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Tsentsevitsky AN, Sibgatullina GV, Odoshivkina YG, Khuzakhmetova VF, Tokmakova AR, Ponomareva AA, Salnikov VV, Zakirjanova GF, Petrov AM, Bukharaeva EA. Functional and Structural Changes in Diaphragm Neuromuscular Junctions in Early Aging. Int J Mol Sci 2024; 25:8959. [PMID: 39201644 PMCID: PMC11354816 DOI: 10.3390/ijms25168959] [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: 07/24/2024] [Revised: 08/10/2024] [Accepted: 08/15/2024] [Indexed: 09/02/2024] Open
Abstract
Age-related impairment of the diaphragm causes respiratory complications. Neuromuscular junction (NMJ) dysfunction can be one of the triggering events in diaphragm weaknesses in old age. Prominent structural and functional alterations in diaphragm NMJs were described in elderly rodents, but NMJ changes in middle age remain unclear. Here, we compared diaphragm muscles from young adult (3 months) and middle-aged (12 months) BALB/c mice. Microelectrode recordings, immunofluorescent staining, electron microscopy, myography, and whole-body plethysmography were used. We revealed presynaptic (i) and postsynaptic (ii) changes. The former (i) included an increase in both action potential propagation velocity and neurotransmitter release evoked by low-, moderate-, and high-frequency activity but a decrease in immunoexpression of synapsin 1 and synaptic vesicle clustering. The latter (ii) consisted of a decrease in currents via nicotinic acetylcholine receptors and the area of their distribution. These NMJ changes correlated with increased contractile responses to moderate- to high-frequency nerve activation. Additionally, we found alterations in the pattern of respiration (an increase in peak inspiratory flow and a tendency of elevation of the tidal volume), which imply increased diaphragm activity in middle-aged mice. We conclude that enhancement of neuromuscular communication (due to presynaptic mechanism) accompanied by improved contractile responses occurs in the diaphragm in early aging.
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Affiliation(s)
- Andrei N. Tsentsevitsky
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
| | - Guzel V. Sibgatullina
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
| | - Yulia G. Odoshivkina
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
- Department of Normal Physiology, Kazan State Medical University, 49 Butlerova Street, 420012 Kazan, Russia
| | - Venera F. Khuzakhmetova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
| | - Anna R. Tokmakova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
| | - Anastasia A. Ponomareva
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
| | - Vadim V. Salnikov
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
| | - Guzalia F. Zakirjanova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
- Department of Normal Physiology, Kazan State Medical University, 49 Butlerova Street, 420012 Kazan, Russia
| | - Alexey M. Petrov
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
- Department of Normal Physiology, Kazan State Medical University, 49 Butlerova Street, 420012 Kazan, Russia
- Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, 420008 Kazan, Russia
| | - Ellya A. Bukharaeva
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of RAS”, 2/31 Lobachevsky Street, P.O. Box 30, 420111 Kazan, Russia; (A.N.T.); (G.V.S.); (Y.G.O.); (V.F.K.); (A.R.T.); (A.A.P.); (V.V.S.); (G.F.Z.)
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Yang XG, Guo HY, Peng Z, Luo HT, Lu S. Application of Electrophysiological Techniques in Assessing of Neuromuscular Junction-Related Disorders. World Neurosurg 2024; 191:165-171. [PMID: 39159673 DOI: 10.1016/j.wneu.2024.08.076] [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: 08/12/2024] [Accepted: 08/13/2024] [Indexed: 08/21/2024]
Abstract
This review aims to comprehensively summarize the application of electrophysiological methods, specifically repetitive nerve stimulation (RNS) and single fiber electromyography (SFEMG), in the diagnosis of neuromuscular junction (NMJ) disorders, including myasthenia gravis, Lambert-Eaton syndrome, and sarcopenia in the elderly. Both RNS and SFEMG have demonstrated high sensitivity and specificity in detecting NMJ abnormalities. RNS aids in distinguishing presynaptic from postsynaptic lesions, while SFEMG provides direct evidence of NMJ function by assessing single motor unit action potentials. Key parameters in SFEMG, such as fiber density, jitter, and pulse blocking, are crucial for evaluating NMJ function. Increased fiber density and jitter value, along with pulse blocking, are often observed in patients with NMJ disorders. However, despite the extensive application of these techniques in various NMJ-related diseases, their role in aging, particularly in sarcopenic patients, remains underexplored, highlighting the need for future research.
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Affiliation(s)
- Xiong-Gang Yang
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China
| | - Hong-Yang Guo
- Department of Rehabilitation, Affiliated Hospital of Hebei University of Technology, Handan, China
| | - Zhi Peng
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China
| | - Hao-Tian Luo
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China
| | - Sheng Lu
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China.
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3
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Liu Y, Lin W. Morphological and functional alterations of neuromuscular synapses in a mouse model of ACTA1 congenital myopathy. Hum Mol Genet 2024; 33:233-244. [PMID: 37883471 PMCID: PMC10800017 DOI: 10.1093/hmg/ddad183] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 10/09/2023] [Accepted: 10/20/2023] [Indexed: 10/28/2023] Open
Abstract
Mutations in skeletal muscle α-actin (Acta1) cause myopathies. In a mouse model of congenital myopathy, heterozygous Acta1 (H40Y) knock-in (Acta1+/Ki) mice exhibit features of human nemaline myopathy, including premature lethality, severe muscle weakness, reduced mobility, and the presence of nemaline rods in muscle fibers. In this study, we investigated the impact of Acta1 (H40Y) mutation on the neuromuscular junction (NMJ). We found that the NMJs were markedly fragmented in Acta1+/Ki mice. Electrophysiological analysis revealed a decrease in amplitude but increase in frequency of miniature end-plate potential (mEPP) at the NMJs in Acta1+/Ki mice, compared with those in wild type (Acta1+/+) mice. Evoked end-plate potential (EPP) remained similar at the NMJs in Acta1+/Ki and Acta1+/+ mice, but quantal content was increased at the NMJs in Acta1+/Ki, compared with Acta1+/+ mice, suggesting a homeostatic compensation at the NMJs in Acta1+/Ki mice to maintain normal levels of neurotransmitter release. Furthermore, short-term synaptic plasticity of the NMJs was compromised in Acta1+/Ki mice. Together, these results demonstrate that skeletal Acta1 H40Y mutation, albeit muscle-origin, leads to both morphological and functional defects at the NMJ.
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Affiliation(s)
- Yun Liu
- Department of Neuroscience, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390-9111, United States
| | - Weichun Lin
- Department of Neuroscience, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390-9111, United States
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Kouyoumdjian JA, Estephan EDP. Electrophysiological evaluation of the neuromuscular junction: a brief review. ARQUIVOS DE NEURO-PSIQUIATRIA 2023; 81:1040-1052. [PMID: 38157872 PMCID: PMC10756823 DOI: 10.1055/s-0043-1777749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024]
Abstract
The nerve terminal and muscle membrane compose the neuromuscular junction. After opening the voltage-gated calcium channels, action potentials from the motor axons provoke a cascade for the acetylcholine release from synaptic vesicles to the synaptic cleft, where it binds to its receptor at the muscle membrane for depolarization. Low amplitude compound muscle action potential typically presents in presynaptic disorders, increasing by more than 100% after a 10-second effort in the Lambert-Eaton myasthenic syndrome and less in botulism. Needle electromyography may show myopathic motor unit action potentials and morphological instability ("jiggle") due to impulse blocking. Low-frequency repetitive nerve stimulation (RNS) is helpful in postsynaptic disorders, such as myasthenia gravis and most congenital myasthenic syndromes, where the number of functioning acetylcholine receptors is reduced. Low-frequency RNS with a decrement >10% is abnormal when comparing the 4th to the first compound muscle action potential amplitude. High-frequency RNS is helpful in presynaptic disorders like Lambert-Eaton myasthenic syndrome, botulism, and some rare congenital myasthenic syndromes. The high-frequency RNS releases more calcium, increasing the acetylcholine with a compound muscle action potential increment. Concentric needle records apparent single-fiber action potentials (spikes). A voluntary activation measures the jitter between spikes from two endplates. An electrical activation measures the jitter of one spike (one endplate). The jitter is the most sensitive test for detecting a neuromuscular junction dysfunction. Most neuromuscular junction disorders are responsive to treatment.
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Affiliation(s)
- João Aris Kouyoumdjian
- Faculdade de Medicina de São José do Rio Preto, Departamento de Ciências Neurológicas, Psiquiatria e Psicologia Médica, São José do Rio Preto SP, Brazil.
| | - Eduardo de Paula Estephan
- Faculdade de Medicina de São José do Rio Preto, Departamento de Ciências Neurológicas, Psiquiatria e Psicologia Médica, São José do Rio Preto SP, Brazil.
- Universidade de São Paulo, Departamento de Neurologia, São Paulo SP, Brazil.
- Faculdade de Medicina Santa Marcelina, São Paulo SP, Brazil.
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Leite APS, Pinto CG, Tibúrcio FC, Muller KS, Padovani CR, Barraviera B, Junior RSF, Leal CV, Matsumura CY, Matheus SMM. Acetylcholine receptors of the neuromuscular junctions present normal distribution after peripheral nerve injury and repair through nerve guidance associated with fibrin biopolymer. Injury 2023; 54:345-361. [PMID: 36446670 DOI: 10.1016/j.injury.2022.11.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 10/26/2022] [Accepted: 11/20/2022] [Indexed: 11/25/2022]
Abstract
Peripheral nerve injuries (PNI) lead to alterations in the Agrin-LRP4-MuSK pathway. This results in disaggregation of AChRs and change from epsilon (mature, innervated) to gamma (immature, denervated) subunit. Tubulization technique has been shown to be effective for PNI repair and it also allows the use of adjuvants, such as fibrin biopolymer (FB). This study evaluated the effect of the association of tubulization with FB after PNI on AChRs and associated proteins. Fifty-two adults male Wistar rats were used, distributed in 4 experimental groups: Sham Control (S), Denervated Control (D); Tubulization (TB) and Tubulization + Fibrin Biopolymer (TB+FB). Catwalk was performed every 15 days. Ninety days after surgery the right soleus muscles and ischiatic nerves were submitted to the following analyses: (a) morphological and morphometric analysis of AChRs by confocal microscopy; (b) morphological and morphometric analysis of the ischiatic nerve; (c) protein quantification of AChRs: alpha, gama, and epsilon, of Schwann cells, agrin, LRP4, MuSK, rapsyn, MMP3, MyoD, myogenin, MURF1 and atrogin-1. The main results were about the NMJs that in the TB+FB group presented morphological and morphometric approximation (compactness index; area of the AChRs and motor plate) to the S group. In addition, there were also an increase of S100 and AChRε protein expression and a decrease of MyoD. These positive association resulted in AChRs stabilization that potentiate the neuromuscular regeneration, which strengthens the use of TB for severe injuries repair and the beneficial effect of FB, along with tubulization technique.
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Affiliation(s)
- Ana Paula Silveira Leite
- Medical School, São Paulo State University (Unesp), Botucatu, SP, Brazil; Division of Anatomy, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil.
| | - Carina Guidi Pinto
- Medical School, São Paulo State University (Unesp), Botucatu, SP, Brazil; Division of Anatomy, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Felipe Cantore Tibúrcio
- Medical School, São Paulo State University (Unesp), Botucatu, SP, Brazil; Division of Anatomy, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Kevin Silva Muller
- Medical School, São Paulo State University (Unesp), Botucatu, SP, Brazil; Division of Anatomy, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Carlos Roberto Padovani
- Division of Biostatistics, Department of Biostatistics, Vegetal Biology, Parasitology and Zoology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Benedito Barraviera
- Medical School, São Paulo State University (Unesp), Botucatu, SP, Brazil; Center for the Study of Venoms and Venomous Animals (Cevap), São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Rui Seabra Ferreira Junior
- Center for the Study of Venoms and Venomous Animals (Cevap), São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Claudenete Vieira Leal
- School of Mechanical Engineering, University of Campinas (Unicamp), Campinas, SP, Brazil
| | - Cintia Yuri Matsumura
- Division of Anatomy, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil
| | - Selma Maria Michelin Matheus
- Division of Anatomy, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, SP, Brazil
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Brooks SV, Guzman SD, Ruiz LP. Skeletal muscle structure, physiology, and function. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:3-16. [PMID: 37562874 DOI: 10.1016/b978-0-323-98818-6.00013-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Contractions of skeletal muscles provide the stability and power for all body movements. Consequently, any impairment in skeletal muscle function results in some degree of instability or immobility. Factors that influence skeletal muscle structure and function are therefore of great interest scientifically and clinically. Injury, neuromuscular disease, and old age are among the factors that commonly contribute to impairments in skeletal muscle function. The goal of this chapter is to summarize the fundamentals of skeletal muscle structure and function to provide foundational knowledge for this Handbook volume. We examine the molecular interactions that provide the basis for the generation of force and movement, discuss mechanisms of the regulation of contraction at the level of myofibers, and introduce concepts of the activation and control of muscle function in vivo. Where appropriate, the chapter updates the emerging science that will increase understanding of muscle function.
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Affiliation(s)
- Susan V Brooks
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.
| | - Steve D Guzman
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Lloyd P Ruiz
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
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Davis LA, Fogarty MJ, Brown A, Sieck GC. Structure and Function of the Mammalian Neuromuscular Junction. Compr Physiol 2022; 12:3731-3766. [PMID: 35950651 PMCID: PMC10461538 DOI: 10.1002/cphy.c210022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The mammalian neuromuscular junction (NMJ) comprises a presynaptic terminal, a postsynaptic receptor region on the muscle fiber (endplate), and the perisynaptic (terminal) Schwann cell. As with any synapse, the purpose of the NMJ is to transmit signals from the nervous system to muscle fibers. This neural control of muscle fibers is organized as motor units, which display distinct structural and functional phenotypes including differences in pre- and postsynaptic elements of NMJs. Motor units vary considerably in the frequency of their activation (both motor neuron discharge rate and duration/duty cycle), force generation, and susceptibility to fatigue. For earlier and more frequently recruited motor units, the structure and function of the activated NMJs must have high fidelity to ensure consistent activation and continued contractile response to sustain vital motor behaviors (e.g., breathing and postural balance). Similarly, for higher force less frequent behaviors (e.g., coughing and jumping), the structure and function of recruited NMJs must ensure short-term reliable activation but not activation sustained for a prolonged period in which fatigue may occur. The NMJ is highly plastic, changing structurally and functionally throughout the life span from embryonic development to old age. The NMJ also changes under pathological conditions including acute and chronic disease. Such neuroplasticity often varies across motor unit types. © 2022 American Physiological Society. Compr Physiol 12:1-36, 2022.
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Affiliation(s)
- Leah A. Davis
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Matthew J. Fogarty
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Alyssa Brown
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Gary C. Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
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Morris CE, Wheeler JJ, Joos B. The Donnan-dominated resting state of skeletal muscle fibers contributes to resilience and longevity in dystrophic fibers. J Gen Physiol 2022; 154:212743. [PMID: 34731883 PMCID: PMC8570295 DOI: 10.1085/jgp.202112914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 09/30/2021] [Indexed: 11/28/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked dystrophin-minus muscle-wasting disease. Ion homeostasis in skeletal muscle fibers underperforms as DMD progresses. But though DMD renders these excitable cells intolerant of exertion, sodium overloaded, depolarized, and spontaneously contractile, they can survive for several decades. We show computationally that underpinning this longevity is a strikingly frugal, robust Pump-Leak/Donnan (P-L/D) ion homeostatic process. Unlike neurons, which operate with a costly “Pump-Leak–dominated” ion homeostatic steady state, skeletal muscle fibers operate with a low-cost “Donnan-dominated” ion homeostatic steady state that combines a large chloride permeability with an exceptionally small sodium permeability. Simultaneously, this combination keeps fiber excitability low and minimizes pump expenditures. As mechanically active, long-lived multinucleate cells, skeletal muscle fibers have evolved to handle overexertion, sarcolemmal tears, ischemic bouts, etc.; the frugality of their Donnan dominated steady state lets them maintain the outsized pump reserves that make them resilient during these inevitable transient emergencies. Here, P-L/D model variants challenged with DMD-type insult/injury (low pump-strength, overstimulation, leaky Nav and cation channels) show how chronic “nonosmotic” sodium overload (observed in DMD patients) develops. Profoundly severe DMD ion homeostatic insult/injury causes spontaneous firing (and, consequently, unwanted excitation–contraction coupling) that elicits cytotoxic swelling. Therefore, boosting operational pump-strength and/or diminishing sodium and cation channel leaks should help extend DMD fiber longevity.
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Affiliation(s)
- Catherine E Morris
- Neuroscience, Ottawa Hospital Research Institute, Ottawa, Canada.,Center for Neural Dynamics, University of Ottawa, Ottawa, Canada
| | | | - Béla Joos
- Center for Neural Dynamics, University of Ottawa, Ottawa, Canada.,Department of Physics, University of Ottawa, Ottawa, Canada
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9
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Howard JF, Bril V, Vu T, Karam C, Peric S, Margania T, Murai H, Bilinska M, Shakarishvili R, Smilowski M, Guglietta A, Ulrichts P, Vangeneugden T, Utsugisawa K, Verschuuren J, Mantegazza R. Safety, efficacy, and tolerability of efgartigimod in patients with generalised myasthenia gravis (ADAPT): a multicentre, randomised, placebo-controlled, phase 3 trial. Lancet Neurol 2021; 20:526-536. [PMID: 34146511 DOI: 10.1016/s1474-4422(21)00159-9] [Citation(s) in RCA: 200] [Impact Index Per Article: 66.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/23/2021] [Accepted: 05/10/2021] [Indexed: 11/15/2022]
Abstract
BACKGROUND There is an unmet need for treatment options for generalised myasthenia gravis that are effective, targeted, well tolerated, and can be used in a broad population of patients. We aimed to assess the safety and efficacy of efgartigimod (ARGX-113), a human IgG1 antibody Fc fragment engineered to reduce pathogenic IgG autoantibody levels, in patients with generalised myasthenia gravis. METHODS ADAPT was a randomised, double-blind, placebo-controlled, phase 3 trial done at 56 neuromuscular academic and community centres in 15 countries in North America, Europe, and Japan. Patients aged at least 18 years with generalised myasthenia gravis were eligible to participate in the study, regardless of anti-acetylcholine receptor antibody status, if they had a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of at least 5 (>50% non-ocular), and were on a stable dose of at least one treatment for generalised myasthenia gravis. Patients were randomly assigned by interactive response technology (1:1) to efgartigimod (10 mg/kg) or matching placebo, administered as four infusions per cycle (one infusion per week), repeated as needed depending on clinical response no sooner than 8 weeks after initiation of the previous cycle. Patients, investigators, and clinical site staff were all masked to treatment allocation. The primary endpoint was proportion of acetylcholine receptor antibody-positive patients who were MG-ADL responders (≥2-point MG-ADL improvement sustained for ≥4 weeks) in the first treatment cycle. The primary analysis was done in the modified intention-to-treat population of all acetylcholine receptor antibody-positive patients who had a valid baseline MG-ADL assessment and at least one post-baseline MG-ADL assessment. The safety analysis included all randomly assigned patients who received at least one dose or part dose of efgartigimod or placebo. This trial is registered at ClinicalTrials.gov (NCT03669588); an open-label extension is ongoing (ADAPT+, NCT03770403). FINDINGS Between Sept 5, 2018, and Nov 26, 2019, 167 patients (84 in the efgartigimod group and 83 in the placebo group) were enrolled, randomly assigned, and treated. 129 (77%) were acetylcholine receptor antibody-positive. Of these patients, more of those in the efgartigimod group were MG-ADL responders (44 [68%] of 65) in cycle 1 than in the placebo group (19 [30%] of 64), with an odds ratio of 4·95 (95% CI 2·21-11·53, p<0·0001). 65 (77%) of 84 patients in the efgartigimod group and 70 (84%) of 83 in the placebo group had treatment-emergent adverse events, with the most frequent being headache (efgartigimod 24 [29%] vs placebo 23 [28%]) and nasopharyngitis (efgartigimod ten [12%] vs placebo 15 [18%]). Four (5%) efgartigimod-treated patients and seven (8%) patients in the placebo group had a serious adverse event. Three patients in each treatment group (4%) discontinued treatment during the study. There were no deaths. INTERPRETATION Efgartigimod was well tolerated and efficacious in patients with generalised myasthenia gravis. The individualised dosing based on clinical response was a unique feature of ADAPT, and translation to clinical practice with longer term safety and efficacy data will be further informed by the ongoing open-label extension. FUNDING argenx.
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Affiliation(s)
- James F Howard
- Department of Neurology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Vera Bril
- Ellen & Martin Prosserman Centre for Neuromuscular Diseases, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Tuan Vu
- Department of Neurology, University of South Florida Morsani College of Medicine, Tampa, FL, USA
| | - Chafic Karam
- Penn Neuroscience Center-Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Stojan Peric
- Neurology Clinic, Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Temur Margania
- Department of Neurology and Neurorehabilitation, New Hospitals, Tbilisi, Georgia
| | - Hiroyuki Murai
- Department of Neurology, School of Medicine, International University of Health and Welfare, Narita, Japan
| | - Malgorzata Bilinska
- Department and Clinic of Neurology, Wroclaw Medical University, Wroclaw, Poland
| | | | - Marek Smilowski
- Department of Hematology and Bone Marrow Transplantation, Medical University of Silesia, Katowice, Poland
| | | | | | | | | | - Jan Verschuuren
- Department of Neurology, Leiden University Medical Center, Leiden, Netherlands
| | - Renato Mantegazza
- Department of Neuroimmunology and Neuromuscular Diseases, Fondazione Istituto Neurologico Carlo Besta, Milan, Italy
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10
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Hostrup M, Cairns SP, Bangsbo J. Muscle Ionic Shifts During Exercise: Implications for Fatigue and Exercise Performance. Compr Physiol 2021; 11:1895-1959. [PMID: 34190344 DOI: 10.1002/cphy.c190024] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exercise causes major shifts in multiple ions (e.g., K+ , Na+ , H+ , lactate- , Ca2+ , and Cl- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K+ , Na+ , and Ca2+ during fatiguing exercise, while changes in gradients for Cl- and Cl- conductance may exert either protective or detrimental effects on fatigue. Myocellular H+ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca2+ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na+ /K+ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K+ and Cl- , respectively via metabolic regulation of the ATP-sensitive K+ channel (KATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.
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Affiliation(s)
- Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Simeon Peter Cairns
- SPRINZ, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand.,Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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11
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Vornanen M. Feeling the heat: source–sink mismatch as a mechanism underlying the failure of thermal tolerance. J Exp Biol 2020; 223:223/16/jeb225680. [DOI: 10.1242/jeb.225680] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
ABSTRACT
A mechanistic explanation for the tolerance limits of animals at high temperatures is still missing, but one potential target for thermal failure is the electrical signaling off cells and tissues. With this in mind, here I review the effects of high temperature on the electrical excitability of heart, muscle and nerves, and refine a hypothesis regarding high temperature-induced failure of electrical excitation and signal transfer [the temperature-dependent deterioration of electrical excitability (TDEE) hypothesis]. A central tenet of the hypothesis is temperature-dependent mismatch between the depolarizing ion current (i.e. source) of the signaling cell and the repolarizing ion current (i.e. sink) of the receiving cell, which prevents the generation of action potentials (APs) in the latter. A source–sink mismatch can develop in heart, muscles and nerves at high temperatures owing to opposite effects of temperature on source and sink currents. AP propagation is more likely to fail at the sites of structural discontinuities, including electrically coupled cells, synapses and branching points of nerves and muscle, which impose an increased demand of inward current. At these sites, temperature-induced source–sink mismatch can reduce AP frequency, resulting in low-pass filtering or a complete block of signal transmission. In principle, this hypothesis can explain a number of heat-induced effects, including reduced heart rate, reduced synaptic transmission between neurons and reduced impulse transfer from neurons to muscles. The hypothesis is equally valid for ectothermic and endothermic animals, and for both aquatic and terrestrial species. Importantly, the hypothesis is strictly mechanistic and lends itself to experimental falsification.
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Affiliation(s)
- Matti Vornanen
- Department of Environmental and Biological Sciences , University of Eastern Finland, 80101 Joensuu, Finland
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12
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Abstract
This article discusses antibodies associated with immune-mediated myasthenia gravis and the pathologic action of these antibodies at the neuromuscular junctions of skeletal muscle. To explain how these antibodies act, we consider the physiology of neuromuscular transmission with emphasis on 4 features: the structure of the neuromuscular junction; the roles of postsynaptic acetylcholine receptors and voltage-gated Na+ channels and in converting the chemical signal from the nerve terminal into a propagated action potential on the muscle fiber that triggers muscle contraction; the safety factor for neuromuscular transmission; and how the safety factor is reduced in different forms of autoimmune myasthenia gravis.
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Affiliation(s)
- Robert L Ruff
- Department of Neurology, Case Western University School of Medicine, The Metro Health System, 2500 Metro Health Drive, Cleveland, OH 44109, USA; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Robert P Lisak
- Department of Neurology, Wayne State University School of Medicine, 8D University Health Center, 4201 St Antoine, Detroit, MI 48201, USA; Department of Biochemistry, Microbiology and Immunology, Wayne State University, Detroit, MI, USA.
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13
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Bernareggi A, Sciancalepore M, Lorenzon P. Interplay Between Cholinergic and Adenosinergic Systems in Skeletal Muscle. Neuroscience 2019; 439:41-47. [PMID: 31121259 DOI: 10.1016/j.neuroscience.2019.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 02/06/2023]
Abstract
Since the pioneering works of Ricardo Miledi, the neuromuscular junction represents the best example of a synapse where ACh is the neurotransmitter acting on nicotinic ACh receptors. ATP, co-released with ACh, is promptly degraded to Ado, which acts as a modulator of the cholinergic synaptic activity. Consequently, both ACh and adenosine play a crucial role in controlling the nerve-muscle communication. Apart from their role in the context of synaptic transmission, ACh and adenosine are autocrinally released by skeletal muscle cells, suggesting also a non nerve-driven function of these molecules. Indeed, the existence of cholinergic and adenosinergic systems has been widely described in many other non neuronal cell types. In this review, we will describe the two systems and their interplay in non-innervated differentiating skeletal muscle cells, and in innervated adult skeletal muscle fibers. We believe that the better comprehension of the interactions between the activity of nAChRs and adenosine could help the knowledge of skeletal muscle physiology. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Annalisa Bernareggi
- Department of Life Sciences, University of Trieste, Trieste, Italy; B.R.A.I.N., Centre for Neuroscience, Trieste, Italy.
| | - Marina Sciancalepore
- Department of Life Sciences, University of Trieste, Trieste, Italy; B.R.A.I.N., Centre for Neuroscience, Trieste, Italy
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, Trieste, Italy; B.R.A.I.N., Centre for Neuroscience, Trieste, Italy
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14
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Cholesterol and the Safety Factor for Neuromuscular Transmission. Int J Mol Sci 2019; 20:ijms20051046. [PMID: 30823359 PMCID: PMC6429197 DOI: 10.3390/ijms20051046] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/23/2019] [Accepted: 02/24/2019] [Indexed: 12/12/2022] Open
Abstract
A present review is devoted to the analysis of literature data and results of own research. Skeletal muscle neuromuscular junction is specialized to trigger the striated muscle fiber contraction in response to motor neuron activity. The safety factor at the neuromuscular junction strongly depends on a variety of pre- and postsynaptic factors. The review focuses on the crucial role of membrane cholesterol to maintain a high efficiency of neuromuscular transmission. Cholesterol metabolism in the neuromuscular junction, its role in the synaptic vesicle cycle and neurotransmitter release, endplate electrogenesis, as well as contribution of cholesterol to the synaptogenesis, synaptic integrity, and motor disorders are discussed.
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15
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Kravtsova VV, Timonina NA, Zakir’yanova GF, Sokolova AV, Mikhailov VM, Zefirov AL, Krivoi II. The Structural and Functional Characteristics of the Motor End Plates of Dysferlin-Deficient Mice. NEUROCHEM J+ 2018. [DOI: 10.1134/s1819712418040049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Vilchinskaya NA, Krivoi II, Shenkman BS. AMP-Activated Protein Kinase as a Key Trigger for the Disuse-Induced Skeletal Muscle Remodeling. Int J Mol Sci 2018; 19:ijms19113558. [PMID: 30424476 PMCID: PMC6274864 DOI: 10.3390/ijms19113558] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/02/2018] [Accepted: 11/09/2018] [Indexed: 12/25/2022] Open
Abstract
Molecular mechanisms that trigger disuse-induced postural muscle atrophy as well as myosin phenotype transformations are poorly studied. This review will summarize the impact of 5′ adenosine monophosphate -activated protein kinase (AMPK) activity on mammalian target of rapamycin complex 1 (mTORC1)-signaling, nuclear-cytoplasmic traffic of class IIa histone deacetylases (HDAC), and myosin heavy chain gene expression in mammalian postural muscles (mainly, soleus muscle) under disuse conditions, i.e., withdrawal of weight-bearing from ankle extensors. Based on the current literature and the authors’ own experimental data, the present review points out that AMPK plays a key role in the regulation of signaling pathways that determine metabolic, structural, and functional alternations in skeletal muscle fibers under disuse.
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Affiliation(s)
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia.
| | - Boris S Shenkman
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow 123007, Russia.
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17
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Petrov KA, Nikolsky EE, Masson P. Autoregulation of Acetylcholine Release and Micro-Pharmacodynamic Mechanisms at Neuromuscular Junction: Selective Acetylcholinesterase Inhibitors for Therapy of Myasthenic Syndromes. Front Pharmacol 2018; 9:766. [PMID: 30050445 PMCID: PMC6052098 DOI: 10.3389/fphar.2018.00766] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/25/2018] [Indexed: 12/22/2022] Open
Abstract
Neuromuscular junctions (NMJs) are directly involved into such indispensable to life processes as respiration and locomotion. However, motor nerve forms only one synaptic contact at each muscle fiber. This unique configuration requires specific properties and constrains to be effective. The very high density of acetylcholine receptors (AChRs) of muscle type in synaptic cleft and an excess of acetylcholine (ACh) released under physiological conditions make this synapse extremely reliable. Nevertheless, under pathological conditions such as myasthenia gravis and congenital myasthenic syndromes, the safety factor can be markedly reduced. Drugs used for short-term symptomatic therapy of these pathological states, cause partial inhibition of cholinesterases (ChEs). These enzymes catalyze the hydrolysis of ACh, thus terminate its action on AChRs. Extension of the lifetime of ACh molecules compensates muscular AChRs abnormalities and, consequently, rescues muscle contractions. In this mini review, we will first outline the functional organization of the NMJ, and then, consider the concept of the safety factor and how it may be changed. This will be followed by a look at autoregulation of ACh release that influences the safety factor of NMJs. Finally, we will consider the morphological features of NMJs as a putative reserve to increase effectiveness of pathological muscle weakness therapy by ChEs inhibitors due to opportunity to use micro-pharmacodynamic mechanisms.
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Affiliation(s)
- Konstantin A Petrov
- A.E. Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan, Russia.,Neuropharmacology Lab, Kazan Federal University, Kazan, Russia
| | - Evgeny E Nikolsky
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan, Russia
| | - Patrick Masson
- Neuropharmacology Lab, Kazan Federal University, Kazan, Russia
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18
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Chibalin AV, Benziane B, Zakyrjanova GF, Kravtsova VV, Krivoi II. Early endplate remodeling and skeletal muscle signaling events following rat hindlimb suspension. J Cell Physiol 2018; 233:6329-6336. [PMID: 29719042 DOI: 10.1002/jcp.26594] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 03/12/2018] [Indexed: 12/30/2022]
Abstract
Motor endplates naturally undergo continual morphological changes that are altered in response to changes in neuromuscular activity. This study examines the consequences of acute (6-12 hr) disuse following hindlimb suspension on rat soleus muscle endplate structural stability. We identify early changes in several key signaling events including markers of protein kinase activation, AMPK phosphorylation and autophagy markers which may play a role in endplate remodeling. Acute disuse does not change endplate fragmentation, however, it decreases both the individual fragments and the total endplate area. This decrease was accompanied by an increase in the mean fluorescence intensity from the nicotinic acetylcholine receptors which compensate the endplate area loss. Muscle disuse decreased phosphorylation of AMPK and its substrate ACC, and stimulated mTOR controlled protein synthesis pathway and stimulated autophagy. Our findings provide evidence that changes in endplate stability are accompanied by reduced AMPK phosphorylation and an increase in autophagy markers, and these changes are evident within hours of onset of skeletal muscle disuse.
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Affiliation(s)
- Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Boubacar Benziane
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Guzalija F Zakyrjanova
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia.,Department of Normal Physiology, Kazan State Medical University, Kazan, Russia
| | - Violetta V Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
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19
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20
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van der Pijl EM, van Putten M, Niks EH, Verschuuren JJGM, Aartsma-Rus A, Plomp JJ. Characterization of neuromuscular synapse function abnormalities in multiple Duchenne muscular dystrophy mouse models. Eur J Neurosci 2016; 43:1623-35. [PMID: 27037492 DOI: 10.1111/ejn.13249] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 11/30/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked myopathy caused by dystrophin deficiency. Dystrophin is present intracellularly at the sarcolemma, connecting actin to the dystrophin-associated glycoprotein complex. Interestingly, it is enriched postsynaptically at the neuromuscular junction (NMJ), but its synaptic function is largely unknown. Utrophin, a dystrophin homologue, is also concentrated at the NMJ, and upregulated in DMD. It is possible that the absence of dystrophin at NMJs in DMD causes neuromuscular transmission defects that aggravate muscle weakness. We studied NMJ function in mdx mice (lacking dystrophin) and wild type mice. In addition, mdx/utrn(+/-) and mdx/utrn(-/-) mice (lacking utrophin) were used to investigate influences of utrophin levels. The three Duchenne mouse models showed muscle weakness when comparatively tested in vivo, with mdx/utrn(-/-) mice being weakest. Ex vivo muscle contraction and electrophysiological studies showed a reduced safety factor of neuromuscular transmission in all models. NMJs had ~ 40% smaller miniature endplate potential amplitudes compared with wild type, indicating postsynaptic sensitivity loss for the neurotransmitter acetylcholine. However, nerve stimulation-evoked endplate potential amplitudes were unchanged. Consequently, quantal content (i.e. the number of acetylcholine quanta released per nerve impulse) was considerably increased. Such a homeostatic compensatory increase in neurotransmitter release is also found at NMJs in myasthenia gravis, where autoantibodies reduce acetylcholine receptors. However, high-rate nerve stimulation induced exaggerated endplate potential rundown. Study of NMJ morphology showed that fragmentation of acetylcholine receptor clusters occurred in all models, being most severe in mdx/utrn(-/-) mice. Overall, we showed mild 'myasthenia-like' neuromuscular synaptic dysfunction in several Duchenne mouse models, which possibly affects muscle weakness and degeneration.
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Affiliation(s)
- Elizabeth M van der Pijl
- Department of Neurology, Leiden University Medical Centre, Research Building S5-P, P.O. Box 9600 2300 RC, Leiden, The Netherlands
| | - Maaike van Putten
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Erik H Niks
- Department of Neurology, Leiden University Medical Centre, Research Building S5-P, P.O. Box 9600 2300 RC, Leiden, The Netherlands
| | - Jan J G M Verschuuren
- Department of Neurology, Leiden University Medical Centre, Research Building S5-P, P.O. Box 9600 2300 RC, Leiden, The Netherlands
| | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Jaap J Plomp
- Department of Neurology, Leiden University Medical Centre, Research Building S5-P, P.O. Box 9600 2300 RC, Leiden, The Netherlands
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21
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Silveira PE, Lima RF, Guimarães JDS, Molgó J, Naves LA, Kushmerick C. Ryanodine and inositol triphosphate receptors modulate facilitation and tetanic depression at the frog neuromuscular junction. Muscle Nerve 2015; 52:623-30. [PMID: 25600698 DOI: 10.1002/mus.24571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2015] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Short-term plasticity of synaptic function is an important physiological control of transmitter release. Short-term plasticity can be regulated by intracellular calcium released by ryanodine and inositol triphosphate (IP3) receptors, but the role of these receptors at the neuromuscular junction is understood incompletely. METHODS We measured short-term plasticity of evoked endplate potential (EPP) amplitudes from frog neuromuscular junctions treated with ryanodine, 2-aminoethoxydiphenylborane (2-APB), or 1-[6-[[(17β)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U- 73122). RESULTS Ryanodine decreases paired-pulse facilitation for intervals <20 ms and markedly decreases tetanic depression. Treatment with 2-APB reduces EPP amplitude, increases paired-pulse facilitation for intervals of <20 ms, and significantly reduces tetanic depression. U-73122 decreases EPP amplitude and decreases paired-pulse depression for intervals <20 ms. CONCLUSIONS Ryanodine, IP3 receptors, and phospholipase C modulate short-term plasticity of transmitter release at the neuromuscular junction. These results suggest possible targets for improving the safety factor of neuromuscular transmission during repetitive activity of the neuromuscular junction.
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Affiliation(s)
- Priscila E Silveira
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antonio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Ricardo F Lima
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antonio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil.,Departamento Fisiologia e Farmacologia, UFC, Fortaleza, Brazil
| | - Jennifer D S Guimarães
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antonio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Jordi Molgó
- Institut Fédératif de Neurobiologie Alfred Fessard Laboratoire de Neurobiologie et Dévelopement, CNRS, Gif sur Yvette, France
| | - Ligia A Naves
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antonio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Christopher Kushmerick
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antonio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
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22
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Voigt T, Neve A, Schümperli D. The craniosacral progression of muscle development influences the emergence of neuromuscular junction alterations in a severe murine model for spinal muscular atrophy. Neuropathol Appl Neurobiol 2015; 40:416-34. [PMID: 23718187 DOI: 10.1111/nan.12064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 05/30/2013] [Accepted: 05/21/2013] [Indexed: 11/28/2022]
Abstract
AIMS As 4-day-old mice of the severe spinal muscular atrophy (SMA) model (dying at 5-8 days) display pronounced neuromuscular changes in the diaphragm but not the soleus muscle, we wanted to gain more insight into the relationship between muscle development and the emergence of pathological changes and additionally to analyse intercostal muscles which are affected in human SMA. METHODS Structures of muscle fibres and neuromuscular junctions (NMJs) of the diaphragm, intercostal and calf muscles of prenatal (E21) and postnatal (P0 and P4) healthy and SMA mice were analysed by light and transmission electron microscopy. NMJ innervation was studied by whole mount immunofluorescence in diaphragms of P4 mice. RESULTS During this period, the investigated muscles still show a significant neck-to-tail developmental gradient. The diaphragm and calf muscles are most and least advanced, respectively, with respect to muscle fibre fusion and differentiation. The number and depth of subsynaptic folds increases, and perisynaptic Schwann cells (PSCs) acquire a basal lamina on their outer surface. Subsynaptic folds are connected to an extensive network of tubules and beaded caveolae, reminiscent of the T system in adult muscle. Interestingly, intercostal muscles from P4 SMA mice show weaker pathological involvement (that is, vacuolization of PSCs and perineurial cells) than those previously described by us for the diaphragm, whereas calf muscles show no pathological changes. CONCLUSION SMA-related alterations appear to occur only when the muscles have reached a certain developmental maturity. Moreover, glial cells, in particular PSCs, play an important role in SMA pathogenesis.
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Affiliation(s)
- Tilman Voigt
- Institute of Anatomy, University of Bern, Bern, Switzerland
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23
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Plomp JJ, Morsch M, Phillips WD, Verschuuren JJGM. Electrophysiological analysis of neuromuscular synaptic function in myasthenia gravis patients and animal models. Exp Neurol 2015; 270:41-54. [PMID: 25620417 DOI: 10.1016/j.expneurol.2015.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/07/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Study of the electrophysiological function of the neuromuscular junction (NMJ) is instrumental in the understanding of the symptoms and pathophysiology of myasthenia gravis (MG), an autoimmune disorder characterized by fluctuating and fatigable muscle weakness. Most patients have autoantibodies to the acetylcholine receptor at the NMJ. However, in recent years autoantibodies to other crucial postsynaptic membrane proteins have been found in previously 'seronegative' MG patients. Electromyographical recording of compound and single-fibre muscle action potentials provides a crucial in vivo method to determine neuromuscular transmission failure while ex vivo (miniature) endplate potential recordings can reveal the precise synaptic impairment. Here we will review these electrophysiological methods used to assess NMJ function and discuss their application and typical results found in the diagnostic and experimental study of patients and animal models of the several forms of MG.
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Affiliation(s)
- Jaap J Plomp
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.
| | - Marco Morsch
- Motor Neuron Disease Research Group, Macquarie University, Sydney, Australia
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24
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Isoform-specific Na,K-ATPase alterations precede disuse-induced atrophy of rat soleus muscle. BIOMED RESEARCH INTERNATIONAL 2015; 2015:720172. [PMID: 25654120 PMCID: PMC4309216 DOI: 10.1155/2015/720172] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/18/2014] [Indexed: 11/17/2022]
Abstract
This study examines the isoform-specific effects of short-term hindlimb suspension (HS) on the Na,K-ATPase in rat soleus muscle. Rats were exposed to 24–72 h of HS and we analyzed the consequences on soleus muscle mass and contractile parameters; excitability and the resting membrane potential (RMP) of muscle fibers; the electrogenic activity, protein, and mRNA content of the α1 and α2 Na,K-ATPase; the functional activity and plasma membrane localization of the α2 Na,K-ATPase. Our results indicate that 24–72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers. This decrease occurs prior to muscle atrophy or any change in contractile parameters. The α2 mRNA and protein content increased after 24 h of HS and returned to initial levels at 72 h; however, even the increased content was not able to restore α2 enzyme activity in the disused soleus muscle. There was no change in the membrane localization of α2 Na,K-ATPase. The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change. Our findings suggest that skeletal muscle use is absolutely required for α2 Na,K-ATPase transport activity and provide the first evidence that Na,K-ATPase alterations precede HS-induced muscle atrophy.
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25
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Role of cholesterol in the maintenance of endplate electrogenesis in rat diaphragm. Bull Exp Biol Med 2015; 158:298-300. [PMID: 25573354 DOI: 10.1007/s10517-015-2745-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Indexed: 10/24/2022]
Abstract
Methyl-β-cyclodextrin (0.1 mM) reduced resting potential of muscle fibers and abolished local endplate membrane hyperpolarization in rat diaphragm. This effect was associated with selective reduction of electrogenic activity of α2-isoform of Na,K-ATPase without changes in the level of intracellular acetylcholine. Experiments with cholesterol marker filipin showed that methyl-β-cyclodextrin in this dose induced cholesterol translocation from lipid rafts to liquid phase of the membrane without its release into extracellular space. This modification of lipid rafts by methyl-β-cyclodextrin presumably impaired the mechanism maintaining electrogenesis in endplates mediated by modulation of Na,K-ATPase by non-quantum acetylcholine. Cholesterol can serve as a molecular component of this mechanism.
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26
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Patra K, Lyons DJ, Bauer P, Hilscher MM, Sharma S, Leão RN, Kullander K. A role for solute carrier family 10 member 4, or vesicular aminergic-associated transporter, in structural remodelling and transmitter release at the mouse neuromuscular junction. Eur J Neurosci 2014; 41:316-27. [DOI: 10.1111/ejn.12790] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 10/14/2014] [Accepted: 10/17/2014] [Indexed: 12/27/2022]
Affiliation(s)
| | - David J. Lyons
- Department of Neuroscience; Uppsala University; Uppsala Sweden
| | - Pavol Bauer
- Department of Neuroscience; Uppsala University; Uppsala Sweden
| | - Markus M. Hilscher
- Department of Neuroscience; Uppsala University; Uppsala Sweden
- The Beijer Laboratory for Gene and Neurosciences; Uppsala Sweden
- Brain Institute; Federal University of Rio Grande do Norte; Natal Brazil
| | - Swati Sharma
- Department of Neuroscience; Uppsala University; Uppsala Sweden
| | - Richardson N. Leão
- Department of Neuroscience; Uppsala University; Uppsala Sweden
- The Beijer Laboratory for Gene and Neurosciences; Uppsala Sweden
- Brain Institute; Federal University of Rio Grande do Norte; Natal Brazil
| | - Klas Kullander
- Department of Neuroscience; Uppsala University; Uppsala Sweden
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Bates ME, Buckman JF, Nguyen TT. A role for cognitive rehabilitation in increasing the effectiveness of treatment for alcohol use disorders. Neuropsychol Rev 2013; 23:27-47. [PMID: 23412885 PMCID: PMC3610413 DOI: 10.1007/s11065-013-9228-3] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 01/31/2013] [Indexed: 12/14/2022]
Abstract
Neurocognitive impairments are prevalent in persons seeking treatment for alcohol use disorders (AUDs). These impairments and their physical, social, psychological and occupational consequences vary in severity across persons, much like those resulting from traumatic brain injury; however, due to their slower course of onset, alcohol-related cognitive impairments are often overlooked both within and outside of the treatment setting. Evidence suggests that cognitive impairments can impede treatment goals through their effects on treatment processes. Although some recovery of alcohol-related cognitive impairments often occurs after cessation of drinking (time-dependent recovery), the rate and extent of recovery is variable across cognitive domains and individuals. Following a long hiatus in scientific interest, a new generation of research aims to facilitate treatment process and improve AUD treatment outcomes by directly promoting cognitive recovery (experience-dependent recovery). This review updates knowledge about the nature and course of cognitive and brain impairments associated with AUD, including cognitive effects of adolescent AUD. We summarize current evidence for indirect and moderating relationships of cognitive impairment to treatment outcome, and discuss how advances in conceptual frameworks of brain-behavior relationships are fueling the development of novel AUD interventions that include techniques for cognitive remediation. Emerging evidence suggests that such interventions can be effective in promoting cognitive recovery in persons with AUD and other substance use disorders, and potentially increasing the efficacy of AUD treatments. Finally, translational approaches based on cognitive science, neurophysiology, and neuroscience research are considered as promising future directions for effective treatment development that includes cognitive rehabilitation.
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Affiliation(s)
- Marsha E Bates
- Center of Alcohol Studies, Rutgers, The State University of New Jersey, 607 Allison Road, Piscataway, NJ 08854-8001, USA.
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Belaya K, Finlayson S, Cossins J, Liu WW, Maxwell S, Palace J, Beeson D. Identification of DPAGT1 as a new gene in which mutations cause a congenital myasthenic syndrome. Ann N Y Acad Sci 2012; 1275:29-35. [PMID: 23278575 PMCID: PMC6044425 DOI: 10.1111/j.1749-6632.2012.06790.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited disorders that arise from impaired signal transmission at the neuromuscular synapse. They are characterized by fatigable muscle weakness. This is a heterogenous group of disorders with 15 different genes implicated in the development of the disease. Using whole-exome sequencing we identified DPAGT1 as a new gene associated with CMS. DPAGT1 catalyses the first step of N-linked protein glycosylation. DPAGT1 patients are characterized by weakness of limb muscles, response to treatment with cholinesterase inhibitors, and the presence of tubular aggregates on muscle biopsy. We showed that DPAGT1 is required for glycosylation of acetylcholine receptor (AChR) subunits and efficient export of AChR to the cell surface. We suggest that the primary pathogenic mechanism of DPAGT1-associated CMS is reduced levels of AChRs at the endplate region. This finding demonstrates that impairment of the N-linked glycosylation pathway can lead to the development of CMS.
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Affiliation(s)
- Katsiaryna Belaya
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom.
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29
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Belaya K, Finlayson S, Slater C, Cossins J, Liu W, Maxwell S, McGowan S, Maslau S, Twigg S, Walls T, Pascual Pascual S, Palace J, Beeson D. Mutations in DPAGT1 cause a limb-girdle congenital myasthenic syndrome with tubular aggregates. Am J Hum Genet 2012; 91:193-201. [PMID: 22742743 PMCID: PMC3397259 DOI: 10.1016/j.ajhg.2012.05.022] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/18/2012] [Accepted: 05/29/2012] [Indexed: 11/28/2022] Open
Abstract
Congenital myasthenic syndromes are a heterogeneous group of inherited disorders that arise from impaired signal transmission at the neuromuscular synapse. They are characterized by fatigable muscle weakness. We performed whole-exome sequencing to determine the underlying defect in a group of individuals with an inherited limb-girdle pattern of myasthenic weakness. We identify DPAGT1 as a gene in which mutations cause a congenital myasthenic syndrome. We describe seven different mutations found in five individuals with DPAGT1 mutations. The affected individuals share a number of common clinical features, including involvement of proximal limb muscles, response to treatment with cholinesterase inhibitors and 3,4-diaminopyridine, and the presence of tubular aggregates in muscle biopsies. Analyses of motor endplates from two of the individuals demonstrate a severe reduction of endplate acetylcholine receptors. DPAGT1 is an essential enzyme catalyzing the first committed step of N-linked protein glycosylation. Our findings underscore the importance of N-linked protein glycosylation for proper functioning of the neuromuscular junction. Using the DPAGT1-specific inhibitor tunicamycin, we show that DPAGT1 is required for efficient glycosylation of acetylcholine-receptor subunits and for efficient export of acetylcholine receptors to the cell surface. We suggest that the primary pathogenic mechanism of DPAGT1 mutations is reduced levels of acetylcholine receptors at the endplate region. These individuals share clinical features similar to those of congenital myasthenic syndrome due to GFPT1 mutations, and their disorder might be part of a larger subgroup comprising the congenital myasthenic syndromes that result from defects in the N-linked glycosylation pathway and that manifest through impaired neuromuscular transmission.
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Affiliation(s)
- Katsiaryna Belaya
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Sarah Finlayson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Clarke R. Slater
- Institute of Neuroscience, Newcastle Biomedicine, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Wei Wei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Susan Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Simon J. McGowan
- Computational Biology Research Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Siarhei Maslau
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Stephen R.F. Twigg
- Clinical Genetics, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Timothy J. Walls
- Department of Neurology, Regional Neurosciences Centre, Newcastle General Hospital, Newcastle upon Tyne NE1 4LP, UK
| | - Samuel I. Pascual Pascual
- Servicio de Neurologia Pediátrica. Hospital Universitario La Paz, Departamento de Pediatria, Universidad Autónoma de Madrid, Madrid 28046, Spain
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
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Chibalin AV, Heiny JA, Benziane B, Prokofiev AV, Vasiliev AV, Kravtsova VV, Krivoi II. Chronic nicotine modifies skeletal muscle Na,K-ATPase activity through its interaction with the nicotinic acetylcholine receptor and phospholemman. PLoS One 2012; 7:e33719. [PMID: 22442718 PMCID: PMC3307752 DOI: 10.1371/journal.pone.0033719] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 02/15/2012] [Indexed: 11/23/2022] Open
Abstract
Our previous finding that the muscle nicotinic acetylcholine receptor (nAChR) and the Na,K-ATPase interact as a regulatory complex to modulate Na,K-ATPase activity suggested that chronic, circulating nicotine may alter this interaction, with long-term changes in the membrane potential. To test this hypothesis, we chronically exposed rats to nicotine delivered orally for 21–31 days. Chronic nicotine produced a steady membrane depolarization of ∼3 mV in the diaphragm muscle, which resulted from a net change in electrogenic transport by the Na,K-ATPase α2 and α1 isoforms. Electrogenic transport by the α2 isoform increased (+1.8 mV) while the activity of the α1 isoform decreased (−4.4 mV). Protein expression of Na,K-ATPase α1 or α2 isoforms and the nAChR did not change; however, the content of α2 subunit in the plasma membrane decreased by 25%, indicating that its stimulated electrogenic transport is due to an increase in specific activity. The physical association between the nAChR, the Na,K-ATPase α1 or α2 subunits, and the regulatory subunit of the Na,K-ATPase, phospholemman (PLM), measured by co-immuno precipitation, was stable and unchanged. Chronic nicotine treatment activated PKCα/β2 and PKCδ and was accompanied by parallel increases in PLM phosphorylation at Ser63 and Ser68. Collectively, these results demonstrate that nicotine at chronic doses, acting through the nAChR-Na,K-ATPase complex, is able to modulate Na,K-ATPase activity in an isoform-specific manner and that the regulatory range includes both stimulation and inhibition of enzyme activity. Cholinergic modulation of Na,K-ATPase activity is achieved, in part, through activation of PKC and phosphorylation of PLM.
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Affiliation(s)
- Alexander V. Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
- * E-mail: (AC); (IIK)
| | - Judith A. Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Boubacar Benziane
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Alexander V. Prokofiev
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | - Alexander V. Vasiliev
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | - Violetta V. Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | - Igor I. Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
- * E-mail: (AC); (IIK)
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