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Stec MJ, Kelly NA, Many GM, Windham ST, Tuggle SC, Bamman MM. Ribosome biogenesis may augment resistance training-induced myofiber hypertrophy and is required for myotube growth in vitro. Am J Physiol Endocrinol Metab 2016; 310:E652-E661. [PMID: 26860985 PMCID: PMC4835943 DOI: 10.1152/ajpendo.00486.2015] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 02/03/2016] [Indexed: 12/22/2022]
Abstract
Resistance exercise training (RT) is the most effective method for increasing skeletal muscle mass in older adults; however, the amount of RT-induced muscle growth is highly variable between individuals. Recent evidence from our laboratory and others suggests ribosome biogenesis may be an important factor regulating RT-induced hypertrophy, and we hypothesized that the extent of hypertrophy is at least partly regulated by the amount of RT-induced ribosome biogenesis. To examine this, 42 older adults underwent 4 wk of RT aimed at inducing hypertrophy of the knee extensors (e.g., 2 sets of squat, leg press, and knee extension, 10-12 repetition maximums, 3 days/wk), and vastus lateralis muscle biopsies were performed pre- and post-RT. Post hoc K-means cluster analysis revealed distinct differences in type II myofiber hypertrophy among subjects. The percent change in type II myofiber size in nonresponders (Non; n = 17) was -7%, moderate responders (Mod; n = 19) +22%, and extreme responders (Xtr; n = 6) +83%. Total muscle RNA increased only in Mod (+9%, P < 0.08) and Xtr (+26%, P < 0.01), and only Xtr increased rRNA content (+40%, P < 0.05) and myonuclei/type II fiber (+32%, P < 0.01). Additionally, Mod and Xtr had a greater increase in c-Myc protein levels compared with Non (e.g., approximately +350 and +250% vs. +50%, respectively, P < 0.05). In vitro studies showed that growth factor-induced human myotube hypertrophy is abolished when rRNA synthesis is knocked down using the Pol I-specific inhibitor CX-5461. Overall, these data implicate ribosome biogenesis as a key process regulating the extent of RT-induced myofiber hypertrophy in older adults.
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Affiliation(s)
- Michael J Stec
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Neil A Kelly
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Gina M Many
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Samuel T Windham
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - S Craig Tuggle
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Marcas M Bamman
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama;
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Birmingham, Alabama
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Porter C, Hurren NM, Cotter MV, Bhattarai N, Reidy PT, Dillon EL, Durham WJ, Tuvdendorj D, Sheffield-Moore M, Volpi E, Sidossis LS, Rasmussen BB, Børsheim E. Mitochondrial respiratory capacity and coupling control decline with age in human skeletal muscle. Am J Physiol Endocrinol Metab 2015; 309:E224-32. [PMID: 26037248 PMCID: PMC4525111 DOI: 10.1152/ajpendo.00125.2015] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 06/01/2015] [Indexed: 11/22/2022]
Abstract
Mitochondrial health is critical to physiological function, particularly in tissues with high ATP turnover, such as striated muscle. It has been postulated that derangements in skeletal muscle mitochondrial function contribute to impaired physical function in older adults. Here, we determined mitochondrial respiratory capacity and coupling control in skeletal muscle biopsies obtained from young and older adults. Twenty-four young (28 ± 7 yr) and thirty-one older (62 ± 8 yr) adults were studied. Mitochondrial respiration was determined in permeabilized myofibers from the vastus lateralis after the addition of substrates oligomycin and CCCP. Thereafter, mitochondrial coupling control was calculated. Maximal coupled respiration (respiration linked to ATP production) was lower in muscle from older vs. young subjects (P < 0.01), as was maximal uncoupled respiration (P = 0.06). Coupling control in response to the ATP synthase inhibitor oligomycin was lower in older adults (P < 0.05), as was the mitochondria flux control ratio, coupled respiration normalized to maximal uncoupled respiration (P < 0.05). Calculation of respiratory function revealed lower respiration linked to ATP production (P < 0.001) and greater reserve respiration (P < 0.01); i.e., respiratory capacity not used for phosphorylation in muscle from older adults. We conclude that skeletal muscle mitochondrial respiratory capacity and coupling control decline with age. Lower respiratory capacity and coupling efficiency result in a reduced capacity for ATP production in skeletal muscle of older adults.
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Affiliation(s)
- Craig Porter
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas; Shriners Hospitals for Children, Galveston, Texas;
| | - Nicholas M Hurren
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas; Shriners Hospitals for Children, Galveston, Texas; Departments of Pediatrics and Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Arkansas Children's Hospital Research Institute, and Arkansas Children's Nutrition Center, Little Rock, Arkansas
| | - Matthew V Cotter
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas; Departments of Pediatrics and Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Arkansas Children's Hospital Research Institute, and Arkansas Children's Nutrition Center, Little Rock, Arkansas
| | - Nisha Bhattarai
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas; Shriners Hospitals for Children, Galveston, Texas
| | - Paul T Reidy
- Department of Rehabilitation Sciences, University of Texas Medical Branch, Galveston, Texas; and
| | - Edgar L Dillon
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - William J Durham
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Demidmaa Tuvdendorj
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | | | - Elena Volpi
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Labros S Sidossis
- Shriners Hospitals for Children, Galveston, Texas; Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Blake B Rasmussen
- Department of Rehabilitation Sciences, University of Texas Medical Branch, Galveston, Texas; and
| | - Elisabet Børsheim
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas; Shriners Hospitals for Children, Galveston, Texas; Departments of Pediatrics and Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Arkansas Children's Hospital Research Institute, and Arkansas Children's Nutrition Center, Little Rock, Arkansas
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Smith HK, Merry TL. Voluntary resistance wheel exercise during post-natal growth in rats enhances skeletal muscle satellite cell and myonuclear content at adulthood. Acta Physiol (Oxf) 2012; 204:393-402. [PMID: 21854550 DOI: 10.1111/j.1748-1716.2011.02350.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
AIM To determine whether voluntary free wheel (FW) or resistance wheel (RW) exercise or reduced muscle activity would influence maturational increases in muscle mass and the number of satellite cells (SCs) and myonuclei (MN) accrued by adulthood. METHODS Hind limb muscles of male rats housed with, or without, FWs from 4 to 5, 7 or 10 weeks of age, and rats housed with RWs from 4 to 10 week of age, were evaluated. To assess the effect of reduced muscle activity, gastrocnemius muscles of 4-week-old rats were injected with botulinum toxin (Btx) and collected at 7 weeks of age. Muscle fibre size and the frequency of Pax7-positive SCs and MN were determined in 7- and 10-week-old muscles via immunohistochemical methods. RESULTS Free wheel exercise enhanced muscle growth and the frequency of SCs in the medial gastrocnemius (MG) (threefold) and vastus lateralis (VL) (twofold) of rats at 10 week of age. Resistance wheel exercise increased the number of SCs and MN (22-30%), with more muscle fibre nuclei being associated with larger fibre size, in the soleus, MG and VL muscles. Btx impaired the normal increases in muscle fibre size and the accrual of MN but not SCs. CONCLUSION A greater volume of exercise during maturational growth was important for enhancing SC numbers, whereas their conversion to MN required higher-intensity exercise. The enhanced muscle fibre nuclear populations may influence the capacity of the muscle to adapt to exercise, injury or disuse in later adulthood.
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Affiliation(s)
- H K Smith
- Department of Sport and Exercise Science, University of Auckland, New Zealand.
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Manini TM, Vincent KR, Leeuwenburgh CL, Lees HA, Kavazis AN, Borst SE, Clark BC. Myogenic and proteolytic mRNA expression following blood flow restricted exercise. Acta Physiol (Oxf) 2011; 201:255-63. [PMID: 20653608 DOI: 10.1111/j.1748-1716.2010.02172.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM Resistance exercise performed at low loads (20-30% of maximal strength) with blood flow restriction (BFR) acutely increases protein synthesis and induces hypertrophy when performed chronically. We investigated myogenic and proteolytic mRNA expression 8 h following an acute bout of knee extension exercise. METHODS Fifteen subjects (22.8 ± 3.7 years, eight men and seven women) were randomized to two exercise conditions: BFR or control exercise. All participants performed four sets of exercise (30, 15, 15 and 15 repetitions) at 20% of maximal strength. Persons in the BFR group had a cuff placed on the upper thigh inflated to 1.5 times brachial systolic blood pressure (cuff pressure range: 135-186 mmHg). Muscle biopsies from the vastus lateralis were excised 24 h before and 8 h following the exercise. RESULTS RT-PCR analysis demonstrated no change in myogenic gene expression (insulin-like growth factor-1, MyoD, myogenin, myostatin - a negative regulator) with either exercise condition (P > 0.123). However, BFR exercise downregulated mRNA expression in transcripts associated with proteolytic pathways (FOXO3A, Atrogin-1 and MuRF-1) with no change in the control exercise condition. Specifically, median mRNA expression of FOXO3A decreased by 1.92-fold (P = 0.01), Atrogin-1 by 2.10-fold (P = 0.01) and MuRF-1 by 2.44-fold (P = 0.01). CONCLUSION These data are consistent with the downregulation of proteolytic transcripts observed following high-load resistance exercise. In summary, myogenic genes are unchanged and proteolytic genes associated with muscle remodelling are reduced 8 h following low-load BFR exercise.
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Affiliation(s)
- T M Manini
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL 32611-0107, USA.
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Abstract
Biglycan is an extracellular ligand for the dystrophin-associated protein complex (DAPC) that is upregulated in both dystrophic and regenerating muscle. Biglycan also binds to collagen VI, mutations of which cause a congenital muscular dystrophy (Ullrich's; UCMD) that is also characterized by connective tissue abnormalities. The expression of biglycan in early development and postnatal ages has not been well characterized. Here we show that biglycan transcript levels peak at approximately 21 weeks' gestation in human fetal muscle. Immunocytochemical analysis of developing mouse muscle shows that biglycan can be detected in muscle as early as embryonic day (E)16 and is most abundant between postnatal day (P)1 and P7. Biglycan is also highly expressed in developing tendon, with maximal levels observed at E16-18. This robust tendon expression is correlated with a sharp peak in biglycan transcript levels in the hindlimb. Finally, at E18 collagen VI colocalizes with biglycan in tendon. These results suggest that biglycan has a particularly important function during muscle and connective tissue development. Moreover, biglycan may play a role in the pathogenesis of collagen VI-associated congenital muscular dystrophies.
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Affiliation(s)
- Beatrice E Lechner
- Department of Pediatrics, Women and Infants Hospital, Providence, Rhode Island 02912, USA
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