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Bittel AJ, Chen YW. DNA Methylation in the Adaptive Response to Exercise. Sports Med 2024; 54:1419-1458. [PMID: 38561436 DOI: 10.1007/s40279-024-02011-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2024] [Indexed: 04/04/2024]
Abstract
Emerging evidence published over the past decade has highlighted the role of DNA methylation in skeletal muscle function and health, including as an epigenetic transducer of the adaptive response to exercise. In this review, we aim to synthesize the latest findings in this field to highlight: (1) the shifting understanding of the genomic localization of altered DNA methylation in response to acute and chronic aerobic and resistance exercise in skeletal muscle (e.g., promoter, gene bodies, enhancers, intergenic regions, un-annotated regions, and genome-wide methylation); (2) how these global/regional methylation changes relate to transcriptional activity following exercise; and (3) the factors (e.g., individual demographic or genetic features, dietary, training history, exercise parameters, local epigenetic characteristics, circulating hormones) demonstrated to alter both the pattern of DNA methylation after exercise, and the relationship between DNA methylation and gene expression. Finally, we discuss the changes in non-CpG methylation and 5-hydroxymethylation after exercise, as well as the importance of emerging single-cell analyses to future studies-areas of increasing focus in the field of epigenetics. We anticipate that this review will help generate a framework for clinicians and researchers to begin developing and testing exercise interventions designed to generate targeted changes in DNA methylation as part of a personalized exercise regimen.
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Affiliation(s)
- Adam J Bittel
- Research Center for Genetic Medicine, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA.
| | - Yi-Wen Chen
- Research Center for Genetic Medicine, Children's National Hospital, 111 Michigan Ave NW, Washington, DC, 20010, USA
- Department of Genomics and Precision Medicine, The George Washington University School of Medicine and Health Science, 111 Michigan Ave NW, Washington, DC, 20010, USA
- Department of Integrative Systems Biology, Institute for Biomedical Sciences, The George Washington University, 2121 I St NW, Washington, DC, 20052, USA
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2
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Romero MA, Mumford PW, Roberson PA, Osburn SC, Young KC, Sedivy JM, Roberts MD. Translational Significance of the LINE-1 Jumping Gene in Skeletal Muscle. Exerc Sport Sci Rev 2022; 50:185-193. [PMID: 35749745 PMCID: PMC9651911 DOI: 10.1249/jes.0000000000000301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Retrotransposons are gene segments that proliferate in the genome, and the Long INterspersed Element 1 (LINE-1 or L1) retrotransposon is active in humans. Although older mammals show enhanced skeletal muscle L1 expression, exercise generally reverses this trend. We hypothesize skeletal muscle L1 expression influences muscle physiology, and additional innovative investigations are needed to confirm this hypothesis.
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Affiliation(s)
- Matthew A. Romero
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California USA
| | - Petey W. Mumford
- Department of Exercise Science, Lindenwood University, St. Charles, Missouri USA
| | - Paul A. Roberson
- Department of Cellular and Molecular Physiology, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania USA
| | | | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, Alabama USA
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn, Auburn, Alabama, USA
| | - John M. Sedivy
- Department of Molecular Biology, Cell Biology and Biochemistry, Center on the Biology of Aging, Brown University, Providence, Rhode Island, USA
| | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama USA
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn, Auburn, Alabama, USA
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Osburn SC, Mesquita P, Neal FK, Rumbley M, Holmes MT, Ruple BA, Mobley CB, Brown MD, McCullough DJ, Kavazis AN, Roberts MD. Long-term voluntary wheel running effects on markers of Long Interspersed Nuclear Element-1 in skeletal muscle, liver, and brain tissue of female rats. Am J Physiol Cell Physiol 2022; 323:C907-C919. [PMID: 35938680 DOI: 10.1152/ajpcell.00234.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We sought to determine the effects of long-term voluntary wheel running on markers of Long Interspersed Nuclear Element-1 (L1) in skeletal muscle, liver, and the hippocampus of female rats. Additionally, markers of the cGAS-STING DNA sensing pathway that results in inflammation were interrogated. Female Lewis rats (n=34) were separated into one of three groups including a 6-month-old group to serve as a young comparator group (CTL, n=10), a group that had access to a running wheel for voluntary wheel running (EX, n=12), and an age-matched group that did not (SED, n=12). Both SED and EX groups were carried out from 6 months to 15 months of age. There were no significant differences in L1 mRNA expression for any of the tissues between groups. Methylation of the L1 promoter in the soleus and hippocampus was significantly higher in SED and EX compared to CTL (p<0.05). ORF1p expression was higher in older SED and EX rats compared to CTL for every tissue (p<0.05). There were no differences between groups for L1 mRNA or cGAS-STING pathway markers. Our results suggest there is an increased ORF1 protein expression across tissues with aging that is not mitigated by voluntary wheel running. Additionally, while previous data imply that L1 methylation changes may play a role in acute exercise for L1 RNA expression, this does not seem to occur during extended periods of voluntary wheel running.
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Affiliation(s)
- Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Paulo Mesquita
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Frances K Neal
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Melissa Rumbley
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Matthew T Holmes
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Bradley A Ruple
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - C Brooks Mobley
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Michael D Brown
- School of Public Health, University of Maryland, College Park, MD, United States
| | - Danielle J McCullough
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Edward Via College of Osteopathic Medicine, Auburn, AL, United States
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Edward Via College of Osteopathic Medicine, Auburn, AL, United States
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Vann CG, Haun CT, Osburn SC, Romero MA, Roberson PA, Mumford PW, Mobley CB, Holmes HM, Fox CD, Young KC, Roberts MD. Molecular Differences in Skeletal Muscle After 1 Week of Active vs. Passive Recovery From High-Volume Resistance Training. J Strength Cond Res 2021; 35:2102-2113. [PMID: 34138821 DOI: 10.1519/jsc.0000000000004071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
ABSTRACT Vann, CG, Haun, CT, Osburn, SC, Romero, MA, Roberson, PA, Mumford, PW, Mobley, CB, Holmes, HM, Fox, CD, Young, KC, and Roberts, MD. Molecular differences in skeletal muscle after 1 week of active vs. passive recovery from high-volume resistance training. J Strength Cond Res 35(8): 2102-2113, 2021-Numerous studies have evaluated how deloading after resistance training (RT) affects strength and power outcomes. However, the molecular adaptations that occur after deload periods remain understudied. Trained, college-aged men (n = 30) performed 6 weeks of whole-body RT starting at 10 sets of 10 repetitions per exercise per week and finishing at 32 sets of 10 repetitions per exercise per week. After this period, subjects performed either active (AR; n = 16) or passive recovery (PR; n = 14) for 1 week where AR completed ∼15% of the week 6 training volume and PR ceased training. Variables related to body composition and recovery examined before RT (PRE), after 6 weeks of RT (POST), and after the 1-week recovery period (DL). Vastus lateralis (VL) muscle biopsies and blood samples were collected at each timepoint, and various biochemical and histological assays were performed. Group × time interactions (p < 0.05) existed for skeletal muscle myosin heavy chain (MHC)-IIa mRNA (AR > PR at POST and DL) and 20S proteasome activity (post-hoc tests revealed no significance in groups over time). Time effects (P < 0.05) existed for total mood disturbance and serum creatine kinase and mechano growth factor mRNA (POST > PRE &D L), VL pressure to pain threshold and MHC-IIx mRNA (PRE&DL > POST), Atrogin-1 and MuRF-1 mRNA (PRE < POST < DL), MHC-I mRNA (PRE < POST & DL), myostatin mRNA (PRE & POST < DL), and mechanistic target of rapamycin (PRE > POST & DL). No interactions or time effects were observed for barbell squat velocity, various hormones, histological metrics, polyubiquitinated proteins, or phosphorylated/pan protein levels of 4E-BP1, p70S6k, and AMPK. One week of AR after a high-volume training block instigates marginal molecular differences in skeletal muscle relative to PR. From a practical standpoint, however, both paradigms elicited largely similar responses.
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Affiliation(s)
| | - Cody T Haun
- Department of Exercise Science, LaGrange College, Lagrange, Georgia
| | | | - Matthew A Romero
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California
| | - Paul A Roberson
- Department of Cellular and Molecular Physiology, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania
| | - Petey W Mumford
- Department of Exercise Science, Lindenwood University, St. Charles, Missouri
| | - C Brooks Mobley
- Department of Physiology, University of Kentucky, Lexington, Kentucky; and
| | | | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, Alabama
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama
- Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, Alabama
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama
- Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, Alabama
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Roberson PA, Mobley CB, Romero MA, Haun CT, Osburn SC, Mumford PW, Vann CG, Greer RA, Ferrando AA, Roberts MD. LAT1 Protein Content Increases Following 12 Weeks of Resistance Exercise Training in Human Skeletal Muscle. Front Nutr 2021; 7:628405. [PMID: 33521042 PMCID: PMC7840583 DOI: 10.3389/fnut.2020.628405] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 12/11/2020] [Indexed: 12/24/2022] Open
Abstract
Introduction: Amino acid transporters are essential for cellular amino acid transport and promoting protein synthesis. While previous literature has demonstrated the association of amino acid transporters and protein synthesis following acute resistance exercise and amino acid supplementation, the chronic effect of resistance exercise and supplementation on amino acid transporters is unknown. The purpose herein was to determine if amino acid transporters and amino acid metabolic enzymes were related to skeletal muscle hypertrophy following resistance exercise training with different nutritional supplementation strategies. Methods: 43 college-aged males were separated into a maltodextrin placebo (PLA, n = 12), leucine (LEU, n = 14), or whey protein concentrate (WPC, n = 17) group and underwent 12 weeks of total-body resistance exercise training. Each group's supplement was standardized for total energy and fat, and LEU and WPC supplements were standardized for total leucine (6 g/d). Skeletal muscle biopsies were obtained prior to training and ~72 h following each subject's last training session. Results: All groups increased type I and II fiber cross-sectional area (fCSA) following training (p < 0.050). LAT1 protein increased following training (p < 0.001) and increased more in PLA than LEU and WPC (p < 0.050). BCKDHα protein increased and ATF4 protein decreased following training (p < 0.001). Immunohistochemistry indicated total LAT1/fiber, but not membrane LAT1/fiber, increased with training (p = 0.003). Utilizing all groups, the change in ATF4 protein, but no other marker, trended to correlate with the change in fCSA (r = 0.314; p = 0.055); however, when regression analysis was used to delineate groups, the change in ATF4 protein best predicted the change in fCSA only in LEU (r 2 = 0.322; p = 0.043). In C2C12 myoblasts, LAT1 protein overexpression caused a paradoxical decrease in protein synthesis levels (p = 0.002) and decrease in BCKDHα protein (p = 0.001). Conclusions: Amino acid transporters and metabolic enzymes are affected by resistance exercise training, but do not appear to dictate muscle fiber hypertrophy. In fact, overexpression of LAT1 in vitro decreased protein synthesis.
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Affiliation(s)
- Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - C Brooks Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Rory A Greer
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Arny A Ferrando
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AK, United States
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Bagley JR, Burghardt KJ, McManus R, Howlett B, Costa PB, Coburn JW, Arevalo JA, Malek MH, Galpin AJ. Epigenetic Responses to Acute Resistance Exercise in Trained vs. Sedentary Men. J Strength Cond Res 2020; 34:1574-1580. [PMID: 32459413 DOI: 10.1519/jsc.0000000000003185] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bagley, JR, Burghardt, KJ, McManus, R, Howlett, B, Costa, PB, Coburn, JW, Arevalo, JA, Malek, MH, and Galpin, AJ. Epigenetic responses to acute resistance exercise in trained vs. sedentary men. J Strength Cond Res 34(6): 1574-1580, 2020-Acute resistance exercise (RE) alters DNA methylation, an epigenetic process that influences gene expression and regulates skeletal muscle adaptation. This aspect of cellular remodeling is poorly understood, especially in resistance-trained (RT) individuals. The study purpose was to examine DNA methylation in response to acute RE in RT and sedentary (SED) young men, specifically targeting genes responsible for metabolic, inflammatory, and hypertrophic muscle adaptations. Vastus lateralis biopsies were performed before (baseline), 30 minutes after, and 4 hours after an acute RE bout (3 × 10 repetitions at 70% 1 repetition maximum [1RM] leg press and leg extension) in 11 RT (mean ± SEM: age = 26.1 ± 1.0 years; body mass = 84.3 ± 0.2 kg; leg press 1RM = 412.6 ± 25.9 kg) and 8 SED (age = 22.9 ± 1.1 years; body mass = 75.6 ± 0.3 kg; leg press 1RM = 164.8 ± 22.5 kg) men. DNA methylation was analyzed through methylation sensitive high-resolution melting using real-time polymerase chain reaction. Separate 2 (group) × 3 (time) repeated-measures analyses of variance and analyses of covariance were performed to examine changes in DNA methylation for each target gene. Results showed that acute RE (a) hypomethylated LINE-1 (measure of global methylation) in RT but not SED, (b) hypermethylated metabolic genes (GPAM and SREBF2) in RT, while lowering SREBF2 methylation in SED, and (c) did not affect methylation of genes associated with inflammation (IL-6 and TNF-α) or hypertrophy (mTOR and AKT1). However, basal IL-6 and TNF-α were lower in SED compared with RT. These findings indicate the same RE stimulus can illicit different epigenetic responses in RT vs. SED men and provides a molecular mechanism underpinning the need for differential training stimuli based on subject training backgrounds.
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Affiliation(s)
- James R Bagley
- Department of Kinesiology, Muscle Physiology Laboratory, San Francisco State University, San Francisco, California
| | - Kyle J Burghardt
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Ryan McManus
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Bradley Howlett
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Pablo B Costa
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Jared W Coburn
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Jose A Arevalo
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Moh H Malek
- Integrative Physiology of Exercise Laboratory, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Andrew J Galpin
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
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Lim C, Shimizu J, Kawano F, Kim HJ, Kim CK. Adaptive responses of histone modifications to resistance exercise in human skeletal muscle. PLoS One 2020; 15:e0231321. [PMID: 32271843 PMCID: PMC7145008 DOI: 10.1371/journal.pone.0231321] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 03/20/2020] [Indexed: 11/19/2022] Open
Abstract
Exercise training causes epigenetic changes in skeletal muscle, although it is unclear how resistance exercise (RE) affects histone modifications. The present study was carried out to investigate the effects of acute RE and RE training on gene expression profiles and histone modifications in human skeletal muscle. Healthy male adults were assigned to acute RE (n = 9, age = 20.5±4.3yr, BMI = 28.0±6.8kg/m2) or RE training (n = 21, age = 23.7±2.5yr, BMI = 24.2±2.7kg/m2) groups. Biopsy samples were obtained from the vastus lateralis muscle before and three hours after a single bout of acute RE, or 3-days after 10 weeks of RE training. RNA sequencing analysis revealed that 153 genes with GO terms including muscle development, stress response, metabolism, cell death, and transcription factor were significantly up-regulated (+291% vs. pre-acute RE) upon acute RE. Expressions of these genes were also greater (+9.6% vs. pre-RE training, p<0.05) in RE trained subjects. Significant up-regulation of acetylated histone 3 (H3) (+235%) and H3 mono-methylated at lysine 4 (+290%) and tri-methylated at lysine 27 (+849%), whereas down-regulation of H3.3 variant (-39%) distributions relative to total H3 were observed at transcriptionally activated loci after acute RE compared to pre-acute RE levels. Interestingly, the distribution of acetylated H3 was found to be up-regulated as compared to the level of total H3 after RE training (+40%, p<0.05). These results indicate that a single bout of RE drastically alters both gene expressions and histone modifications in human skeletal muscle. It is also suggested that enhanced histone acetylation is closely related to up-regulation of gene expressions after RE training.
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Affiliation(s)
- Changhyun Lim
- Department of Kinesiology, McMaster University, Ontario, Canada
| | - Junya Shimizu
- Department of Sports and Health Science, Matsumoto University, Nagano, Japan
| | - Fuminori Kawano
- Department of Sports and Health Science, Matsumoto University, Nagano, Japan
- Graduate School of Health Sciences, Matsumoto University, Nagano, Japan
| | - Hyo Jeong Kim
- Department of Healthy Ageing, Korea National Sport University, Seoul, Korea
| | - Chang Keun Kim
- Exercise and Metabolism Research Center, Zhejiang Normal University, Jinhua, China
- Human Physiology, Korea National Sport University, Seoul, Korea
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Romero MA, Mumford PW, Roberson PA, Osburn SC, Parry HA, Kavazis AN, Gladden LB, Schwartz TS, Baker BA, Toedebusch RG, Childs TE, Booth FW, Roberts MD. Five months of voluntary wheel running downregulates skeletal muscle LINE-1 gene expression in rats. Am J Physiol Cell Physiol 2019; 317:C1313-C1323. [PMID: 31618076 DOI: 10.1152/ajpcell.00301.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transposable elements (TEs) are mobile DNA and constitute approximately half of the human genome. LINE-1 (L1) is the only active autonomous TE in the mammalian genome and has been implicated in a number of diseases as well as aging. We have previously reported that skeletal muscle L1 expression is lower following acute and chronic exercise training in humans. Herein, we used a rodent model of voluntary wheel running to determine whether long-term exercise training affects markers of skeletal muscle L1 regulation. Selectively bred high-running female Wistar rats (n = 11 per group) were either given access to a running wheel (EX) or not (SED) at 5 wk of age, and these conditions were maintained until 27 wk of age. Thereafter, mixed gastrocnemius tissue was harvested and analyzed for L1 mRNA expression and DNA content along with other L1 regulation markers. We observed significantly (P < 0.05) lower L1 mRNA expression, higher L1 DNA methylation, and less L1 DNA in accessible chromatin regions in EX versus SED rats. We followed these experiments with 3-h in vitro drug treatments in L6 myotubes to mimic transient exercise-specific signaling events. The AMP-activated protein kinase (AMPK) agonist 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR; 4 mM) significantly decreased L1 mRNA expression in L6 myotubes. However, this effect was not facilitated through increased L1 DNA methylation. Collectively, these data suggest that long-term voluntary wheel running downregulates skeletal muscle L1 mRNA, and this may occur through chromatin modifications. Enhanced AMPK signaling with repetitive exercise bouts may also decrease L1 mRNA expression, although the mechanism of action remains unknown.
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Affiliation(s)
| | | | | | | | - Hailey A Parry
- School of Kinesiology, Auburn University, Auburn, Alabama
| | | | | | - Tonia S Schwartz
- Department of Biological Sciences, Auburn University, Auburn, Alabama
| | - Brent A Baker
- National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia
| | - Ryan G Toedebusch
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Thomas E Childs
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, Alabama
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Roberson PA, Romero MA, Osburn SC, Mumford PW, Vann CG, Fox CD, McCullough DJ, Brown MD, Roberts MD. Skeletal muscle LINE-1 ORF1 mRNA is higher in older humans but decreases with endurance exercise and is negatively associated with higher physical activity. J Appl Physiol (1985) 2019; 127:895-904. [PMID: 31369326 DOI: 10.1152/japplphysiol.00352.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The long interspersed nuclear element-1 (L1) is a retrotransposon that constitutes 17% of the human genome and is associated with various diseases and aging. Estimates suggest that ~100 L1 copies are capable of copying and pasting into other regions of the genome. Herein, we examined if skeletal muscle L1 markers are affected by aging or an acute bout of cycling exercise in humans. Apparently healthy younger (23 ± 3 y, n = 15) and older participants (58 ± 8 y, n = 15) donated a vastus lateralis biopsy before 1 h of cycling exercise (PRE) at ~70% of heart rate reserve. Second (2 h) and third (8 h) postexercise muscle biopsies were also obtained. L1 DNA and mRNA expression were quantified using three primer sets [5' untranslated region (UTR), L1.3, and ORF1]. 5'UTR and L1.3 DNA methylation as well as ORF1 protein expression were also quantified. PRE 5'UTR, ORF1, or L1.3 DNA were not different between age groups (P > 0.05). ORF1 mRNA was greater in older versus younger participants (P = 0.014), and cycling lowered this marker at 2 h versus PRE (P = 0.027). 5'UTR and L1.3 DNA methylation were higher in younger versus older participants (P < 0.05). Accelerometry data collected during a 2-wk period before the exercise bout indicated higher moderate-to-vigorous physical activity (MVPA) levels per day was associated with lower PRE ORF1 mRNA in all participants (r = -0.398, P = 0.032). In summary, skeletal muscle ORF1 mRNA is higher in older apparently healthy humans, which may be related to lower DNA methylation patterns. ORF1 mRNA is also reduced with endurance exercise and is negatively associated with higher daily MVPA levels.NEW & NOTEWORTHY The long interspersed nuclear element-1 (L1) gene is highly abundant in the genome and encodes for an autonomous retrotransposon, which is capable of copying and pasting itself into other portions of the genome. This is the first study in humans to demonstrate that certain aspects of skeletal muscle L1 activity are altered with aging. Additionally, this is the first study in humans to demonstrate that L1 ORF1 mRNA levels decrease after a bout of endurance exercise, regardless of age.
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Affiliation(s)
| | | | | | | | | | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, Alabama
| | - Danielle J McCullough
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, Alabama
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, Alabama
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