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Milingos DS, Philippou A, Armakolas A, Papageorgiou E, Sourla A, Protopapas A, Liapi A, Antsaklis A, Mastrominas M, Koutsilieris M. Insulinlike growth factor-1Ec (MGF) expression in eutopic and ectopic endometrium: characterization of the MGF E-peptide actions in vitro. Mol Med 2010; 17:21-8. [PMID: 20844834 DOI: 10.2119/molmed.2010.00043] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 09/12/2010] [Indexed: 11/06/2022] Open
Abstract
The transcription of the insulinlike growth factor 1 (igf-1) gene generates three mRNA isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (or MGF [mechano growth factor]). Herein, we analyzed the expression of IGF-1 isoforms in eutopic and ectopic endometrium (red lesions and endometriotic cysts) of women with endometriosis, and we characterized the actions of a synthetic MGF E-peptide on KLE cells. Our data documented that all three igf-1 gene transcripts are expressed in the stromal cells of the eutopic and ectopic endometrium; however, endometriotic cysts contained significantly lower IGF-1 isoform expression, both at the mRNA and protein level, as was shown using semiquantitative PCR and immunohistochemical methods. In addition, the glandular cells of the eutopic endometrium did not express any of the IGF-1 isoforms; however, the glandular cells of the ectopic endometrium (red lesions) did express the IGF-1Ec at mRNA and protein level. Furthermore, synthetic MGF E-peptide, which comprised the last 24 amino acids of the MGF, stimulated the growth of the KLE cells. Experimental silencing of the type 1 IGF receptor (IGF-1R) and insulin receptor expression of KLE cells (siRNA knock-out methods) did not alter the mitogenic action of the synthetic MGF E-peptide, revealing that MGF E-peptide stimulates the growth of KLE cells via an IGF-1R-independent and insulin receptor-independent mechanism. These data suggest that the IGF-1Ec transcript might generate, apart from mature IGF-1 peptide, another posttranslational bioactive product that may have an important role in endometriosis pathophysiology.
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Affiliation(s)
- Dimitrios S Milingos
- Department of Experimental Physiology, National and Kapodistrian University of Athens, Goudi-Athens, Greece
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52
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GH overexpression causes muscle hypertrophy independent from local IGF-I in a zebrafish transgenic model. Transgenic Res 2010; 20:513-21. [DOI: 10.1007/s11248-010-9429-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Accepted: 07/07/2010] [Indexed: 01/29/2023]
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Temmerman L, Slonimsky E, Rosenthal N. Class 2 IGF-1 isoforms are dispensable for viability, growth and maintenance of IGF-1 serum levels. Growth Horm IGF Res 2010; 20:255-263. [PMID: 20382057 DOI: 10.1016/j.ghir.2010.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 02/09/2010] [Accepted: 03/07/2010] [Indexed: 12/17/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) is a pleiotropic factor involved in growth, cell survival and cellular differentiation. It exerts its functions through endocrine, paracrine or autocrine mechanisms. Circulating IGF-1 is essential for normal fetal and postnatal growth, although the published phenotypes of IGF-1 null animals have been only partially penetrant, presumably due to mixed genetic backgrounds. Molecular dissection of IGF-1 action is complicated by the existence of at least nine different IGF-1 isoforms, generated in both humans and rodents by usage of alternate promoters, differential splicing and different post-translational modifications. Several lines of evidence suggest that the Class 2 IGF-1 isoform is specifically destined for circulation, supporting an endocrine role of IGF-1 in normal growth processes. Using Cre/LoxP conditional gene targeting of exon 2 of the IGF-1 gene, we have generated a Class 2 IGF-1 knockout mouse line in a pure C57/Bl6 genetic background, where the specific removal of exon 2 ablated Class 2 IGF-1 isoform. Class 2 IGF-1 knockout mice exhibited normal development and postnatal growth patterns and had normal IGF-1 circulating levels, due to compensatory upregulation of Class 1 transcripts. In contrast, progeny of a total IGF-1 knockout line lacking exon 3 in the same genetic background were predictably smaller, displayed dramatically reduced IGF-1 receptor phosphorylation and all died perinatally, apparently due to respiratory failure. These results confirm that Class 2 signal peptide is not necessary for systemic circulation of IGF-1, revealing an internal compensation system for maintaining IGF-1 serum concentrations. We also uncover a vital requirement of IGF-1 for perinatal viability, previously obscured by modifiers in heterogeneous genetic backgrounds.
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Affiliation(s)
- L Temmerman
- European Molecular Biology Laboratory Mouse Biology Unit, Via Ramarini 32, I-00015 Monterotondo-Scalo, Roma, Italy
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54
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Flueck M, Goldspink G. COUNTERPOINT: IGF IS NOT THE MAJOR PHYSIOLOGICAL REGULATOR OF MUSCLE MASS. J Appl Physiol (1985) 2010; 108:1821-3; discussion 1823-4; author reply 1833. [DOI: 10.1152/japplphysiol.01246.2009a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Martin Flueck
- Institute for Biomedical Research into Human Movement and Health Manchester Metropolitan University Manchester, United Kingdom
| | - Geoffrey Goldspink
- Departments of Surgery, Anatomy and Developmental Biology UCL Medical School Royal Free Campus, Hampstead, London, UK
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55
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Shavlakadze T, Chai J, Maley K, Cozens G, Grounds G, Winn N, Rosenthal N, Grounds MD. A growth stimulus is needed for IGF-1 to induce skeletal muscle hypertrophy in vivo. J Cell Sci 2010; 123:960-71. [DOI: 10.1242/jcs.061119] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Here, we characterise new strains of normal and dystrophic (mdx) mice that overexpress Class 2 IGF-1 Ea in skeletal myofibres. We show that transgenic mice have increased muscle levels of IGF-1 (~13-26 fold) and show striking muscle hypertrophy (~24-56% increase in mass). Adult normal muscles were resistant to elevated IGF-1; they reached adult steady state and maintained the same mass from 3 to 12 months. By contrast, dystrophic muscles from mdx/IGF-1(C2:Ea) mice continued to increase in mass during adulthood. IGF-1 signalling was evident only in muscles that were growing as a result of normal postnatal development (23-day-old mice) or regenerating in response to endogenous necrosis (adult mdx mice). Increased phosphorylation of Akt at Ser473 was not evident in fasted normal adult transgenic muscles, but was 1.9-fold higher in fasted normal young transgenic muscles compared with age-matched wild-type controls and fourfold higher in fasted adult mdx/IGF-1(C2:Ea) compared with mdx muscles. Muscles of adult mdx/IGF-1(C2:Ea) mice showed higher p70S6K(Thr421/Ser424) phosphorylation and both young transgenic and adult mdx/IGF-1(C2:Ea) mice had higher phosphorylation of rpS6(Ser235/236). The level of mRNA encoding myogenin was increased in normal young (but not adult) transgenic muscles, indicating enhanced myogenic differentiation. These data demonstrate that elevated IGF-1 has a hypertrophic effect on skeletal muscle only in growth situations.
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Affiliation(s)
- Thea Shavlakadze
- School of Anatomy and Human Biology, The University of Western Australia, Perth 6009, WA, Australia
| | - Jinfen Chai
- School of Anatomy and Human Biology, The University of Western Australia, Perth 6009, WA, Australia
| | - Kirsten Maley
- School of Anatomy and Human Biology, The University of Western Australia, Perth 6009, WA, Australia
| | - Greg Cozens
- School of Anatomy and Human Biology, The University of Western Australia, Perth 6009, WA, Australia
| | - Griffin Grounds
- School of Anatomy and Human Biology, The University of Western Australia, Perth 6009, WA, Australia
| | - Nadine Winn
- Mouse Biology Unit, EMBL Monterotondo Outstation, via Ramarini 32, Monterotondo, 00016 Rome, Italy
| | - Nadia Rosenthal
- Mouse Biology Unit, EMBL Monterotondo Outstation, via Ramarini 32, Monterotondo, 00016 Rome, Italy
| | - Miranda D. Grounds
- School of Anatomy and Human Biology, The University of Western Australia, Perth 6009, WA, Australia
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56
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Goldspink G, Wessner B, Tschan H, Bachl N. Growth factors, muscle function, and doping. Endocrinol Metab Clin North Am 2010; 39:169-81, xi. [PMID: 20122457 DOI: 10.1016/j.ecl.2009.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This article discusses the inevitable use of growth factors for enhancing muscle strength and athletic performance. Much effort has been expended on developing a treatment of muscle wasting associated with a range of diseases and aging. Frailty in the aging population is a major socioeconomic and medical problem. Emerging molecular techniques have made it possible to gain a better understanding of the growth factor genes and how they are activated by physical activity. The ways that misuse of growth factors may be detected and verified in athletes and future challenges for detecting manipulation of signaling pathways are discussed.
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Affiliation(s)
- Geoffrey Goldspink
- Department of Surgery, University College Medical School, University of London, London, England, UK.
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57
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Matheny RW, Nindl BC, Adamo ML. Minireview: Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration. Endocrinology 2010; 151:865-75. [PMID: 20130113 PMCID: PMC2840678 DOI: 10.1210/en.2009-1217] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The discovery that IGF-I mRNAs encoding isoforms of the pro-IGF-I molecule are differentially regulated in response to mechanical stress in skeletal muscle has been the impetus for a number of studies designed to demonstrate that alternative splicing of IGF-I pre-mRNA involving exons 4, 5, and 6 gives rise to a unique peptide derived from pro-IGF-I that plays a novel role in myoblast proliferation. Research suggests that after injury to skeletal muscle, the IGF-IEb mRNA splice variant is up-regulated initially, followed by up-regulation of the IGF-IEa splice variant at later time points. Up-regulation of IGF-IEb mRNA correlates with markers of satellite cell and myoblast proliferation, whereas up-regulation of IGF-IEa mRNA is correlated with differentiation to mature myofibers. Due to the apparent role of IGF-IEb up-regulation in muscle remodeling, IGF-IEb mRNA was also named mechano-growth factor (MGF). A synthetically manufactured peptide (also termed MGF) corresponding to the 24 most C-terminal residues of IGF-IEb has been shown to promote cellular proliferation and survival. However, no analogous peptide product of the Igf1 gene has been identified in or isolated from cultured cells, their conditioned medium, or in vivo animal tissues or biological fluids. This review will discuss the relationship of the Igf1 gene to MGF and will differentiate actions of synthetic MGF from any known product of Igf1. Additionally, the role of MGF in satellite cell activation, aging, neuroprotection, and signaling will be discussed. A survey of outstanding questions relating to MGF will also be provided.
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Affiliation(s)
- Ronald W Matheny
- U.S. Army Research Institute of Environmental Medicine, Military Performance Division, 15 Kansas Street, Building 42, Natick, Massachusetts 01760, USA.
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58
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Hewitt SC, Li Y, Li L, Korach KS. Estrogen-mediated regulation of Igf1 transcription and uterine growth involves direct binding of estrogen receptor alpha to estrogen-responsive elements. J Biol Chem 2010; 285:2676-85. [PMID: 19920132 PMCID: PMC2807324 DOI: 10.1074/jbc.m109.043471] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 11/16/2009] [Indexed: 12/20/2022] Open
Abstract
Estrogen enables uterine proliferation, which depends on synthesis of the IGF1 growth factor. This proliferation and IGF1 synthesis requires the estrogen receptor (ER), which binds directly to target DNA sequences (estrogen-responsive elements or EREs), or interacts with other transcription factors, such as AP1, to impact transcription. We observe neither uterine growth nor an increase in Igf1 transcript in a mouse with a DNA-binding mutated ER alpha (KIKO), indicating that both Igf1 regulation and uterine proliferation require the DNA binding function of the ER. We identified several potential EREs in the Igf1 gene, and chromatin immunoprecipitation analysis revealed ER alpha binding to these EREs in wild type but not KIKO chromatin. STAT5 is also reported to regulate Igf1; uterine Stat5a transcript is increased by estradiol (E(2)), but not in KIKO or alpha ERKO uteri, indicating ER alpha- and ERE-dependent regulation. ER alpha binds to a potential Stat5a ERE. We hypothesize that E(2) increases Stat5a transcript through ERE binding; that ER alpha, either alone or together with STAT5, then acts to increase Igf1 transcription; and that the resulting lack of IGF1 impairs KIKO uterine growth. Treatment with exogenous IGF1, alone or in combination with E(2), induces proliferation in wild type but not KIKO uteri, indicating that IGF1 replacement does not rescue the KIKO proliferative response. Together, these observations suggest in contrast to previous in vitro studies of IGF-1 regulation involving AP1 motifs that direct ER alpha-DNA interaction is required to increase Igf1 transcription. Additionally, full ER alpha function is needed to mediate other cellular signals of the growth factor for uterine growth.
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Affiliation(s)
- Sylvia C Hewitt
- Receptor Biology Section, Laboratory of Reproductive and Developmental Toxicology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
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59
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Zhang B, Xian C, Luo Y, Wang Y. Expression and subcellular localization of mechano-growth factor in osteoblasts under mechanical stretch. ACTA ACUST UNITED AC 2009; 52:928-34. [PMID: 19911128 DOI: 10.1007/s11427-009-0122-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 03/13/2009] [Indexed: 11/29/2022]
Abstract
Mechano-growth factor (MGF) is a stretch sensitive factor in myocytes, and it might also be produced by other mechanocytes under mechanical stimulation. In this study, both the mRNA and protein expression of MGF were detected in stretched osteoblasts. Quantitative analysis showed that a cyclic stretching stimulation caused a quick and sharp increase of MGF mRNA and protein expression from a low basal level under no stretch; the mRNA and protein levels respectively peaked in 6 and 12 h to 5 and 5.2 fold over the basal level and returned to normal by 24 h. The subcellular distribution of MGF protein was revealed by immunofluorescence analysis to be restricted to the nucleus. We concluded that cyclic stretching stimulation could induce MGF expression in osteoblasts in a pulsing fashion; and the nuclear distribution of MGF suggested that MGF might act in mechanocytes as an autocrine growth factor.
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Affiliation(s)
- BingBing Zhang
- Research Center of Bioinspired Materials Science and Engineering, Bioengineering College, Chongqing University, Chongqing, 400030, China
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60
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Quesada A, Micevych P, Handforth A. C-terminal mechano growth factor protects dopamine neurons: a novel peptide that induces heme oxygenase-1. Exp Neurol 2009; 220:255-66. [PMID: 19735655 DOI: 10.1016/j.expneurol.2009.08.029] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 08/14/2009] [Accepted: 08/22/2009] [Indexed: 12/29/2022]
Abstract
To assess potential efficacy of mechano growth factor (MGF) for chronic neurodegenerative disorders, we studied whether MGF protects dopamine (DA) neurons subjected to neurotoxic stress. We show that a short 24-amino acid C-terminal peptide of MGF (MGF24) upregulates heme oxygenase-1 (HO-1) expression and protects SH-SY5Y cells against apoptosis and cell loss induced by three DA cell-specific neurotoxins: 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenylpyridinium (MPP(+)), and rotenone. MGF24 maintains the mitochondrial membrane potential and blocks the release of mitochondrial apoptotic-inducing factor into the cytoplasm induced by 6-OHDA, MPP(+), and rotenone. Chemical inhibition of HO-1 with zinc protoporphyrin-IX prevents neuroprotection by MGF24 against the three neurotoxins. MGF24 does not activate Akt signaling nor does Akt inhibition block MGF24 protection of SH-SY5Y cells. In 6-OHDA-lesioned rats, central or peripheral MGF24 administration protects against the development of contralateral forelimb under-utilization, reduces ipsilateral nigral DA cell body loss, and attenuates tyrosine hydroxylase fiber loss in the ipsilateral striatum, independent of IGF-1 receptor activation. Peripheral MGF24 administration upregulates HO-1 expression in striatal and midbrain tissue. This report is the first to demonstrate that a small peptide, MGF24, upregulates HO-1, an important cell defense mediator, and protects DA cells, suggesting new strategies for neuroprotection in Parkinson's disease.
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Affiliation(s)
- Arnulfo Quesada
- Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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61
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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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62
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Abstract
Gene doping is the term given to the potential misuse of gene therapy for the purposes of enhancing athletic performance. Insulin like growth factor-I (IGF-I), the prime target of growth hormone action, is one candidate gene for improving performance. In recent years a number of transgenic and somatic gene transfer studies on animals have shown that upregulation of IGF-I stimulates muscle growth and improves function. This increase in muscle IGF-I is not reflected in measurable increases in circulating IGF-I. Whilst the responses obtained in the animal studies would appear to give clear benefits for performance, the transfer of such techniques to humans still presents many technical challenges. Further challenges will also be faced by the anti doping authorities in detecting the endogenously produced products of enhanced gene expression.
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Affiliation(s)
- Stephen D R Harridge
- Division of Applied Biomedical Research, School of Biomedical and Health Sciences, Shepherd's House, Guy's Campus, King's College London, London SE1 1UL, United Kingdom.
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63
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Scicchitano BM, Rizzuto E, Musarò A. Counteracting muscle wasting in aging and neuromuscular diseases: the critical role of IGF-1. Aging (Albany NY) 2009; 1:451-7. [PMID: 20157530 PMCID: PMC2806025 DOI: 10.18632/aging.100050] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 05/12/2009] [Indexed: 02/01/2023]
Abstract
Most muscle pathologies are characterized by the progressive
loss of muscle tissue due to chronic degeneration combined with
the inability of regeneration machinery to replace the damaged
muscle. These pathological changes, known as muscle wasting,
can be attributed to the activation of several proteolytic
systems, such as calpain, ubiquitin-proteasome and caspases,
and to the alteration in muscle growth factors. Among them,
insulin-like growth factor-1 (IGF-1) has been implicated in
the control of skeletal muscle growth, differentiation,
survival, and regeneration and has been considered a promising
therapeutic agent in staving off the advance of muscle weakness.
Here we review the molecular basis of muscle wasting associated
with diseases, such as sarcopenia, muscular dystrophy and
Amyotrophic Lateral Sclerosis, and discuss the potential
therapeutic role of local IGF-1 isoforms in muscle aging
and diseases.
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Affiliation(s)
- Bianca Maria Scicchitano
- Institute Pasteur Cenci-Bolognetti, Department of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome 00161, Italy
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Stavropoulou A, Halapas A, Sourla A, Philippou A, Papageorgiou E, Papalois A, Koutsilieris M. IGF-1 expression in infarcted myocardium and MGF E peptide actions in rat cardiomyocytes in vitro. Mol Med 2009; 15:127-35. [PMID: 19295919 DOI: 10.2119/molmed.2009.00012] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 03/05/2009] [Indexed: 11/06/2022] Open
Abstract
Insulinlike growth factor-1 (IGF-1) expression is implicated in myocardial pathophysiology, and two IGF-1 mRNA splice variants have been detected in rodents, IGF-1Ea and mechano-growth factor (MGF). We investigated the expression pattern of IGF-1 gene transcripts in rat myocardium from 1 h up to 8 wks after myocardial infarction induced by left anterior descending coronary artery ligation. In addition, we characterized IGF-1 and MGF E peptide action and their respective signaling in H9C2 myocardial-like cells in vitro. IGF-1Ea and MGF expression were significantly increased, both at transcriptional and translational levels, during the late postinfarction period (4 and 8 wks) in infarcted rat myocardium. Measurements of serum IGF-1 levels in infarcted rats were initially decreased (24 h up to 1 wk) but remained unaltered throughout the late experimental phase (4 to 8 wks) compared with sham-operated rats. Furthermore, specific anti-IGF-1R neutralizing antibody failed to block the synthetic MGF E peptide action, whereas it completely blocked IGF-1 action on the proliferation of H9C2 cells. Moreover, this synthetic MGF E peptide did not activate Akt phosphorylation, whereas it activated ERK1/2 in H9C2 rat myocardial cells. These data support the role of IGF-1 expression in the myocardial repair process and suggest that synthetic MGF E peptide actions may be mediated via an IGF-1R independent pathway in rat myocardial cells, as suggested by our in vitro experiments.
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Affiliation(s)
- Anastasia Stavropoulou
- Department of Experimental Physiology, Medical School, National Kapodistrian University of Athens, Goudi-Athens, Greece
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65
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Aperghis M, Velloso CP, Hameed M, Brothwood T, Bradley L, Bouloux PMG, Harridge SDR, Goldspink G. Serum IGF-I levels and IGF-I gene splicing in muscle of healthy young males receiving rhGH. Growth Horm IGF Res 2009; 19:61-67. [PMID: 18799338 DOI: 10.1016/j.ghir.2008.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 07/14/2008] [Accepted: 07/18/2008] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Elevated growth hormone (GH) levels lead to increased circulating insulin-like growth factor-I (IGF-I), but the effects on localised muscle IGF-I splice variant expression is not known. The effects of rhGH administration, with or without an acute bout of high resistance exercise, were measured on serum IGF-I and on the mRNA levels of IGF-I splice variants in the vastus lateralis muscle of healthy young men. DESIGN The study was a randomised double blind trial with a crossover design. Seven subjects were randomly assigned to a group receiving daily injections of rhGH (0.075IU kg(-1)day(-1)) or placebo for a two week period. Following a one month washout, the groups were reversed. RESULTS Administration of rhGH increased circulating IGF-I from 31.8+/-3.2 to 109+/-5.4 nmol/L (p<0.05). There was no effect of the exercise bout. RNA was extracted from muscle biopsies obtained from exercised and non-exercised legs 2.5h after the cessation of the exercise. Transcript expression was measured using Real-time QPCR. There was no effect of either exercise or rhGH administration on IGF-I 5' (Class 1 or Class 2) or 3' (IGF-IEa, or MGF) transcripts. CONCLUSION Although rhGH administration has an effect on liver IGF-I expression, as shown by increase in circulating IGF-I, muscle IGF-I expression is unaffected in young healthy subjects with normal GH profile. The findings contrast with those of a previous study in which GH deficient elderly men showed higher muscle IGF-I 3' splice variant levels following rhGH administration with and without resistance training. Unlike in the liver, muscle Class1 and 2 IGF-I expression do not change significantly following administration of rhGH.
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Affiliation(s)
- Michael Aperghis
- Department of Surgery, University College London, Hampstead Campus, London, UK
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66
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Endo T. Stem cells and plasticity of skeletal muscle cell differentiation: potential application to cell therapy for degenerative muscular diseases. Regen Med 2009; 2:243-56. [PMID: 17511561 DOI: 10.2217/17460751.2.3.243] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Degenerative muscular diseases, such as muscular dystrophies, have been the representative targets of regenerative cell therapy. Although satellite cells play central roles in skeletal muscle regeneration that intrinsically occurs after muscle injury, their application to cell therapy is confronted by difficulties. Other stem cells expected to be applicable to cell therapy include muscle-resident stem cells and nonmuscle-resident stem cells. Moreover, dedifferentiated cells of skeletal muscle might provide unique system for cell therapy. Terminally differentiated myotubes have plasticity of differentiation and dedifferentiate under certain experimental conditions, including the expression of SV40 large T antigen or the homeobox gene Msx1. The dedifferentiated cells exhibit multipotency to transdifferentiate into multiple mesenchymal origin cells. In addition, fibroblasts or undifferentiated myoblasts treated with a drug acquire multipotency. These cells may open new doors in cell therapy.
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Affiliation(s)
- Takeshi Endo
- Chiba University, Department of Biology, Graduate School of Science, Chiba 263-8522, Japan.
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67
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Semenova E, Koegel H, Hasse S, Klatte JE, Slonimsky E, Bilbao D, Paus R, Werner S, Rosenthal N. Overexpression of mIGF-1 in keratinocytes improves wound healing and accelerates hair follicle formation and cycling in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1295-310. [PMID: 18832567 DOI: 10.2353/ajpath.2008.071177] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) is an important regulator of growth, survival, and differentiation in many tissues. It is produced in several isoforms that differ in their N-terminal signal peptide and C-terminal extension peptide. The locally acting isoform of IGF-1 (mIGF-1) was previously shown to enhance the regeneration of both muscle and heart. In this study, we tested the therapeutic potential of mIGF-1 in the skin by generating a transgenic mouse model in which mIGF-1 expression is driven by the keratin 14 promoter. IGF-1 levels were unchanged in the sera of hemizygous K14/mIGF-1 transgenic animals whose growth was unaffected. A skin analysis of young animals revealed normal architecture and thickness as well as proper expression of differentiation and proliferation markers. No malignant tumors were formed. Normal homeostasis of the putative stem cell compartment was also maintained. Healing of full-thickness excisional wounds was accelerated because of increased proliferation and migration of keratinocytes, whereas inflammation, granulation tissue formation, and scarring were not obviously affected. In addition, mIGF-1 promoted late hair follicle morphogenesis and cycling. To our knowledge, this is the first work to characterize the simultaneous, stimulatory effect of IGF-1 delivery to keratinocytes on two types of regeneration processes within a single mouse model. Our analysis supports the use of mIGF-1 for skin and hair regeneration and describes a potential cell type-restricted action.
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Affiliation(s)
- Ekaterina Semenova
- European Molecular Biology Laboratory (EMBL)-Mouse Biology Unit, Campus A. Buzzati-Traverso, Monterotondo-Scalo, Roma, Italy.
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68
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Mozzetta C, Minetti G, Puri PL. Regenerative pharmacology in the treatment of genetic diseases: the paradigm of muscular dystrophy. Int J Biochem Cell Biol 2008; 41:701-10. [PMID: 18804548 DOI: 10.1016/j.biocel.2008.08.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 08/18/2008] [Accepted: 08/28/2008] [Indexed: 01/21/2023]
Abstract
Current evidence supports the therapeutic potential of pharmacological interventions that counter the progression of genetic disorders by promoting regeneration of the affected organs or tissues. The rationale behind this concept lies on the evidence that targeting key events downstream of the genetic defect can compensate, at least partially, the pathological consequence of the related disease. In this regard, the beneficial effect exerted on animal models of muscular dystrophy by pharmacological strategies that enhance muscle regeneration provides an interesting paradigm. In this review, we describe and discuss the potential targets of pharmacological strategies that promote regeneration of dystrophic muscles and alleviate the consequence of the primary genetic defect. Regenerative pharmacology provides an immediate and suitable therapeutic opportunity to slow down the decline of muscles in the present generation of dystrophic patients, with the perspective to hold them in conditions such that they could benefit of future, more definitive, therapies.
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Affiliation(s)
- Chiara Mozzetta
- Dulbecco Telethon Institute at Fondazione Santa Lucia/EBRI, Via di Fosso Fiorano, 64-00143 Roma, Italy
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69
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Ridgley JA, Pinniger GJ, Hamer PW, Grounds MD. The physiological effects of IGF-1 (class 1:Ea transgene) over-expression on exercise-induced damage and adaptation in dystrophic muscles of mdx mice. Pflugers Arch 2008; 457:1121-32. [DOI: 10.1007/s00424-008-0568-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 07/24/2008] [Accepted: 07/29/2008] [Indexed: 10/21/2022]
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70
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Wu Z, Sofronic-Milosavljevic L, Nagano I, Takahashi Y. Trichinella spiralis: nurse cell formation with emphasis on analogy to muscle cell repair. Parasit Vectors 2008; 1:27. [PMID: 18710582 PMCID: PMC2538513 DOI: 10.1186/1756-3305-1-27] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 08/19/2008] [Indexed: 12/18/2022] Open
Abstract
Trichinella infection results in formation of a capsule in infected muscles. The capsule is a residence of the parasite which is composed of the nurse cell and fibrous wall. The process of nurse cell formation is complex and includes infected muscle cell response (de-differentiation, cell cycle re-entry and arrest) and satellite cell responses (activation, proliferation and differentiation). Some events that occur during the nurse cell formation are analogous to those occurring during muscle cell regeneration/repair. This article reviews capsule formation with emphasis on this analogy.
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Affiliation(s)
- Zhiliang Wu
- Department of Parasitology, Gifu University Graduate School of Medicine, Yanagido 1-1, Gifu, 501-1194, Japan.
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71
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Abstract
Growth hormone (GH) is widely used as a performance-enhancing drug. One of its best-characterized effects is increasing levels of circulating insulin-like growth factor I (IGF-I), which is primarily of hepatic origin. It also induces synthesis of IGF-I in most non-hepatic tissues. The effects of GH in promoting postnatal body growth are IGF-I dependent, but IGF-I-independent functions are beginning to be elucidated. Although benefits of GH administration have been reported for those who suffer from GH deficiency, there is currently very little evidence to support an anabolic role for supraphysiological levels of systemic GH or IGF-I in skeletal muscle of healthy individuals. There may be other performance-enhancing effects of GH. In contrast, the hypertrophic effects of muscle-specific IGF-I infusion are well documented in animal models and muscle cell culture systems. Studies examining the molecular responses to hypertrophic stimuli in animals and humans frequently cite upregulation of IGF-I messenger RNA or immunoreactivity. The circulatory/systemic (endocrine) and local (autocrine/paracrine) effects of GH and IGF-I may have distinct effects on muscle mass regulation.
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72
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Grounds MD, Radley HG, Gebski BL, Bogoyevitch MA, Shavlakadze T. IMPLICATIONS OF CROSS-TALK BETWEEN TUMOUR NECROSIS FACTOR AND INSULIN-LIKE GROWTH FACTOR-1 SIGNALLING IN SKELETAL MUSCLE. Clin Exp Pharmacol Physiol 2008; 35:846-51. [DOI: 10.1111/j.1440-1681.2007.04868.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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73
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Scrable H, Medrano S, Ungewitter E. Running on empty: how p53 controls INS/IGF signaling and affects life span. Exp Gerontol 2008; 44:93-100. [PMID: 18598747 DOI: 10.1016/j.exger.2008.05.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 05/21/2008] [Accepted: 05/27/2008] [Indexed: 10/21/2022]
Abstract
In higher organisms dependent on the regenerative ability of tissue stem cells to maintain tissue integrity throughout adulthood, the failure of stem cells to replace worn out, dead, or damaged cells is seen as one mechanism that limits life span. In these organisms, tumor suppressors such as p53 are central participants in the control of longevity because they regulate stem cell proliferation. Several recent reports have identified p53 as a longevity gene in organisms such as Caenorhabditis elegans and Drosophila melanogaster, which lack proliferative stem cells in all but the germline and have relatively short life spans. This has forced us to reevaluate the role of p53 in the control of life span. We discuss how p53 might regulate longevity in both long- and short-lived species by controlling the activity of insulin-like molecules that operate in proliferating and non-proliferating compartments of adult somatic tissues. We also discuss the hierarchical structure of life span regulation where loss of p53 has life span extending effects. Finally, we suggest a molecular mechanism by which p53 might facilitate the response to severe nutrient deprivation that allows metabolically active cells to survive periods of starvation. Paradoxically, loss of p53 function in these cells would compromise life span.
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Affiliation(s)
- Heidi Scrable
- University of Virginia, Department of Neuroscience, Charlottesville, Virginia, USA.
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74
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Tokunou T, Miller R, Patwari P, Davis ME, Segers VFM, Grodzinsky AJ, Lee RT. Engineering insulin-like growth factor-1 for local delivery. FASEB J 2008; 22:1886-93. [PMID: 18285400 DOI: 10.1096/fj.07-100925] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Insulin-like growth factor-1 (IGF-1) is a small protein that promotes cell survival and growth, often acting over long distances. Although for decades IGF-1 has been considered to have therapeutic potential, systemic side effects of IGF-1 are significant, and local delivery of IGF-1 for tissue repair has been a long-standing challenge. In this study, we designed and purified a novel protein, heparin-binding IGF-1 (Xp-HB-IGF-1), which is a fusion protein of native IGF-1 with the heparin-binding domain of heparin-binding epidermal growth factor-like growth factor. Xp-HB-IGF-1 bound selectively to heparin as well as the cell surfaces of 3T3 fibroblasts, neonatal cardiac myocytes and differentiating ES cells. Xp-HB-IGF-1 activated the IGF-1 receptor and Akt with identical kinetics and dose response, indicating no compromise of biological activity due to the heparin-binding domain. Because cartilage is a proteoglycan-rich environment and IGF-1 is a known stimulus for chondrocyte biosynthesis, we then studied the effectiveness of Xp-HB-IGF-1 in cartilage. Xp-HB-IGF-1 was selectively retained by cartilage explants and led to sustained chondrocyte proteoglycan biosynthesis compared to IGF-1. These data show that the strategy of engineering a "long-distance" growth factor like IGF-1 for local delivery may be useful for tissue repair and minimizing systemic effects.
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Affiliation(s)
- Tomotake Tokunou
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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75
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Rehage M, Mohan S, Wergedal JE, Bonafede B, Tran K, Hou D, Phang D, Kumar A, Qin X. Transgenic overexpression of pregnancy-associated plasma protein-A increases the somatic growth and skeletal muscle mass in mice. Endocrinology 2007; 148:6176-85. [PMID: 17901236 DOI: 10.1210/en.2007-0274] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although IGFs are indispensable to skeletal muscle development, little information is available regarding the mechanisms regulating the local action of IGFs in skeletal muscle tissues. Here we tested the hypothesis that pregnancy-associated plasma protein-A (PAPP-A), a member of the metalloproteinase superfamily, promotes skeletal muscle formation in vivo through degrading IGF binding proteins (IGFBPs), which increases the bioavailability of IGFs. Expression of PAPP-A is significantly increased in muscle five days after muscle injury in mice. Targeted overexpression of PAPP-A using a muscle-specific promoter significantly increased the prenatal/postnatal growth, skeletal muscle weight, and muscle fiber area in mice. These anabolic effects were reproduced using F2/F3 progeny. Free IGF-I concentration was severalfold higher in the conditioned medium (CM) of ex vivo cultured muscle from the transgenic mice, compared with the wild-type littermate muscle. Accordingly, the proliferation of C2C12 myoblasts was significantly increased in the presence of CM from cultured skeletal muscle of the transgenic mice, compared with the controls. This observed increase in myoblast proliferation was abolished on addition of noncleavable IGFBP-4 peptide, which reduced free IGF-I concentration back to the basal level of the wild-type CM. Furthermore, proliferation and differentiation of C2C12 myoblasts was increased by transient overexpression of proteolytically active PAPP-A but not by inactive mutant PAPP-A (E483/A). Collectively, we identified PAPP-A as a novel regulator of prenatal/postnatal growth and skeletal muscle formation in vivo. Moreover, our studies provide the first experimental evidence that IGFBP degradation is a key determinant in modulating the local action of IGFs in muscle.
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Affiliation(s)
- Mark Rehage
- Musculoskeletal Disease Center, J. L. Pettis Veterans Affairs Medical Center (151), 11201 Benton Street, Loma Linda, CA 92357, USA
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76
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Górecki DC, Beresewicz M, Zabłocka B. Neuroprotective effects of short peptides derived from the Insulin-like growth factor 1. Neurochem Int 2007; 51:451-8. [PMID: 17582656 DOI: 10.1016/j.neuint.2007.04.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 04/03/2007] [Accepted: 04/25/2007] [Indexed: 11/22/2022]
Abstract
Insulin-like growth factor I (IGF-1) is a peptide synthesized in response to growth hormone stimulation. While most of the circulating IGF-1 comes from the liver, it can also be produced in other tissues and both its expression and processing undergo tissue-specific regulation. The predominant form, IGF-1Ea is a circulating factor while two others, IGF-1Eb and IGF-1Ec (MGF), are mostly expressed in different tissues or in response to various stimuli and show some preferences with respect to the signal transduction pathways they activate. In skeletal muscle specific forms of IGF-1 play a role in development and growth and in addition to these physiological roles IGF-1 functions in the damaged muscle. IGF-1 is also important for the developing and adult brain and can reduce neuronal death caused by different types of injuries. Like many other peptide hormones IGF-1 originates from a precursor pro-hormone that undergoes extensive post-translational modifications. Processing liberates the mature peptide, which acts via the specific IGF-1 receptor but additional short peptides can arise from both N- and C-termini of various IGF-1 isoforms. These derivatives function as autonomous biologically active peptides and extremely potent neuroprotective agents. Their biological effects are independent of the activation of the IGF-1 receptor. Unfortunately, little is known about their mechanism(s) of action. Likewise, the existence of the endogenous production and wider biological effects of these short peptides are uncertain. However, considering the difference in the modes of action it might be possible to dissociate the unwanted and potentially dangerous mitogenic activity of the full-length IGF-1 exerted via its receptor from the neuroprotective effects of short derivatives mediated through different pathways. Such small molecules show good penetration through the blood brain barrier, can be inexpensively manufactured and modified to increase their stability. Therefore, they are good candidates for development into a neuroprotective therapeutic modality.
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Affiliation(s)
- Dariusz C Górecki
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, Portsmouth, England, United Kingdom
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77
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Schertzer JD, Gehrig SM, Ryall JG, Lynch GS. Modulation of insulin-like growth factor (IGF)-I and IGF-binding protein interactions enhances skeletal muscle regeneration and ameliorates the dystrophic pathology in mdx mice. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1180-8. [PMID: 17823291 PMCID: PMC1988868 DOI: 10.2353/ajpath.2007.070292] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Administration of recombinant human insulin-like growth factor-I (rhIGF-I) has beneficial effects in animal models of muscle injury and muscular dystrophy. However, the results of these studies may have been confounded by interactions of rhIGF-I with endogenous IGF-binding proteins (IGFBPs). To date, no study has examined whether inhibiting IGFBP interactions with endogenous IGF-I can improve muscle fiber regeneration or muscular pathologies. We tested the hypothesis that reducing IGFBP interactions with endogenous IGF-I would enhance muscle regeneration after myotoxic injury and improve the dystrophic pathology in mdx mice. We administered an IGF-I aptamer (NBI-31772; 6 mg/kg per day, continuous infusion) to C57BL/10 mice undergoing regeneration after myotoxic injury or to mdx dystrophic mice. NBI-31772 binds all six IGFBPs with high affinity and releases "free" endogenous IGF-I. NBI-31772 treatment increased the rate of functional repair in fast-twitch tibialis anterior muscles after notexin-induced injury as evidenced by an increase in maximum force producing capacity (P(o)) at 10 days after injury. In contrast, NBI-31772 administration for 28 days did not alter P(o) of extensor digitorum longus (EDL) and soleus muscles or normalized force of diaphragm muscle strips from mdx mice. Although IGFBP inhibition reduced the susceptibility of the fast-twitch EDL and the diaphragm muscle to contraction-mediated damage, it increased muscle fatigability during repeated maximal contractions. Although the results in the myotoxic injury model suggest IGF-I signaling is important in this model, the results in the mdx model are mixed.
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Affiliation(s)
- Jonathan D Schertzer
- Department of Physiology, The University of Melbourne, Melbourne, VIC, 3010, Australia.
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78
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Abstract
Human skeletal muscle is a highly heterogeneous tissue, able to adapt to the different challenges that may be placed upon it. When overloaded, a muscle adapts by increasing its size and strength through satellite-cell-mediated mechanisms, whereby protein synthesis is increased and new nuclei are added to maintain the myonuclear domain. This process is regulated by an array of mechanical, hormonal and nutritional signals. Growth factors, such as insulin-like growth factor I (IGF-I) and testosterone, are potent anabolic agents, whilst myostatin acts as a negative regulator of muscle mass. Insulin-like growth factor I is unique in being able to stimulate both the proliferation and the differentiation of satellite cells and works as part of an important local repair and adaptive mechanism. Speed of movement, as characterized by maximal velocity of shortening (V(max)), is regulated primarily by the isoform of myosin heavy chain (MHC) contained within a muscle fibre. Human fibres can express three MHCs: MHC-I, -IIa and -IIx, in order of increasing V(max) and maximal power output. Training studies suggest that there is a subtle interplay between the MHC-IIa and -IIx isoforms, with the latter being downregulated by activity and upregulated by inactivity. However, switching between the two main isoforms appears to require significant challenges to a muscle. Upregulation of fast gene programs is caused by prolonged disuse, whilst upregulation of slow gene programs appears to require significant and prolonged activity. The potential mechanisms by which alterations in muscle composition are mediated are discussed. The implications in terms of contractile function of altering muscle phenotype are discussed from the single fibre to the whole muscle level.
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Affiliation(s)
- Stephen D R Harridge
- Division of Applied Biomedical Research, School of Biomedical & Health Sciences, King's College London, 4.14 Shepherd's House, Guy's Campus, London SE1 1UL, UK.
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79
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Alfieri CM, Evans-Anderson HJ, Yutzey KE. Developmental regulation of the mouse IGF-I exon 1 promoter region by calcineurin activation of NFAT in skeletal muscle. Am J Physiol Cell Physiol 2007; 292:C1887-94. [PMID: 17229811 DOI: 10.1152/ajpcell.00506.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Skeletal muscle development and growth are regulated through multiple signaling pathways that include insulin-like growth factor I (IGF-I) and calcineurin activation of nuclear factor of activated T cell (NFAT) transcription factors. The developmental regulation and molecular mechanisms that control IGF-I gene expression in murine embryos and in differentiating C2C12 skeletal myocytes were examined. IGF-I is expressed in developing skeletal muscle, and its embryonic expression is significantly reduced in embryos lacking both NFATc3 and NFATc4. During development, the IGF-I exon 1 promoter is active in multiple organ systems, including skeletal muscle, whereas the alternative exon 2 promoter is expressed predominantly in the liver. The IGF-I exon 1 promoter flanking sequence includes two highly conserved regions that contain NFAT consensus binding sequences. One of these conserved regions contains a calcineurin/NFAT-responsive regulatory region that is preferentially activated by NFATc3 in C2C12 skeletal muscle cells and NIH3T3 fibroblasts. This NFAT-responsive region contains three clustered NFAT consensus binding sequences, and mutagenesis experiments demonstrated the requirement for two of these in calcineurin or NFATc3 responsiveness. Chromatin immunoprecipitation analyses demonstrated that endogenous IGF-I genomic sequences containing these conserved NFAT binding sequences interact preferentially with NFATc3 in C2C12 cells. Together, these experiments demonstrated that a NFAT-rich regulatory element in the IGF-I exon 1 promoter flanking region is responsive to calcineurin signaling and NFAT activation in skeletal muscle cells. The identification of a calcineurin/NFAT-responsive element in the IGF-I gene represents a potential mechanism of intersection of these signaling pathways in the control of muscle development and homeostasis.
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Affiliation(s)
- Christina M Alfieri
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Medical Center, ML 7020, 3333 Burnet Ave., Cincinnati, OH 45229, USA
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80
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Mills P, Lafrenière JF, Benabdallah BF, El Fahime EM, Tremblay JP. A new pro-migratory activity on human myogenic precursor cells for a synthetic peptide within the E domain of the mechano growth factor. Exp Cell Res 2007; 313:527-37. [PMID: 17156777 DOI: 10.1016/j.yexcr.2006.10.032] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 10/30/2006] [Accepted: 10/30/2006] [Indexed: 10/23/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an inherited disease that leads to progressive muscle wasting. Myogenic precursor cell transplantation is an approach that can introduce the normal dystrophin gene in the muscle fibers of the patients. Unfortunately, these myogenic precursor cells do not migrate well in the muscle and thus many injections have to be done to enable a good graft success. Recent reports have shown that there is extensive splicing of the IGF-1 gene in muscles. The MGF isoform contains a C-terminal 24 amino acids peptide in the E domain (MGF-Ct24E) that has intrinsic properties. It can promote the proliferation while delaying the differentiation of C(2)C(12) cells. Here, we demonstrated that this synthetic peptide is a motogenic factor for human precursor myogenic cells in vitro and in vivo. Indeed, MGF-Ct24E peptide can modulate members of the fibrinolytic and metalloproteinase systems, which are implicated in the migration of myogenic cells. MGF-Ct24E peptide enhances the expression of u-PA, u-PAR and MMP-7 while reducing PAI-1 activity. Moreover, it has no effect on the gelatinases MMP-2 and -9. Those combined effects can favour cell migration. Finally, we present some results suggesting that the MGF-Ct24E peptide induces these cell responses through a mechanism that does not involve the IGF-1 receptor. Thus, this MGF-Ct24E peptide has a new pro-migratory activity on human myogenic precursor cells that may be helpful in the treatment of DMD. Those results reinforce the possibility that the IGF-1Ec isoform may produce an E domain peptide that can act as a cytokine.
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Affiliation(s)
- Philippe Mills
- Unité de recherche en génétique humaine, CHUQ-CHUL, 2705 boul. Laurier, Ste-Foy, Qc, Canada G1V 4G2
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81
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Heydemann A, Doherty KR, McNally EM. Genetic modifiers of muscular dystrophy: Implications for therapy. Biochim Biophys Acta Mol Basis Dis 2007; 1772:216-28. [PMID: 16916601 DOI: 10.1016/j.bbadis.2006.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 06/22/2006] [Indexed: 10/24/2022]
Abstract
The genetic understanding of the muscular dystrophies has advanced considerably in the last two decades. Over 25 different individual genes are now known to produce muscular dystrophy, and many different "private" mutations have been described for each individual muscular dystrophy gene. For the more common forms of muscular dystrophy, phenotypic variability can be explained by precise mutations. However, for many genetic mutations, the presence of the identical mutation is associated with marked phenotypic range that affects muscle function as well as cardiac function. The explanation for phenotype variability in the muscular dystrophies is only now being explored. The availability of genetically engineered animal models has allowed the generation of single mutations on the background of highly inbred strain. Phenotypic variation that is altered by genetic background argues for the presence of genetic modifier loci that can ameliorate or enhance aspects of the dystrophic phenotype. A number of individual genes have been implicated as modifiers of muscular dystrophy by studies in genetically engineered mouse models of muscular dystrophy. The value of these genes and products is that the pathways identified through these experiments may be exploited for therapy.
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Affiliation(s)
- Ahlke Heydemann
- Department of Medicine, Section of Cardiology, The University of Chicago, Chicago, IL 60637, USA
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82
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Abstract
Skeletal muscle size is dynamic and responsive to extracellular signals such as mechanical load, neural activity, hormones, growth factors, and cytokines. The signaling pathways responsible for regulating cell size in adult skeletal muscle under growth and atrophy conditions are poorly understood. However, recent evidence suggests a role for the PI3K/Akt/mTOR pathway. Protein translation is regulated through the phosphorylation of initiation factors that are controlled by signaling pathways downstream of PI3K/Akt. Recent work in mammals has suggested that activation of Akt/PKB, a Ser-Thr phosphatidylinositol-regulated kinase, and its downstream targets, glycogen synthase kinase-3 (GSK3) and the mammalian target of rapamycin (mTOR), may be critical regulators of postnatal cell size in multiple organ systems, including skeletal muscle. This paper will review some of the recent data that demonstrate the critical role of Akt/mTOR signaling in the regulation of postnatal muscle size, especially under conditions of increased external loading.
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Affiliation(s)
- Sue C Bodine
- Section of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA 95616, USA.
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83
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Foster K, Foster H, Dickson JG. Gene therapy progress and prospects: Duchenne muscular dystrophy. Gene Ther 2006; 13:1677-85. [PMID: 17066097 DOI: 10.1038/sj.gt.3302877] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder affecting 1/3500 male births. There is currently no effective treatment, but gene therapy approaches are offering viable avenues for treatment development. The last 10 years have seen the development of a number of strategies and tools for muscle gene therapy. However, the major hurdle has been the inability to deliver vectors at high enough efficiency via a systemic route. The last 2-3 years (reviewed here) have seen unrivalled progress in efficient systemic delivery of viral and non-viral gene transfer agents and antisense oligonucleotides. This progress, coupled with the successful completion of the first gene therapy clinical trial for DMD, has led to three more clinical trials planned for the immediate future.
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Affiliation(s)
- K Foster
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
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84
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Charvet C, Houbron C, Parlakian A, Giordani J, Lahoute C, Bertrand A, Sotiropoulos A, Renou L, Schmitt A, Melki J, Li Z, Daegelen D, Tuil D. New role for serum response factor in postnatal skeletal muscle growth and regeneration via the interleukin 4 and insulin-like growth factor 1 pathways. Mol Cell Biol 2006; 26:6664-74. [PMID: 16914747 PMCID: PMC1592825 DOI: 10.1128/mcb.00138-06] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Serum response factor (SRF) is a crucial transcriptional factor for muscle-specific gene expression. We investigated SRF function in adult skeletal muscles, using mice with a postmitotic myofiber-targeted disruption of the SRF gene. Mutant mice displayed severe skeletal muscle mass reductions due to a postnatal muscle growth defect resulting in highly hypotrophic adult myofibers. SRF-depleted myofibers also failed to regenerate following injury. Muscles lacking SRF had very low levels of muscle creatine kinase and skeletal alpha-actin (SKA) transcripts and displayed other alterations to the gene expression program, indicating an overall immaturity of mutant muscles. This loss of SKA expression, together with a decrease in beta-tropomyosin expression, contributed to myofiber growth defects, as suggested by the extensive sarcomere disorganization found in mutant muscles. However, we observed a downregulation of interleukin 4 (IL-4) and insulin-like growth factor 1 (IGF-1) expression in mutant myofibers which could also account for their defective growth and regeneration. Indeed, our demonstration of SRF binding to interleukin 4 and IGF-1 promoters in vivo suggests a new crucial role for SRF in pathways involved in muscle growth and regeneration.
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MESH Headings
- Animals
- Animals, Newborn
- Base Sequence
- Cell Nucleus/metabolism
- Cell Size
- Gene Expression Regulation
- Insulin-Like Growth Factor I/genetics
- Insulin-Like Growth Factor I/metabolism
- Integrases/genetics
- Interleukin-4/genetics
- Interleukin-4/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Sequence Data
- Muscle, Skeletal/cytology
- Muscle, Skeletal/growth & development
- Muscle, Skeletal/physiology
- Muscle, Skeletal/ultrastructure
- Organ Size
- Phenotype
- Promoter Regions, Genetic/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Regeneration
- Sarcomeres/pathology
- Sarcomeres/ultrastructure
- Serum Response Factor/deficiency
- Serum Response Factor/genetics
- Serum Response Factor/metabolism
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Affiliation(s)
- Claude Charvet
- Institut Cochin, Faculté de Médecine Cochin Port Royal, 24 rue du Faubourg Saint Jacques, 75014 Paris, France
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85
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Costelli P, Muscaritoli M, Bossola M, Penna F, Reffo P, Bonetto A, Busquets S, Bonelli G, Lopez-Soriano FJ, Doglietto GB, Argilés JM, Baccino FM, Rossi Fanelli F. IGF-1 is downregulated in experimental cancer cachexia. Am J Physiol Regul Integr Comp Physiol 2006; 291:R674-83. [PMID: 16614058 DOI: 10.1152/ajpregu.00104.2006] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cancer cachexia is characterized by skeletal muscle wasting that is mainly supported by hypercatabolism. Muscle atrophy has been suggested to depend on impaired IGF-1 signal transduction pathway. The present study has been aimed at investigating the IGF-1 system in rats bearing the AH-130 hepatoma, a well-characterized model of cachexia. IGF-1 mRNA expression in the gastrocnemius of tumor hosts progressively decreases to ∼50% of controls. By contrast, both IGF-1 receptor and insulin receptor mRNA levels increase in day 7 AH-130 hosts. IGF-1 and insulin circulating levels, as well as IGF-1 expression in the liver, are reduced. Muscle wasting in the AH-130 bearers is associated with hyperactivation of the ubiquitin-proteasome system. Consistently, the mRNA levels of ubiquitin and of the ubiquitin ligases atrogin-1 and MuRF1 are significantly increased in the gastrocnemius of day 7 AH-130 hosts. Exogenous IGF-1 administered to tumor bearers does not prevent cachexia. IGF-1 mRNA levels also have been evaluated in the gastrocnemius of AH-130 hosts treated with pentoxifylline, an inhibitor of TNF-α synthesis, alone or combined with formoterol, a β2-adrenergic agonist. Both treatments partially correct muscle atrophy without modifying IGF-1 and atrogin-1 mRNA levels, whereas MuRF1 hyperexpression is reduced by the combination of pentoxifylline with formoterol. These results demonstrate for the first time that the IGF-1 system is downregulated in cancer cachexia, although the underlying mechanism remains unknown. Moreover, no simple relation linking IGF-1 and/or atrogin-1 mRNA levels and muscle atrophy could be observed in these experimental conditions. Further studies are thus needed to clarify both issues.
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Affiliation(s)
- Paola Costelli
- Dipartimento di Medicina e Oncologia Sperimentale, Università di Torino, Turin, Italy.
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86
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Schertzer JD, Lynch GS. Comparative evaluation of IGF-I gene transfer and IGF-I protein administration for enhancing skeletal muscle regeneration after injury. Gene Ther 2006; 13:1657-64. [PMID: 16871234 DOI: 10.1038/sj.gt.3302817] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Developing methodologies to enhance skeletal muscle regeneration and hasten the restoration of muscle function has important implications for minimizing disability after injury and for treating muscle diseases such as Duchenne muscular dystrophy. Although delivery of various growth factors, such as insulin-like growth factor-I (IGF-I), have proved successful in promoting skeletal muscle regeneration after injury, no study has compared the efficacy of different delivery methods directly. We compared the efficacy of systemic delivery of recombinant IGF-I protein via mini-osmotic pump (approximately 1.5 mg/kg/day) with a single electrotransfer-assisted plasmid-based gene transfer, to hasten functional repair of mouse tibialis anterior muscles after myotoxic injury. The relative efficacy of each method was assessed at 7, 21 and 28 days post-injury. Our findings indicate that IGF-I hastened functional recovery, regardless of the route of IGF-I administration. However, gene transfer of IGF-I was superior to systemic protein administration because in the regenerating muscle, this delivery method increased IGF-I levels, activated intracellular signals (Akt phosphorylation), induced a greater magnitude of myofiber hypertrophy and hastened functional recovery at an earlier time point (14 days) after injury than did protein administration (21 days). Thus, the relative efficacy of different modes of delivery is an important consideration when assessing the therapeutic potential of various proteins for treating muscle injuries and skeletal muscle diseases.
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Affiliation(s)
- J D Schertzer
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Grattan Street, Victoria 3010, Australia
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87
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Musarò A, Dobrowolny G, Rosenthal N. The neuroprotective effects of a locally acting IGF-1 isoform. Exp Gerontol 2006; 42:76-80. [PMID: 16782294 DOI: 10.1016/j.exger.2006.05.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Revised: 05/02/2006] [Accepted: 05/03/2006] [Indexed: 01/20/2023]
Abstract
In the last decade, dramatic progress has been made in elucidating the molecular defects underlying a number of neuromuscular diseases. With the characterization of mutations responsible for muscle and nerve dysfunction in several inherited pathologies, and the identification of novel signaling pathways, in which subtle alterations can lead to significant defects in tissue metabolism, the field is poised to devise successful strategies for treatment of this debilitating and often fatal group of human ailments. Yet progress in therapeutic application has been slow despite our newly gained knowledge of basic biology. Hence, where direct therapeutic approaches to address the primary diseases are still sub-optimal, it may be more effective to focus on strategies for improving neuromuscular function. Among potential candidates, insulin-like growth factor (IGF-1) has been involved in several anabolic pathways in both skeletal muscle and the nervous system and it is a promising candidate to attenuate neuromuscular diseases. In this review, we will discuss the role of IGF-1 isoforms in neuromuscular diseases and the contribution of muscle-produced IGF-1 (mIGF-1) to motor neuron survival and activity.
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Affiliation(s)
- Antonio Musarò
- Department of Histology and Medical Embryology, CE-BEMM and Interuniversity Institute of Myology, University of Rome La Sapienza, Italy.
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88
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Shavlakadze T, Boswell JM, Burt DW, Asante EA, Tomas FM, Davies MJ, White JD, Grounds MD, Goddard C. Rskalpha-actin/hIGF-1 transgenic mice with increased IGF-I in skeletal muscle and blood: impact on regeneration, denervation and muscular dystrophy. Growth Horm IGF Res 2006; 16:157-173. [PMID: 16716629 DOI: 10.1016/j.ghir.2005.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 11/08/2005] [Accepted: 11/09/2005] [Indexed: 10/24/2022]
Abstract
Human IGF-I was over-expressed in skeletal muscles of C57/BL6xCBA mice under the control of the rat skeletal alpha-actin gene promoter. RT-PCR verified expression of the transgene in skeletal muscle but not in the liver of 1- and 21-day old heterozygote transgenic mice. The concentration of endogenous mouse IGF-I, measured by an immunoassay which does not detect human IGF-I, was not significantly different between transgenic mice and wild-type littermates (9.5 +/- 0.8 and 13.3 +/- 1.9 ng/g in muscle; 158.3 +/- 18.6 and 132.9 +/- 33.1 ng/ml in plasma, respectively). In contrast, quantitation with antibodies to human IGF-I showed an increase in IGF-I of about 100 ng/ml in plasma and 150 ng/g in muscle of transgenic mice at 6 months of age. Transgenic males, compared to their age matched wild-type littermates, had a significantly higher body weight (38.6 +/- 0.53 g vs. 35.8 +/- 0.64 g at 6 months of age; P < 0.001), dry fat-free carcass mass (5.51 +/- 0.085 vs. 5.08 +/- 0.092 g; P < 0.001) and myofibrillar protein mass (1.62 +/- 0.045 vs. 1.49 +/- 0.048 g; P < 0.05), although the fractional content of fat in the carcass was lower (167 +/- 7.0 vs. 197 +/- 7.7 g/kg wet weight) in transgenic animals. There was no evidence of muscle hypertrophy and no change in the proportion of slow type I myofibres in the limb muscles of Rskalpha-actin/hIGF-I transgenic mice at 3 or 6 months of age. Phenotypic changes in Rskalpha-actin/hIGF-I mice are likely to be due to systemic as well as autocrine/paracrine effects of overproduction of IGF-I due to expression of the human IGF-I transgene. The effect of muscle specific over-expression of Rskalpha-actin/hIGF-I transgene was tested on: (i) muscle regeneration in auto-transplanted whole muscle grafts; (ii) myofibre atrophy following sciatic nerve transection; and (iii) sarolemmal damage and myofibre necrosis in dystrophic mdx muscle. No beneficial effect of muscle specific over-expression of Rskalpha-actin/hIGF-I transgene was seen in these three experimental models.
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Affiliation(s)
- T Shavlakadze
- School of Anatomy and Human Biology, The University of Western Australia, Crawley, Perth.
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89
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Sotiropoulos A, Ohanna M, Kedzia C, Menon RK, Kopchick JJ, Kelly PA, Pende M. Growth hormone promotes skeletal muscle cell fusion independent of insulin-like growth factor 1 up-regulation. Proc Natl Acad Sci U S A 2006; 103:7315-20. [PMID: 16670201 PMCID: PMC1456062 DOI: 10.1073/pnas.0510033103] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Growth hormone (GH) participates in the postnatal regulation of skeletal muscle growth, although the mechanism of action is unclear. Here we show that the mass of skeletal muscles lacking GH receptors is reduced because of a decrease in myofiber size with normal myofiber number. GH signaling controls the size of the differentiated myotubes in a cell-autonomous manner while having no effect on size, proliferation, and differentiation of the myoblast precursor cells. The GH hypertrophic action leads to an increased myonuclear number, indicating that GH facilitates fusion of myoblasts with nascent myotubes. NFATc2, a transcription factor regulating this phase of fusion, is required for GH action because GH is unable to induce hypertrophy of NFATc2-/- myotubes. Finally, we provide three lines of evidence suggesting that GH facilitates cell fusion independent of insulin-like growth factor 1 (IGF-1) up-regulation. First, GH does not regulate IGF-1 expression in myotubes; second, GH action is not mediated by a secreted factor in conditioned medium; third, GH and IGF-1 hypertrophic effects are additive and rely on different signaling pathways. Taken together, these data unravel a specific function of GH in the control of cell fusion, an essential process for muscle growth.
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Affiliation(s)
- Athanassia Sotiropoulos
- Institut National de la Santé et de la Recherche Médicale, U810, and Faculté de Médecine Necker-Enfants Malades, Université Paris 5, F-75730 Paris, France.
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90
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Abstract
Mechanical force is generated within skeletal muscle cells by contraction of specialized myofibrillar proteins. This paper explores how the contractile force generated at the sarcomeres within an individual muscle fiber is transferred through the connective tissue to move the bones. The initial key point for transfer of the contractile force is the muscle cell membrane (sarcolemma) where force is transferred laterally to the basement membrane (specialized extracellular matrix rich in laminins) to be integrated within the connective tissue (rich in collagens) before transmission to the tendons. Connections between (1) key molecules outside the myofiber in the basement membrane to (2) molecules within the sarcolemma of the myofiber and (3) the internal cytoplasmic structures of the cytoskeleton and sarcomeres are evaluated. Disturbances to many components of this complex interactive system adversely affect skeletal muscle strength and integrity, and can result in severe muscle diseases. The mechanical aspects of these crucial linkages are discussed, with particular reference to defects in laminin-alpha2 and integrin-alpha7. Novel interventions to potentially increase muscle strength and reduce myofiber damage are mentioned, and these are also highly relevant to muscle diseases and aging muscle.
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Affiliation(s)
- M D Grounds
- School of Anatomy and Human Biology, The University of Western Australia, Perth, WA, Australia.
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91
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Patruno M, Maccatrozzo L, Funkenstein B, Radaelli G. Cloning and expression of insulin-like growth factors I and II in the shi drum (Umbrina cirrosa). Comp Biochem Physiol B Biochem Mol Biol 2006; 144:137-51. [PMID: 16644254 DOI: 10.1016/j.cbpb.2006.02.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 01/25/2006] [Accepted: 02/03/2006] [Indexed: 12/11/2022]
Abstract
Insulin-like growth factors (IGFs) are evolutionarily ancient polypeptides, with potent metabolic actions, affecting cell development and growth. The IGF system consists of two ligands: IGF-I and IGF-II, several binding proteins and high-affinity transmembrane receptors. To understand growth regulation in the teleost shi drum, Umbrina cirrosa, we cloned IGF-I and IGF-II cDNAs, studied their expression and determined the cellular localization of IGF-II peptide by immunohistochemistry. A fragment of 1110 nucleotides, coding for U. cirrosa IGF-I (ucIGF-I), was cloned from liver by PCR. It includes an open reading frame of 561 nucleotides, encoding a 187 amino acid preproIGF-I. A fragment of 938 nucleotides that includes part of the coding sequence and the 3' UTR of IGF-II (ucIGF-II) was cloned as well. Sequence analysis of ucIGF-I and ucIGF-II showed a high degree of homology with known fish IGF-I and IGF-II. Real-Time PCR showed a higher expression of IGF-I and IGF-II in liver, compared to all other tissues analysed. IGF-II peptide was detected in larval liver, intestine, gills and heart musculature. After metamorphosis, reactivity was particularly evident in the kidney and in red fibres of skeletal muscle. These results add novel information on the nucleotide sequence of IGF-I and IGF-II in a marine teleost, the shi drum, that was recently introduced to the mariculture industry in southern Europe and emphasizes the conservation in the 5' UTR of IGF-I among teleosts. Furthermore, this study suggests, on the basis of a combined approach of RT-PCR, Real-Time PCR and immunohistochemistry that IGF-I and IGF-II are involved in the regulation of somatic growth in the shi drum.
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Affiliation(s)
- Marco Patruno
- Department of Experimental Veterinary Sciences, Faculty of Veterinary Medicine, University of Padua, Agripolis, 35020 Legnaro (PD), Italy.
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92
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Sacco A, Doyonnas R, LaBarge MA, Hammer MM, Kraft P, Blau HM. IGF-I increases bone marrow contribution to adult skeletal muscle and enhances the fusion of myelomonocytic precursors. ACTA ACUST UNITED AC 2006; 171:483-92. [PMID: 16275752 PMCID: PMC2171272 DOI: 10.1083/jcb.200506123] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle damage has been shown to enhance the contribution of bone marrow-derived cells (BMDCs) to regenerating skeletal muscle. One responsible cell type involved in this process is a hematopoietic stem cell derivative, the myelomonocytic precursor (MMC). However, the molecular components responsible for this injury-related response remain largely unknown. In this paper, we show that delivery of insulin-like growth factor I (IGF-I) to adult skeletal muscle by three different methods-plasmid electroporation, injection of genetically engineered myoblasts, and recombinant protein injection-increases the integration of BMDCs up to fourfold. To investigate the underlying mechanism, we developed an in vitro fusion assay in which co-cultures of MMCs and myotubes were exposed to IGF-I. The number of fusion events was substantially augmented by IGF-I, independent of its effect on cell survival. These results provide novel evidence that a single factor, IGF-I, is sufficient to enhance the fusion of bone marrow derivatives with adult skeletal muscle.
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Affiliation(s)
- Alessandra Sacco
- Department of Molecular Pharmacology, Baxter Laboratory in Genetic Pharmacology, Stanford University School of Medicine, Stanford, CA 94305, USA
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93
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94
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Urso ML, Fiatarone Singh MA, Ding W, Evans WJ, Cosmas AC, Manfredi TG. Exercise training effects on skeletal muscle plasticity and IGF-1 receptors in frail elders. AGE (DORDRECHT, NETHERLANDS) 2005; 27:117-125. [PMID: 23598617 PMCID: PMC3458497 DOI: 10.1007/s11357-005-1629-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Revised: 03/07/2005] [Accepted: 06/01/2005] [Indexed: 06/02/2023]
Abstract
Age-related sarcopenia inhibits mobility, increasing the risk for developing many diseases, including diabetes, arthritis, osteoporosis, and heart disease. Tissue plasticity, or the ability to regenerate following stress, has been a subject of question in aging humans. We assessed the impact of 10-weeks of resistance training on markers of skeletal muscle plasticity and insulin growth factor-1 (IGF-1) receptor density in a sub sample of subjects who, in an earlier study, demonstrated enhanced immunohistochemical labeling of IGF following resistance training. Muscle biopsies from the vastus lateralis of five elderly men and women were taken prior to and following 10 weeks of resistance training (N = 3) or a control period (N = 2). Immunogold labeling and quantitative electron microscopy techniques were used to analyze markers of IGF-1 receptor density and tissue plasticity. The experimental subjects showed a 161 ± 93.7% increase in Z band damage following resistance training. Myofibrillar central nuclei increased 296 ± 120% (P = 0. 029) in the experimental subjects. Changes in the percent of damaged Z bands were associated with alterations in the presence of central nuclei (r = 0.668; P = 0.0347). Post hoc analysis revealed that the relative pre/post percent changes in myofibrillar Z band damage and central nuclei were not statistically different between the control and exercise groups. Exercise training increased myofibrillar IGF-1 receptor densities in the exercise subjects (P = 0.008), with a non-significant increase in the control group. Labeling patterns suggested enhanced receptor density around the Z bands, sarcolemma, and mitochondrial and nuclear membranes. Findings from this study suggest that the age-related downregulation of the skeletal muscle IGF-1 system may be reversed to some extent with progressive resistance training. Furthermore, skeletal muscle tissue plasticity in the frail elderly is maintained at least to some extent as exemplified by the enhancement of IGF-1 receptor density and markers of tissue regeneration.
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Affiliation(s)
- Maria L. Urso
- Energy Metabolism Laboratory, University of Rhode Island, Kingston, RI 02881 USA
- Department of Exercise Science, University of Massachusetts, Amherst, MA 01003 USA
| | - Maria A. Fiatarone Singh
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111 USA
- School of Exercise and Sport Science, University of Sydney, Lidcombe, New South Whales 1825 Australia
| | - Wenjing Ding
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111 USA
| | - William J. Evans
- Donald W. Reynolds Department of Geriatrics and Geriatric Research, Education, and Clinical Center, University of Arkansas for Medical Sciences, Veterans Affairs Medical Center, Little Rock, AR 72114 USA
| | - Arthur C. Cosmas
- Allied Health Professions, University of Connecticut, Storrs, CT 06269 USA
| | - Thomas G. Manfredi
- Energy Metabolism Laboratory, University of Rhode Island, Kingston, RI 02881 USA
- Exercise Science, University of Rhode Island, 25 West Independence Way, Kingston, RI 02881 USA
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