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Dolmatov IY, Nizhnichenko VA. Extracellular Matrix of Echinoderms. Mar Drugs 2023; 21:417. [PMID: 37504948 PMCID: PMC10381214 DOI: 10.3390/md21070417] [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: 06/09/2023] [Revised: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 07/29/2023] Open
Abstract
This review considers available data on the composition of the extracellular matrix (ECM) in echinoderms. The connective tissue in these animals has a rather complex organization. It includes a wide range of structural ECM proteins, as well as various proteases and their inhibitors. Members of almost all major groups of collagens, various glycoproteins, and proteoglycans have been found in echinoderms. There are enzymes for the synthesis of structural proteins and their modification by polysaccharides. However, the ECM of echinoderms substantially differs from that of vertebrates by the lack of elastin, fibronectins, tenascins, and some other glycoproteins and proteoglycans. Echinoderms have a wide variety of proteinases, with serine, cysteine, aspartic, and metal peptidases identified among them. Their active centers have a typical structure and can break down various ECM molecules. Echinoderms are also distinguished by a wide range of proteinase inhibitors. The complex ECM structure and the variety of intermolecular interactions evidently explain the complexity of the mechanisms responsible for variations in the mechanical properties of connective tissue in echinoderms. These mechanisms probably depend not only on the number of cross-links between the molecules, but also on the composition of ECM and the properties of its proteins.
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Affiliation(s)
- Igor Yu Dolmatov
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Palchevsky 17, 690041 Vladivostok, Russia
| | - Vladimir A Nizhnichenko
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Palchevsky 17, 690041 Vladivostok, Russia
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2
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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3
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Abstract
The patient had suffered from both proximal and distal limb weakness since her early childhood, without the involvement of ocular or respiratory muscles. Repetitive nerve stimulation (RNS) at 3 Hz showed significant decrement in the area and amplitude of the compound muscle action potential (CMAP) on the right abductor digiti minimi (26%) and trapezius (17%). Whole-exon sequencing revealed two novel heterozygous mutations (p.Q1406Rfs*29 and p.R1521H) in the LG1 domain of agrin, which were deemed likely pathogenic for congenital myasthenic syndromes (CMS) according to a bioinformatics analysis. The patient showed remarkable improvement after treatment with salbutamol. This case expanded the mutation spectrum of AGRN.
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Affiliation(s)
- Ping Xia
- Department of Neurology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, China
| | - Fei Xie
- Department of Neurology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, China
| | - Zhi-Jie Zhou
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, China
| | - Wen Lv
- Department of Neurology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, China
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4
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Jacquier A, Risson V, Simonet T, Roussange F, Lacoste N, Ribault S, Carras J, Theuriet J, Girard E, Grosjean I, Le Goff L, Kröger S, Meltoranta J, Bauché S, Sternberg D, Fournier E, Kostera-Pruszczyk A, O’Connor E, Eymard B, Lochmüller H, Martinat C, Schaeffer L. Severe congenital myasthenic syndromes caused by agrin mutations affecting secretion by motoneurons. Acta Neuropathol 2022; 144:707-731. [PMID: 35948834 PMCID: PMC9468088 DOI: 10.1007/s00401-022-02475-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 07/25/2022] [Accepted: 07/25/2022] [Indexed: 01/28/2023]
Abstract
Congenital myasthenic syndromes (CMS) are predominantly characterized by muscle weakness and fatigability and can be caused by a variety of mutations in genes required for neuromuscular junction formation and maintenance. Among them, AGRN encodes agrin, an essential synaptic protein secreted by motoneurons. We have identified severe CMS patients with uncharacterized p.R1671Q, p.R1698P and p.L1664P mutations in the LG2 domain of agrin. Overexpression in primary motoneurons cultures in vitro and in chick spinal motoneurons in vivo revealed that the mutations modified agrin trafficking, leading to its accumulation in the soma and/or in the axon. Expression of mutant agrins in cultured cells demonstrated accumulation of agrin in the endoplasmic reticulum associated with induction of unfolded protein response (UPR) and impaired secretion in the culture medium. Interestingly, evaluation of the specific activity of individual agrins on AChR cluster formation indicated that when secreted, mutant agrins retained a normal capacity to trigger the formation of AChR clusters. To confirm agrin accumulation and secretion defect, iPS cells were derived from a patient and differentiated into motoneurons. Patient iPS-derived motoneurons accumulated mutant agrin in the soma and increased XBP1 mRNA splicing, suggesting UPR activation. Moreover, co-cultures of patient iPS-derived motoneurons with myotubes confirmed the deficit in agrin secretion and revealed a reduction in motoneuron survival. Altogether, we report the first mutations in AGRN gene that specifically affect agrin secretion by motoneurons. Interestingly, the three patients carrying these mutations were initially suspected of spinal muscular atrophy (SMA). Therefore, in the presence of patients with a clinical presentation of SMA but without mutation in the SMN1 gene, it can be worth to look for mutations in AGRN.
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Affiliation(s)
- Arnaud Jacquier
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France ,grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Groupement Est, Bron, France
| | - Valérie Risson
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France
| | - Thomas Simonet
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France ,grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Groupement Est, Bron, France
| | - Florine Roussange
- grid.503216.30000 0004 0618 2124INSERM/UEPS UMR 861, Paris Saclay Université, I-STEM, 91100 Corbeil-Essonnes, France
| | - Nicolas Lacoste
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France
| | - Shams Ribault
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France ,grid.413852.90000 0001 2163 3825Service de Médecine Physique et de Réadaptation, Hôpital Henry Gabrielle, Hospices Civils de Lyon, 69230 Saint-Genis-Laval, France
| | - Julien Carras
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France ,grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Groupement Est, Bron, France
| | - Julian Theuriet
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France ,grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Groupement Est, Bron, France
| | - Emmanuelle Girard
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France
| | - Isabelle Grosjean
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France
| | - Laure Le Goff
- grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Groupement Est, Bron, France
| | - Stephan Kröger
- Department of Physiological Genomics, Biomedical Center, Planegg, Martinsried, Germany
| | - Julia Meltoranta
- Department of Physiological Genomics, Biomedical Center, Planegg, Martinsried, Germany
| | - Stéphanie Bauché
- grid.462844.80000 0001 2308 1657Inserm U 1127, CNRS UMR 7225, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, Sorbonne Universités, 75013 Paris, France
| | - Damien Sternberg
- grid.462844.80000 0001 2308 1657Inserm U 1127, CNRS UMR 7225, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, Sorbonne Universités, 75013 Paris, France ,grid.411439.a0000 0001 2150 9058APHP, UF Cardiogénétique et Myogénétique, Service de Biochimie Métabolique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Emmanuel Fournier
- grid.462844.80000 0001 2308 1657Inserm U 1127, CNRS UMR 7225, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, Sorbonne Universités, 75013 Paris, France ,grid.411439.a0000 0001 2150 9058AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France ,grid.462844.80000 0001 2308 1657Département d’Éthique de l’Université et des enseignements de Physiologie de la Faculté de Médecine Pitié-Salpêtrière, 75013 Paris, France
| | - Anna Kostera-Pruszczyk
- grid.13339.3b0000000113287408Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Emily O’Connor
- grid.28046.380000 0001 2182 2255Division of Neurology, Department of Medicine, Children’s Hospital of Eastern Ontario Research Institute, The Ottawa Hospital and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Bruno Eymard
- grid.462844.80000 0001 2308 1657Inserm U 1127, CNRS UMR 7225, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, Sorbonne Universités, 75013 Paris, France ,grid.411439.a0000 0001 2150 9058AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Hanns Lochmüller
- grid.28046.380000 0001 2182 2255Division of Neurology, Department of Medicine, Children’s Hospital of Eastern Ontario Research Institute, The Ottawa Hospital and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Cécile Martinat
- grid.503216.30000 0004 0618 2124INSERM/UEPS UMR 861, Paris Saclay Université, I-STEM, 91100 Corbeil-Essonnes, France
| | - Laurent Schaeffer
- Pathophysiology and Genetics of Neuron and Muscle, Faculté de Médecine Lyon Est, CNRS UMR 5261, INSERM U1315, Université Lyon1, Lyon, France ,grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Groupement Est, Bron, France
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5
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Webster RG, Vanhaesebrouck AE, Maxwell SE, Cossins JA, Liu W, Ueta R, Yamanashi Y, Beeson DMW. Effect of salbutamol on neuromuscular junction function and structure in a mouse model of DOK7 congenital myasthenia. Hum Mol Genet 2021; 29:2325-2336. [PMID: 32543656 PMCID: PMC7424765 DOI: 10.1093/hmg/ddaa116] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 06/07/2020] [Accepted: 06/08/2020] [Indexed: 12/28/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are characterized by fatigable muscle weakness resulting from impaired neuromuscular transmission. β2-adrenergic agonists are an effective treatment for DOK7-CMS. DOK7 is a component within the AGRN-LRP4-MUSK-DOK7 signalling pathway that is key for the formation and maintenance of the synaptic structure of the neuromuscular junction (NMJ). The precise mechanism of action of β2-adrenergic agonists at the NMJ is not fully understood. In this study, we investigated whether β2-adrenergic agonists improve both neurotransmission and structural integrity of the NMJ in a mouse model of DOK7-CMS. Ex-vivo electrophysiological techniques and microscopy of the NMJ were used to study the effect of salbutamol, a β2-adrenergic agonist, on synaptic structure and function. DOK7-CMS model mice displayed a severe phenotype with reduced weight gain and perinatal lethality. Salbutamol treatment improved weight gain and survival in DOK7 myasthenic mice. Model animals had fewer active NMJs, detectable by endplate recordings, compared with age-matched wild-type littermates. Salbutamol treatment increased the number of detectable NMJs during endplate recording. Correspondingly, model mice had fewer acetylcholine receptor-stained NMJs detected by fluorescent labelling, but following salbutamol treatment an increased number were detectable. The data demonstrate that salbutamol can prolong survival and increase NMJ number in a severe model of DOK7-CMS.
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Affiliation(s)
- Richard G Webster
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - An E Vanhaesebrouck
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Susan E Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Judith A Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Weiwei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Ryo Ueta
- Division of Genetics, Department of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo 135-8550, Japan
| | - Yuji Yamanashi
- Division of Genetics, Department of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo 135-8550, Japan
| | - David M W Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
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6
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Ohkawara B, Ito M, Ohno K. Secreted Signaling Molecules at the Neuromuscular Junction in Physiology and Pathology. Int J Mol Sci 2021; 22:ijms22052455. [PMID: 33671084 PMCID: PMC7957818 DOI: 10.3390/ijms22052455] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 02/08/2023] Open
Abstract
Signal transduction at the neuromuscular junction (NMJ) is affected in many human diseases, including congenital myasthenic syndromes (CMS), myasthenia gravis, Lambert–Eaton myasthenic syndrome, Isaacs’ syndrome, Schwartz–Jampel syndrome, Fukuyama-type congenital muscular dystrophy, amyotrophic lateral sclerosis, and sarcopenia. The NMJ is a prototypic cholinergic synapse between the motor neuron and the skeletal muscle. Synaptogenesis of the NMJ has been extensively studied, which has also been extrapolated to further understand synapse formation in the central nervous system. Studies of genetically engineered mice have disclosed crucial roles of secreted molecules in the development and maintenance of the NMJ. In this review, we focus on the secreted signaling molecules which regulate the clustering of acetylcholine receptors (AChRs) at the NMJ. We first discuss the signaling pathway comprised of neural agrin and its receptors, low-density lipoprotein receptor-related protein 4 (Lrp4) and muscle-specific receptor tyrosine kinase (MuSK). This pathway drives the clustering of acetylcholine receptors (AChRs) to ensure efficient signal transduction at the NMJ. We also discuss three secreted molecules (Rspo2, Fgf18, and connective tissue growth factor (Ctgf)) that we recently identified in the Wnt/β-catenin and fibroblast growth factors (FGF) signaling pathways. The three secreted molecules facilitate the clustering of AChRs by enhancing the agrin-Lrp4-MuSK signaling pathway.
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Affiliation(s)
- Bisei Ohkawara
- Correspondence: ; Tel.: +81-52-744-2447; Fax: +81-52-744-2449
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7
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The congenital myasthenic syndromes: expanding genetic and phenotypic spectrums and refining treatment strategies. Curr Opin Neurol 2020; 32:696-703. [PMID: 31361628 PMCID: PMC6735524 DOI: 10.1097/wco.0000000000000736] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Congenital myasthenic syndromes (CMS) are a group of heterogeneous inherited disorders caused by mutations in genes encoding proteins whose function is essential for the integrity of neuromuscular transmission. This review updates the reader on the expanding phenotypic spectrum and suggested improved treatment strategies.
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8
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Ohkawara B, Shen X, Selcen D, Nazim M, Bril V, Tarnopolsky MA, Brady L, Fukami S, Amato AA, Yis U, Ohno K, Engel AG. Congenital myasthenic syndrome-associated agrin variants affect clustering of acetylcholine receptors in a domain-specific manner. JCI Insight 2020; 5:132023. [PMID: 32271162 DOI: 10.1172/jci.insight.132023] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 02/28/2020] [Indexed: 12/17/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are caused by mutations in molecules expressed at the neuromuscular junction. We report clinical, structural, ultrastructural, and electrophysiologic features of 4 CMS patients with 6 heteroallelic variants in AGRN, encoding agrin. One was a 7.9-kb deletion involving the N-terminal laminin-binding domain. Another, c.4744G>A - at the last nucleotide of exon 26 - caused skipping of exon 26. Four missense mutations (p.S1180L, p.R1509W, p.G1675S, and p.Y1877D) expressed in conditioned media decreased AChR clusters in C2C12 myotubes. The agrin-enhanced phosphorylation of MuSK was markedly attenuated by p.Y1877D in the LG3 domain and moderately attenuated by p.R1509W in the LG1 domain but not by the other 2 mutations. The p.S1180L mutation in the SEA domain facilitated degradation of secreted agrin. The p.G1675S mutation in the LG2 domain attenuated anchoring of agrin to the sarcolemma by compromising its binding to heparin. Anchoring of agrin with p.R1509W in the LG1 domain was similarly attenuated. Mutations of agrin affect AChR clustering by enhancing agrin degradation or by suppressing MuSK phosphorylation and/or by compromising anchoring of agrin to the sarcolemma of the neuromuscular junction.
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Affiliation(s)
- Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - XinMing Shen
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Mohammad Nazim
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Vera Bril
- Vera Bril, Department of Neurology, University of Toronto, Toronto, Canada
| | - Mark A Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, Ontario, Canada
| | - Lauren Brady
- Department of Pediatrics, McMaster University Medical Center, Hamilton, Ontario, Canada
| | - Sae Fukami
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Anthony A Amato
- Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Uluc Yis
- Division of Child Neurology, Department of Pediatrics, School of Medicine, Dokuz Eylul University, Izmir, Turkey
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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9
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Wang A, Xiao Y, Huang P, Liu L, Xiong J, Li J, Mao D, Liu L. Novel NtA and LG1 Mutations in Agrin in a Single Patient Causes Congenital Myasthenic Syndrome. Front Neurol 2020; 11:239. [PMID: 32328026 PMCID: PMC7160337 DOI: 10.3389/fneur.2020.00239] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 03/12/2020] [Indexed: 12/27/2022] Open
Abstract
Congenital myasthenic syndrome (CMS) is a group of genetic disorders of neuromuscular transmission that is characterized by muscle weakness. A mutation in the gene encoding agrin (AGRN) is a rare cause of CMS, and only a few families or isolated cases have been reported. We reported a pediatric proband exhibiting muscle weakness in the trunk and limbs with skeletal malformation and intellectual disability and performed whole-exome sequencing (WES) of the proband parent-offspring trio. Results revealed a new compound heterozygous mutation in AGRN: c.125A>C (p.Glu42Ala) in the N-terminal agrin domain (NtA) and c.4516G>A (p.Ala1506Thr) in the laminin G1 domain (LG1). Bioinformatic analysis predicted the mutation as possibly pathogenic. The new compound heterozygous mutation in AGRN may disrupt agrin's known function of bridging laminin and α-dystroglycan and undermine the formation and maintenance of the neuromuscular junction (NMJ) via both muscular and neural agrin pathways. It may also induce secondary peripheral neuropathy and skeletal malformation.
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Affiliation(s)
- Aiping Wang
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yangyang Xiao
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Peng Huang
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Lingjuan Liu
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jie Xiong
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jian Li
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Ding'an Mao
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Liqun Liu
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
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10
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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.
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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
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11
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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.
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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
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12
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Dempsey CE, Bigotti MG, Adams JC, Brancaccio A. Analysis of α-Dystroglycan/LG Domain Binding Modes: Investigating Protein Motifs That Regulate the Affinity of Isolated LG Domains. Front Mol Biosci 2019; 6:18. [PMID: 30984766 PMCID: PMC6450144 DOI: 10.3389/fmolb.2019.00018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 03/07/2019] [Indexed: 12/25/2022] Open
Abstract
Dystroglycan (DG) is an adhesion complex that links the cytoskeleton to the surrounding extracellular matrix in skeletal muscle and a wide variety of other tissues. It is composed of a highly glycosylated extracellular α-DG associated noncovalently with a transmembrane β-DG whose cytodomain interacts with dystrophin and its isoforms. Alpha-dystroglycan (α-DG) binds tightly and in a calcium-dependent fashion to multiple extracellular proteins and proteoglycans, each of which harbors at least one, or, more frequently, tandem arrays of laminin-globular (LG) domains. Considerable biochemical and structural work has accumulated on the α-DG-binding LG domains, highlighting a significant heterogeneity in ligand-binding properties of domains from different proteins as well as between single and multiple LG domains within the same protein. Here we review biochemical, structural, and functional information on the LG domains reported to bind α-dystroglycan. In addition, we have incorporated bioinformatics and modeling to explore whether specific motifs responsible for α-dystroglycan recognition can be identified within isolated LG domains. In particular, we analyzed the LG domains of slits and agrin as well as those of paradigmatic α-DG non-binders such as laminin-α3. While some stretches of basic residues may be important, no universally conserved motifs could be identified. However, the data confirm that the coordinated calcium atom within the LG domain is needed to establish an interaction with the sugars of α-DG, although it appears that this alone is insufficient to mediate significant α-DG binding. We develop a scenario involving different binding modes of a single LG domain unit, or tandemly repeated units, with α-DG. A variability of binding modes might be important to generate a range of affinities to allow physiological regulation of this interaction, reflecting its crucial biological importance.
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Affiliation(s)
| | | | - Josephine C Adams
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Andrea Brancaccio
- School of Biochemistry, University of Bristol, Bristol, United Kingdom.,Istituto di Chimica del Riconoscimento Molecolare - CNR, Università Cattolica del Sacro Cuore, Rome, Italy
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13
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Nicolau S, Milone M. The Electrophysiology of Presynaptic Congenital Myasthenic Syndromes With and Without Facilitation: From Electrodiagnostic Findings to Molecular Mechanisms. Front Neurol 2019; 10:257. [PMID: 30941097 PMCID: PMC6433874 DOI: 10.3389/fneur.2019.00257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/26/2019] [Indexed: 11/13/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited disorders of neuromuscular transmission most commonly presenting with early onset fatigable weakness, ptosis, and ophthalmoparesis. CMS are classified according to the localization of the causative molecular defect. CMS with presynaptic dysfunction can be caused by mutations in several different genes, including those involved in acetylcholine synthesis, its packaging into synaptic vesicles, vesicle docking, and release from the presynaptic nerve terminal and neuromuscular junction development and maintenance. Electrodiagnostic testing is key in distinguishing CMS from other neuromuscular disorders with similar clinical features as well as for revealing features pointing to a specific molecular diagnosis. A decremental response on low-frequency repetitive nerve stimulation (RNS) is present in most presynaptic CMS. In CMS with deficits in acetylcholine resynthesis however, a decrement may only appear after conditioning with exercise or high-frequency RNS and characteristically displays a slow recovery. Facilitation occurs in CMS caused by mutations in VAMP1, UNC13A, SYT2, AGRN, LAMA5. By contrast, facilitation is absent in the other presynaptic CMS described to date. An understanding of the underlying molecular mechanisms therefore assists the interpretation of electrodiagnostic findings in patients with suspected CMS.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
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14
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Cardoso AL, Fernandes A, Aguilar-Pimentel JA, de Angelis MH, Guedes JR, Brito MA, Ortolano S, Pani G, Athanasopoulou S, Gonos ES, Schosserer M, Grillari J, Peterson P, Tuna BG, Dogan S, Meyer A, van Os R, Trendelenburg AU. Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases. Ageing Res Rev 2018; 47:214-277. [PMID: 30071357 DOI: 10.1016/j.arr.2018.07.004] [Citation(s) in RCA: 290] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/08/2018] [Accepted: 07/10/2018] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel. METHODS Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers. RESULTS A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified. CONCLUSION Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.
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Rodríguez Cruz PM, Palace J, Beeson D. The Neuromuscular Junction and Wide Heterogeneity of Congenital Myasthenic Syndromes. Int J Mol Sci 2018; 19:ijms19061677. [PMID: 29874875 PMCID: PMC6032286 DOI: 10.3390/ijms19061677] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders characterised by impaired neuromuscular transmission. This review provides an overview on CMS and highlights recent advances in the field, including novel CMS causative genes and improved therapeutic strategies. CMS due to mutations in SLC5A7 and SLC18A3, impairing the synthesis and recycling of acetylcholine, have recently been described. In addition, a novel group of CMS due to mutations in SNAP25B, SYT2, VAMP1, and UNC13A1 encoding molecules implicated in synaptic vesicles exocytosis has been characterised. The increasing number of presynaptic CMS exhibiting CNS manifestations along with neuromuscular weakness demonstrate that the myasthenia can be only a small part of a much more extensive disease phenotype. Moreover, the spectrum of glycosylation abnormalities has been increased with the report that GMPPB mutations can cause CMS, thus bridging myasthenic disorders with dystroglycanopathies. Finally, the discovery of COL13A1 mutations and laminin α5 deficiency has helped to draw attention to the role of extracellular matrix proteins for the formation and maintenance of muscle endplates. The benefit of β2-adrenergic agonists alone or combined with pyridostigmine or 3,4-Dyaminopiridine is increasingly being reported for different subtypes of CMS including AChR-deficiency and glycosylation abnormalities, thus expanding the therapeutic repertoire available.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
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