-grade systemic inflammation in old organisms may be that environmental factor. Indeed, the inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) negatively affects the muscle regenerating capacity. TNFalpha destabilizes MyoD, a muscle-specific transcription factor involved in satellite cell proliferation and differentiation, and induces apoptosis of satellite cells, particularly at old age. Here it is proposed that some of these effects are mediated by TNFalpha-induced expression of inhibitors of differentiation proteins. Yet, the increase in TNFalpha during the normal inflammatory response helps, rather than impairs, the repair process. This apparent contradiction may be resolved by the fact that the effects of TNFalpha are concentration and time dependent. Thus, the negative effect of systemic inflammation on muscle strength at old age may only become apparent when it exceeds a certain threshold and persists for a prolonged period.
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Affiliation(s)
- H Degens
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester M1 5GD, UK.
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12
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Clemmons DR. Role of IGF-I in skeletal muscle mass maintenance. Trends Endocrinol Metab 2009; 20:349-56. [PMID: 19729319 DOI: 10.1016/j.tem.2009.04.002] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 04/02/2009] [Accepted: 04/02/2009] [Indexed: 01/24/2023]
Abstract
The recent identification of signaling elements that regulate skeletal muscle protein balance has provided the opportunity to determine how IGF-I alters these processes. Animal studies have revealed the important role of IGF-I in preventing muscle atrophy and enabled investigators to determine the hierarchy of signaling pathways and events within each pathway that are modulated by IGF-I. These discoveries provide opportunity for future studies to target these important signaling events and develop strategies to reverse loss of muscle mass that accompanies these catabolic states. Because there are no approved medical therapies that will reverse catabolism at present, this represents an opportunity to fulfill a major unmet medical need.
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Affiliation(s)
- David R Clemmons
- Division of Endocrinology, University of North Carolina School of Medicine, hapel Hill, NC 27599-7170, USA.
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13
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Yang SY, Bolvin C, Sales KM, Fuller B, Seifalian AM, Winslet MC. IGF-I activates caspases 3/7, 8 and 9 but does not induce cell death in colorectal cancer cells. BMC Cancer 2009; 9:158. [PMID: 19460165 PMCID: PMC2698923 DOI: 10.1186/1471-2407-9-158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 05/21/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Colorectal cancer is the third most common cancer in the western world. Chemotherapy is often ineffective to treat the advanced colorectal cancers due to the chemo-resistance. A major contributor to chemo-resistance is tumour-derived inhibition or avoidance of apoptosis. Insulin-like growth factor I (IGF-I) has been known to play a prominent role in colorectal cancer development and progression. The role of IGF-I in cancer cell apoptosis is not completely understood. METHODS Using three colorectal cancer cell lines and one muscle cell line, associations between IGF-I and activities of caspase 3/7, 8 and 9 have been examined; the role of insulin-like growth factor I receptor (IGF-IR) in the caspase activation has been investigated. RESULTS The results show that exogenous IGF-I significantly increases activity of caspases 3/7, 8 and 9 in all cell lines used; blocking IGF-I receptor reduce IGF-I-induced caspase activation. Further studies demonstrate that IGF-I induced caspase activation does not result in cell death. This is the first report to show that while IGF-I activates caspases 3/7, 8 and 9 it does not cause colorectal cancer cell death. CONCLUSION The study suggests that caspase activation is not synonymous with apoptosis and that activation of caspases may not necessarily induce cell death.
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Affiliation(s)
- Shi Yu Yang
- University College London, Division of Surgery and Interventional Science, Royal Free & University College Medical School, Rowland Hill Street, London, UK.
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14
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Saini A, Al-Shanti N, Faulkner SH, Stewart CE. Pro- and anti-apoptotic roles for IGF-I in TNF-alpha-induced apoptosis: a MAP kinase mediated mechanism. Growth Factors 2008; 26:239-53. [PMID: 18651291 DOI: 10.1080/08977190802291634] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE The concept of skeletal muscle homeostasis--often viewed as the net balance between two separate processes, namely protein degradation and protein synthesis--are not occurring independently of each other, but are finely co-ordinated by a web of intricate signalling networks. MATERIALS AND METHODS Using rodent muscle cell lines we have investigated TNF-alpha/IGF-I interactions, in an attempt to mimic and understand mechanisms underlying the wasting process. RESULTS AND CONCLUSION When myoblast cells are incubated with TNF-alpha (10 ng ml(- 1)) maximal damage ( approximately 21% +/- 0.7 myoblast death, p < 0.05) was induced. Co-incubation of TNF-alpha (10 ng ml(- 1)) with IGF-I resulted in cell survival ( approximately 50% reduction in myoblast death, p < 0.05), however, myotube formation was not evident. In contrast, a novel role of IGF-I has been identified whereby co-incubation of muscle cells with IGF-I (1.5 ng ml(- 1)) and a non-apoptotic dose of TNF-alpha (1.25 ng ml(- 1); sufficient to block differentiation) unexpectedly were shown not to rescue a block on differentiation but to facilitate significant myoblast death (p < 0.05). Interestingly, pre-administration of PD98059, a MAPK signal-blocking agent followed by co-incubation of 1.25 ng ml(- 1) TNF-alpha and 1.5 ng ml(- 1) IGF-I, reduced death to baseline levels (p < 0.05). We show for the first time that IGF-I can be apoptotic in the absence of TNF-alpha-induced cell death.
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Affiliation(s)
- Amarjit Saini
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, UK.
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15
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Nuclear factor-kappa B signaling in skeletal muscle atrophy. J Mol Med (Berl) 2008; 86:1113-26. [PMID: 18574572 DOI: 10.1007/s00109-008-0373-8] [Citation(s) in RCA: 310] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Revised: 05/18/2008] [Accepted: 05/22/2008] [Indexed: 12/21/2022]
Abstract
Skeletal muscle atrophy/wasting is a serious complication of a wide range of diseases and conditions such as aging, disuse, AIDS, chronic obstructive pulmonary disease, space travel, muscular dystrophy, chronic heart failure, sepsis, and cancer. Emerging evidence suggests that nuclear factor-kappa B (NF-kappaB) is one of the most important signaling pathways linked to the loss of skeletal muscle mass in various physiological and pathophysiological conditions. Activation of NF-kappaB in skeletal muscle leads to degradation of specific muscle proteins, induces inflammation and fibrosis, and blocks the regeneration of myofibers after injury/atrophy. Recent studies employing genetic mouse models have provided strong evidence that NF-kappaB can serve as an important molecular target for the prevention of skeletal muscle loss. In this article, we have outlined the current understanding regarding the role of NF-kappaB in skeletal muscle with particular reference to different models of muscle wasting and the development of novel therapy.
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16
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Al-Shanti N, Saini A, Faulkner SH, Stewart CE. Beneficial synergistic interactions of TNF-alpha and IL-6 in C2 skeletal myoblasts--potential cross-talk with IGF system. Growth Factors 2008; 26:61-73. [PMID: 18428025 DOI: 10.1080/08977190802025024] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The interaction effects of tumour necrosis factor-alpha (TNF-alpha) and interlukin-6 (IL-6) on skeletal muscle proliferation and differentiation remains controversial. We therefore investigated the potential interactive effects of TNF-alpha and IL-6 on murine C2 skeletal myoblast survival, differentiation and proliferation. A novel and unexpected positive temporal interaction between TNF-alpha and IL-6 on cell growth was identified (90%), with maximal beneficial effects obtained in myoblasts treated with TNF-alpha (10 ng/ml) for 24 h prior to being dosed with IL-6 (2.5 ng/ml) for a further 24 h. This combined treatment significantly (p < 0.05) increased the level of total cellular protein (330%), extracellular signal-regulated kinase (ERK) phosphorylation (55%), and S-phase of cell cycle (2.5-fold), confirming cell growth. The expression of mRNAs of key regulators of muscle mass: insulin-like growth factor binding protein-5, insulin-like growth factor-II (IGF-II), IGF-I receptor (IGF-IR) and IGF-II receptor (IGF-IIR) were also significantly (p < 0.05) increased by 1600-, 1.6-, 27- and 6-fold, respectively, giving an indication of the regulatory mechanisms of this interaction. Moreover, in response to this treatment, the expression level of signal-transducing glycoprotein 130 (gp130) was induced up to 3.5-fold but not after either treatments alone. This may not only explain the beneficial effects of this treatment on skeletal myoblast numbers but also define a functional role of gp130 in skeletal muscle cells. Our data suggest that in the presence of TNF-alpha/IL-6 functions positively and potentially also cooperatively with the IGF system to achieve the maximal beneficial effect on skeletal myoblast numbers.
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Affiliation(s)
- Nasser Al-Shanti
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, England, UK.
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17
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Pistilli EE, Jackson JR, Alway SE. Death receptor-associated pro-apoptotic signaling in aged skeletal muscle. Apoptosis 2007; 11:2115-26. [PMID: 17051337 PMCID: PMC5271588 DOI: 10.1007/s10495-006-0194-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is elevated in the serum as a result of aging and it promotes pro-apoptotic signaling upon binding to the type I TNF receptor. It is not known if activation of this apoptotic pathway contributes to the well-documented age-associated decline in muscle mass (i.e. sarcopenia). We tested the hypothesis that skeletal muscles from aged rodents would exhibit elevations in markers involved in the extrinsic apoptotic pathway when compared to muscles from young adult rodents, thereby contributing to an increased incidence of nuclear apoptosis in these muscles. The plantaris (fast) and soleus (slow) muscles were studied in young adult (5-7 mo, n=8) and aged (33 mo, n=8) Fischer(344) x Brown Norway rats. Muscles from aged rats were significantly smaller while exhibiting a greater incidence of apoptosis. Furthermore, muscles from aged rats had higher type I TNF receptor and Fas associated death domain protein (FADD) mRNA, protein contents for FADD, BCL-2 Interacting Domain (Bid), FLICE-inhibitory protein (FLIP), and enzymatic activities of caspase-8 and caspase-3 than muscles from young adult rats. Significant correlations were observed in the plantaris muscle between caspase activity and muscle weight and the apoptotic index, while similar relationships were not found in the soleus. These data demonstrate that pro-apoptotic signaling downstream of the TNF receptor is active in aged muscles. Furthermore, our data extend the previous demonstration that type II fibers are preferentially affected by aging and support the hypothesis that type II fiber containing skeletal muscles may be more susceptible to muscle mass loses via the extrinsic apoptotic pathway.
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Affiliation(s)
- Emidio E Pistilli
- Laboratory of Muscle Biology and Sarcopenia, Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, West Virginia 26506, USA
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18
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Fu P, Thompson JA, Leeding KS, Bach LA. Insulin-like growth factors induce apoptosis as well as proliferation in LIM 1215 colon cancer cells. J Cell Biochem 2007; 100:58-68. [PMID: 16888814 DOI: 10.1002/jcb.20984] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The insulin-like growth factor (IGF) system plays an important role in cell proliferation and survival. However, more recently, a small number of studies have shown that IGFs induce apoptosis in some cells. Our initial studies showed this occurred in LIM 1215 colon cancer cells but not RD rhabdomyosarcoma cells. IGFs induced both proliferation and apoptosis in LIM 1215 cells, and the induction of apoptosis was dose-dependent. [R54, R55]IGF-II, which binds to the IGF-I receptor with normal affinity but does not bind to the IGF-II receptor, induced apoptosis to the same extent as IGF-II, whereas [L27]IGF-II, which binds to the IGF-I receptor with 1000-fold reduced affinity, had no effect on apoptosis. These results suggest that the IGF-I receptor is involved in induction of apoptosis. Western blot analyses demonstrated that Akt and Erk1/2 were constitutively activated in RD cells. In contrast, phosphorylation of Akt and Erk1/2 were transient and basal expression of Akt protein was lower in LIM 1215 cells. Analysis of apoptosis-related proteins showed that IGFs decreased pro-caspase-3 levels and increased expression of pro-apoptotic Bad in LIM 1215 cells. IGFs co-activate proliferative and apoptotic pathways in LIM 1215 cells, which may contribute to increased cell turnover. Since high turnover correlates with poor prognosis in colorectal cancer, this study provides further evidence for the role of the IGF system in its progression.
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Affiliation(s)
- Ping Fu
- Department of Medicine, Central & Eastern Clinical School, Alfred Hospital, Monash University, Prahran VIC 3181, Australia
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19
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Kurmasheva RT, Houghton PJ. IGF-I mediated survival pathways in normal and malignant cells. Biochim Biophys Acta Rev Cancer 2006; 1766:1-22. [PMID: 16844299 DOI: 10.1016/j.bbcan.2006.05.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 05/23/2006] [Accepted: 05/25/2006] [Indexed: 02/07/2023]
Abstract
The type-I and -II insulin-like growth factors (IGF-I, II) are now established as survival- or proliferation-factors in many in vitro systems. Of note IGFs provide trophic support for multiple cell types or organ cultures explanted from various species, and delay the onset of programmed cell death (apoptosis) through the mitochondrial (intrinsic pathway) or by antagonizing activation of cytotoxic cytokine signaling (extrinsic pathway). In some instances, IGFs protect against other forms of death such as necrosis or autophagy. The effect of IGFs on cell survival appears to be context specific, being determined both by the cell origin (tissue specific) and the cellular stress that induces loss of cellular viability. In many human cancers, there is a strong association with dysregulated IGF signaling, and this association has been extensively reviewed recently. IGF-regulation is also disrupted in childhood cancers as a consequence of chromosomal translocations. IGFs are implicated also in acute renal failure, traumatic injury to brain tissue, and cardiac disease. This article focuses on the role of IGFs and their cellular signaling pathways that provide survival signals in stressed cells.
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Affiliation(s)
- Raushan T Kurmasheva
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105-2794, USA
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20
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Congote LF. Monitoring insulin-like growth factors in HIV infection and AIDS. Clin Chim Acta 2005; 361:30-53. [PMID: 15970280 DOI: 10.1016/j.cccn.2005.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 05/05/2005] [Accepted: 05/06/2005] [Indexed: 01/09/2023]
Abstract
There is a close association between the growth hormone (GH)-insulin-like growth factor I (IGF-I) axis, infection and immunity. Infection with the human immunodeficiency virus (HIV) is often associated with a decrease of the concentrations of IGF-I, IGF-II, IGF-binding protein 3 (IGFBP-3) and an increase of IGFBP-1 and -2. Many investigators have studied the relationship between the GH-IGF-I system and some of the most common characteristics of disease progression, such as decreased CD4 cell counts, weight loss and fat redistribution. Although conditions for restoration of thymic function and lymphopoiesis with GH or IGF-I are still not well defined, many studies led to the development of clinical trials on the therapeutic use of GH, IGF-I and GHRH for the treatment of weight loss or fat redistribution, two problems which persist despite the introduction of highly active antiretroviral therapy. Monitoring IGF-I concentrations during treatment with GH and GHRH is likely to become an essential component of their therapeutic use. IGF-I levels are the first indicator of treatment efficacy and can be used to monitor compliance. High levels of IGF-I are a warning sign for the increased risk of potential adverse effects, such as acromegalic-like symptoms or malignancy. This could lead to a reduction of the therapeutic dose or the temporary interruption of treatment until IGF levels reach a safe range. IGF-I levels are also likely to increase with other hormones used in HIV patients, such as erythropoietin for the treatment of anemia or anabolic androgens in HIV-infected women.
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Affiliation(s)
- Luis F Congote
- Endocrine Laboratory, Rm. L2.05, McGill University Health Centre, Montreal, Québec, Canada H3A 1A1.
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21
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Remacle-Bonnet M, Garrouste F, Baillat G, Andre F, Marvaldi J, Pommier G. Membrane rafts segregate pro- from anti-apoptotic insulin-like growth factor-I receptor signaling in colon carcinoma cells stimulated by members of the tumor necrosis factor superfamily. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 167:761-73. [PMID: 16127155 PMCID: PMC1698735 DOI: 10.1016/s0002-9440(10)62049-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In the tumor microenvironment, autocrine/paracrine loops of insulin-like growth factors (IGFs) contribute to cancer cell survival. However, we report here that IGF-I can send contradictory signals that interfere with cell death induced by different ligands of the tumor necrosis factor (TNF) superfamily. IGF-I protected human colon carcinoma cells from TNF-alpha-induced apoptosis, but it enhanced the apoptotic response to anti-Fas antibody and TNF-related apoptosis inducing ligand stimulation. This proapoptotic effect of IGF-I, observed in several but not all tested colon cancer cell lines, was mediated via the phosphatidylinositol 3'-kinase (PI3K)/Akt pathway. Furthermore, IGF-I receptors (IGF-IR) were located in and out of membrane lipid rafts and were tyrosine autophosphorylated in response to IGF-I. However, disruption of rafts by acute cholesterol depletion shifted IGF-IR to non-raft domains, abolished the IGF-I-mediated proapoptotic effect, and inhibited the IGF-I-dependent IRS-1 and Akt recruitment into and phosphorylation/activation within lipid rafts. Replenishing cell membranes with cholesterol reversed these effects. Activation of extracellular-regulated kinase-1/2 and p38 mitogen-activated protein kinase, which convey the IGF-I anti-apoptotic effect, occurred independently of lipid rafts. Thus, we propose that segregation of IGF-IR in and out of lipid rafts may dynamically regulate the pro- and anti-apoptotic effects of IGF-I on apoptosis induced by TNF superfamily members.
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Affiliation(s)
- Maryse Remacle-Bonnet
- FRE CNRS 27.37, Faculté de Pharmacie, 27 Bd. Jean Moulin, 13385 Marseille Cedex 5, France.
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22
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Tolosa L, Morlá M, Iglesias A, Busquets X, Lladó J, Olmos G. IFN-γ prevents TNF-α-induced apoptosis in C2C12 myotubes through down-regulation of TNF-R2 and increased NF-κB activity. Cell Signal 2005; 17:1333-42. [PMID: 16125053 DOI: 10.1016/j.cellsig.2005.02.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Accepted: 02/04/2005] [Indexed: 01/24/2023]
Abstract
Wasting of skeletal muscle (cachexia) is associated with a variety of chronic or inflammatory disorders and has long been recognized as a poor prognostic sign. It is currently accepted that the cytokine tumor necrosis factor alpha (TNF-alpha; cachectin) plays a key role in the development of this condition. TNF-alpha-induced apoptotic cell death represents a potential mechanism by which muscle wasting can occur. Evidence has accumulated that the cytokine interferon gamma (IFN-gamma) may act as a modulator of TNF-alpha signalling. Thus, the present study was designed to elucidate if TNF-alpha can directly induce apoptosis in differentiated myotubes, to assess the potential anti-apoptotic properties of IFN-gamma and to get insight into the signalling pathways implicated in the modulatory effects of IFN-gamma. Myoblasts of the murine cell line C2C12 were allowed to differentiate in a low serum containing media and myogenesis assessed by muscle specific protein expression. Non-proliferating, polynucleated, fully differentiated myotubes were obtained after seven days in differentiation media. Exposure of C2C12 myotubes to TNF-alpha for 48 h induced apoptosis characterized by enhanced caspase-3 activity, which resulted in poly(ADP-ribose) polymerase (PARP) cleavage and increased histone-associated-DNA fragmentation. These effects were fully reverted in the presence of IFN-gamma. This cytokine induced down-regulation of the subtype 2 of TNF-alpha receptors (TNF-R2), enhanced TNF-alpha-induced NF-kappaB translocation to the nucleus and binding to DNA and increased the immunoreactivity of the protein c-IAP1, a member of the inhibitor of apoptosis (IAP) gene family whose synthesis is stimulated by NF-kappaB at the transcriptional level. Together, these results demonstrate that TNF-alpha directly induces apoptosis in differentiated myotubes and suggest that the cytokine IFN-gamma, might represent a new immunoadjuvant therapeutic tool for managing cachexia.
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Affiliation(s)
- Laia Tolosa
- Institut Universitari d'Investigacions en Ciències de la Salut/Departament de Biologia, Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
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23
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Shumilina E, Lampert A, Lupescu A, Myssina S, Strutz-Seebohm N, Henke G, Grahammer F, Wulff P, Kuhl D, Lang F. Deranged Kv channel regulation in fibroblasts from mice lacking the serum and glucocorticoid inducible kinase SGK1. J Cell Physiol 2005; 204:87-98. [PMID: 15605386 DOI: 10.1002/jcp.20267] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Coexpression of the serum and glucocorticoid inducible kinase 1 (SGK1) up-regulates Kv channel activity in Xenopus oocytes and human embryonic kidney cells. To investigate the physiological impact of SGK1 dependent Kv channel regulation, we recorded whole-cell currents in lung fibroblasts from SGK1 knockout mice (sgk1-/-) and wild-type littermates (sgk1+/+). Serum-grown mouse lung fibroblasts (MLF) from both genotypes exhibited voltage-gated outwardly rectifying K(+)-currents with time-dependent activation (tau(act) approximately 3 msec), slow inactivation (tau(inact) approximately 700 msec), use-dependent inactivation, and (partial) inhibition by K(+) channel blockers TEA, 4-AP, and margatoxin. In serum grown MLF peak Kv current density at +100 mV was significantly lower in sgk1-/- (14 +/- 2 pA/pF, n = 13) than in sgk1+/+ (31 +/- 4 pA/pF, n = 16). PCR amplification of different Kv1 and Kv3 subunits from mouse fibroblasts demonstrated the expression of Kv1.1-1.7, Kv3.1, and Kv3.3 mRNA in both sgk1+/+ and sgk1-/- cells. Upon serum deprivation Kv currents almost disappeared in sgk1+/+ (4 +/- 1 pA/pF, n = 11) but not in sgk1-/- (10 +/- 1 pA/pF, n = 6) MLF. Accordingly, following serum deprivation Kv current density was significantly lower in sgk1+/+ than in sgk1-/-. Stimulation of serum-depleted cells with dexamethasone (dex) (1 microM, 1 day), IGF-1 (6.7 microM, 4-6 h) or both, significantly activated Kv currents in sgk1+/+ but not in sgk1-/- MLF. In the presence of both, dex and IGF-1, the Kv current density was significantly larger in sgk1+/+ (27 +/- 3 pA/pF, n = 12) than in sgk1-/- (13 +/- 3 pA/pF, n = 10) cells. Similar to MLF, Kv currents were significantly higher in sgk1+/+ mouse tail fibroblasts (MTF). In sgk1+/+ but not sgk1-/- MTF the Kv currents were inhibited upon serum deprivation and reincreased after stimulation of serum deprived MTF with dex (1 microM, 1 day) and afterwards with IGF-1 (6.7 microM, 4-6 h). According to Fura-2-fluorescence capacitative Ca(2+) entry was lower in sgk1-/- MTF compared to sgk1+/+ MTF. Upon serum deprivation capacitative Ca(2+) entry decreased significantly in sgk1+/+ but not in sgk1-/- MTF. Stimulation of depleted cells with dex (1 microM, 1 day) and afterwards with IGF-1 (6.7 microM, 4-6 h) reincreased capacitative Ca(2+) entry in sgk1+/+ MTF, whereas in sgk1-/- cells it remained unchanged. In conclusion, lack of SGK1 does not abrogate Kv channel activity but abolishes regulation of those channels by serum, glucocorticoids and IGF-1, an effect influencing capacitative Ca(2+) entry.
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Brimah K, Ehrhardt J, Mouly V, Butler-Browne GS, Partridge TA, Morgan JE. Human muscle precursor cell regeneration in the mouse host is enhanced by growth factors. Hum Gene Ther 2005; 15:1109-24. [PMID: 15610611 DOI: 10.1089/hum.2004.15.1109] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The aim of this study was to optimize human muscle formation in vivo from implanted human muscle precursor cells. We transplanted donor muscle precursor cells (MPCs) prepared from postnatal or fetal human muscle into immunodeficient host mice and showed that irradiation of host muscle significantly enhanced muscle formation by donor cells. The amount of donor muscle formed in cryodamaged host muscle was increased by exposure of donor cells to growth factors before their implantation into injured host muscle. Insulin-like growth factor type I (IGF-I) significantly increased the amount of muscle formed by postnatal human muscle cells, but not by fetal human MPCs. However, treatment of fetal muscle cells with IGF-I, in combination with basic fibroblast growth factor and plasmin, significantly increased the amount of donor muscle formed. In vivo, human MPCs formed mosaic human-mouse muscle fibers, in which each human myonucleus was associated with a zone of human sarcolemmal protein spectrin.
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Affiliation(s)
- K Brimah
- Muscle Cell Biology Group, MRC Clinical Sciences Centre, Imperial College, London W12 ONN, United Kingdom
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25
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Abstract
Sarcopenia, loss of skeletal muscle mass, is a hallmark of aging commonly attributed to a decreased capacity to maintain muscle tissue in senescence, yet the mechanism behind the muscle wasting remains unresolved. To address these issues we have explored a rodent model of sarcopenia and age-related sensorimotor impairment, allowing us to discriminate between successfully and unsuccessfully aged cohort members. Immunohistochemistry and staining of cell nuclei revealed that senescent muscle has an increased density of cell nuclei, occurrence of aberrant fibers and fibers expressing embryonic myosin. Using real-time PCR we extend the findings of increased myogenic regulatory factor mRNA to show that very high levels are found in unsuccessfully aged cohort members. This pattern is also reflected in the number of embryonic myosin-positive fibers, which increase with the degree of sarcopenia. In addition, we confirm that there is no local down-regulation of IGF-I and IGF-IR mRNA in aged muscle tissue; on the contrary, the most sarcopenic individuals showed significantly higher local expression of IGF-I mRNA. Combined, our results show that the initial drive to regenerate myofibers is most marked in cases with the most advanced loss of muscle mass, a pattern that may have its origin in differences in the rate of tissue deterioration and/or that regenerating myofibers in these cases fail to mature into functional fibers. Importantly, the genetic background is a determinant of the pace of progression of sarcopenia.
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Affiliation(s)
- Erik Edström
- Experimntal Neurogerontology, Department of Neuroscience, Karolinska Institutet, S171 77 Stockholm, Sweden.
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26
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Tannu NS, Rao VK, Chaudhary RM, Giorgianni F, Saeed AE, Gao Y, Raghow R. Comparative Proteomes of the Proliferating C2C12 Myoblasts and Fully Differentiated Myotubes Reveal the Complexity of the Skeletal Muscle Differentiation Program. Mol Cell Proteomics 2004; 3:1065-82. [PMID: 15286212 DOI: 10.1074/mcp.m400020-mcp200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
When cultured in low serum-containing growth medium, the mouse C(2)C(12) cells exit cell cycle and undergo a well-defined program of differentiation that culminates in the formation of myosin heavy chain-positive bona fide multinucleated muscle cells. To gain an understanding into this process, we compared total, membrane- and nuclear-enriched proteins, and phospho-proteins from the proliferating C(2)C(12) cells and the fully differentiated myotubes by the combined methods of two-dimensional PAGE, quantitative PDQuest image analysis, and MS. Quantification of more than 2,000 proteins from C(2)C(12) myoblasts and myotubes revealed that a vast majority of the abundant proteins appear to be relegated to the essential, housekeeping and structural functions, and their steady state levels remain relatively constant. In contrast, 75 proteins were highly regulated during the phenotypic conversion of rapidly dividing C(2)C(12) myoblasts into fully differentiated, multi-nucleated, post-mitotic myotubes. We found that differential accumulation of 26 phospho-proteins also occurred during conversion of C(2)C(12) myoblasts into myotubes. We identified the differentially expressed proteins by MALDI-TOF-MS and LC-ESI-quadrupole ion trap MS/MS. We demonstrate that more than 100 proteins, some shown to be associated with muscle differentiation for the first time, that regulate inter- and intracellular signaling, cell shape, proliferation, apoptosis, and gene expression impinge on the mechanism of skeletal muscle differentiation.
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Affiliation(s)
- Nilesh S Tannu
- Departments of Biomedical Engineering, University of Tennessee Health Science Center, Memphis, TN 38104, USA
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Sorci G, Riuzzi F, Arcuri C, Giambanco I, Donato R. Amphoterin stimulates myogenesis and counteracts the antimyogenic factors basic fibroblast growth factor and S100B via RAGE binding. Mol Cell Biol 2004; 24:4880-94. [PMID: 15143181 PMCID: PMC416409 DOI: 10.1128/mcb.24.11.4880-4894.2004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The receptor for advanced glycation end products (RAGE), a multiligand receptor of the immunoglobulin superfamily, has been implicated in the inflammatory response, diabetic angiopathy and neuropathy, neurodegeneration, cell migration, tumor growth, neuroprotection, and neuronal differentiation. We show here that (i) RAGE is expressed in skeletal muscle tissue and its expression is developmentally regulated and (ii) RAGE engagement by amphoterin (HMGB1), a RAGE ligand, in rat L6 myoblasts results in stimulation of myogenic differentiation via activation of p38 mitogen-activated protein kinase (MAPK), up-regulation of myogenin and myosin heavy chain expression, and induction of muscle creatine kinase. No such effects were detected in myoblasts transfected with a RAGE mutant lacking the transducing domain or myoblasts transfected with a constitutively inactive form of the p38 MAPK upstream kinase, MAPK kinase 6, Cdc42, or Rac-1. Moreover, amphoterin counteracted the antimyogenic activity of the Ca(2+)-modulated protein S100B, which was reported to inhibit myogenic differentiation via inactivation of p38 MAPK, and basic fibroblast growth factor (bFGF), a known inhibitor of myogenic differentiation, in a manner that was inversely related to the S100B or bFGF concentration and directly related to the extent of RAGE expression. These data suggest that RAGE and amphoterin might play an important role in myogenesis, accelerating myogenic differentiation via Cdc42-Rac-1-MAPK kinase 6-p38 MAPK.
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Affiliation(s)
- Guglielmo Sorci
- Department of Experimental Medicine and Biochemical Sciences, Section of Anatomy, University of Perugia, Via del Giochetto C.P. 81 Succ. 3, 06122 Perugia, Italy
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28
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Henke G, Maier G, Wallisch S, Boehmer C, Lang F. Regulation of the voltage gated K+ channel Kv1.3 by the ubiquitin ligase Nedd4-2 and the serum and glucocorticoid inducible kinase SGK1. J Cell Physiol 2004; 199:194-9. [PMID: 15040001 DOI: 10.1002/jcp.10430] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The stimulation of cell proliferation by insulin like growth factor IGF-1 has previously been shown to depend on activation of voltage gated K(+) channels. The signaling involved in activation of voltage gated K(+) channel Kv1.3 includes the phosphatidylinositol-3 (PI3) protein kinase, 3-phosphoinositide dependent protein kinase PDK1 and the serum and glucocorticoid inducible kinase SGK1. However, nothing is known about mechanisms mediating the stimulation of Kv1.3 by SGK1. Most recently, SGK1 has been shown to phosphorylate and thus inactivate the ubiquitin ligase Nedd4-2. The present study has been performed to explore whether the regulation of Kv1.3 involves Nedd4-2. To this end Kv1.3 has been expressed in Xenopus oocytes with or without coexpression of Nedd4-2 and/or constitutively active (S422D)SGK1. In oocytes expressing Kv1.3 but not in water injected oocytes, depolarization from a holding potential of -80 mV to +20 mV triggers rapidly inactivating currents typical for Kv1.3. Coexpression of Nedd4-2 decreases, coexpression of (S422D)SGK1 enhances the currents significantly. The effects of either Nedd4-2 or of SGK1 are abrogated by destruction of the respective catalytic subunits ((C938S)Nedd4-2 or (K127N)SGK1). Further experiments revealed that wild type SGK1 and SGK3 and to a lesser extent SGK2 are similarly effective in stimulating Kv1.3 in both, presence and absence of Nedd4-2. It is concluded that Kv1.3 is downregulated by Nedd4-2 and stimulates by SGK1, SGK2, and SGK3. The data thus disclose a novel mechanism of Kv1.3 channel regulation.
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Affiliation(s)
- G Henke
- Department of Physiology, University of Tubingen, Tubingen, Germany
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29
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Fischer-Posovszky P, Tornqvist H, Debatin KM, Wabitsch M. Inhibition of death-receptor mediated apoptosis in human adipocytes by the insulin-like growth factor I (IGF-I)/IGF-I receptor autocrine circuit. Endocrinology 2004; 145:1849-59. [PMID: 14691011 DOI: 10.1210/en.2003-0985] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Adipose tissue mass is reflected by the volume and the number of adipocytes and is subject to homeostatic regulation involving cell death mechanisms. In this study we have investigated the mechanisms of apoptosis in human preadipocytes and adipocytes that may play a role in the regulation of adipose tissue mass. We found that death receptors (CD95, TNF-related apoptosis-inducing ligand receptors 1 and 2, and TNF receptor 1) are expressed in human fat cells and that apoptosis can be induced by specific ligands. Sensitivity to apoptosis could be stimulated by an inhibitor of biosynthesis. In addition, inhibition of auto-/paracrine action of IGF-I dramatically sensitizes human adipocytes for death ligand-induced apoptosis. Phosphoinositide 3-kinase and, to a weaker extent, p38 MAPK are involved in IGF-I-mediated survival. IGF-I protects human fat cells from apoptosis by maintaining the expression of antiapoptotic proteins, Bcl-x(L) and Fas-associated death domain-like IL-1-converting enzyme inhibitory protein. In conclusion, we identified mechanisms of apoptosis induction in human fat cells. We furthermore demonstrate that human fat cells protect themselves from apoptosis by IGF-I in an auto-/paracrine manner.
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30
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Foulstone EJ, Huser C, Crown AL, Holly JMP, Stewart CEH. Differential signalling mechanisms predisposing primary human skeletal muscle cells to altered proliferation and differentiation: roles of IGF-I and TNFalpha. Exp Cell Res 2004; 294:223-35. [PMID: 14980516 DOI: 10.1016/j.yexcr.2003.10.034] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Revised: 09/24/2003] [Indexed: 10/26/2022]
Abstract
To gain a clearer insight into the mechanisms of skeletal muscle cell growth, differentiation and maintenance, we have developed a primary adult human skeletal muscle cell model. Cells were cultured from biopsies of rectus muscle from the anterior abdominal wall of patients undergoing elective surgery. Under differentiating conditions, all cultures formed myotubes, irrespective of initial myoblast number. Stimulation with both IGF-I and tumour necrosis factor alpha (TNFalpha) increased cellular proliferation but while IGF-I subsequently increased myoblast differentiation, via both hyperplasia and hypertrophy, TNFalpha inhibited the initiation of differentiation, but did not induce apoptosis. Addition of IGF-I stimulated both the MAP kinase and the phosphatidylinositide 3-kinase (PI 3-kinase) signalling pathways while treatment with TNFalpha preferentially led to MAP kinase activation although with a very different profile of activation compared to IGF-I. Data using the MEK inhibitor UO126 showed MAP kinase activity is not only needed for cellular proliferation but is also necessary for both the initiation and the progression of primary human myoblast differentiation. The PI 3-kinase pathway is also involved in differentiation, but activation of this pathway could not relieve inhibition of differentiation by TNFalpha or UO126. Our results show that the controlled temporal and amplitude of activation of multiple signalling pathways is needed for successful myoblast differentiation.
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Affiliation(s)
- Emily J Foulstone
- Division of Surgery, University of Bristol, Bristol Royal Infirmary, Bristol, BS2 8HW, UK.
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Stewart CEH, Newcomb PV, Holly JMP. Multifaceted roles of TNF-alpha in myoblast destruction: a multitude of signal transduction pathways. J Cell Physiol 2004; 198:237-47. [PMID: 14603526 DOI: 10.1002/jcp.10387] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In catabolic conditions, such as cancer cachexia, a balance favouring a cytokine environment culminates in muscle destruction. Utilising an in vitro model to mimic muscle wasting, we elucidate here the multifaceted roles that one such cytokine, TNF-alpha, invokes in the degeneration process. Treatment of C2 skeletal myoblasts with TNF-alpha not only suppresses morphological and biochemical differentiation, but following an initial wave of proliferation, and of survival (24 h), induces apoptosis. Investigating the mechanisms underlying these diverse actions of TNF-alpha, we demonstrate that cell replication is dependent on rapid and sustained activation of MAP kinase. Map kinase is not, however, central to the death process, which is associated with a progressive rise in caspase-8 activity, and is accompanied by sustained activation of JNK1 and transient activation of JNK2. Caspase inhibition caused a dose responsive reduction in cell death, while inhibition of the JNKs caused a significant increase in apoptosis. We further report that PI3 kinase is not involved in conferring early protection against TNF-alpha-induced death. By contrast, inhibition of NF-kappaB in the presence of TNF-alpha culminates in increased cell cycle progression, decreased gadd45beta expression and significant and precociously increased cell death, when compared with TNF-alpha alone. Our results begin to characterise the mechanisms underlying the acute mitogenic and anti-apoptotic roles of TNF-alpha, which appear to be defined by a balance between MAP kinase, Jun kinase (JNK), NF-kappaB and gadd45beta. They establish that inhibition of any one of these molecules, as may occur following caspase activation, could eliminate vital stem cells required for skeletal muscle regeneration during chronic catabolic conditions.
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Affiliation(s)
- C E H Stewart
- University Department of Surgery, Level 7, Bristol Royal Infirmary, Bristol, England, United Kingdom.
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32
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Broussard SR, McCusker RH, Novakofski JE, Strle K, Shen WH, Johnson RW, Freund GG, Dantzer R, Kelley KW. Cytokine-hormone interactions: tumor necrosis factor alpha impairs biologic activity and downstream activation signals of the insulin-like growth factor I receptor in myoblasts. Endocrinology 2003; 144:2988-96. [PMID: 12810554 DOI: 10.1210/en.2003-0087] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TNFalpha is elevated following damage to skeletal muscle. Here we provide evidence that TNFalpha acts on muscle cells to induce a state of IGF-I receptor resistance. We establish that TNFalpha inhibits IGF-I-stimulated protein synthesis in primary porcine myoblasts. Similar results were observed in C(2)C(12) murine myoblasts, where as little as 0.01 ng/ml TNFalpha significantly inhibits protein synthesis induced by IGF-I. TNFalpha also impairs the ability of IGF-I to induce expression of a key myogenic transcription factor, myogenin. The inhibition by TNFalpha of IGF-I-induced protein synthesis and expression of myogenin is not due to direct killing of myoblasts by TNFalpha. Although IGF-I induces an approximately 19-fold induction in tyrosine phosphorylation of the beta-chains of its receptor, TNFalpha does not inhibit this autophosphorylation. Instead, TNFalpha significantly reduces by approximately 50% IGF-I-stimulated tyrosine phosphorylation of two of the major downstream receptor docking molecules, insulin receptor substrate (IRS)-1 and IRS-2. These results establish that low picogram concentrations of TNFalpha acts on both porcine and murine myoblasts to impair tyrosine phosphorylation of both IRS-1 and IRS-2, but not the receptor itself. These data are consistent with the notion that very low physiological concentrations of TNFalpha interfere with both protein synthesis and muscle cell development by inducing a state of IGF-I receptor resistance.
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Affiliation(s)
- Suzanne R Broussard
- Laboratory of Immunophysiology, Department of Animal Sciences and Pathology, College of Medicine, University of Illinois at Urbana-Champaign, 207 Edward R. Madigan Laboratory, 1201 West Gregory Drive, Urbana, IL 61801, USA.
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Foulstone EJ, Savage PB, Crown AL, Holly JMP, Stewart CEH. Role of insulin-like growth factor binding protein-3 (IGFBP-3) in the differentiation of primary human adult skeletal myoblasts. J Cell Physiol 2003; 195:70-9. [PMID: 12599210 DOI: 10.1002/jcp.10227] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Although muscle satellite cells were identified almost 40 years ago, little is known about the induction of their proliferation and differentiation in response to physiological/pathological stimuli or to growth factors/cytokines. In order to investigate the role of the insulin-like growth factor (IGF)/IGF binding protein (IGFBP) system in adult human myoblast differentiation we have developed a primary human skeletal muscle cell model. We show that under low serum media (LSM) differentiating conditions, the cells secrete IGF binding proteins-2, -3, -4 and -5. Intact IGFBP-5 was detected at days 1 and 2 but by day 7 in LSM it was removed by proteolysis. IGFBP-4 levels were also decreased at day 7 in the presence of IGF-I, potentially by proteolysis. In contrast, we observed that IGFBP-3 initially decreased on transfer of cells into LSM but then increased with myotube formation. Treatment with 20 ng/ml tumour necrosis factor-alpha (TNFalpha), which inhibits myoblast differentiation, blocked IGFBP-3 production and secretion whereas 30 ng/ml IGF-I, which stimulates myoblast differentiation, increased IGFBP-3 secretion. The TNFalpha-induced decrease in IGFBP-3 production and inhibition of differentiation could not be rescued by addition of IGF-I. LongR(3)IGF-I, which does not bind to the IGFBPs, had a similar effect on differentiation and IGFBP-3 secretion as IGF-I, both with and without TNFalpha, confirming that increased IGFBP-3 is not purely due to increased stability conferred by binding to IGF-I. Furthermore reduction of IGFBP-3 secretion using antisense oligonucleotides led to an inhibition of differentiation. Taken together these data indicate that IGFBP-3 supports myoblast differentiation.
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Affiliation(s)
- Emily J Foulstone
- Division of Surgery, University of Bristol, Bristol Royal Infirmary, Bristol, England.
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Galvin CD, Hardiman O, Nolan CM. IGF-1 receptor mediates differentiation of primary cultures of mouse skeletal myoblasts. Mol Cell Endocrinol 2003; 200:19-29. [PMID: 12644296 DOI: 10.1016/s0303-7207(02)00420-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Studies involving immortalized myoblasts suggested that insulin-like growth factors (IGFs) promote differentiation of skeletal muscle, but gene targeting experiments in mice did not provide support for this hypothesis. To address this discrepancy, we examined differentiation of primary cultures of mouse myoblasts. Differentiation was normally unaffected by addition of IGFs to the differentiation medium. However, when we interrupted IGF-mediated signaling, by incubating myoblasts with suramin or with a monoclonal antibody to the IGF-I receptor, differentiation was inhibited. Inhibition was reversed by exogenous IGF-I or IGF-II, but not by insulin. Differentiation was enhanced in myoblasts that were incubated with an inhibitor of the mitogen-activated protein kinase signaling pathway (PD098059) and such cells were responsive to exogenous IGF-I. Our results demonstrate that IGF action contributes to the differentiation of non-immortalized mouse myoblasts and that these cells represent a model system that can be experimentally manipulated to study the molecular events involved in skeletal muscle differentiation.
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Affiliation(s)
- C D Galvin
- Zoology Department, University College Dublin, Belfield, Ireland
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Shen X, Collier JM, Hlaing M, Zhang L, Delshad EH, Bristow J, Bernstein HS. Genome-wide examination of myoblast cell cycle withdrawal during differentiation. Dev Dyn 2003; 226:128-38. [PMID: 12508234 DOI: 10.1002/dvdy.10200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Skeletal and cardiac myocytes cease division within weeks of birth. Although skeletal muscle retains limited capacity for regeneration through recruitment of satellite cells, resident populations of adult myocardial stem cells have not been identified. Because cell cycle withdrawal accompanies myocyte differentiation, we hypothesized that C2C12 cells, a mouse myoblast cell line previously used to characterize myocyte differentiation, also would provide a model for studying cell cycle withdrawal during differentiation. C2C12 cells were differentiated in culture medium containing horse serum and harvested at various time points to characterize the expression profiles of known cell cycle and myogenic regulatory factors by immunoblot analysis. BrdU incorporation decreased dramatically in confluent cultures 48 hr after addition of horse serum, as cells started to form myotubes. This finding was preceded by up-regulation of MyoD, followed by myogenin, and activation of Bcl-2. Cyclin D1 was expressed in proliferating cultures and became undetectable in cultures containing 40% fused myotubes, as levels of p21(WAF1/Cip1) increased and alpha-actin became detectable. Because C2C12 myoblasts withdraw from the cell cycle during myocyte differentiation following a course that recapitulates this process in vivo, we performed a genome-wide screen to identify other gene products involved in this process. Using microarrays containing approximately 10,000 minimally redundant mouse sequences that map to the UniGene database of the National Center for Biotechnology Information, we compared gene expression profiles between proliferating, differentiating, and differentiated C2C12 cells and verified candidate genes demonstrating differential expression by RT-PCR. Cluster analysis of differentially expressed genes revealed groups of gene products involved in cell cycle withdrawal, muscle differentiation, and apoptosis. In addition, we identified several genes, including DDAH2 and Ly-6A, whose expression specifically was up-regulated during cell cycle withdrawal coincident with early myoblast differentiation.
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Affiliation(s)
- Xun Shen
- Cardiovascular Research Institute, University of California, San Francisco, California, USA
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Bakay M, Zhao P, Chen J, Hoffman EP. A web-accessible complete transcriptome of normal human and DMD muscle. Neuromuscul Disord 2002; 12 Suppl 1:S125-41. [PMID: 12206807 DOI: 10.1016/s0960-8966(02)00093-7] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present an assessment of the complete transcriptome of human skeletal muscle in Duchenne muscular dystrophy patient muscle and non-dystrophic controls (36 RNAs analyzed from ten Duchenne dystrophy and eight controls; approximately 65,000 gene/expressed sequence tag/probe sets queried on U95 five-GeneChip series and MuscleChip). The use of the multiple chip types allowed us to compare results from different probe sets for the same gene: we found excellent concordance between different probe sets on different microarrays. We found 30% of human genes expressed in muscle at detectable levels. Three percent of these showed differential regulation in dystrophin deficiency. Among 1,882 dysregulated probe sets, 1,324 corresponded to characterized genes/proteins (891 non-redundant transcript units), and 588 to expressed sequence tags or predicted genes. Data interpretation was limited to the insulin-like growth factor pathway members, an investigation of possible de-regulation towards a cardiac lineage, and identification of male- and female-specific transcripts. We found transcriptional upregulation of both IGF-I and IGF-II in dystrophic muscle, however the possible beneficial effects of the growth factors appear offset by transcriptional upregulation of inhibitory IGF-binding proteins and regulators (IGFBP-2, -4, -6 and -7; and PRSS11 [IGFBP-5 protease]). We hypothesize that the beneficial effects of IGF-I or IGF-II supplementation in dystrophic muscle may be the result of dose-dependent sequestration of inhibitory IGF-binding proteins. We also focused on six 'cardiac' genes expressed in muscle (alpha-cardiac actin, CARP, CASQ2, troponin T2 cardiac [TNNT2], CUGBP2, and connexin 43). Comparison to a 27 time point murine muscle regeneration series and mdx muscle profiles showed that CARP and Cx43 were macrophage-associated, and TNNT2 activated-myoblast-associated. Upregulation of cardiac actin and CUGBP2 was not associated with muscle regeneration profiles, suggesting a more specific dysregulation induced by dystrophin deficiency. We found two Y-linked genes expressed solely in male muscle (RPS4Y, DDX3Y), and two autosomal genes expressed much more highly in female muscle (GRO2, ZNF91) (all comparisons P<0.01). Finally, we present the first web-accessible expression profiling database for all data, including image files (.dat), processed image files (.cel), and complete comparison files which are publicly available through a novel queriable web site, that permits query-by-gene across all profiles (http://microarray.cnmcresearch.org/pga). These data enumerate the full range of molecular changes associated downstream of dystrophin deficiency, and provide a web-accessible platform to study the specificity of transcriptional pathway alterations in muscle disease.
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Affiliation(s)
- Marina Bakay
- Research Center for Genetic Medicine, George Washington University School of Medicine, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA
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