1
|
Nebol A, Gouti M. A new era in neuromuscular junction research: current advances in self-organized and assembled in vitro models. Curr Opin Genet Dev 2024; 87:102229. [PMID: 39047588 DOI: 10.1016/j.gde.2024.102229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/27/2024] [Accepted: 06/30/2024] [Indexed: 07/27/2024]
Abstract
Understanding the development and function of the human neuromuscular system is crucial for deciphering the mechanisms of neuromuscular disorders and developing effective therapies. However, limitations of animal models necessitate the development of human-specific in vitro models to study such complex diseases effectively. Here, we discuss different approaches for in vitro neuromuscular junction (NMJ) modeling: complex self-organized models that rely on the inherent abilities of cells to form NMJs based on embryonic developmental principles and assembled models that depend on integrating different cell types for controlled NMJ formation. Finally, we discuss the advantages and limitations of these models and the need for continued advancements enhanced by bioengineering approaches to deepen our understanding of human NMJ biology and pave the way for personalized medicine.
Collapse
Affiliation(s)
- Aylin Nebol
- Max Delbrück Center, Berlin 13125, Germany. https://twitter.com/@aylinnebol
| | - Mina Gouti
- Max Delbrück Center, Berlin 13125, Germany.
| |
Collapse
|
2
|
Sahota VK, Stone A, Woodling NS, Spiers JG, Steinert JR, Partridge L, Augustin H. Plum modulates Myoglianin and regulates synaptic function in D. melanogaster. Open Biol 2023; 13:230171. [PMID: 37699519 PMCID: PMC10497343 DOI: 10.1098/rsob.230171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023] Open
Abstract
Alterations in the neuromuscular system underlie several neuromuscular diseases and play critical roles in the development of sarcopenia, the age-related loss of muscle mass and function. Mammalian Myostatin (MST) and GDF11, members of the TGF-β superfamily of growth factors, are powerful regulators of muscle size in both model organisms and humans. Myoglianin (MYO), the Drosophila homologue of MST and GDF11, is a strong inhibitor of synaptic function and structure at the neuromuscular junction in flies. Here, we identified Plum, a transmembrane cell surface protein, as a modulator of MYO function in the larval neuromuscular system. Reduction of Plum in the larval body-wall muscles abolishes the previously demonstrated positive effect of attenuated MYO signalling on both muscle size and neuromuscular junction structure and function. In addition, downregulation of Plum on its own results in decreased synaptic strength and body weight, classifying Plum as a (novel) regulator of neuromuscular function and body (muscle) size. These findings offer new insights into possible regulatory mechanisms behind ageing- and disease-related neuromuscular dysfunctions in humans and identify potential targets for therapeutic interventions.
Collapse
Affiliation(s)
- Virender K. Sahota
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Aelfwin Stone
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Nathaniel S. Woodling
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Jereme G. Spiers
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Joern R. Steinert
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Linda Partridge
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
| | - Hrvoje Augustin
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
| |
Collapse
|
3
|
Navarro-Martínez A, Vicente-García C, Carvajal JJ. NMJ-related diseases beyond the congenital myasthenic syndromes. Front Cell Dev Biol 2023; 11:1216726. [PMID: 37601107 PMCID: PMC10436495 DOI: 10.3389/fcell.2023.1216726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/21/2023] [Indexed: 08/22/2023] Open
Abstract
Neuromuscular junctions (NMJs) are a special type of chemical synapse that transmits electrical stimuli from motor neurons (MNs) to their innervating skeletal muscle to induce a motor response. They are an ideal model for the study of synapses, given their manageable size and easy accessibility. Alterations in their morphology or function lead to neuromuscular disorders, such as the congenital myasthenic syndromes, which are caused by mutations in proteins located in the NMJ. In this review, we highlight novel potential candidate genes that may cause or modify NMJs-related pathologies in humans by exploring the phenotypes of hundreds of mouse models available in the literature. We also underscore the fact that NMJs may differ between species, muscles or even sexes. Hence the importance of choosing a good model organism for the study of NMJ-related diseases: only taking into account the specific features of the mammalian NMJ, experimental results would be efficiently translated to the clinic.
Collapse
Affiliation(s)
| | - Cristina Vicente-García
- Centro Andaluz de Biología del Desarrollo, CSIC-UPO-JA, Universidad Pablo de Olavide, Sevilla, Spain
| | | |
Collapse
|
4
|
Bushra S, Lin YN, Joudaki A, Ito M, Ohkawara B, Ohno K, Masuda A. Neural Isoforms of Agrin Are Generated by Reduced PTBP1-RNA Interaction Network Spanning the Neuron-Specific Splicing Regions in AGRN. Int J Mol Sci 2023; 24:ijms24087420. [PMID: 37108583 PMCID: PMC10139058 DOI: 10.3390/ijms24087420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Agrin is a heparan sulfate proteoglycan essential for the clustering of acetylcholine receptors at the neuromuscular junction. Neuron-specific isoforms of agrin are generated by alternative inclusion of three exons, called Y, Z8, and Z11 exons, although their processing mechanisms remain elusive. We found, by inspection of splicing cis-elements into the human AGRN gene, that binding sites for polypyrimidine tract binding protein 1 (PTBP1) were extensively enriched around Y and Z exons. PTBP1-silencing enhanced the coordinated inclusion of Y and Z exons in human SH-SY5Y neuronal cells, even though three constitutive exons are flanked by these alternative exons. Deletion analysis using minigenes identified five PTBP1-binding sites with remarkable splicing repression activities around Y and Z exons. Furthermore, artificial tethering experiments indicated that binding of a single PTBP1 molecule to any of these sites represses nearby Y or Z exons as well as the other distal exons. The RRM4 domain of PTBP1, which is required for looping out a target RNA segment, was likely to play a crucial role in the repression. Neuronal differentiation downregulates PTBP1 expression and promotes the coordinated inclusion of Y and Z exons. We propose that the reduction in the PTPB1-RNA network spanning these alternative exons is essential for the generation of the neuron-specific agrin isoforms.
Collapse
Affiliation(s)
- Samira Bushra
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Ying-Ni Lin
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Atefeh Joudaki
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Mikako Ito
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| |
Collapse
|
5
|
Nikolaou N, Gordon PM, Hamid F, Taylor R, Lloyd-Jones J, Makeyev EV, Houart C. Cytoplasmic pool of U1 spliceosome protein SNRNP70 shapes the axonal transcriptome and regulates motor connectivity. Curr Biol 2022; 32:5099-5115.e8. [PMID: 36384140 DOI: 10.1016/j.cub.2022.10.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 09/09/2022] [Accepted: 10/21/2022] [Indexed: 11/17/2022]
Abstract
Regulation of pre-mRNA splicing and polyadenylation plays a profound role in neurons by diversifying the proteome and modulating gene expression in response to physiological cues. Although most of the pre-mRNA processing is thought to occur in the nucleus, numerous splicing regulators are also found in neurites. Here, we show that U1-70K/SNRNP70, a component of the major spliceosome, localizes in RNA-associated granules in zebrafish axons. We identify the extra-nuclear SNRNP70 as an important regulator of motor axonal growth, nerve-dependent acetylcholine receptor (AChR) clustering, and neuromuscular synaptogenesis. This cytoplasmic pool has a protective role for a limited number of transcripts regulating their abundance and trafficking inside axons. Moreover, non-nuclear SNRNP70 regulates splice variants of transcripts such as agrin, thereby controlling synapse formation. Our results point to an unexpected, yet essential, function of non-nuclear SNRNP70 in axonal development, indicating a role of spliceosome proteins in cytoplasmic RNA metabolism during neuronal connectivity.
Collapse
Affiliation(s)
- Nikolas Nikolaou
- Centre for Developmental Neurobiology MRC CNDD, IoPPN, Guy's Campus, King's College London, London SE1 1UL, UK; Department of Life Sciences, University of Bath, Bath BA2 7AY, UK.
| | - Patricia M Gordon
- Centre for Developmental Neurobiology MRC CNDD, IoPPN, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Fursham Hamid
- Centre for Developmental Neurobiology MRC CNDD, IoPPN, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Richard Taylor
- Centre for Developmental Neurobiology MRC CNDD, IoPPN, Guy's Campus, King's College London, London SE1 1UL, UK
| | | | - Eugene V Makeyev
- Centre for Developmental Neurobiology MRC CNDD, IoPPN, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Corinne Houart
- Centre for Developmental Neurobiology MRC CNDD, IoPPN, Guy's Campus, King's College London, London SE1 1UL, UK.
| |
Collapse
|
6
|
Deconstruction of Neurotrypsin Reveals a Multi-factorially Regulated Activity Affecting Myotube Formation and Neuronal Excitability. Mol Neurobiol 2022; 59:7466-7485. [PMID: 36197591 PMCID: PMC9616769 DOI: 10.1007/s12035-022-03056-2] [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: 06/03/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022]
Abstract
Neurotrypsin (NT) is a highly specific nervous system multi-domain serine protease best known for its selective processing of the potent synaptic organizer agrin. Its enzymatic activity is thought to influence processes of synaptic plasticity, with its deregulation causing accelerated neuromuscular junction (NMJ) degeneration or contributing to forms of mental retardation. These biological effects are likely to stem from NT-based regulation of agrin signaling. However, dissecting the exact biological implications of NT-agrin interplay is difficult, due to the scarce molecular detail regarding NT activity and NT-agrin interactions. We developed a strategy to reliably produce and purify a catalytically competent engineered variant of NT called "NT-mini" and a library of C-terminal agrin fragments, with which we performed a thorough biochemical and biophysical characterization of NT enzyme functionality. We studied the regulatory effects of calcium ions and heparin, identified NT's heparin-binding domain, and discovered how zinc ions induce modulation of enzymatic activity. Additionally, we investigated myotube differentiation and hippocampal neuron excitability, evidencing a dose-dependent increase in neuronal activity alongside a negative impact on myoblast fusion when using the active NT enzyme. Collectively, our results provide in vitro and cellular foundations to unravel the molecular underpinnings and biological significance of NT-agrin interactions.
Collapse
|
7
|
Volpe P, Bosutti A, Nori A, Filadi R, Gherardi G, Trautmann G, Furlan S, Massaria G, Sciancalepore M, Megighian A, Caccin P, Bernareggi A, Salanova M, Sacchetto R, Sandonà D, Pizzo P, Lorenzon P. Nerve-dependent distribution of subsynaptic type 1 inositol 1,4,5-trisphosphate receptor at the neuromuscular junction. J Gen Physiol 2022; 154:213498. [PMID: 36149386 PMCID: PMC9513380 DOI: 10.1085/jgp.202213128] [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: 02/13/2022] [Revised: 08/30/2022] [Accepted: 09/09/2022] [Indexed: 11/20/2022] Open
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are enriched at postsynaptic membrane compartments of the neuromuscular junction (NMJ), surrounding the subsynaptic nuclei and close to nicotinic acetylcholine receptors (nAChRs) of the motor endplate. At the endplate level, it has been proposed that nerve-dependent electrical activity might trigger IP3-associated, local Ca2+ signals not only involved in excitation-transcription (ET) coupling but also crucial to the development and stabilization of the NMJ itself. The present study was undertaken to examine whether denervation affects the subsynaptic IP3R distribution in skeletal muscles and which are the underlying mechanisms. Fluorescence microscopy, carried out on in vivo denervated muscles (following sciatectomy) and in vitro denervated skeletal muscle fibers from flexor digitorum brevis (FDB), indicates that denervation causes a reduction in the subsynaptic IP3R1-stained region, and such a decrease appears to be determined by the lack of muscle electrical activity, as judged by partial reversal upon field electrical stimulation of in vitro denervated skeletal muscle fibers.
Collapse
Affiliation(s)
- Pompeo Volpe
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
- Correspondence to Pompeo Volpe:
| | | | - Alessandra Nori
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
| | - Riccardo Filadi
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
- National Research Council, Neuroscience Institute, Padova, Italy
| | - Gaia Gherardi
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
| | - Gabor Trautmann
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Institute of Integrative Neuroanatomy, Berlin, Germany
| | - Sandra Furlan
- National Research Council, Neuroscience Institute, Padova, Italy
| | | | | | - Aram Megighian
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
| | - Paola Caccin
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
| | | | - Michele Salanova
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Institute of Integrative Neuroanatomy, Berlin, Germany
- Neuromuscular Signaling, Center of Space Medicine Berlin, Berlin, Germany
| | - Roberta Sacchetto
- Department of Comparative Biomedicine and Food Science, University of Padova, Padova, Italy
| | - Dorianna Sandonà
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences and Interdepartmental Research Center of Myology (cirMYO), University of Padova, Padova, Italy
- National Research Council, Neuroscience Institute, Padova, Italy
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, Trieste, Italy
| |
Collapse
|
8
|
Dungan CM, Brightwell CR, Wen Y, Zdunek CJ, Latham CM, Thomas NT, Zagzoog AM, Brightwell BD, Nolt GL, Keeble AR, Watowich SJ, Murach KA, Fry CS. Muscle-Specific Cellular and Molecular Adaptations to Late-Life Voluntary Concurrent Exercise. FUNCTION 2022; 3:zqac027. [PMID: 35774589 PMCID: PMC9233305 DOI: 10.1093/function/zqac027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/06/2022] [Accepted: 05/08/2022] [Indexed: 01/07/2023] Open
Abstract
Murine exercise models can provide information on factors that influence muscle adaptability with aging, but few translatable solutions exist. Progressive weighted wheel running (PoWeR) is a simple, voluntary, low-cost, high-volume endurance/resistance exercise approach for training young mice. In the current investigation, aged mice (22-mo-old) underwent a modified version of PoWeR for 8 wk. Muscle functional, cellular, biochemical, transcriptional, and myonuclear DNA methylation analyses provide an encompassing picture of how muscle from aged mice responds to high-volume combined training. Mice run 6-8 km/d, and relative to sedentary mice, PoWeR increases plantarflexor muscle strength. The oxidative soleus of aged mice responds to PoWeR similarly to young mice in every parameter measured in previous work; this includes muscle mass, glycolytic-to-oxidative fiber type transitioning, fiber size, satellite cell frequency, and myonuclear number. The oxidative/glycolytic plantaris adapts according to fiber type, but with modest overall changes in muscle mass. Capillarity increases markedly with PoWeR in both muscles, which may be permissive for adaptability in advanced age. Comparison to published PoWeR RNA-sequencing data in young mice identified conserved regulators of adaptability across age and muscles; this includes Aldh1l1 which associates with muscle vasculature. Agrn and Samd1 gene expression is upregulated after PoWeR simultaneous with a hypomethylated promoter CpG in myonuclear DNA, which could have implications for innervation and capillarization. A promoter CpG in Rbm10 is hypomethylated by late-life exercise in myonuclei, consistent with findings in muscle tissue. PoWeR and the data herein are a resource for uncovering cellular and molecular regulators of muscle adaptation with aging.
Collapse
Affiliation(s)
- Cory M Dungan
- Department of Physical Therapy, University of Kentucky, Lexington 40536, KY, USA
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
| | - Camille R Brightwell
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington 40536, KY, USA
| | - Yuan Wen
- Department of Physical Therapy, University of Kentucky, Lexington 40536, KY, USA
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
| | | | - Christine M Latham
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington 40536, KY, USA
| | - Nicholas T Thomas
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington 40536, KY, USA
| | - Alyaa M Zagzoog
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington 40536, KY, USA
| | - Benjamin D Brightwell
- Kinesiology and Health Promotion Graduate Program, University of Kentucky, Lexington 40536, KY, USA
| | - Georgia L Nolt
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
| | - Alexander R Keeble
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington 40536, KY, USA
| | - Stanley J Watowich
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston 77555, TX, USA
| | - Kevin A Murach
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville 72701, AR, USA
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville 72701, AR, USA
| | - Christopher S Fry
- Center for Muscle Biology, University of Kentucky, Lexington 40536, KY, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington 40536, KY, USA
| |
Collapse
|
9
|
Hörner SJ, Couturier N, Bruch R, Koch P, Hafner M, Rudolf R. hiPSC-Derived Schwann Cells Influence Myogenic Differentiation in Neuromuscular Cocultures. Cells 2021; 10:cells10123292. [PMID: 34943800 PMCID: PMC8699767 DOI: 10.3390/cells10123292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/20/2021] [Accepted: 11/21/2021] [Indexed: 12/13/2022] Open
Abstract
Motoneurons, skeletal muscle fibers, and Schwann cells form synapses, termed neuromuscular junctions (NMJs). These control voluntary body movement and are affected in numerous neuromuscular diseases. Therefore, a variety of NMJ in vitro models have been explored to enable mechanistic and pharmacological studies. So far, selective integration of Schwann cells in these models has been hampered, due to technical limitations. Here we present robust protocols for derivation of Schwann cells from human induced pluripotent stem cells (hiPSC) and their coculture with hiPSC-derived motoneurons and C2C12 muscle cells. Upon differentiation with tuned BMP signaling, Schwann cells expressed marker proteins, S100b, Gap43, vimentin, and myelin protein zero. Furthermore, they displayed typical spindle-shaped morphologies with long processes, which often aligned with motoneuron axons. Inclusion of Schwann cells in coculture experiments with hiPSC-derived motoneurons and C2C12 myoblasts enhanced myotube growth and affected size and number of acetylcholine receptor plaques on myotubes. Altogether, these data argue for the availability of a consistent differentiation protocol for Schwann cells and their amenability for functional integration into neuromuscular in vitro models, fostering future studies of neuromuscular mechanisms and disease.
Collapse
Affiliation(s)
- Sarah Janice Hörner
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, 68163 Mannheim, Germany; (S.J.H.); (N.C.); (R.B.); (M.H.)
- Interdisciplinary Center for Neurosciences, Heidelberg University, 69120 Heidelberg, Germany
| | - Nathalie Couturier
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, 68163 Mannheim, Germany; (S.J.H.); (N.C.); (R.B.); (M.H.)
| | - Roman Bruch
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, 68163 Mannheim, Germany; (S.J.H.); (N.C.); (R.B.); (M.H.)
| | - Philipp Koch
- Central Institute of Mental Health, Medical Faculty Mannheim of Heidelberg University, 68159 Mannheim, Germany;
- Hector Institute for Translational Brain Research (HITBR gGmbH), 68159 Mannheim, Germany
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Mathias Hafner
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, 68163 Mannheim, Germany; (S.J.H.); (N.C.); (R.B.); (M.H.)
- Institute of Medical Technology, Mannheim University of Applied Sciences and Heidelberg University, 68163 Mannheim, Germany
| | - Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, 68163 Mannheim, Germany; (S.J.H.); (N.C.); (R.B.); (M.H.)
- Interdisciplinary Center for Neurosciences, Heidelberg University, 69120 Heidelberg, Germany
- Institute of Medical Technology, Mannheim University of Applied Sciences and Heidelberg University, 68163 Mannheim, Germany
- Correspondence:
| |
Collapse
|
10
|
Li Y, Zhang Y, Hu Q, Egranov SD, Xing Z, Zhang Z, Liang K, Ye Y, Pan Y, Chatterjee SS, Mistretta B, Nguyen TK, Hawke DH, Gunaratne PH, Hung MC, Han L, Yang L, Lin C. Functional significance of gain-of-function H19 lncRNA in skeletal muscle differentiation and anti-obesity effects. Genome Med 2021; 13:137. [PMID: 34454586 PMCID: PMC8403366 DOI: 10.1186/s13073-021-00937-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 07/09/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Exercise training is well established as the most effective way to enhance muscle performance and muscle building. The composition of skeletal muscle fiber type affects systemic energy expenditures, and perturbations in metabolic homeostasis contribute to the onset of obesity and other metabolic dysfunctions. Long noncoding RNAs (lncRNAs) have been demonstrated to play critical roles in diverse cellular processes and diseases, including human cancers; however, the functional importance of lncRNAs in muscle performance, energy balance, and obesity remains elusive. We previously reported that the lncRNA H19 regulates the poly-ubiquitination and protein stability of dystrophin (DMD) in muscular dystrophy. METHODS Here, we identified mouse/human H19-interacting proteins using mouse/human skeletal muscle tissues and liquid chromatography-mass spectrometry (LC-MS). Human induced pluripotent stem-derived skeletal muscle cells (iPSC-SkMC) from a healthy donor and Becker Muscular Dystrophy (BMD) patients were utilized to study DMD post-translational modifications and associated proteins. We identified a gain-of-function (GOF) mutant of H19 and characterized the effects on myoblast differentiation and fusion to myotubes using iPSCs. We then conjugated H19 RNA gain-of-function oligonucleotides (Rgof) with the skeletal muscle enrichment peptide agrin (referred to as AGR-H19-Rgof) and evaluated AGR-H19-Rgof's effects on skeletal muscle performance using wild-type (WT) C57BL/6 J mice and its anti-obesity effects using high-fat diet (HFD)- and leptin deficiency-induced obese mouse models. RESULTS We demonstrated that both human and mouse H19 associated with DMD and that the H19 GOF exhibited enhanced interaction with DMD compared to WT H19. DMD was found to associate with serine/threonine-protein kinase MRCK alpha (MRCKα) and α-synuclein (SNCA) in iPSC-SkMC derived from BMD patients. Inhibition of MRCKα and SNCA-mediated phosphorylation of DMD antagonized the interaction between H19 and DMD. These signaling events led to improved skeletal muscle cell differentiation and myotube fusion. The administration of AGR-H19-Rgof improved the muscle mass, muscle performance, and base metabolic rate of WT mice. Furthermore, mice treated with AGR-H19-Rgof exhibited resistance to HFD- or leptin deficiency-induced obesity. CONCLUSIONS Our study suggested the functional importance of the H19 GOF mutant in enhancing muscle performance and anti-obesity effects.
Collapse
Affiliation(s)
- Yajuan Li
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Yaohua Zhang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Qingsong Hu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Sergey D Egranov
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Zhen Xing
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
- Current address: Sanofi U.S., Boston, MA, 02139, USA
| | - Zhao Zhang
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, 77030, USA
| | - Ke Liang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Youqiong Ye
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, 77030, USA
| | - Yinghong Pan
- Department of Biochemistry and Biology, University of Houston, Houston, TX, 77204, USA
- Current address: UPMC Genome Center, Pittsburgh, PA, 15232, USA
| | - Sujash S Chatterjee
- Department of Biochemistry and Biology, University of Houston, Houston, TX, 77204, USA
| | - Brandon Mistretta
- Department of Biochemistry and Biology, University of Houston, Houston, TX, 77204, USA
| | - Tina K Nguyen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - David H Hawke
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Preethi H Gunaratne
- Department of Biochemistry and Biology, University of Houston, Houston, TX, 77204, USA
| | - Mien-Chie Hung
- Graduate Institute of Biomedical Sciences, Research Center for Cancer Biology, and Center for Molecular Medicine, China Medical University, Taichung, 404, Taiwan
- Department of Biotechnology, Asia University, Taichung, 413, Taiwan
| | - Leng Han
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, 77030, USA
- Center for Epigenetics and Disease Prevention, Institute of Biosciences and Technology, Texas A&M University, Houston, TX, 77030, USA
| | - Liuqing Yang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
- Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
- The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
| | - Chunru Lin
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
- Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
| |
Collapse
|
11
|
Dobrowolny G, Barbiera A, Sica G, Scicchitano BM. Age-Related Alterations at Neuromuscular Junction: Role of Oxidative Stress and Epigenetic Modifications. Cells 2021; 10:1307. [PMID: 34074012 PMCID: PMC8225025 DOI: 10.3390/cells10061307] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/19/2021] [Accepted: 05/22/2021] [Indexed: 12/11/2022] Open
Abstract
With advancing aging, a decline in physical abilities occurs, leading to reduced mobility and loss of independence. Although many factors contribute to the physio-pathological effects of aging, an important event seems to be related to the compromised integrity of the neuromuscular system, which connects the brain and skeletal muscles via motoneurons and the neuromuscular junctions (NMJs). NMJs undergo severe functional, morphological, and molecular alterations during aging and ultimately degenerate. The effect of this decline is an inexorable decrease in skeletal muscle mass and strength, a condition generally known as sarcopenia. Moreover, several studies have highlighted how the age-related alteration of reactive oxygen species (ROS) homeostasis can contribute to changes in the neuromuscular junction morphology and stability, leading to the reduction in fiber number and innervation. Increasing evidence supports the involvement of epigenetic modifications in age-dependent alterations of the NMJ. In particular, DNA methylation, histone modifications, and miRNA-dependent gene expression represent the major epigenetic mechanisms that play a crucial role in NMJ remodeling. It is established that environmental and lifestyle factors, such as physical exercise and nutrition that are susceptible to change during aging, can modulate epigenetic phenomena and attenuate the age-related NMJs changes. This review aims to highlight the recent epigenetic findings related to the NMJ dysregulation during aging and the role of physical activity and nutrition as possible interventions to attenuate or delay the age-related decline in the neuromuscular system.
Collapse
Affiliation(s)
- Gabriella Dobrowolny
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics (DAHFMO)-Unit of Histology and Medical Embryology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, 00161 Rome, Italy;
| | - Alessandra Barbiera
- Department of Life Sciences and Public Health, Histology and Embryology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (A.B.); (G.S.)
| | - Gigliola Sica
- Department of Life Sciences and Public Health, Histology and Embryology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (A.B.); (G.S.)
| | - Bianca Maria Scicchitano
- Department of Life Sciences and Public Health, Histology and Embryology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (A.B.); (G.S.)
| |
Collapse
|
12
|
Fuertes-Alvarez S, Izeta A. Terminal Schwann Cell Aging: Implications for Age-Associated Neuromuscular Dysfunction. Aging Dis 2021; 12:494-514. [PMID: 33815879 PMCID: PMC7990373 DOI: 10.14336/ad.2020.0708] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/08/2020] [Indexed: 12/11/2022] Open
Abstract
Action potential is transmitted to muscle fibers through specialized synaptic interfaces called neuromuscular junctions (NMJs). These structures are capped by terminal Schwann cells (tSCs), which play essential roles during formation and maintenance of the NMJ. tSCs are implicated in the correct communication between nerves and muscles, and in reinnervation upon injury. During aging, loss of muscle mass and strength (sarcopenia and dynapenia) are due, at least in part, to the progressive loss of contacts between muscle fibers and nerves. Despite the important role of tSCs in NMJ function, very little is known on their implication in the NMJ-aging process and in age-associated denervation. This review summarizes the current knowledge about the implication of tSCs in the age-associated degeneration of NMJs. We also speculate on the possible mechanisms underlying the observed phenotypes.
Collapse
Affiliation(s)
- Sandra Fuertes-Alvarez
- 1Biodonostia, Tissue Engineering Group, Paseo Dr. Begiristain, s/n, San Sebastian 20014, Spain
| | - Ander Izeta
- 1Biodonostia, Tissue Engineering Group, Paseo Dr. Begiristain, s/n, San Sebastian 20014, Spain.,2Tecnun-University of Navarra, School of Engineering, Department of Biomedical Engineering and Science, Paseo Mikeletegi, 48, San Sebastian 20009, Spain
| |
Collapse
|
13
|
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: 73] [Impact Index Per Article: 18.3] [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.
Collapse
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
| |
Collapse
|
14
|
Barbeau S, Tahraoui-Bories J, Legay C, Martinat C. Building neuromuscular junctions in vitro. Development 2020; 147:147/22/dev193920. [PMID: 33199350 DOI: 10.1242/dev.193920] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The neuromuscular junction (NMJ) has been the model of choice to understand the principles of communication at chemical synapses. Following groundbreaking experiments carried out over 60 years ago, many studies have focused on the molecular mechanisms underlying the development and physiology of these synapses. This Review summarizes the progress made to date towards obtaining faithful models of NMJs in vitro We provide a historical approach discussing initial experiments investigating NMJ development and function from Xenopus to mice, the creation of chimeric co-cultures, in vivo approaches and co-culture methods from ex vivo and in vitro derived cells, as well as the most recent developments to generate human NMJs. We discuss the benefits of these techniques and the challenges to be addressed in the future for promoting our understanding of development and human disease.
Collapse
Affiliation(s)
- Susie Barbeau
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, F-75006 Paris, France
| | - Julie Tahraoui-Bories
- INSERM/UEPS UMR 861, Paris Saclay Université, I-STEM, 91100 Corbeil-Essonnes, France
| | - Claire Legay
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, F-75006 Paris, France
| | - Cécile Martinat
- INSERM/UEPS UMR 861, Paris Saclay Université, I-STEM, 91100 Corbeil-Essonnes, France
| |
Collapse
|
15
|
Gilbert-Honick J, Iyer SR, Somers SM, Takasuka H, Lovering RM, Wagner KR, Mao HQ, Grayson WL. Engineering 3D skeletal muscle primed for neuromuscular regeneration following volumetric muscle loss. Biomaterials 2020; 255:120154. [PMID: 32562942 PMCID: PMC11192434 DOI: 10.1016/j.biomaterials.2020.120154] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/02/2020] [Accepted: 05/27/2020] [Indexed: 12/14/2022]
Abstract
Volumetric muscle loss (VML) overwhelms the native regenerative capabilities of skeletal muscle and has few effective treatments to regain lost muscle mass and function. Tissue engineered muscle constructs designed to promote neuromuscular regeneration are a promising therapeutic avenue. To date, there has been no engineered muscle construct for VML treatment that has incorporated a pharmacologic agent to promote neuromuscular regeneration. Here, we have modified electrospun fibrin microfiber bundles, which have demonstrated muscle regenerative potential, with the heparan sulfate proteoglycan, agrin, to stimulate innervation post-VML. Myoblasts cultured on microfiber bundles with either soluble or chemically tethered agrin demonstrated statistically significant increased clustering of acetylcholine receptors (AChRs) with soluble agrin displaying AChR clusters throughout the myofiber bundles, and tethered agrin displaying AChR clusters only at 10 μm from the substrate surface. Following implantation into murine VML defects for 4 weeks, constructs pre-treated with soluble or tethered agrin resulted in statistically significant increased neuromuscular junctions, regenerating myofibers, vascular infiltration, neural infiltration, and nuclear yes-associated protein (YAP) expression within the defect site compared to the control without agrin. The agrin-tethered microfiber bundles provided sustained agrin signaling within the regenerating site during the 4-week post-implantation periods and further augmented the density of regenerating myofibers in regenerated tissue with statistical significance compared to constructs with soluble agrin. These data demonstrate the neuromuscular regenerative potential of engineered muscle constructs pre-treated to induce AChR clustering with locally delivered agrin at the site of VML regeneration.
Collapse
Affiliation(s)
- Jordana Gilbert-Honick
- Translational Tissue Engineering Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21231, USA; Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Shama R Iyer
- Department of Orthopedic Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Sarah M Somers
- Translational Tissue Engineering Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21231, USA; Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Hannah Takasuka
- Translational Tissue Engineering Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21231, USA; Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Richard M Lovering
- Department of Orthopedic Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Kathryn R Wagner
- The Hugo W. Moser Research Institute, Kennedy Krieger Institute, Baltimore, MD 21205, USA; Graduate Program in Cellular and Molecular Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Departments of Neurology and Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Hai-Quan Mao
- Translational Tissue Engineering Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21231, USA; Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Materials Science & Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Institute for NanoBioTechnology (INBT), Johns Hopkins University School of Engineering, Baltimore, MD 21218, USA
| | - Warren L Grayson
- Translational Tissue Engineering Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21231, USA; Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Materials Science & Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Institute for NanoBioTechnology (INBT), Johns Hopkins University School of Engineering, Baltimore, MD 21218, USA.
| |
Collapse
|
16
|
Eldridge SE, Barawi A, Wang H, Roelofs AJ, Kaneva M, Guan Z, Lydon H, Thomas BL, Thorup AS, Fernandez BF, Caxaria S, Strachan D, Ali A, Shanmuganathan K, Pitzalis C, Whiteford JR, Henson F, McCaskie AW, De Bari C, Dell'Accio F. Agrin induces long-term osteochondral regeneration by supporting repair morphogenesis. Sci Transl Med 2020; 12:12/559/eaax9086. [PMID: 32878982 DOI: 10.1126/scitranslmed.aax9086] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 04/03/2020] [Accepted: 08/13/2020] [Indexed: 12/11/2022]
Abstract
Cartilage loss leads to osteoarthritis, the most common cause of disability for which there is no cure. Cartilage regeneration, therefore, is a priority in medicine. We report that agrin is a potent chondrogenic factor and that a single intraarticular administration of agrin induced long-lasting regeneration of critical-size osteochondral defects in mice, with restoration of tissue architecture and bone-cartilage interface. Agrin attracted joint resident progenitor cells to the site of injury and, through simultaneous activation of CREB and suppression of canonical WNT signaling downstream of β-catenin, induced expression of the chondrogenic stem cell marker GDF5 and differentiation into stable articular chondrocytes, forming stable articular cartilage. In sheep, an agrin-containing collagen gel resulted in long-lasting regeneration of bone and cartilage, which promoted increased ambulatory activity. Our findings support the therapeutic use of agrin for joint surface regeneration.
Collapse
Affiliation(s)
- Suzanne E Eldridge
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK.
| | - Aida Barawi
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Hui Wang
- Arthritis and Regenerative Medicine Laboratory, Aberdeen Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Anke J Roelofs
- Arthritis and Regenerative Medicine Laboratory, Aberdeen Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Magdalena Kaneva
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Zeyu Guan
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Helen Lydon
- Division of Trauma and Orthopaedic Surgery, Department of Surgery, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK
| | - Bethan L Thomas
- Centre for Biochemical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Anne-Sophie Thorup
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Beatriz F Fernandez
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Sara Caxaria
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Danielle Strachan
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Ahmed Ali
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Kanatheepan Shanmuganathan
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Costantino Pitzalis
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - James R Whiteford
- Comparative Musculoskeletal Biology Group, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Frances Henson
- Centre for Microvascular Research, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Andrew W McCaskie
- Division of Trauma and Orthopaedic Surgery, Department of Surgery, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK
| | - Cosimo De Bari
- Arthritis and Regenerative Medicine Laboratory, Aberdeen Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Francesco Dell'Accio
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK.
| |
Collapse
|
17
|
Belotti E, Schaeffer L. Regulation of Gene expression at the neuromuscular Junction. Neurosci Lett 2020; 735:135163. [PMID: 32553805 DOI: 10.1016/j.neulet.2020.135163] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/11/2020] [Accepted: 06/14/2020] [Indexed: 01/08/2023]
Abstract
Gene expression in skeletal muscle is profoundly changed upon innervation. 50 years of research on the neuromuscular system have greatly increased our understanding of the mechanisms underlying these changes. By controlling the expression and the activity of key transcription factors, nerve-evoked electrical activity in the muscle fiber positively and negatively regulates the expression of hundreds of genes. Innervation also compartmentalizes gene expression into synaptic and extra-synaptic regions of muscle fibers. In addition, electrically-evoked, release of several factors (e.g. Agrin, Neuregulin, Wnt ligands) induce the clustering of synaptic proteins and of a few muscle nuclei. The sub-synaptic nuclei acquire a particular chromatin organization and develop a specific gene expression program dedicated to building and maintaining a functional neuromuscular synapse. Deciphering synapse-specific, transcriptional regulation started with the identification of the N-box, a six base pair element present in the promoters of the acetylcholine δ and ε subunits. Most genes with synapse-specific expression turned out to contain at least one N-box in their promoters. The N-box is a response element for the synaptic signals Agrin and Neuregulins as well as a binding site for transcription factors of the Ets family. The Ets transcription factors GABP and Erm are implicated in the activation of post-synaptic genes via the N-box. In muscle fibers, Erm expression is restricted to the NMJ whereas GABP is expressed in all muscle nuclei but phosphorylated and activated by the JNK and ERK signaling pathways in response to Agrin and Neuregulins. Post-synaptic gene expression also correlates with chromatin modifications at the genomic level as evidenced by the strong enrichment of decondensed chromatin and acetylated histones in sub-synaptic nuclei. Here we discuss these transcriptional pathways for synaptic specialization at NMJs.
Collapse
Affiliation(s)
- Edwige Belotti
- INMG, Inserm U1217, CNRS UMR5310, Université Lyon 1, Université De Lyon, Lyon, France
| | - Laurent Schaeffer
- INMG, Inserm U1217, CNRS UMR5310, Université Lyon 1, Université De Lyon, Lyon, France; Centre De Biotechnologie Cellulaire, Hospices Civils De Lyon, Lyon, France.
| |
Collapse
|
18
|
Guarino SR, Canciani A, Forneris F. Dissecting the Extracellular Complexity of Neuromuscular Junction Organizers. Front Mol Biosci 2020; 6:156. [PMID: 31998752 PMCID: PMC6966886 DOI: 10.3389/fmolb.2019.00156] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 12/13/2019] [Indexed: 12/20/2022] Open
Abstract
Synapse formation is a very elaborate process dependent upon accurate coordination of pre and post-synaptic specialization, requiring multiple steps and a variety of receptors and signaling molecules. Due to its relative structural simplicity and the ease in manipulation and observation, the neuromuscular synapse or neuromuscular junction (NMJ)-the connection between motor neurons and skeletal muscle-represents the archetype junction system for studying synapse formation and conservation. This junction is essential for survival, as it controls our ability to move and breath. NMJ formation requires coordinated interactions between motor neurons and muscle fibers, which ultimately result in the formation of a highly specialized post-synaptic architecture and a highly differentiated nerve terminal. Furthermore, to ensure a fast and reliable synaptic transmission following neurotransmitter release, ligand-gated channels (acetylcholine receptors, AChRs) are clustered on the post-synaptic muscle cell at high concentrations in sites opposite the presynaptic active zone, supporting a direct role for nerves in the organization of the post-synaptic membrane architecture. This organized clustering process, essential for NMJ formation and for life, relies on key signaling molecules and receptors and is regulated by soluble extracellular molecules localized within the synaptic cleft. Notably, several mutations as well as auto-antibodies against components of these signaling complexes have been related to neuromuscular disorders. The recent years have witnessed strong progress in the understanding of molecular identities, architectures, and functions of NMJ macromolecules. Among these, prominent roles have been proposed for neural variants of the proteoglycan agrin, its receptor at NMJs composed of the lipoprotein receptor-related protein 4 (LRP4) and the muscle-specific kinase (MuSK), as well as the regulatory soluble synapse-specific protease Neurotrypsin. In this review we summarize the current state of the art regarding molecular structures and (agrin-dependent) canonical, as well as (agrin-independent) non-canonical, MuSK signaling mechanisms that underscore the formation of neuromuscular junctions, with the aim of providing a broad perspective to further stimulate molecular, cellular and tissue biology investigations on this fundamental intercellular contact.
Collapse
Affiliation(s)
| | | | - Federico Forneris
- The Armenise-Harvard Laboratory of Structural Biology, Department Biology and Biotechnology, University of Pavia, Pavia, Italy
| |
Collapse
|
19
|
Gilbert-Honick J, Grayson W. Vascularized and Innervated Skeletal Muscle Tissue Engineering. Adv Healthc Mater 2020; 9:e1900626. [PMID: 31622051 PMCID: PMC6986325 DOI: 10.1002/adhm.201900626] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/27/2019] [Indexed: 12/12/2022]
Abstract
Volumetric muscle loss (VML) is a devastating loss of muscle tissue that overwhelms the native regenerative properties of skeletal muscle and results in lifelong functional deficits. There are currently no treatments for VML that fully recover the lost muscle tissue and function. Tissue engineering presents a promising solution for VML treatment and significant research has been performed using tissue engineered muscle constructs in preclinical models of VML with a broad range of defect locations and sizes, tissue engineered construct characteristics, and outcome measures. Due to the complex vascular and neural anatomy within skeletal muscle, regeneration of functional vasculature and nerves is vital for muscle recovery following VML injuries. This review aims to summarize the current state of the field of skeletal muscle tissue engineering using 3D constructs for VML treatment with a focus on studies that have promoted vascular and neural regeneration within the muscle tissue post-VML.
Collapse
Affiliation(s)
- Jordana Gilbert-Honick
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Warren Grayson
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Material Sciences & Engineering, Johns Hopkins University, School of Engineering, Baltimore, MD 21218, USA
- Institute for NanoBioTechnology (INBT), Johns Hopkins University School of Engineering, Baltimore, MD 21218, USA
| |
Collapse
|
20
|
Geremek M, Dudarewicz L, Obersztyn E, Paczkowska M, Smyk M, Sobecka K, Nowakowska B. Null variants in AGRN cause lethal fetal akinesia deformation sequence. Clin Genet 2019; 97:634-638. [PMID: 31730230 DOI: 10.1111/cge.13677] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 01/19/2023]
Abstract
We present a case of lethal fetal akinesia deformation sequence (FADS) caused by a frameshift variant in trans with a 148 kbp deletion encompassing 3-36 exons of AGRN. Pathogenic variants in AGRN have been described in families with a form of congenital myasthenic syndrome (CMS), manifesting in the early childhood with variable fatigable muscle weakness. To the best of our knowledge, this is the first case of FADS caused by defects in AGRN gene. FADS has been reported to be caused by pathogenic variants in genes previously associated with CMS including these involved in endplate development and maintenance: MuSK, DOK7, and RAPSN. FADS seems to be the most severe form of CMS. None of the reported in the literature CMS cases associated with AGRN had two null variants, like the case presented herein. This indicates a strong genotype-phenotype correlation.
Collapse
Affiliation(s)
- Maciej Geremek
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
| | - Lech Dudarewicz
- Department of Medical Genetics, Polish Mother's Memorial Hospital, Łódź, Poland
| | - Ewa Obersztyn
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
| | | | - Marta Smyk
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
| | - Katarzyna Sobecka
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
| | - Beata Nowakowska
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
| |
Collapse
|
21
|
Handara G, Kröger S. Alternative Splicing and the Intracellular Domain Mediate TM-agrin's Ability to Differentially Regulate the Density of Excitatory and Inhibitory Synapse-like Specializations in Developing CNS Neurons. Neuroscience 2019; 419:60-71. [PMID: 31672640 DOI: 10.1016/j.neuroscience.2019.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 01/26/2023]
Abstract
Agrin is a multi-domain protein best known for its essential function during formation of the neuromuscular junction. Alternative mRNA splicing at sites named y and z in the C-terminal part of agrin regulates its interaction with a receptor complex consisting of the agrin-binding low-density lipoprotein receptor-related protein 4 (Lrp4) and the muscle-specific kinase (MuSK). Isoforms with inserts at both splice sites bind to Lrp4, activate MuSK and are synaptogenic at the neuromuscular junction. Agrin is also expressed as a transmembrane protein in the central nervous system (CNS) but its function during interneuronal synapse formation is unclear. Recently we demonstrated that transfection of a full-length cDNA coding for transmembrane agrin (TM-agrin) in cultured embryonic cortical neurons induced an Lrp4-dependent but MuSK-independent increase in dendritic glutamatergic synapses and an Lrp4- and MuSK-independent reduction of inhibitory synapses. Here we show that presynaptic specializations were similarly affected by TM-agrin overexpression. In addition, we mapped the regions within TM-agrin responsible for TM-agrin's effects on dendritic aggregates of synapse-associated proteins. We show that the presence of a four amino acid insert at splice site y is essential for the increase in the density of puncta containing the postsynaptic density protein 95 kDa. This effect was independent of splice site z. The reduction of the gephyrin puncta density was independent of the entire extracellular part of TM-agrin but required a highly conserved serine residue in the intracellular domain of TM-agrin. These results provide further evidence for a function of TM-agrin during CNS synaptogenesis and demonstrate that different domains and alternative splicing of TM-agrin differentially affect excitatory and inhibitory synapse formation in cultured embryonic CNS neurons.
Collapse
Affiliation(s)
- Gerry Handara
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152 Planegg-Martinsried, Germany; Institute for Stem Cell Research, German Research Center for Environmental Health, Helmholtz Centre Munich, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Stephan Kröger
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152 Planegg-Martinsried, Germany.
| |
Collapse
|
22
|
Rudell JB, Maselli RA, Yarov-Yarovoy V, Ferns MJ. Pathogenic effects of agrin V1727F mutation are isoform specific and decrease its expression and affinity for HSPGs and LRP4. Hum Mol Genet 2019; 28:2648-2658. [PMID: 30994901 PMCID: PMC6687949 DOI: 10.1093/hmg/ddz081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/27/2019] [Accepted: 04/15/2019] [Indexed: 12/17/2022] Open
Abstract
Agrin is a large extracellular matrix protein whose isoforms differ in their tissue distribution and function. Motoneuron-derived y+z+ agrin regulates the formation of the neuromuscular junction (NMJ), while y-z- agrin is widely expressed and has diverse functions. Previously we identified a missense mutation (V1727F) in the second laminin globular (LG2) domain of agrin that causes severe congenital myasthenic syndrome. Here, we define pathogenic effects of the agrin V1727F mutation that account for the profound dysfunction of the NMJ. First, by expressing agrin variants in heterologous cells, we show that the V1727F mutation reduces the secretion of y+z+ agrin compared to wild type, whereas it has no effect on the secretion of y-z- agrin. Second, we find that the V1727F mutation significantly impairs binding of y+z+ agrin to both heparin and the low-density lipoprotein receptor-related protein 4 (LRP4) coreceptor. Third, molecular modeling of the LG2 domain suggests that the V1727F mutation primarily disrupts the y splice insert, and consistent with this we find that it partially occludes the contribution of the y splice insert to agrin binding to heparin and LRP4. Together, these findings identify several pathogenic effects of the V1727F mutation that reduce its expression and ability to bind heparan sulfate proteoglycan and LRP4 coreceptors involved in the muscle-specific kinase signaling pathway. These defects primarily impair the function of neural y+z+ agrin and combine to cause a severe CMS phenotype, whereas y-z- agrin function in other tissues appears preserved.
Collapse
Affiliation(s)
- John B Rudell
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Ricardo A Maselli
- Department of Neurology, University of California Davis, Davis, CA, USA
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Michael J Ferns
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
- Department of Anesthesiology and Pain Medicine, University of California Davis, Davis, CA, USA
| |
Collapse
|
23
|
Huang ML, Tota EM, Lucas TM, Godula K. Influencing Early Stages of Neuromuscular Junction Formation through Glycocalyx Engineering. ACS Chem Neurosci 2018; 9:3086-3093. [PMID: 30095249 PMCID: PMC6395550 DOI: 10.1021/acschemneuro.8b00295] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Achieving molecular control over the formation of synaptic contacts in the nervous system can provide important insights into their regulation and can offer means for creating well-defined in vitro systems to evaluate modes of therapeutic intervention. Agrin-induced clustering of acetylcholine receptors (AChRs) at postsynaptic sites is a hallmark of the formation of the neuromuscular junction, a synapse between motoneurons and muscle cells. In addition to the cognate agrin receptor LRP4 (low-density lipoprotein receptor related protein-4), muscle cell heparan sulfate (HS) glycosaminoglycans (GAGs) have also been proposed to contribute to AChR clustering by acting as agrin co-receptors. Here, we provide direct evidence for the role of HS GAGs in agrin recruitment to the surface of myotubes, as well as their functional contributions toward AChR clustering. We also demonstrate that engineering of the myotube glycocalyx using synthetic HS GAG polymers can replace native HS structures to gain control over agrin-mediated AChR clustering.
Collapse
Affiliation(s)
| | - Ember M. Tota
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Taryn M. Lucas
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Kamil Godula
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| |
Collapse
|
24
|
Clausen L, Cossins J, Beeson D. Beta-2 Adrenergic Receptor Agonists Enhance AChR Clustering in C2C12 Myotubes: Implications for Therapy of Myasthenic Disorders. J Neuromuscul Dis 2018; 5:231-240. [PMID: 29865088 PMCID: PMC6004912 DOI: 10.3233/jnd-170293] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background: Congenital myasthenic syndromes (CMS) are a group of inherited neuromuscular transmission disorders causing fatiguable muscle weakness. ADRB2 agonists have been observed to provide therapeutic benefit where destabilisation of NMJ structures is part of the underlying pathology, such as in DOK7, COLQ and MuSK CMS as well as in slow channel syndrome. However, very little is known about the molecular mechanisms underlying the effects of ADRB2 agonists in CMS. Objective: In vitro investigation into whether an ADRB2 agonist affects the AChR clustering pathway and has the potential to increase the number and stability of AChR clusters. Methods: Cultured C2C12 mouse myotubes overexpressing the common DOK7 frameshift mutation c.1124_1127dupTGCC were incubated with salbutamol sulphate and the effect on AChR cluster numbers were investigated. Moreover, agrin-induced AChR clusters in C2C12 WT cells were left to disperse after agrin-wash-off, and the effects of incubation with salbutamol sulphate on AChR cluster numbers were explored. Results: Salbutamol sulphate induced a significant increase in the number of AChR clusters formed on C2C12 cells overexpressing c.1124_1127dupTGCC. Furthermore, significantly more clusters remained in C2C12 WT myotubes incubated with salbutamol sulphate following agrin wash-off. Conclusions: The results suggest that ADRB2 agonists directly affect proteins located at the neuromuscular junction and exert a stabilising effect on AChR clusters.
Collapse
Affiliation(s)
- Lisa Clausen
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| |
Collapse
|
25
|
Enhanced skeletal muscle formation on microfluidic spun gelatin methacryloyl (GelMA) fibres using surface patterning and agrin treatment. J Tissue Eng Regen Med 2018; 12:2151-2163. [DOI: 10.1002/term.2738] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 03/19/2018] [Accepted: 07/17/2018] [Indexed: 12/16/2022]
|
26
|
Soliman E, Bianchi F, Sleigh JN, George JH, Cader MZ, Cui Z, Ye H. Engineered method for directional growth of muscle sheets on electrospun fibers. J Biomed Mater Res A 2018; 106:1165-1176. [PMID: 29266766 DOI: 10.1002/jbm.a.36312] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 11/22/2017] [Accepted: 12/15/2017] [Indexed: 12/11/2022]
Abstract
Research on the neuromuscular junction (NMJ) and its function and development spans over a century. However, researchers are limited in their ability to conduct experimentation on this highly specialized synapse between motor neurons and muscle fibers, as NMJs are not easily accessible outside the body. The aim of this work is to provide a reliable and reproducible muscle sheet model for in vitro NMJ study. A novel culture system was designed by engineering a method for the directional growth of myofiber sheets, using muscle progenitor cells cultured on electrospun fiber networks. Myoblastic C2C12 cells cultured on suspended aligned fibers were found to maintain directionality, with alignment angle standard deviations approximately two-thirds lower on fibers than on regular culture surfaces. Morphological studies found nuclei and cytoskeleton aspect ratios to be elongated by 20 and 150%, respectively. Furthermore, neurons were shown to form innervation patterns parallel to suspended fibers when co-cultured on developed muscle sheets, with alignment angle standard deviations three times lower compared with those on typical surfaces. The effect of agrin on samples was quantified through the slow release of agrin medium, encapsulated in alginate pellets and imbedded within culture chambers. Samples exposed to agrin showed significantly increased percentage of AChR-covered area. The developed model has potential to serve as the basis for synaptogenesis and NMJ studies, providing a novel approach to bio-artificial muscle alignment and setting the groundwork for further investigations in innervation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1165-1176, 2018.
Collapse
Affiliation(s)
- Erfan Soliman
- Department of Engineering Sciences, Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - Fabio Bianchi
- Department of Engineering Sciences, Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - James N Sleigh
- Nuffield Department of Clinical Neurosciences, The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital/Headley Way, Oxford, OX3 9DS, United Kingdom
| | - Julian H George
- Department of Engineering Sciences, Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - M Zameel Cader
- Nuffield Department of Clinical Neurosciences, The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital/Headley Way, Oxford, OX3 9DS, United Kingdom
| | - Zhanfeng Cui
- Department of Engineering Sciences, Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - Hua Ye
- Department of Engineering Sciences, Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| |
Collapse
|
27
|
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.
Collapse
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.
| |
Collapse
|
28
|
Yano M, Minegishi Y, Sugita S, Ota N. Milk fat globule membrane supplementation with voluntary running exercise attenuates age-related motor dysfunction by suppressing neuromuscular junction abnormalities in mice. Exp Gerontol 2017; 97:29-37. [PMID: 28729214 DOI: 10.1016/j.exger.2017.07.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 07/05/2017] [Accepted: 07/17/2017] [Indexed: 11/28/2022]
Abstract
Age-related loss of skeletal muscle mass and function attenuates physical performance, and maintaining fine muscle innervation is known to play an important role in its prevention. We had previously shown that consumption of milk fat globule membrane (MFGM) with habitual exercise improves the muscle mass and motor function in humans and mice. Improvement of neuromuscular junction (NMJ) was suggested as one of the mechanisms underlying these effects. In this study, we evaluated the effect of MFGM intake combined with voluntary running (MFGM-VR) on morphological changes of NMJ and motor function in aging mice. Seven months following the intervention, the MFGM-VR group showed a significantly improved motor coordination in the rotarod test and muscle force in the grip strength test compared with the control group at 13 and 14months of age, respectively. In 14-month old control mice, the extensor digitorum longus muscle showed increased abnormal NMJs, such as fragmentation and denervation, compared with 6-month old young mice. However, such age-related deteriorations of NMJs were significantly suppressed in the MFGM-VR group. Increase in the expression of NMJ formation-related genes, such as agrin and LDL Receptor Related Protein 4 (LRP4), might contribute to this beneficial effect. Rotarod performance and grip strength showed significant negative correlation with the status of denervation and fragmentation of NMJs. These results suggest that MFGM intake with voluntary running exercise effectively suppresses age-related morphological deterioration of NMJ, thus contributing to improvement of motor function.
Collapse
Affiliation(s)
- Michiko Yano
- Biological Science Research, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi 321-3497, Japan
| | - Yoshihiko Minegishi
- Biological Science Research, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi 321-3497, Japan
| | - Satoshi Sugita
- Biological Science Research, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi 321-3497, Japan
| | - Noriyasu Ota
- Biological Science Research, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi 321-3497, Japan.
| |
Collapse
|
29
|
Dietary supplementation with bovine-derived milk fat globule membrane lipids promotes neuromuscular development in growing rats. Nutr Metab (Lond) 2017; 14:9. [PMID: 28127382 PMCID: PMC5259894 DOI: 10.1186/s12986-017-0161-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 01/15/2017] [Indexed: 12/11/2022] Open
Abstract
Background The milk fat globule membrane (MFGM) is primarily composed of polar phospho- and sphingolipids, which have established biological effects on neuroplasticity. The present study aimed to investigate the effect of dietary MFGM supplementation on the neuromuscular system during post-natal development. Methods Growing rats received dietary supplementation with bovine-derived MFGM mixtures consisting of complex milk lipids (CML), beta serum concentrate (BSC) or a complex milk lipid concentrate (CMLc) (which lacks MFGM proteins) from post-natal day 10 to day 70. Results Supplementation with MFGM mixtures enriched in polar lipids (BSC and CMLc, but not CML) increased the plasma phosphatidylcholine (PC) concentration, with no effect on plasma phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylserine (PS) or sphingomyelin (SM). In contrast, muscle PC was reduced in rats receiving supplementation with both BSC and CMLc, whereas muscle PI, PE, PS and SM remained unchanged. Rats receiving BSC and CMLc (but not CML) displayed a slow-to-fast muscle fibre type profile shift (MyHCI → MyHCIIa) that was associated with elevated expression of genes involved in myogenic differentiation (myogenic regulatory factors) and relatively fast fibre type specialisation (Myh2 and Nfatc4). Expression of neuromuscular development genes, including nerve cell markers, components of the synaptogenic agrin–LRP4 pathway and acetylcholine receptor subunits, was also increased in muscle of rats supplemented with BSC and CMLc (but not CML). Conclusions These findings demonstrate that dietary supplementation with bovine-derived MFGM mixtures enriched in polar lipids can promote neuromuscular development during post-natal growth in rats, leading to shifts in adult muscle phenotype. Electronic supplementary material The online version of this article (doi:10.1186/s12986-017-0161-y) contains supplementary material, which is available to authorized users.
Collapse
|
30
|
Koneczny I, Stevens JAA, De Rosa A, Huda S, Huijbers MG, Saxena A, Maestri M, Lazaridis K, Zisimopoulou P, Tzartos S, Verschuuren J, van der Maarel SM, van Damme P, De Baets MH, Molenaar PC, Vincent A, Ricciardi R, Martinez-Martinez P, Losen M. IgG4 autoantibodies against muscle-specific kinase undergo Fab-arm exchange in myasthenia gravis patients. J Autoimmun 2016; 77:104-115. [PMID: 27965060 DOI: 10.1016/j.jaut.2016.11.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/17/2016] [Accepted: 11/22/2016] [Indexed: 01/13/2023]
Abstract
Autoimmunity mediated by IgG4 subclass autoantibodies is an expanding field of research. Due to their structural characteristics a key feature of IgG4 antibodies is the ability to exchange Fab-arms with other, unrelated, IgG4 molecules, making the IgG4 molecule potentially monovalent for the specific antigen. However, whether those disease-associated antigen-specific IgG4 are mono- or divalent for their antigens is unknown. Myasthenia gravis (MG) with antibodies to muscle specific kinase (MuSK-MG) is a well-recognized disease in which the predominant pathogenic IgG4 antibody binds to extracellular epitopes on MuSK at the neuromuscular junction; this inhibits a pathway that clusters the acetylcholine (neurotransmitter) receptors and leads to failure of neuromuscular transmission. In vitro Fab-arm exchange-inducing conditions were applied to MuSK antibodies in sera, purified IgG4 and IgG1-3 sub-fractions. Solid-phase cross-linking assays were established to determine the extent of pre-existing and inducible Fab-arm exchange. Functional effects of the resulting populations of IgG4 antibodies were determined by measuring inhibition of agrin-induced AChR clustering in C2C12 cells. To confirm the results, κ/κ, λ/λ and hybrid κ/λ IgG4s were isolated and tested for MuSK antibodies. At least fifty percent of patients had IgG4, but not IgG1-3, MuSK antibodies that could undergo Fab-arm exchange in vitro under reducing conditions. Also MuSK antibodies were found in vivo that were divalent (monospecific for MuSK). Fab-arm exchange with normal human IgG4 did not prevent the inhibitory effect of serum derived MuSK antibodies on AChR clustering in C2C12 mouse myotubes. The results suggest that a considerable proportion of MuSK IgG4 could already be Fab-arm exchanged in vivo. This was confirmed by isolating endogenous IgG4 MuSK antibodies containing both κ and λ light chains, i.e. hybrid IgG4 molecules. These new findings demonstrate that Fab-arm exchanged antibodies are pathogenic.
Collapse
Affiliation(s)
- Inga Koneczny
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Jo A A Stevens
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Anna De Rosa
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Paradisa 2, 56124 Pisa, Italy
| | - Saif Huda
- Neurology Department, Nuffield Department of Clinical Neurosciences, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Maartje G Huijbers
- Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands; Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Abhishek Saxena
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Michelangelo Maestri
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Paradisa 2, 56124 Pisa, Italy
| | - Konstantinos Lazaridis
- Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue 115 21, Ampelokipi, Athens, Greece; Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium
| | - Paraskevi Zisimopoulou
- Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue 115 21, Ampelokipi, Athens, Greece; Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium
| | - Socrates Tzartos
- Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue 115 21, Ampelokipi, Athens, Greece; Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium
| | - Jan Verschuuren
- Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Silvère M van der Maarel
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Philip van Damme
- Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium; KU Leuven - University of Leuven, Department of Neurosciences, VIB - Vesalius Research Center, Experimental Neurology - Laboratory of Neurobiology, Leuven, Belgium
| | - Marc H De Baets
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Peter C Molenaar
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Angela Vincent
- Neurology Department, Nuffield Department of Clinical Neurosciences, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Roberta Ricciardi
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Paradisa 2, 56124 Pisa, Italy
| | - Pilar Martinez-Martinez
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands.
| | - Mario Losen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands.
| |
Collapse
|
31
|
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.
Collapse
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.
| |
Collapse
|
32
|
Li L, Cao Y, Wu H, Ye X, Zhu Z, Xing G, Shen C, Barik A, Zhang B, Xie X, Zhi W, Gan L, Su H, Xiong WC, Mei L. Enzymatic Activity of the Scaffold Protein Rapsyn for Synapse Formation. Neuron 2016; 92:1007-1019. [PMID: 27839998 DOI: 10.1016/j.neuron.2016.10.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 07/21/2016] [Accepted: 10/07/2016] [Indexed: 12/22/2022]
Abstract
Neurotransmission is ensured by a high concentration of neurotransmitter receptors at the postsynaptic membrane. This is mediated by scaffold proteins that bridge the receptors with cytoskeleton. One such protein is rapsyn (receptor-associated protein at synapse), which is essential for acetylcholine receptor (AChR) clustering and NMJ (neuromuscular junction) formation. We show that the RING domain of rapsyn contains E3 ligase activity. Mutation of the RING domain that abolishes the enzyme activity inhibits rapsyn- as well as agrin-induced AChR clustering in heterologous and muscle cells. Further biological and genetic studies support a working model where rapsyn, a classic scaffold protein, serves as an E3 ligase to induce AChR clustering and NMJ formation, possibly by regulation of AChR neddylation. This study identifies a previously unappreciated enzymatic function of rapsyn and a role of neddylation in synapse formation, and reveals a potential target of therapeutic intervention for relevant neurological disorders.
Collapse
Affiliation(s)
- Lei Li
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Yu Cao
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Haitao Wu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Xinchun Ye
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Zhihui Zhu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Guanglin Xing
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Chengyong Shen
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Arnab Barik
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Bin Zhang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Xiaoling Xie
- Department of Ophthalmology, University of Rochester, Rochester, NY 14642, USA
| | - Wenbo Zhi
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Lin Gan
- Department of Ophthalmology, University of Rochester, Rochester, NY 14642, USA
| | - Huabo Su
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Wen-Cheng Xiong
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA; Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA; Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Lin Mei
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA; Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA; Charlie Norwood VA Medical Center, Augusta, GA 30912, USA.
| |
Collapse
|
33
|
Scherbakov N, Knops M, Ebner N, Valentova M, Sandek A, Grittner U, Dahinden P, Hettwer S, Schefold JC, von Haehling S, Anker SD, Joebges M, Doehner W. Evaluation of C-terminal Agrin Fragment as a marker of muscle wasting in patients after acute stroke during early rehabilitation. J Cachexia Sarcopenia Muscle 2016; 7:60-7. [PMID: 27066319 PMCID: PMC4799857 DOI: 10.1002/jcsm.12068] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 07/15/2015] [Accepted: 07/31/2015] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND C-terminal Agrin Fragment (CAF) has been proposed as a novel biomarker for sarcopenia originating from the degeneration of the neuromuscular junctions. In patients with stroke muscle wasting is a common observation that predicts functional outcome. We aimed to evaluate agrin sub-fragment CAF22 as a marker of decreased muscle mass and physical performance in the early phase after acute stroke. METHODS Patients with acute ischaemic or haemorrhagic stroke (n = 123, mean age 70 ± 11 y, body mass index BMI 27.0 ± 4.9 kg/m(2)) admitted to inpatient rehabilitation were studied in comparison to 26 healthy controls of similar age and BMI. Functional assessments were performed at begin (23 ± 17 days post stroke) and at the end of the structured rehabilitation programme (49 ± 18 days post stroke) that included physical assessment, maximum hand grip strength, Rivermead motor assessment, and Barthel index. Body composition was assessed by bioelectrical impedance analysis (BIA). Serum levels of CAF22 were measured by ELISA. RESULTS CAF22 levels were elevated in stroke patients at admission (134.3 ± 52.3 pM) and showed incomplete recovery until discharge (118.2 ± 42.7 pM) compared to healthy controls (95.7 ± 31.8 pM, p < 0.001). Simple regression analyses revealed an association between CAF22 levels and parameters of physical performance, hand grip strength, and phase angle, a BIA derived measure of the muscle cellular integrity. Improvement of the handgrip strength of the paretic arm during rehabilitation was independently related to the recovery of CAF22 serum levels only in those patients who showed increased lean mass during the rehabilitation. CONCLUSIONS CAF22 serum profiles showed a dynamic elevation and recovery in the subacute phase after acute stroke. Further studies are needed to explore the potential of CAF22 as a serum marker to monitor the muscle status in patients after stroke.
Collapse
Affiliation(s)
- Nadja Scherbakov
- Center for Stroke Research CSB Charite Universitätsmedizin Berlin Germany; German Centre for Cardiovascular Research (DZHK), partner site Berlin Germany
| | - Michael Knops
- Center for Stroke Research CSB Charite Universitätsmedizin Berlin Germany
| | - Nicole Ebner
- Innovative Clinical Trials, Department of Cardiology and Pneumology University Medicine Göttingen Germany
| | - Miroslava Valentova
- Innovative Clinical Trials, Department of Cardiology and Pneumology University Medicine Göttingen Germany; 1st Department of Internal Medicine Comenius University Bratislava Slovak Republic
| | - Anja Sandek
- Innovative Clinical Trials, Department of Cardiology and Pneumology University Medicine Göttingen Germany
| | - Ulrike Grittner
- Center for Stroke Research CSB Charite Universitätsmedizin Berlin Germany
| | | | | | - Jörg C Schefold
- Department of Intensive Care Medicine Inselspital, University Hospital of Bern Switzerland
| | - Stephan von Haehling
- Innovative Clinical Trials, Department of Cardiology and Pneumology University Medicine Göttingen Germany
| | - Stefan D Anker
- Innovative Clinical Trials, Department of Cardiology and Pneumology University Medicine Göttingen Germany
| | | | - Wolfram Doehner
- Center for Stroke Research CSB Charite Universitätsmedizin Berlin Germany; German Centre for Cardiovascular Research (DZHK), partner site Berlin Germany; Department of Cardiology Charite Universitätsmedizin Berlin Germany
| |
Collapse
|
34
|
The Basement Membrane Proteoglycans Perlecan and Agrin: Something Old, Something New. CURRENT TOPICS IN MEMBRANES 2015; 76:255-303. [PMID: 26610917 DOI: 10.1016/bs.ctm.2015.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Several members of the proteoglycan family are integral components of basement membranes; other proteoglycan family members interact with or bind to molecular residents of the basement membrane. Proteoglycans are polyfunctional molecules, for they derive their inherent bioactivity from the amino acid motifs embedded in the core protein structure as well as the glycosaminoglycan (GAG) chains that are covalently attached to the core protein. The presence of the covalently attached GAG chains significantly expands the "partnering" potential of proteoglycans, permitting them to interact with a broad spectrum of targets, including growth factors, cytokines, chemokines, and morphogens. Thus proteoglycans in the basement membrane are poised to exert diverse effects on the cells intimately associated with basement membranes.
Collapse
|
35
|
Eldridge S, Nalesso G, Ismail H, Vicente-Greco K, Kabouridis P, Ramachandran M, Niemeier A, Herz J, Pitzalis C, Perretti M, Dell'Accio F. Agrin mediates chondrocyte homeostasis and requires both LRP4 and α-dystroglycan to enhance cartilage formation in vitro and in vivo. Ann Rheum Dis 2015; 75:1228-35. [PMID: 26290588 PMCID: PMC4760904 DOI: 10.1136/annrheumdis-2015-207316] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 07/14/2015] [Indexed: 12/31/2022]
Abstract
Objectives Osteoarthritis (OA) is a leading cause of disability for which there is no cure. The identification of molecules supporting cartilage homeostasis and regeneration is therefore a major pursuit in musculoskeletal medicine. Agrin is a heparan sulfate proteoglycan which, through binding to low-density lipoprotein receptor-related protein 4 (LRP4), is required for neuromuscular synapse formation. In other tissues, it connects the cytoskeleton to the basement membrane through binding to α-dystroglycan. Prompted by an unexpected expression pattern, we investigated the role and receptor usage of agrin in cartilage. Methods Agrin expression pattern was investigated in human osteoarthritic cartilage and following destabilisation of the medial meniscus in mice. Extracellular matrix (ECM) formation and chondrocyte differentiation was studied in gain and loss of function experiments in vitro in three-dimensional cultures and gain of function in vivo, using an ectopic cartilage formation assay in nude mice. Receptor usage was investigated by disrupting LRP4 and α-dystroglycan by siRNA and blocking antibodies respectively. Results Agrin was detected in normal cartilage but was progressively lost in OA. In vitro, agrin knockdown resulted in reduced glycosaminoglycan content, downregulation of the cartilage transcription factor SOX9 and other cartilage-specific ECM molecules. Conversely, exogenous agrin supported cartilage differentiation in vitro and ectopic cartilage formation in vivo. In the context of cartilage differentiation, agrin used an unusual receptor repertoire requiring both LRP4 and α-dystroglycan. Conclusions We have discovered that agrin strongly promotes chondrocyte differentiation and cartilage formation in vivo. Our results identify agrin as a novel potent anabolic growth factor with strong therapeutic potential in cartilage regeneration.
Collapse
Affiliation(s)
- Suzanne Eldridge
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Giovanna Nalesso
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Habib Ismail
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | | | - Panos Kabouridis
- The Francis Crick Institute (Mill Hill Laboratory), The Ridgeway, London, UK
| | - Manoj Ramachandran
- Department of Trauma and Orthopaedic Surgery, Royal London Hospital, London, UK
| | - Andreas Niemeier
- Department of Orthopaedics and IBMII: Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Joachim Herz
- Department of Molecular Genetics, Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Costantino Pitzalis
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Mauro Perretti
- Centre for Biochemical Pharmacology, William Harvey Research Institute, London, UK
| | - Francesco Dell'Accio
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| |
Collapse
|
36
|
Tintignac LA, Brenner HR, Rüegg MA. Mechanisms Regulating Neuromuscular Junction Development and Function and Causes of Muscle Wasting. Physiol Rev 2015; 95:809-52. [DOI: 10.1152/physrev.00033.2014] [Citation(s) in RCA: 224] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The neuromuscular junction is the chemical synapse between motor neurons and skeletal muscle fibers. It is designed to reliably convert the action potential from the presynaptic motor neuron into the contraction of the postsynaptic muscle fiber. Diseases that affect the neuromuscular junction may cause failure of this conversion and result in loss of ambulation and respiration. The loss of motor input also causes muscle wasting as muscle mass is constantly adapted to contractile needs by the balancing of protein synthesis and protein degradation. Finally, neuromuscular activity and muscle mass have a major impact on metabolic properties of the organisms. This review discusses the mechanisms involved in the development and maintenance of the neuromuscular junction, the consequences of and the mechanisms involved in its dysfunction, and its role in maintaining muscle mass during aging. As life expectancy is increasing, loss of muscle mass during aging, called sarcopenia, has emerged as a field of high medical need. Interestingly, aging is also accompanied by structural changes at the neuromuscular junction, suggesting that the mechanisms involved in neuromuscular junction maintenance might be disturbed during aging. In addition, there is now evidence that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia.
Collapse
Affiliation(s)
- Lionel A. Tintignac
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| | - Hans-Rudolf Brenner
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| | - Markus A. Rüegg
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| |
Collapse
|
37
|
Neufeld K, Ezell K, Grow WA. Plastic Additives Decrease Agrin-Induced Acetylcholine Receptor Clusters and Myotube Formation in C2C12 Skeletal Muscle Cell Culture. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/cellbio.2015.41002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
38
|
Tan-Sindhunata MB, Mathijssen IB, Smit M, Baas F, de Vries JI, van der Voorn JP, Kluijt I, Hagen MA, Blom EW, Sistermans E, Meijers-Heijboer H, Waisfisz Q, Weiss MM, Groffen AJ. Identification of a Dutch founder mutation in MUSK causing fetal akinesia deformation sequence. Eur J Hum Genet 2014; 23:1151-7. [PMID: 25537362 PMCID: PMC4538208 DOI: 10.1038/ejhg.2014.273] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/29/2014] [Accepted: 11/10/2014] [Indexed: 01/11/2023] Open
Abstract
Fetal akinesia deformation sequence (FADS) refers to a clinically and genetically heterogeneous group of disorders with congenital malformations related to impaired fetal movement. FADS can result from mutations in CHRNG, CHRNA1, CHRND, DOK7 and RAPSN; however, these genes only account for a minority of cases. Here we identify MUSK as a novel cause of lethal FADS. Fourteen affected fetuses from a Dutch genetic isolate were traced back to common ancestors 11 generations ago. Homozygosity mapping in two fetuses revealed MUSK as a candidate gene. All tested cases carried an identical homozygous variant c.1724T>C; p.(Ile575Thr) in the intracellular domain of MUSK. The carrier frequency in the genetic isolate was 8%, exclusively found in heterozygous carriers. Consistent with the established role of MUSK as a tyrosine kinase that orchestrates neuromuscular synaptogenesis, the fetal myopathy was accompanied by impaired acetylcholine receptor clustering and reduced tyrosine kinase activity at motor nerve endings. A functional assay in myocytes derived from human fetuses confirmed that the variant blocks MUSK-dependent motor endplate formation. Taken together, the results strongly support a causal role of this founder mutation in MUSK, further expanding the gene set associated with FADS and offering new opportunities for prenatal genetic testing.
Collapse
Affiliation(s)
| | - Inge B Mathijssen
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
| | - Margriet Smit
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - Frank Baas
- Department of Genome Analysis, Academic Medical Center, Amsterdam, The Netherlands
| | - Johanna I de Vries
- Department of Obstetrics and Gynaecology, Research Institute MOVE, VU University Medical Center, Amsterdam, The Netherlands
| | | | - Irma Kluijt
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
| | - Marleen A Hagen
- Department of Obstetrics and Gynaecology, Research Institute MOVE, VU University Medical Center, Amsterdam, The Netherlands
| | - Eveline W Blom
- Department of Clinical Genetics, MUMC, Maastricht, The Netherlands
| | - Erik Sistermans
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - Hanne Meijers-Heijboer
- 1] Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands [2] Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
| | - Quinten Waisfisz
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - Marjan M Weiss
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - Alexander J Groffen
- 1] Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands [2] Department of Functional Genomics, Center for Neurogenomics and Cognition Research, VU University, Amsterdam, The Netherlands
| |
Collapse
|
39
|
Mihailovska E, Raith M, Valencia RG, Fischer I, Al Banchaabouchi M, Herbst R, Wiche G. Neuromuscular synapse integrity requires linkage of acetylcholine receptors to postsynaptic intermediate filament networks via rapsyn-plectin 1f complexes. Mol Biol Cell 2014; 25:4130-49. [PMID: 25318670 PMCID: PMC4263455 DOI: 10.1091/mbc.e14-06-1174] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
P1f, a specific isoform of the cytolinker protein plectin, bridges AChRs to the desmin IF network of myofibers via direct interaction with the AChR-scaffolding protein rapsyn. P1f-mediated IF linkage is crucial for the formation and maintenance of AChR clusters, postsynaptic organization of the NMJ, and body locomotion. Mutations in the cytolinker protein plectin lead to grossly distorted morphology of neuromuscular junctions (NMJs) in patients suffering from epidermolysis bullosa simplex (EBS)-muscular dystrophy (MS) with myasthenic syndrome (MyS). Here we investigated whether plectin contributes to the structural integrity of NMJs by linking them to the postsynaptic intermediate filament (IF) network. Live imaging of acetylcholine receptors (AChRs) in cultured myotubes differentiated ex vivo from immortalized plectin-deficient myoblasts revealed them to be highly mobile and unable to coalesce into stable clusters, in contrast to wild-type cells. We found plectin isoform 1f (P1f) to bridge AChRs and IFs via direct interaction with the AChR-scaffolding protein rapsyn in an isoform-specific manner; forced expression of P1f in plectin-deficient cells rescued both compromised AChR clustering and IF network anchoring. In conditional plectin knockout mice with gene disruption in muscle precursor/satellite cells (Pax7-Cre/cKO), uncoupling of AChRs from IFs was shown to lead to loss of postsynaptic membrane infoldings and disorganization of the NMJ microenvironment, including its invasion by microtubules. In their phenotypic behavior, mutant mice closely mimicked EBS-MD-MyS patients, including impaired body balance, severe muscle weakness, and reduced life span. Our study demonstrates that linkage to desmin IF networks via plectin is crucial for formation and maintenance of AChR clusters, postsynaptic NMJ organization, and body locomotion.
Collapse
Affiliation(s)
- Eva Mihailovska
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Marianne Raith
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Rocio G Valencia
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Irmgard Fischer
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Mumna Al Banchaabouchi
- Preclinical Phenotyping Facility, Campus Science Support Facilities, 1030 Vienna, Austria
| | - Ruth Herbst
- Center for Brain Research and Institute of Immunology, Medical University of Vienna, 1030 Vienna, Austria
| | - Gerhard Wiche
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| |
Collapse
|
40
|
Darabid H, Perez-Gonzalez AP, Robitaille R. Neuromuscular synaptogenesis: coordinating partners with multiple functions. Nat Rev Neurosci 2014; 15:630-1. [DOI: 10.1038/nrn3821] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
41
|
Zhang B, Shen C, Bealmear B, Ragheb S, Xiong WC, Lewis RA, Lisak RP, Mei L. Autoantibodies to agrin in myasthenia gravis patients. PLoS One 2014; 9:e91816. [PMID: 24632822 PMCID: PMC3954737 DOI: 10.1371/journal.pone.0091816] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 02/02/2014] [Indexed: 11/19/2022] Open
Abstract
To determine if patients with myasthenia gravis (MG) have antibodies to agrin, a proteoglycan released by motor neurons and is critical for neuromuscular junction (NMJ) formation, we collected serum samples from 93 patients with MG with known status of antibodies to acetylcholine receptor (AChR), muscle specific kinase (MuSK) and lipoprotein-related 4 (LRP4) and samples from control subjects (healthy individuals and individuals with other diseases). Sera were assayed for antibodies to agrin. We found antibodies to agrin in 7 serum samples of MG patients. None of the 25 healthy controls and none of the 55 control neurological patients had agrin antibodies. Two of the four triple negative MG patients (i.e., no detectable AChR, MuSK or LRP4 antibodies, AChR-/MuSK-/LRP4-) had antibodies against agrin. In addition, agrin antibodies were detected in 5 out of 83 AChR+/MuSK-/LRP4- patients but were not found in the 6 patients with MuSK antibodies (AChR-/MuSK+/LRP4-). Sera from MG patients with agrin antibodies were able to recognize recombinant agrin in conditioned media and in transfected HEK293 cells. These sera also inhibited the agrin-induced MuSK phosphorylation and AChR clustering in muscle cells. Together, these observations indicate that agrin is another autoantigen in patients with MG and agrin autoantibodies may be pathogenic through inhibition of agrin/LRP4/MuSK signaling at the NMJ.
Collapse
Affiliation(s)
- Bin Zhang
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Physiology, Basic Medical School, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, Hubei Province, P. R. China
| | - Chengyong Shen
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Beverly Bealmear
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Samia Ragheb
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- Department of Biomedical Sciences, Oakland University William Beaumont School of Medicine, Rochester, Michigan, United States of America
| | - Wen-Cheng Xiong
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Richard A. Lewis
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- Department of Neurology, Cedars-Sinai Medical Center, West Hollywood, California, United States of America
| | - Robert P. Lisak
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- Department of Immunology and Microbiology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Lin Mei
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
- * E-mail:
| |
Collapse
|
42
|
Koneczny I, Cossins J, Waters P, Beeson D, Vincent A. MuSK myasthenia gravis IgG4 disrupts the interaction of LRP4 with MuSK but both IgG4 and IgG1-3 can disperse preformed agrin-independent AChR clusters. PLoS One 2013; 8:e80695. [PMID: 24244707 PMCID: PMC3820634 DOI: 10.1371/journal.pone.0080695] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/13/2013] [Indexed: 12/24/2022] Open
Abstract
A variable proportion of patients with generalized myasthenia gravis (MG) have autoantibodies to muscle specific tyrosine kinase (MuSK). During development agrin, released from the motor nerve, interacts with low density lipoprotein receptor-related protein-4 (LRP4), which then binds to MuSK; MuSK interaction with the intracellular protein Dok7 results in clustering of the acetylcholine receptors (AChRs) on the postsynaptic membrane. In mature muscle, MuSK helps maintain the high density of AChRs at the neuromuscular junction. MuSK antibodies are mainly IgG4 subclass, which does not activate complement and can be monovalent, thus it is not clear how the antibodies cause disruption of AChR numbers or function to cause MG. We hypothesised that MuSK antibodies either reduce surface MuSK expression and/or inhibit the interaction with LRP4. We prepared MuSK IgG, monovalent Fab fragments, IgG1-3 and IgG4 fractions from MuSK-MG plasmas. We asked whether the antibodies caused endocytosis of MuSK in MuSK-transfected cells or if they inhibited binding of LRP4 to MuSK in co-immunoprecipitation experiments. In parallel, we investigated their ability to reduce AChR clusters in C2C12 myotubes induced by a) agrin, reflecting neuromuscular development, and b) by Dok7- overexpression, producing AChR clusters that more closely resemble the adult neuromuscular synapse. Total IgG, IgG4 or IgG1-3 MuSK antibodies were not endocytosed unless cross-linked by divalent anti-human IgG. MuSK IgG, Fab fragments and IgG4 inhibited the binding of LRP4 to MuSK and reduced agrin-induced AChR clustering in C2C12 cells. By contrast, IgG1-3 antibodies did not inhibit LRP4-MuSK binding but, surprisingly, did inhibit agrin-induced clustering. Moreover, both IgG4 and IgG1-3 preparations dispersed agrin-independent AChR clusters in Dok7-overexpressing C2C12 cells. Thus interference by IgG4 antibodies of the LRP4-MuSK interaction will be one pathogenic mechanism of MuSK antibodies, but IgG1-3 MuSK antibodies will also contribute to the reduced AChR density and neuromuscular dysfunction in myasthenia patients with MuSK antibodies.
Collapse
Affiliation(s)
- Inga Koneczny
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Patrick Waters
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Angela Vincent
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
| |
Collapse
|
43
|
Choi HY, Liu Y, Tennert C, Sugiura Y, Karakatsani A, Kröger S, Johnson EB, Hammer RE, Lin W, Herz J. APP interacts with LRP4 and agrin to coordinate the development of the neuromuscular junction in mice. eLife 2013; 2:e00220. [PMID: 23986861 PMCID: PMC3748711 DOI: 10.7554/elife.00220] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 07/18/2013] [Indexed: 12/22/2022] Open
Abstract
ApoE, ApoE receptors and APP cooperate in the pathogenesis of Alzheimer’s disease. Intriguingly, the ApoE receptor LRP4 and APP are also required for normal formation and function of the neuromuscular junction (NMJ). In this study, we show that APP interacts with LRP4, an obligate co-receptor for muscle-specific tyrosine kinase (MuSK). Agrin, a ligand for LRP4, also binds to APP and co-operatively enhances the interaction of APP with LRP4. In cultured myotubes, APP synergistically increases agrin-induced acetylcholine receptor (AChR) clustering. Deletion of the transmembrane domain of LRP4 (LRP4 ECD) results in growth retardation of the NMJ, and these defects are markedly enhanced in APP−/−;LRP4ECD/ECD mice. Double mutant NMJs are significantly reduced in size and number, resulting in perinatal lethality. Our findings reveal novel roles for APP in regulating neuromuscular synapse formation through hetero-oligomeric interaction with LRP4 and agrin and thereby provide new insights into the molecular mechanisms that govern NMJ formation and maintenance. DOI:http://dx.doi.org/10.7554/eLife.00220.001 One of the hallmarks of Alzheimer’s disease is the formation of plaques in the brain by a protein called β-amyloid. This protein is generated by the cleavage of a precursor protein, and mutations in the gene that encodes amyloid precursor protein greatly increase the risk of developing a familial, early-onset form of Alzheimer’s disease in middle age. Individuals with a particular variant of a lipoprotein called ApoE (ApoE4) are also more likely to develop Alzheimer’s disease at a younger age than the rest of the population. Due to its prevalence—approximately 20% of the world’s population are carriers of at least one allele—ApoE4 is the single-most important risk factor for the late-onset form of Alzheimer’s disease. Amyloid precursor protein and the receptors for ApoE—in particular one called LRP4—are also essential for the development of the specialized synapse that forms between motor neurons and muscles. However, the mechanisms by which they, individually or together, contribute to the formation of these neuromuscular junctions are incompletely understood. Now, Choi et al. have shown that amyloid precursor protein and LRP4 interact at the developing neuromuscular junction. A protein called agrin, which is produced by motor neurons and which must bind to LRP4 to induce neuromuscular junction formation, also binds directly to amyloid precursor protein. This latter interaction leads to the formation of a complex between LRP4 and amyloid precursor protein that robustly promotes the formation of the neuromuscular junction. Mutations that remove the part of LRP4 that anchors it to the cell membrane weaken this complex and thus reduce the development of neuromuscular junctions in mice, especially if the animals also lack amyloid precursor protein. These three proteins thus seem to influence the development and maintenance of neuromuscular junctions by regulating the activity of a fourth protein, called MuSK, which is present on the surface of muscle cells. Activation of MuSK by agrin bound to LRP4 promotes the clustering of acetylcholine receptors in the membrane, which is a crucial step in the formation of the neuromuscular junction. Intriguingly, Choi et al. have now shown that amyloid precursor protein can, by interacting directly with LRP4, also activate MuSK even in the absence of agrin, albeit only to a small extent. The work of Choi et al. suggests that the complex formed between agrin, amyloid precursor protein and LRP4 helps to focus the activation of MuSK, and thus the clustering of acetylcholine receptors, to the site of the developing neuromuscular junction. Since all four proteins are also found in the central nervous system, similar processes might well be at work during the development and maintenance of synapses in the brain. Further studies of these interactions, both at the neuromuscular junction and in the brain, should shed new light on both normal synapse formation and the synaptic dysfunction that is seen in Alzheimer’s disease. DOI:http://dx.doi.org/10.7554/eLife.00220.002
Collapse
Affiliation(s)
- Hong Y Choi
- Department of Molecular Genetics , University of Texas Southwestern Medical Center , Dallas , United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Koneczny I, Cossins J, Vincent A. The role of muscle-specific tyrosine kinase (MuSK) and mystery of MuSK myasthenia gravis. J Anat 2013; 224:29-35. [PMID: 23458718 DOI: 10.1111/joa.12034] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2013] [Indexed: 11/28/2022] Open
Abstract
MuSK myasthenia gravis is a rare, severe autoimmune disease of the neuromuscular junction, only identified in 2001, with unclear pathogenic mechanisms. In this review we describe the clinical aspects that distinguish MuSK MG from AChR MG, review what is known about the role of MuSK in the development and function of the neuromuscular junction, and discuss the data that address how the antibodies to MuSK lead to neuromuscular transmission failure.
Collapse
Affiliation(s)
- Inga Koneczny
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | | | | |
Collapse
|
45
|
Zong Y, Jin R. Structural mechanisms of the agrin-LRP4-MuSK signaling pathway in neuromuscular junction differentiation. Cell Mol Life Sci 2012. [PMID: 23178848 DOI: 10.1007/s00018-012-1209-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The neuromuscular junction (NMJ) is the most extensively studied model of neuronal synaptogenesis. Acetylcholine receptor (AChR) clustering on the postsynaptic membrane is a cardinal event in the differentiation of NMJs. AChR clustering and postsynaptic differentiation is orchestrated by sophisticated interactions among three proteins: the neuron-secreted proteoglycan agrin, the co-receptor LRP4, and the muscle-specific receptor tyrosine kinase MuSK. LRP4 and MuSK act as scaffolds for multiple binding partners, resulting in a complex and dynamic network of interacting proteins that is required for AChR clustering. In this review, we discuss the structural basis for NMJ postsynaptic differentiation mediated by the agrin-LRP4-MuSK signaling pathway.
Collapse
Affiliation(s)
- Yinong Zong
- Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | | |
Collapse
|
46
|
Wu H, Lu Y, Shen C, Patel N, Gan L, Xiong WC, Mei L. Distinct roles of muscle and motoneuron LRP4 in neuromuscular junction formation. Neuron 2012; 75:94-107. [PMID: 22794264 DOI: 10.1016/j.neuron.2012.04.033] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2012] [Indexed: 01/07/2023]
Abstract
Neuromuscular junction (NMJ) formation requires precise interaction between motoneurons and muscle fibers. LRP4 is a receptor of agrin that is thought to act in cis to stimulate MuSK in muscle fibers for postsynaptic differentiation. Here we dissected the roles of LRP4 in muscle fibers and motoneurons in NMJ formation by cell-specific mutation. Studies of muscle-specific mutants suggest that LRP4 is involved in deciding where to form AChR clusters in muscle fibers, postsynaptic differentiation, and axon terminal development. LRP4 in HEK293 cells increased synapsin or SV2 puncta in contacting axons of cocultured neurons, suggesting a synaptogenic function. Analysis of LRP4 muscle and motoneuron double mutants and mechanistic studies suggest that NMJ formation may also be regulated by LRP4 in motoneurons, which could serve as agrin's receptor in trans to induce AChR clusters. These observations uncovered distinct roles of LRP4 in motoneurons and muscles in NMJ development.
Collapse
Affiliation(s)
- Haitao Wu
- Institute of Molecular Medicine and Genetics and Department of Neurology, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA 30912, USA
| | | | | | | | | | | | | |
Collapse
|
47
|
Maselli RA, Fernandez JM, Arredondo J, Navarro C, Ngo M, Beeson D, Cagney Ó, Williams DC, Wollmann RL, Yarov-Yarovoy V, Ferns MJ. LG2 agrin mutation causing severe congenital myasthenic syndrome mimics functional characteristics of non-neural (z-) agrin. Hum Genet 2012; 131:1123-35. [PMID: 22205389 PMCID: PMC4795461 DOI: 10.1007/s00439-011-1132-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 12/11/2011] [Indexed: 10/14/2022]
Abstract
We describe a severe form of congenital myasthenic syndrome (CMS) caused by two heteroallelic mutations: a nonsense and a missense mutation in the gene encoding agrin (AGRN). The identified mutations, Q353X and V1727F, are located at the N-terminal and at the second laminin G-like (LG2) domain of agrin, respectively. A motor-point muscle biopsy demonstrated severe disruption of the architecture of the neuromuscular junction (NMJ), including: dispersion and fragmentation of endplate areas with normal expression of acetylcholinesterase; simplification of postsynaptic membranes; pronounced reduction of the axon terminal size; widening of the primary synaptic cleft; and, collection of membranous debris material in the primary synaptic cleft and in the subsynaptic cytoplasm. Expression studies in heterologous cells revealed that the Q353X mutation abolished expression of full-length agrin. Moreover, the V1727F mutation decreased agrin-induced clustering of the acetylcholine receptor (AChR) in cultured C2 muscle cells by >100-fold, and phosphorylation of the MuSK receptor and AChR beta subunit by ~tenfold. Surprisingly, the V1727F mutant also displayed increased binding to α-dystroglycan but decreased binding to a neural (z+) agrin-specific antibody. Our findings demonstrate that agrin mutations can associate with a severe form of CMS and cause profound distortion of the architecture and function of the NMJ. The impaired ability of V1727F agrin to activate MuSK and cluster AChRs, together with its increased affinity to α-dystroglycan, mimics non-neural (z-) agrin and are important determinants of the pathogenesis of the disease.
Collapse
MESH Headings
- Acetylcholinesterase/metabolism
- Adult
- Agrin/chemistry
- Agrin/genetics
- Agrin/metabolism
- Base Sequence
- Cell Line
- Codon, Nonsense
- Dystroglycans/metabolism
- Female
- HEK293 Cells
- Humans
- Male
- Models, Molecular
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Mutation, Missense
- Myasthenic Syndromes, Congenital/genetics
- Myasthenic Syndromes, Congenital/metabolism
- Neuromuscular Junction/metabolism
- Neuromuscular Junction/pathology
- Pedigree
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Sequence Analysis, DNA
Collapse
Affiliation(s)
- Ricardo A. Maselli
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - Jose M. Fernandez
- Service of Clinical Neurophysiology. University Hospital of Vigo, Vigo (Pontevedra), Spain
| | - Juan Arredondo
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - Carmen Navarro
- Department of Pathology, University Hospital of Vigo and CIBERER (Centro de Investigacion Biomedica en Red en Enfermedades Raras), Vigo (Pontevedra), Spain
| | - Maian Ngo
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Órla Cagney
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - D. Colette Williams
- Veterinary Medical Teaching Hospital, University of California Davis, Davis, California, 95616, USA
| | - Robert L. Wollmann
- Department of Pathology, University of Chicago, Chicago, Illinois, 60637, USA
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California Davis, Davis, California 95616, USA
| | - Michael J Ferns
- Department of Physiology and Membrane Biology, University of California Davis, Davis, California 95616, USA
- Department of Anesthesiology, University of California Davis, Davis, California 95616, USA
| |
Collapse
|
48
|
Abstract
The receptor tyrosine kinase MuSK is indispensable for nerve-muscle synapse formation and maintenance. MuSK is necessary for prepatterning of the endplate zone anlage and as a signaling receptor for agrin-mediated postsynaptic differentiation. MuSK-associated proteins such as Dok7, LRP4, and Wnt11r are involved in these early events in neuromuscular junction formation. However, the mechanisms regulating synapse stability are poorly understood. Here we examine a novel role for the extracellular matrix protein biglycan in synapse stability. Synaptic development in fetal and early postnatal biglycan null (bgn(-/o)) muscle is indistinguishable from wild-type controls. However, by 5 weeks after birth, nerve-muscle synapses in bgn(-/o) mice are abnormal as judged by the presence of perijunctional folds, increased segmentation, and focal misalignment of acetylcholinesterase and AChRs. These observations indicate that previously occupied presynaptic and postsynaptic territory has been vacated. Biglycan binds MuSK and the levels of this receptor tyrosine kinase are selectively reduced at bgn(-/o) synapses. In bgn(-/o) myotubes, the initial stages of agrin-induced MuSK phosphorylation and AChR clustering are normal, but the AChR clusters are unstable. This stability defect can be substantially rescued by the addition of purified biglycan. Together, these results indicate that biglycan is an extracellular ligand for MuSK that is important for synapse stability.
Collapse
|
49
|
Bogdanik LP, Burgess RW. A valid mouse model of AGRIN-associated congenital myasthenic syndrome. Hum Mol Genet 2011; 20:4617-33. [PMID: 21890498 DOI: 10.1093/hmg/ddr396] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are inherited diseases affecting the neuromuscular junction (NMJ). Mutations in AGRIN (AGRN) and other genes in the AGRIN signaling pathway cause CMS, and gene targeting studies in mice confirm the importance of this pathway for NMJ formation. However, these mouse mutations are complete loss-of-function alleles that result in an embryonic failure of NMJ formation, and homozygous mice do not survive postpartum. Therefore, mouse models of AGRIN-related CMS that would allow preclinical testing or studies of postnatal disease progression are lacking. Using chemical mutagenesis in mice, we identified a point mutation in Agrn that results in a partial loss-of-function allele, creating a valid model of CMS. The mutation changes phenylalanine 1061 to serine in the SEA domain of AGRIN, a poorly characterized motif shared by other extracellular proteoglycans. NMJs in homozygous mice progressively degrade postnataly. Severity differs with genetic background, in different muscles, and in different regions within a muscle in a pattern matching mouse models of motor neuron disease. Mutant NMJs have decreased acetylcholine receptor density and an increased subsynaptic reticulum, evident by electron microscopy. Synapses eventually denervate and the muscles atrophy. Molecularly, several factors contribute to the partial loss of AGRIN's function. The mutant protein is found at NMJs, but is processed differently than wild-type, with decreased glycosylation, changes in sensitivity to the protease neurotrypsin and other proteolysis, and less efficient externalization and secretion. Therefore, the Agrn point mutation is a model for CMS caused by Agrn mutations and potentially other related neuromuscular diseases.
Collapse
|
50
|
Rimer M. Emerging roles for MAP kinases in agrin signaling. Commun Integr Biol 2011; 4:143-6. [PMID: 21655426 DOI: 10.4161/cib.4.2.14357] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 11/19/2022] Open
Abstract
Information between neurons and the target cells they innervate passes through sites of functional contact called synapses. How synapses form and are altered by sensory or cognitive experience is central to understand nervous system function. Studies of synapse formation and plasticity have concentrated on a few "model" synapses. The vertebrate neuromuscular junction (NMJ), the synapse between a motoneuron in the spinal cord and a skeletal muscle fiber, is one such model synapse. The extracellular matrix proteoglycan agrin plays an essential organizing role at the NMJ. Agrin is also present at some synapses in the brain and in other organs in the periphery, but its function outside the NMJ is unclear. The core signaling pathway for agrin at the NMJ, which is still incompletely defined, includes molecules specifically involved in this cascade and molecules used in other signaling pathways in many cells. Mitogen-activated protein kinases (MAPKs) are evolutionarily conserved components of intracellular signaling modules that control a myriad of cellular processes. This article reviews emerging evidence that suggests that MAPKs are involved in agrin signaling at the NMJ and in the putative functions of agrin in the formation of a subset of synapses in the brain.
Collapse
Affiliation(s)
- Mendell Rimer
- Department of Neuroscience & Experimental Therapeutics; College of Medicine; Texas A&M Health Science Center; College Station, TX USA
| |
Collapse
|