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Grima-Terrén M, Campanario S, Ramírez-Pardo I, Cisneros A, Hong X, Perdiguero E, Serrano AL, Isern J, Muñoz-Cánoves P. Muscle aging and sarcopenia: The pathology, etiology, and most promising therapeutic targets. Mol Aspects Med 2024; 100:101319. [PMID: 39312874 DOI: 10.1016/j.mam.2024.101319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 09/13/2024] [Accepted: 09/16/2024] [Indexed: 09/25/2024]
Abstract
Sarcopenia is a progressive muscle wasting disorder that severely impacts the quality of life of elderly individuals. Although the natural aging process primarily causes sarcopenia, it can develop in response to other conditions. Because muscle function is influenced by numerous changes that occur with age, the etiology of sarcopenia remains unclear. However, recent characterizations of the aging muscle transcriptional landscape, signaling pathway disruptions, fiber and extracellular matrix compositions, systemic metabolomic and inflammatory responses, mitochondrial function, and neurological inputs offer insights and hope for future treatments. This review will discuss age-related changes in healthy muscle and our current understanding of how this can deteriorate into sarcopenia. As our elderly population continues to grow, we must understand sarcopenia and find treatments that allow individuals to maintain independence and dignity throughout an extended lifespan.
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Affiliation(s)
- Mercedes Grima-Terrén
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA; Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain
| | - Silvia Campanario
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA; Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain
| | - Ignacio Ramírez-Pardo
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA; Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain
| | - Andrés Cisneros
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA; Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain
| | - Xiaotong Hong
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA
| | | | - Antonio L Serrano
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA
| | - Joan Isern
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA
| | - Pura Muñoz-Cánoves
- Altos Labs, San Diego Institute of Science, San Diego, CA, 92121, USA; Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain.
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Jahanian S, Pareja-Cajiao M, Gransee HM, Sieck GC, Mantilla CB. Autophagy markers LC3 and p62 in aging lumbar motor neurons. Exp Gerontol 2024; 194:112483. [PMID: 38885913 PMCID: PMC11326290 DOI: 10.1016/j.exger.2024.112483] [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] [Received: 04/06/2024] [Revised: 06/03/2024] [Accepted: 06/06/2024] [Indexed: 06/20/2024]
Abstract
Autophagy is a ubiquitous process through which damaged cytoplasmic structures are recycled and degraded within cells. Aging can affect autophagy regulation in different steps leading to the accumulation of damaged organelles and proteins, which can contribute to cell dysfunction and death. Motor neuron (MN) loss and sarcopenia are prominent features of neuromuscular aging. Previous studies on phrenic MNs showed increased levels of the autophagy proteins LC3 and p62 in 24 month compared to 6 month old mice, consistent with the onset of diaphragm muscle sarcopenia. In the present study, we hypothesized that aging leads to increased expression of the autophagy markers LC3 and p62 in single lumbar MNs. Expression of LC3 and p62 in lumbar MNs (spinal levels L1-L6) was assessed using immunofluorescence and confocal imaging of male and female mice at 6, 18 and 24 months of age, reflecting 100 %, 90 % and 75 % survival, respectively. A mixed linear model with animal as a random effect was used to compare relative LC3 and p62 expression in choline acetyl transferase-positive MNs across age groups. Expression of LC3 and p62 decreased in the white matter of the lumbar spinal cord with aging, with ~29 % decrease in LC3 and ~ 7 % decrease in p62 expression at 24 months of age compared to 6 months of age. There was no change in LC3 or p62 expression in the gray matter with age. LC3 expression in MNs relative to white matter increased significantly with age, with 150 % increase at 24 months of age compared to 6 months of age. Similarly, p62 expression in MNs relative to white matter increased significantly with age, with ~14 % increase at 24 months of age compared to 6 months of age. No effect of sex or MN pool was observed in LC3 and p62 expression in MNs. Overall, these data suggest autophagy impairment during elongation (increased LC3) and degradation (increased p62) phases with aging in lumbar MNs.
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Affiliation(s)
- Sepideh Jahanian
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Miguel Pareja-Cajiao
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Heather M Gransee
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Gary C Sieck
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Department of Physiology & Biomedical Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Carlos B Mantilla
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Department of Physiology & Biomedical Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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Wang ZM, Messi ML, Rodrigues ACZ, Delbono O. Skeletal muscle sympathetic denervation disrupts the neuromuscular junction postterminal organization: A single-cell quantitative approach. Mol Cell Neurosci 2022; 120:103730. [PMID: 35489637 PMCID: PMC9793435 DOI: 10.1016/j.mcn.2022.103730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/28/2022] [Accepted: 04/12/2022] [Indexed: 12/30/2022] Open
Abstract
The sympathetic nervous system (SNS) regulates skeletal muscle motor innervation and stabilizes the NMJ in health, disease and aging. Previous studies using both chemical (6-hydroxydopamine, 6-OHDA) and microsurgically-induced sympathetic denervation examined the NMJ organization and transmission in the mouse; however, a detailed quantification of the postterminal on larger hindlimb muscles involved in gait mechanics and posture is lacking. The purpose of this study was to determine whether targets of the sympathetic neuron (SN) exhibiting different intrinsic composition such as the fast-twitch extensor digitorum longus (EDL) and the slow-twitch soleus muscles differ in their response to SN deprivation, and to develop a strategy to accurately quantify the impact of sympathectomy on the NMJ postterminal including those fibers located deeper in the muscle. This approach included muscle fixed ex vivo or through transcardial perfusion in mice treated with 6-OHDA or control ascorbic acid. We measured NMJ postterminal mean terminal total area, number of postterminal fragments, mean fragment area, and mean distance between fragments in free-floating alpha-bungarotoxin-stained in 1038 isolated muscle fibers. We found that muscle fiber sympathetic innervation plays a crucial role in the structural organization of the motorneuron-myofiber synapse postterminal and its deprivation leads to AChR cluster dispersion or shrinking as described in various neuromuscular diseases and aging.
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Affiliation(s)
- Zhong-Min Wang
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America
| | - María Laura Messi
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America
| | - Anna Carolina Zaia Rodrigues
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America,the Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America
| | - Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America,the Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America,Sticht Center for Healthy Aging and Alzheimer’s Prevention, Wake Forest School of Medicine, Winston-Salem, NC 27157, United States of America,Corresponding author at: Wake Forest School of Medicine, Department of Internal Medicine, Gerontology, Medical Center Boulevard, Winston-Salem, NC 27157, United States of America. (O. Delbono)
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Rodrigues ACZ, Messi ML, Wang ZM, Bonilla HJ, Freeman WM, Delbono O. Long-term, induced expression of Hand2 in peripheral sympathetic neurons ameliorates sarcopenia in geriatric mice. J Cachexia Sarcopenia Muscle 2021; 12:1908-1924. [PMID: 34546662 PMCID: PMC8718059 DOI: 10.1002/jcsm.12790] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 07/20/2021] [Accepted: 08/06/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The discovery of adrenoceptors, which mediate the effects of the sympathetic nervous system neurotransmitter norepinephrine on specific tissues, sparked the development of sympathomimetics that have profound influence on skeletal muscle mass. However, chronic administration has serious side effects that preclude their use for muscle-wasting conditions such as sarcopenia, the age-dependent decline in muscle mass, force, and power. Devising interventions that can adjust neurotransmitter release to changing physiological demands will require understanding how the sympathetic nervous system affects muscle motor innervation and muscle mass, which will prevent sarcopenia-associated impaired mobility, falls, institutionalization, co-morbidity, and premature death. Here, we tested the hypothesis that prolonged heart and neural crest derivative 2 (Hand2) expression in peripheral sympathetic neurons (SNs) ameliorates sympathetic muscle denervation, motor denervation, and sarcopenia in geriatric mice. METHODS We delivered either a viral vector encoding the transcription factor Hand2 or an empty vector (EV) driven to SNs by the PRSx8 promoter by injecting the saphenous vein in 16-month-old C57BL/6 mice that were sacrificed 10-11 months later. Studies relied on sympathetic and muscle immunohistochemistry analysed by confocal microscopy, nerve and muscle protein expression assessed by immunoblots, nerve-evoked and muscle-evoked maximal muscle contraction force, extensor digitorum longus (EDL) muscle RNA sequencing, SN real-time PCR, and tests of physical performance using an inverted-cling grip test and in an open-arena setting. RESULTS Examining the mice 10-11 months later, we found that inducing Hand2 expression in peripheral SNs preserved (i) the number of neurons (EV: 0.32 ± 0.03/μm2 , n = 6; Hand2: 0.92 ± 0.08/μm2 , n = 7; P < 0.0001) and size (EV: 279 ± 18 μm2 , n = 6; Hand2: 396 ± 18 μm2 , n = 7; P < 0.0001); (ii) lumbricalis muscle sympathetic innervation (EV: 1.4 ± 1.5 μm/μm2 , n = 5; Hand2: 12 ± 1.8 μm/μm2 , n = 5; P < 0.001); (iii) tibialis anterior, gastrocnemius, EDL, and soleus muscles weight and whole-body strength (EV: 48 ± 6.4 s, n = 6; Hand2: 102 ± 6.8 s, n = 6; P < 0.001); (iv) EDL type IIb, IIx, and II/IIx and soleus type I, IIa, IIx, IIa/IIx, and IIb/IIx myofibre cross-sectional area; (v) nerve-evoked (EV: 16 ± 2.7 mN; Hand2: 30 ± 4.4 mN; P < 0.001) and muscle-evoked (EV: 24 ± 3.8 mN, n = 5; Hand2: 38 ± 3.0 mN, n = 8; P < 0.001) muscle force by 150 Hz-3 s pulses; and (vi) motor innervation assessed by measuring presynaptic/postsynaptic neuromuscular junction area overlay. CONCLUSIONS Preserving Hand2 expression in SNs from middle-aged to very old mice attenuates decreases in muscle mass and force by (i) maintaining skeletal muscle sympathetic and motor innervation, (ii) improving membrane and total acetylcholine receptor stability and nerve-evoked and muscle-evoked muscle contraction, (iii) preventing the elevation of inflammation and myofibrillar protein degradation markers, and (iv) increasing muscle autophagy.
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Affiliation(s)
- Anna Carolina Zaia Rodrigues
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,The Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - María Laura Messi
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Zhong-Min Wang
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Henry Jacob Bonilla
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | - Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,The Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC, USA.,The Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Rasmussen M, Jin JP. Troponin Variants as Markers of Skeletal Muscle Health and Diseases. Front Physiol 2021; 12:747214. [PMID: 34733179 PMCID: PMC8559874 DOI: 10.3389/fphys.2021.747214] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 09/01/2021] [Indexed: 12/21/2022] Open
Abstract
Ca2 +-regulated contractility is a key determinant of the quality of muscles. The sarcomeric myofilament proteins are essential players in the contraction of striated muscles. The troponin complex in the actin thin filaments plays a central role in the Ca2+-regulation of muscle contraction and relaxation. Among the three subunits of troponin, the Ca2+-binding subunit troponin C (TnC) is a member of the calmodulin super family whereas troponin I (TnI, the inhibitory subunit) and troponin T (TnT, the tropomyosin-binding and thin filament anchoring subunit) are striated muscle-specific regulatory proteins. Muscle type-specific isoforms of troponin subunits are expressed in fast and slow twitch fibers and are regulated during development and aging, and in adaptation to exercise or disuse. TnT also evolved with various alternative splice forms as an added capacity of muscle functional diversity. Mutations of troponin subunits cause myopathies. Owing to their physiological and pathological importance, troponin variants can be used as specific markers to define muscle quality. In this focused review, we will explore the use of troponin variants as markers for the fiber contents, developmental and differentiation states, contractile functions, and physiological or pathophysiological adaptations of skeletal muscle. As protein structure defines function, profile of troponin variants illustrates how changes at the myofilament level confer functional qualities at the fiber level. Moreover, understanding of the role of troponin modifications and mutants in determining muscle contractility in age-related decline of muscle function and in myopathies informs an approach to improve human health.
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Affiliation(s)
- Monica Rasmussen
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States
| | - Jian-Ping Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, United States
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6
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The emerging role of the sympathetic nervous system in skeletal muscle motor innervation and sarcopenia. Ageing Res Rev 2021; 67:101305. [PMID: 33610815 DOI: 10.1016/j.arr.2021.101305] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/06/2021] [Accepted: 02/15/2021] [Indexed: 12/30/2022]
Abstract
Examining neural etiologic factors'role in the decline of neuromuscular function with aging is essential to our understanding of the mechanisms underlying sarcopenia, the age-dependent decline in muscle mass, force and power. Innervation of the skeletal muscle by both motor and sympathetic axons has been established, igniting interest in determining how the sympathetic nervous system (SNS) affect skeletal muscle composition and function throughout the lifetime. Selective expression of the heart and neural crest derivative 2 gene in peripheral SNs increases muscle mass and force regulating skeletal muscle sympathetic and motor innervation; improving acetylcholine receptor stability and NMJ transmission; preventing inflammation and myofibrillar protein degradation; increasing autophagy; and probably enhancing protein synthesis. Elucidating the role of central SNs will help to define the coordinated response of the visceral and neuromuscular system to physiological and pathological challenges across ages. This review discusses the following questions: (1) Does the SNS regulate skeletal muscle motor innervation? (2) Does the SNS regulate presynaptic and postsynaptic neuromuscular junction (NMJ) structure and function? (3) Does sympathetic neuron (SN) regulation of NMJ transmission decline with aging? (4) Does maintenance of SNs attenuate aging sarcopenia? and (5) Do central SN group relays influence sympathetic and motor muscle innervation?
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7
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Carreras D, Martinez-Moreno R, Pinsach-Abuin M, Santafe MM, Gomà P, Brugada R, Scornik FS, Pérez GJ, Pagans S. Epigenetic Changes Governing Scn5a Expression in Denervated Skeletal Muscle. Int J Mol Sci 2021; 22:ijms22052755. [PMID: 33803193 PMCID: PMC7963191 DOI: 10.3390/ijms22052755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 02/06/2023] Open
Abstract
The SCN5A gene encodes the α-subunit of the voltage-gated cardiac sodium channel (NaV1.5), a key player in cardiac action potential depolarization. Genetic variants in protein-coding regions of the human SCN5A have been largely associated with inherited cardiac arrhythmias. Increasing evidence also suggests that aberrant expression of the SCN5A gene could increase susceptibility to arrhythmogenic diseases, but the mechanisms governing SCN5A expression are not yet well understood. To gain insights into the molecular basis of SCN5A gene regulation, we used rat gastrocnemius muscle four days following denervation, a process well known to stimulate Scn5a expression. Our results show that denervation of rat skeletal muscle induces the expression of the adult cardiac Scn5a isoform. RNA-seq experiments reveal that denervation leads to significant changes in the transcriptome, with Scn5a amongst the fifty top upregulated genes. Consistent with this increase in expression, ChIP-qPCR assays show enrichment of H3K27ac and H3K4me3 and binding of the transcription factor Gata4 near the Scn5a promoter region. Also, Gata4 mRNA levels are significantly induced upon denervation. Genome-wide analysis of H3K27ac by ChIP-seq suggest that a super enhancer recently described to regulate Scn5a in cardiac tissue is activated in response to denervation. Altogether, our experiments reveal that similar mechanisms regulate the expression of Scn5a in denervated muscle and cardiac tissue, suggesting a conserved pathway for SCN5A expression among striated muscles.
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Affiliation(s)
- David Carreras
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
| | - Rebecca Martinez-Moreno
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
| | - Mel·lina Pinsach-Abuin
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
| | - Manel M. Santafe
- Unit of Histology and Neurobiology, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Rovira i Virgili University, 43003 Reus, Spain;
| | - Pol Gomà
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
| | - Ramon Brugada
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), 21005 Madrid, Spain
- Hospital Josep Trueta, 17007 Girona, Spain
| | - Fabiana S. Scornik
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), 21005 Madrid, Spain
- Correspondence: (F.S.S.); (G.J.P.); (S.P.)
| | - Guillermo J. Pérez
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), 21005 Madrid, Spain
- Correspondence: (F.S.S.); (G.J.P.); (S.P.)
| | - Sara Pagans
- Cardiovascular Genetics Center, Biomedical Research Institute of Girona, 17190 Salt, Spain; (D.C.); (R.M.-M.); (M.P.-A.); (P.G.); (R.B.)
- Department of Medical Sciences, Universitat de Girona, 17003 Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), 21005 Madrid, Spain
- Correspondence: (F.S.S.); (G.J.P.); (S.P.)
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Rodrigues ACZ, Wang ZM, Messi ML, Bonilla HJ, Liu L, Freeman WM, Delbono O. Heart and neural crest derivative 2-induced preservation of sympathetic neurons attenuates sarcopenia with aging. J Cachexia Sarcopenia Muscle 2021; 12:91-108. [PMID: 33258279 PMCID: PMC7890150 DOI: 10.1002/jcsm.12644] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 10/02/2020] [Accepted: 10/12/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Sarcopenia, or age-dependent decline in muscle force and power, impairs mobility, increasing the risk of falls, institutionalization, co-morbidity, and premature death. The discovery of adrenoceptors, which mediate the effects of the sympathetic nervous system (SNS) neurotransmitter norepinephrine on specific tissues, sparked the development of sympathomimetics that have profound influence on skeletal muscle mass. However, chronic administration has serious side effects that preclude their use for muscle-wasting conditions. Interventions that can adjust neurotransmitter release to changing physiological demands depend on understanding how the SNS affects neuromuscular transmission, muscle motor innervation, and muscle mass. METHODS We examined age-dependent expression of the heart and neural crest derivative 2 (Hand2), a critical transcription factor for SN maintenance, and we tested the possibility that inducing its expression exclusively in sympathetic neurons (SN) will prevent (i) motor denervation, (ii) impaired neuromuscular junction (NMJ) transmission, and (iii) loss of muscle mass and function in old mice. To test this hypothesis, we delivered a viral vector carrying Hand2 expression or an empty vector exclusively in SNs by vein injection in 16-month-old C57BL/6 mice that were sacrificed 6 months later. Techniques include RNA-sequencing, real-time PCR, genomic DNA methylation, viral vector construct, tissue immunohistochemistry, immunoblot, confocal microscopy, electrophysiology, and in vivo mouse physical performance. RESULTS Hand2 expression declines throughout life, but inducing its expression increased (i) the number and size of SNs, (ii) muscle sympathetic innervation, (iii) muscle weight and force and whole-body strength, (iv) myofiber size but not muscle fibre-type composition, (v) NMJ transmission and nerve-evoked muscle force, and (vi) motor innervation in old mice. Additionally, the SN controls a set of genes to reduce inflammation and to promote transcription factor activity, cell signalling, and synapse in the skeletal muscle. Hand2 DNA methylation may contribute, at least partially, to gene silencing. CONCLUSIONS Selective expression of Hand2 in the mouse SNs from middle age through old age increases muscle mass and force by (i) regulating skeletal muscle sympathetic and motor innervation; (ii) improving acetylcholine receptor stability and NMJ transmission; (iii) preventing inflammation and myofibrillar protein degradation; (iv) increasing autophagy; and (v) probably enhancing protein synthesis.
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Affiliation(s)
- Anna Carolina Zaia Rodrigues
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Zhong-Min Wang
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - María Laura Messi
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Henry Jacob Bonilla
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Liang Liu
- Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | - Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
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9
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Anagnostou ME, Hepple RT. Mitochondrial Mechanisms of Neuromuscular Junction Degeneration with Aging. Cells 2020; 9:cells9010197. [PMID: 31941062 PMCID: PMC7016881 DOI: 10.3390/cells9010197] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle deteriorates with aging, contributing to physical frailty, poor health outcomes, and increased risk of mortality. Denervation is a major driver of changes in aging muscle. This occurs through transient denervation-reinnervation events throughout the aging process that remodel the spatial domain of motor units and alter fiber type. In advanced age, reinnervation wanes, leading to persistent denervation that accelerates muscle atrophy and impaired muscle contractility. Alterations in the muscle fibers and motoneurons are both likely involved in driving denervation through destabilization of the neuromuscular junction. In this respect, mitochondria are implicated in aging and age-related neurodegenerative disorders, and are also likely key to aging muscle changes through their direct effects in muscle fibers and through secondary effects mediated by mitochondrial impairments in motoneurons. Indeed, the large abundance of mitochondria in muscle fibers and motoneurons, that are further concentrated on both sides of the neuromuscular junction, likely renders the neuromuscular junction especially vulnerable to age-related mitochondrial dysfunction. Manifestations of mitochondrial dysfunction with aging include impaired respiratory function, elevated reactive oxygen species production, and increased susceptibility to permeability transition, contributing to reduced ATP generating capacity, oxidative damage, and apoptotic signaling, respectively. Using this framework, in this review we summarize our current knowledge, and relevant gaps, concerning the potential impact of mitochondrial impairment on the aging neuromuscular junction, and the mechanisms involved.
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10
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Neuromuscular junction transmission failure is a late phenotype in aging mice. Neurobiol Aging 2019; 86:182-190. [PMID: 31866157 DOI: 10.1016/j.neurobiolaging.2019.10.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/12/2019] [Accepted: 10/29/2019] [Indexed: 12/23/2022]
Abstract
Neurodegeneration has increasingly been considered an important factor in the pathogenesis of sarcopenia or age-related loss of muscle mass and strength. Experiments were designed to investigate the fidelity of neuromuscular junction (NMJ) transmission across the lifespan in hindlimb muscles of male and female C57BL/6J mice (at 12, 20, 24, 27, and 29 months of age). Single-fiber electromyography recordings demonstrated abrupt onset of NMJ transmission failure at 27 months of age. Failed NMJ transmission was a later onset phenotype as compared with other assessments of motor unit numbers, muscle contractility, and frailty which showed alterations at 20 months of age. Ex vivo NMJ recordings demonstrated no reduction of endplate current amplitude in support of reduced muscle fiber excitability as the cause of failed NMJ transmission in aged mice. Improved understanding of age-related neurodegeneration will likely have important implications in designing novel therapeutic interventions specific for different stages of sarcopenia. Our findings suggest reduced muscle excitability may be a potential therapeutic target for improvement of physical function in older adults.
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11
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Ubaida-Mohien C, Lyashkov A, Gonzalez-Freire M, Tharakan R, Shardell M, Moaddel R, Semba RD, Chia CW, Gorospe M, Sen R, Ferrucci L. Discovery proteomics in aging human skeletal muscle finds change in spliceosome, immunity, proteostasis and mitochondria. eLife 2019; 8:49874. [PMID: 31642809 PMCID: PMC6810669 DOI: 10.7554/elife.49874] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 09/16/2019] [Indexed: 12/19/2022] Open
Abstract
A decline of skeletal muscle strength with aging is a primary cause of mobility loss and frailty in older persons, but the molecular mechanisms of such decline are not understood. Here, we performed quantitative proteomic analysis from skeletal muscle collected from 58 healthy persons aged 20 to 87 years. In muscle from older persons, ribosomal proteins and proteins related to energetic metabolism, including those related to the TCA cycle, mitochondria respiration, and glycolysis, were underrepresented, while proteins implicated in innate and adaptive immunity, proteostasis, and alternative splicing were overrepresented. Consistent with reports in animal models, older human muscle was characterized by deranged energetic metabolism, a pro-inflammatory environment and increased proteolysis. Changes in alternative splicing with aging were confirmed by RNA-seq analysis. We propose that changes in the splicing machinery enables muscle cells to respond to a rise in damage with aging. As humans age, their muscles become weaker, making it increasingly harder for them to move, a condition known as sarcopenia. Analyzing old muscles in other animals revealed that they produce energy inefficiently, they destroy more proteins than younger muscles, and they have high levels of molecules that cause inflammation. These characteristics may be involved in causing muscle weakness. Proteomics is the study of proteins, the molecules that play many roles in keeping the body working: for example, they accelerate chemical reactions, participate in copying DNA and help cells respond to stimuli. Using proteomics, it is possible to examine a large number of the different proteins in a tissue, which can provide information about the state of that tissue. Ubaida-Mohien et al. used this approach to answer the question of why muscles become weaker with age. First, they analyzed the levels of all the proteins found in skeletal muscle collected from 58 healthy volunteers between 20 and 87 years of age. This revealed that the muscles of older people have fewer copies of the proteins that make up ribosomes – the cellular machines that produce new proteins – and fewer proteins involved in providing the cell with chemical energy. In contrast, proteins implicated in the immune system, in the maintenance of existing proteins, and in processing other molecules called RNAs were more abundant in older muscles. Ubaida-Mohien et al. then looked more closely at changes involving RNA processing. Cells make proteins by copying DNA sequences into an RNA template and using this template to instruct the ribosomes on how to make the specific protein. Before the RNA can be ‘read’ by a ribosome, however, some parts must be cut out and others added, which can lead to different versions of the final RNA, also known as alternative transcripts. In order to check whether the difference in the levels of proteins that process RNAs was affecting the RNAs being produced, Ubaida-Mohien et al. extracted the RNAs from older and younger muscles and compared them. This showed that the RNA in older people had more alternative transcripts, confirming that the change in protein levels was having downstream effects. Currently, it is not possible to prevent or delay the loss of muscle strength associated with aging. Understanding how the protein make-up of muscles changes as humans grow older may help find new ways to prevent and perhaps even reverse this decline.
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Affiliation(s)
- Ceereena Ubaida-Mohien
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Alexey Lyashkov
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Marta Gonzalez-Freire
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Ravi Tharakan
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Michelle Shardell
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Ruin Moaddel
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | | | - Chee W Chia
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Myriam Gorospe
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Ranjan Sen
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Luigi Ferrucci
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, United States
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12
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Sonjak V, Jacob K, Morais JA, Rivera-Zengotita M, Spendiff S, Spake C, Taivassalo T, Chevalier S, Hepple RT. Fidelity of muscle fibre reinnervation modulates ageing muscle impact in elderly women. J Physiol 2019; 597:5009-5023. [PMID: 31368533 DOI: 10.1113/jp278261] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/30/2019] [Indexed: 12/23/2022] Open
Abstract
KEY POINTS Susceptibility to age-related muscle atrophy relates to the degree of muscle denervation and the capacity of successful reinnervation. However, the specific role of denervation as a determinant of the severity of muscle aging between populations with low versus high physical function has not been addressed. We show that prefrail/frail elderly women exhibited marked features of muscle denervation, whereas world class octogenarian female master athletes showed attenuated indices of denervation and greater reinnervation capacity. These findings suggest that the difference in age-related muscle impact between low- and high-functioning elderly women is the robustness of the response to denervation of myofibers. ABSTRACT Ageing muscle degeneration is a key contributor to physical frailty; however, the factors responsible for exacerbated vs. muted ageing muscle impact are largely unknown. Based upon evidence that susceptibility to neurogenic impact is an important determinant of the severity of ageing muscle degeneration, we aimed to determine the presence and extent of denervation in pre-frail/frail elderly (FE, 77.9 ± 6.2 years) women compared to young physically inactive (YI, 24.0 ± 3.5 years) females, and contrast these findings to high-functioning world class octogenarian female masters athletes (MA, 80.9 ± 6.6 years). Muscle biopsies from vastus lateralis muscle were obtained from all three groups to assess denervation-related morphological and transcriptional markers. The FE group displayed marked grouping of slow fibres, accumulation of very small myofibres, a severe reduction in type IIa/I size ratio, highly variable inter-subject accumulation of neural cell adhesion molecule (NCAM)-positive myofibres, and an accumulation of pyknotic nuclei, indicative of recurring cycles of denervation/reinnervation and persistent denervation. The MA group exhibited a smaller decline in type IIa/I size ratio and fewer pyknotic nuclei, accompanied by a higher degree of type I fibre grouping and larger fibre group size, suggesting a greater reinnervation of denervated fibres. Consistent with this interpretation, MA had higher mRNA levels of the reinnervation-promoting cytokine fibroblast growth factor binding protein 1 (FGFBP1) than FE. Our results indicate that the muscle of FE women has significant neurogenic atrophy, whereas MA muscle exhibit superior reinnervation capacity, suggesting that the difference in age-related muscle impact between low- and high-functioning elderly women is the robustness of the response to denervation of myofibres.
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Affiliation(s)
- Vita Sonjak
- Department of Kinesiology & Physical Education, McGill University, 475 Pine Avenue West, Montreal, Quebec, H2W1S4, Canada.,Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, Quebec, H4A3J1, Canada
| | - Kathryn Jacob
- Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, Quebec, H4A3J1, Canada
| | - José A Morais
- Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, Quebec, H4A3J1, Canada.,Division of Geriatric Medicine, McGill University, 1650 Cedar Avenue, Montreal, Quebec, H3G1A4, Canada.,School of Human Nutrition, McGill University, 21111 Lakeshore Dr, Saint-Anne-de-Bellevue, Quebec, H9X3L9, Canada
| | - Marie Rivera-Zengotita
- Department of Pathology Immunology and Laboratory Medicine, College of Medicine, University of Florida, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| | - Sally Spendiff
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, 401 Smyth Rd, Ottawa, Canada
| | - Carole Spake
- Medical School, Brown University, 222 Richmond St, Providence, RI, 02903, USA
| | - Tanja Taivassalo
- Department of Physiology and Functional Genomics, University of Florida, 1600 SW Archer Rd, Gainesville, FL, 32603, USA
| | - Stéphanie Chevalier
- Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, Quebec, H4A3J1, Canada.,Division of Geriatric Medicine, McGill University, 1650 Cedar Avenue, Montreal, Quebec, H3G1A4, Canada.,School of Human Nutrition, McGill University, 21111 Lakeshore Dr, Saint-Anne-de-Bellevue, Quebec, H9X3L9, Canada
| | - Russell T Hepple
- Department of Physiology and Functional Genomics, University of Florida, 1600 SW Archer Rd, Gainesville, FL, 32603, USA.,Department of Physical Therapy, University of Florida, 1225 Center Drive, Gainesville, FL, 32610, USA
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13
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McArdle A, Pollock N, Staunton CA, Jackson MJ. Aberrant redox signalling and stress response in age-related muscle decline: Role in inter- and intra-cellular signalling. Free Radic Biol Med 2019; 132:50-57. [PMID: 30508577 PMCID: PMC6709668 DOI: 10.1016/j.freeradbiomed.2018.11.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/29/2018] [Accepted: 11/29/2018] [Indexed: 12/22/2022]
Abstract
Age-associated frailty is predominantly due to loss of muscle mass and function. The loss of muscle mass is also associated with a greater loss of muscle strength, suggesting that the remaining muscle fibres are weaker than those of adults. The mechanisms by which muscle is lost with age are unclear, but in this review we aim to pull together various strands of evidence to explain how muscle contractions support proteostasis in non-muscle tissues, particularly focussed on the production and potential transfer of Heat Shock Proteins (HSPs) and how this may fail during ageing, Furthermore we will identify logical approaches, based on this hypothesis, by which muscle loss in ageing may be reduced. Skeletal muscle generates superoxide and nitric oxide at rest and this generation is increased by contractile activity. In adults, this increased generation of reactive oxygen and nitrogen species (RONS) activate redox-sensitive transcription factors such as nuclear factor κB (NFκB), activator protein-1 (AP1) and heat shock factor 1 (HSF1), resulting in increases in cytoprotective proteins such as the superoxide dismutases, catalase and heat shock proteins that prevent oxidative damage to tissues and facilitate remodelling and proteostasis in both an intra- and inter-cellular manner. During ageing, the ability of skeletal muscle from aged organisms to respond to an increase in ROS generation by increased expression of cytoprotective proteins through activation of redox-sensitive transcription factors is severely attenuated. This age-related lack of physiological adaptations to the ROS induced by contractile activity appears to contribute to a loss of ROS homeostasis, increased oxidative damage and age-related dysfunction in skeletal muscle and potentially other tissues.
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Affiliation(s)
- Anne McArdle
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Institute of Ageing and Chronic Disease, University of Liverpool, L7 8TX, United Kingdom.
| | - Natalie Pollock
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Institute of Ageing and Chronic Disease, University of Liverpool, L7 8TX, United Kingdom
| | - Caroline A Staunton
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Institute of Ageing and Chronic Disease, University of Liverpool, L7 8TX, United Kingdom
| | - Malcolm J Jackson
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Institute of Ageing and Chronic Disease, University of Liverpool, L7 8TX, United Kingdom
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14
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Arnold WD, Taylor RS, Li J, Nagy JA, Sanchez B, Rutkove SB. Electrical impedance myography detects age-related muscle change in mice. PLoS One 2017; 12:e0185614. [PMID: 29049394 PMCID: PMC5648130 DOI: 10.1371/journal.pone.0185614] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/16/2017] [Indexed: 12/14/2022] Open
Abstract
Loss of muscle mass and strength represents one of the most significant contributors to impaired function in older adults. Convenient and non-invasive biomarkers are needed that can readily identify and track age-related muscle change. Previous data has suggested electrical impedance myography (EIM) has the potential to serve in this capacity. In this study we investigated how changes in EIM compared with other standard measures of muscle structure and function in aged compared with young mice. A total of 19 male mice aged approximately 25 months and 19 male mice aged 3 months underwent surface multifrequency EIM of the right gastrocnemius muscle using standard methods. Fore and hind limb grip strength, sciatic compound muscle action potential amplitude, and in-situ force of the gastrocnemius were also measured; after sacrifice, gastrocnemius myofiber size was assessed using standard histology. Spearman correlation coefficients were calculated to investigate the association between EIM and muscle characteristics. EIM in aged animals demonstrated significantly lower 50 kHz impedance phase (p<0.001) and reactance (p<0.01) values as well as reduced multifrequency parameters. In contrast, absolute gastrocnemius muscle mass was no different between young and aged mice (p = 0.58) but was reduced in aged mice after normalization to body mass (p<0.001). Median myofiber size in the aged mice was not different from that of young mice (p = 0.72). Aged mice showed reduced muscle function on the basis of normalized fore limb (p<0.001) and normalized hind limb (p<0.001) grip strength, as well as normalized gastrocnemius twitch (p<0.001) and normalized maximal isometric force (p<0.001). Sciatic compound muscle action potential amplitude was reduced in aged mice (p<0.05). EIM parameters showed good correlation with reduced standard physiological and electrophysiological measures of muscle health. Our study suggests that EIM is sensitive to aged-related muscle change and may represent a convenient and valuable method of quantifying loss of muscle health.
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Affiliation(s)
- W. David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Rebecca S. Taylor
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jia Li
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Janice A. Nagy
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Benjamin Sanchez
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Seward B. Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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15
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Xu Z, Feng X, Dong J, Wang ZM, Lee J, Furdui C, Files DC, Beavers KM, Kritchevsky S, Milligan C, Jin JP, Delbono O, Zhang T. Cardiac troponin T and fast skeletal muscle denervation in ageing. J Cachexia Sarcopenia Muscle 2017; 8:808-823. [PMID: 28419739 PMCID: PMC5659053 DOI: 10.1002/jcsm.12204] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/13/2017] [Accepted: 03/01/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Ageing skeletal muscle undergoes chronic denervation, and the neuromuscular junction (NMJ), the key structure that connects motor neuron nerves with muscle cells, shows increased defects with ageing. Previous studies in various species have shown that with ageing, type II fast-twitch skeletal muscle fibres show more atrophy and NMJ deterioration than type I slow-twitch fibres. However, how this process is regulated is largely unknown. A better understanding of the mechanisms regulating skeletal muscle fibre-type specific denervation at the NMJ could be critical to identifying novel treatments for sarcopenia. Cardiac troponin T (cTnT), the heart muscle-specific isoform of TnT, is a key component of the mechanisms of muscle contraction. It is expressed in skeletal muscle during early development, after acute sciatic nerve denervation, in various neuromuscular diseases and possibly in ageing muscle. Yet the subcellular localization and function of cTnT in skeletal muscle is largely unknown. METHODS Studies were carried out on isolated skeletal muscles from mice, vervet monkeys, and humans. Immunoblotting, immunoprecipitation, and mass spectrometry were used to analyse protein expression, real-time reverse transcription polymerase chain reaction was used to measure gene expression, immunofluorescence staining was performed for subcellular distribution assay of proteins, and electromyographic recording was used to analyse neurotransmission at the NMJ. RESULTS Levels of cTnT expression in skeletal muscle increased with ageing in mice. In addition, cTnT was highly enriched at the NMJ region-but mainly in the fast-twitch, not the slow-twitch, muscle of old mice. We further found that the protein kinase A (PKA) RIα subunit was largely removed from, while PKA RIIα and RIIβ are enriched at, the NMJ-again, preferentially in fast-twitch but not slow-twitch muscle in old mice. Knocking down cTnT in fast skeletal muscle of old mice: (i) increased PKA RIα and reduced PKA RIIα at the NMJ; (ii) decreased the levels of gene expression of muscle denervation markers; and (iii) enhanced neurotransmission efficiency at NMJ. CONCLUSIONS Cardiac troponin T at the NMJ region contributes to NMJ functional decline with ageing mainly in the fast-twitch skeletal muscle through interfering with PKA signalling. This knowledge could inform useful targets for prevention and therapy of age-related decline in muscle function.
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Affiliation(s)
- Zherong Xu
- Department of Internal Medicine, Section on Gerontology and Geriatic Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Department of Geriatrics, First Affiliated Hospital, Zhejiang University, School of Medicine, Hangzhou, China
| | - Xin Feng
- Department of Otolaryngology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Juan Dong
- Department of Internal Medicine, Section on Gerontology and Geriatic Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Zhong-Min Wang
- Department of Internal Medicine, Section on Gerontology and Geriatic Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Jingyun Lee
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Cristina Furdui
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Daniel Clark Files
- Internal Medicine-Pulmonary, Critical Care, Allergy and Immunology, Gerontology and Geriatric Medicine and the Critical Illness Injury and Recovery Research Center, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Kristen M Beavers
- Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC, USA
| | - Stephen Kritchevsky
- Department of Internal Medicine, Section on Gerontology and Geriatic Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Carolanne Milligan
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Jian-Ping Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatic Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Tan Zhang
- Department of Internal Medicine, Section on Gerontology and Geriatic Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.,Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
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16
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The role of attenuated redox and heat shock protein responses in the age-related decline in skeletal muscle mass and function. Essays Biochem 2017; 61:339-348. [PMID: 28698308 DOI: 10.1042/ebc20160088] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 04/29/2017] [Accepted: 05/11/2017] [Indexed: 11/17/2022]
Abstract
The loss of muscle mass and weakness that accompanies ageing is a major contributor to physical frailty and loss of independence in older people. A failure of muscle to adapt to physiological stresses such as exercise is seen with ageing and disruption of redox regulated processes and stress responses are recognized to play important roles in theses deficits. The role of redox regulation in control of specific stress responses, including the generation of heat shock proteins (HSPs) by muscle appears to be particularly important and affected by ageing. Transgenic and knockout studies in experimental models in which redox and HSP responses were modified have demonstrated the importance of these processes in maintenance of muscle mass and function during ageing. New data also indicate the potential of these processes to interact with and influence ageing in other tissues. In particular the roles of redox signalling and HSPs in regulation of inflammatory pathways appears important in their impact on organismal ageing. This review will briefly indicate the importance of this area and demonstrate how an understanding of the manner in which redox and stress responses interact and how they may be controlled offers considerable promise as an approach to ameliorate the major functional consequences of ageing of skeletal muscle (and potentially other tissues) in man.
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17
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Vasilaki A, Pollock N, Giakoumaki I, Goljanek-Whysall K, Sakellariou GK, Pearson T, Kayani A, Jackson MJ, McArdle A. The effect of lengthening contractions on neuromuscular junction structure in adult and old mice. AGE (DORDRECHT, NETHERLANDS) 2016; 38:259-272. [PMID: 27470432 PMCID: PMC5061675 DOI: 10.1007/s11357-016-9937-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 07/14/2016] [Indexed: 06/06/2023]
Abstract
Skeletal muscles of old mice demonstrate a profound inability to regenerate fully following damage. Such a failure could be catastrophic to older individuals where muscle loss is already evident. Degeneration and regeneration of muscle fibres following contraction-induced injury in adult and old mice are well characterised, but little is known about the accompanying changes in motor neurons and neuromuscular junctions (NMJs) following this form of injury although defective re-innervation of muscle following contraction-induced damage has been proposed to play a role in sarcopenia. This study visualised and quantified structural changes to motor neurons and NMJs in Extensor digitorum longus (EDL) muscles of adult and old Thy1-YFP transgenic mice during regeneration following contraction-induced muscle damage. Data demonstrated that the damaging contraction protocol resulted in substantial initial disruption to NMJs in muscles of adult mice, which was reversed entirely within 28 days following damage. In contrast, in quiescent muscles of old mice, ∼15 % of muscle fibres were denervated and ∼80 % of NMJs showed disruption. This proportion of denervated and partially denervated fibres remained unchanged following recovery from contraction-induced damage in muscles of old mice although ∼25 % of muscle fibres were completely lost by 28 days post-contractions. Thus, in old mice, the failure to restore full muscle force generation that occurs following damage does not appear to be due to any further deficit in the percentage of disrupted NMJs, but appears to be due, at least in part, to the complete loss of muscle fibres following damage.
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Affiliation(s)
- Aphrodite Vasilaki
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Natalie Pollock
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Ifigeneia Giakoumaki
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Katarzyna Goljanek-Whysall
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Giorgos K Sakellariou
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Timothy Pearson
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Anna Kayani
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Malcolm J Jackson
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Anne McArdle
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK.
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18
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McDonagh B, Scullion SM, Vasilaki A, Pollock N, McArdle A, Jackson MJ. Ageing-induced changes in the redox status of peripheral motor nerves imply an effect on redox signalling rather than oxidative damage. Free Radic Biol Med 2016; 94:27-35. [PMID: 26876649 PMCID: PMC4851218 DOI: 10.1016/j.freeradbiomed.2016.02.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/02/2016] [Accepted: 02/05/2016] [Indexed: 01/17/2023]
Abstract
Ageing is associated with loss of skeletal muscle fibres, atrophy of the remaining fibres and weakness. These changes in muscle are accompanied by disruption of motor neurons and neuromuscular junctions although the direct relationship between the nerve and muscle degeneration is not understood. Oxidative changes have been implicated in the mechanisms leading to age-related loss of muscle mass and in degeneration of the central nervous system, but little is known about age-related changes in oxidation in specific peripheral nerves that supply muscles that are affected by ageing. We have therefore examined the sciatic nerve of old mice at an age when loss of tibialis anterior muscle mass and function is apparent. Sciatic nerve from old mice did not show a gross increase in oxidative damage, but electron paramagnetic resonance (EPR) studies indicated an increase in the activity of superoxide and/or peroxynitrite in the nerves of old mice at rest that was further exacerbated by electrical stimulation of the nerve to activate muscle contractions. Proteomic analyses indicated that specific redox-sensitive proteins are increased in content in the nerves of old mice that may reflect an adaptation to regulate the increased superoxide/peroxynitrite and maintain redox homoeostasis. Analysis of redox active cysteines showed some increase in reversible oxidation in specific proteins in nerves of old mice, but this was not universally seen across all redox-active cysteines. Detailed analysis of the redox-active cysteine in one protein in the nerve of old mice that is key to redox signalling (Peroxiredoxin 6, Cys 47) showed a minor increase in reversible oxidation that would be compatible with a change in its redox signalling function. In conclusion, the data presented indicate that sciatic nerve from old mice does not show a gross increase in oxidative damage similar to that seen in the TA and other muscles that it innervates. Our results indicate an adaptation to increased oxidation with minor changes in the oxidation of key cysteines that may contribute to defective redox signalling in the nerve.
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Key Words
- cp, 3-carboxy-proxyl
- cph, 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine
- nav1.5, voltage gated sodium channel isoform
- ncam, neural cell adhesion molecule
- nem, n-ethylmaleimide
- nmj, neuromuscular junction
- nox2, nad(p)h oxidase 2
- prdx, peroxiredoxin
- sod1, cuzn superoxide dismutase
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Affiliation(s)
- Brian McDonagh
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Siobhan M Scullion
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Aphrodite Vasilaki
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Natalie Pollock
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Anne McArdle
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Malcolm J Jackson
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK.
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Messi ML, Li T, Wang ZM, Marsh AP, Nicklas B, Delbono O. Resistance Training Enhances Skeletal Muscle Innervation Without Modifying the Number of Satellite Cells or their Myofiber Association in Obese Older Adults. J Gerontol A Biol Sci Med Sci 2015; 71:1273-80. [PMID: 26447161 DOI: 10.1093/gerona/glv176] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/17/2015] [Indexed: 11/14/2022] Open
Abstract
Studies in humans and animal models provide compelling evidence for age-related skeletal muscle denervation, which may contribute to muscle fiber atrophy and loss. Skeletal muscle denervation seems relentless; however, long-term, high-intensity physical activity appears to promote muscle reinnervation. Whether 5-month resistance training (RT) enhances skeletal muscle innervation in obese older adults is unknown. This study found that neural cell-adhesion molecule, NCAM+ muscle area decreased with RT and was inversely correlated with muscle strength. NCAM1 and RUNX1 gene transcripts significantly decreased with the intervention. Type I and type II fiber grouping in the vastus lateralis did not change significantly but increases in leg press and knee extensor strength inversely correlated with type I, but not with type II, fiber grouping. RT did not modify the total number of satellite cells, their number per area, or the number associated with specific fiber subtypes or innervated/denervated fibers. Our results suggest that RT has a beneficial impact on skeletal innervation, even when started late in life by sedentary obese older adults.
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Affiliation(s)
- María Laura Messi
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine and J Paul Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Tao Li
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine and J Paul Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Zhong-Min Wang
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine and J Paul Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Anthony P Marsh
- Department of Health and Exercise Science, Wake Forest University, Winston-Salem, North Carolina
| | - Barbara Nicklas
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine and J Paul Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine and J Paul Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina.
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Jackson MJ. Redox regulation of muscle adaptations to contractile activity and aging. J Appl Physiol (1985) 2015; 119:163-71. [PMID: 25792715 PMCID: PMC4526708 DOI: 10.1152/japplphysiol.00760.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/08/2015] [Indexed: 11/22/2022] Open
Abstract
Superoxide and nitric oxide are generated by skeletal muscle, and these species are increased by contractile activity. Mitochondria have long been assumed to play the primary role in generation of superoxide in muscle, but recent studies indicate that, during contractile activity, membrane-localized NADPH oxidase(s) rapidly generate(s) superoxide that plays a role in redox signaling. This process is important in upregulation of rapid and specific cytoprotective responses that aid maintenance of cell viability following contractile activity, but the overall extent to which redox signaling contributes to regulation of muscle metabolism and homeostasis following contractile activity is currently unclear, as is identification of key redox-sensitive protein targets involved in these processes. Reactive oxygen and nitrogen species have also been implicated in the loss of muscle mass and function that occurs with aging, although recent work has questioned whether oxidative damage plays a key role in these processes. A failure of redox signaling occurs in muscle during aging and may contribute to the age-related loss of muscle fibers. Whether such changes in redox signaling reflect primary age-related changes or are secondary to the fundamental mechanisms is unclear. For instance, denervated muscle fibers within muscles from aged rodents or humans appear to generate large amounts of mitochondrial hydrogen peroxide that could influence adjacent innervated fibers. Thus, in this instance, a "secondary" source of reactive oxygen species may be potentially generated as a result of a primary age-related pathology (loss of neurons), but, nevertheless, may contribute to loss of muscle mass and function during aging.
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Affiliation(s)
- Malcolm J Jackson
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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21
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Hepple RT. Mitochondrial involvement and impact in aging skeletal muscle. Front Aging Neurosci 2014; 6:211. [PMID: 25309422 PMCID: PMC4159998 DOI: 10.3389/fnagi.2014.00211] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 07/30/2014] [Indexed: 01/07/2023] Open
Abstract
Atrophy is a defining feature of aging skeletal muscle that contributes to progressive weakness and an increased risk of mobility impairment, falls, and physical frailty in very advanced age. Amongst the most frequently implicated mechanisms of aging muscle atrophy is mitochondrial dysfunction. Recent studies employing methods that are well-suited to interrogating intrinsic mitochondrial function find that mitochondrial respiration and reactive oxygen species emission changes are inconsistent between aging rat muscles undergoing atrophy and appear normal in human skeletal muscle from septuagenarian physically active subjects. On the other hand, a sensitization to permeability transition seems to be a general property of atrophying muscle with aging and this effect is even seen in atrophying muscle from physically active septuagenarian subjects. In addition to this intrinsic alteration in mitochondrial function, factors extrinsic to the mitochondria may also modulate mitochondrial function in aging muscle. In particular, recent evidence implicates oxidative stress in the aging milieu as a factor that depresses respiratory function in vivo (an effect that is not present ex vivo). Furthermore, in very advanced age, not only does muscle atrophy become more severe and clinically relevant in terms of its impact, but also there is evidence that this is driven by an accumulation of severely atrophied denervated myofibers. As denervation can itself modulate mitochondrial function and recruit mitochondrial-mediated atrophy pathways, future investigations need to address the degree to which skeletal muscle mitochondrial alterations in very advanced age are a consequence of denervation, rather than a primary organelle defect, to refine our understanding of the relevance of mitochondria as a therapeutic target at this more advanced age.
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Affiliation(s)
- Russell T Hepple
- Department of Kinesiology, McGill University Health Center, McGill University , Montreal, QC , Canada
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Christie AD, Tonson A, Larsen RG, DeBlois JP, Kent JA. Human skeletal muscle metabolic economy in vivo: effects of contraction intensity, age, and mobility impairment. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1124-35. [PMID: 25163917 DOI: 10.1152/ajpregu.00083.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We tested the hypothesis that older muscle has greater metabolic economy (ME) in vivo than young, in a manner dependent, in part, on contraction intensity. Twenty young (Y; 24±1 yr, 10 women), 18 older healthy (O; 73±2, 9 women) and 9 older individuals with mild-to-moderate mobility impairment (OI; 74±1, 7 women) received stimulated twitches (2 Hz, 3 min) and performed nonfatiguing voluntary (20, 50, and 100% maximal; 12 s each) isometric dorsiflexion contractions. Torque-time integrals (TTI; Nm·s) were calculated and expressed relative to maximal fat-free muscle cross-sectional area (cm2), and torque variability during voluntary contractions was calculated as the coefficient of variation. Total ATP cost of contraction (mM) was determined from flux through the creatine kinase reaction, nonoxidative glycolysis and oxidative phosphorylation, and used to calculate ME (Nm·s·cm(-2)·mM ATP(-1)). While twitch torque relaxation was slower in O and OI compared with Y (P≤0.001), twitch TTI, ATP cost, and economy were similar across groups (P≥0.15), indicating comparable intrinsic muscle economy during electrically induced isometric contractions in vivo. During voluntary contractions, normalized TTI and total ATP cost did not differ significantly across groups (P≥0.20). However, ME was lower in OI than Y or O at 20% and 50% MVC (P≤0.02), and torque variability was greater in OI than Y or O at 20% MVC (P≤0.05). These results refute the hypothesis of greater muscle ME in old age, and provide support for lower ME in impaired older adults as a potential mechanism or consequence of age-related reductions in functional mobility.
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Affiliation(s)
- Anita D Christie
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Anne Tonson
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Ryan G Larsen
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Jacob P DeBlois
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
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Gonzalez-Freire M, de Cabo R, Studenski SA, Ferrucci L. The Neuromuscular Junction: Aging at the Crossroad between Nerves and Muscle. Front Aging Neurosci 2014; 6:208. [PMID: 25157231 PMCID: PMC4127816 DOI: 10.3389/fnagi.2014.00208] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/25/2014] [Indexed: 01/19/2023] Open
Abstract
Aging is associated with a progressive loss of muscle mass and strength and a decline in neurophysiological functions. Age-related neuromuscular junction (NMJ) plays a key role in musculoskeletal impairment that occurs with aging. However, whether changes in the NMJ precede or follow the decline of muscle mass and strength remains unresolved. Many factors such as mitochondrial dysfunction, oxidative stress, inflammation, changes in the innervation of muscle fibers, and mechanical properties of the motor units probably perform an important role in NMJ degeneration and muscle mass and strength decline in late life. This review addresses the primary events that might lead to NMJ dysfunction with aging, including studies on biomarkers, signaling pathways, and animal models. Interventions such as caloric restriction and exercise may positively affect the NMJ through this mechanism and attenuate the age-related progressive impairment in motor function.
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Affiliation(s)
- Marta Gonzalez-Freire
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA ; Longitudinal Studies Section, Baltimore Longitudinal Study of Aging, National Institute on Aging, National Institutes of Health , Baltimore, MD , USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA
| | - Stephanie A Studenski
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA ; Longitudinal Studies Section, Baltimore Longitudinal Study of Aging, National Institute on Aging, National Institutes of Health , Baltimore, MD , USA
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA ; Longitudinal Studies Section, Baltimore Longitudinal Study of Aging, National Institute on Aging, National Institutes of Health , Baltimore, MD , USA
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Rygiel KA, Grady JP, Turnbull DM. Respiratory chain deficiency in aged spinal motor neurons. Neurobiol Aging 2014; 35:2230-8. [PMID: 24684792 PMCID: PMC4099519 DOI: 10.1016/j.neurobiolaging.2014.02.027] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/13/2014] [Accepted: 02/27/2014] [Indexed: 01/10/2023]
Abstract
Sarcopenia, muscle wasting, and strength decline with age, is an important cause of loss of mobility in the elderly individuals. The underlying mechanisms are uncertain but likely to involve defects of motor nerve, neuromuscular junction, and muscle. Loss of motor neurons with age and subsequent denervation of skeletal muscle has been recognized as one of the contributing factors. This study investigated aspects of mitochondrial biology in spinal motor neurons from elderly subjects. We found that protein components of complex I of mitochondrial respiratory chain were reduced or absent in a proportion of aged motor neurons–a phenomenon not observed in fetal tissue. Further investigation showed that complex I-deficient cells had reduced mitochondrial DNA content and smaller soma size. We propose that mitochondrial dysfunction in these motor neurons could lead to the cell loss and ultimately denervation of muscle fibers.
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Affiliation(s)
- Karolina A Rygiel
- Newcastle University Centre for Brain Ageing and Vitality, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, UK; Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - John P Grady
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Newcastle University Centre for Brain Ageing and Vitality, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, UK; Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
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25
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Jackson MJ. Interactions between reactive oxygen species generated by contractile activity and aging in skeletal muscle? Antioxid Redox Signal 2013; 19:804-12. [PMID: 23682926 PMCID: PMC3749718 DOI: 10.1089/ars.2013.5383] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
SIGNIFICANCE Aging leads to a loss of skeletal muscle mass and function that causes instability, increased risk of falls, and need for residential care. This is due to a reduction in the muscle mass and strength that is primarily due caused by a decrease in the number of muscle fibers, particularly, type II fibers, and atrophy and weakening of those remaining. RECENT ADVANCES Although increased oxidative damage was originally thought to be the key to the aging process, data now indicate that reactive oxygen species (ROS) may be one of the several components of the degenerative processes in aging. The skeletal muscle shows important rapid adaptations to the ROS generated by contractions that are attenuated in aged organisms and transgenic studies have indicated that overcoming these attenuated responses can prevent the age-related loss of muscle mass and function. CRITICAL ISSUES Elucidation of the mechanisms by which the skeletal muscle adapts to the ROS generated to contractions and the way in which these processes are attenuated by aging is critical to the development of logical approaches to prevent age-related loss of muscle mass and function. FUTURE DIRECTIONS Future studies are likely to focus on the redox regulation of adaptive pathways and their maintenance during aging as an approach to maintain and improve muscle function.
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Affiliation(s)
- Malcolm J Jackson
- MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing CIMA, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, United Kingdom.
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Palomero J, Vasilaki A, Pye D, McArdle A, Jackson MJ. Aging increases the oxidation of dichlorohydrofluorescein in single isolated skeletal muscle fibers at rest, but not during contractions. Am J Physiol Regul Integr Comp Physiol 2013; 305:R351-8. [PMID: 23697797 PMCID: PMC3833391 DOI: 10.1152/ajpregu.00530.2012] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
An increase in the activity of reactive oxygen species (ROS) has been implicated in the mechanisms of loss of skeletal muscle that occurs during aging, but few studies have attempted to directly assess activities in intact muscle fibers. The current project used the nonspecific fluorescent probe for ROS and reactive nitrogen species, 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein (CM-DCFH), in single, isolated, mature skeletal muscle fibers from adult and old mice in addition to biochemical measurements of key regulatory proteins for ROS in muscles of these animals. Data confirmed the changes in key regulatory processes for ROS (increased glutathione peroxidase 1 and catalase activities and reduced total glutathione content) previously reported in muscle from old mice and showed increased CM-DCFH oxidation in muscle fibers from old mice at rest and indicate that these changes are likely due to an increase in generation of oxidants rather than a lack of scavenging capacity. The increased CM-DCFH oxidation persisted even when cellular defenses against oxidants were increased by loading fibers from young and old mice with glutathione. During contractile activity, and in contrast to the increase observed in fibers from young mice, there was no further increase in CM-DCFH oxidation in muscle fibers from old mice. These data also suggest that the defect in short-term adaptations to contractions that occurs in old mice may be related to a diminished, or absent, increase in the muscle generation of ROS and/or reactive nitrogen species that normally accompanies contractile activity in young mice.
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Affiliation(s)
- Jesus Palomero
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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27
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Personius KE, Parker SD. TrkB expression at the neuromuscular junction is reduced during aging. Muscle Nerve 2012. [PMID: 23180620 DOI: 10.1002/mus.23616] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Full-length tyrosine kinase B (TrkB.FL) and truncated TrkB (TrkB.t1) receptors are colocalized with acetylcholine receptors (AChRs) at the neuromuscular junction. We have recently shown that reduced TrkB expression leads to age-related alterations in AChR structure, neurotransmission failure, and muscle weakness. METHODS We investigated whether TrkB expression is reduced in the soleus muscle during aging. RESULTS TrkB protein expression was decreased in senescent (24-month-old) compared with 3-12-month-old mice. Loss of TrkB expression was concurrent with age-related changes in AChR morphology. Changes in mRNA levels did not correlate with protein expression, because TrkB.FL copy number was increased in the senescent soleus. No change was seen in TrkB.t1 levels. CONCLUSIONS The results suggest that reduced TrkB expression during aging may result from reduced TrkB.FL mRNA translation or increased TrkB protein turnover. Thus, maintaining adequate TrkB signaling is a potential therapeutic tool to improve muscle function during senescence.
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Affiliation(s)
- Kirkwood E Personius
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA.
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Affiliation(s)
- Russell T. Hepple
- Department of Kinesiology, Department of Medicine, McGill University, Montreal, Canada
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Denervation causes fiber atrophy and myosin heavy chain co-expression in senescent skeletal muscle. PLoS One 2012; 7:e29082. [PMID: 22235261 PMCID: PMC3250397 DOI: 10.1371/journal.pone.0029082] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 11/21/2011] [Indexed: 01/06/2023] Open
Abstract
Although denervation has long been implicated in aging muscle, the degree to which it is causes the fiber atrophy seen in aging muscle is unknown. To address this question, we quantified motoneuron soma counts in the lumbar spinal cord using choline acetyl transferase immunhistochemistry and quantified the size of denervated versus innervated muscle fibers in the gastrocnemius muscle using the in situ expression of the denervation-specific sodium channel, Nav1.5, in young adult (YA) and senescent (SEN) rats. To gain insights into the mechanisms driving myofiber atrophy, we also examined the myofiber expression of the two primary ubiquitin ligases necessary for muscle atrophy (MAFbx, MuRF1). MN soma number in lumbar spinal cord declined 27% between YA (638±34 MNs×mm−1) and SEN (469±13 MNs×mm−1). Nav1.5 positive fibers (1548±70 μm2) were 35% smaller than Nav1.5 negative fibers (2367±78 μm2; P<0.05) in SEN muscle, whereas Nav1.5 negative fibers in SEN were only 7% smaller than fibers in YA (2553±33 μm2; P<0.05) where no Nav1.5 labeling was seen, suggesting denervation is the primary cause of aging myofiber atrophy. Nav1.5 positive fibers had higher levels of MAFbx and MuRF1 (P<0.05), consistent with involvement of the proteasome proteolytic pathway in the atrophy of denervated muscle fibers in aging muscle. In summary, our study provides the first quantitative assessment of the contribution of denervation to myofiber atrophy in aging muscle, suggesting it explains the majority of the atrophy we observed. This striking result suggests a renewed focus should be placed on denervation in seeking understanding of the causes of and treatments for aging muscle atrophy.
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Striking denervation of neuromuscular junctions without lumbar motoneuron loss in geriatric mouse muscle. PLoS One 2011; 6:e28090. [PMID: 22164231 PMCID: PMC3229526 DOI: 10.1371/journal.pone.0028090] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 11/01/2011] [Indexed: 01/06/2023] Open
Abstract
Reasons for the progressive age-related loss of skeletal muscle mass and function, namely sarcopenia, are complex. Few studies describe sarcopenia in mice, although this species is the mammalian model of choice for genetic intervention and development of pharmaceutical interventions for muscle degeneration. One factor, important to sarcopenia-associated neuromuscular change, is myofibre denervation. Here we describe the morphology of the neuromuscular compartment in young (3 month) compared to geriatric (29 month) old female C57Bl/6J mice. There was no significant difference in the size or number of motoneuron cell bodies at the lumbar level (L1–L5) of the spinal cord at 3 and 29 months. However, in geriatric mice, there was a striking increase (by ∼2.5 fold) in the percentage of fully denervated neuromuscular junctions (NMJs) and associated deterioration of Schwann cells in fast extensor digitorum longus (EDL), but not in slow soleus muscles. There were also distinct changes in myofibre composition of lower limb muscles (tibialis anterior (TA) and soleus) with a shift at 29 months to a faster phenotype in fast TA muscle and to a slower phenotype in slow soleus muscle. Overall, we demonstrate complex changes at the NMJ and muscle levels in geriatric mice that occur despite the maintenance of motoneuron cell bodies in the spinal cord. The challenge is to identify which components of the neuromuscular system are primarily responsible for the marked changes within the NMJ and muscle, in order to selectively target future interventions to reduce sarcopenia.
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Delbono O. Expression and regulation of excitation-contraction coupling proteins in aging skeletal muscle. Curr Aging Sci 2011; 4:248-59. [PMID: 21529320 PMCID: PMC9634721 DOI: 10.2174/1874609811104030248] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 05/10/2010] [Accepted: 05/10/2010] [Indexed: 11/22/2022]
Abstract
Functional and structural decline of the neuromuscular system is a recognized cause of decreased strength, impaired performance of daily living activities, and loss of independence in the elderly. However, in mammals, including humans, age-related loss of strength is greater than loss of muscle mass, so the underlying mechanisms remain only partially understood. This review focuses on the mechanisms underlying impaired skeletal muscle function with aging, including external calcium-dependent skeletal muscle contraction; increased voltage-sensitive calcium channel Cav1.1 β1asubunit and junctional face protein JP-45 and decreased Cav1.1 (α1) expression, and the potential role of these and other recently discovered molecules of the muscle T-tubule/sarcoplasmic reticulum junction in excitation-contraction uncoupling. We also examined neural influences and trophic factors, particularly insulin-like growth factor-I (IGF-1). Better insight into the triad proteins' involvement in muscle ECC and nerve/muscle interactions and regulation will lead to more rational interventions to delay or prevent muscle weakness with aging. The focus of this review is on the proteins mediating excitation-contraction coupling (ECC) and their expression and regulation in humans and rodent models of skeletal muscle functional decline with aging. Age-dependent changes in proteins other than those related to ECC, muscle composition, clinical assessment and interventions, have been extensively reviewed recently [1-3].
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Affiliation(s)
- Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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Kulakowski SA, Parker SD, Personius KE. Reduced TrkB expression results in precocious age-like changes in neuromuscular structure, neurotransmission, and muscle function. J Appl Physiol (1985) 2011; 111:844-52. [PMID: 21737823 DOI: 10.1152/japplphysiol.00070.2011] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acute blockade of signaling through the tyrosine kinase receptor B (TrkB) attenuates neuromuscular transmission and fragments postsynaptic acetylcholine receptors (AChRs) in adult mice, suggesting that TrkB signaling is a key regulator of neuromuscular function. Using immunohistochemical, histological, and in vitro muscle contractile techniques, we tested the hypothesis that constitutively reduced TrkB expression would disrupt neuromuscular pre- and postsynaptic structure, neurotransmission, muscle fiber size, and muscle function in the soleus muscle of 6- to 8-mo-old TrkB⁺/⁻ mice compared with age-matched littermates. Age-like expansion of postsynaptic AChR area, AChR fragmentation, and denervation was observed in TrkB⁺/⁻ mice similar to that found in 24-mo-old wild-type mice. Neurotransmission failure was increased in TrkB⁺/⁻ mice, suggesting that these morphologic changes were sufficient to alter synaptic function. Reduced TrkB expression resulted in decreased muscle strength and fiber cross-sectional area. Immunohistochemical and muscle retrograde labeling experiments show that motor neuron number and size are unaffected in TrkB⁺/⁻ mice. These results suggest that TrkB- signaling at the neuromuscular junction plays a role in synaptic stabilization, neurotransmission, and muscle function and may impact the aging process of sarcopenia.
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Affiliation(s)
- Scott A Kulakowski
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
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Rahnert JA, Luo Q, Balog EM, Sokoloff AJ, Burkholder TJ. Changes in growth-related kinases in head, neck and limb muscles with age. Exp Gerontol 2010; 46:282-91. [PMID: 21095226 DOI: 10.1016/j.exger.2010.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 10/20/2010] [Accepted: 11/07/2010] [Indexed: 12/21/2022]
Abstract
Sarcopenia coincides with declines in several systemic processes that signal through the MAP kinase and Akt-mTOR-p70S6k cascades typically associated with muscle growth. Effects of aging on these pathways have primarily been examined in limb muscles, which experience substantial activity and neural changes in addition to systemic hormonal and metabolic changes. Head and neck muscles are reported to undergo reduced sarcopenia and disuse with age relative to limb muscles, suggesting muscle activity may contribute to maintaining mass with age. However many head and neck muscles derive from embryonic branchial arches, rather than the somites from which limb muscles originate, suggesting that developmental origin may be important. This study compares the expression and phosphorylation of MAP kinase and mTOR networks in head, neck, tongue, and limb muscles from 8- and 26-month old F344 rats to test the hypothesis that physical activity and developmental origin contribute to preservation of muscle mass with age. Phosphorylation of p38 was exaggerated in aged branchial arch muscles. Phosphorylation of ERK and p70S6k T421/S424 declined with age only in the biceps brachii. Expression of p70S6k declined in all head and neck, tongue and limb muscles although no change in phosphorylation of p70S6k on T389 could be resolved. A systemic change that results in a loss of p70S6k protein expression may reduce the capacity to respond to acute hypertrophic stimuli, while the exaggerated p38 signaling in branchial arch muscles may reflect more active muscle remodeling.
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Affiliation(s)
- Jill A Rahnert
- School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Sodium channel Na(V)1.5 expression is enhanced in cultured adult rat skeletal muscle fibers. J Membr Biol 2010; 235:109-19. [PMID: 20517693 DOI: 10.1007/s00232-010-9262-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 05/10/2010] [Indexed: 12/19/2022]
Abstract
This study analyzes changes in the distribution, electrophysiological properties, and proteic composition of voltage-gated sodium channels (Na(V)) in cultured adult rat skeletal muscle fibers. Patch clamp and molecular biology techniques were carried out in flexor digitorum brevis (FDB) adult rat skeletal muscle fibers maintained in vitro after cell dissociation with collagenase. After 4 days of culture, an increase of the Na(V)1.5 channel type was observed. This was confirmed by an increase in TTX-resistant channels and by Western blot test. These channels exhibited increased activation time constant (tau(m)) and reduced conductance, similar to what has been observed in denervated muscles in vivo, where the density of Na(V)1.5 was increasing progressively after denervation. By real-time polymerase chain reaction, we found that the expression of beta subunits was also modified, but only after 7 days of culture: increase in beta(1) without beta(4) modifications. beta(1) subunit is known to induce a negative shift of the inactivation curve, thus reducing current amplitude and duration. At day 7, tau(h) was back to normal and tau(m) still increased, in agreement with a decrease in sodium current and conductance at day 4 and normalization at day 7. Our model is a useful tool to study the effects of denervation in adult muscle fibers in vitro and the expression of sodium channels. Our data evidenced an increase in Na(V)1.5 channels and the involvement of beta subunits in the regulation of sodium current and fiber excitability.
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Ljubicic V, Hood DA. Diminished contraction-induced intracellular signaling towards mitochondrial biogenesis in aged skeletal muscle. Aging Cell 2009; 8:394-404. [PMID: 19416128 DOI: 10.1111/j.1474-9726.2009.00483.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The intent of this study was to determine whether aging affects signaling pathways involved in mitochondrial biogenesis in response to a single bout of contractile activity. Acute stimulation (1 Hz, 5 min) of the tibialis anterior (TA) resulted in a greater rate of fatigue in old (36 month), compared to young (6 month) F344XBN rats, which was associated with reduced ATP synthesis and a lower mitochondrial volume. To investigate fiber type-specific signaling, the TA was sectioned into red (RTA) and white (WTA) portions, possessing two- to 2.5-fold differences in mitochondrial content. The expression and contraction-mediated phosphorylation of p38, MKK3/6, CaMKII and AMPKalpha were assessed. Kinase protein expression tended to be higher in fiber sections with lower mitochondrial content, such as the WTA, relative to the RTA muscle, and this was exaggerated in tissues from senescent, compared to young animals. At rest, kinase activation was generally similar between young and old animals, despite the age-related variations in mitochondrial volume. In response to contractile activity, age did not influence the signaling of these kinases in the high-oxidative RTA muscle. However, in the low-oxidative WTA muscle, contraction-induced kinase activation was attenuated in old animals, despite the greater metabolic stress imposed by contractile activity in this muscle. Thus, the reduction of contraction-evoked kinase phosphorylation in muscle from old animals is fiber type-specific, and depends on factors which are, in part, independent of the metabolic milieu within the contracting fibers. These findings imply that the downstream consequences of kinase signaling are reduced in aging muscle.
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Payne AM, Jimenez-Moreno R, Wang ZM, Messi ML, Delbono O. Role of Ca2+, membrane excitability, and Ca2+ stores in failing muscle contraction with aging. Exp Gerontol 2008; 44:261-73. [PMID: 18948183 DOI: 10.1016/j.exger.2008.09.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 09/18/2008] [Accepted: 09/21/2008] [Indexed: 10/21/2022]
Abstract
Excitation-contraction (EC) coupling in a population of skeletal muscle fibers of aged mice becomes dependent on the presence of external Ca(2+) ions (Payne, A.M., Zheng, Z., Gonzalez, E., Wang, Z.M., Messi, M.L., Delbono, O., 2004b. External Ca(2+)-dependent excitation - contraction coupling in a population of aging mouse skeletal muscle fibers. J. Physiol. 560, 137-155.). However, the mechanism(s) underlying this process remain unknown. In this work, we examined the role of (1) extracellular Ca(2+); (2) voltage-induced influx of external Ca(2+) ions; (3) sarcoplasmic reticulum (SR) Ca(2+) depletion during repeated contractions; (4) store-operated Ca(2+) entry (SOCE); (5) SR ultrastructure; (6) SR subdomain localization of the ryanodine receptor; and (7) sarcolemmal excitability in muscle force decline with aging. These experiments show that external Ca(2+), but not Ca(2+) influx, is needed to maintain force upon repetitive fiber electrical stimulation. Decline in fiber force is associated with depressed SR Ca(2+) release. SR Ca(2+) depletion, SOCE, and the putative segregated Ca(2+) release store do not play a significant role in external Ca(2+)-dependent contraction. More importantly, a significant number of action potentials fail in senescent mouse muscle fibers subjected to a stimulation frequency. These results indicate that failure to generate action potentials accounts for decreased intracellular Ca(2+) mobilization and tetanic force in aging muscle exposed to a Ca(2+)-free medium.
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Affiliation(s)
- Anthony Michael Payne
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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Luin E, Ruzzier F. The role of L- and T-type Ca2+ currents during the in vitro aging of murine myogenic (i28) cells in culture. Cell Calcium 2007; 41:479-89. [PMID: 17064763 DOI: 10.1016/j.ceca.2006.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 07/28/2006] [Accepted: 09/10/2006] [Indexed: 01/29/2023]
Abstract
The age-related decline in skeletal muscle strength could, in part, result from alterations in the mechanism of excitation-contraction coupling, responsible for muscle contraction. In the present work, we used the in vitro aging of murine myogenic (i28) cells as a model, to investigate whether the inefficiency of aged satellite cells to generate functional skeletal muscle fibres could be partly due to defective voltage-dependent Ca2+ currents. The whole-cell patch clamp technique was employed to measure L- and T-type Ca2+ currents in myotubes derived from the differentiation and fusion of these cells reaching replicative senescence. Our data showed that the expression and the amplitude of these currents decreased significantly during in vitro aging. Moreover, the analysis of the L-type current evoked in young and old cells by positive voltage steps, revealed no differences in the kinetics of activation, but significant alterations in the rate of inactivation. These effects of in vitro aging on voltage-dependent Ca2+ currents could also be related to their inability to fuse into myotubes. Taken together, our data support the hypothesis that age-related effects on voltage-dependent L- and T-type currents could be one of the causes of the failure of satellite cells to efficiently counteract the impairment in muscle force.
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Affiliation(s)
- Elisa Luin
- Department of Physiology and Pathology and Centre for Neuroscience BRAIN, University of Trieste, Via A. Fleming 22, I-34127 Trieste, Italy.
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Payne AM, Messi ML, Zheng Z, Delbono O. Motor neuron targeting of IGF-1 attenuates age-related external Ca2+-dependent skeletal muscle contraction in senescent mice. Exp Gerontol 2006; 42:309-19. [PMID: 17174053 PMCID: PMC2063746 DOI: 10.1016/j.exger.2006.11.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 10/25/2006] [Accepted: 11/03/2006] [Indexed: 11/25/2022]
Abstract
A population of fast muscle fibers from aging mice is dependent on external Ca(2+) to maintain tetanic force during repeated contractions. We hypothesized that age-related denervation in muscle fibers plays a role in initiating this contractile deficit, and that prevention of denervation by IGF-1 overexpression would prevent external Ca(2+)-dependent contraction in aging mice. IGF-1 overexpression in skeletal muscle prevents age-related denervation, and prevented external Ca(2+)-dependent contraction in this work. To determine if the effects of IGF-1 overexpression are on muscle or nerve, aging mice were injected with a tetanus toxin fragment-C (TTC) fusion protein that targets IGF-1 to spinal cord motor neurons. This treatment prevented external Ca(2+)-dependent contraction. We also show evidence that injections of the IGF-1-TTC fusion protein prevent age-related alterations to the nerve terminals at the neuromuscular junctions. We conclude that the slow age-related denervation of fast muscle fibers underlies dependence on external Ca(2+) to maintain tetanic force in a population of muscle fibers from senescent mice.
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Affiliation(s)
- Anthony M. Payne
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - María Laura Messi
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Zhenlin Zheng
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
| | - Osvaldo Delbono
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
- Department of Internal Medicine, Section on Gerontology, Wake Forest University School of Medicine, Winston-Salem, NC 27157
- Neuroscience Program, Wake Forest University School of Medicine, Winston-Salem, NC 27157
- * Corresponding Author: Osvaldo Delbono, Department of Physiology and Pharmacology, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC 27157, USA, Phone: (336) 716-9802, Fax: (336) 716-2273,
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Carrington JL, Bellino FL. Developing a research agenda in biogerontology: physiological systems. SCIENCE OF AGING KNOWLEDGE ENVIRONMENT : SAGE KE 2006; 2006:pe17. [PMID: 16807481 DOI: 10.1126/sageke.2006.10.pe17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Biology of Aging Program (BAP) at the National Institute on Aging supports research in many areas, including processes of cell senescence and apoptosis, genetic influences on aging, and how aging leads to tissue dysfunction. Several approaches to research on aging physiological systems are described, along with BAP programmatic efforts to enhance and support that research. Understanding the relation between aging and tissue dysfunction has led to new insights into how health can be improved for aged individuals.
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Affiliation(s)
- Jill L Carrington
- Biology of Aging Program, National Institute on Aging, Bethesda, MD 20892, USA.
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Payne AM, Zheng Z, Messi ML, Milligan CE, González E, Delbono O. Motor neurone targeting of IGF-1 prevents specific force decline in ageing mouse muscle. J Physiol 2005; 570:283-94. [PMID: 16293644 PMCID: PMC1464304 DOI: 10.1113/jphysiol.2005.100032] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
IGF-1 is a potent growth factor for both motor neurones and skeletal muscle. Muscle IGF-1 is known to provide target-derived trophic effects on motor neurones. Therefore, IGF-1 overexpression in muscle is effective in delaying or preventing deleterious effects of ageing in both tissues. Since age-related decline in muscle function stems partly from motor neurone loss, a tetanus toxin fragment-C (TTC) fusion protein was created to target IGF-1 to motor neurones. IGF-1-TTC retains IGF-1 activity as indicated by [(3)H]thymidine incorporation into L6 myoblasts. Spinal cord motor neurones effectively bound and internalized the IGF-1-TTC in vitro. Similarly, IGF-1-TTC injected into skeletal muscles was taken up and retrogradely transported to the spinal cord in vivo, a process prevented by denervation of injected muscles. Three monthly IGF-1-TTC injections into muscles of ageing mice did not increase muscle weight or muscle fibre size, but significantly increased single fibre specific force over aged controls injected with saline, IGF-1, or TTC. None of the injections changed muscle fibre type composition, but neuromuscular junction post-terminals were larger and more complex in muscle fibres injected with IGF-1-TTC, compared to the other groups, suggesting preservation of muscle fibre innervation. This work demonstrates that induced overexpression of IGF-1 in spinal cord motor neurones of ageing mice prevents muscle fibre specific force decline, a hallmark of ageing skeletal muscle.
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Affiliation(s)
- Anthony M Payne
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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