1
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Hann SH, Kim SY, Kim YL, Jo YW, Kang JS, Park H, Choi SY, Kong YY. Depletion of SMN protein in mesenchymal progenitors impairs the development of bone and neuromuscular junction in spinal muscular atrophy. eLife 2024; 12:RP92731. [PMID: 38318851 PMCID: PMC10945524 DOI: 10.7554/elife.92731] [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] [Indexed: 02/07/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by the deficiency of the survival motor neuron (SMN) protein, which leads to motor neuron dysfunction and muscle atrophy. In addition to the requirement for SMN in motor neurons, recent studies suggest that SMN deficiency in peripheral tissues plays a key role in the pathogenesis of SMA. Using limb mesenchymal progenitor cell (MPC)-specific SMN-depleted mouse models, we reveal that SMN reduction in limb MPCs causes defects in the development of bone and neuromuscular junction (NMJ). Specifically, these mice exhibited impaired growth plate homeostasis and reduced insulin-like growth factor (IGF) signaling from chondrocytes, rather than from the liver. Furthermore, the reduction of SMN in fibro-adipogenic progenitors (FAPs) resulted in abnormal NMJ maturation, altered release of neurotransmitters, and NMJ morphological defects. Transplantation of healthy FAPs rescued the morphological deterioration. Our findings highlight the significance of mesenchymal SMN in neuromusculoskeletal pathogenesis of SMA and provide insights into potential therapeutic strategies targeting mesenchymal cells for the treatment of SMA.
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Affiliation(s)
- Sang-Hyeon Hann
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seon-Yong Kim
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Ye Lynne Kim
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Young-Woo Jo
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jong-Seol Kang
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hyerim Park
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Se-Young Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Young-Yun Kong
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
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2
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Ojeda J, Vergara M, Ávila A, Henríquez JP, Fehlings M, Vidal PM. Impaired communication at the neuromotor axis during Degenerative Cervical Myelopathy. Front Cell Neurosci 2024; 17:1316432. [PMID: 38269114 PMCID: PMC10806149 DOI: 10.3389/fncel.2023.1316432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024] Open
Abstract
Degenerative Cervical Myelopathy (DCM) is a progressive neurological condition characterized by structural alterations in the cervical spine, resulting in compression of the spinal cord. While clinical manifestations of DCM are well-documented, numerous unanswered questions persist at the molecular and cellular levels. In this study, we sought to investigate the neuromotor axis during DCM. We use a clinically relevant mouse model, where after 3 months of DCM induction, the sensorimotor tests revealed a significant reduction in both locomotor activity and muscle strength compared to the control group. Immunohistochemical analyses showed alterations in the gross anatomy of the cervical spinal cord segment after DCM. These changes were concomitant with the loss of motoneurons and a decrease in the number of excitatory synaptic inputs within the spinal cord. Additionally, the DCM group exhibited a reduction in the endplate surface, which correlated with diminished presynaptic axon endings in the supraspinous muscles. Furthermore, the biceps brachii (BB) muscle exhibited signs of atrophy and impaired regenerative capacity, which inversely correlated with the transversal area of remnants of muscle fibers. Additionally, metabolic assessments in BB muscle indicated an increased proportion of oxidative skeletal muscle fibers. In line with the link between neuromotor disorders and gut alterations, DCM mice displayed smaller mucin granules in the mucosa layer without damage to the epithelial barrier in the colon. Notably, a shift in the abundance of microbiota phylum profiles reveals an elevated Firmicutes-to-Bacteroidetes ratio-a consistent hallmark of dysbiosis that correlates with alterations in gut microbiota-derived metabolites. Additionally, treatment with short-chain fatty acids stimulated the differentiation of the motoneuron-like NSC34 cell line. These findings shed light on the multifaceted nature of DCM, resembling a synaptopathy that disrupts cellular communication within the neuromotor axis while concurrently exerting influence on other systems. Notably, the colon emerges as a focal point, experiencing substantial perturbations in both mucosal barrier integrity and the delicate balance of intestinal microbiota.
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Affiliation(s)
- Jorge Ojeda
- Neuroimmunology and Regeneration of the Central Nervous System Unit, Biomedical Science Research Laboratory, Basic Sciences Department, Faculty of Medicine, Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Mayra Vergara
- Neuroimmunology and Regeneration of the Central Nervous System Unit, Biomedical Science Research Laboratory, Basic Sciences Department, Faculty of Medicine, Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Ariel Ávila
- Developmental Neurobiology Unit, Biomedical Science Research Laboratory, Basic Sciences Department, Faculty of Medicine, Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Juan Pablo Henríquez
- Neuromuscular Studies Lab (NeSt Lab), Instituto de Anatomía, Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Michael Fehlings
- Department of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Spinal Program, University Health Network, Toronto Western Hospital, Toronto, ON, Canada
| | - Pia M. Vidal
- Neuroimmunology and Regeneration of the Central Nervous System Unit, Biomedical Science Research Laboratory, Basic Sciences Department, Faculty of Medicine, Universidad Católica de la Santísima Concepción, Concepción, Chile
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3
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Rashid S, Dimitriadi M. Autophagy in spinal muscular atrophy: from pathogenic mechanisms to therapeutic approaches. Front Cell Neurosci 2024; 17:1307636. [PMID: 38259504 PMCID: PMC10801191 DOI: 10.3389/fncel.2023.1307636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 12/14/2023] [Indexed: 01/24/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by the depletion of the ubiquitously expressed survival motor neuron (SMN) protein. While the genetic cause of SMA has been well documented, the exact mechanism(s) by which SMN depletion results in disease progression remain elusive. A wide body of evidence has highlighted the involvement and dysregulation of autophagy in SMA. Autophagy is a highly conserved lysosomal degradation process which is necessary for cellular homeostasis; defects in the autophagic machinery have been linked with a wide range of neurodegenerative disorders, including amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. The pathway is particularly known to prevent neurodegeneration and has been suggested to act as a neuroprotective factor, thus presenting an attractive target for novel therapies for SMA patients. In this review, (a) we provide for the first time a comprehensive summary of the perturbations in the autophagic networks that characterize SMA development, (b) highlight the autophagic regulators which may play a key role in SMA pathogenesis and (c) propose decreased autophagic flux as the causative agent underlying the autophagic dysregulation observed in these patients.
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Affiliation(s)
| | - Maria Dimitriadi
- School of Life and Medical Science, University of Hertfordshire, Hatfield, United Kingdom
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4
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Cadile F, Recchia D, Ansaldo M, Rossi P, Rastelli G, Boncompagni S, Brocca L, Pellegrino MA, Canepari M. Diaphragm Fatigue in SMNΔ7 Mice and Its Molecular Determinants: An Underestimated Issue. Int J Mol Sci 2023; 24:14953. [PMID: 37834400 PMCID: PMC10574014 DOI: 10.3390/ijms241914953] [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: 09/11/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a genetic disorder characterized by the loss of spinal motor neurons leading to muscle weakness and respiratory failure. Mitochondrial dysfunctions are found in the skeletal muscle of patients with SMA. For obvious ethical reasons, the diaphragm muscle is poorly studied, notwithstanding the very important role that respiratory involvement plays in SMA mortality. The main goal of this study was to investigate diaphragm functionality and the underlying molecular adaptations in SMNΔ7 mice, a mouse model that exhibits symptoms similar to that of patients with intermediate type II SMA. Functional, biochemical, and molecular analyses on isolated diaphragm were performed. The obtained results suggest the presence of an intrinsic energetic imbalance associated with mitochondrial dysfunction and a significant accumulation of reactive oxygen species (ROS). In turn, ROS accumulation can affect muscle fatigue, cause diaphragm wasting, and, in the long run, respiratory failure in SMNΔ7 mice. Exposure to the antioxidant molecule ergothioneine leads to the functional recovery of the diaphragm, confirming the presence of mitochondrial impairment and redox imbalance. These findings suggest the possibility of carrying out a dietary supplementation in SMNΔ7 mice to preserve their diaphragm function and increase their lifespan.
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Affiliation(s)
- Francesca Cadile
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Deborah Recchia
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (D.R.); (P.R.)
| | - Massimiliano Ansaldo
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Paola Rossi
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (D.R.); (P.R.)
| | - Giorgia Rastelli
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (G.R.); (S.B.)
| | - Simona Boncompagni
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (G.R.); (S.B.)
- Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy
| | - Lorenza Brocca
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Monica Canepari
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
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5
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Ponomarev AS, Chulpanova DS, Yanygina LM, Solovyeva VV, Rizvanov AA. Emerging Gene Therapy Approaches in the Management of Spinal Muscular Atrophy (SMA): An Overview of Clinical Trials and Patent Landscape. Int J Mol Sci 2023; 24:13743. [PMID: 37762045 PMCID: PMC10530942 DOI: 10.3390/ijms241813743] [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: 06/30/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disease that is characterized by progressive muscle atrophy (degeneration), including skeletal muscles in charge of the ability to move. SMA is caused by defects in the SMN1 gene (Survival of Motor Neuron 1) which encodes a protein crucial for the survival and functionality of neuron cells called motor neurons. Decreased level of functioning SMN protein leads to progressive degeneration of alpha-motor neurons performing muscular motility. Over the past decade, many strategies directed for SMN-level-restoration emerged, such as gene replacement therapy (GRT), CRISPR/Cas9-based gene editing, usage of antisense oligonucleotides and small-molecule modulators, and all have been showing their perspectives in SMA therapy. In this review, modern SMA therapy strategies are described, making it a valuable resource for researchers, clinicians and everyone interested in the progress of therapy of this serious disorder.
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Affiliation(s)
| | | | | | | | - Albert A. Rizvanov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia; (A.S.P.); (D.S.C.); (L.M.Y.); (V.V.S.)
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6
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Ojala KS, Kaufhold CJ, Davey MR, Yang D, Liang M, Wipf P, Badawi Y, Meriney SD. Potentiation of neuromuscular transmission by a small molecule calcium channel gating modifier improves motor function in a severe spinal muscular atrophy mouse model. Hum Mol Genet 2023; 32:1901-1911. [PMID: 36757138 DOI: 10.1093/hmg/ddad019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/03/2023] [Accepted: 01/24/2023] [Indexed: 02/10/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a monogenic disease that clinically manifests as severe muscle weakness owing to neurotransmission defects and motoneuron degeneration. Individuals affected by SMA experience neuromuscular weakness that impacts functional activities of daily living. We have used a mouse model of severe SMA (SMNΔ7) to test whether a calcium channel gating modifier (GV-58), alone or in combination with a potassium channel antagonist (3,4-diaminopyridine; 3,4-DAP), can improve neuromuscular function in this mouse model. Bath application of GV-58 alone or in combination with 3,4-DAP significantly restored neuromuscular transmission to control levels in both a mildly vulnerable forearm muscle and a strongly vulnerable trunk muscle in SMNΔ7 mice at postnatal days 10-12. Similarly, acute subcutaneous administration of GV-58 to postnatal day 10 SMNΔ7 mice, alone or in combination with 3,4-DAP, significantly increased a behavioral measure of muscle strength. These data suggest that GV-58 may be a promising treatment candidate that could address deficits in neuromuscular function and strength and that the addition of 3,4-DAP to GV-58 treatment could aid in restoring function in SMA.
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Affiliation(s)
- Kristine S Ojala
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Cassandra J Kaufhold
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Mykenzie R Davey
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Donggyun Yang
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Mary Liang
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Yomna Badawi
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
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7
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O'Connor K, Spendiff S, Lochmüller H, Horvath R. Mitochondrial Mutations Can Alter Neuromuscular Transmission in Congenital Myasthenic Syndrome and Mitochondrial Disease. Int J Mol Sci 2023; 24:ijms24108505. [PMID: 37239850 DOI: 10.3390/ijms24108505] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/28/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of rare, neuromuscular disorders that usually present in childhood or infancy. While the phenotypic presentation of these disorders is diverse, the unifying feature is a pathomechanism that disrupts neuromuscular transmission. Recently, two mitochondrial genes-SLC25A1 and TEFM-have been reported in patients with suspected CMS, prompting a discussion about the role of mitochondria at the neuromuscular junction (NMJ). Mitochondrial disease and CMS can present with similar symptoms, and potentially one in four patients with mitochondrial myopathy exhibit NMJ defects. This review highlights research indicating the prominent roles of mitochondria at both the pre- and postsynapse, demonstrating the potential for mitochondrial involvement in neuromuscular transmission defects. We propose the establishment of a novel subcategorization for CMS-mitochondrial CMS, due to unifying clinical features and the potential for mitochondrial defects to impede transmission at the pre- and postsynapse. Finally, we highlight the potential of targeting the neuromuscular transmission in mitochondrial disease to improve patient outcomes.
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Affiliation(s)
- Kaela O'Connor
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Neuromuscular Disease, University of Ottawa Brain and Mind Research Institute, Ottawa, ON K1H 8M5, Canada
| | - Sally Spendiff
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center-University of Freiburg, 79104 Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Catalonia, Spain
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB3 0FD, UK
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8
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Tejero R, Alsakkal M, Hennlein L, Lopez-Cabello AM, Jablonka S, Tabares L. Nifedipine Ameliorates Cellular Differentiation Defects of Smn-Deficient Motor Neurons and Enhances Neuromuscular Transmission in SMA Mice. Int J Mol Sci 2023; 24:ijms24087648. [PMID: 37108811 PMCID: PMC10146780 DOI: 10.3390/ijms24087648] [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: 03/14/2023] [Revised: 04/11/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
In spinal muscular atrophy (SMA), mutations in or loss of the Survival Motor Neuron 1 (SMN1) gene reduce full-length SMN protein levels, which leads to the degeneration of a percentage of motor neurons. In mouse models of SMA, the development and maintenance of spinal motor neurons and the neuromuscular junction (NMJ) function are altered. Since nifedipine is known to be neuroprotective and increases neurotransmission in nerve terminals, we investigated its effects on cultured spinal cord motor neurons and motor nerve terminals of control and SMA mice. We found that application of nifedipine increased the frequency of spontaneous Ca2+ transients, growth cone size, cluster-like formations of Cav2.2 channels, and it normalized axon extension in SMA neurons in culture. At the NMJ, nifedipine significantly increased evoked and spontaneous release at low-frequency stimulation in both genotypes. High-strength stimulation revealed that nifedipine increased the size of the readily releasable pool (RRP) of vesicles in control but not SMA mice. These findings provide experimental evidence about the ability of nifedipine to prevent the appearance of developmental defects in SMA embryonic motor neurons in culture and reveal to which extent nifedipine could still increase neurotransmission at the NMJ in SMA mice under different functional demands.
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Affiliation(s)
- Rocio Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Mohammad Alsakkal
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Ana M Lopez-Cabello
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Lucia Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
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9
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Rey F, Berardo C, Maghraby E, Mauri A, Messa L, Esposito L, Casili G, Ottolenghi S, Bonaventura E, Cuzzocrea S, Zuccotti G, Tonduti D, Esposito E, Paterniti I, Cereda C, Carelli S. Redox Imbalance in Neurological Disorders in Adults and Children. Antioxidants (Basel) 2023; 12:antiox12040965. [PMID: 37107340 PMCID: PMC10135575 DOI: 10.3390/antiox12040965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/03/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Oxygen is a central molecule for numerous metabolic and cytophysiological processes, and, indeed, its imbalance can lead to numerous pathological consequences. In the human body, the brain is an aerobic organ and for this reason, it is very sensitive to oxygen equilibrium. The consequences of oxygen imbalance are especially devastating when occurring in this organ. Indeed, oxygen imbalance can lead to hypoxia, hyperoxia, protein misfolding, mitochondria dysfunction, alterations in heme metabolism and neuroinflammation. Consequently, these dysfunctions can cause numerous neurological alterations, both in the pediatric life and in the adult ages. These disorders share numerous common pathways, most of which are consequent to redox imbalance. In this review, we will focus on the dysfunctions present in neurodegenerative disorders (specifically Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis) and pediatric neurological disorders (X-adrenoleukodystrophies, spinal muscular atrophy, mucopolysaccharidoses and Pelizaeus-Merzbacher Disease), highlighting their underlining dysfunction in redox and identifying potential therapeutic strategies.
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Affiliation(s)
- Federica Rey
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Clarissa Berardo
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Erika Maghraby
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Alessia Mauri
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Letizia Messa
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
- Department of Electronics, Information and Bioengineering (DEIB), Politecnico di Milano, 20133 Milano, Italy
| | - Letizia Esposito
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Giovanna Casili
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Sara Ottolenghi
- Department of Medicine and Surgery, University of Milano Bicocca, 20126 Milano, Italy
| | - Eleonora Bonaventura
- Child Neurology Unit, Buzzi Children's Hospital, 20154 Milano, Italy
- Center for Diagnosis and Treatment of Leukodystrophies and Genetic Leukoencephalopathies (COALA), Buzzi Children's Hospital, 20154 Milano, Italy
| | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Gianvincenzo Zuccotti
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Davide Tonduti
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Child Neurology Unit, Buzzi Children's Hospital, 20154 Milano, Italy
- Center for Diagnosis and Treatment of Leukodystrophies and Genetic Leukoencephalopathies (COALA), Buzzi Children's Hospital, 20154 Milano, Italy
| | - Emanuela Esposito
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Irene Paterniti
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Cristina Cereda
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Stephana Carelli
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
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10
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Hennlein L, Ghanawi H, Gerstner F, Palominos García E, Yildirim E, Saal-Bauernschubert L, Moradi M, Deng C, Klein T, Appenzeller S, Sauer M, Briese M, Simon C, Sendtner M, Jablonka S. Plastin 3 rescues cell surface translocation and activation of TrkB in spinal muscular atrophy. J Cell Biol 2023; 222:e202204113. [PMID: 36607273 PMCID: PMC9827530 DOI: 10.1083/jcb.202204113] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 10/12/2022] [Accepted: 12/08/2022] [Indexed: 01/07/2023] Open
Abstract
Plastin 3 (PLS3) is an F-actin-bundling protein that has gained attention as a modifier of spinal muscular atrophy (SMA) pathology. SMA is a lethal pediatric neuromuscular disease caused by loss of or mutations in the Survival Motor Neuron 1 (SMN1) gene. Pathophysiological hallmarks are cellular maturation defects of motoneurons prior to degeneration. Despite the observed beneficial modifying effect of PLS3, the mechanism of how it supports F-actin-mediated cellular processes in motoneurons is not yet well understood. Our data reveal disturbed F-actin-dependent translocation of the Tropomyosin receptor kinase B (TrkB) to the cell surface of Smn-deficient motor axon terminals, resulting in reduced TrkB activation by its ligand brain-derived neurotrophic factor (BDNF). Improved actin dynamics by overexpression of hPLS3 restores membrane recruitment and activation of TrkB and enhances spontaneous calcium transients by increasing Cav2.1/2 "cluster-like" formations in SMA axon terminals. Thus, our study provides a novel role for PLS3 in supporting correct alignment of transmembrane proteins, a key mechanism for (moto)-neuronal development.
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Affiliation(s)
- Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Hanaa Ghanawi
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Florian Gerstner
- Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | | | - Ezgi Yildirim
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | | | - Mehri Moradi
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Chunchu Deng
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Teresa Klein
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Silke Appenzeller
- Comprehensive Cancer Center Mainfranken; Core Unit Bioinformatics, University Hospital Würzburg, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Christian Simon
- Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
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11
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Zilio E, Piano V, Wirth B. Mitochondrial Dysfunction in Spinal Muscular Atrophy. Int J Mol Sci 2022; 23:ijms231810878. [PMID: 36142791 PMCID: PMC9503857 DOI: 10.3390/ijms231810878] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by recessive mutations in the SMN1 gene, globally affecting ~8-14 newborns per 100,000. The severity of the disease depends on the residual levels of functional survival of motor neuron protein, SMN. SMN is a ubiquitously expressed RNA binding protein involved in a plethora of cellular processes. In this review, we discuss the effects of SMN loss on mitochondrial functions in the neuronal and muscular systems that are the most affected in patients with spinal muscular atrophy. Our aim is to highlight how mitochondrial defects may contribute to disease progression and how restoring mitochondrial functionality may be a promising approach to develop new therapies. We also collected from previous studies a list of transcripts encoding mitochondrial proteins affected in various SMA models. Moreover, we speculate that in adulthood, when motor neurons require only very low SMN levels, the natural deterioration of mitochondria associated with aging may be a crucial triggering factor for adult spinal muscular atrophy, and this requires particular attention for therapeutic strategies.
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Affiliation(s)
- Eleonora Zilio
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
| | - Valentina Piano
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence: (V.P.); (B.W.)
| | - Brunhilde Wirth
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence: (V.P.); (B.W.)
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12
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Kim JH, Kang JS, Yoo K, Jeong J, Park I, Park JH, Rhee J, Jeon S, Jo YW, Hann SH, Seo M, Moon S, Um SJ, Seong RH, Kong YY. Bap1/SMN axis in Dpp4+ skeletal muscle mesenchymal cells regulates the neuromuscular system. JCI Insight 2022; 7:158380. [PMID: 35603786 PMCID: PMC9220848 DOI: 10.1172/jci.insight.158380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/06/2022] [Indexed: 12/15/2022] Open
Abstract
The survival of motor neuron (SMN) protein is a major component of the pre-mRNA splicing machinery and is required for RNA metabolism. Although SMN has been considered a fundamental gene for the central nervous system, due to its relationship with neuromuscular diseases, such as spinal muscular atrophy, recent studies have also revealed the requirement of SMN in non-neuronal cells in the peripheral regions. Here, we report that the fibro-adipogenic progenitor subpopulation expressing Dpp4 (Dpp4+ FAPs) is required for the neuromuscular system. Furthermore, we also reveal that BRCA1-associated protein-1 (Bap1) is crucial for the stabilization of SMN in FAPs by preventing its ubiquitination-dependent degradation. Inactivation of Bap1 in FAPs decreased SMN levels and accompanied degeneration of the neuromuscular junction, leading to loss of motor neurons and muscle atrophy. Overexpression of the ubiquitination-resistant SMN variant, SMNK186R, in Bap1-null FAPs completely prevented neuromuscular degeneration. In addition, transplantation of Dpp4+ FAPs, but not Dpp4– FAPs, completely rescued neuromuscular defects. Our data reveal the crucial role of Bap1-mediated SMN stabilization in Dpp4+ FAPs for the neuromuscular system and provide the possibility of cell-based therapeutics to treat neuromuscular diseases.
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Affiliation(s)
- Ji-Hoon Kim
- School of Biological Sciences, Seoul National University, Seoul, South Korea
- Molecular Recognition Research Center, Korea Institute of Science and Technology, Seoul, South Korea
| | - Jong-Seol Kang
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Kyusang Yoo
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Jinguk Jeong
- School of Biological Sciences, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Inkuk Park
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Jong Ho Park
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Joonwoo Rhee
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Shin Jeon
- School of Biological Sciences, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Young-Woo Jo
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Sang-Hyeon Hann
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Minji Seo
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Seungtae Moon
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, South Korea
| | - Soo-Jong Um
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, South Korea
| | - Rho Hyun Seong
- School of Biological Sciences, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Young-Yun Kong
- School of Biological Sciences, Seoul National University, Seoul, South Korea
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13
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Lopez-Manzaneda M, Fuentes-Moliz A, Tabares L. Presynaptic Mitochondria Communicate With Release Sites for Spatio-Temporal Regulation of Exocytosis at the Motor Nerve Terminal. Front Synaptic Neurosci 2022; 14:858340. [PMID: 35645766 PMCID: PMC9133601 DOI: 10.3389/fnsyn.2022.858340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
Presynaptic Ca2+ regulation is critical for accurate neurotransmitter release, vesicle reloading of release sites, and plastic changes in response to electrical activity. One of the main players in the regulation of cytosolic Ca2+ in nerve terminals is mitochondria, which control the size and spread of the Ca2+ wave during sustained electrical activity. However, the role of mitochondria in Ca2+ signaling during high-frequency short bursts of action potentials (APs) is not well known. Here, we studied spatial and temporal relationships between mitochondrial Ca2+ (mCa2+) and exocytosis by live imaging and electrophysiology in adult motor nerve terminals of transgenic mice expressing synaptophysin-pHluorin (SypHy). Our results show that hot spots of exocytosis and mitochondria are organized in subsynaptic functional regions and that mitochondria start to uptake Ca2+ after a few APs. We also show that mitochondria contribute to the regulation of the mode of fusion (synchronous and asynchronous) and the kinetics of release and replenishment of the readily releasable pool (RRP) of vesicles. We propose that mitochondria modulate the timing and reliability of neurotransmission in motor nerve terminals during brief AP trains.
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14
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Özer PZ, Koyunoğlu D, Son ÇD, Yurter HE, Bora G. SMN loss dysregulates microtubule-associated proteins in spinal muscular atrophy model. Mol Cell Neurosci 2022; 120:103725. [DOI: 10.1016/j.mcn.2022.103725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 03/24/2022] [Accepted: 03/26/2022] [Indexed: 10/18/2022] Open
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15
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Welby E, Rehborg RJ, Harmelink M, Ebert AD. Assessment of cerebral spinal fluid biomarkers and microRNA-mediated disease mechanisms in spinal muscular atrophy patient samples. Hum Mol Genet 2021; 31:1830-1843. [PMID: 34919695 DOI: 10.1093/hmg/ddab365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/01/2021] [Accepted: 12/09/2021] [Indexed: 11/14/2022] Open
Abstract
Cerebral spinal fluid (CSF) is a promising biospecimen for the detection of central nervous system biomarkers to monitor therapeutic efficacy at the cellular level in neurological diseases. Spinal muscular atrophy (SMA) patients receiving intrathecal antisense oligonucleotide (nusinersen) therapy tend to show improved motor function, but the treatment effect on cellular health remains unknown. The objective of this study was to assess the potential of extracellular RNAs and microRNAs in SMA patient CSF as indicators of neuron and glial health following nusinersen treatment. Extracellular RNA analysis of CSF samples revealed ongoing cellular stress related to inflammation and glial differentiation, even after treatment administration. Downregulated microRNA expression associated with SMA-specific or general motor neuron dysfunction in animal and cellular models, tended to increase in nusinersen treated patient CSF samples and correlated with SMA Type 1 and 2 motor functioning improvements. However, miR-146a, known to be upregulated in SMA induced pluripotent stem cell (iPSC)-derived astrocytes, showed increased expression in nusinersen treated CSF samples. We then used mRNA sequencing and multi-electrode arrays to assess the transcriptional and functional effects of miR-146a on healthy and SMA iPSC-derived motor neurons. miR-146a treatment on iPSC-derived motor neurons led to a downregulation of extracellular matrix genes associated with synaptic perineuronal net and alterations in spontaneous electrophysiological activity. Together, this study suggests that extracellular RNAs and microRNAs may serve as useful biomarkers to monitor cellular health during nusinersen treatment. Moreover, these data highlight the importance of addressing astrocyte health and response to nusinersen in SMA pathogenesis and treatment strategies.
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Affiliation(s)
- Emily Welby
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Rebecca J Rehborg
- Department of Neurology (Child Neurology), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Matthew Harmelink
- Department of Neurology (Child Neurology), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
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16
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Di Paolo A, Garat J, Eastman G, Farias J, Dajas-Bailador F, Smircich P, Sotelo-Silveira JR. Functional Genomics of Axons and Synapses to Understand Neurodegenerative Diseases. Front Cell Neurosci 2021; 15:686722. [PMID: 34248504 PMCID: PMC8267896 DOI: 10.3389/fncel.2021.686722] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 06/02/2021] [Indexed: 01/02/2023] Open
Abstract
Functional genomics studies through transcriptomics, translatomics and proteomics have become increasingly important tools to understand the molecular basis of biological systems in the last decade. In most cases, when these approaches are applied to the nervous system, they are centered in cell bodies or somatodendritic compartments, as these are easier to isolate and, at least in vitro, contain most of the mRNA and proteins present in all neuronal compartments. However, key functional processes and many neuronal disorders are initiated by changes occurring far away from cell bodies, particularly in axons (axopathologies) and synapses (synaptopathies). Both neuronal compartments contain specific RNAs and proteins, which are known to vary depending on their anatomical distribution, developmental stage and function, and thus form the complex network of molecular pathways required for neuron connectivity. Modifications in these components due to metabolic, environmental, and/or genetic issues could trigger or exacerbate a neuronal disease. For this reason, detailed profiling and functional understanding of the precise changes in these compartments may thus yield new insights into the still intractable molecular basis of most neuronal disorders. In the case of synaptic dysfunctions or synaptopathies, they contribute to dozens of diseases in the human brain including neurodevelopmental (i.e., autism, Down syndrome, and epilepsy) as well as neurodegenerative disorders (i.e., Alzheimer's and Parkinson's diseases). Histological, biochemical, cellular, and general molecular biology techniques have been key in understanding these pathologies. Now, the growing number of omics approaches can add significant extra information at a high and wide resolution level and, used effectively, can lead to novel and insightful interpretations of the biological processes at play. This review describes current approaches that use transcriptomics, translatomics and proteomic related methods to analyze the axon and presynaptic elements, focusing on the relationship that axon and synapses have with neurodegenerative diseases.
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Affiliation(s)
- Andres Di Paolo
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Departamento de Proteínas y Ácidos Nucleicos, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Joaquin Garat
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Guillermo Eastman
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Joaquina Farias
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Polo de Desarrollo Universitario “Espacio de Biología Vegetal del Noreste”, Centro Universitario Regional Noreste, Universidad de la República (UdelaR), Tacuarembó, Uruguay
| | - Federico Dajas-Bailador
- School of Life Sciences, Medical School Building, University of Nottingham, Nottingham, United Kingdom
| | - Pablo Smircich
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Universidad de la República (UdelaR), Montevideo, Uruguay
| | - José Roberto Sotelo-Silveira
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República (UdelaR), Montevideo, Uruguay
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17
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Villarroel-Campos D, Schiavo G, Sleigh JN. Dissection, in vivo imaging and analysis of the mouse epitrochleoanconeus muscle. J Anat 2021; 241:1108-1119. [PMID: 34121181 PMCID: PMC9558155 DOI: 10.1111/joa.13478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 12/25/2022] Open
Abstract
Analysis of rodent muscles affords an opportunity to glean key insights into neuromuscular development and the detrimental impact of disease‐causing genetic mutations. Muscles of the distal leg, for instance the gastrocnemius and tibialis anterior, are commonly used in such studies with mice and rats. However, thin and flat muscles, which can be dissected, processed and imaged without major disruption to muscle fibres and nerve‐muscle contacts, are more suitable for accurate and detailed analyses of the peripheral motor nervous system. One such wholemount muscle is the predominantly fast twitch epitrochleoanconeus (ETA), which is located in the upper forelimb, innervated by the radial nerve, and contains relatively large and uniformly flat neuromuscular junctions (NMJs). To facilitate incorporation of the ETA into the experimental toolkit of the neuromuscular disease field, here, we describe a simple method for its rapid isolation (<5 min), supported by high‐resolution videos and step‐by‐step images. Furthermore, we outline how the ETA can be imaged in live, anaesthetised mice, to enable examination of dynamic cellular processes occurring at the NMJ and within intramuscular axons, including transport of organelles, such as mitochondria and signalling endosomes. Finally, we present reference data on wild‐type ETA fibre‐type composition in young adult, male C57BL6/J mice. Comparative neuroanatomical studies of different muscles in rodent models of disease can generate critical insights into pathogenesis and pathology; dissection of the wholemount ETA provides the possibility to diversify the repertoire of muscles analysed for this endeavour.
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Affiliation(s)
- David Villarroel-Campos
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
| | - James N Sleigh
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
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18
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Fulceri F, Biagioni F, Limanaqi F, Busceti CL, Ryskalin L, Lenzi P, Fornai F. Ultrastructural characterization of peripheral denervation in a mouse model of Type III spinal muscular atrophy. J Neural Transm (Vienna) 2021; 128:771-791. [PMID: 33999256 PMCID: PMC8205903 DOI: 10.1007/s00702-021-02353-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/10/2021] [Indexed: 01/02/2023]
Abstract
Spinal muscular atrophy (SMA) is a heritable, autosomal recessive neuromuscular disorder characterized by a loss of the survival of motor neurons (SMN) protein, which leads to degeneration of lower motor neurons, and muscle atrophy. Despite SMA being nosographically classified as a motor neuron disease, recent advances indicate that peripheral alterations at the level of the neuromuscular junction (NMJ), involving the muscle, and axons of the sensory-motor system, occur early, and may even precede motor neuron loss. In the present study, we used a mouse model of slow progressive (type III) SMA, whereby the absence of the mouse SMN protein is compensated by the expression of two human genes (heterozygous SMN1A2G, and SMN2). This leads to late disease onset and prolonged survival, which allows for dissecting slow degenerative steps operating early in SMA pathogenesis. In this purely morphological study carried out at transmission electron microscopy, we extend the examination of motor neurons and proximal axons towards peripheral components, including distal axons, muscle fibers, and also muscle spindles. We document remarkable ultrastructural alterations being consistent with early peripheral denervation in SMA, which may shift the ultimate anatomical target in neuromuscular disease from the spinal cord towards the muscle. This concerns mostly mitochondrial alterations within distal axons and muscle, which are quantified here through ultrastructural morphometry. The present study is expected to provide a deeper knowledge of early pathogenic mechanisms in SMA.
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Affiliation(s)
- Federica Fulceri
- Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | | | - Fiona Limanaqi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | - Carla L Busceti
- I.R.C.C.S. Neuromed, Via Atinense 18, 86077, Pozzilli, IS, Italy
| | - Larisa Ryskalin
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | - Paola Lenzi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | - Francesco Fornai
- I.R.C.C.S. Neuromed, Via Atinense 18, 86077, Pozzilli, IS, Italy. .,Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126, Pisa, Italy.
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19
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James R, Chaytow H, Ledahawsky LM, Gillingwater TH. Revisiting the role of mitochondria in spinal muscular atrophy. Cell Mol Life Sci 2021; 78:4785-4804. [PMID: 33821292 PMCID: PMC8195803 DOI: 10.1007/s00018-021-03819-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/22/2021] [Accepted: 03/23/2021] [Indexed: 02/07/2023]
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease of variable clinical severity that is caused by mutations in the survival motor neuron 1 (SMN1) gene. Despite its name, SMN is a ubiquitous protein that functions within and outside the nervous system and has multiple cellular roles in transcription, translation, and proteostatic mechanisms. Encouragingly, several SMN-directed therapies have recently reached the clinic, albeit this has highlighted the increasing need to develop combinatorial therapies for SMA to achieve full clinical efficacy. As a subcellular site of dysfunction in SMA, mitochondria represents a relevant target for a combinatorial therapy. Accordingly, we will discuss our current understanding of mitochondrial dysfunction in SMA, highlighting mitochondrial-based pathways that offer further mechanistic insights into the involvement of mitochondria in SMA. This may ultimately facilitate translational development of targeted mitochondrial therapies for SMA. Due to clinical and mechanistic overlaps, such strategies may also benefit other motor neuron diseases and related neurodegenerative disorders.
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Affiliation(s)
- Rachel James
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Helena Chaytow
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Leire M Ledahawsky
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK.
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK.
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20
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Lopez-Manzaneda M, Franco-Espin J, Tejero R, Cano R, Tabares L. Calcium is reduced in presynaptic mitochondria of motor nerve terminals during neurotransmission in SMA mice. Hum Mol Genet 2021; 30:629-643. [PMID: 33693569 PMCID: PMC8127408 DOI: 10.1093/hmg/ddab065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 01/17/2023] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive degenerative motor neuron disease characterized by symmetrical muscle weakness and atrophy of limb and trunk muscles being the most severe genetic disease in children. In SMA mouse models, motor nerve terminals display neurotransmitter release reduction, endocytosis decrease and mitochondria alterations. The relationship between these changes is, however, not well understood. In the present study, we investigated whether the endocytosis impairment could be related to the functional alteration of the presynaptic mitochondria during action potential (AP) firing. To this aim, we generated a Synaptophysin-pHluorin (SypHy) transgenic mouse, crossed it with Taiwanese SMA mice, and recorded exo- and endocytosis and mitochondria Ca2+ signaling in real-time at ex vivo motor nerve terminals of Taiwanese-SypHy mice. The experiments were performed at the beginning of the motor symptoms to get an integrated view of the nerve terminal’s functional state before degeneration. Our electrophysiological and live imaging results demonstrated that the mitochondria’s capacity to increase matrix-free Ca2+ in SMA mice was significantly limited during nerve AP firing, except when the rate of Ca2+ entry to the cytosol was considerably reduced. These results indicate that both the mitochondrial Ca2+ signaling alterations and the secretion machinery defects are significant players in the dysfunction of the presynaptic terminal in SMA.
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Affiliation(s)
- Mario Lopez-Manzaneda
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Julio Franco-Espin
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Rocio Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Raquel Cano
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Lucia Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
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21
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In Search of a Cure: The Development of Therapeutics to Alter the Progression of Spinal Muscular Atrophy. Brain Sci 2021; 11:brainsci11020194. [PMID: 33562482 PMCID: PMC7915832 DOI: 10.3390/brainsci11020194] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022] Open
Abstract
Until the recent development of disease-modifying therapeutics, spinal muscular atrophy (SMA) was considered a devastating neuromuscular disease with a poor prognosis for most affected individuals. Symptoms generally present during early childhood and manifest as muscle weakness and progressive paralysis, severely compromising the affected individual’s quality of life, independence, and lifespan. SMA is most commonly caused by the inheritance of homozygously deleted SMN1 alleles with retention of one or more copies of a paralog gene, SMN2, which inversely correlates with disease severity. The recent advent and use of genetically targeted therapies have transformed SMA into a prototype for monogenic disease treatment in the era of genetic medicine. Many SMA-affected individuals receiving these therapies achieve traditionally unobtainable motor milestones and survival rates as medicines drastically alter the natural progression of this disease. This review discusses historical SMA progression and underlying disease mechanisms, highlights advances made in therapeutic research, clinical trials, and FDA-approved medicines, and discusses possible second-generation and complementary medicines as well as optimal temporal intervention windows in order to optimize motor function and improve quality of life for all SMA-affected individuals.
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22
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Bora G, Hensel N, Rademacher S, Koyunoğlu D, Sunguroğlu M, Aksu-Mengeş E, Balcı-Hayta B, Claus P, Erdem-Yurter H. Microtubule-associated protein 1B dysregulates microtubule dynamics and neuronal mitochondrial transport in spinal muscular atrophy. Hum Mol Genet 2021; 29:3935-3944. [PMID: 33410474 DOI: 10.1093/hmg/ddaa275] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/21/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating childhood disease primarily affecting lower motoneurons in the spinal cord. SMA is caused by the loss of functional survival of motoneuron (SMN) protein, leading to structural and functional alterations of the cytoskeleton in motoneurons and other cells. Loss of SMN results in impairments of microtubule architecture, but the underlying mechanisms are not completely understood. In this study, we mechanistically analyzed the effects of SMN deficiency on microtubules, demonstrating a reduced stability together with a reduction in alpha tubulin detyrosination. This was caused by increased levels of microtubule-associated protein 1B and tubulin tyrosine ligase, resulting in mitochondrial mislocalization in SMA. Our findings suggest that altered tubulin post-translational modifications and microtubule-associated proteins are involved in the pathomechanisms of SMA, such as an impaired axonal transport of mitochondria.
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Affiliation(s)
- Gamze Bora
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Niko Hensel
- Institute of Neuroanatomy and Cell Biology, OE 4140, Hannover Medical School, Hannover 30625, Germany.,Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Sebastian Rademacher
- Institute of Neuroanatomy and Cell Biology, OE 4140, Hannover Medical School, Hannover 30625, Germany
| | - Dila Koyunoğlu
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Merve Sunguroğlu
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Evrim Aksu-Mengeş
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Burcu Balcı-Hayta
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Peter Claus
- Institute of Neuroanatomy and Cell Biology, OE 4140, Hannover Medical School, Hannover 30625, Germany.,Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Hayat Erdem-Yurter
- Department of Medical Biology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
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23
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Autophagy in motor neuron diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 172:157-202. [PMID: 32620242 DOI: 10.1016/bs.pmbts.2020.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Motor neuron diseases (MNDs) are a wide group of neurodegenerative disorders characterized by the degeneration of a specific neuronal type located in the central nervous system, the motor neuron (MN). There are two main types of MNs, spinal and cortical MNs and depending on the type of MND, one or both types are affected. Cortical MNs innervate spinal MNs and these control a variety of cellular targets, being skeletal muscle their main one which is also affected in MNDs. A correct functionality of autophagy is necessary for the survival of all cellular types and it is particularly crucial for neurons, given their postmitotic and highly specialized nature. Numerous studies have identified alterations of autophagy activity in multiple MNDs. The scientific community has been particularly prolific in reporting the role that autophagy plays in the most common adult MND, amyotrophic lateral sclerosis, although many studies have started to identify physiological and pathological functions of this catabolic system in other MNDs, such as spinal muscular atrophy and spinal and bulbar muscular atrophy. The degradation of selective cargo by autophagy and how this process is altered upon the presence of MND-causing mutations is currently also a matter of intense investigation, particularly regarding the selective autophagic clearance of mitochondria. Thorough reviews on this field have been recently published. This chapter will cover the current knowledge on the functionality of autophagy and lysosomal homeostasis in the main MNDs and other autophagy-related topics in the MND field that have risen special interest in the research community.
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24
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Tejero R, Balk S, Franco-Espin J, Ojeda J, Hennlein L, Drexl H, Dombert B, Clausen JD, Torres-Benito L, Saal-Bauernschubert L, Blum R, Briese M, Appenzeller S, Tabares L, Jablonka S. R-Roscovitine Improves Motoneuron Function in Mouse Models for Spinal Muscular Atrophy. iScience 2020; 23:100826. [PMID: 31981925 PMCID: PMC6992996 DOI: 10.1016/j.isci.2020.100826] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/08/2019] [Accepted: 01/06/2020] [Indexed: 12/27/2022] Open
Abstract
Neurotransmission defects and motoneuron degeneration are hallmarks of spinal muscular atrophy, a monogenetic disease caused by the deficiency of the SMN protein. In the present study, we show that systemic application of R-Roscovitine, a Cav2.1/Cav2.2 channel modifier and a cyclin-dependent kinase 5 (Cdk-5) inhibitor, significantly improved survival of SMA mice. In addition, R-Roscovitine increased Cav2.1 channel density and sizes of the motor endplates. In vitro, R-Roscovitine restored axon lengths and growth cone sizes of Smn-deficient motoneurons corresponding to enhanced spontaneous Ca2+ influx and elevated Cav2.2 channel cluster formations independent of its capability to inhibit Cdk-5. Acute application of R-Roscovitine at the neuromuscular junction significantly increased evoked neurotransmitter release, increased the frequency of spontaneous miniature potentials, and lowered the activation threshold of silent terminals. These data indicate that R-Roscovitine improves Ca2+ signaling and Ca2+ homeostasis in Smn-deficient motoneurons, which is generally crucial for motoneuron differentiation, maturation, and function. R-Roscovitine prolongs survival of SMA mice R-Roscovitine increases Ca2+ influx and growth cone size of SMA motoneurons R-Roscovitine beneficially affects neurotransmission in SMA motor nerve terminals R-Roscovitine wakes up dormant synapses of SMA motoneurons
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Affiliation(s)
- Rocio Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Stefanie Balk
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Julio Franco-Espin
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Jorge Ojeda
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Hans Drexl
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Benjamin Dombert
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Jan-Dierk Clausen
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Laura Torres-Benito
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | | | - Robert Blum
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Silke Appenzeller
- Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, 97080 Würzburg, Germany; Core Unit SysMed, University of Würzburg, 97080 Würzburg, Germany
| | - Lucia Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain.
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany.
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25
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Eshraghi M, Gombar R, De Repentigny Y, Vacratsis PO, Kothary R. Pathologic Alterations in the Proteome of Synaptosomes from a Mouse Model of Spinal Muscular Atrophy. J Proteome Res 2019; 18:3042-3051. [PMID: 31262178 DOI: 10.1021/acs.jproteome.9b00159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spinal muscular atrophy (SMA) is a human genetic disorder characterized by muscle weakness, muscle atrophy, and death of motor neurons. SMA is caused by mutations or deletions in a gene called survival motor neuron 1 (SMN1). SMN1 is a housekeeping gene, but the most prominent pathologies in SMA are atrophy of myofibers and death of motor neurons. Further, degeneration of neuromuscular junctions, of synapses, and of axonal regions are features of SMA disease. Here, we have investigated the proteome dynamics of central synapses in P14 Smn2B/- mice, a model of SMA. Label-free quantitative proteomics on isolated synaptosomes from spinal cords of these animals identified 2030 protein groups. Statistical data analysis revealed 65 specific alterations in the proteome of the central synapses at the early onset stage of disease. Functional analysis of the dysregulated proteins indicated a significant enrichment of proteins associated with mitochondrial dynamics, cholesterol biogenesis, and protein clearance. These pathways represent potential targets for therapy development with the goal of providing stability to the central synapses, thereby preserving neuronal integrity in the context of SMA disease. Data are available via ProteomeXchange with identifier PXD012850.
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Affiliation(s)
- Mehdi Eshraghi
- Regenerative Medicine Program , Ottawa Hospital Research Institute , Ottawa , Ontario K1H 8L6 , Canada.,University of Ottawa Centre for Neuromuscular Disease , Ottawa , Ontario K1H 8M5 , Canada
| | - Robert Gombar
- Department of Chemistry and Biochemistry , University of Windsor , Windsor , Ontario N9B 3P4 , Canada
| | - Yves De Repentigny
- Regenerative Medicine Program , Ottawa Hospital Research Institute , Ottawa , Ontario K1H 8L6 , Canada
| | - Panayiotis O Vacratsis
- Department of Chemistry and Biochemistry , University of Windsor , Windsor , Ontario N9B 3P4 , Canada
| | - Rashmi Kothary
- Regenerative Medicine Program , Ottawa Hospital Research Institute , Ottawa , Ontario K1H 8L6 , Canada.,University of Ottawa Centre for Neuromuscular Disease , Ottawa , Ontario K1H 8M5 , Canada
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26
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Gao X, Xu J, Chen H, Xue D, Pan W, Zhou C, Ma YC, Ma L. Defective Expression of Mitochondrial, Vacuolar H +-ATPase and Histone Genes in a C. elegans Model of SMA. Front Genet 2019; 10:410. [PMID: 31130987 PMCID: PMC6509145 DOI: 10.3389/fgene.2019.00410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 04/15/2019] [Indexed: 12/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a severe motor neuron degenerative disease caused by loss-of-function mutations in the survival motor neuron gene SMN1. It is widely posited that defective gene expression underlies SMA. However, the identities of these affected genes remain to be elucidated. By analyzing the transcriptome of a Caenorhabditis elegans SMA model at the pre-symptomatic stage, we found that the expression of numerous nuclear encoded mitochondrial genes and vacuolar H+-ATPase genes was significantly down-regulated, while that of histone genes was significantly up-regulated. We previously showed that the uaf-1 gene, encoding key splicing factor U2AF large subunit, could affect the behavior and lifespan of smn-1 mutants. Here, we found that smn-1 and uaf-1 interact to affect the recognition of 3′ and 5′ splice sites in a gene-specific manner. Altogether, our results suggest a functional interaction between smn-1 and uaf-1 in affecting RNA splicing and a potential effect of smn-1 on the expression of mitochondrial and histone genes.
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Affiliation(s)
- Xiaoyang Gao
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Jing Xu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Hao Chen
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Dingwu Xue
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Wenju Pan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Chuanman Zhou
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Yongchao C Ma
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States
| | - Long Ma
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
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27
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Jha NN, Kim JK, Monani UR. Motor neuron biology and disease: A current perspective on infantile-onset spinal muscular atrophy. FUTURE NEUROLOGY 2018; 13:161-172. [PMID: 31396020 DOI: 10.2217/fnl-2018-0008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Infantile-onset spinal muscular atrophy (SMA) is a prototypical disease in which to investigate selective neurodegenerative phenotypes. Caused by low levels of the ubiquitously expressed Survival Motor Neuron (SMN) protein, the disease mainly targets the spinal motor neurons. This selective phenotype remains largely unexplained, but has not hindered the development of SMN repletion as a means to a treatment. Here we chronicle recent advances in the area of SMA biology. We provide a brief background to the disease, highlight major advances that have shaped our current understanding of SMA, trace efforts to treat the condition, discuss the outcome of two promising new therapies and conclude by considering contemporary as well as new challenges stemming from recent successes within the field.
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Affiliation(s)
- Narendra N Jha
- Department of Pathology & Cell Biology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Center for Motor Neuron Biology & Disease, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032
| | - Jeong-Ki Kim
- Department of Pathology & Cell Biology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Center for Motor Neuron Biology & Disease, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032
| | - Umrao R Monani
- Department of Pathology & Cell Biology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Department of Neurology, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032.,Center for Motor Neuron Biology & Disease, 630 W. 168 St., Columbia University Medical Center, New York, NY 10032
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28
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Pletto D, Capra S, Finardi A, Colciaghi F, Nobili P, Battaglia GS, Locatelli D, Cagnoli C. Axon outgrowth and neuronal differentiation defects after a-SMN and FL-SMN silencing in primary hippocampal cultures. PLoS One 2018; 13:e0199105. [PMID: 29902268 PMCID: PMC6001960 DOI: 10.1371/journal.pone.0199105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 05/31/2018] [Indexed: 12/30/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is a severe autosomal recessive disease characterized by selective motor neuron degeneration, caused by disruptions of the Survival of Motor Neuron 1 (Smn1) gene. The main product of SMN1 is the full-length SMN protein (FL-SMN), that plays an established role in mRNA splicing. FL-SMN is also involved in neurite outgrowth and axonal transport. A shorter SMN isoform, axonal-SMN or a-SMN, displays a more specific axonal localization and has remarkable axonogenic properties in NSC-34. Introduction of known SMA mutations into the a-SMN transcript leads to impairment of axon growth and morphological defects similar to those observed in SMA patients and animal models. Although there is increasing evidence for the relevance of SMN axonal functions in SMA pathogenesis, the specific contributions of FL-SMN and a-SMN are not known yet. This work aimed to analyze the differential roles of FL-SMN and a-SMN in axon outgrowth and in neuronal homeostasis during differentiation of neurons into a mature phenotype. We employed primary cultures of hippocampal neurons as a well-defined model of polarization and differentiation. By analyzing subcellular localization, we showed that a-SMN is preferentially localized in the growing axonal compartment. By specifically silencing FL-SMN or a-SMN proteins, we demonstrated that both proteins play a role in axon growth, as their selective down-regulation reduces axon length without affecting dendritic arborization. a-SMN silencing, and in minor extent FL-SMN silencing, resulted in the growth of multi-neuritic neurons, impaired in the differentiation process of selecting a single axon out of multiple neurites. In these neurons, neurites often display mixed axonal and dendritic markers and abnormal distribution of the axonal initial segment protein Ankirin G, suggesting loss of neuronal polarity. Our results indicate that a-SMN and FL-SMN are needed for neuronal polarization and organization of axonal and dendritic compartments, processes that are fundamental for neuronal function and survival.
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Affiliation(s)
- Daniela Pletto
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Silvia Capra
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Adele Finardi
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Francesca Colciaghi
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Paola Nobili
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Giorgio Stefano Battaglia
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Denise Locatelli
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
| | - Cinzia Cagnoli
- Molecular Neuroanatomy and Pathogenesis Unit, Neurology VII—Clinical and Experimental Epileptology Unit, Foundation IRCCS Neurological Institute “C. Besta”, Milano, Italy
- * E-mail:
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29
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Tejero R, Lopez-Manzaneda M, Arumugam S, Tabares L. Synaptotagmin-2, and -1, linked to neurotransmission impairment and vulnerability in Spinal Muscular Atrophy. Hum Mol Genet 2018; 25:4703-4716. [PMID: 28173138 DOI: 10.1093/hmg/ddw297] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 01/19/2023] Open
Abstract
Spinal muscular atrophy (SMA) is the most frequent genetic cause of infant mortality. The disease is characterized by progressive muscle weakness and paralysis of axial and proximal limb muscles. It is caused by homozygous loss or mutation of the SMN1 gene, which codes for the Survival Motor Neuron (SMN) protein. In mouse models of the disease, neurotransmitter release is greatly impaired, but the molecular mechanisms of the synaptic dysfunction and the basis of the selective muscle vulnerability are unknown. In the present study, we investigated these open questions by comparing the molecular and functional properties of nerve terminals in severely and mildly affected muscles in the SMNΔ7 mouse model. We discovered that synaptotagmin-1 (Syt1) was developmentally downregulated in nerve terminals of highly affected muscles but not in low vulnerable muscles. Additionally, the expression levels of synaptotagmin-2 (Syt2), and its interacting protein, synaptic vesicle protein 2 (SV2) B, were reduced in proportion to the degree of muscle vulnerability while other synaptic proteins, such as syntaxin-1B (Stx1B) and synaptotagmin-7 (Syt7), were not affected. Consistently with the extremely low levels of both Syt-isoforms, and SV2B, in most affected neuromuscular synapses, the functional analysis of neurotransmission revealed highly reduced evoked release, altered short-term plasticity, low release probability, and inability to modulate normally the number of functional release sites. Together, we propose that the strong reduction of Syt2 and SV2B are key factors of the functional synaptic alteration and that the physiological downregulation of Syt1 plays a determinant role in muscle vulnerability in SMA.
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Affiliation(s)
- Rocío Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Avda. Sánchez Pizjuán, 4. 41009 Seville, Spain
| | - Mario Lopez-Manzaneda
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Avda. Sánchez Pizjuán, 4. 41009 Seville, Spain
| | - Saravanan Arumugam
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Avda. Sánchez Pizjuán, 4. 41009 Seville, Spain
| | - Lucía Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Avda. Sánchez Pizjuán, 4. 41009 Seville, Spain
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30
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Boido M, De Amicis E, Valsecchi V, Trevisan M, Ala U, Ruegg MA, Hettwer S, Vercelli A. Increasing Agrin Function Antagonizes Muscle Atrophy and Motor Impairment in Spinal Muscular Atrophy. Front Cell Neurosci 2018; 12:17. [PMID: 29440993 PMCID: PMC5797594 DOI: 10.3389/fncel.2018.00017] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/11/2018] [Indexed: 11/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a pediatric genetic disease, characterized by motor neuron (MN) death, leading to progressive muscle weakness, respiratory failure, and, in the most severe cases, to death. Abnormalities at the neuromuscular junction (NMJ) have been reported in SMA, including neurofilament (NF) accumulation at presynaptic terminals, immature and smaller than normal endplates, reduced transmitter release, and, finally, muscle denervation. Here we have studied the role of agrin in SMAΔ7 mice, the experimental model of SMAII. We observed a 50% reduction in agrin expression levels in quadriceps of P10 SMA mice compared to age-matched WT controls. To counteract such condition, we treated SMA mice from birth onwards with therapeutic agrin biological NT-1654, an active splice variant of agrin retaining synaptogenic properties, which is also resistant to proteolytic cleavage by neurotrypsin. Mice were analyzed for behavior, muscle and NMJ histology, and survival. Motor behavior was significantly improved and survival was extended by treatment of SMA mice with NT-1654. At P10, H/E-stained sections of the quadriceps, a proximal muscle early involved in SMA, showed that NT-1654 treatment strongly prevented the size decrease of muscle fibers. Studies of NMJ morphology on whole-mount diaphragm preparations revealed that NT-1654-treated SMA mice had more mature NMJs and reduced NF accumulation, compared to vehicle-treated SMA mice. We conclude that increasing agrin function in SMA has beneficial outcomes on muscle fibers and NMJs as the agrin biological NT-1654 restores the crosstalk between muscle and MNs, delaying muscular atrophy, improving motor performance and extending survival.
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Affiliation(s)
- Marina Boido
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
| | - Elena De Amicis
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
| | - Valeria Valsecchi
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
| | - Marco Trevisan
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
| | - Ugo Ala
- Department of Molecular Biotechnology and Health Sciences, University of Turin, Turin, Italy
| | | | | | - Alessandro Vercelli
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy.,Department of Neuroscience Rita Levi Montalcini, National Institute of Neuroscience, Turin, Italy
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31
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Dombert B, Balk S, Lüningschrör P, Moradi M, Sivadasan R, Saal-Bauernschubert L, Jablonka S. BDNF/trkB Induction of Calcium Transients through Ca v2.2 Calcium Channels in Motoneurons Corresponds to F-actin Assembly and Growth Cone Formation on β2-Chain Laminin (221). Front Mol Neurosci 2017; 10:346. [PMID: 29163025 PMCID: PMC5670157 DOI: 10.3389/fnmol.2017.00346] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/12/2017] [Indexed: 12/11/2022] Open
Abstract
Spontaneous Ca2+ transients and actin dynamics in primary motoneurons correspond to cellular differentiation such as axon elongation and growth cone formation. Brain-derived neurotrophic factor (BDNF) and its receptor trkB support both motoneuron survival and synaptic differentiation. However, in motoneurons effects of BDNF/trkB signaling on spontaneous Ca2+ influx and actin dynamics at axonal growth cones are not fully unraveled. In our study we addressed the question how neurotrophic factor signaling corresponds to cell autonomous excitability and growth cone formation. Primary motoneurons from mouse embryos were cultured on the synapse specific, β2-chain containing laminin isoform (221) regulating axon elongation through spontaneous Ca2+ transients that are in turn induced by enhanced clustering of N-type specific voltage-gated Ca2+ channels (Cav2.2) in axonal growth cones. TrkB-deficient (trkBTK-/-) mouse motoneurons which express no full-length trkB receptor and wildtype motoneurons cultured without BDNF exhibited reduced spontaneous Ca2+ transients that corresponded to altered axon elongation and defects in growth cone morphology which was accompanied by changes in the local actin cytoskeleton. Vice versa, the acute application of BDNF resulted in the induction of spontaneous Ca2+ transients and Cav2.2 clustering in motor growth cones, as well as the activation of trkB downstream signaling cascades which promoted the stabilization of β-actin via the LIM kinase pathway and phosphorylation of profilin at Tyr129. Finally, we identified a mutual regulation of neuronal excitability and actin dynamics in axonal growth cones of embryonic motoneurons cultured on laminin-221/211. Impaired excitability resulted in dysregulated axon extension and local actin cytoskeleton, whereas upon β-actin knockdown Cav2.2 clustering was affected. We conclude from our data that in embryonic motoneurons BDNF/trkB signaling contributes to axon elongation and growth cone formation through changes in the local actin cytoskeleton accompanied by increased Cav2.2 clustering and local calcium transients. These findings may help to explore cellular mechanisms which might be dysregulated during maturation of embryonic motoneurons leading to motoneuron disease.
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Affiliation(s)
- Benjamin Dombert
- Institute of Clinical Neurobiology, University of Wuerzburg, Wuerzburg, Germany
| | - Stefanie Balk
- Institute of Clinical Neurobiology, University of Wuerzburg, Wuerzburg, Germany
| | | | - Mehri Moradi
- Institute of Clinical Neurobiology, University of Wuerzburg, Wuerzburg, Germany
| | - Rajeeve Sivadasan
- Institute of Clinical Neurobiology, University of Wuerzburg, Wuerzburg, Germany
| | | | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University of Wuerzburg, Wuerzburg, Germany
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32
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Arumugam S, Garcera A, Soler RM, Tabares L. Smn-Deficiency Increases the Intrinsic Excitability of Motoneurons. Front Cell Neurosci 2017; 11:269. [PMID: 28928636 PMCID: PMC5591959 DOI: 10.3389/fncel.2017.00269] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/21/2017] [Indexed: 12/13/2022] Open
Abstract
During development, motoneurons experience significant changes in their size and in the number and strength of connections that they receive, which requires adaptive changes in their passive and active electrical properties. Even after reaching maturity, motoneurons continue to adjust their intrinsic excitability and synaptic activity for proper functioning of the sensorimotor circuit in accordance with physiological demands. Likewise, if some elements of the circuit become dysfunctional, the system tries to compensate for the alterations to maintain appropriate function. In Spinal Muscular Atrophy (SMA), a severe motor disease, spinal motoneurons receive less excitation from glutamatergic sensory fibers and interneurons and are electrically hyperexcitable. Currently, the origin and relationship among these alterations are not completely established. In this study, we investigated whether Survival of Motor Neuron (SMN), the ubiquitous protein defective in SMA, regulates the excitability of motoneurons before and after the establishment of the synaptic contacts. To this end, we performed patch-clamp recordings in embryonic spinal motoneurons forming complex synaptic networks in primary cultures, and in differentiated NSC-34 motoneuron-like cells in the absence of synaptic contacts. Our results show that in both conditions, Smn-deficient cells displayed lower action potential threshold, greater action potential amplitudes, and larger density of voltage-dependent sodium currents than cells with normal Smn-levels. These results indicate that Smn participates in the regulation of the cell-autonomous excitability of motoneurons at an early stage of development. This finding may contribute to a better understanding of motoneuron excitability in SMA during the development of the disease.
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Affiliation(s)
- Saravanan Arumugam
- Department of Medical Physiology and Biophysics, School of Medicine University of SevilleSeville, Spain
| | - Ana Garcera
- Unitat de Senyalització Neuronal, Departament de Medicina Experimental, Universitat de Lleida-IRBLLEIDALleida, Spain
| | - Rosa M Soler
- Unitat de Senyalització Neuronal, Departament de Medicina Experimental, Universitat de Lleida-IRBLLEIDALleida, Spain
| | - Lucía Tabares
- Department of Medical Physiology and Biophysics, School of Medicine University of SevilleSeville, Spain
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33
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Jablonka S, Sendtner M. Developmental regulation of SMN expression: pathophysiological implications and perspectives for therapy development in spinal muscular atrophy. Gene Ther 2017; 24:506-513. [DOI: 10.1038/gt.2017.46] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/16/2017] [Accepted: 05/19/2017] [Indexed: 12/18/2022]
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34
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Hensel N, Claus P. The Actin Cytoskeleton in SMA and ALS: How Does It Contribute to Motoneuron Degeneration? Neuroscientist 2017; 24:54-72. [PMID: 28459188 DOI: 10.1177/1073858417705059] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are neurodegenerative diseases with overlapping clinical phenotypes based on impaired motoneuron function. However, the pathomechanisms of both diseases are largely unknown, and it is still unclear whether they converge on the molecular level. SMA is a monogenic disease caused by low levels of functional Survival of Motoneuron (SMN) protein, whereas ALS involves multiple genes as well as environmental factors. Recent evidence argues for involvement of actin regulation as a causative and dysregulated process in both diseases. ALS-causing mutations in the actin-binding protein profilin-1 as well as the ability of the SMN protein to directly bind to profilins argue in favor of a common molecular mechanism involving the actin cytoskeleton. Profilins are major regulat ors of actin-dynamics being involved in multiple neuronal motility and transport processes as well as modulation of synaptic functions that are impaired in models of both motoneuron diseases. In this article, we review the current literature in SMA and ALS research with a focus on the actin cytoskeleton. We propose a common molecular mechanism that explains the degeneration of motoneurons for SMA and some cases of ALS.
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Affiliation(s)
- Niko Hensel
- 1 Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,2 Niedersachsen Network on Neuroinfectiology (N-RENNT), Hannover, Germany
| | - Peter Claus
- 1 Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,2 Niedersachsen Network on Neuroinfectiology (N-RENNT), Hannover, Germany.,3 Center for Systems Neuroscience (ZSN), Hannover, Germany
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35
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Singh RN, Howell MD, Ottesen EW, Singh NN. Diverse role of survival motor neuron protein. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2017; 1860:299-315. [PMID: 28095296 PMCID: PMC5325804 DOI: 10.1016/j.bbagrm.2016.12.008] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 12/23/2016] [Accepted: 12/30/2016] [Indexed: 02/07/2023]
Abstract
The multifunctional Survival Motor Neuron (SMN) protein is required for the survival of all organisms of the animal kingdom. SMN impacts various aspects of RNA metabolism through the formation and/or interaction with ribonucleoprotein (RNP) complexes. SMN regulates biogenesis of small nuclear RNPs, small nucleolar RNPs, small Cajal body-associated RNPs, signal recognition particles and telomerase. SMN also plays an important role in DNA repair, transcription, pre-mRNA splicing, histone mRNA processing, translation, selenoprotein synthesis, macromolecular trafficking, stress granule formation, cell signaling and cytoskeleton maintenance. The tissue-specific requirement of SMN is dictated by the variety and the abundance of its interacting partners. Reduced expression of SMN causes spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. SMA displays a broad spectrum ranging from embryonic lethality to an adult onset. Aberrant expression and/or localization of SMN has also been associated with male infertility, inclusion body myositis, amyotrophic lateral sclerosis and osteoarthritis. This review provides a summary of various SMN functions with implications to a better understanding of SMA and other pathological conditions.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
| | - Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
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Cappello V, Marchetti L, Parlanti P, Landi S, Tonazzini I, Cecchini M, Piazza V, Gemmi M. Ultrastructural Characterization of the Lower Motor System in a Mouse Model of Krabbe Disease. Sci Rep 2016; 6:1. [PMID: 28442746 PMCID: PMC5431369 DOI: 10.1038/s41598-016-0001-8] [Citation(s) in RCA: 6287] [Impact Index Per Article: 785.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 08/15/2016] [Indexed: 02/08/2023] Open
Abstract
Krabbe disease (KD) is a neurodegenerative disorder caused by the lack of β- galactosylceramidase enzymatic activity and by widespread accumulation of the cytotoxic galactosyl-sphingosine in neuronal, myelinating and endothelial cells. Despite the wide use of Twitcher mice as experimental model for KD, the ultrastructure of this model is partial and mainly addressing peripheral nerves. More details are requested to elucidate the basis of the motor defects, which are the first to appear during KD onset. Here we use transmission electron microscopy (TEM) to focus on the alterations produced by KD in the lower motor system at postnatal day 15 (P15), a nearly asymptomatic stage, and in the juvenile P30 mouse. We find mild effects on motorneuron soma, severe ones on sciatic nerves and very severe effects on nerve terminals and neuromuscular junctions at P30, with peripheral damage being already detectable at P15. Finally, we find that the gastrocnemius muscle undergoes atrophy and structural changes that are independent of denervation at P15. Our data further characterize the ultrastructural analysis of the KD mouse model, and support recent theories of a dying-back mechanism for neuronal degeneration, which is independent of demyelination.
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Affiliation(s)
- Valentina Cappello
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia Piazza San Silvestro, 12, 56127, Pisa, Italy.
| | - Laura Marchetti
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia Piazza San Silvestro, 12, 56127, Pisa, Italy
| | - Paola Parlanti
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia Piazza San Silvestro, 12, 56127, Pisa, Italy
- NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Silvia Landi
- NEST, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Ilaria Tonazzini
- NEST, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy
- Fondazione Umberto Veronesi, Piazza Velasca 5, 20122, Milano, Italy
| | - Marco Cecchini
- NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
- NEST, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Vincenzo Piazza
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia Piazza San Silvestro, 12, 56127, Pisa, Italy
| | - Mauro Gemmi
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia Piazza San Silvestro, 12, 56127, Pisa, Italy
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Hosseinibarkooie S, Peters M, Torres-Benito L, Rastetter R, Hupperich K, Hoffmann A, Mendoza-Ferreira N, Kaczmarek A, Janzen E, Milbradt J, Lamkemeyer T, Rigo F, Bennett C, Guschlbauer C, Büschges A, Hammerschmidt M, Riessland M, Kye M, Clemen C, Wirth B. The Power of Human Protective Modifiers: PLS3 and CORO1C Unravel Impaired Endocytosis in Spinal Muscular Atrophy and Rescue SMA Phenotype. Am J Hum Genet 2016; 99:647-665. [PMID: 27499521 DOI: 10.1016/j.ajhg.2016.07.014] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/14/2016] [Indexed: 12/13/2022] Open
Abstract
Homozygous loss of SMN1 causes spinal muscular atrophy (SMA), the most common and devastating childhood genetic motor-neuron disease. The copy gene SMN2 produces only ∼10% functional SMN protein, insufficient to counteract development of SMA. In contrast, the human genetic modifier plastin 3 (PLS3), an actin-binding and -bundling protein, fully protects against SMA in SMN1-deleted individuals carrying 3-4 SMN2 copies. Here, we demonstrate that the combinatorial effect of suboptimal SMN antisense oligonucleotide treatment and PLS3 overexpression-a situation resembling the human condition in asymptomatic SMN1-deleted individuals-rescues survival (from 14 to >250 days) and motoric abilities in a severe SMA mouse model. Because PLS3 knockout in yeast impairs endocytosis, we hypothesized that disturbed endocytosis might be a key cellular mechanism underlying impaired neurotransmission and neuromuscular junction maintenance in SMA. Indeed, SMN deficit dramatically reduced endocytosis, which was restored to normal levels by PLS3 overexpression. Upon low-frequency electro-stimulation, endocytotic FM1-43 (SynaptoGreen) uptake in the presynaptic terminal of neuromuscular junctions was restored to control levels in SMA-PLS3 mice. Moreover, proteomics and biochemical analysis revealed CORO1C, another F-actin binding protein, whose direct binding to PLS3 is dependent on calcium. Similar to PLS3 overexpression, CORO1C overexpression restored fluid-phase endocytosis in SMN-knockdown cells by elevating F-actin amounts and rescued the axonal truncation and branching phenotype in Smn-depleted zebrafish. Our findings emphasize the power of genetic modifiers to unravel the cellular pathomechanisms underlying SMA and the power of combinatorial therapy based on splice correction of SMN2 and endocytosis improvement to efficiently treat SMA.
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Dimitriadi M, Derdowski A, Kalloo G, Maginnis MS, O'Hern P, Bliska B, Sorkaç A, Nguyen KCQ, Cook SJ, Poulogiannis G, Atwood WJ, Hall DH, Hart AC. Decreased function of survival motor neuron protein impairs endocytic pathways. Proc Natl Acad Sci U S A 2016; 113:E4377-86. [PMID: 27402754 PMCID: PMC4968725 DOI: 10.1073/pnas.1600015113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by depletion of the ubiquitously expressed survival motor neuron (SMN) protein, with 1 in 40 Caucasians being heterozygous for a disease allele. SMN is critical for the assembly of numerous ribonucleoprotein complexes, yet it is still unclear how reduced SMN levels affect motor neuron function. Here, we examined the impact of SMN depletion in Caenorhabditis elegans and found that decreased function of the SMN ortholog SMN-1 perturbed endocytic pathways at motor neuron synapses and in other tissues. Diminished SMN-1 levels caused defects in C. elegans neuromuscular function, and smn-1 genetic interactions were consistent with an endocytic defect. Changes were observed in synaptic endocytic proteins when SMN-1 levels decreased. At the ultrastructural level, defects were observed in endosomal compartments, including significantly fewer docked synaptic vesicles. Finally, endocytosis-dependent infection by JC polyomavirus (JCPyV) was reduced in human cells with decreased SMN levels. Collectively, these results demonstrate for the first time, to our knowledge, that SMN depletion causes defects in endosomal trafficking that impair synaptic function, even in the absence of motor neuron cell death.
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Affiliation(s)
- Maria Dimitriadi
- Department of Neuroscience, Brown University, Providence, RI 02912; Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield AL10 9AB, United Kingdom
| | - Aaron Derdowski
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912
| | - Geetika Kalloo
- Department of Neuroscience, Brown University, Providence, RI 02912
| | - Melissa S Maginnis
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912; Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469
| | - Patrick O'Hern
- Department of Neuroscience, Brown University, Providence, RI 02912
| | - Bryn Bliska
- Department of Neuroscience, Brown University, Providence, RI 02912
| | - Altar Sorkaç
- Department of Neuroscience, Brown University, Providence, RI 02912
| | - Ken C Q Nguyen
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Steven J Cook
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - George Poulogiannis
- Chester Beatty Labs, The Institute of Cancer Research, London SW3 6JB, United Kingdom
| | - Walter J Atwood
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912
| | - David H Hall
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Anne C Hart
- Department of Neuroscience, Brown University, Providence, RI 02912;
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Bodaleo FJ, Gonzalez-Billault C. The Presynaptic Microtubule Cytoskeleton in Physiological and Pathological Conditions: Lessons from Drosophila Fragile X Syndrome and Hereditary Spastic Paraplegias. Front Mol Neurosci 2016; 9:60. [PMID: 27504085 PMCID: PMC4958632 DOI: 10.3389/fnmol.2016.00060] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/11/2016] [Indexed: 11/21/2022] Open
Abstract
The capacity of the nervous system to generate neuronal networks relies on the establishment and maintenance of synaptic contacts. Synapses are composed of functionally different presynaptic and postsynaptic compartments. An appropriate synaptic architecture is required to provide the structural basis that supports synaptic transmission, a process involving changes in cytoskeletal dynamics. Actin microfilaments are the main cytoskeletal components present at both presynaptic and postsynaptic terminals in glutamatergic synapses. However, in the last few years it has been demonstrated that microtubules (MTs) transiently invade dendritic spines, promoting their maturation. Nevertheless, the presence and functions of MTs at the presynaptic site are still a matter of debate. Early electron microscopy (EM) studies revealed that MTs are present in the presynaptic terminals of the central nervous system (CNS) where they interact with synaptic vesicles (SVs) and reach the active zone. These observations have been reproduced by several EM protocols; however, there is empirical heterogeneity in detecting presynaptic MTs, since they appear to be both labile and unstable. Moreover, increasing evidence derived from studies in the fruit fly neuromuscular junction proposes different roles for MTs in regulating presynaptic function in physiological and pathological conditions. In this review, we summarize the main findings that support the presence and roles of MTs at presynaptic terminals, integrating descriptive and biochemical analyses, and studies performed in invertebrate genetic models.
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Affiliation(s)
- Felipe J Bodaleo
- Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de ChileSantiago, Chile; Center for Geroscience, Brain Health and Metabolism (GERO)Santiago, Chile
| | - Christian Gonzalez-Billault
- Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de ChileSantiago, Chile; Center for Geroscience, Brain Health and Metabolism (GERO)Santiago, Chile; The Buck Institute for Research on Aging, NovatoCA, USA
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40
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Neve A, Trüb J, Saxena S, Schümperli D. Central and peripheral defects in motor units of the diaphragm of spinal muscular atrophy mice. Mol Cell Neurosci 2016; 70:30-41. [PMID: 26621405 DOI: 10.1016/j.mcn.2015.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 10/30/2015] [Accepted: 11/23/2015] [Indexed: 01/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is characterized by motoneuron loss and muscle weakness. However, the structural and functional deficits that lead to the impairment of the neuromuscular system remain poorly defined. By electron microscopy, we previously found that neuromuscular junctions (NMJs) and muscle fibres of the diaphragm are among the earliest affected structures in the severe mouse SMA model. Because of certain anatomical features, i.e. its thinness and its innervation from the cervical segments of the spinal cord, the diaphragm is particularly suitable to characterize both central and peripheral events. Here we show by immunohistochemistry that, at postnatal day 3, the cervical motoneurons of SMA mice receive less stimulatory synaptic inputs. Moreover, their mitochondria become less elongated which might represent an early stage of degeneration. The NMJs of the diaphragm of SMA mice show a loss of synaptic vesicles and active zones. Moreover, the partly innervated endplates lack S100 positive perisynaptic Schwann cells (PSCs). We also demonstrate the feasibility of comparing the proteomic composition between diaphragm regions enriched and poor in NMJs. By this approach we have identified two proteins that are significantly upregulated only in the NMJ-specific regions of SMA mice. These are apoptosis inducing factor 1 (AIFM1), a mitochondrial flavoprotein that initiates apoptosis in a caspase-independent pathway, and four and a half Lim domain protein 1 (FHL1), a regulator of skeletal muscle mass that has been implicated in several myopathies.
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Affiliation(s)
- Anuja Neve
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Judith Trüb
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| | - Smita Saxena
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| | - Daniel Schümperli
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland.
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41
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orthoFind Facilitates the Discovery of Homologous and Orthologous Proteins. PLoS One 2015; 10:e0143906. [PMID: 26624019 PMCID: PMC4666658 DOI: 10.1371/journal.pone.0143906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/07/2015] [Indexed: 11/19/2022] Open
Abstract
Finding homologous and orthologous protein sequences is often the first step in evolutionary studies, annotation projects, and experiments of functional complementation. Despite all currently available computational tools, there is a requirement for easy-to-use tools that provide functional information. Here, a new web application called orthoFind is presented, which allows a quick search for homologous and orthologous proteins given one or more query sequences, allowing a recurrent and exhaustive search against reference proteomes, and being able to include user databases. It addresses the protein multidomain problem, searching for homologs with the same domain architecture, and gives a simple functional analysis of the results to help in the annotation process. orthoFind is easy to use and has been proven to provide accurate results with different datasets. Availability: http://www.bioinfocabd.upo.es/orthofind/.
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Li H, Custer SK, Gilson T, Hao LT, Beattie CE, Androphy EJ. α-COP binding to the survival motor neuron protein SMN is required for neuronal process outgrowth. Hum Mol Genet 2015; 24:7295-307. [PMID: 26464491 DOI: 10.1093/hmg/ddv428] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/06/2015] [Indexed: 01/30/2023] Open
Abstract
Spinal muscular atrophy (SMA), a heritable neurodegenerative disease, results from insufficient levels of the survival motor neuron (SMN) protein. α-COP binds to SMN, linking the COPI vesicular transport pathway to SMA. Reduced levels of α-COP restricted development of neuronal processes in NSC-34 cells and primary cortical neurons. Remarkably, heterologous expression of human α-COP restored normal neurite length and morphology in SMN-depleted NSC-34 cells in vitro and zebrafish motor neurons in vivo. We identified single amino acid mutants of α-COP that selectively abrogate SMN binding, retain COPI-mediated Golgi-ER trafficking functionality, but were unable to support neurite outgrowth in cellular and zebrafish models of SMA. Taken together, these demonstrate the functional role of COPI association with the SMN protein in neuronal development.
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Affiliation(s)
- Hongxia Li
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
| | - Sara K Custer
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
| | - Timra Gilson
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
| | - Le Thi Hao
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Christine E Beattie
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Elliot J Androphy
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
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Bachiller S, Rybkina T, Porras-García E, Pérez-Villegas E, Tabares L, Armengol JA, Carrión AM, Ruiz R. The HERC1 E3 Ubiquitin Ligase is essential for normal development and for neurotransmission at the mouse neuromuscular junction. Cell Mol Life Sci 2015; 72:2961-71. [PMID: 25746226 PMCID: PMC11113414 DOI: 10.1007/s00018-015-1878-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 02/15/2015] [Accepted: 02/27/2015] [Indexed: 12/14/2022]
Abstract
The ubiquitin-proteasome system (UPS) plays a fundamental role in protein degradation in neurons, and there is strong evidence that it fulfills a key role in synaptic transmission. The aim of the present work was to study the implication of one component of the UPS, the HERC1 E3 Ubiquitin Ligase, in motor function and neuromuscular transmission. The tambaleante (tbl) mutant mouse carries a spontaneous mutation in HERC1 E3 Ubiquitin Ligase, provoking an ataxic phenotype that develops in the second month of life. Our results show that motor performance in mutant mice is altered at postnatal day 30, before the cerebellar neurodegeneration takes place. This defect is associated with by: (a) a reduction of the motor end-plate area, (b) less efficient neuromuscular activity in vivo, and (c) an impaired evoked neurotransmitter release. Together, these data suggest that the HERC1 E3 Ubiquitin Ligase is fundamental for normal muscle function and that it is essential for neurotransmitter release at the mouse neuromuscular junction.
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Affiliation(s)
- S. Bachiller
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
| | - T. Rybkina
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
| | - E. Porras-García
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
| | - E. Pérez-Villegas
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
| | - L. Tabares
- Department of Medical Physiology and Biophysics, University of Seville, Seville, Spain
| | - J. A. Armengol
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
- School of Medicine, University of Cartagena de Indias, Cartagena, Colombia
| | - A. M. Carrión
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
| | - R. Ruiz
- Department of Physiology, Anatomy and Cellular Biology, University of Pablo de Olavide, Carretera de Utrera Km 1, 41013 Seville, Spain
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Mukhitov AR, Nikolsky EE. The effect of electric stimulation of various frequencies and durations on microtubules in frog motor axon terminals. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2015; 459:334-7. [PMID: 25560209 DOI: 10.1134/s0012496614060076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Indexed: 11/23/2022]
Affiliation(s)
- A R Mukhitov
- Kazan Institute of Biochemistry and Biophysics, Kazan Research Center, Russian Academy of Sciences, ul. Lobachevskogo 2/31, Kazan, 420111, Tatarstan, Russia,
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Presynaptic localization of Smn and hnRNP R in axon terminals of embryonic and postnatal mouse motoneurons. PLoS One 2014; 9:e110846. [PMID: 25338097 PMCID: PMC4206449 DOI: 10.1371/journal.pone.0110846] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/23/2014] [Indexed: 11/19/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by deficiency of the ubiquitously expressed survival motoneuron (SMN) protein. SMN is crucial component of a complex for the assembly of spliceosomal small nuclear ribonucleoprotein (snRNP) particles. Other cellular functions of SMN are less characterized so far. SMA predominantly affects lower motoneurons, but the cellular basis for this relative specificity is still unknown. In contrast to nonneuronal cells where the protein is mainly localized in perinuclear regions and the nucleus, Smn is also present in dendrites, axons and axonal growth cones of isolated motoneurons invitro. However, this distribution has not been shown invivo and it is not clear whether Smn and hnRNP R are also present in presynaptic axon terminals of motoneurons in postnatal mice. Smn also associates with components not included in the classical SMN complex like RNA-binding proteins FUS, TDP43, HuD and hnRNP R which are involved in RNA processing, subcellular localization and translation. We show here that Smn and hnRNP R are present in presynaptic compartments at neuromuscular endplates of embryonic and postnatal mice. Smn and hnRNP R are localized in close proximity to each other in axons and axon terminals both invitro and invivo. We also provide new evidence for a direct interaction of Smn and hnRNP R invitro and invivo, particularly in the cytosol of motoneurons. These data point to functions of SMN beyond snRNP assembly which could be crucial for recruitment and transport of RNA particles into axons and axon terminals, a mechanism which may contribute to SMA pathogenesis.
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Mechanisms involved in spinal cord central synapse loss in a mouse model of spinal muscular atrophy. J Neuropathol Exp Neurol 2014; 73:519-35. [PMID: 24806302 DOI: 10.1097/nen.0000000000000074] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Motoneuron (MN) cell death is the histopathologic hallmark of spinal muscular atrophy (SMA), although MN loss seems to be a late event. Conversely, disruption of afferent synapses on MNs has been shown to occur early in SMA. Using a mouse model of severe SMA (SMNΔ7), we examined the mechanisms involved in impairment of central synapses. We found that MNs underwent progressive degeneration in the course of SMA, with MN loss still occurring at late stages. Loss of afferent inputs to SMA MNs was detected at embryonic stages, long before MN death. Reactive microgliosis and astrogliosis were present in the spinal cord of diseased animals after the onset of MN loss. Ultrastructural observations indicate that dendrites and microglia phagocytose adjacent degenerating presynaptic terminals. Neuronal nitric oxide synthase was upregulated in SMNΔ7 MNs, and there was an increase in phosphorylated myosin light chain expression in synaptic afferents on MNs; these observations implicate nitric oxide in MN deafferentation and suggest that the RhoA/ROCK pathway is activated. Together, our observations suggest that the earliest change occurring in SMNΔ7 mice is the loss of excitatory glutamatergic synaptic inputs to MNs; reduced excitability may enhance their vulnerability to degeneration and death.
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47
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Chronic proximal axonopathy in rats is associated with long-standing neurofilament depletion in neuromuscular junctions and behavioral deficits. J Neuropathol Exp Neurol 2014; 73:568-79. [PMID: 24806304 DOI: 10.1097/nen.0000000000000079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In rodents exposed to 3,3'-iminodipropionitrile (IDPN), neurofilaments (NFs) accumulate in swollen proximal axon segments; this also occurs in motor neurons of patients with amyotrophic lateral sclerosis. We hypothesized that early loss of NFs in neuromuscular junctions (NMJs) in IDPN proximal neuropathy would result in neuromuscular dysfunction and lead to neuromuscular detachment. Adult male rats were given 0 or 15 mmol/L IDPN in drinking water for up to 1 year. The IDPN-exposed rats dragged their tails and had impaired endurance in a grip test. Neuromuscular junctions and distal axons were examined in the levator auris longus muscle after 3, 6, 9, and 12 months. Neuromuscular junctions showed a progressive reduction in NF immunolabeling, which became undetectable in up to 70% of the NMJs after 12 months. Neurofilament labeling was also reduced in preterminal axons and in a more proximal axon level within the muscle. Triple-label analysis with antisyntaxin demonstrated that the terminals remained in place and usually contained a few minute NF bundles. Electron microscopy revealed the disappearance of terminal NFs, reduced content in synaptic vesicles, and accumulation of multilamellar bodies, but scant degeneration. Thus, IDPN proximal neurofilamentous axonopathy is associated with NF depletion in motor terminals; motor weakness and structural changes in the NMJs suggest impaired synaptic function despite long-term preservation of the NMJs.
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Bellouze S, Schäfer MK, Buttigieg D, Baillat G, Rabouille C, Haase G. Golgi fragmentation in pmn mice is due to a defective ARF1/TBCE cross-talk that coordinates COPI vesicle formation and tubulin polymerization. Hum Mol Genet 2014; 23:5961-75. [DOI: 10.1093/hmg/ddu320] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Sleigh JN, Burgess RW, Gillingwater TH, Cader MZ. Morphological analysis of neuromuscular junction development and degeneration in rodent lumbrical muscles. J Neurosci Methods 2014; 227:159-65. [PMID: 24530702 DOI: 10.1016/j.jneumeth.2014.02.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 02/04/2014] [Accepted: 02/05/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND The neuromuscular junction (NMJ) is a specialised synapse formed between a lower motor neuron and a skeletal muscle fibre, and is an early pathological target in numerous nervous system disorders, including amyotrophic lateral sclerosis (ALS), Charcot-Marie-Tooth disease (CMT), and spinal muscular atrophy (SMA). Being able to accurately visualise and quantitatively characterise the NMJ in rodent models of neurological conditions, particularly during the early stages of disease, is thus of clear importance. NEW METHOD We present a method for dissection of rodent deep lumbrical muscles located in the hind-paw, and describe how to perform immunofluorescent morphological analysis of their NMJs. RESULTS These techniques allow the temporal assessment of a number of developmental and pathological NMJ phenotypes in lumbrical muscles. COMPARISON WITH EXISTING METHODS Small muscles, such as the distal hind-limb lumbrical muscles, possess a major advantage over larger muscles, such as gastrocnemius, in that they can be whole-mounted and the entire innervation pattern visualised. This reduces preparation time and ambiguity when evaluating important neuromuscular phenotypes. CONCLUSIONS Together, these methods will allow the reader to perform a detailed and accurate analysis of the neuromuscular system in rodent models of disease in order to identify pertinent features of neuropathology.
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Affiliation(s)
- James N Sleigh
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK; The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | | | - Thomas H Gillingwater
- Centre for Integrative Physiology & Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - M Zameel Cader
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK; The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK.
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Dachs E, Piedrafita L, Hereu M, Esquerda J, Calderó J. Chronic treatment with lithium does not improve neuromuscular phenotype in a mouse model of severe spinal muscular atrophy. Neuroscience 2013; 250:417-33. [DOI: 10.1016/j.neuroscience.2013.07.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/26/2013] [Accepted: 07/11/2013] [Indexed: 12/12/2022]
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