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Kant S, Davuluri G, Alchirazi KA, Welch N, Heit C, Kumar A, Gangadhariah M, Kim A, McMullen MR, Willard B, Luse DS, Nagy LE, Vasiliou V, Marini AM, Weiner ID, Dasarathy S. Ethanol sensitizes skeletal muscle to ammonia-induced molecular perturbations. J Biol Chem 2019; 294:7231-7244. [PMID: 30872403 DOI: 10.1074/jbc.ra118.005411] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 03/12/2019] [Indexed: 12/27/2022] Open
Abstract
Ethanol causes dysregulated muscle protein homeostasis while simultaneously causing hepatocyte injury. Because hepatocytes are the primary site for physiological disposal of ammonia, a cytotoxic cellular metabolite generated during a number of metabolic processes, we determined whether hyperammonemia aggravates ethanol-induced muscle loss. Differentiated murine C2C12 myotubes, skeletal muscle from pair-fed or ethanol-treated mice, and human patients with alcoholic cirrhosis and healthy controls were used to quantify protein synthesis, mammalian target of rapamycin complex 1 (mTORC1) signaling, and autophagy markers. Alcohol-metabolizing enzyme expression and activity in mouse muscle and myotubes and ureagenesis in hepatocytes were quantified. Expression and regulation of the ammonia transporters, RhBG and RhCG, were quantified by real-time PCR, immunoblots, reporter assays, biotin-tagged promoter pulldown with proteomics, and loss-of-function studies. Alcohol and aldehyde dehydrogenases were expressed and active in myotubes. Ethanol exposure impaired hepatocyte ureagenesis, induced muscle RhBG expression, and elevated muscle ammonia concentrations. Simultaneous ethanol and ammonia treatment impaired protein synthesis and mTORC1 signaling and increased autophagy with a consequent decreased myotube diameter to a greater extent than either treatment alone. Ethanol treatment and withdrawal followed by ammonia exposure resulted in greater impairment in muscle signaling and protein synthesis than ammonia treatment in ethanol-naive myotubes. Of the three transcription factors that were bound to the RhBG promoter in response to ethanol and ammonia, DR1/NC2 indirectly regulated transcription of RhBG during ethanol and ammonia treatment. Direct effects of ethanol were synergistic with increased ammonia uptake in causing dysregulated skeletal muscle proteostasis and signaling perturbations with a more severe sarcopenic phenotype.
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Affiliation(s)
- Sashi Kant
- From the Departments of Inflammation and Immunity
| | | | | | - Nicole Welch
- From the Departments of Inflammation and Immunity
| | - Claire Heit
- the Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | | | | | - Adam Kim
- From the Departments of Inflammation and Immunity
| | | | - Belinda Willard
- Metabolomic and Proteomics Core, Cleveland Clinic, Cleveland, Ohio 44195
| | | | - Laura E Nagy
- From the Departments of Inflammation and Immunity
| | - Vasilis Vasiliou
- the Department of Environmental Health Sciences, Yale School of Public Health, New Haven, Connecticut 06510
| | - Anna Maria Marini
- the Biology of Membrane Transport Laboratory, Department of Molecular Biology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles CP300, 6041 Gosselies, Belgium
| | - I David Weiner
- the Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, School of Medicine, University of Florida, Gainesville, Florida 32610, and.,the Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida 32608
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Lang CH. Lack of sexual dimorphism on the inhibitory effect of alcohol on muscle protein synthesis in rats under basal conditions and after anabolic stimulation. Physiol Rep 2018; 6:e13929. [PMID: 30512248 PMCID: PMC6278815 DOI: 10.14814/phy2.13929] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/25/2018] [Accepted: 10/26/2018] [Indexed: 11/24/2022] Open
Abstract
Previous studies indicate women have a higher blood alcohol (i.e., ethanol) and acetaldehyde concentration after consuming an equivalent amount of alcohol, and that women are more susceptible to the long-term negative health effects of alcohol. However, there is a paucity of data pertaining to whether there is a sexual dimorphic response in skeletal muscle to alcohol. Adult male and female Sprague-Dawley rats were used and the primary endpoint was in vivo determined muscle (gastrocnemius) protein synthesis (MPS). The initial study indicated MPS did not differ in female rats during proestrus, estrus, metestrus, or diestrus; hence, subsequent studies used female rats irrespective of estrus cycle phase. There was no difference in MPS between male and female rats under basal fasted conditions, and the time- and dose-responsiveness of both groups to the inhibitory effect of acute alcohol did not differ. The ability of alcohol to suppress MPS was comparable in male and female rats pretreated with alcohol dehydrogenase inhibitor 4-methylpyrazol. Chronic alcohol feeding for 6 weeks decreased MPS in male but not in female rats; however, MPS was reduced in both sexes at 14 weeks. Finally, oral gavage of leucine increased MPS similarly in male and female rats and chronic alcohol feeding for 14 weeks prevented the anabolic effect in both sexes. These data suggest normal fluctuations in ovarian hormones do not significantly alter MPS in female rats, and that there is no sexual dimorphic response to the effects of acute alcohol intoxication on MPS. While chronic alcohol consumption appeared to decrease MPS at an early time point in male compared to female rats, there was no sex difference in the suppressive effect of alcohol at a later time point. Overall, these data do not support the prevailing belief that females are more susceptible than males to alcohol's catabolic effect on MPS.
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Affiliation(s)
- Charles H. Lang
- Department of Cellular and Molecular PhysiologyPenn State College of MedicineHersheyPennsylvania
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Shenkman BS, Belova SP, Zinovyeva OE, Samkhaeva ND, Mirzoev TM, Vilchinskaya NA, Altaeva EG, Turtikova OV, Kostrominova TY, Nemirovskaya TL. Effect of Chronic Alcohol Abuse on Anabolic and Catabolic Signaling Pathways in Human Skeletal Muscle. Alcohol Clin Exp Res 2017; 42:41-52. [PMID: 29044624 DOI: 10.1111/acer.13531] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/10/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Animal studies showed that alcoholic myopathy is characterized by the reduction in myofiber cross-sectional area (CSA) and by impaired anabolic signaling. The goal of this study was to compare changes in CSA and fiber type composition with modifications in anabolic and catabolic signaling pathways at the early stages of alcohol misuse in humans. METHODS Skeletal muscle samples from 7 male patients with chronic alcohol abuse (AL; 47.7 ± 2.0 years old; alcohol misuse duration 7.7 ± 0.6 years) were compared with muscle from a control group of 7 healthy men (C; 39.7 ± 5.0 years old). Biopsies from vastus lateralis muscles were taken and analyzed for the changes in fiber type composition, fiber CSA, and for the alterations in anabolic and catabolic signaling pathways. RESULTS AL patients did not have detectable clinical myopathy symptoms or muscle fiber atrophy, but the relative proportion of fast fibers was increased. There was a significant decrease in IGF-1 in plasma and IRS-1 protein content in muscle of AL group. Levels of total and phosphorylated p70S6K1, GSK3β, and p90RSK1 were not different between AL and C groups. Muscle of AL patients had increased mRNA expression of HSP70 and HSP90. A marker of anabolic pathway p-4E-BP1 was decreased, while catabolic markers (MuRF-1, MAFbx, ubiquitinated proteins) were increased in AL patients when compared with C group. CONCLUSIONS At the early stages of alcohol misuse in humans, changes in the regulation of anabolic and catabolic signaling pathways precede the development of skeletal muscle atrophy and manifestation of clinical symptoms of alcoholic myopathy.
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Affiliation(s)
| | | | - Olga E Zinovyeva
- Sechenov First Moscow State Medical University, Russian Ministry of Health, Moscow, Russia
| | - Nudlya D Samkhaeva
- Sechenov First Moscow State Medical University, Russian Ministry of Health, Moscow, Russia
| | | | | | | | | | - Tatiana Y Kostrominova
- Department of Anatomy and Cell Biology, Indiana University School of Medicine Northwest, Gary, Indiana
| | - Tatiana L Nemirovskaya
- Institute of Biomedical Problems, RAS, Moscow, Russia.,Faculty of Basic Medicine, Lomonosov Moscow State University, Moscow, Russia
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Manring H, Abreu E, Brotto L, Weisleder N, Brotto M. Novel excitation-contraction coupling related genes reveal aspects of muscle weakness beyond atrophy-new hopes for treatment of musculoskeletal diseases. Front Physiol 2014; 5:37. [PMID: 24600395 PMCID: PMC3927072 DOI: 10.3389/fphys.2014.00037] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/18/2014] [Indexed: 12/16/2022] Open
Abstract
Research over the last decade strengthened the understanding that skeletal muscles are not only the major tissue in the body from a volume point of view but also function as a master regulator contributing to optimal organismal health. These new contributions to the available body of knowledge triggered great interest in the roles of skeletal muscle beyond contraction. The World Health Organization, through its Global Burden of Disease (GBD) report, recently raised further awareness about the key importance of skeletal muscles as the GDB reported musculoskeletal (MSK) diseases have become the second greatest cause of disability, with more than 1.7 billion people in the globe affected by a diversity of MSK conditions. Besides their role in MSK disorders, skeletal muscles are also seen as principal metabolic organs with essential contributions to metabolic disorders, especially those linked to physical inactivity. In this review, we have focused on the unique function of new genes/proteins (i.e., MTMR14, MG29, sarcalumenin, KLF15) that during the last few years have helped provide novel insights about muscle function in health and disease, muscle fatigue, muscle metabolism, and muscle aging. Next, we provide an in depth discussion of how these genes/proteins converge into a common function of acting as regulators of intracellular calcium homeostasis. A clear link between dysfunctional calcium homeostasis is established and the special role of store-operated calcium entry is analyzed. The new knowledge that has been generated by the understanding of the roles of previously unknown modulatory genes of the skeletal muscle excitation-contraction coupling (ECC) process brings exciting new possibilities for treatment of MSK diseases, muscle regeneration, and skeletal muscle tissue engineering. The next decade of skeletal muscle and MSK research is bound to bring to fruition applied knowledge that will hopefully offset the current heavy and sad burden of MSK diseases on the planet.
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Affiliation(s)
- Heather Manring
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
| | - Eduardo Abreu
- Muscle Biology Research Group, School of Nursing and Health Studies, University of Missouri-Kansas City Kansas City, MO, USA
| | - Leticia Brotto
- Muscle Biology Research Group, School of Nursing and Health Studies, University of Missouri-Kansas City Kansas City, MO, USA
| | - Noah Weisleder
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
| | - Marco Brotto
- Muscle Biology Research Group, School of Nursing and Health Studies, University of Missouri-Kansas City Kansas City, MO, USA ; Basic Medical Sciences Pharmacology, School of Medicine, University of Missouri-Kansas City Kansas City, MO, USA ; Basic Medical Sciences Pharmacology, School of Pharmacy, University of Missouri-Kansas City Kansas City, MO, USA
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Sandoval-Montiel AA, Zentella-de-Piña M, Ventura-Gallegos JL, Frías-González S, López-Macay A, Zentella-Dehesa A. HSP-72 accelerated expression in mononuclear cells induced in vivo by acetyl salicylic acid can be reproduced in vitro when combined with H2O2. PLoS One 2013; 8:e65449. [PMID: 23762376 PMCID: PMC3675067 DOI: 10.1371/journal.pone.0065449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 04/30/2013] [Indexed: 11/19/2022] Open
Abstract
Background Among NSAIDs acetyl salicylic acid remains as a valuable tool because of the variety of benefic prophylactic and therapeutic effects. Nevertheless, the molecular bases for these responses have not been complete understood. We explored the effect of acetyl salicylic acid on the heat shock response. Results Peripheral blood mononuclear cells from rats challenged with acetyl salicylic acid presented a faster kinetics of expression of HSP-72 messenger RNA and protein in response to in vitro heat shock. This effect reaches its maximum 2 h after treatment and disappeared after 5 h. On isolated peripheral blood mononuclear cells from untreated rats, incubation with acetyl salicylic acid was ineffective to produce priming, but this effect was mimicked when the cells were incubated with the combination of H2O2+ ASA. Conclusions Administration of acetyl salicylic acid to rats alters HSP-72 expression mechanism in a way that it becomes more efficient in response to in vitro heat shock. The fact that in vitro acetyl salicylic acid alone did not induce this priming effect implies that in vivo other signals are required. Priming could be reproduces in vitro with the combination of acetyl salicylic acid+H2O2.
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Affiliation(s)
- Alvaro A. Sandoval-Montiel
- Departmento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F., México
- Unidad de Bioquímica, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México, D.F., México
| | - Martha Zentella-de-Piña
- Departmento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, México, D.F., México
| | - José L. Ventura-Gallegos
- Departmento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F., México
| | - Susana Frías-González
- Departmento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F., México
| | - Ambar López-Macay
- Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación, México D.F., México
| | - Alejandro Zentella-Dehesa
- Departmento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F., México
- Unidad de Bioquímica, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México, D.F., México
- * E-mail:
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Islam A, Abraham P, Hapner CD, Deuster PA, Chen Y. Tissue-specific upregulation of HSP72 in mice following short-term administration of alcohol. Cell Stress Chaperones 2013; 18:215-22. [PMID: 23011927 PMCID: PMC3581633 DOI: 10.1007/s12192-012-0375-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/13/2012] [Accepted: 09/14/2012] [Indexed: 12/24/2022] Open
Abstract
Oxidative stress and cellular injury have been implicated in induction of HSP72 by alcohol. We investigated the association between HSP72 induction and oxidative stress in mouse tissues following short-term administration of high doses of alcohol and caffeine alone or in combination. Adult male C57BL/6J mice were gavaged with vehicle, alcohol (∼1.7 g/kg/day), caffeine (∼44 mg/kg/day), or alcohol plus caffeine once daily for ten consecutive days. Upon completion of the treatments, tissues were collected for structural and biochemical analyses. Alcohol alone caused mild to moderate lesions in heart, liver, and gastrocnemius muscle. Similar structural changes were observed following administration of alcohol and caffeine combined. Alcohol administration also led to decreased glutathione levels in all three tissues and reduced plasma superoxide dismutase capacity. In contrast, alcohol and caffeine in combination reduced glutathione levels only in liver and gastrocnemius muscle and had no effect on plasma superoxide dismutase. Significant elevations in HSP72 protein and mRNA and in HSF1 protein levels were noted only in liver by alcohol alone or in combination with caffeine. No significant changes in morphology and HSP72 were detected in any tissues tested following administration of caffeine alone. These results suggest that a redox mechanism is involved in the structural impairment caused by short-term high-dose alcohol. Oxidative tissue injury by alcohol may not be associated with tissue HSP72 induction. Induction of HSP72 in liver by alcohol is mediated at both the transcriptional and translational levels.
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Affiliation(s)
- Aminul Islam
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Preetha Abraham
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Christopher D. Hapner
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Patricia A. Deuster
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Yifan Chen
- Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
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Wang H, Li K, Zhu JY, Fang Q, Ye GY, Wang H, Li K, Zhu JY. Cloning and expression pattern of heat shock protein genes from the endoparasitoid wasp, Pteromalus puparum in response to environmental stresses. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2012; 79:247-263. [PMID: 22517445 DOI: 10.1002/arch.21013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Six heat shock protein (HSP) genes from five HSP families in the parasitoid, Pteromalus puparum, were evaluated for their response to temperature (-15 ~ 3°C , and 30 ~ 42°C for 1 h), heavy metals (0.5 ~ 5 mM Cd(2+) and Cu(2+) for 24 h and 60 h), and starvation (24 h). Compared with other insect HSPs, all conserved motifs are found in P. puparum HSPs, and they are very similar to those of the recently sequenced ectoparasitoid Nasonia vitripennis. The temporal gene expression patterns indicated that these six HSP genes were all heat-inducible, of which hsp40 was the most inducible. The temperatures for maximal HSP induction at high and low temperature zone were 36 or 39°C and -3°C, respectively. In the hot zone, all HSP genes have the same initial temperature (33°C) for up-regulation. Low concentrations of Cd(2+) for a short-term promoted the expression of all HSP genes, but not high concentrations or long-term treatments. Cu(2+) stress for 24 h increased expression of nearly all HSP. Four HSP genes changed after starvation. We infer that all six HSP genes are sensitive to heat. This may help understand the absence of P. puparum during the summer and winter. The expression profiles of six HSP genes in P. puparum under heavy metal stress indicates that HSP is a short-term response to cellular distress or injury induced by Cd(2+) and Cu(2+).
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Affiliation(s)
- Huan Wang
- State Key Laboratory of Rice Biology, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
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Mandrekar P, Catalano D, Jeliazkova V, Kodys K. Alcohol exposure regulates heat shock transcription factor binding and heat shock proteins 70 and 90 in monocytes and macrophages: implication for TNF-alpha regulation. J Leukoc Biol 2008; 84:1335-45. [PMID: 18689673 PMCID: PMC2567895 DOI: 10.1189/jlb.0407256] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/10/2008] [Accepted: 06/12/2008] [Indexed: 01/09/2023] Open
Abstract
Immunomodulatory effects of alcohol use involve regulation of innate immune cell function leading to liver disease. Alteration of inflammatory responses by alcohol is linked to dysregulated TNF-alpha production. Alcohol-induced oxidative stress also contributes to alterations in inflammatory cell activity. Heat shock proteins (hsps) and the heat shock transcription factor-1 (HSF-1) induced by oxidative stress regulate NF-kappaB activation and TNF-alpha gene expression in monocytes and macrophages. Here, we report that in vitro alcohol treatment induced and augmented LPS-induced HSF-1 nuclear translocation and DNA-binding activity in monocytes and macrophages. Supershift analysis revealed that alcohol regulated HSF-1- and not HSF-2-binding activity. Hsp70, a target gene induced by HSF-1, was transiently increased within 24 h by alcohol, but extended alcohol exposure decreased hsp70 in macrophages. The alcohol-induced alteration of hsp70 correlated with a concomitant change in hsp70 promoter activity. Hsp90, another HSF-1 target gene, was decreased during short-term alcohol but increased after prolonged alcohol exposure. Decreased hsp90-HSF-1 complexes after short-term alcohol indicated dissociation of HSF-1 from hsp90. On the other hand, hsp90 interacted with client protein IkappaB kinase beta, a signaling intermediate of the LPS pathway, followed by IkappaBalpha degradation and increased NF-kappaB activity after chronic alcohol exposure, indicating that hsp90 plays an important role in supporting inflammatory cytokine production. Inhibition of hsp90 using geldanamycin prevented prolonged alcohol-induced elevation in LPS-induced NF-kappaB and TNF-alpha production. These results suggest that alcohol exposure differentially regulates hsp70 and hsp90 via HSF-1 activation. Further, hsp90 regulates TNF-alpha production in macrophages contributing to alcohol-induced inflammation.
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Affiliation(s)
- Pranoti Mandrekar
- Department of Medicine, University of Massachusetts Medical Center, Worcester, Massachusetts 01605, USA.
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Fernandez-Solà J, Preedy VR, Lang CH, Gonzalez-Reimers E, Arno M, Lin JCI, Wiseman H, Zhou S, Emery PW, Nakahara T, Hashimoto K, Hirano M, Santolaria-Fernández F, González-Hernández T, Fatjó F, Sacanella E, Estruch R, Nicolás JM, Urbano-Márquez A. Molecular and cellular events in alcohol-induced muscle disease. Alcohol Clin Exp Res 2008; 31:1953-62. [PMID: 18034690 DOI: 10.1111/j.1530-0277.2007.00530.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Alcohol consumption induces a dose-dependent noxious effect on skeletal muscle, leading to progressive functional and structural damage of myocytes, with concomitant reductions in lean body mass. Nearly half of high-dose chronic alcohol consumers develop alcoholic skeletal myopathy. The pathogenic mechanisms that lie between alcohol intake and loss of muscle tissue involve multiple pathways, making the elucidation of the disease somewhat difficult. This review discusses the recent advances in basic and clinical research on the molecular and cellular events involved in the development of alcohol-induced muscle disease. The main areas of recent research interest on this field are as follows: (i) molecular mechanisms in alcohol exposed muscle in the rat model; (ii) gene expression changes in alcohol exposed muscle; (iii) the role of trace elements and oxidative stress in alcoholic myopathy; and (iv) the role of apoptosis and preapoptotic pathways in alcoholic myopathy. These aforementioned areas are crucial in understanding the pathogenesis of this disease. For example, there is overwhelming evidence that both chronic alcohol ingestion and acute alcohol intoxication impair the rate of protein synthesis of myofibrillar proteins, in particular, under both postabsorptive and postprandial conditions. Perturbations in gene expression are contributory factors to the development of alcoholic myopathy, as ethanol-induced alterations are detected in over 400 genes and the protein profile (i.e., the proteome) of muscle is also affected. There is supportive evidence that oxidative damage is involved in the pathogenesis of alcoholic myopathy. Increased lipid peroxidation is related to muscle fibre atrophy, and reduced serum levels of some antioxidants may be related to loss of muscle mass and muscle strength. Finally, ethanol induces skeletal muscle apoptosis and increases both pro- and antiapoptotic regulatory mechanisms.
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