1
|
Arnold WD, Clark BC. Neuromuscular junction transmission failure in aging and sarcopenia: The nexus of the neurological and muscular systems. Ageing Res Rev 2023; 89:101966. [PMID: 37270145 PMCID: PMC10847753 DOI: 10.1016/j.arr.2023.101966] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/05/2023] [Accepted: 05/29/2023] [Indexed: 06/05/2023]
Abstract
Sarcopenia, or age-related decline in muscle form and function, exerts high personal, societal, and economic burdens when untreated. Integrity and function of the neuromuscular junction (NMJ), as the nexus between the nervous and muscular systems, is critical for input and dependable neural control of muscle force generation. As such, the NMJ has long been a site of keen interest in the context of skeletal muscle function deficits during aging and in the context of sarcopenia. Historically, changes of NMJ morphology during aging have been investigated extensively but primarily in aged rodent models. Aged rodents have consistently shown features of NMJ endplate fragmentation and denervation. Yet, the presence of NMJ changes in older humans remains controversial, and conflicting findings have been reported. This review article describes the physiological processes involved in NMJ transmission, discusses the evidence that supports NMJ transmission failure as a possible contributor to sarcopenia, and speculates on the potential of targeting these defects for therapeutic development. The technical approaches that are available for assessment of NMJ transmission, whether each approach has been applied in the context of aging and sarcopenia, and the associated findings are summarized. Like morphological studies, age-related NMJ transmission deficits have primarily been studied in rodents. In preclinical studies, isolated synaptic electrophysiology recordings of endplate currents or potentials have been mostly used, and paradoxically, have shown enhancement, rather than failure, with aging. Yet, in vivo assessment of single muscle fiber action potential generation using single fiber electromyography and nerve-stimulated muscle force measurements show evidence of NMJ failure in aged mice and rats. Together these findings suggest that endplate response enhancement may be a compensatory response to post-synaptic mechanisms of NMJ transmission failure in aged rodents. Possible, but underexplored, mechanisms of this failure are discussed including the simplification of post-synaptic folding and altered voltage-gated sodium channel clustering or function. In humans, there is limited clinical data that has selectively investigated single synaptic function in the context of aging. If sarcopenic older adults turn out to exhibit notable impairments in NMJ transmission (this has yet to be examined but based on available evidence appears to be plausible) then these NMJ transmission defects present a well-defined biological mechanism and offer a well-defined pathway for clinical implementation. Investigation of small molecules that are currently available clinically or being testing clinically in other disorders may provide a rapid route for development of interventions for older adults impacted by sarcopenia.
Collapse
Affiliation(s)
- W David Arnold
- NextGen Precision Health, University of Missouri System, Columbia, MO, USA; Department of Physical Medicine and Rehabilitation University of Missouri, Columbia, MO, USA.
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI) Ohio University, Athens, OH, USA; Department of Biomedical Sciences, Ohio University, Athens, OH, USA.
| |
Collapse
|
2
|
Chung T, Bopp T, Ward C, Notarangelo FM, Schwarcz R, Westbrook R, Xue Q, Walston J, Hoke A. Deletion of quinolinate phosphoribosyltransferase gene accelerates frailty phenotypes and neuromuscular decline with aging in a sex-specific pattern. Aging Cell 2023; 22:e13849. [PMID: 37078472 PMCID: PMC10352574 DOI: 10.1111/acel.13849] [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: 11/04/2022] [Revised: 03/28/2023] [Accepted: 03/30/2023] [Indexed: 04/21/2023] Open
Abstract
Decline in neuromuscular function with aging is known to be a major determinant of disability and all-cause mortality in late life. Despite the importance of the problem, the neurobiology of age-associated muscle weakness is poorly understood. In a previous report, we performed untargeted metabolomics on frail older adults and discovered prominent alteration in the kynurenine pathway, the major route of dietary tryptophan degradation that produces neurotoxic intermediate metabolites. We also showed that neurotoxic kynurenine pathway metabolites are correlated with increased frailty score. For the present study, we sought to further examine the neurobiology of these neurotoxic intermediates by utilizing a mouse model that has a deletion of the quinolinate phosphoribosyltransferase (QPRT) gene, a rate-limiting step of the kynurenine pathway. QPRT-/- mice have elevated neurotoxic quinolinic acid level in the nervous system throughout their lifespan. We found that QPRT-/- mice have accelerated declines in neuromuscular function in an age- and sex-specific manner compared to control strains. In addition, the QPRT-/- mice show premature signs of frailty and body composition changes that are typical for metabolic syndrome. Our findings suggest that the kynurenine pathway may play an important role in frailty and age-associated muscle weakness.
Collapse
Affiliation(s)
- Tae Chung
- Department of Physical Medicine and RehabilitationJohns Hopkins University School of MedicineBaltimoreMarylandUSA
- Department of NeurologyNeuromuscular DivisionJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Taylor Bopp
- Department of Physical Medicine and RehabilitationJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Chris Ward
- Department of OrthopedicsUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Francesca M. Notarangelo
- Maryland Psychiatric Research CenterDepartment of PsychiatryUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Robert Schwarcz
- Maryland Psychiatric Research CenterDepartment of PsychiatryUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Reyhan Westbrook
- Department of Geriatric Medicine and GerontologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Qian‐Li Xue
- Department of Geriatric Medicine and GerontologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Jeremy Walston
- Department of Geriatric Medicine and GerontologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Ahmet Hoke
- Department of NeurologyNeuromuscular DivisionJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| |
Collapse
|
3
|
Ozes B, Tong L, Myers M, Moss K, Ridgley A, Sahenk Z. AAV1.NT-3 gene therapy prevents age-related sarcopenia. Aging (Albany NY) 2023; 15:1306-1329. [PMID: 36897179 PMCID: PMC10042697 DOI: 10.18632/aging.204577] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 03/02/2023] [Indexed: 03/11/2023]
Abstract
Sarcopenia is progressive loss of muscle mass and strength, occurring during normal aging with significant consequences on the quality of life for elderly. Neurotrophin 3 (NT-3) is an important autocrine factor supporting Schwann cell survival and differentiation and stimulating axon regeneration and myelination. NT-3 is involved in the maintenance of neuromuscular junction (NMJ) integrity, restoration of impaired radial growth of muscle fibers through activation of the Akt/mTOR pathway. We tested the efficacy of NT-3 gene transfer therapy in wild type (WT)-aged C57BL/6 mice, a model for natural aging and sarcopenia, via intramuscular injection 1 × 1011 vg AAV1.tMCK.NT-3, at 18 months of age. The treatment efficacy was assessed at 6 months post-injection using run to exhaustion and rotarod tests, in vivo muscle contractility assay, and histopathological studies of the peripheral nervous system, including NMJ connectivity and muscle. AAV1.NT-3 gene therapy in WT-aged C57BL/6 mice resulted in functional and in vivo muscle physiology improvements, supported by quantitative histology from muscle, peripheral nerves and NMJ. Hindlimb and forelimb muscles in the untreated cohort showed the presence of a muscle- and sex-dependent remodeling and fiber size decrease with aging, which was normalized toward values obtained from 10 months old WT mice with treatment. The molecular studies assessing the NT-3 effect on the oxidative state of distal hindlimb muscles, accompanied by western blot analyses for mTORC1 activation were in accordance with the histological findings. Considering the cost and quality of life to the individual, we believe our study has important implications for management of age-related sarcopenia.
Collapse
Affiliation(s)
- Burcak Ozes
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Lingying Tong
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Morgan Myers
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Kyle Moss
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Alicia Ridgley
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Zarife Sahenk
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA
- Department of Pediatrics and Neurology, Nationwide Children’s Hospital and The Ohio State University, Columbus, OH 43205, USA
- Department of Pathology and Laboratory Medicine, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| |
Collapse
|
4
|
Fogarty MJ, Sieck GC. Aging affects the number and morphological heterogeneity of rat phrenic motor neurons and phrenic motor axons. Physiol Rep 2023; 11:e15587. [PMID: 36695744 PMCID: PMC9875821 DOI: 10.14814/phy2.15587] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/26/2023] Open
Abstract
Diaphragm muscle (DIAm) motor units comprise a phrenic motor neuron (PhMN), the phrenic nerve and the muscle fibers innervated, with the size of PhMNs and axons characteristic of motor unit type. Smaller PhMNs and their axons comprise slow (type S) and fatigue-resistant (type FR) DIAm motor units, while larger PhMNs and their axons comprise more fatigable (type FF) motor units. With aging, we have shown a loss of larger PhMNs, consistent with selective atrophy of type IIx/IIb DIAm fibers and reduced maximum DIAm force. In the present study, we hypothesized that with aging there is a loss of larger myelinated phrenic α motor axons. Female and male young (6 months) and old (24 months) Fischer 344 rats were studied. PhMNs were retrogradely labeled by intrapleural injection of 488-conjugated CTB. The phrenic nerves were excised ~1 cm from the DIAm insertion and mounted in resin, and phrenic α motor axons were delineated based on size (i.e., >4 μm diameters). In older rats, the number of larger PhMNs and larger phrenic α motor axons were reduced. There were no differences in non-α axons. In addition, there was evidence of demyelination of larger phrenic α motor axons in older rats. Together, these findings are consistent with the selective age-related vulnerability of larger PhMNs and denervation of type FF motor units, which may underlie DIAm sarcopenia.
Collapse
Affiliation(s)
- Matthew J. Fogarty
- Department of Physiology & Biomedical EngineeringMayo ClinicRochesterMinnesotaUSA
| | - Gary C. Sieck
- Department of Physiology & Biomedical EngineeringMayo ClinicRochesterMinnesotaUSA
| |
Collapse
|
5
|
Cahalan SD, Boehm I, Jones RA, Piercy RJ. Recognising the potential of large animals for modelling neuromuscular junction physiology and disease. J Anat 2022; 241:1120-1132. [PMID: 36056593 PMCID: PMC9558152 DOI: 10.1111/joa.13749] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 12/28/2022] Open
Abstract
The aetiology and pathophysiology of many diseases of the motor unit remain poorly understood and the role of the neuromuscular junction (NMJ) in this group of disorders is particularly overlooked, especially in humans, when these diseases are comparatively rare. However, elucidating the development, function and degeneration of the NMJ is essential to uncover its contribution to neuromuscular disorders, and to explore potential therapeutic avenues to treat these devastating diseases. Until now, an understanding of the role of the NMJ in disease pathogenesis has been hindered by inherent differences between rodent and human NMJs: stark contrasts in body size and corresponding differences in associated axon length underpin some of the translational issues in animal models of neuromuscular disease. Comparative studies in large mammalian models, including examination of naturally occurring, highly prevalent animal diseases and evaluation of their treatment, might provide more relevant insights into the pathogenesis and therapy of equivalent human diseases. This review argues that large animal models offer great potential to enhance our understanding of the neuromuscular system in health and disease, and in particular, when dealing with diseases for which nerve length dependency might underly the pathogenesis.
Collapse
Affiliation(s)
- Stephen D Cahalan
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, Royal Veterinary College, University of London, London, UK
| | - Ines Boehm
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Biozentrum University of Basel, Basel, Switzerland
| | - Ross A Jones
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - Richard J Piercy
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, Royal Veterinary College, University of London, London, UK
| |
Collapse
|
6
|
Moss KR, Johnson AE, Bopp TS, Yu ATY, Perry K, Chung T, Höke A. SARM1 knockout does not rescue neuromuscular phenotypes in a Charcot-Marie-Tooth disease Type 1A mouse model. J Peripher Nerv Syst 2022; 27:58-66. [PMID: 35137510 PMCID: PMC8940700 DOI: 10.1111/jns.12483] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 01/25/2022] [Accepted: 02/02/2022] [Indexed: 11/28/2022]
Abstract
Charcot-Marie-Tooth disease Type 1A (CMT1A) is caused by duplication of the PMP22 gene and is the most common inherited peripheral neuropathy. Although CMT1A is a dysmyelinating peripheral neuropathy, secondary axon degeneration has been suggested to drive functional deficits in patients. Given that SARM1 knockout is a potent inhibitor of the programmed axon degeneration pathway, we asked whether SARM1 knockout rescues neuromuscular phenotypes in CMT1A model (C3-PMP) mice. CMT1A mice were bred with SARM1 knockout mice to generate CMT1A/SARM1-/- mice. A series of behavioral assays were employed to evaluate motor and sensorimotor function. Electrophysiological and histological studies of the tibial branch of the sciatic nerve were performed. Additionally, gastrocnemius and soleus muscle morphology were evaluated histologically. Although clear behavioral and electrophysiological deficits were observed in CMT1A model mice, genetic deletion of SARM1 conferred no significant improvement. Nerve morphometry revealed predominantly myelin deficits in CMT1A model mice and SARM1 knockout yielded no improvement in all nerve morphometry measures. Similarly, muscle morphometry deficits in CMT1A model mice were not improved by SARM1 knockout. Our findings demonstrate that programmed axon degeneration pathway inhibition does not provide therapeutic benefit in C3-PMP CMT1A model mice. Our results indicate that the clinical phenotypes observed in CMT1A mice are likely caused primarily by prolonged dysmyelination, motivate further investigation into mechanisms of dysmyelination in these mice and necessitate the development of improved CMT1A rodent models that recapitulate the secondary axon degeneration observed in patients.
Collapse
Affiliation(s)
- Kathryn R. Moss
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD
| | - Anna E. Johnson
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD
| | - Taylor S. Bopp
- Department of Physical Medicine and Rehabilitation, Johns Hopkins School of Medicine, Baltimore, MD
| | - Andrew T-Y. Yu
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD
| | - Ken Perry
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD
| | - Tae Chung
- Department of Physical Medicine and Rehabilitation, Johns Hopkins School of Medicine, Baltimore, MD
| | - Ahmet Höke
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD,Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD,Corresponding Author: Ahmet Höke MD, PhD, Johns Hopkins School of Medicine, 855 N. Wolfe St., Baltimore, MD 21205, Tel: 410-955-2227, Fax: 410-502-5459,
| |
Collapse
|
7
|
Ikemoto‐Uezumi M, Zhou H, Kurosawa T, Yoshimoto Y, Toyoda M, Kanazawa N, Nakazawa T, Morita M, Tsuchida K, Uezumi A. Increased MFG-E8 at neuromuscular junctions is an exacerbating factor for sarcopenia-associated denervation. Aging Cell 2022; 21:e13536. [PMID: 34953020 PMCID: PMC8761010 DOI: 10.1111/acel.13536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/11/2021] [Accepted: 11/30/2021] [Indexed: 11/28/2022] Open
Abstract
Sarcopenia is an important health problem associated with adverse outcomes. Although the etiology of sarcopenia remains poorly understood, factors apart from muscle fibers, including humoral factors, might be involved. Here, we used cytokine antibody arrays to identify humoral factors involved in sarcopenia and found a significant increase in levels of milk fat globule epidermal growth factor 8 (MFG‐E8) in skeletal muscle of aged mice, compared with young mice. We found that the increase in MFG‐E8 protein at arterial walls and neuromuscular junctions (NMJs) in muscles of aged mice. High levels of MFG‐E8 at NMJs and an age‐related increase in arterial MFG‐E8 have also been identified in human skeletal muscle. In NMJs, MFG‐E8 is localized on the surface of terminal Schwann cells, which are important accessory cells for the maintenance of NMJs. We found that increased MFG‐E8 at NMJs precedes age‐related denervation and is more prominent in sarcopenia‐susceptible fast‐twitch than in sarcopenia‐resistant slow‐twitch muscle. Comparison between fast and slow muscles further revealed that arterial MFG‐E8 can be uncoupled from sarcopenic phenotype. A genetic deficiency in MFG‐E8 attenuated age‐related denervation of NMJs and muscle weakness, providing evidence of a pathogenic role of increased MFG‐E8. Thus, our study revealed a mechanism by which increased MFG‐E8 at NMJs leads to age‐related NMJ degeneration and suggests that targeting MFG‐E8 could be a promising therapeutic approach to prevent sarcopenia.
Collapse
Affiliation(s)
- Madoka Ikemoto‐Uezumi
- Muscle Aging and Regenerative Medicine Tokyo Metropolitan Institute of Gerontology (TMIG) Tokyo Japan
| | - Heying Zhou
- Muscle Aging and Regenerative Medicine Tokyo Metropolitan Institute of Gerontology (TMIG) Tokyo Japan
| | - Tamaki Kurosawa
- Muscle Aging and Regenerative Medicine Tokyo Metropolitan Institute of Gerontology (TMIG) Tokyo Japan
- Laboratory of Veterinary Pharmacology Department of Veterinary Medical Sciences Graduate School of Agriculture and Life Sciences Tokyo University Tokyo Japan
| | - Yuki Yoshimoto
- Muscle Aging and Regenerative Medicine Tokyo Metropolitan Institute of Gerontology (TMIG) Tokyo Japan
| | | | - Nobuo Kanazawa
- Department of Surgery Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology Tokyo Japan
| | | | - Mitsuhiro Morita
- Department of Orthopaedic Surgery Fujita Health University Toyoake Japan
| | - Kunihiro Tsuchida
- Division for Therapies against Intractable Diseases Institute for Comprehensive Medical Science Fujita Health University Toyoake Japan
| | - Akiyoshi Uezumi
- Muscle Aging and Regenerative Medicine Tokyo Metropolitan Institute of Gerontology (TMIG) Tokyo Japan
| |
Collapse
|
8
|
Wilburn D, Ismaeel A, Machek S, Fletcher E, Koutakis P. Shared and distinct mechanisms of skeletal muscle atrophy: A narrative review. Ageing Res Rev 2021; 71:101463. [PMID: 34534682 DOI: 10.1016/j.arr.2021.101463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/30/2021] [Accepted: 09/11/2021] [Indexed: 12/15/2022]
Abstract
Maintenance of skeletal muscle mass and function is an incredibly nuanced balance of anabolism and catabolism that can become distorted within different pathological conditions. In this paper we intend to discuss the distinct intracellular signaling events that regulate muscle protein atrophy for a given clinical occurrence. Aside from the common outcome of muscle deterioration, several conditions have at least one or more distinct mechanisms that creates unique intracellular environments that facilitate muscle loss. The subtle individuality to each of these given pathologies can provide both researchers and clinicians with specific targets of interest to further identify and increase the efficacy of medical treatments and interventions.
Collapse
Affiliation(s)
- Dylan Wilburn
- Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX 76706, USA
| | - Ahmed Ismaeel
- Department of Biology, Baylor University, Waco, TX 76706, USA
| | - Steven Machek
- Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX 76706, USA
| | - Emma Fletcher
- Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX 76706, USA; Department of Biology, Baylor University, Waco, TX 76706, USA
| | | |
Collapse
|
9
|
Gras S, Blasco A, Mòdol-Caballero G, Tarabal O, Casanovas A, Piedrafita L, Barranco A, Das T, Rueda R, Pereira SL, Navarro X, Esquerda JE, Calderó J. Beneficial effects of dietary supplementation with green tea catechins and cocoa flavanols on aging-related regressive changes in the mouse neuromuscular system. Aging (Albany NY) 2021; 13:18051-18093. [PMID: 34319911 PMCID: PMC8351677 DOI: 10.18632/aging.203336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/19/2021] [Indexed: 12/17/2022]
Abstract
Besides skeletal muscle wasting, sarcopenia entails morphological and molecular changes in distinct components of the neuromuscular system, including spinal cord motoneurons (MNs) and neuromuscular junctions (NMJs); moreover, noticeable microgliosis has also been observed around aged MNs. Here we examined the impact of two flavonoid-enriched diets containing either green tea extract (GTE) catechins or cocoa flavanols on age-associated regressive changes in the neuromuscular system of C57BL/6J mice. Compared to control mice, GTE- and cocoa-supplementation significantly improved the survival rate of mice, reduced the proportion of fibers with lipofuscin aggregates and central nuclei, and increased the density of satellite cells in skeletal muscles. Additionally, both supplements significantly augmented the number of innervated NMJs and their degree of maturity compared to controls. GTE, but not cocoa, prominently increased the density of VAChT and VGluT2 afferent synapses on MNs, which were lost in control aged spinal cords; conversely, cocoa, but not GTE, significantly augmented the proportion of VGluT1 afferent synapses on aged MNs. Moreover, GTE, but not cocoa, reduced aging-associated microgliosis and increased the proportion of neuroprotective microglial phenotypes. Our data indicate that certain plant flavonoids may be beneficial in the nutritional management of age-related deterioration of the neuromuscular system.
Collapse
Affiliation(s)
- Sílvia Gras
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Alba Blasco
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Guillem Mòdol-Caballero
- Grup de Neuroplasticitat i Regeneració, Institut de Neurociències, Departament de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona and CIBERNED, Bellaterra, Spain
| | - Olga Tarabal
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Anna Casanovas
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Lídia Piedrafita
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Alejandro Barranco
- Department of Biochemistry and Molecular Biology II, School of Pharmacy, University of Granada, Granada, Spain
| | - Tapas Das
- Abbott Nutrition, Research and Development, Columbus, OH 43215, USA
| | - Ricardo Rueda
- Abbott Nutrition, Research and Development, Granada, Spain
| | | | - Xavier Navarro
- Grup de Neuroplasticitat i Regeneració, Institut de Neurociències, Departament de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona and CIBERNED, Bellaterra, Spain
| | - Josep E. Esquerda
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Jordi Calderó
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| |
Collapse
|
10
|
Sugita S, Tamura K, Yano M, Minegishi Y, Ota N. The Impact of Milk Fat Globule Membrane with Exercise on Age-Related Degeneration of Neuromuscular Junctions. Nutrients 2021; 13:nu13072310. [PMID: 34371820 PMCID: PMC8308682 DOI: 10.3390/nu13072310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 12/19/2022] Open
Abstract
Morphological changes in neuromuscular junctions (NMJs), which are synapses formed between α-motor neurons and skeletal muscle fibers, are considered to be important in age-related motor dysfunction. We have previously shown that the intake of dietary milk fat globule membrane (MFGM) combined with exercise attenuates age-related NMJ alterations in the early phase of aging. However, it is unclear whether the effect of MFGM with exercise on age-related NMJ alterations persists into old age, and whether intervention from old age is still effective when age-related changes in NMJs have already occurred. In this study, 6- or 18-month-old mice were treated with a 1% MFGM diet and daily running wheel exercise until 23 or 24 months of age, respectively. MFGM treatment with exercise was effective in suppressing the progression of age-related NMJ alterations in old age, and even after age-related changes in NMJs had already occurred. Moreover, the effect of MFGM intake with exercise was not restricted to NMJs but extended to the structure and function of peripheral nerves. This study demonstrates that MFGM intake with exercise may be a novel approach for improving motor function in the elderly by suppressing age-related NMJ alterations.
Collapse
|
11
|
Allen MD, Dalton BH, Gilmore KJ, McNeil CJ, Doherty TJ, Rice CL, Power GA. Neuroprotective effects of exercise on the aging human neuromuscular system. Exp Gerontol 2021; 152:111465. [PMID: 34224847 DOI: 10.1016/j.exger.2021.111465] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 05/31/2021] [Accepted: 06/30/2021] [Indexed: 12/23/2022]
Abstract
Human biological aging from maturity to senescence is associated with a gradual loss of muscle mass and neuromuscular function. It is not until very old age (>80 years) however, that these changes often manifest into functional impairments. A driving factor underlying the age-related loss of muscle mass and function is the reduction in the number and quality of motor units (MUs). A MU consists of a single motoneuron, located either in the spinal cord or the brain stem, and all of the muscle fibres it innervates via its peripheral axon. Throughout the adult lifespan, MUs are slowly, but progressively lost. The compensatory process of collateral reinnervation attempts to recapture orphaned muscle fibres following the death of a motoneuron. Whereas this process helps mitigate loss of muscle mass during the latter decades of adult aging, the neuromuscular system has fewer and larger MUs, which have lower quality connections between the axon terminal and innervated muscle fibres. Whether this process of MU death and degradation can be attenuated with habitual physical activity has been a challenging question of great interest. This review focuses on age-related alterations of the human neuromuscular system, with an emphasis on the MU, and presents findings on the potential protective effects of lifelong physical activity. Although there is some discrepancy across studies of masters athletes, if one considers all experimental limitations as well as the available literature in animals, there is compelling evidence of a protective effect of chronic physical training on human MUs. Our tenet is that high-levels of physical activity can mitigate the natural trajectory of loss of quantity and quality of MUs in old age.
Collapse
Affiliation(s)
- Matti D Allen
- Department of Physical Medicine and Rehabilitation, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON K7L 4X3, Canada; School of Kinesiology and Health Studies, Faculty of Arts and Sciences, Queen's University, Kingston, ON K7L 4X3, Canada
| | - Brian H Dalton
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC V1V 1V7, Canada
| | - Kevin J Gilmore
- Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Chris J McNeil
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC V1V 1V7, Canada
| | - Timothy J Doherty
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada; Department of Physical Medicine and Rehabilitation, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
| | - Charles L Rice
- School of Kinesiology, The University of Western Ontario, London, ON, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| |
Collapse
|
12
|
Fuertes-Alvarez S, Izeta A. Terminal Schwann Cell Aging: Implications for Age-Associated Neuromuscular Dysfunction. Aging Dis 2021; 12:494-514. [PMID: 33815879 PMCID: PMC7990373 DOI: 10.14336/ad.2020.0708] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/08/2020] [Indexed: 12/11/2022] Open
Abstract
Action potential is transmitted to muscle fibers through specialized synaptic interfaces called neuromuscular junctions (NMJs). These structures are capped by terminal Schwann cells (tSCs), which play essential roles during formation and maintenance of the NMJ. tSCs are implicated in the correct communication between nerves and muscles, and in reinnervation upon injury. During aging, loss of muscle mass and strength (sarcopenia and dynapenia) are due, at least in part, to the progressive loss of contacts between muscle fibers and nerves. Despite the important role of tSCs in NMJ function, very little is known on their implication in the NMJ-aging process and in age-associated denervation. This review summarizes the current knowledge about the implication of tSCs in the age-associated degeneration of NMJs. We also speculate on the possible mechanisms underlying the observed phenotypes.
Collapse
Affiliation(s)
- Sandra Fuertes-Alvarez
- 1Biodonostia, Tissue Engineering Group, Paseo Dr. Begiristain, s/n, San Sebastian 20014, Spain
| | - Ander Izeta
- 1Biodonostia, Tissue Engineering Group, Paseo Dr. Begiristain, s/n, San Sebastian 20014, Spain.,2Tecnun-University of Navarra, School of Engineering, Department of Biomedical Engineering and Science, Paseo Mikeletegi, 48, San Sebastian 20009, Spain
| |
Collapse
|
13
|
Prokop A. A common theme for axonopathies? The dependency cycle of local axon homeostasis. Cytoskeleton (Hoboken) 2021; 78:52-63. [PMID: 33713552 DOI: 10.1002/cm.21657] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 12/12/2022]
Abstract
The number of acquired or inherited conditions leading to axon degeneration (from now on referred to as axonopathies) is vast. To diagnose patients, clinicians use a range of indicators including physiology, morphology, family and patient history, as well as genetics, with the specific location of the lesion within the nervous system being a prominent feature. For the neurobiologist, these criteria are often unsatisfactory, and key questions remain unanswered. For example, does it make sense that different axonopathies affect distinct neuron groups through distinct mechanisms? Would it not be more likely that there are common routes to axon degeneration? In this opinion piece, I shall pose this fundamental question and try to find answers that are hopefully thought-provoking and trigger some conceptual rethinking in the field. I will conclude by describing the 'dependency cycle of axon homeostasis' as a new approach to make sense of the intricate connections of axon biology and physiology, also suggesting that different axonopathies might share common paths to axon degeneration.
Collapse
Affiliation(s)
- Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, The University of Manchester, Manchester, UK
| |
Collapse
|
14
|
Dewolf AH, Sylos-Labini F, Cappellini G, Ivanenko Y, Lacquaniti F. Age-related changes in the neuromuscular control of forward and backward locomotion. PLoS One 2021; 16:e0246372. [PMID: 33596223 PMCID: PMC7888655 DOI: 10.1371/journal.pone.0246372] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/18/2021] [Indexed: 01/14/2023] Open
Abstract
Previous studies found significant modification in spatiotemporal parameters of backward walking in healthy older adults, but the age-related changes in the neuromuscular control have been considered to a lesser extent. The present study compared the intersegmental coordination, muscle activity and corresponding modifications of spinal montoneuronal output during both forward and backward walking in young and older adults. Ten older and ten young adults walked forward and backward on a treadmill at different speeds. Gait kinematics and EMG activity of 14 unilateral lower-limb muscles were recorded. As compared to young adults, the older ones used shorter steps, a more in-phase shank and foot motion, and the activity profiles of muscles innervated from the sacral segments were significantly wider in each walking condition. These findings highlight age-related changes in the neuromuscular control of both forward and backward walking. A striking feature of backward walking was the differential organization of the spinal output as compared to forward gait. In addition, the resulting spatiotemporal map patterns also characterized age-related changes of gait. Finally, modifications of the intersegmental coordination with aging were greater during backward walking. On the whole, the assessment of backward walk in addition to routine forward walk may help identifying or unmasking neuromuscular adjustments of gait to aging.
Collapse
Affiliation(s)
- Arthur H. Dewolf
- Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, Rome, Italy
- * E-mail:
| | | | - Germana Cappellini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
- Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Francesco Lacquaniti
- Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, Rome, Italy
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
| |
Collapse
|
15
|
Marshall KL, Farah MH. Axonal regeneration and sprouting as a potential therapeutic target for nervous system disorders. Neural Regen Res 2021; 16:1901-1910. [PMID: 33642358 PMCID: PMC8343323 DOI: 10.4103/1673-5374.308077] [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] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Nervous system disorders are prevalent health issues that will only continue to increase in frequency as the population ages. Dying-back axonopathy is a hallmark of many neurologic diseases and leads to axonal disconnection from their targets, which in turn leads to functional impairment. During the course of many of neurologic diseases, axons can regenerate or sprout in an attempt to reconnect with the target and restore synapse function. In amyotrophic lateral sclerosis (ALS), distal motor axons retract from neuromuscular junctions early in the disease-course before significant motor neuron death. There is evidence of compensatory motor axon sprouting and reinnervation of neuromuscular junctions in ALS that is usually quickly overtaken by the disease course. Potential drugs that enhance compensatory sprouting and encourage reinnervation may slow symptom progression and retain muscle function for a longer period of time in ALS and in other diseases that exhibit dying-back axonopathy. There remain many outstanding questions as to the impact of distinct disease-causing mutations on axonal outgrowth and regeneration, especially in regards to motor neurons derived from patient induced pluripotent stem cells. Compartmentalized microfluidic chambers are powerful tools for studying the distal axons of human induced pluripotent stem cells-derived motor neurons, and have recently been used to demonstrate striking regeneration defects in human motor neurons harboring ALS disease-causing mutations. Modeling the human neuromuscular circuit with human induced pluripotent stem cells-derived motor neurons will be critical for developing drugs that enhance axonal regeneration, sprouting, and reinnervation of neuromuscular junctions. In this review we will discuss compensatory axonal sprouting as a potential therapeutic target for ALS, and the use of compartmentalized microfluidic devices to find drugs that enhance regeneration and axonal sprouting of motor axons.
Collapse
Affiliation(s)
| | - Mohamed H Farah
- Department of Neurology at Johns Hopkins School of Medicine, Baltimore, MD, USA
| |
Collapse
|
16
|
Blasco A, Gras S, Mòdol-Caballero G, Tarabal O, Casanovas A, Piedrafita L, Barranco A, Das T, Pereira SL, Navarro X, Rueda R, Esquerda JE, Calderó J. Motoneuron deafferentation and gliosis occur in association with neuromuscular regressive changes during ageing in mice. J Cachexia Sarcopenia Muscle 2020; 11:1628-1660. [PMID: 32691534 PMCID: PMC7749545 DOI: 10.1002/jcsm.12599] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/05/2020] [Accepted: 06/15/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The cellular mechanisms underlying the age-associated loss of muscle mass and function (sarcopenia) are poorly understood, hampering the development of effective treatment strategies. Here, we performed a detailed characterization of age-related pathophysiological changes in the mouse neuromuscular system. METHODS Young, adult, middle-aged, and old (1, 4, 14, and 24-30 months old, respectively) C57BL/6J mice were used. Motor behavioural and electrophysiological tests and histological and immunocytochemical procedures were carried out to simultaneously analyse structural, molecular, and functional age-related changes in distinct cellular components of the neuromuscular system. RESULTS Ageing was not accompanied by a significant loss of spinal motoneurons (MNs), although a proportion (~15%) of them in old mice exhibited an abnormally dark appearance. Dark MNs were also observed in adult (~9%) and young (~4%) animals, suggesting that during ageing, some MNs undergo early deleterious changes, which may not lead to MN death. Old MNs were depleted of cholinergic and glutamatergic inputs (~40% and ~45%, respectively, P < 0.01), suggestive of age-associated alterations in MN excitability. Prominent microgliosis and astrogliosis [~93% (P < 0.001) and ~100% (P < 0.0001) increase vs. adults, respectively] were found in old spinal cords, with increased density of pro-inflammatory M1 microglia and A1 astroglia (25-fold and 4-fold increase, respectively, P < 0.0001). Ageing resulted in significant reductions in the nerve conduction velocity and the compound muscle action potential amplitude (~30%, P < 0.05, vs. adults) in old distal plantar muscles. Compared with adult muscles, old muscles exhibited significantly higher numbers of both denervated and polyinnervated neuromuscular junctions, changes in fibre type composition, higher proportion of fibres showing central nuclei and lipofuscin aggregates, depletion of satellite cells, and augmented expression of different molecules related to development, plasticity, and maintenance of neuromuscular junctions, including calcitonin gene-related peptide, growth associated protein 43, agrin, fibroblast growth factor binding protein 1, and transforming growth factor-β1. Overall, these alterations occurred at varying degrees in all the muscles analysed, with no correlation between the age-related changes observed and myofiber type composition or muscle topography. CONCLUSIONS Our data provide a global view of age-associated neuromuscular changes in a mouse model of ageing and help to advance understanding of contributing pathways leading to development of sarcopenia.
Collapse
Affiliation(s)
- Alba Blasco
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Sílvia Gras
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Guillem Mòdol-Caballero
- Grup de Neuroplasticitat i Regeneració, Institut de Neurociències, Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, CIBERNED, Bellaterra, Spain
| | - Olga Tarabal
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Anna Casanovas
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Lídia Piedrafita
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | | | - Tapas Das
- Abbott Nutrition Research and Development, Columbus, OH, USA
| | | | - Xavier Navarro
- Grup de Neuroplasticitat i Regeneració, Institut de Neurociències, Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, CIBERNED, Bellaterra, Spain
| | - Ricardo Rueda
- Abbott Nutrition Research and Development, Granada, Spain
| | - Josep E Esquerda
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Jordi Calderó
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida, Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| |
Collapse
|
17
|
Giorgetti E, Panesar M, Zhang Y, Joller S, Ronco M, Obrecht M, Lambert C, Accart N, Beckmann N, Doelemeyer A, Perrot L, Fruh I, Mueller M, Pierrel E, Summermatter S, Bidinosti M, Shimshek DR, Brachat S, Nash M. Modulation of Microglia by Voluntary Exercise or CSF1R Inhibition Prevents Age-Related Loss of Functional Motor Units. Cell Rep 2020; 29:1539-1554.e7. [PMID: 31693894 DOI: 10.1016/j.celrep.2019.10.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 07/27/2019] [Accepted: 10/01/2019] [Indexed: 01/05/2023] Open
Abstract
Age-related loss of skeletal muscle innervation by motor neurons leads to impaired neuromuscular function and is a well-established clinical phenomenon. However, the underlying pathogenesis remains unclear. Studying mice, we find that the number of motor units (MUs) can be maintained by counteracting neurotoxic microglia in the aged spinal cord. We observe that marked innervation changes, detected by motor unit number estimation (MUNE), occur prior to loss of muscle function in aged mice. This coincides with gene expression changes indicative of neuronal remodeling and microglial activation in aged spinal cord. Voluntary exercise prevents loss of MUs and reverses microglia activation. Depleting microglia by CSF1R inhibition also prevents the age-related decline in MUNE and neuromuscular junction disruption, implying a causal link. Our results suggest that age-related changes in spinal cord microglia contribute to neuromuscular decline in aged mice and demonstrate that removal of aged neurotoxic microglia can prevent or reverse MU loss.
Collapse
Affiliation(s)
- Elisa Giorgetti
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland.
| | - Moh Panesar
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Yunyu Zhang
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, Cambridge, MA 02139, USA
| | - Stefanie Joller
- Neuroscience, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Marie Ronco
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Michael Obrecht
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Christian Lambert
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Nathalie Accart
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Nicolau Beckmann
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Arno Doelemeyer
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Ludovic Perrot
- Global Sci Operations, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Isabelle Fruh
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Matthias Mueller
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Eliane Pierrel
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Serge Summermatter
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Michael Bidinosti
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Derya R Shimshek
- Neuroscience, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Sophie Brachat
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Mark Nash
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland.
| |
Collapse
|
18
|
Castets P, Ham DJ, Rüegg MA. The TOR Pathway at the Neuromuscular Junction: More Than a Metabolic Player? Front Mol Neurosci 2020; 13:162. [PMID: 32982690 PMCID: PMC7485269 DOI: 10.3389/fnmol.2020.00162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022] Open
Abstract
The neuromuscular junction (NMJ) is the chemical synapse connecting motor neurons and skeletal muscle fibers. NMJs allow all voluntary movements, and ensure vital functions like breathing. Changes in the structure and function of NMJs are hallmarks of numerous pathological conditions that affect muscle function including sarcopenia, the age-related loss of muscle mass and function. However, the molecular mechanisms leading to the morphological and functional perturbations in the pre- and post-synaptic compartments of the NMJ remain poorly understood. Here, we discuss the role of the metabolic pathway associated to the kinase TOR (Target of Rapamycin) in the development, maintenance and alterations of the NMJ. This is of particular interest as the TOR pathway has been implicated in aging, but its role at the NMJ is still ill-defined. We highlight the respective functions of the two TOR-associated complexes, TORC1 and TORC2, and discuss the role of localized protein synthesis and autophagy regulation in motor neuron terminals and sub-synaptic regions of muscle fibers and their possible effects on NMJ maintenance.
Collapse
Affiliation(s)
- Perrine Castets
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | | | | |
Collapse
|
19
|
Westbrook R, Chung T, Lovett J, Ward C, Joca H, Yang H, Khadeer M, Tian J, Xue QL, Le A, Ferrucci L, Moaddel R, de Cabo R, Hoke A, Walston J, Abadir PM. Kynurenines link chronic inflammation to functional decline and physical frailty. JCI Insight 2020; 5:136091. [PMID: 32814718 PMCID: PMC7455140 DOI: 10.1172/jci.insight.136091] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 07/15/2020] [Indexed: 12/27/2022] Open
Abstract
Chronic inflammation is associated with physical frailty and functional decline in older adults; however, the molecular mechanisms of this linkage are not understood. A mouse model of chronic inflammation showed reduced motor function and partial denervation at the neuromuscular junction. Metabolomic profiling of these mice and further validation in frail human subjects showed significant dysregulation in the tryptophan degradation pathway, including decreased tryptophan and serotonin, and increased levels of some neurotoxic kynurenines. In humans, kynurenine strongly correlated with age, frailty status, TNF-αR1 and IL-6, weaker grip strength, and slower walking speed. To study the effects of elevated neurotoxic kynurenines on motor neuronal cell viability and axonal degeneration, we used motor neuronal cells treated with 3-hydroxykynurenine and quinolinic acid and observed neurite degeneration in a dose-dependent manner and potentiation of toxicity between 3-hydroxykynurenine and quinolinic acid. These results suggest that kynurenines mediate neuromuscular dysfunction associated with chronic inflammation and aging. Tryptophan-related toxic metabolites known as kynurenines are altered with chronic inflammation, which damages nerves in aged and frail mice and humans.
Collapse
Affiliation(s)
| | - Tae Chung
- Department of Physical Medicine and Rehabilitation, and.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Chris Ward
- Department of Orthopedics and Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Humberto Joca
- Department of Orthopedics and Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Huanle Yang
- Division of Geriatric Medicine and Gerontology
| | | | - Jing Tian
- Division of Geriatric Medicine and Gerontology
| | - Qian-Li Xue
- Division of Geriatric Medicine and Gerontology
| | - Anne Le
- Department of Oncology and.,Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Luigi Ferrucci
- National Institute on Aging, NIH, Baltimore, Maryland, USA
| | - Ruin Moaddel
- National Institute on Aging, NIH, Baltimore, Maryland, USA
| | - Rafa de Cabo
- National Institute on Aging, NIH, Baltimore, Maryland, USA
| | - Ahmet Hoke
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jeremy Walston
- Division of Geriatric Medicine and Gerontology.,Department of Medicine, Kyung Hee University, Seoul, South Korea
| | | |
Collapse
|
20
|
Programmed axon degeneration: from mouse to mechanism to medicine. Nat Rev Neurosci 2020; 21:183-196. [PMID: 32152523 DOI: 10.1038/s41583-020-0269-3] [Citation(s) in RCA: 169] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2020] [Indexed: 11/08/2022]
Abstract
Wallerian degeneration is a widespread mechanism of programmed axon degeneration. In the three decades since the discovery of the Wallerian degeneration slow (WldS) mouse, research has generated extensive knowledge of the molecular mechanisms underlying Wallerian degeneration, demonstrated its involvement in non-injury disorders and found multiple ways to block it. Recent developments have included: the detection of NMNAT2 mutations that implicate Wallerian degeneration in rare human diseases; the capacity for lifelong rescue of a lethal condition related to Wallerian degeneration in mice; the discovery of 'druggable' enzymes, including SARM1 and MYCBP2 (also known as PHR1), in Wallerian pathways; and the elucidation of protein structures to drive further understanding of the underlying mechanisms and drug development. Additionally, new data have indicated the potential of these advances to alleviate a number of common disorders, including chemotherapy-induced and diabetic peripheral neuropathies, traumatic brain injury, and amyotrophic lateral sclerosis.
Collapse
|
21
|
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.
Collapse
|
22
|
Tan KT, Ang STJ, Tsai SY. Sarcopenia: Tilting the Balance of Protein Homeostasis. Proteomics 2019; 20:e1800411. [PMID: 31722440 DOI: 10.1002/pmic.201800411] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 11/04/2019] [Indexed: 12/14/2022]
Abstract
Sarcopenia, defined as age-associated decline of muscle mass and function, is a risk factor for mortality and disability, and comorbid with several chronic diseases such as type II diabetes and cardiovascular diseases. Clinical trials showed that nutritional supplements had positive effects on muscle mass, but not on muscle function and strength, demonstrating our limited understanding of the molecular events involved in the ageing muscle. Protein homeostasis, the equilibrium between protein synthesis and degradation, is proposed as the major mechanism underlying the development of sarcopenia. As the key central regulator of protein homeostasis, the mammalian target of rapamycin (mTOR) is proposed to be essential for muscle hypertrophy. Paradoxically, sustained activation of mTOR complex 1 (mTORC1) is associated with a loss of sensitivity to extracellular signaling in the elderly. It is not understood why sustained mTORC1 activity, which should induce muscle hypertrophy, instead results in muscle atrophy. Here, recent findings on the implications of disrupting protein homeostasis on muscle physiology and sarcopenia development in the context of mTOR/protein kinase B (AKT) signaling are reviewed. Understanding the role of these molecular mechanisms during the ageing process will contribute towards the development of targeted therapies that will improve protein metabolism and reduce sarcopenia.
Collapse
Affiliation(s)
- Kuan Ting Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9 Admin Office, Singapore, 117597, Singapore
| | - Seok-Ting Jamie Ang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9 Admin Office, Singapore, 117597, Singapore
| | - Shih-Yin Tsai
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9 Admin Office, Singapore, 117597, Singapore
| |
Collapse
|
23
|
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: 23] [Impact Index Per Article: 4.6] [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.
Collapse
|
24
|
Wang AYL, Loh CYY, Shen HH, Hsieh SY, Wang IK, Chuang SH, Wei FC. Topical Application of Human Wharton's Jelly Mesenchymal Stem Cells Accelerates Mouse Sciatic Nerve Recovery and is Associated with Upregulated Neurotrophic Factor Expression. Cell Transplant 2019; 28:1560-1572. [PMID: 31565957 PMCID: PMC6923547 DOI: 10.1177/0963689719880543] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Peripheral nerve regeneration following injury is often slow and impaired, which results in weakened and denervated muscle with subsequent atrophy. Human Wharton's jelly mesenchymal stem cells (hWJ-MSC) have potential regenerative properties which, however, remain unknown in mouse nerve recovery. This study investigated the effect of the topical application of hWJ-MSC onto repairing transected sciatic nerves in a mouse model. Human adipocyte-derived stem cells (hADSC) were used as a positive control. The sciatic nerve of BALB/c mice was transected at a fixed point and repaired under the microscope using 10-0 sutures. hWJ-MSC and hADSC were applied to the site of repair and mice were followed up for 1 year. The hWJ-MSC group had significantly better functional recovery of five-toe spread and gait angles compared with the negative control and hADSC groups. hWJ-MSC improved sciatic nerve regeneration in a dose-dependent fashion. The hWJ-MSC group had a better quality of regenerated nerve with an increased number of myelinated axons throughout. hWJ-MSC appear to be safe in mice after 1 year of follow-up. hWJ-MSC also expressed higher levels of neurotrophic factor-3, brain-derived neurotrophic factor, and glial-derived neurotrophic factor than hADSC. hWJ-MSC may promote better nerve recovery than hADSC because of this upregulation of neurotrophic factors.
Collapse
Affiliation(s)
- Aline Yen Ling Wang
- Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | | | - Hsin-Hsin Shen
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Sing-Ying Hsieh
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Ing-Kae Wang
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Sheng-Hao Chuang
- Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Fu-Chan Wei
- Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan, Taiwan.,Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| |
Collapse
|
25
|
Increased Single-Fiber Jitter Level Is Associated With Reduction in Motor Function With Aging. Am J Phys Med Rehabil 2019; 97:551-556. [PMID: 29498943 DOI: 10.1097/phm.0000000000000915] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Age-associated skeletal muscle weakness is a major contributing factor to an increased late life mortality and morbidity, but its neurobiology is poorly understood. Previously, we provided histological evidence of dying-back axonal degeneration of motor neurons and denervation of neuromuscular junctions in age-associated muscle weakness. Given this, we aimed to evaluate the relation between impaired neuromuscular transmission and various aspects of age-associated muscle weakness. DESIGN We compared two electrophysiological measures, single-fiber jitter and compound motor action potential in mice of different age groups, and correlated them with various physical performance measures, such as grip strength, standing and walking time, and treadmill performance. RESULTS Consistent with our previous histological data, single-fiber jitter, a measure of neuromuscular junction transmission, was significantly increased in older animals, whereas compound motor action potential shows no difference between young and old age groups. Neither jitter nor compound motor action potential correlated with any of physical performance measures, except for jitter and standing activity. CONCLUSIONS Impaired neuromuscular transmission-represented as increase in single-fiber electromyography jitter level-reflects decline in motor function with aging.
Collapse
|
26
|
Truong PH, Ciccotosto GD, Cappai R. Analysis of Motor Function in Amyloid Precursor-Like Protein 2 Knockout Mice: The Effects of Ageing and Sex. Neurochem Res 2018; 44:1356-1366. [PMID: 30362021 DOI: 10.1007/s11064-018-2669-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/18/2018] [Accepted: 10/20/2018] [Indexed: 12/19/2022]
Abstract
The amyloid precursor protein (APP) is a member of a conserved gene family that includes the amyloid precursor-like proteins 1 (APLP1) and 2 (APLP2). APP and APLP2 share a high degree of similarity, and have overlapping patterns of spatial and temporal expression in the central and peripheral tissues, in particular at the neuromuscular junction. APP-family knockout (KO) studies have helped elucidate aspects of function and functional redundancy amongst the APP-family members. In the present study, we investigated motor performance of APLP2-KO mice and the effect sex differences and age-related changes have on motor performance. APLP2-KO and WT (on C57Bl6 background) littermates control mice from 8 (young adulthood) to 48 weeks (middle age) were investigated. Analysis of motor neuron and muscle morphology showed APLP2-KO females but not males, had less age-related motor function impairments. We observed age and sex differences in both motor neuron number and muscle fiber size distribution for APLP2-KO mice compared to WT (C57Bl6). These alterations in the motor neuron number and muscle fiber distribution pattern may explain why female APLP2-KO mice have far better motor function behaviour during ageing.
Collapse
Affiliation(s)
- Phan H Truong
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Giuseppe D Ciccotosto
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Roberto Cappai
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia.
| |
Collapse
|
27
|
Sheth KA, Iyer CC, Wier CG, Crum AE, Bratasz A, Kolb SJ, Clark BC, Burghes AHM, Arnold WD. Muscle strength and size are associated with motor unit connectivity in aged mice. Neurobiol Aging 2018; 67:128-136. [PMID: 29656012 PMCID: PMC5981861 DOI: 10.1016/j.neurobiolaging.2018.03.016] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 03/12/2018] [Accepted: 03/15/2018] [Indexed: 12/11/2022]
Abstract
In older adults, the loss of muscle strength (dynapenia) and the loss of muscle mass (sarcopenia) are important contributors to the loss of physical function. We sought to investigate dynapenia, sarcopenia, and the loss of motor unit function in aging mice. C57BL/6J mice were analyzed with cross-sectional (males: 3 vs. 27 months; males and females: 8 vs. 12 vs. 20 months) and longitudinal studies (males: 10-25 months) using in vivo electrophysiological measures of motor unit connectivity (triceps surae compound muscle action potential and motor unit number estimation), in vivo measures of plantar flexion torque, magnetic resonance imaging of hind limb muscle volume, and grip strength. Compound muscle action potential amplitude, motor unit number estimation, and plantar flexion torque were decreased at 20 months. In contrast, grip strength was reduced at 24 months. Motor unit number estimates correlated with muscle torque and hind limb muscle volume. Our results demonstrate that the loss of motor unit connectivity is an early finding in aging male and female mice and that muscle size and contractility are both associated with motor unit number.
Collapse
Affiliation(s)
- Kajri A Sheth
- Department of Neurology, Ohio State University, Columbus, OH, USA
| | - Chitra C Iyer
- Department of Neurology, Ohio State University, Columbus, OH, USA; Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA
| | - Christopher G Wier
- Department of Neurology, Ohio State University, Columbus, OH, USA; Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA
| | - Alexander E Crum
- Department of Neurology, Ohio State University, Columbus, OH, USA
| | - Anna Bratasz
- Small Animal Imaging Core, Wexner Medical Center, Ohio State University, Columbus, OH, USA
| | - Stephen J Kolb
- Department of Neurology, Ohio State University, Columbus, OH, USA; Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA
| | - Arthur H M Burghes
- Department of Neurology, Ohio State University, Columbus, OH, USA; Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA
| | - W David Arnold
- Department of Neurology, Ohio State University, Columbus, OH, USA; Department of Physical Medicine and Rehabilitation, Ohio State University, Columbus, OH, USA; Department of Neuroscience, Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, Ohio State University, Columbus, OH, USA.
| |
Collapse
|
28
|
Chand KK, Lee KM, Lee JD, Qiu H, Willis EF, Lavidis NA, Hilliard MA, Noakes PG. Defects in synaptic transmission at the neuromuscular junction precede motor deficits in a TDP‐43
Q331K
transgenic mouse model of amyotrophic lateral sclerosis. FASEB J 2018; 32:2676-2689. [DOI: 10.1096/fj.201700835r] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kirat K. Chand
- School of Biomedical Sciences Brisbane Queensland Australia
| | - Kah Meng Lee
- School of Biomedical Sciences Brisbane Queensland Australia
| | - John D. Lee
- School of Biomedical Sciences Brisbane Queensland Australia
| | - Hao Qiu
- School of Biomedical Sciences Brisbane Queensland Australia
| | | | | | | | | |
Collapse
|