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Lednev EM, Kravchenko IV, Furalyov VA, Lysenko EA, Lemesheva IS, Grushin AA, Dubrov VE, Vinogradova OL, Popov DV. Effect of amino acids on IGF1 gene expression in human myotubes and skeletal muscle. Growth Horm IGF Res 2020; 53-54:101323. [PMID: 32408253 DOI: 10.1016/j.ghir.2020.101323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 04/11/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Insulin-like growth factor I (IGF1) is an important regulator of collagen and extracellular matrix protein expression. We aimed to evaluate the effect of amino acids (AAs) on expression of IGF1 and IGF1-dependent genes in human myotubes and skeletal muscle and supposed that AAs administration increases IGF1 levels in blood and expression of IGF1 and IGF1-dependent genes in trained skeletal muscle, thereby reducing training-induced muscle damage. DESIGN Human myotubes were incubated with Arg and Leu for 24 h. Then, the effects of long-term branched chain AAs administration (10 weeks, 0.1 g/kg body mass/day) to volunteers (six subjects per AAs and placebo groups) performing large training volumes regularly (cross country skiers, training twice a day) were examined. RESULTS Incubating the myotubes with AAs increases expression of IGF1 mRNA isoforms and IGF1 secretion by 2-3 times. In athletes, long-term AAs administration increased basal blood levels of IGF1 (~50%) and expression of IGF1Ea mRNA slightly in skeletal muscle. There is no marked increase in expression of COL1A1, COL3A1, COL5A1, and LOX genes in skeletal muscle after AAs administration. However, expression of these genes in the combined group (placebo + AAs; n = 12) significantly correlated with the expression of IGF1Ea mRNA in muscle and did not correlate with IGF1 levels in the blood. CONCLUSIONS AAs administration increases IGF1 expression in vitro and in vivo. To obtain more pronounced changes in expression of IGF1 and IGF1-dependent genes in skeletal muscle, it may be necessary to increase the dose and/or duration of AAs administration.
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Affiliation(s)
- Egor M Lednev
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation.
| | - Irina V Kravchenko
- Federal Research Centre «Fundamentals of Biotechnology» of the Russian Academy of Sciences, 33 build 2, Leninsky prospect, Moscow 119071, Russian Federation
| | - Vladimir A Furalyov
- Federal Research Centre «Fundamentals of Biotechnology» of the Russian Academy of Sciences, 33 build 2, Leninsky prospect, Moscow 119071, Russian Federation
| | - Evgeny A Lysenko
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
| | - Iulia S Lemesheva
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
| | - Alexandr A Grushin
- Russian Olympic Committee, Luzhnetskaya Embankment 8, Russia, Moscow 119991, Russian Federation
| | - Vadim E Dubrov
- Lomonosov Moscow State University, Faculty of Fundamental Medicine, 27 build. 1, Lomonosovsky Prospekt, Moscow 119991, Russian Federation
| | - Olga L Vinogradova
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
| | - Daniil V Popov
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
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Kravchenko IV, Furalyov VA, Popov VO. Glycated albumin stimulates expression of inflammatory cytokines in muscle cells. Cytokine 2020; 128:154991. [PMID: 32000013 DOI: 10.1016/j.cyto.2020.154991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/17/2019] [Accepted: 01/07/2020] [Indexed: 12/19/2022]
Abstract
The effects of glycated albumin on the expression of inflammatory cytokines in differentiated myotubes were investigated. Glycated albumin stimulates the expression of TNF α, IL-1β, IL-6 and CCL-2 both at the mRNA and protein levels via the receptor of AGEs. Various cytokines demonstrated different kinetics of stimulation by glycated albumin. At a high glucose concentration, the stimulation effect was more pronounced than at a low one. At physiological concentrations of albumin and fructosamine, the stimulation effect of glycated albumin on inflammatory cytokine expression in myotubes was also observed. The induction of expression of all studied cytokines was sensitive to the inhibitors of JNK, p38 MAPK, MEK1/2, Src family protein kinases and NF-κB. At the same time, the induction of TNFα and IL-1β was diminished by the Ca2+/calmodulin-dependent protein kinase inhibitor, whereas the induction of IL-6 and CCL-2 was reduced by the inhibitor of phosphoinositide 3-kinase. Possible implications of observed stimulation of cytokine expression by glycated albumin in the development of diabetes mellitus symptoms are discussed.
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Affiliation(s)
- Irina V Kravchenko
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, bld. 2, Moscow 119071, Russia.
| | - Vladimir A Furalyov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, bld. 2, Moscow 119071, Russia
| | - Vladimir O Popov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, bld. 2, Moscow 119071, Russia
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López-Herradón A, Fujikawa R, Gómez-Marín M, Stedile-Lovatel JP, Mulero F, Ardura JA, Ruiz P, Muñoz I, Esbrit P, Mahíllo-Fernández I, Ortega-de Mues A. Impact of Chiropractic Manipulation on Bone and Skeletal Muscle of Ovariectomized Rats. Calcif Tissue Int 2017; 101:519-529. [PMID: 28755011 DOI: 10.1007/s00223-017-0304-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/12/2017] [Indexed: 01/01/2023]
Abstract
Evidence suggests that chiropractic manipulation might exert positive effects in osteoporotic patients. The aim of this study was to evaluate the effects of chiropractic manipulation on bone structure and skeletal muscle in rats with bone loss caused by ovariectomy (OVX). The 6-month old Sprague-Dawley rats at 10 weeks following OVX or sham operation (Sh) did not suffer chiropractic manipulation (NM group) or were submitted to true chiropractic manipulation using the chiropractic adjusting instrument Activator V® three times/week for 6 weeks as follows: Force 1 setting was applied onto the tibial tubercle of the rat right hind limb (TM group), whereas the corresponding left hind limb received a false manipulation (FM group) consisting of ActivatorV® firing in the air and slightly touching the tibial tubercle. Bone mineral density (BMD) and bone mineral content (BMC) were determined in long bones and L3-L4 vertebrae in all rats. Femora and tibia were analyzed by μCT. Mechano growth factor (MGF) was detected in long bones and soleus, quadriceps and tibial muscles by immunohistochemistry and Western blot. The decrease of BMD and BMC as well as trabecular bone impairment in the long bones of OVX rats vs Sh controls was partially reversed in the TM group versus FM or NM rats. This bone improvement by chiropractic manipulation was associated with an increased MGF expression in the quadriceps and the anterior tibial muscle in OVX rats. These findings support the notion that chiropractic manipulation can ameliorate osteoporotic bone at least partly by targeting skeletal muscle.
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Affiliation(s)
- A López-Herradón
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain
- Laboratorio de Metabolismo Mineral y Óseo, Instituto de Investigación Sanitaria (IIS)-Fundación Jiménez Díaz-UAM, Madrid, Spain
| | - R Fujikawa
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain
| | - M Gómez-Marín
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain
| | - J P Stedile-Lovatel
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain
| | - F Mulero
- Unidad de Imagen Molecular, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain
| | - J A Ardura
- Laboratorio de Metabolismo Mineral y Óseo, Instituto de Investigación Sanitaria (IIS)-Fundación Jiménez Díaz-UAM, Madrid, Spain
| | - P Ruiz
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain
| | - I Muñoz
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain
| | - P Esbrit
- Laboratorio de Metabolismo Mineral y Óseo, Instituto de Investigación Sanitaria (IIS)-Fundación Jiménez Díaz-UAM, Madrid, Spain
| | - I Mahíllo-Fernández
- Unidad de Epidemiología y Bioestadística, IIS-Fundación Jiménez Díaz-UAM, Madrid, Spain
| | - A Ortega-de Mues
- Madrid College of Chiropractic, Real Centro Universitario Escorial-María Cristina, Paseo de los Alamillos, 2, San Lorenzo de El Escorial, 28200, Madrid, Spain.
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Song Y, Yu C, Wang C, Ma X, Xu K, Zhong JL, Lv Y, Sung KP, Yang L. Mechano growth factor-C24E, a potential promoting biochemical factor for ligament tissue engineering. Biochem Eng J 2016. [DOI: 10.1016/j.bej.2015.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Liu Z, Kennedy OD, Cardoso L, Basta-Pljakic J, Partridge NC, Schaffler MB, Rosen CJ, Yakar S. DMP-1-mediated Ghr gene recombination compromises skeletal development and impairs skeletal response to intermittent PTH. FASEB J 2015; 30:635-52. [PMID: 26481310 DOI: 10.1096/fj.15-275859] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/28/2015] [Indexed: 12/20/2022]
Abstract
Bone minerals are acquired during growth and are key determinants of adult skeletal health. During puberty, the serum levels of growth hormone (GH) and its downstream effector IGF-1 increase and play critical roles in bone acquisition. The goal of the current study was to determine how bone cells integrate signals from the GH/IGF-1 to enhance skeletal mineralization and strength during pubertal growth. Osteocytes, the most abundant bone cells, were shown to orchestrate bone modeling during growth. We used dentin matrix protein (Dmp)-1-mediated Ghr knockout (DMP-GHRKO) mice to address the role of the GH/IGF axis in osteocytes. We found that DMP-GHRKO did not affect linear growth but compromised overall bone accrual. DMP-GHRKO mice exhibited reduced serum inorganic phosphate and parathyroid hormone (PTH) levels and decreased bone formation indices and were associated with an impaired response to intermittent PTH treatment. Using an osteocyte-like cell line along with in vivo studies, we found that PTH sensitized the response of bone to GH by increasing Janus kinase-2 and IGF-1R protein levels. We concluded that endogenously secreted PTH and GHR signaling in bone are necessary to establish radial bone growth and optimize mineral acquisition during growth.
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Affiliation(s)
- Zhongbo Liu
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Oran D Kennedy
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Luis Cardoso
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Jelena Basta-Pljakic
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Nicola C Partridge
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Mitchell B Schaffler
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Clifford J Rosen
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Shoshana Yakar
- *Department of Basic Science and Craniofacial Biology, David B. Kriser Dental Center, New York University College of Dentistry, New York, New York, USA; Department of Biomedical Engineering, City College of New York, New York, New York, USA; and Maine Medical Center Research Institute, Scarborough, Maine, USA
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Kravchenko IV, Furalyov VA, Chatziefthimiou S, Wilmanns M, Popov VO. Induction of insulin-like growth factor 1 splice forms by subfragments of myofibrillar proteins. Mol Cell Endocrinol 2015; 399:69-77. [PMID: 25152160 DOI: 10.1016/j.mce.2014.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/19/2014] [Accepted: 08/19/2014] [Indexed: 12/20/2022]
Abstract
Expression of insulin-like growth factor 1 (IGF-1) mRNAs splice forms was recently shown to be stimulated by myofibrillar proteins released from the damaged muscle. In this study, we report that individual subfragments of titin and myomesin composed of Fn type III and Ig-like domains can activate expression of two IGF-1 splice forms in cultured myoblasts, both at protein and mRNA levels. Competition studies showed that each of the domain-types interacts with its own receptor. Induction of IGF-1 expression caused by domains of different types showed dissimilar sensitivity to inhibitors of regulatory cascades. The effect of Fn type III domains was more sensitive to inhibition of Ca(2+)/calmodulin dependent protein kinase, whereas the effect of Ig-like domains showed greater sensitivity to the inhibition of the adenylyl cyclase-cAMP-PKA pathway.
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Affiliation(s)
- Irina V Kravchenko
- Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskiy Prospect 33, 119071 Moscow, Russia
| | - Vladimir A Furalyov
- Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskiy Prospect 33, 119071 Moscow, Russia
| | - Spyros Chatziefthimiou
- European Molecular Biology Laboratory, Hamburg Unit, c/o DESY, Notkestraße 85, 22603 Hamburg, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, c/o DESY, Notkestraße 85, 22603 Hamburg, Germany
| | - Vladimir O Popov
- Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskiy Prospect 33, 119071 Moscow, Russia; Kurchatov NBIC Centre, Russian National Research Centre "Kurchatov Institute", Akademika Kurchatova sq. 1, 123182 Moscow, Russia.
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Zinevich LS, Goncharova NO, Uryvaeva IV, Delone GV, Mikaelyan AS. Igf-1 and its isoform expression in hepatic cell tumors and the surrounding tissue in mice liver carcinogenesis induced by diethylnitrozamine. BIOL BULL+ 2013. [DOI: 10.1134/s1062359013060150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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8
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Liu H, Tang L. Mechano-regulation of alternative splicing. Curr Genomics 2013; 14:49-55. [PMID: 23997650 PMCID: PMC3580779 DOI: 10.2174/138920213804999156] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 11/22/2012] [Accepted: 12/23/2012] [Indexed: 01/29/2023] Open
Abstract
Alternative splicing contributes to the complexity of proteome by producing multiple mRNAs from a single gene. Affymetrix exon arrays and experiments in vivo or in vitro demonstrated that alternative splicing was regulated by mechanical stress. Expression of mechano-growth factor (MGF) which is the splicing isoform of insulin-like growth factor 1(IGF-1) and vascular endothelial growth factor (VEGF) splicing variants such as VEGF121, VEGF165, VEGF206, VEGF189, VEGF165 and VEGF145 are regulated by mechanical stress. However, the mechanism of this process is not yet clear. Increasing evidences showed that the possible mechanism is related to Ca2+ signal pathway and phosphorylation signal pathway. This review proposes possible mechanisms of mechanical splicing regulation. This will contribute to the biomechanical study of alternative splicing.
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Affiliation(s)
- Huan Liu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
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Abstract
This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases, cyclooxygenases, and cytochrome P-450, seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator-activated receptors or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C) and other transcription factors (nuclear factor kappa B and sterol regulatory element binding protein). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer and provide insight into the development of new therapeutic strategies for a better management of whole body lipid metabolism.
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Age-related loss of muscle mass and strength. J Aging Res 2012; 2012:158279. [PMID: 22506111 PMCID: PMC3312297 DOI: 10.1155/2012/158279] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 11/07/2011] [Indexed: 11/26/2022] Open
Abstract
Age-related muscle wasting and increased frailty are major socioeconomic as well as medical problems. In the quest to extend quality of life it is important to increase the strength of elderly people sufficiently so they can carry out everyday tasks and to prevent them falling and breaking bones that are brittle due to osteoporosis. Muscles generate the mechanical strain that contributes to the maintenance of other musculoskeletal tissues, and a vicious circle is established as muscle loss results in bone loss and weakening of tendons. Molecular and proteomic approaches now provide strategies for preventing age-related muscle wasting. Here, attention is paid to the role of the GH/IGF-1 axis and the special role of the IGFI-Ec (mechano growth factor/MGF) which is derived from the IGF-I gene by alternative splicing. During aging MGF levels decline but when administered MGF activates the muscle satellite (stem) cells that “kick start” local muscle repair and induces hypertrophy.
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Kravchenko IV, Furalyov VA, Popov VO. Stimulation of mechano-growth factor expression by myofibrillar proteins in murine myoblasts and myotubes. Mol Cell Biochem 2011; 363:347-55. [PMID: 22160926 DOI: 10.1007/s11010-011-1187-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 11/24/2011] [Indexed: 10/14/2022]
Abstract
Mechano-growth factor (MGF) is a product of alternative splicing of the insulin-like growth factor 1 (IGF-1) mRNA. MGF is known to stimulate myoblast proliferation and to protect neurons and cardiomyocytes from apoptosis. MGF expression is dramatically increased in response to mechanical stimuli and tissue damage. The mechanisms of induction of MGF expression are as yet imperfectly understood. There is certain evidence that some protein factors able to stimulate MGF synthesis in normal myoblasts are released from damaged muscle. This study was undertaken to explore the nature of these protein inductors of MGF expression and to investigate the mechanism of their action. We report here that myofibrillar fraction of skeletal muscle homogenate activated MGF expression in murine myoblasts and myotubes in culture. The expression of another splice form of IGF-1 gene, IGF-1Ea, was also stimulated by myofibrils. Three myofibrillar proteins able to stimulate MGF synthesis were isolated. These proteins were identified by MALDI and immunoblotting as myomesin, myosin-binding protein C, and titin. The activation of MGF expression was associated with the increase of cAMP level in the cells. Inhibitor of adenylyl cyclase dideoxyadenosine arrested stimulation of MGF synthesis by all three myofibrillar proteins.
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Affiliation(s)
- Irina V Kravchenko
- A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskiy Prospect 33, 119071 Moscow, Russia.
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Reactive oxygen species in skeletal muscle signaling. JOURNAL OF SIGNAL TRANSDUCTION 2011; 2012:982794. [PMID: 22175016 PMCID: PMC3235811 DOI: 10.1155/2012/982794] [Citation(s) in RCA: 249] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 08/25/2011] [Indexed: 12/13/2022]
Abstract
Generation of reactive oxygen species (ROS) is a ubiquitous phenomenon in eukaryotic cells' life. Up to the 1990s of the past century, ROS have been solely considered as toxic species resulting in oxidative stress, pathogenesis and aging. However, there is now clear evidence that ROS are not merely toxic species but also-within certain concentrations-useful signaling molecules regulating physiological processes. During intense skeletal muscle contractile activity myotubes' mitochondria generate high ROS flows: this renders skeletal muscle a tissue where ROS hold a particular relevance. According to their hormetic nature, in muscles ROS may trigger different signaling pathways leading to diverging responses, from adaptation to cell death. Whether a "positive" or "negative" response will prevail depends on many variables such as, among others, the site of ROS production, the persistence of ROS flow or target cells' antioxidant status. In this light, a specific threshold of physiological ROS concentrations above which ROS exert negative, toxic effects is hard to determine, and the concept of "physiologically compatible" levels of ROS would better fit with such a dynamic scenario. In this review these concepts will be discussed along with the most relevant signaling pathways triggered and/or affected by ROS in skeletal muscle.
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