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Kedlian VR, Wang Y, Liu T, Chen X, Bolt L, Tudor C, Shen Z, Fasouli ES, Prigmore E, Kleshchevnikov V, Pett JP, Li T, Lawrence JEG, Perera S, Prete M, Huang N, Guo Q, Zeng X, Yang L, Polański K, Chipampe NJ, Dabrowska M, Li X, Bayraktar OA, Patel M, Kumasaka N, Mahbubani KT, Xiang AP, Meyer KB, Saeb-Parsy K, Teichmann SA, Zhang H. Human skeletal muscle aging atlas. NATURE AGING 2024; 4:727-744. [PMID: 38622407 PMCID: PMC11108788 DOI: 10.1038/s43587-024-00613-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 03/19/2024] [Indexed: 04/17/2024]
Abstract
Skeletal muscle aging is a key contributor to age-related frailty and sarcopenia with substantial implications for global health. Here we profiled 90,902 single cells and 92,259 single nuclei from 17 donors to map the aging process in the adult human intercostal muscle, identifying cellular changes in each muscle compartment. We found that distinct subsets of muscle stem cells exhibit decreased ribosome biogenesis genes and increased CCL2 expression, causing different aging phenotypes. Our atlas also highlights an expansion of nuclei associated with the neuromuscular junction, which may reflect re-innervation, and outlines how the loss of fast-twitch myofibers is mitigated through regeneration and upregulation of fast-type markers in slow-twitch myofibers with age. Furthermore, we document the function of aging muscle microenvironment in immune cell attraction. Overall, we present a comprehensive human skeletal muscle aging resource ( https://www.muscleageingcellatlas.org/ ) together with an in-house mouse muscle atlas to study common features of muscle aging across species.
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Affiliation(s)
- Veronika R Kedlian
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Yaning Wang
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Tianliang Liu
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xiaoping Chen
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Liam Bolt
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Catherine Tudor
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Zhuojian Shen
- Department of Thoracic Surgery, Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Eirini S Fasouli
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Elena Prigmore
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | | | - Jan Patrick Pett
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Tong Li
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - John E G Lawrence
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Shani Perera
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Martin Prete
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Ni Huang
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Qin Guo
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xinrui Zeng
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Lu Yang
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Krzysztof Polański
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Nana-Jane Chipampe
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Monika Dabrowska
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Xiaobo Li
- Core Facilities for Medical Science, Sun Yat-sen University, Guangzhou, China
| | - Omer Ali Bayraktar
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Minal Patel
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Natsuhiko Kumasaka
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Krishnaa T Mahbubani
- Department of Surgery, University of Cambridge, Cambridge, UK
- Collaborative Biorepository for Translational Medicine (CBTM), NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Andy Peng Xiang
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Kerstin B Meyer
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Kourosh Saeb-Parsy
- Department of Surgery, University of Cambridge, Cambridge, UK.
- Collaborative Biorepository for Translational Medicine (CBTM), NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
| | - Sarah A Teichmann
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK.
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
| | - Hongbo Zhang
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
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Gessler L, Huraskin D, Jian Y, Eiber N, Hu Z, Prószyński T, Hashemolhosseini S. The YAP1/TAZ-TEAD transcriptional network regulates gene expression at neuromuscular junctions in skeletal muscle fibers. Nucleic Acids Res 2024; 52:600-624. [PMID: 38048326 PMCID: PMC10810223 DOI: 10.1093/nar/gkad1124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/06/2023] [Accepted: 11/09/2023] [Indexed: 12/06/2023] Open
Abstract
We examined YAP1/TAZ-TEAD signaling pathway activity at neuromuscular junctions (NMJs) of skeletal muscle fibers in adult mice. Our investigations revealed that muscle-specific knockouts of Yap1 or Taz, or both, demonstrate that these transcriptional coactivators regulate synaptic gene expression, the number and morphology of NMJs, and synaptic nuclei. Yap1 or Taz single knockout mice display reduced grip strength, fragmentation of NMJs, and accumulation of synaptic nuclei. Yap1/Taz muscle-specific double knockout mice do not survive beyond birth and possess almost no NMJs, the few detectable show severely impaired morphology and are organized in widened endplate bands; and with motor nerve endings being mostly absent. Myogenic gene expression is significantly impaired in the denervated muscles of knockout mice. We found that Tead1 and Tead4 transcription rates were increased upon incubation of control primary myotubes with AGRN-conditioned medium. Reduced AGRN-dependent acetylcholine receptor clustering and synaptic gene transcription were observed in differentiated primary Tead1 and Tead4 knockout myotubes. In silico analysis of previously reported genomic occupancy sites of TEAD1/4 revealed evolutionary conserved regions of potential TEAD binding motifs in key synaptic genes, the relevance of which was functionally confirmed by reporter assays. Collectively, our data suggest a role for YAP1/TAZ-TEAD1/TEAD4 signaling, particularly through TAZ-TEAD4, in regulating synaptic gene expression and acetylcholine receptor clustering at NMJs.
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Affiliation(s)
- Lea Gessler
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Danyil Huraskin
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Yongzhi Jian
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Nane Eiber
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Zhaoyong Hu
- Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Tomasz J Prószyński
- Łukasiewicz Research Network-PORT Polish Center for Technology Development, Wrocław, Poland
| | - Said Hashemolhosseini
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
- Muscle Research Center, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
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3
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Kwan HLR, Chan ZCK, Bi X, Kutkowska J, Prószyński TJ, Chan CB, Lee CW. Nerve-independent formation of membrane infoldings at topologically complex postsynaptic apparatus by caveolin-3. SCIENCE ADVANCES 2023; 9:eadg0183. [PMID: 37327338 PMCID: PMC10275590 DOI: 10.1126/sciadv.adg0183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 05/12/2023] [Indexed: 06/18/2023]
Abstract
Junctional folds are unique membrane specializations developed progressively during the postnatal maturation of vertebrate neuromuscular junctions (NMJs), but how they are formed remains elusive. Previous studies suggested that topologically complex acetylcholine receptor (AChR) clusters in muscle cultures undergo a series of transformations, resembling the postnatal maturation of NMJs in vivo. We first demonstrated the presence of membrane infoldings at AChR clusters in cultured muscles. Live-cell super-resolution imaging further revealed that AChRs are gradually redistributed to the crest regions and spatially segregated from acetylcholinesterase along the elongating membrane infoldings over time. Mechanistically, lipid raft disruption or caveolin-3 knockdown not only inhibits membrane infolding formation at aneural AChR clusters and delays agrin-induced AChR clustering in vitro but also affects junctional fold development at NMJs in vivo. Collectively, this study demonstrated the progressive development of membrane infoldings via nerve-independent, caveolin-3-dependent mechanisms and identified their roles in AChR trafficking and redistribution during the structural maturation of NMJs.
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Affiliation(s)
- Hui-Lam Rachel Kwan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Zora Chui-Kuen Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Xinyi Bi
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong, China
| | - Justyna Kutkowska
- Łukasiewicz Research Network – PORT Polish Center for Technology Development, Wrocław, Poland
| | - Tomasz J. Prószyński
- Łukasiewicz Research Network – PORT Polish Center for Technology Development, Wrocław, Poland
| | - Chi Bun Chan
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong, China
| | - Chi Wai Lee
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- Golden Meditech Centre for NeuroRegeneration Sciences, Hong Kong Baptist University, Hong Kong, China
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Qi Z, Wang S, Xuan A, Gu X, Deng J, Huang C, Zhang L, Yin X. MiR-142a-3p: A novel ACh receptor transcriptional regulator in association with peripheral nerve injury. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 30:325-336. [PMID: 36381585 PMCID: PMC9633872 DOI: 10.1016/j.omtn.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 10/12/2022] [Indexed: 12/15/2022]
Abstract
Long-term denervation leads to the disintegration of nicotinic acetylcholine receptor (nAChR) located at the endplate structure, which translates to deficits in functional activation despite nerve repair. Because of a lack of effective measures to protect AChR expression, we explored the effect of alterations in muscular miR-142a-3p on nAChR. In this study, we constructed a model of miR-142a-3p knockdown by transfecting a miR-142a-3p inhibitor short hairpin RNA (shRNA) into C2C12 myotubes, and we injected this miR-142a-3p inhibitor shRNA into the tibialis anterior (TA) muscle in uninjured mice and in denervated mice by transecting the sciatic nerve. Our results showed that miR-142a-3p knockdown led to an increased number and area of AChR clusters in myotubes in vitro and larger neuromuscular endplates in adult mice. Furthermore, miR-142a-3p knockdown delayed the disintegration of motor endplates after denervation. Last, upon miR-142a-3p knockdown in uninjured and denervated mice, we observed an increase in the mRNA levels of five AChR subunits as well as mRNAs of genes implicated in AChR transcription and AChR clustering. Together, these results suggest that miR-142a-3p may be a potential target for therapeutic intervention to prevent motor endplate degradation following peripheral nerve injury.
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Affiliation(s)
- Zhidan Qi
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Shen Wang
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Ang Xuan
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China
| | - Xinyi Gu
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Jin Deng
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Chen Huang
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Lei Zhang
- Electron Microscopy Analysis Laboratory, Medical and Health Analysis Center, Peking University, Beijing, China,Department of Biophysics, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Xiaofeng Yin
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China,Pizhou People’s Hospital, Jiangsu, China,Corresponding author Xiaofeng Yin, Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China.
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5
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Association of a newly identified lncRNA LNC_000280 with the formation of acetylcholine receptor clusters in vitro. Biochem Biophys Res Commun 2022; 610:8-14. [DOI: 10.1016/j.bbrc.2022.03.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/17/2022] [Accepted: 03/21/2022] [Indexed: 11/22/2022]
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6
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Doss SV, Barbat-Artigas S, Lopes M, Pradhan BS, Prószyński TJ, Robitaille R, Valdez G. Expression and Roles of Lynx1, a Modulator of Cholinergic Transmission, in Skeletal Muscles and Neuromuscular Junctions in Mice. Front Cell Dev Biol 2022; 10:838612. [PMID: 35372356 PMCID: PMC8967655 DOI: 10.3389/fcell.2022.838612] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 01/31/2022] [Indexed: 11/21/2022] Open
Abstract
Lynx1 is a glycosylphosphatidylinositol (GPI)-linked protein shown to affect synaptic plasticity through modulation of nicotinic acetylcholine receptor (nAChR) subtypes in the brain. Because of this function and structural similarity to α-bungarotoxin, which binds muscle-specific nAChRs with high affinity, Lynx1 is a promising candidate for modulating nAChRs in skeletal muscles. However, little is known about the expression and roles of Lynx1 in skeletal muscles and neuromuscular junctions (NMJs). Here, we show that Lynx1 is expressed in skeletal muscles, increases during development, and concentrates at NMJs. We also demonstrate that Lynx1 interacts with muscle-specific nAChR subunits. Additionally, we present data indicating that Lynx1 deletion alters the response of skeletal muscles to cholinergic transmission and their contractile properties. Based on these findings, we asked if Lynx1 deletion affects developing and adult NMJs. Loss of Lynx1 had no effect on NMJs at postnatal day 9 (P9) and moderately increased their size at P21. Thus, Lynx1 plays a minor role in the structural development of NMJs. In 7- and 12-month-old mice lacking Lynx1, there is a marked increase in the incidence of NMJs with age- and disease-associated morphological alterations. The loss of Lynx1 also reduced the size of adult muscle fibers. Despite these effects, Lynx1 deletion did not alter the rate of NMJ reinnervation and stability following motor axon injury. These findings suggest that Lynx1 is not required during fast remodeling of the NMJ, as is the case during reformation following crushing of motor axons and development. Instead, these data indicate that the primary role of Lynx1 may be to maintain the structure and function of adult and aging NMJs.
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Affiliation(s)
- Sydney V. Doss
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI, United States
| | | | - Mikayla Lopes
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI, United States
| | - Bhola Shankar Pradhan
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
- Laboratory of Synaptogenesis, Łukasiewicz Research Network—PORT Polish Center for Technology Development, Wrocław, Poland
| | - Tomasz J. Prószyński
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
- Laboratory of Synaptogenesis, Łukasiewicz Research Network—PORT Polish Center for Technology Development, Wrocław, Poland
| | - Richard Robitaille
- Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
- Centre de Recherche Interdisciplinaire sur le Cerveau et L’Apprentissage (CIRCA), Montreal, QC, Canada
| | - Gregorio Valdez
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI, United States
- Center for Translational Neuroscience, Robert J. and Nancy D. Carney Institute for Brain Science and Brown Institute for Translational Science, Brown University, Providence, RI, United States
- Department of Neurology, Warren Alpert Medical School of Brown University, Providence, RI, United States
- *Correspondence: Gregorio Valdez,
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7
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Pinto C, Pérez V, Mella J, Albistur M, Caprile T, Bronfman FC, Henríquez JP. Transport and Secretion of the Wnt3 Ligand by Motor Neuron-like Cells and Developing Motor Neurons. Biomolecules 2021; 11:biom11121898. [PMID: 34944540 PMCID: PMC8699186 DOI: 10.3390/biom11121898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
The vertebrate neuromuscular junction (NMJ) is formed by a presynaptic motor nerve terminal and a postsynaptic muscle specialization. Cumulative evidence reveals that Wnt ligands secreted by the nerve terminal control crucial steps of NMJ synaptogenesis. For instance, the Wnt3 ligand is expressed by motor neurons at the time of NMJ formation and induces postsynaptic differentiation in recently formed muscle fibers. However, the behavior of presynaptic-derived Wnt ligands at the vertebrate NMJ has not been deeply analyzed. Here, we conducted overexpression experiments to study the expression, distribution, secretion, and function of Wnt3 by transfection of the motor neuron-like NSC-34 cell line and by in ovo electroporation of chick motor neurons. Our findings reveal that Wnt3 is transported along motor axons in vivo following a vesicular-like pattern and reaches the NMJ area. In vitro, we found that endogenous Wnt3 expression increases as the differentiation of NSC-34 cells proceeds. Although NSC-34 cells overexpressing Wnt3 do not modify their morphological differentiation towards a neuronal phenotype, they effectively induce acetylcholine receptor clustering on co-cultured myotubes. These findings support the notion that presynaptic Wnt3 is transported and secreted by motor neurons to induce postsynaptic differentiation in nascent NMJs.
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Affiliation(s)
- Cristina Pinto
- Neuromuscular Studies Laboratory (NeSt Lab), CMA Bio-Bio, Group for the Study of Developmental Processes (GDeP), Department of Cell Biology, Universidad de Concepción, Concepción 4070112, Chile; (C.P.); (V.P.); (J.M.); (M.A.)
| | - Viviana Pérez
- Neuromuscular Studies Laboratory (NeSt Lab), CMA Bio-Bio, Group for the Study of Developmental Processes (GDeP), Department of Cell Biology, Universidad de Concepción, Concepción 4070112, Chile; (C.P.); (V.P.); (J.M.); (M.A.)
| | - Jessica Mella
- Neuromuscular Studies Laboratory (NeSt Lab), CMA Bio-Bio, Group for the Study of Developmental Processes (GDeP), Department of Cell Biology, Universidad de Concepción, Concepción 4070112, Chile; (C.P.); (V.P.); (J.M.); (M.A.)
| | - Miguel Albistur
- Neuromuscular Studies Laboratory (NeSt Lab), CMA Bio-Bio, Group for the Study of Developmental Processes (GDeP), Department of Cell Biology, Universidad de Concepción, Concepción 4070112, Chile; (C.P.); (V.P.); (J.M.); (M.A.)
| | - Teresa Caprile
- Axon Guidance Laboratory, Group for the Study of Developmental Processes (GDeP), Department of Cell Biology, Universidad de Concepción, Concepción 4070112, Chile;
| | - Francisca C. Bronfman
- Institute of Biomedical Sciences (ICB), Faculty of Medicine and Faculty of Life Science, Universidad Andres Bello, Santiago 8320000, Chile;
- CARE Biomedical Research Center, Pontificia Universidad Católica de Chile, Santiago 8320000, Chile
| | - Juan Pablo Henríquez
- Neuromuscular Studies Laboratory (NeSt Lab), CMA Bio-Bio, Group for the Study of Developmental Processes (GDeP), Department of Cell Biology, Universidad de Concepción, Concepción 4070112, Chile; (C.P.); (V.P.); (J.M.); (M.A.)
- Correspondence: ; Tel.: +56-41-220-3492
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Tks5 Regulates Synaptic Podosome Formation and Stabilization of the Postsynaptic Machinery at the Neuromuscular Junction. Int J Mol Sci 2021; 22:ijms222112051. [PMID: 34769479 PMCID: PMC8585010 DOI: 10.3390/ijms222112051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 11/16/2022] Open
Abstract
Currently, the etiology of many neuromuscular disorders remains unknown. Many of them are characterized by aberrations in the maturation of the neuromuscular junction (NMJ) postsynaptic machinery. Unfortunately, the molecular factors involved in this process are still largely unknown, which poses a great challenge for identifying potential therapeutic targets. Here, we identified Tks5 as a novel interactor of αdystrobrevin-1, which is a crucial component of the NMJ postsynaptic machinery. Tks5 has been previously shown in cancer cells to be an important regulator of actin-rich structures known as invadosomes. However, a role of this scaffold protein at a synapse has never been studied. We show that Tks5 is crucial for remodeling of the NMJ postsynaptic machinery by regulating the organization of structures similar to the invadosomes, known as synaptic podosomes. Additionally, it is involved in the maintenance of the integrity of acetylcholine receptor (AChR) clusters and regulation of their turnover. Lastly, our data indicate that these Tks5 functions may be mediated by its involvement in recruitment of actin filaments to the postsynaptic machinery. Collectively, we show for the first time that the Tks5 protein is involved in regulation of the postsynaptic machinery.
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9
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Sawada H, Kurimoto S, Tokutake K, Saeki S, Hirata H. Optimal conditions for graft survival and reinnervation of denervated muscles after embryonic motoneuron transplantation into peripheral nerves undergoing Wallerian degeneration. J Tissue Eng Regen Med 2021; 15:763-775. [PMID: 34030216 DOI: 10.1002/term.3223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 05/16/2021] [Accepted: 05/17/2021] [Indexed: 12/26/2022]
Abstract
Motoneuron transplantation into peripheral nerves undergoing Wallerian degeneration may have applications in treating diseases causing muscle paralysis. We investigated whether functional reinnervation of denervated muscle could be achieved by early or delayed transplantation after denervation. Adult rats were assigned to six groups with increasing denervation periods (0, 1, 4, 8, 12, and 24 weeks) before inoculation with culture medium containing (transplantation group) or lacking (surgical control group) dissociated embryonic motoneurons into the peroneal nerve. Electrophysiological and tissue analyses were performed 3 months after transplantation. Reinnervation of denervated muscles significantly increased relative muscle weight in the transplantation group compared with the surgical control group for denervation periods of 1 week (0.042% ± 0.0031% vs. 0.032% ± 0.0020%, respectively; p = 0.009), 4 weeks (0.044% ± 0.0069% vs. 0.026% ± 0.0045%, respectively; p = 0.0023), and 8 weeks (0.044% ± 0.0029% vs. 0.026% ± 0.0008%, respectively; p = 0.0023). The ratios of reinnervated muscle contractile forces to naïve muscle in the 0, 1, 4, 8, and 12 weeks transplantation groups were 3.79%, 18.99%, 8.05%, 6.30%, and 5.80%, respectively, indicating that these forces were sufficient for walking. The optimal implantation time for transplantation of motoneurons into the peripheral nerve was 1 week after nerve transection. However, the neurons transplanted 24 weeks after denervation survived and regenerated axons. These results indicated that there is time for preparing cells for transplantation in regenerative medicine and suggested that our method may be useful for paralysed muscles that are not expected to recover with current treatment.
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Affiliation(s)
- Hideyoshi Sawada
- Department of Hand Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shigeru Kurimoto
- Department of Hand Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Katsuhiro Tokutake
- Department of Hand Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Sota Saeki
- Department of Hand Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hitoshi Hirata
- Department of Hand Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Alvarez-Suarez P, Nowak N, Protasiuk-Filipunas A, Yamazaki H, Prószyński TJ, Gawor M. Drebrin Regulates Acetylcholine Receptor Clustering and Organization of Microtubules at the Postsynaptic Machinery. Int J Mol Sci 2021; 22:9387. [PMID: 34502296 PMCID: PMC8430516 DOI: 10.3390/ijms22179387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 01/07/2023] Open
Abstract
Proper muscle function depends on the neuromuscular junctions (NMJs), which mature postnatally to complex "pretzel-like" structures, allowing for effective synaptic transmission. Postsynaptic acetylcholine receptors (AChRs) at NMJs are anchored in the actin cytoskeleton and clustered by the scaffold protein rapsyn, recruiting various actin-organizing proteins. Mechanisms driving the maturation of the postsynaptic machinery and regulating rapsyn interactions with the cytoskeleton are still poorly understood. Drebrin is an actin and microtubule cross-linker essential for the functioning of the synapses in the brain, but its role at NMJs remains elusive. We used immunohistochemistry, RNA interference, drebrin inhibitor 3,5-bis-trifluoromethyl pyrazole (BTP2) and co-immunopreciptation to explore the role of this protein at the postsynaptic machinery. We identify drebrin as a postsynaptic protein colocalizing with the AChRs both in vitro and in vivo. We also show that drebrin is enriched at synaptic podosomes. Downregulation of drebrin or blocking its interaction with actin in cultured myotubes impairs the organization of AChR clusters and the cluster-associated microtubule network. Finally, we demonstrate that drebrin interacts with rapsyn and a drebrin interactor, plus-end-tracking protein EB3. Our results reveal an interplay between drebrin and cluster-stabilizing machinery involving rapsyn, actin cytoskeleton, and microtubules.
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Affiliation(s)
- Paloma Alvarez-Suarez
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (P.A.-S.); (N.N.); (A.P.-F.); (T.J.P.)
| | - Natalia Nowak
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (P.A.-S.); (N.N.); (A.P.-F.); (T.J.P.)
| | - Anna Protasiuk-Filipunas
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (P.A.-S.); (N.N.); (A.P.-F.); (T.J.P.)
| | - Hiroyuki Yamazaki
- Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan;
| | - Tomasz J. Prószyński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (P.A.-S.); (N.N.); (A.P.-F.); (T.J.P.)
| | - Marta Gawor
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (P.A.-S.); (N.N.); (A.P.-F.); (T.J.P.)
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11
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Zelada D, Barrantes FJ, Henríquez JP. Lithium causes differential effects on postsynaptic stability in normal and denervated neuromuscular synapses. Sci Rep 2021; 11:17285. [PMID: 34446751 PMCID: PMC8390761 DOI: 10.1038/s41598-021-96708-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 08/06/2021] [Indexed: 11/12/2022] Open
Abstract
Lithium chloride has been widely used as a therapeutic mood stabilizer. Although cumulative evidence suggests that lithium plays modulatory effects on postsynaptic receptors, the underlying mechanism by which lithium regulates synaptic transmission has not been fully elucidated. In this work, by using the advantageous neuromuscular synapse, we evaluated the effect of lithium on the stability of postsynaptic nicotinic acetylcholine receptors (nAChRs) in vivo. We found that in normally innervated neuromuscular synapses, lithium chloride significantly decreased the turnover of nAChRs by reducing their internalization. A similar response was observed in CHO-K1/A5 cells expressing the adult muscle-type nAChRs. Strikingly, in denervated neuromuscular synapses, lithium led to enhanced nAChR turnover and density by increasing the incorporation of new nAChRs. Lithium also potentiated the formation of unstable nAChR clusters in non-synaptic regions of denervated muscle fibres. We found that denervation-dependent re-expression of the foetal nAChR γ-subunit was not altered by lithium. However, while denervation inhibits the distribution of β-catenin within endplates, lithium-treated fibres retain β-catenin staining in specific foci of the synaptic region. Collectively, our data reveal that lithium treatment differentially affects the stability of postsynaptic receptors in normal and denervated neuromuscular synapses in vivo, thus providing novel insights into the regulatory effects of lithium on synaptic organization and extending its potential therapeutic use in conditions affecting the peripheral nervous system.
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Affiliation(s)
- Diego Zelada
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, CMA Bio-Bio, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Francisco J Barrantes
- Pontificia Universidad Católica Argentina (UCA)-Scientific and Technological Research Council of Argentina (CONICET), Buenos Aires, Argentina
| | - Juan Pablo Henríquez
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, CMA Bio-Bio, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
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12
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Brunetti J, Koenig S, Monnier A, Frieden M. Nanopattern surface improves cultured human myotube maturation. Skelet Muscle 2021; 11:12. [PMID: 33952323 PMCID: PMC8097894 DOI: 10.1186/s13395-021-00268-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/19/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In vitro maturation of human primary myoblasts using 2D culture remains a challenging process and leads to immature fibers with poor internal organization and function. This would however represent a valuable system to study muscle physiology or pathophysiology from patient myoblasts, at a single-cell level. METHODS Human primary myoblasts were cultured on 800-nm wide striated surface between two layers of Matrigel, and in a media supplemented with an inhibitor of TGFβ receptor. Gene expression, immunofluorescence, and Ca2+ measurements upon electrical stimulations were performed at various time points during maturation to assess the organization and function of the myotubes. RESULTS We show that after 10 days in culture, myotubes display numerous functional acetylcholine receptor clusters and express the adult isoforms of myosin heavy chain and dihydropyridine receptor. In addition, the myotubes are internally well organized with striations of α-actinin and STIM1, and occasionally ryanodine receptor 1. We also demonstrate that the myotubes present robust Ca2+ responses to repetitive electrical stimulations. CONCLUSION The present method describes a fast and efficient system to obtain well matured and functional myotubes in 2D culture allowing thorough analysis of single-cell Ca2+ signals.
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Affiliation(s)
- Jessica Brunetti
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Stéphane Koenig
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Arthur Monnier
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Maud Frieden
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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13
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Stoklund Dittlau K, Krasnow EN, Fumagalli L, Vandoorne T, Baatsen P, Kerstens A, Giacomazzi G, Pavie B, Rossaert E, Beckers J, Sampaolesi M, Van Damme P, Van Den Bosch L. Human motor units in microfluidic devices are impaired by FUS mutations and improved by HDAC6 inhibition. Stem Cell Reports 2021; 16:2213-2227. [PMID: 33891869 PMCID: PMC8452598 DOI: 10.1016/j.stemcr.2021.03.029] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 12/13/2022] Open
Abstract
Neuromuscular junctions (NMJs) ensure communication between motor neurons (MNs) and muscle; however, in MN disorders, such as amyotrophic lateral sclerosis (ALS), NMJs degenerate resulting in muscle atrophy. The aim of this study was to establish a versatile and reproducible in vitro model of a human motor unit to investigate the effects of ALS-causing mutations. Therefore, we generated a co-culture of human induced pluripotent stem cell (iPSC)-derived MNs and human primary mesoangioblast-derived myotubes in microfluidic devices. A chemotactic and volumetric gradient facilitated the growth of MN neurites through microgrooves resulting in the interaction with myotubes and the formation of NMJs. We observed that ALS-causing FUS mutations resulted in reduced neurite outgrowth as well as an impaired neurite regrowth upon axotomy. NMJ numbers were likewise reduced in the FUS-ALS model. Interestingly, the selective HDAC6 inhibitor, Tubastatin A, improved the neurite outgrowth, regrowth, and NMJ morphology, prompting HDAC6 inhibition as a potential therapeutic strategy for ALS. Human motor units with functional NMJs can be generated using microfluidic devices FUS-ALS motor units display impaired neurite regrowth, outgrowth and NMJ numbers HDAC6 inhibition alleviate FUS-ALS motor unit pathology in vitro
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Affiliation(s)
- Katarina Stoklund Dittlau
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium
| | - Emily N Krasnow
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium
| | - Laura Fumagalli
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium
| | - Tijs Vandoorne
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium
| | - Pieter Baatsen
- VIB, Center for Brain & Disease Research, Research Group Molecular Neurobiology, Leuven, Belgium; KU Leuven - University of Leuven, VIB Bio Imaging Core, Leuven, Belgium
| | - Axelle Kerstens
- VIB, Center for Brain & Disease Research, Research Group Molecular Neurobiology, Leuven, Belgium; KU Leuven - University of Leuven, VIB Bio Imaging Core, Leuven, Belgium
| | - Giorgia Giacomazzi
- KU Leuven - University of Leuven, Department of Development and Regeneration, Stem Cell and Developmental Biology, Leuven, Belgium
| | - Benjamin Pavie
- VIB, Center for Brain & Disease Research, Research Group Molecular Neurobiology, Leuven, Belgium; KU Leuven - University of Leuven, VIB Bio Imaging Core, Leuven, Belgium
| | - Elisabeth Rossaert
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium
| | - Jimmy Beckers
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium
| | - Maurilio Sampaolesi
- KU Leuven - University of Leuven, Department of Development and Regeneration, Stem Cell and Developmental Biology, Leuven, Belgium
| | - Philip Van Damme
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium; University Hospitals Leuven, Department of Neurology, Leuven, Belgium
| | - Ludo Van Den Bosch
- KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute, Leuven, Belgium; VIB, Center for Brain & Disease Research, Laboratory of Neurobiology, Leuven, Belgium.
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14
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Wang M, Kleele T, Xiao Y, Plucinska G, Avramopoulos P, Engelhardt S, Schwab MH, Kneussel M, Czopka T, Sherman DL, Brophy PJ, Misgeld T, Brill MS. Completion of neuronal remodeling prompts myelination along developing motor axon branches. J Cell Biol 2021; 220:e201911114. [PMID: 33538762 PMCID: PMC7868780 DOI: 10.1083/jcb.201911114] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 11/20/2020] [Accepted: 01/04/2021] [Indexed: 12/20/2022] Open
Abstract
Neuronal remodeling and myelination are two fundamental processes during neurodevelopment. How they influence each other remains largely unknown, even though their coordinated execution is critical for circuit function and often disrupted in neuropsychiatric disorders. It is unclear whether myelination stabilizes axon branches during remodeling or whether ongoing remodeling delays myelination. By modulating synaptic transmission, cytoskeletal dynamics, and axonal transport in mouse motor axons, we show that local axon remodeling delays myelination onset and node formation. Conversely, glial differentiation does not determine the outcome of axon remodeling. Delayed myelination is not due to a limited supply of structural components of the axon-glial unit but rather is triggered by increased transport of signaling factors that initiate myelination, such as neuregulin. Further, transport of promyelinating signals is regulated via local cytoskeletal maturation related to activity-dependent competition. Our study reveals an axon branch-specific fine-tuning mechanism that locally coordinates axon remodeling and myelination.
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Affiliation(s)
- Mengzhe Wang
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Tatjana Kleele
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Yan Xiao
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Gabriela Plucinska
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Petros Avramopoulos
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
- German Center for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, Munich, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
- German Center for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, Munich, Germany
| | - Markus H. Schwab
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Matthias Kneussel
- University Medical Center Hamburg-Eppendorf, Center for Molecular Neurobiology (ZMNH), Institute for Molecular Neurogenetics, Hamburg, Germany
| | - Tim Czopka
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Diane L. Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Peter J. Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas Misgeld
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Monika S. Brill
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
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15
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Osseni A, Ravel-Chapuis A, Thomas JL, Gache V, Schaeffer L, Jasmin BJ. HDAC6 regulates microtubule stability and clustering of AChRs at neuromuscular junctions. J Cell Biol 2021; 219:151966. [PMID: 32697819 PMCID: PMC7401804 DOI: 10.1083/jcb.201901099] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/20/2020] [Accepted: 05/08/2020] [Indexed: 12/11/2022] Open
Abstract
Microtubules (MTs) are known to be post-translationally modified at the neuromuscular junction (NMJ), hence increasing their stability. To date however, the function(s) of the dynamic MT network and its relative stability in the formation and maintenance of NMJs remain poorly described. Stabilization of the MT is dependent in part on its acetylation status, and HDAC6 is capable of reversing this post-translational modification. Here, we report that HDAC6 preferentially accumulates at NMJs and that it contributes to the organization and the stability of NMJs. Indeed, pharmacological inhibition of HDAC6 protects against MT disorganization and reduces the size of acetylcholine receptor (AChR) clusters. Moreover, the endogenous HDAC6 inhibitor paxillin interacts with HDAC6 in skeletal muscle cells, colocalizes with AChR aggregates, and regulates the formation of AChR. Our findings indicate that the focal insertion of AChRs into the postsynaptic membrane is regulated by stable MTs and highlight how an MT/HDAC6/paxillin axis participates in the regulation of AChR insertion and removal to control the structure of NMJs.
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Affiliation(s)
- Alexis Osseni
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Éric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Aymeric Ravel-Chapuis
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Éric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Jean-Luc Thomas
- Institut NeuroMyoGene, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale Unité 1217, Université de Lyon, Lyon, France
| | - Vincent Gache
- Institut NeuroMyoGene, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale Unité 1217, Université de Lyon, Lyon, France
| | - Laurent Schaeffer
- Institut NeuroMyoGene, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale Unité 1217, Université de Lyon, Lyon, France.,Centre de Biotechnologie Cellulaire, Hospices Civils de Lyon, Lyon, France
| | - Bernard J Jasmin
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Éric Poulin Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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16
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Paz ML, Barrantes FJ. Cholesterol in myasthenia gravis. Arch Biochem Biophys 2021; 701:108788. [PMID: 33548213 DOI: 10.1016/j.abb.2021.108788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 01/13/2021] [Accepted: 01/26/2021] [Indexed: 01/03/2023]
Abstract
The cholinergic neuromuscular junction is the paradigm peripheral synapse between a motor neuron nerve ending and a skeletal muscle fiber. In vertebrates, acetylcholine is released from the presynaptic site and binds to the nicotinic acetylcholine receptor at the postsynaptic membrane. A variety of pathologies among which myasthenia gravis stands out can impact on this rapid and efficient signaling mechanism, including autoimmune diseases affecting the nicotinic receptor or other synaptic proteins. Cholesterol is an essential component of biomembranes and is particularly rich at the postsynaptic membrane, where it interacts with and modulates many properties of the nicotinic receptor. The profound changes inflicted by myasthenia gravis on the postsynaptic membrane necessarily involve cholesterol. This review analyzes some aspects of myasthenia gravis pathophysiology and associated postsynaptic membrane dysfunction, including dysregulation of cholesterol metabolism in the myocyte brought about by antibody-receptor interactions. In addition, given the extensive therapeutic use of statins as the typical cholesterol-lowering drugs, we discuss their effects on skeletal muscle and the possible implications for MG patients under chronic treatment with this type of compound.
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Affiliation(s)
- Mariela L Paz
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Inmunología, Buenos Aires, Argentina; CONICET, Universidad de Buenos Aires, Instituto de Estudios de la Inmunidad Humoral "Prof. Dr. Ricardo A. Margni" (IDEHU), Buenos Aires, Argentina
| | - Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute (BIOMED), UCA, CONICET, Av. Alicia Moreau de Justo 1600, C1107AFF, Buenos Aires, Argentina.
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17
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Zelada D, Bermedo-García F, Collao N, Henríquez JP. Motor function recovery: deciphering a regenerative niche at the neuromuscular synapse. Biol Rev Camb Philos Soc 2020; 96:752-766. [PMID: 33336525 PMCID: PMC7986695 DOI: 10.1111/brv.12675] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 11/20/2020] [Accepted: 11/25/2020] [Indexed: 12/13/2022]
Abstract
The coordinated movement of many organisms relies on efficient nerve–muscle communication at the neuromuscular junction (NMJ), a peripheral synapse composed of a presynaptic motor axon terminal, a postsynaptic muscle specialization, and non‐myelinating terminal Schwann cells. NMJ dysfunctions are caused by traumatic spinal cord or peripheral nerve injuries as well as by severe motor pathologies. Compared to the central nervous system, the peripheral nervous system displays remarkable regenerating abilities; however, this capacity is limited by the denervation time frame and depends on the establishment of permissive regenerative niches. At the injury site, detailed information is available regarding the cells, molecules, and mechanisms involved in nerve regeneration and repair. However, a regenerative niche at the final functional step of peripheral motor innervation, i.e. at the mature neuromuscular synapse, has not been deciphered. In this review, we integrate classic and recent evidence describing the cells and molecules that could orchestrate a dynamic ecosystem to accomplish successful NMJ regeneration. We propose that such a regenerative niche must ensure at least two fundamental steps for successful NMJ regeneration: the proper arrival of incoming regenerating axons to denervated postsynaptic muscle domains, and the resilience of those postsynaptic domains, in morphological and functional terms. We here describe and combine the main cellular and molecular responses involved in each of these steps as potential targets to help successful NMJ regeneration.
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Affiliation(s)
- Diego Zelada
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Faculty of Biological Sciences, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Francisca Bermedo-García
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Faculty of Biological Sciences, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Nicolás Collao
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Faculty of Biological Sciences, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Juan P Henríquez
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Faculty of Biological Sciences, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Casilla 160-C, Concepción, Chile
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18
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Petrany MJ, Swoboda CO, Sun C, Chetal K, Chen X, Weirauch MT, Salomonis N, Millay DP. Single-nucleus RNA-seq identifies transcriptional heterogeneity in multinucleated skeletal myofibers. Nat Commun 2020; 11:6374. [PMID: 33311464 PMCID: PMC7733460 DOI: 10.1038/s41467-020-20063-w] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 11/09/2020] [Indexed: 02/06/2023] Open
Abstract
While the majority of cells contain a single nucleus, cell types such as trophoblasts, osteoclasts, and skeletal myofibers require multinucleation. One advantage of multinucleation can be the assignment of distinct functions to different nuclei, but comprehensive interrogation of transcriptional heterogeneity within multinucleated tissues has been challenging due to the presence of a shared cytoplasm. Here, we utilized single-nucleus RNA-sequencing (snRNA-seq) to determine the extent of transcriptional diversity within multinucleated skeletal myofibers. Nuclei from mouse skeletal muscle were profiled across the lifespan, which revealed the presence of distinct myonuclear populations emerging in postnatal development as well as aging muscle. Our datasets also provided a platform for discovery of genes associated with rare specialized regions of the muscle cell, including markers of the myotendinous junction and functionally validated factors expressed at the neuromuscular junction. These findings reveal that myonuclei within syncytial muscle fibers possess distinct transcriptional profiles that regulate muscle biology.
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Affiliation(s)
- Michael J Petrany
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Casey O Swoboda
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Chengyi Sun
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Kashish Chetal
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Xiaoting Chen
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Matthew T Weirauch
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Nathan Salomonis
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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19
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Rodríguez Cruz PM, Cossins J, Beeson D, Vincent A. The Neuromuscular Junction in Health and Disease: Molecular Mechanisms Governing Synaptic Formation and Homeostasis. Front Mol Neurosci 2020; 13:610964. [PMID: 33343299 PMCID: PMC7744297 DOI: 10.3389/fnmol.2020.610964] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022] Open
Abstract
The neuromuscular junction (NMJ) is a highly specialized synapse between a motor neuron nerve terminal and its muscle fiber that are responsible for converting electrical impulses generated by the motor neuron into electrical activity in the muscle fibers. On arrival of the motor nerve action potential, calcium enters the presynaptic terminal, which leads to the release of the neurotransmitter acetylcholine (ACh). ACh crosses the synaptic gap and binds to ACh receptors (AChRs) tightly clustered on the surface of the muscle fiber; this leads to the endplate potential which initiates the muscle action potential that results in muscle contraction. This is a simplified version of the events in neuromuscular transmission that take place within milliseconds, and are dependent on a tiny but highly structured NMJ. Much of this review is devoted to describing in more detail the development, maturation, maintenance and regeneration of the NMJ, but first we describe briefly the most important molecules involved and the conditions that affect their numbers and function. Most important clinically worldwide, are myasthenia gravis (MG), the Lambert-Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndromes (CMS), each of which causes specific molecular defects. In addition, we mention the neurotoxins from bacteria, snakes and many other species that interfere with neuromuscular transmission and cause potentially fatal diseases, but have also provided useful probes for investigating neuromuscular transmission. There are also changes in NMJ structure and function in motor neuron disease, spinal muscle atrophy and sarcopenia that are likely to be secondary but might provide treatment targets. The NMJ is one of the best studied and most disease-prone synapses in the nervous system and it is amenable to in vivo and ex vivo investigation and to systemic therapies that can help restore normal function.
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Affiliation(s)
- Pedro M. Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Judith Cossins
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
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20
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Zhao Y, Peng HB. Roles of tyrosine kinases and phosphatases in the formation and dispersal of acetylcholine receptor clusters. Neurosci Lett 2020; 733:135054. [PMID: 32428606 DOI: 10.1016/j.neulet.2020.135054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 10/24/2022]
Abstract
The formation of acetylcholine receptor (AChR) clusters at the postsynaptic muscle membrane in response to motor innervation is a key event in the development of the neuromuscular junction. The synaptic AChR clustering process is initiated by motor axon-released agrin, which activates a tyrosine kinase-based signaling pathway to cause AChR aggregation. In cultured muscle cells, AChR clustering is elicited by diverse nonneural signals, and this process is also mediated by tyrosine kinases. Conversely, the formation of new AChR clusters induced by innervation or nonneural stimuli is unfailingly associated with the dispersal of pre-existing AChR clusters, and this process is mediated by tyrosine phosphatases. In this review, we address how local kinase activation leads to global phosphatase action in muscle. More specifically, we discuss the roles of Src kinase and the SH2 domain-containing tyrosine phosphatase Shp-2 in establishing a regenerative mechanism to propagate the AChR cluster dispersing signal extrasynaptically and in defining the boundary of cluster formation subsynaptically.
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Affiliation(s)
- Yang Zhao
- Division of Life Science, the Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region.
| | - H Benjamin Peng
- Division of Life Science, the Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region; College of Life Science, National Tsing Hua University, Hsinchu, Taiwan, ROC.
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21
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Grp94 Regulates the Recruitment of Aneural AChR Clusters for the Assembly of Postsynaptic Specializations by Modulating ADF/Cofilin Activity and Turnover. eNeuro 2020; 7:ENEURO.0025-20.2020. [PMID: 32747457 PMCID: PMC7540925 DOI: 10.1523/eneuro.0025-20.2020] [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: 01/26/2020] [Revised: 07/27/2020] [Accepted: 07/27/2020] [Indexed: 11/21/2022] Open
Abstract
Temperature is a physiological factor that affects neuronal growth and synaptic homeostasis at the invertebrate neuromuscular junctions (NMJs); however, whether temperature stress could also regulate the structure and function of the vertebrate NMJs remains unclear. In this study, we use Xenopus laevis primary cultures as a vertebrate model system for investigating the involvement of heat shock protein 90 (HSP90) family of stress proteins in NMJ development. First, cold temperature treatment or HSP90 inhibition attenuates the formation of aneural acetylcholine receptor (AChR) clusters, but increases their stability after they are formed, in cultured muscles. HSP90 inhibition specifically affects the stability of aneural AChR clusters and their associated intracellular scaffolding protein rapsyn, instead of causing a global change in cell metabolism and protein expression in Xenopus muscle cultures. Upon synaptogenic stimulation, a specific HSP90 family member, glucose-regulated protein 94 (Grp94), modulates the phosphorylation and dynamic turnover of actin depolymerizing factor (ADF)/cofilin at aneural AChR clusters, leading to the recruitment of AChR molecules from aneural clusters to the assembly of agrin-induced postsynaptic specializations. Finally, postsynaptic Grp94 knock-down significantly inhibits nerve-induced AChR clustering and postsynaptic activity in nerve-muscle co-cultures as demonstrated by live-cell imaging and electrophysiological recording, respectively. Collectively, this study suggests that temperature-dependent alteration in Grp94 expression and activity inhibits the assembly of postsynaptic specializations through modulating ADF/cofilin phosphorylation and activity at aneural AChR clusters, which prevents AChR molecules from being recruited to the postsynaptic sites via actin-dependent vesicular trafficking, at developing vertebrate NMJs.
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22
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Brzoska E, Kalkowski L, Kowalski K, Michalski P, Kowalczyk P, Mierzejewski B, Walczak P, Ciemerych MA, Janowski M. Muscular Contribution to Adolescent Idiopathic Scoliosis from the Perspective of Stem Cell-Based Regenerative Medicine. Stem Cells Dev 2020; 28:1059-1077. [PMID: 31170887 DOI: 10.1089/scd.2019.0073] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Adolescent idiopathic scoliosis (AIS) is a relatively frequent disease within a range 0.5%-5.0% of population, with higher frequency in females. While a resultant spinal deformity is usually medically benign condition, it produces far going psychosocial consequences, which warrant attention. The etiology of AIS is unknown and current therapeutic approaches are symptomatic only, and frequently inconvenient or invasive. Muscular contribution to AIS is widely recognized, although it did not translate to clinical routine as yet. Muscle asymmetry has been documented by pathological examinations as well as systemic muscle disorders frequently leading to scoliosis. It has been also reported numerous genetic, metabolic and radiological alterations in patients with AIS, which are linked to muscular and neuromuscular aspects. Therefore, muscles might be considered an attractive and still insufficiently exploited therapeutic target for AIS. Stem cell-based regenerative medicine is rapidly gaining momentum based on the tremendous progress in understanding of developmental biology. It comes also with a toolbox of various stem cells such as satellite cells or mesenchymal stem cells, which could be transplanted; also, the knowledge acquired in research on regenerative medicine can be applied to manipulation of endogenous stem cells to obtain desired therapeutic goals. Importantly, paravertebral muscles are located relatively superficially; therefore, they can be an easy target for minimally invasive approaches to treatment of AIS. It comes in pair with a fast progress in image guidance, which allows for precise delivery of therapeutic agents, including stem cells to various organs such as brain, muscles, and others. Summing up, it seems that there is a link between AIS, muscles, and stem cells, which might be worth of further investigations with a long-term goal of setting foundations for eventual bench-to-bedside translation.
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Affiliation(s)
- Edyta Brzoska
- 1Department of Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Lukasz Kalkowski
- 2Department of Neurology and Neurosurgery, Faculty of Medical Sciences, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - Kamil Kowalski
- 1Department of Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Pawel Michalski
- 3Spine Surgery Department, Institute of Mother and Child, Warsaw, Poland
| | - Pawel Kowalczyk
- 4Department of Neurosurgery, Children's Memorial Health Institute, Warsaw, Poland
| | - Bartosz Mierzejewski
- 1Department of Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Piotr Walczak
- 5Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,6Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Maria A Ciemerych
- 1Department of Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Miroslaw Janowski
- 5Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,6Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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23
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Florkowska A, Meszka I, Zawada M, Legutko D, Proszynski TJ, Janczyk-Ilach K, Streminska W, Ciemerych MA, Grabowska I. Pax7 as molecular switch regulating early and advanced stages of myogenic mouse ESC differentiation in teratomas. Stem Cell Res Ther 2020; 11:238. [PMID: 32552916 PMCID: PMC7301568 DOI: 10.1186/s13287-020-01742-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/15/2020] [Accepted: 05/25/2020] [Indexed: 12/17/2022] Open
Abstract
Background Pluripotent stem cells present the ability to self-renew and undergo differentiation into any cell type building an organism. Importantly, a lot of evidence on embryonic stem cell (ESC) differentiation comes from in vitro studies. However, ESCs cultured in vitro do not necessarily behave as cells differentiating in vivo. For this reason, we used teratomas to study early and advanced stages of in vivo ESC myogenic differentiation and the role of Pax7 in this process. Pax7 transcription factor plays a crucial role in the formation and differentiation of skeletal muscle precursor cells during embryonic development. It controls the expression of other myogenic regulators and also acts as an anti-apoptotic factor. It is also involved in the formation and maintenance of satellite cell population. Methods In vivo approach we used involved generation and analysis of pluripotent stem cell-derived teratomas. Such model allows to analyze early and also terminal stages of tissue differentiation, for example, terminal stages of myogenesis, including the formation of innervated and vascularized mature myofibers. Results We determined how the lack of Pax7 function affects the generation of different myofiber types. In Pax7−/− teratomas, the skeletal muscle tissue occupied significantly smaller area, as compared to Pax7+/+ ones. The proportion of myofibers expressing Myh3 and Myh2b did not differ between Pax7+/+ and Pax7−/− teratomas. However, the area of Myh7 and Myh2a myofibers was significantly lower in Pax7−/− ones. Molecular characteristic of skeletal muscles revealed that the levels of mRNAs coding Myh isoforms were significantly lower in Pax7−/− teratomas. The level of mRNAs encoding Pax3 was significantly higher, while the expression of Nfix, Eno3, Mck, Mef2a, and Itga7 was significantly lower in Pax7−/− teratomas, as compared to Pax7+/+ ones. We proved that the number of satellite cells in Pax7−/− teratomas was significantly reduced. Finally, analysis of neuromuscular junction localization in samples prepared with the iDISCO method confirmed that the organization of neuromuscular junctions in Pax7−/− teratomas was impaired. Conclusions Pax7−/− ESCs differentiate in vivo to embryonic myoblasts more readily than Pax7+/+ cells. In the absence of functional Pax7, initiation of myogenic differentiation is facilitated, and as a result, the expression of mesoderm embryonic myoblast markers is upregulated. However, in the absence of functional Pax7 neuromuscular junctions, formation is abnormal, what results in lower differentiation potential of Pax7−/− ESCs during advanced stages of myogenesis.
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Affiliation(s)
- Anita Florkowska
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Igor Meszka
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Magdalena Zawada
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Diana Legutko
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland.,Laboratory of Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Tomasz J Proszynski
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.,Present Address: Lukasiewicz Research Network - PORT Polish Center for Technology Development, Wroclaw, Poland
| | - Katarzyna Janczyk-Ilach
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Wladyslawa Streminska
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Maria A Ciemerych
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Iwona Grabowska
- Department of Cytology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland.
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24
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Abstract
Thirty to fifty percent of patients with acetylcholine receptor (AChR) antibody (Ab)-negative myasthenia gravis (MG) have Abs to muscle specific kinase (MuSK) and are referred to as having MuSK-MG. MuSK is a 100 kD single-pass post-synaptic transmembrane receptor tyrosine kinase crucial to the development and maintenance of the neuromuscular junction. The Abs in MuSK-MG are predominantly of the IgG4 immunoglobulin subclass. MuSK-MG differs from AChR-MG, in exhibiting more focal muscle involvement, including neck, shoulder, facial and bulbar-innervated muscles, as well as wasting of the involved muscles. MuSK-MG is highly associated with the HLA DR14-DQ5 haplotype and occurs predominantly in females with onset in the fourth decade of life. Some of the standard treatments of AChR-MG have been found to have limited effectiveness in MuSK-MG, including thymectomy and cholinesterase inhibitors. Therefore, current treatment involves immunosuppression, primarily by corticosteroids. In addition, patients respond especially well to B cell depletion agents, e.g., rituximab, with long-term remissions. Future treatments will likely derive from the ongoing analysis of the pathogenic mechanisms underlying this disease, including histologic and physiologic studies of the neuromuscular junction in patients as well as information derived from the development and study of animal models of the disease.
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Affiliation(s)
| | - David P. Richman
- Department of Neurology, University of California, Davis, Davis, CA, United States
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25
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Hastings RL, Massopust RT, Haddix SG, Lee YI, Thompson WJ. Exclusive vital labeling of myonuclei for studying myonuclear arrangement in mouse skeletal muscle tissue. Skelet Muscle 2020; 10:15. [PMID: 32381068 PMCID: PMC7204059 DOI: 10.1186/s13395-020-00233-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 04/23/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The arrangement of myonuclei in skeletal muscle tissue has long been used as a biomarker for muscle health, but there is a dearth of in vivo exploration of potential effects of myonuclear organization on the function and regeneration of skeletal muscle because traditional nuclear stains are performed on postmortem tissue. Therefore, we sought a transgenic method to produce a selective and persistent myonuclear label in whole muscles of living mice. METHODS We bred together a mouse line with skeletal muscle fiber-selective expression of Cre recombinase and a second mouse line with a Cre-inducible fluorescently tagged histone protein to generate a mouse line that produces a myonuclear label suitable for vital imaging and histology of fixed tissue. We tested the effectiveness of this vital label in three conditions known to generate abnormal myonuclear positioning. First, we injured myofibers of young mice with cardiotoxin. Second, this nuclear label was bred into a murine model of Duchenne muscular dystrophy. Finally, we examined old mice from this line that have undergone the natural aging process. Welch's t test was used to compare wild type and transgenic mice. RESULTS The resulting mouse line transgenically produces a vital red fluorescent label of myonuclei, which facilitates their in vivo imaging in skeletal muscle tissue. Transgenic fluorescent labeling of myonuclei has no significant effect on skeletal muscle function, as determined by twitch and tetanic force recordings. In each muscle examined, including those under damaged, dystrophic, and aged conditions, the labeled myonuclei exhibit morphology consistent with established literature, and reveal a specialized arrangement of subsynaptic myonuclei at the neuromuscular junction. CONCLUSIONS Taken together, our results demonstrate that this mouse line provides a versatile tool to selectively visualize myonuclei within both living and fixed preparations of healthy, injured, diseased, and aged muscles.
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Affiliation(s)
- Robert Louis Hastings
- Texas A&M Institute for Neuroscience, College Station, TX, USA.
- Department of Biology, Texas A&M University, College Station, TX, USA.
| | - Ryan T Massopust
- Texas A&M Institute for Neuroscience, College Station, TX, USA
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Seth G Haddix
- Texas A&M Institute for Neuroscience, College Station, TX, USA
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Young Il Lee
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Wesley J Thompson
- Texas A&M Institute for Neuroscience, College Station, TX, USA
- Department of Biology, Texas A&M University, College Station, TX, USA
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26
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Chan ZCK, Kwan HLR, Wong YS, Jiang Z, Zhou Z, Tam KW, Chan YS, Chan CB, Lee CW. Site-directed MT1-MMP trafficking and surface insertion regulate AChR clustering and remodeling at developing NMJs. eLife 2020; 9:54379. [PMID: 32208136 PMCID: PMC7093154 DOI: 10.7554/elife.54379] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/10/2020] [Indexed: 12/12/2022] Open
Abstract
At vertebrate neuromuscular junctions (NMJs), the synaptic basal lamina contains different extracellular matrix (ECM) proteins and synaptogenic factors that induce and maintain synaptic specializations. Here, we report that podosome-like structures (PLSs) induced by ubiquitous ECM proteins regulate the formation and remodeling of acetylcholine receptor (AChR) clusters via focal ECM degradation. Mechanistically, ECM degradation is mediated by PLS-directed trafficking and surface insertion of membrane-type 1 matrix metalloproteinase (MT1-MMP) to AChR clusters through microtubule-capturing mechanisms. Upon synaptic induction, MT1-MMP plays a crucial role in the recruitment of aneural AChR clusters for the assembly of postsynaptic specializations. Lastly, the structural defects of NMJs in embryonic MT1-MMP-/- mice further demonstrate the physiological role of MT1-MMP in normal NMJ development. Collectively, this study suggests that postsynaptic MT1-MMP serves as a molecular switch to synaptogenesis by modulating local ECM environment for the deposition of synaptogenic signals that regulate postsynaptic differentiation at developing NMJs.
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Affiliation(s)
- Zora Chui-Kuen Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Hiu-Lam Rachel Kwan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Yin Shun Wong
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong, China
| | - Zhixin Jiang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Zhongjun Zhou
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Kin Wai Tam
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Ying-Shing Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Chi Bun Chan
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong, China
| | - Chi Wai Lee
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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27
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Pęziński M, Daszczuk P, Pradhan BS, Lochmüller H, Prószyński TJ. An improved method for culturing myotubes on laminins for the robust clustering of postsynaptic machinery. Sci Rep 2020; 10:4524. [PMID: 32161296 PMCID: PMC7066178 DOI: 10.1038/s41598-020-61347-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 02/20/2020] [Indexed: 01/03/2023] Open
Abstract
Motor neurons form specialized synapses with skeletal muscle fibers, called neuromuscular junctions (NMJs). Cultured myotubes are used as a simplified in vitro system to study the postsynaptic specialization of muscles. The stimulation of myotubes with the glycoprotein agrin or laminin-111 induces the clustering of postsynaptic machinery that contains acetylcholine receptors (AChRs). When myotubes are grown on laminin-coated surfaces, AChR clusters undergo developmental remodeling to form topologically complex structures that resemble mature NMJs. Needing further exploration are the molecular processes that govern AChR cluster assembly and its developmental maturation. Here, we describe an improved protocol for culturing muscle cells to promote the formation of complex AChR clusters. We screened various laminin isoforms and showed that laminin-221 was the most potent for inducing AChR clusters, whereas laminin-121, laminin-211, and laminin-221 afforded the highest percentages of topologically complex assemblies. Human primary myotubes that were formed by myoblasts obtained from patient biopsies also assembled AChR clusters that underwent remodeling in vitro. Collectively, these results demonstrate an advancement of culturing myotubes that can facilitate high-throughput screening for potential therapeutic targets for neuromuscular disorders.
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Affiliation(s)
- Marcin Pęziński
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Patrycja Daszczuk
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Bhola Shankar Pradhan
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.,Łukasiewicz Research Network - PORT Polish Center for Technology Development, Wrocław, Poland
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Centre, University of Freiburg, Freiburg, Germany.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| | - Tomasz J Prószyński
- Laboratory of Synaptogenesis, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland. .,Łukasiewicz Research Network - PORT Polish Center for Technology Development, Wrocław, Poland.
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28
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The role of the dystrophin glycoprotein complex on the neuromuscular system. Neurosci Lett 2020; 722:134833. [DOI: 10.1016/j.neulet.2020.134833] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/07/2020] [Accepted: 02/09/2020] [Indexed: 12/26/2022]
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29
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MMP-mediated modulation of ECM environment during axonal growth and NMJ development. Neurosci Lett 2020; 724:134822. [PMID: 32061716 DOI: 10.1016/j.neulet.2020.134822] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 01/31/2020] [Accepted: 02/04/2020] [Indexed: 12/19/2022]
Abstract
Motor neurons, skeletal muscles, and perisynaptic Schwann cells interact with extracellular matrix (ECM) to form the tetrapartite synapse in the peripheral nervous system. Dynamic remodeling of ECM composition is essential to diversify its functions for distinct cellular processes during neuromuscular junction (NMJ) development. In this review, we give an overview of the proteolytic regulation of ECM proteins, particularly by secreted and membrane-type matrix metalloproteinases (MMPs), in axonal growth and NMJ development. It is suggested that MMP-2, MMP-9, and membrane type 1-MMP (MT1-MMP) promote axonal outgrowth and regeneration upon injury by clearing the glial scars at the lesion site. In addition, these MMPs also play roles in neuromuscular synaptogenesis, ranging from spontaneous formation of synaptic specializations to activity-dependent synaptic elimination, via proteolytic cleavage or degradation of growth factors, neurotrophic factors, and ECM molecules. For instance, secreted MMP-3 has been known to cleave agrin, the main postsynaptic differentiation inducer, further highlighting the importance of MMPs in NMJ formation and maintenance. Furthermore, the increased level of several MMPs in myasthenia gravis (MG) patient suggest the pathophysiological mechanisms of MMP-mediated proteolytic degradation in MG pathogenesis. Finally, we speculate on potential major future directions for studying the regulatory functions of MMP-mediated ECM remodeling in axonal growth and NMJ development.
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30
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Li L, Yokoyama H, Kaburagi H, Hirai T, Tsuji K, Enomoto M, Wakabayashi Y, Okawa A. Remnant neuromuscular junctions in denervated muscles contribute to functional recovery in delayed peripheral nerve repair. Neural Regen Res 2020; 15:731-738. [PMID: 31638098 PMCID: PMC6975147 DOI: 10.4103/1673-5374.266925] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Schwann cell proliferation in peripheral nerve injury (PNI) enhances axonal regeneration compared to central nerve injury. However, even in PNI, long-term nerve damage without repair induces degeneration of neuromuscular junctions (NMJs), and muscle atrophy results in irreversible dysfunction. The peripheral regeneration of motor axons depends on the duration of skeletal muscle denervation. To overcome this difficulty in nerve regeneration, detailed mechanisms should be determined for not only Schwann cells but also NMJ degeneration after PNI and regeneration after nerve repair. Here, we examined motor axon denervation in the tibialis anterior muscle after peroneal nerve transection in thy1-YFP mice and regeneration with nerve reconstruction using allografts. The number of NMJs in the tibialis anterior muscle was maintained up to 4 weeks and then decreased at 6 weeks after injury. In contrast, the number of Schwann cells showed a stepwise decline and then reached a plateau at 6 weeks after injury. For regeneration, we reconstructed the degenerated nerve with an allograft at 4 and 6 weeks after injury, and evaluated functional and histological outcomes for 10 to 12 weeks after grafting. A higher number of pretzel-shaped NMJs in the tibialis anterior muscle and better functional recovery were observed in mice with a 4-week delay in surgery than in those with a 6-week delay. Nerve repair within 4 weeks after PNI is necessary for successful recovery in mice. Prevention of synaptic acetylcholine receptor degeneration may play a key role in peripheral nerve regeneration. All animal experiments were approved by the Institutional Animal Care and Use Committee of Tokyo Medical and Dental University on 5 July 2017, 30 March 2018, and 15 May 2019 (A2017-311C, A2018-297A, and A2019-248A), respectively.
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Affiliation(s)
- Leyang Li
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroyuki Yokoyama
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hidetoshi Kaburagi
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takashi Hirai
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kunikazu Tsuji
- Department of Cartilage Regeneration, Tokyo Medical and Dental University, Tokyo, Japan
| | - Mitsuhiro Enomoto
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoshiaki Wakabayashi
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Atsushi Okawa
- Department of Orthopedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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31
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Swenarchuk LE. Nerve, Muscle, and Synaptogenesis. Cells 2019; 8:cells8111448. [PMID: 31744142 PMCID: PMC6912269 DOI: 10.3390/cells8111448] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/21/2022] Open
Abstract
The vertebrate skeletal neuromuscular junction (NMJ) has long served as a model system for studying synapse structure, function, and development. Over the last several decades, a neuron-specific isoform of agrin, a heparan sulfate proteoglycan, has been identified as playing a central role in synapse formation at all vertebrate skeletal neuromuscular synapses. While agrin was initially postulated to be the inductive molecule that initiates synaptogenesis, this model has been modified in response to work showing that postsynaptic differentiation can develop in the absence of innervation, and that synapses can form in transgenic mice in which the agrin gene is ablated. In place of a unitary mechanism for neuromuscular synapse formation, studies in both mice and zebrafish have led to the proposal that two mechanisms mediate synaptogenesis, with some synapses being induced by nerve contact while others involve the incorporation of prepatterned postsynaptic structures. Moreover, the current model also proposes that agrin can serve two functions, to induce synaptogenesis and to stabilize new synapses, once these are formed. This review examines the evidence for these propositions, and concludes that it remains possible that a single molecular mechanism mediates synaptogenesis at all NMJs, and that agrin acts as a stabilizer, while its role as inducer is open to question. Moreover, if agrin does not act to initiate synaptogenesis, it follows that as yet uncharacterized molecular interactions are required to play this essential inductive role. Several alternatives to agrin for this function are suggested, including focal pericellular proteolysis and integrin signaling, but all require experimental validation.
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Pérez V, Bermedo-Garcia F, Zelada D, Court FA, Pérez MÁ, Fuenzalida M, Ábrigo J, Cabello-Verrugio C, Moya-Alvarado G, Tapia JC, Valenzuela V, Hetz C, Bronfman FC, Henríquez JP. The p75 NTR neurotrophin receptor is required to organize the mature neuromuscular synapse by regulating synaptic vesicle availability. Acta Neuropathol Commun 2019; 7:147. [PMID: 31514753 PMCID: PMC6739937 DOI: 10.1186/s40478-019-0802-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/01/2019] [Indexed: 02/07/2023] Open
Abstract
The coordinated movement of organisms relies on efficient nerve-muscle communication at the neuromuscular junction. After peripheral nerve injury or neurodegeneration, motor neurons and Schwann cells increase the expression of the p75NTR pan-neurotrophin receptor. Even though p75NTR targeting has emerged as a promising therapeutic strategy to delay peripheral neuronal damage progression, the effects of long-term p75NTR inhibition at the mature neuromuscular junction have not been elucidated. We performed quantitative neuroanathomical analyses of the neuromuscular junction in p75NTR null mice by laser confocal and electron microscopy, which were complemented with electromyography, locomotor tests, and pharmacological intervention studies. Mature neuromuscular synapses of p75NTR null mice show impaired postsynaptic organization and ultrastructural complexity, which correlate with altered synaptic function at the levels of nerve activity-induced muscle responses, muscle fiber structure, force production, and locomotor performance. Our results on primary myotubes and denervated muscles indicate that muscle-derived p75NTR does not play a major role on postsynaptic organization. In turn, motor axon terminals of p75NTR null mice display a strong reduction in the number of synaptic vesicles and active zones. According to the observed pre and postsynaptic defects, pharmacological acetylcholinesterase inhibition rescued nerve-dependent muscle response and force production in p75NTR null mice. Our findings revealing that p75NTR is required to organize mature neuromuscular junctions contribute to a comprehensive view of the possible effects caused by therapeutic attempts to target p75NTR.
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Affiliation(s)
- Viviana Pérez
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Center for Advanced Microscopy (CMA BioBio), Universidad de Concepción, Concepción, Chile
| | - Francisca Bermedo-Garcia
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Center for Advanced Microscopy (CMA BioBio), Universidad de Concepción, Concepción, Chile
| | - Diego Zelada
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Center for Advanced Microscopy (CMA BioBio), Universidad de Concepción, Concepción, Chile
| | - Felipe A Court
- Center for Integrative Biology, Faculty of Sciences, Universidad Mayor; FONDAP Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
| | - Miguel Ángel Pérez
- Laboratory of Neural Plasticity, Center for Neurobiology and Integrative Physiology, Faculty of Sciences, Institute of Physiology, Universidad de Valparaíso, Valparaíso, Chile
- Present Address: Health Sciences School, Universidad de Viña del Mar, Viña del Mar, Chile
| | - Marco Fuenzalida
- Laboratory of Neural Plasticity, Center for Neurobiology and Integrative Physiology, Faculty of Sciences, Institute of Physiology, Universidad de Valparaíso, Valparaíso, Chile
| | - Johanna Ábrigo
- Laboratory of Muscle Pathologies, Fragility and Aging, Department of Biological Sciences, Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andrés Bello, Santiago, Chile
| | - Claudio Cabello-Verrugio
- Laboratory of Muscle Pathologies, Fragility and Aging, Department of Biological Sciences, Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andrés Bello, Santiago, Chile
| | - Guillermo Moya-Alvarado
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Carlos Tapia
- Department of Biomedical Sciences, Faculty of Health Sciences, Universidad de Talca, Talca, Chile
| | - Vicente Valenzuela
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Francisca C Bronfman
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
- Center for Aging and Regeneration (CARE), Institute of Biomedical Sciences (ICB), Faculty of Medicine and Faculty of Life Sciences, Universidad Andrés Bello, Santiago, Chile.
| | - Juan Pablo Henríquez
- Neuromuscular Studies Laboratory (NeSt Lab), Department of Cell Biology, Center for Advanced Microscopy (CMA BioBio), Universidad de Concepción, Concepción, Chile.
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Epperson HE, Sandage MJ. Neuromuscular Development in Neonates and Postnatal Infants: Implications for Neuromuscular Electrical Stimulation Therapy for Dysphagia. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2019; 62:2575-2583. [PMID: 31343903 DOI: 10.1044/2019_jslhr-s-18-0502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Purpose The aim of the current study was to review neuromuscular development, summarize the current body of evidence describing the use of neuromuscular electrical stimulation (NMES) therapy in infants, and identify possible contraindications for the use of NMES in the neonate and young infant. Method After a review of the literature describing neuromuscular development, we created a timeline of the developmental processes. Key milestones were determined, and a literature search was conducted to identify potential effects of electrical stimulation on this process. Results Current evidence supporting the use of NMES in the pediatric population is limited and of poor quality. Contraindications of the use of NMES in the neonate and young infant were identified, including (a) inhibited expression of the neural cell adhesion molecule that is vital for neuromuscular development, (b) alteration of muscle fiber type metabolic profile away from intended muscle fiber type morphology, and (c) interruption of postsynaptic acetylcholine receptor synthesis during neuromuscular junction development. Conclusion The use of NMES for the treatment of dysphagia in the neonate and young infant may influence early neuromuscular development in a manner that is not currently well understood. Future research is needed to further understand the effects of NMES on the developing neuromuscular system.
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Affiliation(s)
| | - Mary J Sandage
- Department of Communication Disorders, Auburn University, AL
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Koppel N, Friese MB, Cardasis HL, Neubert TA, Burden SJ. Vezatin is required for the maturation of the neuromuscular synapse. Mol Biol Cell 2019; 30:2571-2583. [PMID: 31411944 PMCID: PMC6740198 DOI: 10.1091/mbc.e19-06-0313] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Key genes, such as Agrin, Lrp4, and MuSK, are required for the initial formation, subsequent maturation, and long-term stabilization of mammalian neuromuscular synapses. Additional molecules are thought to function selectively during the evolution and stabilization of these synapses, but these molecular players are largely unknown. Here, we used mass spectrometry to identify vezatin, a two-pass transmembrane protein, as an acetylcholine receptor (AChR)–associated protein, and we provide evidence that vezatin binds directly to AChRs. We show that vezatin is dispensable for the formation of synapses but plays a later role in the emergence of a topologically complex and branched shape of the synapse, as well as the stabilization of AChRs. In addition, neuromuscular synapses in vezatin mutant mice display premature signs of deterioration, normally found only during aging. Thus, vezatin has a selective role in the structural elaboration and postnatal maturation of murine neuromuscular synapses.
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Affiliation(s)
- Natasha Koppel
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Matthew B Friese
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Helene L Cardasis
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Thomas A Neubert
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
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35
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Mella J, Pérez V, Zelada D, Moreno N, Ionescu A, Perlson E, Henríquez JP. Efficient gene transfer into primary muscle cells to analyze nerve-independent postsynaptic organization in vitro. Neuromuscul Disord 2019; 29:533-542. [DOI: 10.1016/j.nmd.2019.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/23/2019] [Accepted: 05/17/2019] [Indexed: 01/08/2023]
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Lee YI. Differences in the constituent fiber types contribute to the intermuscular variation in the timing of the developmental synapse elimination. Sci Rep 2019; 9:8694. [PMID: 31213646 PMCID: PMC6582271 DOI: 10.1038/s41598-019-45090-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 05/28/2019] [Indexed: 11/09/2022] Open
Abstract
The emergence of a mature nervous system requires a significant refinement of the synaptic connections initially formed during development. Redundant synaptic connections are removed in a process known as synapse elimination. Synapse elimination has been extensively studied at the rodent neuromuscular junction (NMJ). Although several axons initially converge onto each postsynaptic muscle fiber, all redundant inputs are removed during early postnatal development until a single motor neuron innervates each NMJ. Neuronal activity as well as synaptic glia influence the course of synapse elimination. It is, however, unclear whether target muscle fibers are more than naïve substrates in this process. I examined the influence of target myofiber contractile properties on synapse elimination. The timing of redundant input removal in muscles examined correlates strongly with their proportion of slow myofibers: muscles with more slow fibers undergo elimination more slowly. Moreover, this intermuscular difference in the timing of synapse elimination appears to result from local differences in the rate of elimination on fast versus slow myofibers. These results, therefore, imply that differences in the constituent fiber types help account for the variation in the timing of the developmental synapse elimination between muscles and show that the muscle plays a role in the process.
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Affiliation(s)
- Young Il Lee
- Department of Biology, Texas A&M University, College Station, TX, 77843, Texas, USA.
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Slater CR. 'Fragmentation' of NMJs: a sign of degeneration or regeneration? A long journey with many junctions. Neuroscience 2019; 439:28-40. [PMID: 31129203 DOI: 10.1016/j.neuroscience.2019.05.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/07/2019] [Accepted: 05/07/2019] [Indexed: 12/13/2022]
Abstract
Mammalian neuromuscular junctions (NMJs) often consist of curved bands of synaptic contact, about 3-6 μm wide, which resemble pretzels. This contrasts with the NMJs of most animal species which consist of a cluster of separate synaptic spots, each of which is also about 3-6 μm across. In a number of situations, including a variety of disease states as well as normal ageing, mammalian NMJs acquire a more 'fragmented' appearance that resembles somewhat that of other species. This 'fragmentation' of the NMJ has sometimes been interpreted as a 'disintegration' or 'degeneration', with the suggestion that it might be associated with impaired neuromuscular transmission. An alternative view is that NMJ fragmentation is the outcome of a normal process by which the NMJ is maintained in an effective state. In this highly personal commentary, I cite a number of examples of this and point out that although the 'pretzel' form arises during normal development as a result of the sculpting of an immature synaptic 'plaque', in virtually all situations where new synaptic contact is established in adult mammals this occurs by the addition of new synaptic 'spots' rather than by the extension, or neoformation, of 'pretzels'. Further, where appropriate studies have been performed, no evidence of a correlation between the degree of fragmentation and the efficacy of transmission has emerged. It may therefore be more appropriate to consider NMJ 'fragmentation' as a form of regeneration, rather than of degeneration. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Clarke R Slater
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
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38
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Oury J, Liu Y, Töpf A, Todorovic S, Hoedt E, Preethish-Kumar V, Neubert TA, Lin W, Lochmüller H, Burden SJ. MACF1 links Rapsyn to microtubule- and actin-binding proteins to maintain neuromuscular synapses. J Cell Biol 2019; 218:1686-1705. [PMID: 30842214 PMCID: PMC6504910 DOI: 10.1083/jcb.201810023] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 01/07/2019] [Accepted: 02/07/2019] [Indexed: 12/20/2022] Open
Abstract
Oury et al. show that the scaffolding protein MACF1 links Rapsyn, which binds acetylcholine receptors, to the microtubule- and actin-network at neuromuscular synapses. MACF1 thereby plays a role in synaptic maturation in mice, and mutations of MACF1 are associated with congenital myasthenia in humans. Complex mechanisms are required to form neuromuscular synapses, direct their subsequent maturation, and maintain the synapse throughout life. Transcriptional and post-translational pathways play important roles in synaptic differentiation and direct the accumulation of the neurotransmitter receptors, acetylcholine receptors (AChRs), to the postsynaptic membrane, ensuring for reliable synaptic transmission. Rapsyn, an intracellular peripheral membrane protein that binds AChRs, is essential for synaptic differentiation, but how Rapsyn acts is poorly understood. We screened for proteins that coisolate with AChRs in a Rapsyn-dependent manner and show that microtubule actin cross linking factor 1 (MACF1), a scaffolding protein with binding sites for microtubules (MT) and actin, is concentrated at neuromuscular synapses, where it binds Rapsyn and serves as a synaptic organizer for MT-associated proteins, EB1 and MAP1b, and the actin-associated protein, Vinculin. MACF1 plays an important role in maintaining synaptic differentiation and efficient synaptic transmission in mice, and variants in MACF1 are associated with congenital myasthenia in humans.
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Affiliation(s)
- Julien Oury
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | - Yun Liu
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Slobodanka Todorovic
- Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia and Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Esthelle Hoedt
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | | | - Thomas A Neubert
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | - Weichun Lin
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Centro Nacional de Análisis Genómico, Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
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Saini J, Faroni A, Abd Al Samid M, Reid AJ, Lightfoot AP, Mamchaoui K, Mouly V, Butler-Browne G, McPhee JS, Degens H, Al-Shanti N. Simplified in vitro engineering of neuromuscular junctions between rat embryonic motoneurons and immortalized human skeletal muscle cells. STEM CELLS AND CLONING-ADVANCES AND APPLICATIONS 2019; 12:1-9. [PMID: 30863121 PMCID: PMC6388735 DOI: 10.2147/sccaa.s187655] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Background Neuromuscular junctions (NMJs) consist of the presynaptic cholinergic motoneuron terminals and the corresponding postsynaptic motor endplates on skeletal muscle fibers. At the NMJ the action potential of the neuron leads, via release of acetylcholine, to muscle membrane depolarization that in turn is translated into muscle contraction and physical movement. Despite the fact that substantial NMJ research has been performed, the potential of in vivo NMJ investigations is inadequate and difficult to employ. A simple and reproducible in vitro NMJ model may provide a robust means to study the impact of neurotrophic factors, growth factors, and hormones on NMJ formation, structure, and function. Methods This report characterizes a novel in vitro NMJ model utilizing immortalized human skeletal muscle stem cells seeded on 35 mm glass-bottom dishes, cocultured and innervated with spinal cord explants from rat embryos at ED 13.5. The cocultures were fixed and stained on day 14 for analysis and assessment of NMJ formation and development. Results This unique serum- and trophic factor-free system permits the growth of cholinergic motoneurons, the formation of mature NMJs, and the development of highly differentiated contractile myotubes, which exhibit appropriate configuration of transversal triads, representative of in vivo conditions. Conclusion This coculture system provides a tool to study vital features of NMJ formation, regulation, maintenance, and repair, as well as a model platform to explore neuromuscular diseases and disorders affecting NMJs.
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Affiliation(s)
- Jasdeep Saini
- Musculoskeletal Science & Sports Medicine Research Centre, School of Healthcare Science, Manchester Metropolitan University, Manchester, UK,
| | - Alessandro Faroni
- Blond McIndoe Laboratories, Division of Cell Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.,Department of Plastic Surgery & Burns, University Hospitals of South Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Marwah Abd Al Samid
- Musculoskeletal Science & Sports Medicine Research Centre, School of Healthcare Science, Manchester Metropolitan University, Manchester, UK,
| | - Adam J Reid
- Blond McIndoe Laboratories, Division of Cell Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.,Department of Plastic Surgery & Burns, University Hospitals of South Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Adam P Lightfoot
- Musculoskeletal Science & Sports Medicine Research Centre, School of Healthcare Science, Manchester Metropolitan University, Manchester, UK,
| | - Kamel Mamchaoui
- Center for Research in Myology, Sorbonne Université- INSERM, Paris, France
| | - Vincent Mouly
- Center for Research in Myology, Sorbonne Université- INSERM, Paris, France
| | | | - Jamie S McPhee
- Department of Sport and Exercise Science, Manchester Metropolitan University, Manchester, UK
| | - Hans Degens
- Musculoskeletal Science & Sports Medicine Research Centre, School of Healthcare Science, Manchester Metropolitan University, Manchester, UK, .,Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania.,University of Medicine and Pharmacy of Targu Mures, Targu Mures, Romania
| | - Nasser Al-Shanti
- Musculoskeletal Science & Sports Medicine Research Centre, School of Healthcare Science, Manchester Metropolitan University, Manchester, UK,
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Lewandowska MK, Bogatikov E, Hierlemann AR, Punga AR. Long-Term High-Density Extracellular Recordings Enable Studies of Muscle Cell Physiology. Front Physiol 2018; 9:1424. [PMID: 30356837 PMCID: PMC6190753 DOI: 10.3389/fphys.2018.01424] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/19/2018] [Indexed: 11/29/2022] Open
Abstract
Skeletal (voluntary) muscle is the most abundant tissue in the body, thus making it an important biomedical research subject. Studies of neuromuscular transmission, including disorders of ion channels or receptors in autoimmune or genetic neuromuscular disorders, require high-spatial-resolution measurement techniques and an ability to acquire repeated recordings over time in order to track pharmacological interventions. Preclinical techniques for studying diseases of neuromuscular transmission can be enhanced by physiologic ex vivo models of tissue-tissue and cell-cell interactions. Here, we present a method, which allows tracking the development of primary skeletal muscle cells from myoblasts into mature contracting myotubes over more than 2 months. In contrast to most previous studies, the myotubes did not detach from the surface but instead formed functional networks between the myotubes, whose electrical signals were observed over the entire culturing period. Primary cultures of mouse myoblasts differentiated into contracting myotubes on a chip that contained an array of 26,400 platinum electrodes at a density of 3,265 electrodes per mm2. Our ability to track extracellular action potentials at subcellular resolution enabled study of skeletal muscle development and kinetics, modes of spiking and spatio-temporal relationships between muscles. The developed system in turn enables creation of a novel electrophysiological platform for establishing ex vivo disease models.
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Affiliation(s)
- Marta K Lewandowska
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
| | - Evgenii Bogatikov
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
| | - Andreas R Hierlemann
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Anna Rostedt Punga
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
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41
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Bai Y, Guo D, Sun X, Tang G, Liao T, Peng Y, Xu J, Shi L. Balanced Rac1 activity controls formation and maintenance of neuromuscular acetylcholine receptor clusters. J Cell Sci 2018; 131:jcs.215251. [PMID: 30012833 DOI: 10.1242/jcs.215251] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 07/02/2018] [Indexed: 11/20/2022] Open
Abstract
Rac1, an important Rho GTPase that regulates the actin cytoskeleton, has long been suggested to participate in acetylcholine receptor (AChR) clustering at the postsynaptic neuromuscular junction. However, how Rac1 is regulated and how it influences AChR clusters have remained unexplored. This study shows that breaking the balance of Rac1 regulation, by either increasing or decreasing its activity, led to impaired formation and maintenance of AChR clusters. By manipulating Rac1 activity at different stages of AChR clustering in cultured myotubes, we show that Rac1 activation was required for the initial formation of AChR clusters, but its persistent activation led to AChR destabilization, and uncontrolled hyperactivation of Rac1 even caused excessive myotube fusion. Both AChR dispersal and myotube fusion induced by Rac1 were dependent on its downstream effector Pak1. Two Rac1 GAPs and six Rac1 GEFs were screened and found to be important for normal AChR clustering. This study reveals that, although general Rac1 activity remains at low levels during terminal differentiation of myotubes and AChR cluster maintenance, tightly regulated Rac1 activity controls normal AChR clustering.
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Affiliation(s)
- Yanyang Bai
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China
| | - Daji Guo
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China
| | - Xiaoyu Sun
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China
| | - Genyun Tang
- Department of Medical Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine, Huaihua 418000, Hunan, China
| | - Tailin Liao
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China
| | - Yinghui Peng
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China
| | - Junyu Xu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China
| | - Lei Shi
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China
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43
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Affiliation(s)
- Lei Li
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Wen-Cheng Xiong
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA
| | - Lin Mei
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA
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Fundamental Molecules and Mechanisms for Forming and Maintaining Neuromuscular Synapses. Int J Mol Sci 2018; 19:ijms19020490. [PMID: 29415504 PMCID: PMC5855712 DOI: 10.3390/ijms19020490] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 01/24/2018] [Accepted: 01/29/2018] [Indexed: 02/08/2023] Open
Abstract
The neuromuscular synapse is a relatively large synapse with hundreds of active zones in presynaptic motor nerve terminals and more than ten million acetylcholine receptors (AChRs) in the postsynaptic membrane. The enrichment of proteins in presynaptic and postsynaptic membranes ensures a rapid, robust, and reliable synaptic transmission. Over fifty years ago, classic studies of the neuromuscular synapse led to a comprehensive understanding of how a synapse looks and works, but these landmark studies did not reveal the molecular mechanisms responsible for building and maintaining a synapse. During the past two-dozen years, the critical molecular players, responsible for assembling the specialized postsynaptic membrane and regulating nerve terminal differentiation, have begun to be identified and their mechanism of action better understood. Here, we describe and discuss five of these key molecular players, paying heed to their discovery as well as describing their currently understood mechanisms of action. In addition, we discuss the important gaps that remain to better understand how these proteins act to control synaptic differentiation and maintenance.
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Stockinger J, Maxwell N, Shapiro D, deCabo R, Valdez G. Caloric Restriction Mimetics Slow Aging of Neuromuscular Synapses and Muscle Fibers. J Gerontol A Biol Sci Med Sci 2017; 73:21-28. [PMID: 28329051 DOI: 10.1093/gerona/glx023] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/26/2017] [Indexed: 11/14/2022] Open
Abstract
Resveratrol and metformin have been shown to mimic some aspects of caloric restriction and exercise. However, it remains unknown if these molecules also slow age-related synaptic degeneration, as previously shown for caloric restriction and exercise. In this study, we examined the structural integrity of neuromuscular junctions (NMJs) in 2-year-old mice treated with resveratrol and metformin starting at 1 year of age. We found that resveratrol significantly slows aging of NMJs in the extensor digitorum longus muscle of 2-year-old mice. Resveratrol also preserved the morphology of muscle fibers in old mice. Although metformin slowed the rate of muscle fiber aging, it did not significantly affect aging of NMJs. Based on these findings, we sought to determine if resveratrol directly affects NMJs. For this, we examined postsynaptic sites, the NMJ region located on the muscle peripheral membrane, on cultured myotubes derived from C2C12 cells. We discovered that resveratrol increases the number of postsynaptic sites on myotubes exhibiting a youthful architecture, suggesting that resveratrol directly affects the NMJ. Altogether, we provide compelling evidence indicating that resveratrol slows aging of NMJs and muscle fibers.
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Affiliation(s)
- Jessica Stockinger
- Virginia Tech Carilion Research Institute, Roanoke College, Virginia.,Department of Biology, Roanoke College, Virginia
| | - Nicholas Maxwell
- Virginia Tech Carilion Research Institute, Roanoke College, Virginia
| | - Dillon Shapiro
- Virginia Tech Carilion Research Institute, Roanoke College, Virginia
| | - Rafael deCabo
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, Maryland
| | - Gregorio Valdez
- Virginia Tech Carilion Research Institute, Roanoke College, Virginia.,Department of Biological Sciences, Virginia Tech
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46
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Abstract
Skeletal muscle cells are large syncytia, containing hundreds of nuclei positioned regularly along the length of the fiber. During development, nuclei are actively distributed throughout the myotube by the microtubule motor proteins, kinesin-1, and cytoplasmic dynein. Nuclear movement consists of translocation along the long axis of the cell concurrent with three-dimensional rotation of nuclei. In this chapter we describe methods for quantitatively assessing the speed of nuclear rotation in cultured myotubes using live-cell imaging techniques coupled with rigid body kinematic analyses. Additionally, we provide protocols for analyzing nuclear distribution in myotubes.
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47
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Mis K, Grubic Z, Lorenzon P, Sciancalepore M, Mars T, Pirkmajer S. In Vitro Innervation as an Experimental Model to Study the Expression and Functions of Acetylcholinesterase and Agrin in Human Skeletal Muscle. Molecules 2017; 22:molecules22091418. [PMID: 28846617 PMCID: PMC6151842 DOI: 10.3390/molecules22091418] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/18/2017] [Accepted: 08/23/2017] [Indexed: 12/19/2022] Open
Abstract
Acetylcholinesterase (AChE) and agrin, a heparan-sulfate proteoglycan, reside in the basal lamina of the neuromuscular junction (NMJ) and play key roles in cholinergic transmission and synaptogenesis. Unlike most NMJ components, AChE and agrin are expressed in skeletal muscle and α-motor neurons. AChE and agrin are also expressed in various other types of cells, where they have important alternative functions that are not related to their classical roles in NMJ. In this review, we first focus on co-cultures of embryonic rat spinal cord explants with human skeletal muscle cells as an experimental model to study functional innervation in vitro. We describe how this heterologous rat-human model, which enables experimentation on highly developed contracting human myotubes, offers unique opportunities for AChE and agrin research. We then highlight innovative approaches that were used to address salient questions regarding expression and alternative functions of AChE and agrin in developing human skeletal muscle. Results obtained in co-cultures are compared with those obtained in other models in the context of general advances in the field of AChE and agrin neurobiology.
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Affiliation(s)
- Katarina Mis
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia.
| | - Zoran Grubic
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia.
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, via A. Fleming 22, I-34127 Trieste, Italy.
| | - Marina Sciancalepore
- Department of Life Sciences, University of Trieste, via A. Fleming 22, I-34127 Trieste, Italy.
| | - Tomaz Mars
- Department of Life Sciences, University of Trieste, via A. Fleming 22, I-34127 Trieste, Italy.
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia.
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48
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Bernadzki KM, Gawor M, Pęziński M, Mazurek P, Niewiadomski P, Rędowicz MJ, Prószyński TJ. Liprin-α-1 is a novel component of the murine neuromuscular junction and is involved in the organization of the postsynaptic machinery. Sci Rep 2017; 7:9116. [PMID: 28831123 PMCID: PMC5567263 DOI: 10.1038/s41598-017-09590-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/25/2017] [Indexed: 01/26/2023] Open
Abstract
Neuromuscular junctions (NMJs) are specialized synapses that connect motor neurons to skeletal muscle fibers and orchestrate proper signal transmission from the nervous system to muscles. The efficient formation and maintenance of the postsynaptic machinery that contains acetylcholine receptors (AChR) are indispensable for proper NMJ function. Abnormalities in the organization of synaptic components often cause severe neuromuscular disorders, such as muscular dystrophy. The dystrophin-associated glycoprotein complex (DGC) was shown to play an important role in NMJ development. We recently identified liprin-α-1 as a novel binding partner for one of the cytoplasmic DGC components, α-dystrobrevin-1. In the present study, we performed a detailed analysis of localization and function of liprin-α-1 at the murine NMJ. We showed that liprin-α-1 localizes to both pre- and postsynaptic compartments at the NMJ, and its synaptic enrichment depends on the presence of the nerve. Using cultured muscle cells, we found that liprin-α-1 plays an important role in AChR clustering and the organization of cortical microtubules. Our studies provide novel insights into the function of liprin-α-1 at vertebrate neuromuscular synapses.
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Affiliation(s)
- Krzysztof M Bernadzki
- Laboratory of Synaptogenesis, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland
| | - Marta Gawor
- Laboratory of Synaptogenesis, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland
| | - Marcin Pęziński
- Laboratory of Synaptogenesis, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland
| | - Paula Mazurek
- Laboratory of Synaptogenesis, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland
| | - Paweł Niewiadomski
- Laboratory of Synaptogenesis, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland
| | - Maria J Rędowicz
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland
| | - Tomasz J Prószyński
- Laboratory of Synaptogenesis, Polish Academy of Sciences, 3 Pasteura Street, Warsaw, 02-093, Poland.
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49
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Xenopus Nerve-Muscle Cultures: a Novel Cell-Based Assay for Serological Diagnosis and Pathological Research of Myasthenia Gravis. CURRENT PATHOBIOLOGY REPORTS 2017. [DOI: 10.1007/s40139-017-0126-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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50
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Vezina-Audette R, Tremblay M, Carbonetto S. Laminin is instructive and calmodulin dependent kinase II is non-permissive for the formation of complex aggregates of acetylcholine receptors on myotubes in culture. Matrix Biol 2016; 57-58:106-123. [PMID: 27964993 DOI: 10.1016/j.matbio.2016.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/16/2016] [Indexed: 12/11/2022]
Abstract
Previous work has shown that myotubes cultured on laminin-coated substrates form complex aggregates of synaptic proteins that are similar in shape and composition to neuromuscular junctions (NMJs). Here we show that laminin instructs the location of complex aggregates which form only on the lower surface when laminin is coated onto culture dishes but over the entire cell when laminin is added in solution. Silencing of myotubes by agents that block electrical activity (tetrodotoxin, verapamil) or by inhibitors of calmodulin dependent kinase (CaMKII) render the myotube permissive for the formation of complex aggregates. Treatment with laminin alone will facilitate the formation of complex aggregates hours later when myotubes are made permissive by inhibiting CaMKII. The AChR agonist carbachol disperses pre formed aggregates suggesting that non-permissiveness may involve active dispersal of AChRs. The permissive period requires ongoing protein synthesis. The latter may reflect a requirement for rapsyn, which turns over rapidly, and is necessary for aggregation. Consistent with this geldanamycin, an agent that increases rapsyn turnover disrupts complex aggregates. Agrin is well known to induce small clusters of AChRs but does not induce complex aggregates even though aggregate formation requires MuSK, a receptor tyrosine kinase activated by agrin. Dystroglycan (DG) is the major laminin receptor mediating complex aggregate formation with some contribution from β1 integrins. In addition, there is a pool of CaMKII associated with DG. We discuss how these permissive and instructive mechanisms bear on NMJ formation in vivo.
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Affiliation(s)
- Raphael Vezina-Audette
- Centre for Research in Neuroscience, and Dept. of Neurology, McGill University Health Centre, 1650, Cedar Ave., Montreal, Quebec, H3G 1A4, Canada
| | - Mathieu Tremblay
- Centre for Research in Neuroscience, and Dept. of Neurology, McGill University Health Centre, 1650, Cedar Ave., Montreal, Quebec, H3G 1A4, Canada
| | - Salvatore Carbonetto
- Centre for Research in Neuroscience, and Dept. of Neurology, McGill University Health Centre, 1650, Cedar Ave., Montreal, Quebec, H3G 1A4, Canada.
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