51
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Huh S, Heckman CJ, Manuel M. Time Course of Alterations in Adult Spinal Motoneuron Properties in the SOD1(G93A) Mouse Model of ALS. eNeuro 2021; 8:ENEURO.0378-20.2021. [PMID: 33632815 PMCID: PMC8009670 DOI: 10.1523/eneuro.0378-20.2021] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 01/02/2023] Open
Abstract
Although amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease, motoneuron electrical properties are already altered during embryonic development. Motoneurons must therefore exhibit a remarkable capacity for homeostatic regulation to maintain a normal motor output for most of the life of the patient. In the present article, we demonstrate how maintaining homeostasis could come at a very high cost. We studied the excitability of spinal motoneurons from young adult SOD1(G93A) mice to end-stage. Initially, homeostasis is highly successful in maintaining their overall excitability. This initial success, however, is achieved by pushing some cells far above the normal range of passive and active conductances. As the disease progresses, both passive and active conductances shrink below normal values in the surviving cells. This shrinkage may thus promote survival, implying the previously large values contribute to degeneration. These results support the hypothesis that motoneuronal homeostasis may be "hypervigilant" in ALS and a source of accumulating stress.
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Affiliation(s)
- Seoan Huh
- Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago 60611, IL
| | - Charles J Heckman
- Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago 60611, IL
- Department of Physical Medicine and Rehabilitation, Northwestern University, Feinberg School of Medicine, Chicago 60611, IL
- Department of Physical Therapy and Human Movement Science, Northwestern University, Feinberg School of Medicine, Chicago 60611, IL
| | - Marin Manuel
- Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago 60611, IL
- Université de Paris, Saints-Pères Paris Institute for the Neurosciences (SPPIN), Centre National de la Recherche Scientifique, Paris 75006, France
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52
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Early Hypoexcitability in a Subgroup of Spinal Motoneurons in Superoxide Dismutase 1 Transgenic Mice, a Model of Amyotrophic Lateral Sclerosis. Neuroscience 2021; 463:337-353. [PMID: 33556455 DOI: 10.1016/j.neuroscience.2021.01.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 01/22/2021] [Accepted: 01/31/2021] [Indexed: 11/24/2022]
Abstract
In amyotrophic lateral sclerosis (ALS), large motoneurons degenerate first, causing muscle weakness. Transgenic mouse models with a mutation in the gene encoding the enzyme superoxide dismutase 1 (SOD1) revealed that motoneurons innervating the fast-fatigable muscular fibres disconnect very early. The cause of this peripheric disconnection has not yet been established. Early pathological signs were described in motoneurons during the postnatal period of SOD1 transgenic mice. Here, we investigated whether the early changes of electrical and morphological properties previously reported in the SOD1G85R strain also occur in the SOD1G93A-low expressor line with particular attention to the different subsets of motoneurons defined by their discharge firing pattern (transient, sustained, or delayed-onset firing). Intracellular staining and recording were performed in lumbar motoneurons from entire brainstem-spinal cord preparations of SOD1G93A-low transgenic mice and their WT littermates during the second postnatal week. Our results show that SOD1G93A-low motoneurons exhibit a dendritic overbranching similar to that described previously in the SOD1G85R strain at the same age. Further we found an hypoexcitability in the delayed-onset firing SOD1G93A-low motoneurons (lower gain and higher voltage threshold). We conclude that dendritic overbranching and early hypoexcitability are common features of both low expressor SOD1 mutants (G85R and G93A-low). In the high-expressor SOD1G93A line, we found hyperexcitability in the sustained firing motoneurons at the same period, suggesting a delay in compensatory mechanisms. Overall, our results suggest that the hypoexcitability indicate an early dysfunction of the delayed-onset motoneurons and could account as early pathological signs of the disease.
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53
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Mille T, Quilgars C, Cazalets J, Bertrand SS. Acetylcholine and spinal locomotor networks: The insider. Physiol Rep 2021; 9:e14736. [PMID: 33527727 PMCID: PMC7851432 DOI: 10.14814/phy2.14736] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 01/07/2023] Open
Abstract
This article aims to review studies that have investigated the role of neurons that use the transmitter acetylcholine (ACh) in controlling the operation of locomotor neural networks within the spinal cord. This cholinergic system has the particularity of being completely intraspinal. We describe the different effects exerted by spinal cholinergic neurons on locomotor circuitry by the pharmacological activation or blockade of this propriospinal system, as well as describing its different cellular and subcellular targets. Through the activation of one ionotropic receptor, the nicotinic receptor, and five metabotropic receptors, the M1 to M5 muscarinic receptors, the cholinergic system exerts a powerful control both on synaptic transmission and locomotor network neuron excitability. Although tremendous advances have been made in our understanding of the spinal cholinergic system's involvement in the physiology and pathophysiology of locomotor networks, gaps still remain, including the precise role of the different subtypes of cholinergic neurons as well as their pre- and postsynaptic partners. Improving our knowledge of the propriospinal cholinergic system is of major relevance to finding new cellular targets and therapeutics in countering the debilitating effects of neurodegenerative diseases and restoring motor functions after spinal cord injury.
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Affiliation(s)
- Théo Mille
- Université de BordeauxCNRS UMR 5287INCIABordeauxFrance
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54
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Gento-Caro Á, Vilches-Herrando E, García-Morales V, Portillo F, Rodríguez-Bey G, González-Forero D, Moreno-López B. Interfering with lysophosphatidic acid receptor edg2/lpa 1 signalling slows down disease progression in SOD1-G93A transgenic mice. Neuropathol Appl Neurobiol 2021; 47:1004-1018. [PMID: 33508894 DOI: 10.1111/nan.12699] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 01/18/2023]
Abstract
AIMS Alterations in excitability represent an early hallmark in Amyotrophic Lateral Sclerosis (ALS). Therefore, deciphering the factors that impact motor neuron (MN) excitability offers an opportunity to uncover further aetiopathogenic mechanisms, neuroprotective agents, therapeutic targets, and/or biomarkers in ALS. Here, we hypothesised that the lipokine lysophosphatidic acid (lpa) regulates MN excitability via the G-protein-coupled receptor lpa1 . Then, modulating lpa1 -mediated signalling might affect disease progression in the ALS SOD1-G93A mouse model. METHODS The influence of lpa-lpa1 signalling on the electrical properties, Ca2+ dynamic and survival of MNs was tested in vitro. Expression of lpa1 in cultured MNs and in the spinal cord of SOD1-G93A mice was analysed. ALS mice were chronically treated with a small-interfering RNA against lpa1 (siRNAlpa1 ) or with the lpa1 inhibitor AM095. Motor skills, MN loss, and lifespan were evaluated. RESULTS AM095 reduced MN excitability. Conversely, exogenous lpa increased MN excitability by modulating task1 'leak' potassium channels downstream of lpa1 . Lpa-lpa1 signalling evoked an excitotoxic response in MNs via voltage-sensitive calcium channels. Cultured SOD1-G93A MNs displayed lpa1 upregulation and heightened vulnerability to lpa. In transgenic mice, lpa1 was upregulated mostly in spinal cord MNs before cell loss. Chronic administration of either siRNAlpa1 or AM095 reduced lpa1 expression at least in MNs, delayed MN death, improved motor skills, and prolonged life expectancy of ALS mice. CONCLUSIONS These results suggest that stressed lpa-lpa1 signalling contributes to MN degeneration in SOD1-G93A mice. Consequently, disrupting lpa1 slows down disease progression. This highlights LPA1 signalling as a potential target and/or biomarker in ALS.
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Affiliation(s)
- Ángela Gento-Caro
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Esther Vilches-Herrando
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Victoria García-Morales
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Federico Portillo
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Guillermo Rodríguez-Bey
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Department of Human Genetics. Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - David González-Forero
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Bernardo Moreno-López
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
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55
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Deardorff AS, Romer SH, Fyffe RE. Location, location, location: the organization and roles of potassium channels in mammalian motoneurons. J Physiol 2021; 599:1391-1420. [DOI: 10.1113/jp278675] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/08/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Adam S. Deardorff
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
- Department of Neurology and Internal Medicine, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
| | - Shannon H. Romer
- Odyssey Systems Environmental Health Effects Laboratory, Navy Medical Research Unit‐Dayton Wright‐Patterson Air Force Base OH 45433 USA
| | - Robert E.W. Fyffe
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
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56
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Bączyk M, Krutki P, Zytnicki D. Is there hope that transpinal direct current stimulation corrects motoneuron excitability and provides neuroprotection in amyotrophic lateral sclerosis? Physiol Rep 2021; 9:e14706. [PMID: 33463907 PMCID: PMC7814489 DOI: 10.14814/phy2.14706] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 12/14/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of largely unknown pathophysiology, characterized by the progressive loss of motoneurons (MNs). We review data showing that in presymptomatic ALS mice, MNs display reduced intrinsic excitability and impaired level of excitatory inputs. The loss of repetitive firing specifically affects the large MNs innervating fast contracting muscle fibers, which are the most vulnerable MNs in ALS. Interventions that aimed at restoring either the intrinsic excitability or the synaptic excitation result in a decrease of disease markers in MNs and delayed neuromuscular junction denervation. We then focus on trans‐spinal direct current stimulation (tsDCS), a noninvasive tool, since it modulates the activity of spinal neurons and networks. Effects of tsDCS depend on the polarity of applied current. Recent work shows that anodal tsDCS induces long‐lasting enhancement of MN excitability and synaptic excitation of spinal MNs. Moreover, we show preliminary results indicating that anodal tsDCS enhances the excitatory synaptic inputs to MNs in ALS mice. In conclusion, we suggest that chronic application of anodal tsDCS might be useful as a complementary method in the management of ALS patients.
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Affiliation(s)
- Marcin Bączyk
- Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland
| | - Piotr Krutki
- Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland
| | - Daniel Zytnicki
- Université de Paris, Centre National de la Recherche Scientifique (CNRS), Saints-Pères Paris Institute for the Neurosciences (SPPIN), Paris, France
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57
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Park JH, Chung CG, Park SS, Lee D, Kim KM, Jeong Y, Kim ES, Cho JH, Jeon YM, Shen CKJ, Kim HJ, Hwang D, Lee SB. Cytosolic calcium regulates cytoplasmic accumulation of TDP-43 through Calpain-A and Importin α3. eLife 2020; 9:60132. [PMID: 33305734 PMCID: PMC7748415 DOI: 10.7554/elife.60132] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022] Open
Abstract
Cytoplasmic accumulation of TDP-43 in motor neurons is the most prominent pathological feature in amyotrophic lateral sclerosis (ALS). A feedback cycle between nucleocytoplasmic transport (NCT) defect and TDP-43 aggregation was shown to contribute to accumulation of TDP-43 in the cytoplasm. However, little is known about cellular factors that can control the activity of NCT, thereby affecting TDP-43 accumulation in the cytoplasm. Here, we identified via FRAP and optogenetics cytosolic calcium as a key cellular factor controlling NCT of TDP-43. Dynamic and reversible changes in TDP-43 localization were observed in Drosophila sensory neurons during development. Genetic and immunohistochemical analyses identified the cytosolic calcium-Calpain-A-Importin α3 pathway as a regulatory mechanism underlying NCT of TDP-43. In C9orf72 ALS fly models, upregulation of the pathway activity by increasing cytosolic calcium reduced cytoplasmic accumulation of TDP-43 and mitigated behavioral defects. Together, these results suggest the calcium-Calpain-A-Importin α3 pathway as a potential therapeutic target of ALS.
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Affiliation(s)
- Jeong Hyang Park
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea
| | - Chang Geon Chung
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea
| | - Sung Soon Park
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea
| | - Davin Lee
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea
| | - Kyung Min Kim
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Yeonjin Jeong
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea
| | - Eun Seon Kim
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Dementia research group, Korea Brain Research Institute (KBRI), Daegu, Republic of Korea
| | - Jae Ho Cho
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea
| | - Yu-Mi Jeon
- Dementia research group, Korea Brain Research Institute (KBRI), Daegu, Republic of Korea
| | - C-K James Shen
- Taipei Medical University/Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Hyung-Jun Kim
- Dementia research group, Korea Brain Research Institute (KBRI), Daegu, Republic of Korea
| | - Daehee Hwang
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Sung Bae Lee
- Department of Brain & Cognitive Sciences, DGIST, Daegu, Republic of Korea.,Protein dynamics-based proteotoxicity control laboratory, Basic research lab, DGIST, Daegu, Republic of Korea.,Dementia research group, Korea Brain Research Institute (KBRI), Daegu, Republic of Korea
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58
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Fogarty MJ, Mu EWH, Lavidis NA, Noakes PG, Bellingham MC. Size‐dependent dendritic maladaptations of hypoglossal motor neurons in SOD1
G93A
mice. Anat Rec (Hoboken) 2020; 304:1562-1581. [DOI: 10.1002/ar.24542] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/14/2020] [Accepted: 09/22/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Matthew J. Fogarty
- School of Biomedical Sciences The University of Queensland St Lucia Australia
- Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester Minnesota USA
| | - Erica W. H. Mu
- School of Biomedical Sciences The University of Queensland St Lucia Australia
| | - Nickolas A. Lavidis
- School of Biomedical Sciences The University of Queensland St Lucia Australia
| | - Peter G. Noakes
- School of Biomedical Sciences The University of Queensland St Lucia Australia
- Queensland Brain Institute The University of Queensland St Lucia Australia
| | - Mark C. Bellingham
- School of Biomedical Sciences The University of Queensland St Lucia Australia
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59
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Housley SN, Nardelli P, Powers RK, Rich MM, Cope TC. Chronic defects in intraspinal mechanisms of spike encoding by spinal motoneurons following chemotherapy. Exp Neurol 2020; 331:113354. [PMID: 32511953 PMCID: PMC7937189 DOI: 10.1016/j.expneurol.2020.113354] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/11/2020] [Accepted: 05/04/2020] [Indexed: 11/22/2022]
Abstract
Chemotherapy-induced sensorimotor disabilities, including gait and balance disorders, as well as physical fatigue often persist for months and sometimes years into disease free survival from cancer. While associated with impaired sensory function, chronic sensorimotor disorders might also depend on chemotherapy-induced defects in other neuron types. In this report, we extend consideration to motoneurons, which, if chronically impaired, would necessarily degrade movement behavior. The present study was undertaken to determine whether motoneurons qualify as candidate contributors to chronic sensorimotor disability independently from sensory impairment. We tested this possibility in vivo from rats 5 weeks following human-scaled treatment with one of the platinum-based compounds, oxaliplatin, widely used in chemotherapy for a variety of cancers. Action potential firing of spinal motoneurons responding to different fixed levels of electrode-current injection was measured in order to assess the neurons' intrinsic capacity for stimulus encoding. The encoding of stimulus duration and intensity corroborated in untreated control rats was severely degraded in oxaliplatin treated rats, in which motoneurons invariably exhibited erratic firing that was unsustained, unpredictable from one stimulus trial to the next, and unresponsive to changes in current strength. Direct measurements of interspike oscillations in membrane voltage combined with computer modeling pointed to aberrations in subthreshold conductances as a plausible contributor to impaired firing behavior. These findings authenticate impaired spike encoding as a candidate contributor to, in the case of motoneurons, deficits in mobility and fatigue. Aberrant firing also becomes a deficit worthy of testing in other CNS neurons as a potential contributor to perceptual and cognitive disorders induced by chemotherapy in patients.
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Affiliation(s)
- Stephen N Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA
| | - Randal K Powers
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Timothy C Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA; Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30318, USA.
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60
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Gunes ZI, Kan VWY, Ye X, Liebscher S. Exciting Complexity: The Role of Motor Circuit Elements in ALS Pathophysiology. Front Neurosci 2020; 14:573. [PMID: 32625051 PMCID: PMC7311855 DOI: 10.3389/fnins.2020.00573] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/11/2020] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the degeneration of both upper and lower motor neurons. Despite decades of research, we still to date lack a cure or disease modifying treatment, emphasizing the need for a much-improved insight into disease mechanisms and cell type vulnerability. Altered neuronal excitability is a common phenomenon reported in ALS patients, as well as in animal models of the disease, but the cellular and circuit processes involved, as well as the causal relevance of those observations to molecular alterations and final cell death, remain poorly understood. Here, we review evidence from clinical studies, cell type-specific electrophysiology, genetic manipulations and molecular characterizations in animal models and culture experiments, which argue for a causal involvement of complex alterations of structure, function and connectivity of different neuronal subtypes within the cortical and spinal cord motor circuitries. We also summarize the current knowledge regarding the detrimental role of astrocytes and reassess the frequently proposed hypothesis of glutamate-mediated excitotoxicity with respect to changes in neuronal excitability. Together, these findings suggest multifaceted cell type-, brain area- and disease stage- specific disturbances of the excitation/inhibition balance as a cardinal aspect of ALS pathophysiology.
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Affiliation(s)
- Zeynep I Gunes
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany
| | - Vanessa W Y Kan
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany
| | - XiaoQian Ye
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany
| | - Sabine Liebscher
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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61
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Excessive Homeostatic Gain in Spinal Motoneurons in a Mouse Model of Amyotrophic Lateral Sclerosis. Sci Rep 2020; 10:9049. [PMID: 32493926 PMCID: PMC7271238 DOI: 10.1038/s41598-020-65685-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 05/05/2020] [Indexed: 02/08/2023] Open
Abstract
In the mSOD1 model of ALS, the excitability of motoneurons is poorly controlled, oscillating between hyperexcitable and hypoexcitable states during disease progression. The hyperexcitability is mediated by excessive activity of voltage-gated Na+ and Ca2+ channels that is initially counteracted by aberrant increases in cell size and conductance. The balance between these opposing actions collapses, however, at the time that the denervation of muscle fibers begins at about P50, resulting in a state of hypo-excitability and cell death. We propose that this process of neurodegeneration ensues from homeostatic dysregulation of excitability and have tested this hypothesis by perturbing a signal transduction pathway that plays a major role in controlling biogenesis and cell size. Our 『homeostatic dysregulation hypothesis' predicted that neonatal mSOD1 motoneurons would be much more sensitive to such perturbations than wild type controls and our results strongly support this hypothesis. Our results have important implications for therapeutic approaches to ALS.
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62
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Jara JH, Sheets PL, Nigro MJ, Perić M, Brooks C, Heller DB, Martina M, Andjus PR, Ozdinler PH. The Electrophysiological Determinants of Corticospinal Motor Neuron Vulnerability in ALS. Front Mol Neurosci 2020; 13:73. [PMID: 32508590 PMCID: PMC7248374 DOI: 10.3389/fnmol.2020.00073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/15/2020] [Indexed: 12/12/2022] Open
Abstract
The brain is complex and heterogeneous. Even though numerous independent studies indicate cortical hyperexcitability as a potential contributor to amyotrophic lateral sclerosis (ALS) pathology, the mechanisms that are responsible for upper motor neuron (UMN) vulnerability remain elusive. To reveal the electrophysiological determinants of corticospinal motor neuron (CSMN, a.k.a UMN in mice) vulnerability, we investigated the motor cortex of hSOD1G93A mice at P30 (postnatal day 30), a presymptomatic time point. Glutamate uncaging by laser scanning photostimulation (LSPS) revealed altered dynamics especially within the inhibitory circuitry and more specifically in L2/3 of the motor cortex, whereas the excitatory microcircuits were unchanged. Observed microcircuitry changes were specific to CSMN in the motor column. Electrophysiological evaluation of the intrinsic properties in response to the microcircuit changes, as well as the exon microarray expression profiles of CSMN isolated from hSOD1G93A and healthy mice at P30, revealed the presence of a very dynamic set of events, ultimately directed to establish, maintain and retain the balance at this early stage. Also, the expression profile of key voltage-gated potassium and sodium channel subunits as well as of the inhibitory GABA receptor subunits and modulatory proteins began to suggest the challenges CSMN face at this early age. Since neurodegeneration is initiated when neurons can no longer maintain balance, the complex cellular events that occur at this critical time point help reveal how CSMN try to cope with the challenges of disease manifestation. This information is critically important for the proper modulation of UMNs and for developing effective treatment strategies.
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Affiliation(s)
- Javier H Jara
- Davee Department of Neurology and Clinical Neurological Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Patrick L Sheets
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Maximiliano José Nigro
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Mina Perić
- Institute for Physiology and Biochemistry "Ivan Djaja", Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Carolyn Brooks
- Davee Department of Neurology and Clinical Neurological Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniel B Heller
- Davee Department of Neurology and Clinical Neurological Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Marco Martina
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Pavle R Andjus
- Institute for Physiology and Biochemistry "Ivan Djaja", Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - P Hande Ozdinler
- Davee Department of Neurology and Clinical Neurological Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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63
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Fogarty MJ, Sieck GC. Spinal cord injury and diaphragm neuromotor control. Expert Rev Respir Med 2020; 14:453-464. [PMID: 32077350 PMCID: PMC7176525 DOI: 10.1080/17476348.2020.1732822] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/18/2020] [Indexed: 12/22/2022]
Abstract
Introduction: Neuromotor control of diaphragm muscle and the recovery of diaphragm activity following spinal cord injury have been narrowly focused on ventilation. By contrast, the understanding of neuromotor control for non-ventilatory expulsive/straining maneuvers (including coughing, defecation, and parturition) is relatively impoverished. This variety of behaviors are achieved via the recruitment of the diverse array of motor units that comprise the diaphragm muscle.Areas covered: The neuromotor control of ventilatory and non-ventilatory behaviors in health and in the context of spinal cord injury is explored. Particular attention is played to the neuroplasticity of phrenic motor neurons in various models of cervical spinal cord injury.Expert opinion: There is a remarkable paucity in our understanding of neuromotor control of maneuvers in spinal cord injury patients. Dysfunction of these expulsive/straining maneuvers reduces patient quality of life and contributes to severe morbidity and mortality. As spinal cord injury patient life expectancies continue to climb steadily, a nexus of spinal cord injury and age-associated comorbidities are likely to occur. While current research remains concerned only with the minutiae of ventilation, the major functional deficits of this clinical cohort will persist intractably. We posit some future research directions to avoid this scenario.
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Affiliation(s)
- Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, USA
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, USA
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64
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Brandenburg JE, Fogarty MJ, Brown AD, Sieck GC. Phrenic motor neuron loss in an animal model of early onset hypertonia. J Neurophysiol 2020; 123:1682-1690. [PMID: 32233911 DOI: 10.1152/jn.00026.2020] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Phrenic motor neuron (PhMN) development in early onset hypertonia is poorly understood. Respiratory disorders are one of the leading causes of morbidity and mortality in individuals with early onset hypertonia, such as cerebral palsy (CP), but they are largely overshadowed by a focus on physical function in this condition. Furthermore, while the brain is the focus of CP research, motor neurons, via the motor unit and neurotransmitter signaling, are the targets in clinical interventions for hypertonia. Furthermore, critical periods of spinal cord and motor unit development also coincide with the timing that the supposed brain injury occurs in CP. Using an animal model of early-onset spasticity (spa mouse [B6.Cg-Glrbspa/J] with a glycine receptor mutation), we hypothesized that removal of effective glycinergic neurotransmitter inputs to PhMNs during development will result in fewer PhMNs and reduced PhMN somal size at maturity. Adult spa (Glrb-/-), and wild-type (Glrb+/+) mice underwent unilateral retrograde labeling of PhMNs via phrenic nerve dip in tetramethylrhodamine. After three days, mice were euthanized, perfused with 4% paraformaldehyde, and the spinal cord excised and processed for confocal imaging. Spa mice had ~30% fewer PhMNs (P = 0.005), disproportionately affecting larger PhMNs. Additionally, a ~22% reduction in PhMN somal surface area (P = 0.019), an 18% increase in primary dendrites (P < 0.0001), and 24% decrease in dendritic surface area (P = 0.014) were observed. Thus, there are fewer larger PhMNs in spa mice. Fewer and smaller PhMNs may contribute to impaired diaphragm neuromotor control and contribute to respiratory morbidity and mortality in conditions of early onset hypertonia.NEW & NOTEWORTHY Phrenic motor neuron (PhMN) development in early-onset hypertonia is poorly understood. Yet, respiratory disorders are a common cause of morbidity and mortality. In spa mice, an animal model of early-onset hypertonia, we found ~30% fewer PhMNs, compared with controls. This PhMN loss disproportionately affected larger PhMNs. Thus, the number and heterogeneity of the PhMN pool are decreased in spa mice, likely contributing to the hypertonia, impaired neuromotor control, and respiratory disorders.
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Affiliation(s)
- Joline E Brandenburg
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, Minnesota.,Department of Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota.,School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Alyssa D Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Gary C Sieck
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, Minnesota.,Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
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65
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Bursch F, Kalmbach N, Naujock M, Staege S, Eggenschwiler R, Abo-Rady M, Japtok J, Guo W, Hensel N, Reinhardt P, Boeckers TM, Cantz T, Sterneckert J, Van Den Bosch L, Hermann A, Petri S, Wegner F. Altered calcium dynamics and glutamate receptor properties in iPSC-derived motor neurons from ALS patients with C9orf72, FUS, SOD1 or TDP43 mutations. Hum Mol Genet 2020; 28:2835-2850. [PMID: 31108504 DOI: 10.1093/hmg/ddz107] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/02/2019] [Accepted: 05/14/2019] [Indexed: 12/13/2022] Open
Abstract
The fatal neurodegenerative disease amyotrophic lateral sclerosis (ALS) is characterized by a profound loss of motor neurons (MNs). Until now only riluzole minimally extends life expectancy in ALS, presumably by inhibiting glutamatergic neurotransmission and calcium overload of MNs. Therefore, the aim of this study was to investigate the glutamate receptor properties and key aspects of intracellular calcium dynamics in induced pluripotent stem cell (iPSC)-derived MNs from ALS patients with C9orf72 (n = 4 cell lines), fused in sarcoma (FUS) (n = 9), superoxide dismutase 1 (SOD1) (n = 3) or transactive response DNA-binding protein 43 (TDP43) (n = 3) mutations as well as healthy (n = 7 cell lines) and isogenic controls (n = 3). Using calcium imaging, we most frequently observed spontaneous transients in mutant C9orf72 MNs. Basal intracellular calcium levels and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-induced signal amplitudes were elevated in mutant TDP43 MNs. Besides, a majority of mutant TDP43 MNs responded to 3.5-dihydroxyphenylglycine as metabotropic glutamate receptor agonist. Quantitative real-time PCR demonstrated significantly increased expression levels of AMPA and kainate receptors in mutant FUS cells compared to healthy and isogenic controls. Furthermore, the expression of kainate receptors and voltage gated calcium channels in mutant C9orf72 MNs as well as metabotropic glutamate receptors in mutant SOD1 cells was markedly elevated compared to controls. Our data of iPSC-derived MNs from familial ALS patients revealed several mutation-specific alterations in glutamate receptor properties and calcium dynamics that could play a role in ALS pathogenesis and may lead to future translational strategies with individual stratification of neuroprotective ALS treatments.
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Affiliation(s)
- Franziska Bursch
- Department of Neurology, Hannover Medical School, 30625 Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
| | - Norman Kalmbach
- Department of Neurology, Hannover Medical School, 30625 Hannover, Germany
| | - Maximilian Naujock
- Department of Neurology, Hannover Medical School, 30625 Hannover, Germany
| | - Selma Staege
- Department of Neurology, Hannover Medical School, 30625 Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
| | - Reto Eggenschwiler
- Research Group Translational Hepatology and Stem Cell Biology, Cluster of Excellence REBIRTH, Hannover Medical School, 30625 Hannover, Germany
| | | | - Julia Japtok
- Division for Neurodegenerative Diseases, Department of Neurology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Wenting Guo
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), KU Leuven-University of Leuven, BE-3000 Leuven, Belgium.,Laboratory of Neurobiology, VIB-Center for Brain & Disease Research, BE-3000 Leuven, Belgium
| | - Niko Hensel
- Institute of Neuroanatomy, Hannover Medical School, 30625 Hanover, Germany
| | | | - Tobias M Boeckers
- Institute of Anatomy and Cell Biology, Ulm University, 89081 Ulm, Germany
| | - Tobias Cantz
- Research Group Translational Hepatology and Stem Cell Biology, Cluster of Excellence REBIRTH, Hannover Medical School, 30625 Hannover, Germany
| | | | - Ludo Van Den Bosch
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), KU Leuven-University of Leuven, BE-3000 Leuven, Belgium.,Laboratory of Neurobiology, VIB-Center for Brain & Disease Research, BE-3000 Leuven, Belgium
| | - Andreas Hermann
- Division for Neurodegenerative Diseases, Department of Neurology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Susanne Petri
- Department of Neurology, Hannover Medical School, 30625 Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
| | - Florian Wegner
- Department of Neurology, Hannover Medical School, 30625 Hannover, Germany.,Center of Systems Neuroscience, Hannover, Germany
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66
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NeuroPath2Path: Classification and elastic morphing between neuronal arbors using path-wise similarity. Neuroinformatics 2020; 18:479-508. [PMID: 32107735 DOI: 10.1007/s12021-019-09450-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Neuron shape and connectivity affect function. Modern imaging methods have proven successful at extracting morphological information. One potential path to achieve analysis of this morphology is through graph theory. Encoding by graphs enables the use of high throughput informatic methods to extract and infer brain function. However, the application of graph-theoretic methods to neuronal morphology comes with certain challenges in term of complex subgraph matching and the difficulty in computing intermediate shapes in between two imaged temporal samples. Here we report a novel, efficacious graph-theoretic method that rises to the challenges. The morphology of a neuron, which consists of its overall size, global shape, local branch patterns, and cell-specific biophysical properties, can vary significantly with the cell's identity, location, as well as developmental and physiological state. Various algorithms have been developed to customize shape based statistical and graph related features for quantitative analysis of neuromorphology, followed by the classification of neuron cell types using the features. Unlike the classical feature extraction based methods from imaged or 3D reconstructed neurons, we propose a model based on the rooted path decomposition from the soma to the dendrites of a neuron and extract morphological features from each constituent path. We hypothesize that measuring the distance between two neurons can be realized by minimizing the cost of continuously morphing the set of all rooted paths of one neuron to another. To validate this claim, we first establish the correspondence of paths between two neurons using a modified Munkres algorithm. Next, an elastic deformation framework that employs the square root velocity function is established to perform the continuous morphing, which, as an added benefit, provides an effective visualization tool. We experimentally show the efficacy of NeuroPath2Path, NeuroP2P, over the state of the art.
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67
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Spinal Motoneuron TMEM16F Acts at C-boutons to Modulate Motor Resistance and Contributes to ALS Pathogenesis. Cell Rep 2020; 30:2581-2593.e7. [DOI: 10.1016/j.celrep.2020.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 11/12/2019] [Accepted: 01/31/2020] [Indexed: 12/11/2022] Open
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68
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Branchereau P, Martin E, Allain AE, Cazenave W, Supiot L, Hodeib F, Laupénie A, Dalvi U, Zhu H, Cattaert D. Relaxation of synaptic inhibitory events as a compensatory mechanism in fetal SOD spinal motor networks. eLife 2019; 8:e51402. [PMID: 31868588 PMCID: PMC6974356 DOI: 10.7554/elife.51402] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 12/20/2019] [Indexed: 12/14/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease affecting motor neurons (MNs) during late adulthood. Here, with the aim of identifying early changes underpinning ALS neurodegeneration, we analyzed the GABAergic/glycinergic inputs to E17.5 fetal MNs from SOD1G93A (SOD) mice in parallel with chloride homeostasis. Our results show that IPSCs are less frequent in SOD animals in accordance with a reduction of synaptic VIAAT-positive terminals. SOD MNs exhibited an EGABAAR10 mV more depolarized than in WT MNs associated with a KCC2 reduction. Interestingly, SOD GABAergic/glycinergic IPSCs and evoked GABAAR-currents exhibited a slower decay correlated to elevated [Cl-]i. Computer simulations revealed that a slower relaxation of synaptic inhibitory events acts as compensatory mechanism to strengthen GABA/glycine inhibition when EGABAAR is more depolarized. How such mechanisms evolve during pathophysiological processes remain to be determined, but our data indicate that at least SOD1 familial ALS may be considered as a neurodevelopmental disease.
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Affiliation(s)
| | - Elodie Martin
- University of BordeauxCNRS, INCIA, UMR 5287BordeauxFrance
| | | | | | - Laura Supiot
- University of BordeauxCNRS, INCIA, UMR 5287BordeauxFrance
| | - Fara Hodeib
- University of BordeauxCNRS, INCIA, UMR 5287BordeauxFrance
| | | | - Urvashi Dalvi
- University of BordeauxCNRS, INCIA, UMR 5287BordeauxFrance
| | - Hongmei Zhu
- University of BordeauxCNRS, INCIA, UMR 5287BordeauxFrance
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69
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Komendantov AO, Venkadesh S, Rees CL, Wheeler DW, Hamilton DJ, Ascoli GA. Quantitative firing pattern phenotyping of hippocampal neuron types. Sci Rep 2019; 9:17915. [PMID: 31784578 PMCID: PMC6884469 DOI: 10.1038/s41598-019-52611-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 09/20/2019] [Indexed: 01/19/2023] Open
Abstract
Systematically organizing the anatomical, molecular, and physiological properties of cortical neurons is important for understanding their computational functions. Hippocampome.org defines 122 neuron types in the rodent hippocampal formation based on their somatic, axonal, and dendritic locations, putative excitatory/inhibitory outputs, molecular marker expression, and biophysical properties. We augmented the electrophysiological data of this knowledge base by collecting, quantifying, and analyzing the firing responses to depolarizing current injections for every hippocampal neuron type from published experiments. We designed and implemented objective protocols to classify firing patterns based on 5 transients (delay, adapting spiking, rapidly adapting spiking, transient stuttering, and transient slow-wave bursting) and 4 steady states (non-adapting spiking, persistent stuttering, persistent slow-wave bursting, and silence). This automated approach revealed 9 unique (plus one spurious) families of firing pattern phenotypes while distinguishing potential new neuronal subtypes. Novel statistical associations emerged between firing responses and other electrophysiological properties, morphological features, and molecular marker expression. The firing pattern parameters, experimental conditions, spike times, references to the original empirical evidences, and analysis scripts are released open-source through Hippocampome.org for all neuron types, greatly enhancing the existing search and browse capabilities. This information, collated online in human- and machine-accessible form, will help design and interpret both experiments and model simulations.
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Affiliation(s)
- Alexander O Komendantov
- Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MS 2A1, Fairfax, Virginia, 2230, USA.
| | - Siva Venkadesh
- Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MS 2A1, Fairfax, Virginia, 2230, USA
| | - Christopher L Rees
- Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MS 2A1, Fairfax, Virginia, 2230, USA
| | - Diek W Wheeler
- Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MS 2A1, Fairfax, Virginia, 2230, USA
| | - David J Hamilton
- Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MS 2A1, Fairfax, Virginia, 2230, USA
| | - Giorgio A Ascoli
- Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MS 2A1, Fairfax, Virginia, 2230, USA.
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70
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Marchand‐Pauvert V, Peyre I, Lackmy‐Vallee A, Querin G, Bede P, Lacomblez L, Debs R, Pradat P. Absence of hyperexcitability of spinal motoneurons in patients with amyotrophic lateral sclerosis. J Physiol 2019; 597:5445-5467. [DOI: 10.1113/jp278117] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 09/06/2019] [Indexed: 12/18/2022] Open
Affiliation(s)
| | - Iseline Peyre
- Sorbonne Université Inserm, CNRS, Laboratoire d'Imagerie Biomédicale LIB Paris France
| | | | - Giorgia Querin
- Sorbonne Université Inserm, CNRS, Laboratoire d'Imagerie Biomédicale LIB Paris France
- Neurologie, AP‐HP Hôpital Pitié‐Salpêtrière Paris France
| | - Peter Bede
- Sorbonne Université Inserm, CNRS, Laboratoire d'Imagerie Biomédicale LIB Paris France
- Neurologie, AP‐HP Hôpital Pitié‐Salpêtrière Paris France
- Computational Neuroimaging Group Trinity College Dublin Dublin Ireland
| | | | - Rabab Debs
- Neurologie, AP‐HP Hôpital Pitié‐Salpêtrière Paris France
| | - Pierre‐François Pradat
- Sorbonne Université Inserm, CNRS, Laboratoire d'Imagerie Biomédicale LIB Paris France
- Neurologie, AP‐HP Hôpital Pitié‐Salpêtrière Paris France
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71
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Fogarty MJ, Mu EWH, Lavidis NA, Noakes PG, Bellingham MC. Size-Dependent Vulnerability of Lumbar Motor Neuron Dendritic Degeneration in SOD1 G93A Mice. Anat Rec (Hoboken) 2019; 303:1455-1471. [PMID: 31509351 DOI: 10.1002/ar.24255] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/22/2019] [Accepted: 06/29/2019] [Indexed: 12/14/2022]
Abstract
The motor neuron (MN) soma surface area is correlated with motor unit type. Larger MNs innervate fast fatigue-intermediate (FInt) or fast-fatiguable (FF) muscle fibers in type FInt and FF motor units, respectively. Smaller MNs innervate slow-twitch fatigue-resistant (S) or fast fatigue-resistant (FR) muscle fibers in type S and FR motor units, respectively. In amyotrophic lateral sclerosis (ALS), FInt and FF motor units are more vulnerable, with denervation and MN death occurring for these units before the more resilient S and FR units. Abnormal MN dendritic arbors have been observed in ALS in humans and rodent models. We used a Golgi-Cox impregnation protocol to examine soma size-dependent changes in the dendritic morphology of lumbar MNs in SOD1G93A mice, a model of ALS, at pre-symptomatic, onset and mid-disease stages. In wildtype control mice, the relationship between MN soma surface area and dendritic length or dendritic spine number was highly linear (i.e., increased MN soma size correlated with increased dendritic length and spines). By contrast, in SOD1G93A mice, this linear relationship was lost and dendritic length reduction and spine loss were observed in larger MNs, from pre-symptomatic stages onward. These changes correlated with the neuromotor symptoms of ALS in rodent models. At presymptomatic ages, changes were restricted to the larger MNs, likely to comprise vulnerable FInt and FF motor units. Our results suggest morphological changes of MN dendrites and dendritic spines are likely to contribute ALS pathogenesis, not compensate for it. Anat Rec, 303:1455-1471, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Matthew J Fogarty
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Erica W H Mu
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Nickolas A Lavidis
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Peter G Noakes
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, St Lucia, Queensland, Australia
| | - Mark C Bellingham
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
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72
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Circuit-Specific Early Impairment of Proprioceptive Sensory Neurons in the SOD1 G93A Mouse Model for ALS. J Neurosci 2019; 39:8798-8815. [PMID: 31530644 DOI: 10.1523/jneurosci.1214-19.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/24/2019] [Accepted: 09/02/2019] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which motor neurons degenerate, resulting in muscle atrophy, paralysis, and fatality. Studies using mouse models of ALS indicate a protracted period of disease development with progressive motor neuron pathology, evident as early as embryonic and postnatal stages. Key missing information includes concomitant alterations in the sensorimotor circuit essential for normal development and function of the neuromuscular system. Leveraging unique brainstem circuitry, we show in vitro evidence for reflex circuit-specific postnatal abnormalities in the jaw proprioceptive sensory neurons in the well-studied SOD1G93A mouse. These include impaired and arrhythmic action potential burst discharge associated with a deficit in Nav1.6 Na+ channels. However, the mechanoreceptive and nociceptive trigeminal ganglion neurons and the visual sensory retinal ganglion neurons were resistant to excitability changes in age-matched SOD1G93A mice. Computational modeling of the observed disruption in sensory patterns predicted asynchronous self-sustained motor neuron discharge suggestive of imminent reflexive defects, such as muscle fasciculations in ALS. These results demonstrate a novel reflex circuit-specific proprioceptive sensory abnormality in ALS.SIGNIFICANCE STATEMENT Neurodegenerative diseases have prolonged periods of disease development and progression. Identifying early markers of vulnerability can therefore help devise better diagnostic and treatment strategies. In this study, we examined postnatal abnormalities in the electrical excitability of muscle spindle afferent proprioceptive neurons in the well-studied SOD1G93A mouse model for neurodegenerative motor neuron disease, amyotrophic lateral sclerosis. Our findings suggest that these proprioceptive sensory neurons are exclusively afflicted early in the disease process relative to sensory neurons of other modalities. Moreover, they presented Nav1.6 Na+ channel deficiency, which contributed to arrhythmic burst discharge. Such sensory arrhythmia could initiate reflexive defects, such as muscle fasciculations in amyotrophic lateral sclerosis, as suggested by our computational model.
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73
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Sp1-regulated expression of p11 contributes to motor neuron degeneration by membrane insertion of TASK1. Nat Commun 2019; 10:3784. [PMID: 31439839 PMCID: PMC6706379 DOI: 10.1038/s41467-019-11637-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 07/25/2019] [Indexed: 01/18/2023] Open
Abstract
Disruption in membrane excitability contributes to malfunction and differential vulnerability of specific neuronal subpopulations in a number of neurological diseases. The adaptor protein p11, and background potassium channel TASK1, have overlapping distributions in the CNS. Here, we report that the transcription factor Sp1 controls p11 expression, which impacts on excitability by hampering functional expression of TASK1. In the SOD1-G93A mouse model of ALS, Sp1-p11-TASK1 dysregulation contributes to increased excitability and vulnerability of motor neurons. Interference with either Sp1 or p11 is neuroprotective, delaying neuron loss and prolonging lifespan in this model. Nitrosative stress, a potential factor in human neurodegeneration, stimulated Sp1 expression and human p11 promoter activity, at least in part, through a Sp1-binding site. Disruption of Sp1 or p11 also has neuroprotective effects in a traumatic model of motor neuron degeneration. Together our work suggests the Sp1-p11-TASK1 pathway is a potential target for treatment of degeneration of motor neurons. The adaptor protein p11 and K+ channel TASK1 have overlapping distributions in the CNS. Here, the authors demonstrate that the transcription factor Sp1 regulates p11 levels, which in turn affects intrinsic membrane properties and can contribute to degeneration of motor neurons in disease and injury models.
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74
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Marcuzzo S, Terragni B, Bonanno S, Isaia D, Cavalcante P, Cappelletti C, Ciusani E, Rizzo A, Regalia G, Yoshimura N, Ugolini GS, Rasponi M, Bechi G, Mantegazza M, Mantegazza R, Bernasconi P, Minati L. Hyperexcitability in Cultured Cortical Neuron Networks from the G93A-SOD1 Amyotrophic Lateral Sclerosis Model Mouse and its Molecular Correlates. Neuroscience 2019; 416:88-99. [PMID: 31400485 DOI: 10.1016/j.neuroscience.2019.07.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 11/25/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting the corticospinal tract and leading to motor neuron death. According to a recent study, magnetic resonance imaging-visible changes suggestive of neurodegeneration seem absent in the motor cortex of G93A-SOD1 ALS mice. However, it has not yet been ascertained whether the cortical neural activity is intact, or alterations are present, perhaps even from an early stage. Here, cortical neurons from this model were isolated at post-natal day 1 and cultured on multielectrode arrays. Their activity was studied with a comprehensive pool of neurophysiological analyses probing excitability, criticality and network architecture, alongside immunocytochemistry and molecular investigations. Significant hyperexcitability was visible through increased network firing rate and bursting, whereas topological changes in the synchronization patterns were apparently absent. The number of dendritic spines was increased, accompanied by elevated transcriptional levels of the DLG4 gene, NMDA receptor 1 and the early pro-apoptotic APAF1 gene. The extracellular Na+, Ca2+, K+ and Cl- concentrations were elevated, pointing to perturbations in the culture micro-environment. Our findings highlight remarkable early changes in ALS cortical neuron activity and physiology. These changes suggest that the causative factors of hyperexcitability and associated toxicity could become established much earlier than the appearance of disease symptoms, with implications for the discovery of new hypothetical therapeutic targets.
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Affiliation(s)
- Stefania Marcuzzo
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy.
| | - Benedetta Terragni
- Neurophysiopathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Silvia Bonanno
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Davide Isaia
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy; Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Department of Development and Stem Cells, CNRS UMR7104, INSERM U964, Université de Strasbourg, 67404 Illkirch CU, Strasbourg, France
| | - Paola Cavalcante
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Cristina Cappelletti
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Emilio Ciusani
- Laboratory of Clinical Pathology and Medical Genetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Ambra Rizzo
- Laboratory of Clinical Pathology and Medical Genetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Giulia Regalia
- Neuroengineering and Medical Robotics Laboratory, Politecnico di Milano, Milan 20133, Italy; Currently working at Empatica srl, Milan 20144, Italy
| | - Natsue Yoshimura
- World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Giovanni Stefano Ugolini
- Department of Electronics, Information & Bioengineering, Politecnico di Milano, Milan 20133, Italy
| | - Marco Rasponi
- Department of Electronics, Information & Bioengineering, Politecnico di Milano, Milan 20133, Italy
| | - Giulia Bechi
- Neurophysiopathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Massimo Mantegazza
- Neurophysiopathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy; Université Côte d'Azur, CNRS UMR7275, LabEx ICST, Institute of Molecular and Cellular Pharmacology, 06560 Valbonne-Sophia Antipolis, France
| | - Renato Mantegazza
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Pia Bernasconi
- Neurology IV -Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Ludovico Minati
- World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan; Complex Systems Theory Department, Institute of Nuclear Physics, Polish Academy of Sciences (IFJ-PAN), 31-342 Kraków, Poland; Center for Mind/Brain Sciences (CIMeC), University of Trento, 38123 Trento, Italy
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75
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Giusto E, Codrich M, Leo G, Francardo V, Coradazzi M, Parenti R, Gulisano M, Vicario N, Gulino R, Leanza G. Compensatory changes in degenerating spinal motoneurons sustain functional sparing in the SOD1‐G93A mouse model of amyotrophic lateral sclerosis. J Comp Neurol 2019; 528:231-243. [DOI: 10.1002/cne.24751] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/07/2019] [Accepted: 07/24/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Elena Giusto
- B.R.A.I.N. Laboratory for Neurogenesis and Repair, Department of Life Sciences University of Trieste Trieste Italy
| | - Marta Codrich
- B.R.A.I.N. Laboratory for Neurogenesis and Repair, Department of Life Sciences University of Trieste Trieste Italy
| | - Gioacchino Leo
- B.R.A.I.N. Laboratory for Neurogenesis and Repair, Department of Life Sciences University of Trieste Trieste Italy
| | - Veronica Francardo
- B.R.A.I.N. Laboratory for Neurogenesis and Repair, Department of Life Sciences University of Trieste Trieste Italy
| | - Marino Coradazzi
- B.R.A.I.N. Laboratory for Neurogenesis and Repair, Department of Life Sciences University of Trieste Trieste Italy
| | - Rosalba Parenti
- Department of Biomedical and Biotechnological Sciences, Physiology Section University of Catania Catania Italy
- Molecular Preclinical and Translational Imaging Research Centre ‐ IMPRonTE University of Catania Italy
| | - Massimo Gulisano
- Molecular Preclinical and Translational Imaging Research Centre ‐ IMPRonTE University of Catania Italy
- Department of Drug Sciences University of Catania Catania Italy
| | - Nunzio Vicario
- Department of Biomedical and Biotechnological Sciences, Physiology Section University of Catania Catania Italy
| | - Rosario Gulino
- Department of Biomedical and Biotechnological Sciences, Physiology Section University of Catania Catania Italy
- Molecular Preclinical and Translational Imaging Research Centre ‐ IMPRonTE University of Catania Italy
| | - Giampiero Leanza
- B.R.A.I.N. Laboratory for Neurogenesis and Repair, Department of Life Sciences University of Trieste Trieste Italy
- Molecular Preclinical and Translational Imaging Research Centre ‐ IMPRonTE University of Catania Italy
- Department of Drug Sciences University of Catania Catania Italy
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76
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LoRusso E, Hickman JJ, Guo X. Ion channel dysfunction and altered motoneuron excitability in ALS. NEUROLOGICAL DISORDERS & EPILEPSY JOURNAL 2019; 3:124. [PMID: 32313901 PMCID: PMC7170321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dysregulated excitability is a hallmark of Amyotrophic Lateral Sclerosis (ALS) pathology both in ALS research models and in clinical settings. This primarily results from the dysfunction of Na+, K+, and Ca2+ ion channels responsible for maintaining neuronal thresholds and executing signal transduction or synaptic transmission. The exact dysfunction that each of these ion channel currents display in ALS pathology can vary between different ALS models, mainly induced pluripotent stem cell (iPSC) derived human motoneurons and ALS mouse models. Moreover, results can vary further across ALS mutations and between different developmental periods of these disease models. This review attempts to gather observations regarding ion channel dysfunction contributing to both hyperexcitable and hypoexcitable phenotypes in ALS motoneurons both in vivo and in vitro, so as to assess their potential as therapeutic targets.
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77
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Ragagnin AMG, Shadfar S, Vidal M, Jamali MS, Atkin JD. Motor Neuron Susceptibility in ALS/FTD. Front Neurosci 2019; 13:532. [PMID: 31316328 PMCID: PMC6610326 DOI: 10.3389/fnins.2019.00532] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/08/2019] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the death of both upper and lower motor neurons (MNs) in the brain, brainstem and spinal cord. The neurodegenerative mechanisms leading to MN loss in ALS are not fully understood. Importantly, the reasons why MNs are specifically targeted in this disorder are unclear, when the proteins associated genetically or pathologically with ALS are expressed ubiquitously. Furthermore, MNs themselves are not affected equally; specific MNs subpopulations are more susceptible than others in both animal models and human patients. Corticospinal MNs and lower somatic MNs, which innervate voluntary muscles, degenerate more readily than specific subgroups of lower MNs, which remain resistant to degeneration, reflecting the clinical manifestations of ALS. In this review, we discuss the possible factors intrinsic to MNs that render them uniquely susceptible to neurodegeneration in ALS. We also speculate why some MN subpopulations are more vulnerable than others, focusing on both their molecular and physiological properties. Finally, we review the anatomical network and neuronal microenvironment as determinants of MN subtype vulnerability and hence the progression of ALS.
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Affiliation(s)
- Audrey M G Ragagnin
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Sina Shadfar
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Marta Vidal
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Md Shafi Jamali
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Julie D Atkin
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.,Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
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78
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Pathophysiology and Diagnosis of ALS: Insights from Advances in Neurophysiological Techniques. Int J Mol Sci 2019; 20:ijms20112818. [PMID: 31185581 PMCID: PMC6600525 DOI: 10.3390/ijms20112818] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 05/27/2019] [Accepted: 06/06/2019] [Indexed: 12/28/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and fatal neurodegenerative disorder of the motor neurons, characterized by focal onset of muscle weakness and incessant disease progression. While the presence of concomitant upper and lower motor neuron signs has been recognized as a pathognomonic feature of ALS, the pathogenic importance of upper motor neuron dysfunction has only been recently described. Specifically, transcranial magnetic stimulation (TMS) techniques have established cortical hyperexcitability as an important pathogenic mechanism in ALS, correlating with neurodegeneration and disease spread. Separately, ALS exhibits a heterogeneous clinical phenotype that may lead to misdiagnosis, particularly in the early stages of the disease process. Cortical hyperexcitability was shown to be a robust diagnostic biomarker if ALS, reliably differentiating ALS from neuromuscular mimicking disorders. The present review will provide an overview of key advances in the understanding of ALS pathophysiology and diagnosis, focusing on the importance of cortical hyperexcitability and its relationship to advances in genetic and molecular processes implicated in ALS pathogenesis.
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79
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Jiang T, Handley E, Brizuela M, Dawkins E, Lewis KEA, Clark RM, Dickson TC, Blizzard CA. Amyotrophic lateral sclerosis mutant TDP-43 may cause synaptic dysfunction through altered dendritic spine function. Dis Model Mech 2019; 12:dmm.038109. [PMID: 31036551 PMCID: PMC6550035 DOI: 10.1242/dmm.038109] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/12/2019] [Indexed: 12/12/2022] Open
Abstract
Altered cortical excitability and synapse dysfunction are early pathogenic events in amyotrophic lateral sclerosis (ALS) patients and animal models. Recent studies propose an important role for TAR DNA-binding protein 43 (TDP-43), the mislocalization and aggregation of which are key pathological features of ALS. However, the relationship between ALS-linked TDP-43 mutations, excitability and synaptic function is not fully understood. Here, we investigate the role of ALS-linked mutant TDP-43 in synapse formation by examining the morphological, immunocytochemical and excitability profile of transgenic mouse primary cortical pyramidal neurons that over-express human TDP-43A315T. In TDP-43A315T cortical neurons, dendritic spine density was significantly reduced compared to wild-type controls. TDP-43A315T over-expression increased the total levels of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropinionic acid (AMPA) glutamate receptor subunit GluR1, yet the localization of GluR1 to the dendritic spine was reduced. These postsynaptic changes were coupled with a decrease in the amount of the presynaptic marker synaptophysin that colocalized with dendritic spines. Interestingly, action potential generation was reduced in TDP-43A315T pyramidal neurons. This work reveals a crucial effect of the over-expression mutation TDP-43A315T on the formation of synaptic structures and the recruitment of GluR1 to the synaptic membrane. This pathogenic effect may be mediated by cytoplasmic mislocalization of TDP-43A315T. Loss of synaptic GluR1, and reduced excitability within pyramidal neurons, implicates hypoexcitability and attenuated synaptic function in the pathogenic decline of neuronal function in TDP-43-associated ALS. Further studies into the mechanisms underlying AMPA receptor-mediated excitability changes within the ALS cortical circuitry may yield novel therapeutic targets for treatment of this devastating disease. Summary: Loss of synaptic GluR1, and reduced excitability within pyramidal neurons, implicates hypoexcitability and attenuated synaptic function in the pathogenic decline of neuronal function in TDP-43-associated ALS.
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Affiliation(s)
- Tongcui Jiang
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Emily Handley
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Mariana Brizuela
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Edgar Dawkins
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Katherine E A Lewis
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Rosemary M Clark
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Tracey C Dickson
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
| | - Catherine A Blizzard
- Menzies Institute for Medical Research, University of Tasmania, Medical Sciences Precinct, 17 Liverpool Street, Hobart, TAS 7000, Australia
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80
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Peikert K, Naumann M, Günther R, Wegner F, Hermann A. Off-Label Treatment of 4 Amyotrophic Lateral Sclerosis Patients With 4-Aminopyridine. J Clin Pharmacol 2019; 59:1400-1404. [PMID: 31038230 DOI: 10.1002/jcph.1437] [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] [Received: 01/15/2019] [Accepted: 04/11/2019] [Indexed: 02/06/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disorder characterized by degeneration of the upper and lower motor neuron. Among the at least 25 known genes associated with familial (hereditary) and sporadic ALS, mutations in fused-in-sarcoma (FUS) and superoxide dismutase 1 (SOD1) have been extensively investigated in the past years, with emphasis on altered excitability of affected neurons. Recently, we reported on hypoexcitability and increased cell death in a FUS/SOD1-ALS-induced pluripotent stem cell-derived motor neuron model, which was partly reversible by a treatment with the potassium channel blocker 4-aminopyridine (4-AP). Based on this study, we aimed to examine this US Food and Drug Administration-approved drug as a potential individualized treatment for patients with ALS. We therefore retrospectively investigated 4 FUS/SOD1-ALS patients who were prescribed 4-AP. Two patients expressed an improved quality of life due to regain of facial muscle motor function and decreased disease progression rate, respectively. Together with recent pathophysiologic findings, this case series supports the need for clinical trials to examine the efficacy of this potential treatment in distinct ALS subgroups and disease stages.
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Affiliation(s)
- Kevin Peikert
- Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Marcel Naumann
- Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,DZNE, German Centre for Neurodegenerative Diseases, Research Site Dresden, Dresden, Germany.,Translational Neurodegeneration Section Albrecht Kossel, Department of Neurology, University Medical Center Rostock, University of Rostock, Rostock, Germany
| | - René Günther
- Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,DZNE, German Centre for Neurodegenerative Diseases, Research Site Dresden, Dresden, Germany
| | - Florian Wegner
- Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Andreas Hermann
- Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,DZNE, German Center for Neurodegenerative Diseases, Research Site Rostock/Greifswald, Rostock, Germany.,Translational Neurodegeneration Section Albrecht Kossel, Department of Neurology, University Medical Center Rostock, University of Rostock, Rostock, Germany.,Center for Transdisciplinary Neurosciences Rostock (CTNR), University Medical Center Rostock, University of Rostock, Rostock, Germany
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81
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Buskila Y, Kékesi O, Bellot-Saez A, Seah W, Berg T, Trpceski M, Yerbury JJ, Ooi L. Dynamic interplay between H-current and M-current controls motoneuron hyperexcitability in amyotrophic lateral sclerosis. Cell Death Dis 2019; 10:310. [PMID: 30952836 PMCID: PMC6450866 DOI: 10.1038/s41419-019-1538-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/13/2019] [Accepted: 03/19/2019] [Indexed: 12/13/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a type of motor neuron disease (MND) in which humans lose motor functions due to progressive loss of motoneurons in the cortex, brainstem, and spinal cord. In patients and in animal models of MND it has been observed that there is a change in the properties of motoneurons, termed neuronal hyperexcitability, which is an exaggerated response of the neurons to a stimulus. Previous studies suggested neuronal excitability is one of the leading causes for neuronal loss, however the factors that instigate excitability in neurons over the course of disease onset and progression are not well understood, as these studies have looked mainly at embryonic or early postnatal stages (pre-symptomatic). As hyperexcitability is not a static phenomenon, the aim of this study was to assess the overall excitability of upper motoneurons during disease progression, specifically focusing on their oscillatory behavior and capabilities to fire repetitively. Our results suggest that increases in the intrinsic excitability of motoneurons are a global phenomenon of aging, however the cellular mechanisms that underlie this hyperexcitability are distinct in SOD1G93A ALS mice compared with wild-type controls. The ionic mechanism driving increased excitability involves alterations of the expression levels of HCN and KCNQ channel genes leading to a complex dynamic of H-current and M-current activation. Moreover, we show a negative correlation between the disease onset and disease progression, which correlates with a decrease in the expression level of HCN and KCNQ channels. These findings provide a potential explanation for the increased vulnerability of motoneurons to ALS with aging.
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Affiliation(s)
- Yossi Buskila
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia.
- School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia.
| | - Orsolya Kékesi
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia
- School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Alba Bellot-Saez
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia
- School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia
| | - Winston Seah
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia
- School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Tracey Berg
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Michael Trpceski
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Justin J Yerbury
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Lezanne Ooi
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia.
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82
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83
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Manuel M, Zytnicki D. Molecular and electrophysiological properties of mouse motoneuron and motor unit subtypes. CURRENT OPINION IN PHYSIOLOGY 2018; 8:23-29. [PMID: 32551406 DOI: 10.1016/j.cophys.2018.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The field of motoneuron and motor unit physiology in mammals has deeply evolved the last decade thanks to the parallel development of mouse genetics and transcriptomic analysis and of in vivo mouse preparations that allow intracellular electrophysiological recordings of motoneurons. We review the efforts made to investigate the electrophysiological properties of the different functional subtypes of mouse motoneurons, to decipher the mosaic of molecular markers specifically expressed in each subtype, and to elucidate which of those factors drive the identity of motoneurons.
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Affiliation(s)
- Marin Manuel
- Center for Neurophysics, Physiology and Pathology, Paris Descartes University, CNRS UMR 8119, Paris, France
| | - Daniel Zytnicki
- Center for Neurophysics, Physiology and Pathology, Paris Descartes University, CNRS UMR 8119, Paris, France
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84
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Silbernagel N, Walecki M, Schäfer MKH, Kessler M, Zobeiri M, Rinné S, Kiper AK, Komadowski MA, Vowinkel KS, Wemhöner K, Fortmüller L, Schewe M, Dolga AM, Scekic-Zahirovic J, Matschke LA, Culmsee C, Baukrowitz T, Monassier L, Ullrich ND, Dupuis L, Just S, Budde T, Fabritz L, Decher N. The VAMP-associated protein VAPB is required for cardiac and neuronal pacemaker channel function. FASEB J 2018; 32:6159-6173. [PMID: 29879376 PMCID: PMC6629115 DOI: 10.1096/fj.201800246r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels encode neuronal and cardiac pacemaker currents. The composition of pacemaker channel complexes in different tissues is poorly understood, and the presence of additional HCN modulating subunits was speculated. Here we show that vesicle-associated membrane protein-associated protein B (VAPB), previously associated with a familial form of amyotrophic lateral sclerosis 8, is an essential HCN1 and HCN2 modulator. VAPB significantly increases HCN2 currents and surface expression and has a major influence on the dendritic neuronal distribution of HCN2. Severe cardiac bradycardias in VAPB-deficient zebrafish and VAPB-/- mice highlight that VAPB physiologically serves to increase cardiac pacemaker currents. An altered T-wave morphology observed in the ECGs of VAPB-/- mice supports the recently proposed role of HCN channels for ventricular repolarization. The critical function of VAPB in native pacemaker channel complexes will be relevant for our understanding of cardiac arrhythmias and epilepsies, and provides an unexpected link between these diseases and amyotrophic lateral sclerosis.-Silbernagel, N., Walecki, M., Schäfer, M.-K. H., Kessler, M., Zobeiri, M., Rinné, S., Kiper, A. K., Komadowski, M. A., Vowinkel, K. S., Wemhöner, K., Fortmüller, L., Schewe, M., Dolga, A. M., Scekic-Zahirovic, J., Matschke, L. A., Culmsee, C., Baukrowitz, T., Monassier, L., Ullrich, N. D., Dupuis, L., Just, S., Budde, T., Fabritz, L., Decher, N. The VAMP-associated protein VAPB is required for cardiac and neuronal pacemaker channel function.
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Affiliation(s)
- Nicole Silbernagel
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Magdalena Walecki
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Martin K-H Schäfer
- Institute of Anatomy and Cell Biology, Philipps University, Marburg, Germany
| | - Mirjam Kessler
- Molecular Cardiology, Department of Internal Medicine II, University Hospital Ulm, Ulm, Germany
| | | | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Marlene A Komadowski
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany.,Institute of Anatomy and Cell Biology, Philipps University, Marburg, Germany
| | - Kirsty S Vowinkel
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Konstantin Wemhöner
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Lisa Fortmüller
- Department of Cardiology II - Electrophysiology, University Hospital Münster, University of Münster, Munster, Germany
| | - Marcus Schewe
- Institute of Physiology, Christian-Albrechts University, Kiel, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, Phillips University, Marburg, Germany
| | - Jelena Scekic-Zahirovic
- Laboratoire de Pharmacologie et Toxicologie NeuroCardiovasculaire, Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Lina A Matschke
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, Phillips University, Marburg, Germany
| | - Thomas Baukrowitz
- Institute of Physiology, Christian-Albrechts University, Kiel, Germany
| | - Laurent Monassier
- Laboratoire de Pharmacologie et Toxicologie NeuroCardiovasculaire, Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Nina D Ullrich
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Luc Dupuis
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université de Strasbourg, Strasbourg, France.,INSERM, Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Steffen Just
- Molecular Cardiology, Department of Internal Medicine II, University Hospital Ulm, Ulm, Germany
| | - Thomas Budde
- Institute for Physiology I, University of Münster, Munster, Germany
| | - Larissa Fabritz
- Department of Cardiology II - Electrophysiology, University Hospital Münster, University of Münster, Munster, Germany.,Institute of Cardiovascular Sciences, University Hospital Birmingham, University of Birmingham, Birmingham, United Kingdom.,Department of Cardiology, University Hospital Birmingham, University of Birmingham, Birmingham, United Kingdom.,Division of Rhythmology, Department of Genetic Epidemiology, University Hospital Münster, University of Münster, Munster, Germany.,Institute of Human Genetics, Department of Genetic Epidemiology, University Hospital Münster, University of Münster, Munster, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
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85
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Ghezzi F, Monni L, Nistri A. Functional up-regulation of the M-current by retigabine contrasts hyperexcitability and excitotoxicity on rat hypoglossal motoneurons. J Physiol 2018; 596:2611-2629. [PMID: 29736957 DOI: 10.1113/jp275906] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 04/23/2018] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Excessive neuronal excitability characterizes several neuropathological conditions, including neurodegenerative diseases such as amyotrophic lateral sclerosis. Hypoglossal motoneurons (HMs), which control tongue muscles, are extremely vulnerable to this disease and undergo damage and death when exposed to an excessive glutamate extracellular concentration that causes excitotoxicity. Our laboratory devised an in vitro model of excitotoxicity obtained by pharmacological blockade of glutamate transporters. In this paradigm, HMs display hyperexcitability, collective bursting and eventually cell death. The results of the present study show that pharmacological up-regulation of a K+ current (M-current), via application of the anti-convulsant retigabine, prevented all hallmarks of HM excitotoxicity, comprising bursting, generation of reactive oxygen species, expression of toxic markers and cell death. ○Our data may have translational value to develop new treatments against neurological diseases by using positive pharmacological modulators of the M-current. ABSTRACT Neuronal hyperexcitability is a symptom characterizing several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). In the ALS bulbar form, hypoglossal motoneurons (HMs) are an early target for neurodegeneration because of their high vulnerability to metabolic insults. In recent years, our laboratory has developed an in vitro model of a brainstem slice comprising the hypoglossal nucleus in which HM neurodegeneration is achieved by blocking glutamate clearance with dl-threo-β-benzyloxyaspartate (TBOA), thus leading to delayed excitotoxicity. During this process, HMs display a set of hallmarks such as hyperexcitability (and network bursting), reactive oxygen species (ROS) generation and, finally, cell death. The present study aimed to investigate whether blocking early hyperexcitability and bursting with the anti-convulsant drug retigabine was sufficient to achieve neuroprotection against excitotoxicity. Retigabine is a selective positive allosteric modulator of the M-current (IM ), an endogenous mechanism that neurons (comprising HMs) express to dampen excitability. Retigabine (10 μm; co-applied with TBOA) contrasted ROS generation, release of endogenous toxic factors into the HM cytoplasm and excitotoxicity-induced HM death. Electrophysiological experiments showed that retigabine readily contrasted and arrested bursting evoked by TBOA administration. Because neuronal IM subunits (Kv7.2, Kv7.3 and Kv7.5) were expressed in the hypoglossal nucleus and in functionally connected medullary nuclei, we suggest that they were responsible for the strong reduction in network excitability, a potent phenomenon for achieving neuroprotection against TBOA-induced excitotoxicity. The results of the present study may have translational value for testing novel positive pharmacological modulators of the IM under pathological conditions (including neurodegenerative disorders) characterized by excessive neuronal excitability.
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Affiliation(s)
- Filippo Ghezzi
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Laura Monni
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Andrea Nistri
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
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86
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Fogarty MJ. The bigger they are the harder they fall: size-dependent vulnerability of motor neurons in amyotrophic lateral sclerosis. J Physiol 2018; 596:2471-2472. [PMID: 29719046 DOI: 10.1113/jp276312] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, USA
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87
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Brandenburg JE, Gransee HM, Fogarty MJ, Sieck GC. Differences in lumbar motor neuron pruning in an animal model of early onset spasticity. J Neurophysiol 2018; 120:601-609. [PMID: 29718808 DOI: 10.1152/jn.00186.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Motor neuron (MN) development in early onset spasticity is poorly understood. For example, spastic cerebral palsy (sCP), the most common motor disability of childhood, is poorly predicted by brain imaging, yet research remains focused on the brain. By contrast, MNs, via the motor unit and neurotransmitter signaling, are the target of most therapeutic spasticity treatments and are the final common output of motor control. MN development in sCP is a critical knowledge gap, because the late embryonic and postnatal periods are not only when the supposed brain injury occurs but also are critical times for spinal cord neuromotor development. Using an animal model of early onset spasticity [ spa mouse (B6.Cg- Glrbspa/J) with a glycine (Gly) receptor mutation], we hypothesized that removal of effective glycinergic neurotransmitter inputs to MNs during development will influence MN pruning (including primary dendrites) and MN size. Spa (Glrb-/-) and wild-type (Glrb+/+) mice, ages 4-9 wk, underwent unilateral retrograde labeling of the tibialis anterior muscle MNs via peroneal nerve dip in tetramethylrhodamine. After 3 days, mice were euthanized and perfused with 4% paraformaldehyde, and the spinal cord was excised and processed for confocal imaging. Spa mice had ~61% fewer lumbar tibialis anterior MNs ( P < 0.01), disproportionately affecting larger MNs. Additionally, a ~23% reduction in tibialis anterior MN somal surface area ( P < 0.01) and a 12% increase in primary dendrites ( P = 0.046) were observed. Thus MN pruning and MN somal surface area are abnormal in early onset spasticity. Fewer and smaller MNs may contribute to the spastic phenotype. NEW & NOTEWORTHY Motor neuron (MN) development in early onset spasticity is poorly understood. In an animal model of early onset spasticity, spa mice, we found ~61% fewer lumbar tibialis anterior MNs compared with controls. This MN loss disproportionately affected larger MNs. Thus number and heterogeneity of the MN pool are decreased in spa mice, likely contributing to the spastic phenotype.
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Affiliation(s)
- Joline E Brandenburg
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine , Rochester, Minnesota.,Department of Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Heather M Gransee
- Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine , Rochester, Minnesota.,School of Biomedical Sciences, The University of Queensland , Brisbane , Australia
| | - Gary C Sieck
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine , Rochester, Minnesota.,Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine , Rochester, Minnesota.,Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
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88
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Abstract
A subgroup of the neurons that control muscles becomes less excitable shortly before the symptoms of ALS develop.
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Affiliation(s)
- Simon A Sharples
- Hotchkiss Brain InstituteUniversity of CalgaryCalgaryCanada
- Department of NeuroscienceUniversity of CalgaryCalgaryCanada
| | - Patrick J Whelan
- Hotchkiss Brain InstituteUniversity of CalgaryCalgaryCanada
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary MedicineUniversity of CalgaryCalgaryCanada
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89
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Sebastião AM, Rei N, Ribeiro JA. Amyotrophic Lateral Sclerosis (ALS) and Adenosine Receptors. Front Pharmacol 2018; 9:267. [PMID: 29713276 PMCID: PMC5911503 DOI: 10.3389/fphar.2018.00267] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/09/2018] [Indexed: 12/11/2022] Open
Abstract
In the present review we discuss the potential involvement of adenosinergic signaling, in particular the role of adenosine receptors, in amyotrophic lateral sclerosis (ALS). Though the literature on this topic is not abundant, the information so far available on adenosine receptors in animal models of ALS highlights the interest to continue to explore the role of these receptors in this neurodegenerative disease. Indeed, all motor neurons affected in ALS are responsive to adenosine receptor ligands but interestingly, there are alterations in pre-symptomatic or early symptomatic stages that mirror those in advanced disease stages. Information starts to emerge pointing toward a beneficial role of A2A receptors (A2AR), most probably at early disease states, and a detrimental role of caffeine, in clear contrast with what occurs in other neurodegenerative diseases. However, some evidence also exists on a beneficial action of A2AR antagonists. It may happen that there are time windows where A2AR prove beneficial and others where their blockade is required. Furthermore, the same changes may not occur simultaneously at the different synapses. In line with this, it is not fully understood if ALS is a dying back disease or if it propagates in a centrifugal way. It thus seems crucial to understand how motor neuron dysfunction occurs, how adenosine receptors are involved in those dysfunctions and whether the early changes in purinergic signaling are compensatory or triggers for the disease. Getting this information is crucial before starting the design of purinergic based strategies to halt or delay disease progression.
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Affiliation(s)
- Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Nádia Rei
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Joaquim A Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
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90
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Martínez-Silva MDL, Imhoff-Manuel RD, Sharma A, Heckman CJ, Shneider NA, Roselli F, Zytnicki D, Manuel M. Hypoexcitability precedes denervation in the large fast-contracting motor units in two unrelated mouse models of ALS. eLife 2018; 7:30955. [PMID: 29580378 PMCID: PMC5922970 DOI: 10.7554/elife.30955] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 03/14/2018] [Indexed: 12/17/2022] Open
Abstract
Hyperexcitability has been suggested to contribute to motoneuron degeneration in amyotrophic lateral sclerosis (ALS). If this is so, and given that the physiological type of a motor unit determines the relative susceptibility of its motoneuron in ALS, then one would expect the most vulnerable motoneurons to display the strongest hyperexcitability prior to their degeneration, whereas the less vulnerable should display a moderate hyperexcitability, if any. We tested this hypothesis in vivo in two unrelated ALS mouse models by correlating the electrical properties of motoneurons with their physiological types, identified based on their motor unit contractile properties. We found that, far from being hyperexcitable, the most vulnerable motoneurons become unable to fire repetitively despite the fact that their neuromuscular junctions were still functional. Disease markers confirm that this loss of function is an early sign of degeneration. Our results indicate that intrinsic hyperexcitability is unlikely to be the cause of motoneuron degeneration. Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a fatal disorder of the nervous system. Early symptoms include muscle weakness, unsteadiness and slurred speech. These symptoms arise because the neurons that control muscles – the motoneurons – lose their ability to make the muscles contract. Eventually, the muscles become paralyzed, with more and more muscles affected over time. Most patients die within a few years of diagnosis when the disease destroys the muscles that control breathing. Muscles are made up of muscle fibers. Each motoneuron controls a bundle of muscle fibers, and the motoneuron and its muscle fibers together make up a motor unit. A single muscle contains hundreds of motor units. These consist of several different types, which differ in how many muscle fibers they contain, how fast those muscle fibers can contract, and how fatigable the muscle fibers are. In ALS, motoneurons become detached from their muscle fibers, causing motor units to break down. But what triggers this process? One long-standing idea is that motoneurons begin to respond excessively to commands from the brain and spinal cord. In other words, they become hyperexcitable, which ultimately leads to their death. But some more recent studies of ALS suggest the opposite, namely that motoneurons become less active, or hypoexcitable. To distinguish between these possibilities, Martinez-Silva et al. took advantage of the fact that different types of motor unit break down at different rates in ALS. Large motor units containing fast-contracting muscle fibers break down before smaller motor units. By measuring the activity of motor units in two mouse models of ALS, Martinez-Silva et al. showed that large motoneurons are hypoexcitable. In other words, the motoneurons that are most vulnerable to ALS respond too little to commands from the nervous system, rather than too much. Studies of specific proteins inside the cells confirmed that hypoexcitable motoneurons are further along in the disease process than other motoneurons. Hypoexcitability is thus a key player in the ALS disease process. Developing drugs to target this hypoexcitability may be a promising strategy for the future of this condition.
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Affiliation(s)
| | - Rebecca D Imhoff-Manuel
- Centre de Neurophysique, Physiologie et Pathologie, CNRS, Université Paris Descartes, Paris, France
| | - Aarti Sharma
- Center for Motor Neuron Biology and Disease, Department of Neurology, Columbia University, New York, United States
| | - C J Heckman
- Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago, United States.,Department of Physical Medicine and Rehabilitation, Northwestern University, Feinberg School of Medicine, Chicago, United States.,Department of Physical Therapy and Human Movement Science, Northwestern University, Feinberg School of Medicine, Chicago, United States
| | - Neil A Shneider
- Center for Motor Neuron Biology and Disease, Department of Neurology, Columbia University, New York, United States
| | | | - Daniel Zytnicki
- Centre de Neurophysique, Physiologie et Pathologie, CNRS, Université Paris Descartes, Paris, France
| | - Marin Manuel
- Centre de Neurophysique, Physiologie et Pathologie, CNRS, Université Paris Descartes, Paris, France.,Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago, United States
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91
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Dukkipati SS, Garrett TL, Elbasiouny SM. The vulnerability of spinal motoneurons and soma size plasticity in a mouse model of amyotrophic lateral sclerosis. J Physiol 2018; 596:1723-1745. [PMID: 29502344 DOI: 10.1113/jp275498] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/07/2018] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Motoneuron soma size is a largely plastic property that is altered during amyotrophic lateral sclerosis (ALS) progression. We report evidence of systematic spinal motoneuron soma size plasticity in mutant SOD1-G93A mice at various disease stages and across sexes, spinal regions and motoneuron types. We show that disease-vulnerable motoneurons exhibit early increased soma sizes. We show via computer simulations that the measured changes in soma size have a profound impact on the excitability of disease-vulnerable motoneurons. This study reveals a novel form of plasticity in ALS and suggests a potential target for altering motoneuron function and survival. ABSTRACT α-Motoneuron soma size is correlated with the cell's excitability and function, and has been posited as a plastic property that changes during cellular maturation, injury and disease. This study examined whether α-motoneuron somas change in size over disease progression in the G93A mouse model of amyotrophic lateral sclerosis (ALS), a disease characterized by progressive motoneuron death. We used 2D- and 3D-morphometric analysis of motoneuron size and measures of cell density at four key disease stages: neonatal (P10 - with earliest known disease changes); young adult (P30 - presymptomatic with early motoneuron death); symptom onset (P90 - with death of 70-80% of motoneurons); and end-stage (P120+ - with full paralysis of hindlimbs). We additionally examined differences in lumbar vs. sacral vs. cervical motoneurons; in motoneurons from male vs. female mice; and in fast vs. slow motoneurons. We present the first evidence of plastic changes in the soma size of spinal α-motoneurons occurring throughout different stages of ALS with profound effects on motoneuron excitability. Somatic changes are time dependent and are characterized by early-stage enlargement (P10 and P30); no change around symptom onset; and shrinkage at end-stage. A key finding in the study indicates that disease-vulnerable motoneurons exhibit increased soma sizes (P10 and P30). This pattern was confirmed across spinal cord regions, genders and motoneuron types. This extends the theory of motoneuron size-based vulnerability in ALS: not only are larger motoneurons more vulnerable to death in ALS, but are also enlarged further in the disease. Such information is valuable for identifying ALS pathogenesis mechanisms.
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Affiliation(s)
- S Shekar Dukkipati
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, OH, 45435, USA
| | - Teresa L Garrett
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, OH, 45435, USA
| | - Sherif M Elbasiouny
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, OH, 45435, USA.,Department of Biomedical, Industrial, and Human Factors Engineering, College of Engineering and Computer Science, Wright State University, Dayton, OH 45435, USA
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92
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Bos R, Harris-Warrick RM, Brocard C, Demianenko LE, Manuel M, Zytnicki D, Korogod SM, Brocard F. Kv1.2 Channels Promote Nonlinear Spiking Motoneurons for Powering Up Locomotion. Cell Rep 2018; 22:3315-3327. [PMID: 29562186 PMCID: PMC5907934 DOI: 10.1016/j.celrep.2018.02.093] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/02/2018] [Accepted: 02/23/2018] [Indexed: 01/15/2023] Open
Abstract
Spinal motoneurons are endowed with nonlinear spiking behaviors manifested by a spike acceleration whose functional significance remains uncertain. Here, we show in rodent lumbar motoneurons that these nonlinear spiking properties do not rely only on activation of dendritic nifedipine-sensitive L-type Ca2+ channels, as assumed for decades, but also on the slow inactivation of a nifedipine-sensitive K+ current mediated by Kv1.2 channels that are highly expressed in axon initial segments. Specifically, the pharmacological and computational inhibition of Kv1.2 channels occluded the spike acceleration of rhythmically active motoneurons and the correlated slow buildup of rhythmic motor output recorded at the onset of locomotor-like activity. This study demonstrates that slow inactivation of Kv1.2 channels provides a potent gain control mechanism in mammalian spinal motoneurons and has a behavioral role in enhancing locomotor drive during the transition from immobility to steady-state locomotion.
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Affiliation(s)
- Rémi Bos
- Institut de Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | | | - Cécile Brocard
- Institut de Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | - Liliia E Demianenko
- Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kiev, Ukraine
| | - Marin Manuel
- Centre de Neurophysique, Physiologie et Pathologie, UMR 8119, CNRS/Université Paris Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France
| | - Daniel Zytnicki
- Centre de Neurophysique, Physiologie et Pathologie, UMR 8119, CNRS/Université Paris Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France
| | - Sergiy M Korogod
- Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kiev, Ukraine
| | - Frédéric Brocard
- Institut de Neurosciences de la Timone (UMR7289), Aix-Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France.
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93
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Selvaraj BT, Livesey MR, Chandran S. Modeling the C9ORF72 repeat expansion mutation using human induced pluripotent stem cells. Brain Pathol 2018; 27:518-524. [PMID: 28585384 PMCID: PMC8029270 DOI: 10.1111/bpa.12520] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/23/2017] [Indexed: 12/12/2022] Open
Abstract
C9ORF72 repeat expansion is the most frequent causal genetic mutation giving rise to amyotrophic lateral sclerosis (ALS) and fronto‐temporal dementia (FTD). The relatively recent discovery of the C9ORF72 repeat expansion in 2011 and the complexity of the mutation have meant that animal models that successfully recapitulate human C9ORF72 repeat expansion‐mediated disease are only now emerging. Concurrent advances in the use of patient‐derived induced pluripotent stem cells (iPSCs) to model aspects of neurological disease offers an additional approach for the study of C9ORF72 mutation. This review focuses on the opportunities of human C9ORF72 iPSC platforms to model pathological aspects of disease and how findings compare with other existing models of disease and post mortem data.
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Affiliation(s)
- Bhuvaneish T Selvaraj
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, EH16 4UU, UK.,Euan MacDonald Centre for MND Research, University of Edinburgh, Edinburgh, EH16 4SB, UK.,Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Matthew R Livesey
- Euan MacDonald Centre for MND Research, University of Edinburgh, Edinburgh, EH16 4SB, UK.,Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK.,Centre for Integrative Physiology, University of Edinburgh, EH8 9XD, UK
| | - Siddharthan Chandran
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, EH16 4UU, UK.,Euan MacDonald Centre for MND Research, University of Edinburgh, Edinburgh, EH16 4SB, UK.,Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK.,Centre for Brain Development and Repair, inStem, Bangalore, 560065, Karnataka, India
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94
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Abstract
Spinal motoneurones (Mns) constitute the final output for the execution of motor tasks. In addition to innervating muscles, Mns project excitatory collateral connections to Renshaw cells (RCs) and other Mns, but the latter have received little attention. We show that Mns receive strong synaptic input from other Mns throughout development and into maturity, with fast-type Mns systematically receiving greater recurrent excitation than slow-type Mns. Optical recordings show that activation of Mns in one spinal segment can propagate to adjacent segments even in the presence of intact recurrent inhibition. While it is known that transmission at the neuromuscular junction is purely cholinergic and RCs are excited through both acetylcholine and glutamate receptors, here we show that neurotransmission between Mns is purely glutamatergic, indicating that synaptic transmission systems are differentiated at different postsynaptic targets of Mns.
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Affiliation(s)
- Gardave S. Bhumbra
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Marco Beato
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
- * E-mail:
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95
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Brownstone RM, Lancelin C. Escape from homeostasis: spinal microcircuits and progression of amyotrophic lateral sclerosis. J Neurophysiol 2018; 119:1782-1794. [PMID: 29384454 PMCID: PMC6008087 DOI: 10.1152/jn.00331.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In amyotrophic lateral sclerosis (ALS), loss of motoneuron function leads to weakness and, ultimately, respiratory failure and death. Regardless of the initial pathogenic factors, motoneuron loss follows a specific pattern: the largest α-motoneurons die before smaller α-motoneurons, and γ-motoneurons are spared. In this article, we examine how homeostatic responses to this orderly progression could lead to local microcircuit dysfunction that in turn propagates motoneuron dysfunction and death. We first review motoneuron diversity and the principle of α-γ coactivation and then discuss two specific spinal motoneuron microcircuits: those involving proprioceptive afferents and those involving Renshaw cells. Next, we propose that the overall homeostatic response of the nervous system is aimed at maintaining force output. Thus motoneuron degeneration would lead to an increase in inputs to motoneurons, and, because of the pattern of neuronal degeneration, would result in an imbalance in local microcircuit activity that would overwhelm initial homeostatic responses. We suggest that this activity would ultimately lead to excitotoxicity of motoneurons, which would hasten the progression of disease. Finally, we propose that should this be the case, new therapies targeted toward microcircuit dysfunction could slow the course of ALS.
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Affiliation(s)
- Robert M Brownstone
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London , London , United Kingdom
| | - Camille Lancelin
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London , London , United Kingdom
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96
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Fogarty MJ, Mu EWH, Lavidis NA, Noakes PG, Bellingham MC. Motor Areas Show Altered Dendritic Structure in an Amyotrophic Lateral Sclerosis Mouse Model. Front Neurosci 2017; 11:609. [PMID: 29163013 PMCID: PMC5672020 DOI: 10.3389/fnins.2017.00609] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/18/2017] [Indexed: 12/11/2022] Open
Abstract
Objective: Motor neurons (MNs) die in amyotrophic lateral sclerosis (ALS), a clinically heterogeneous neurodegenerative disease of unknown etiology. In human or rodent studies, MN loss is preceded by increased excitability. As increased neuronal excitability correlates with structural changes in dendritic arbors and spines, we have examined longitudinal changes in dendritic structure in vulnerable neuron populations in a mouse model of familial ALS. Methods: We used a modified Golgi-Cox staining method to determine the progressive changes in dendritic structure of hippocampal CA1 pyramidal neurons, striatal medium spiny neurons, and resistant (trochlear, IV) or susceptible (hypoglossal, XII; lumbar) MNs from brainstem and spinal cord of mice over-expressing the human SOD1G93A (SOD1) mutation, in comparison to wild-type (WT) mice, at four postnatal (P) ages of 8–15, 28–35, 65–75, and 120 days. Results: In SOD1 mice, dendritic changes occur at pre-symptomatic ages in both XII and spinal cord lumbar MNs. Spine loss without dendritic changes was present in striatal neurons from disease onset. Spine density increases were present at all ages studied in SOD1 XII MNs. Spine density increased in neonatal lumbar MNs, before decreasing to control levels by P28-35 and was decreased by P120. SOD1 XII MNs and lumbar MNs, but not trochlear MNs showed vacuolization from the same time-points. Trochlear MN dendrites were unchanged. Interpretation: Dendritic structure and spine alterations correlate with the neuro-motor phenotype in ALS and with cognitive and extra-motor symptoms seen in patients. Prominent early changes in dendritic arbors and spines occur in susceptible cranial and spinal cord MNs, but are absent in MNs resistant to loss in ALS.
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Affiliation(s)
- Matthew J Fogarty
- Faculty of Medicine, School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Erica W H Mu
- Faculty of Medicine, School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Nickolas A Lavidis
- Faculty of Medicine, School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Peter G Noakes
- Faculty of Medicine, School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia.,Queensland Brain Institute, University of Queensland, St Lucia, QLD, Australia
| | - Mark C Bellingham
- Faculty of Medicine, School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
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97
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de Carvalho M, Swash M. Physiology of the fasciculation potentials in amyotrophic lateral sclerosis: which motor units fasciculate? J Physiol Sci 2017; 67:569-576. [PMID: 27638031 PMCID: PMC10717571 DOI: 10.1007/s12576-016-0484-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/05/2016] [Indexed: 10/21/2022]
Abstract
We set out to study whether in amyotrophic lateral sclerosis (ALS) fasciculation potentials (FPs) arise from the most excitable motor units (MUs). We studied 70 patients with ALS and 18 subjects with benign fasciculation syndrome (BFS). Of the 56 eligible ALS patients, 31 had signs of reinnervation in the right first dorsal interosseous muscle selected for study, and 25 did not. Two needle electrodes were placed in different MUs in each studied muscle. We defined the most excitable MU as that first activated by minimal voluntary contraction. In muscles without reinnervation, the recording site with most frequent FPs had a higher probability of showing the first recruited MU (p < 0.001). No significant difference was found in other patients or in BFS subjects. In very early affected muscles, fasciculating MUs are the most likely to be recruited volitionally. This probably represents hyperexcitability at lower motor neuronal level.
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Affiliation(s)
- Mamede de Carvalho
- Instituto de Medicina Molecular and Institute of Physiology, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
- Department of Neurosciences, Hospital de Santa Maria-CHLN, Av. Professor Egas Moniz, 1648-028, Lisbon, Portugal.
| | - Michael Swash
- Instituto de Medicina Molecular and Institute of Physiology, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Departments of Neurology and Neuroscience, Barts and the London School of Medicine, Queen Mary University of London, London, UK
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98
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Changes in the Excitability of Neocortical Neurons in a Mouse Model of Amyotrophic Lateral Sclerosis Are Not Specific to Corticospinal Neurons and Are Modulated by Advancing Disease. J Neurosci 2017; 37:9037-9053. [PMID: 28821643 PMCID: PMC5597984 DOI: 10.1523/jneurosci.0811-17.2017] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/22/2017] [Accepted: 08/06/2017] [Indexed: 12/13/2022] Open
Abstract
Cell type-specific changes in neuronal excitability have been proposed to contribute to the selective degeneration of corticospinal neurons in amyotrophic lateral sclerosis (ALS) and to neocortical hyperexcitability, a prominent feature of both inherited and sporadic variants of the disease, but the mechanisms underlying selective loss of specific cell types in ALS are not known. We analyzed the physiological properties of distinct classes of cortical neurons in the motor cortex of hSOD1G93A mice of both sexes and found that they all exhibit increases in intrinsic excitability that depend on disease stage. Targeted recordings and in vivo calcium imaging further revealed that neurons adapt their functional properties to normalize cortical excitability as the disease progresses. Although different neuron classes all exhibited increases in intrinsic excitability, transcriptional profiling indicated that the molecular mechanisms underlying these changes are cell type specific. The increases in excitability in both excitatory and inhibitory cortical neurons show that selective dysfunction of neuronal cell types cannot account for the specific vulnerability of corticospinal motor neurons in ALS. Furthermore, the stage-dependent alterations in neuronal function highlight the ability of cortical circuits to adapt as disease progresses. These findings show that both disease stage and cell type must be considered when developing therapeutic strategies for treating ALS.SIGNIFICANCE STATEMENT It is not known why certain classes of neurons preferentially die in different neurodegenerative diseases. It has been proposed that the enhanced excitability of affected neurons is a major contributor to their selective loss. We show using a mouse model of amyotrophic lateral sclerosis (ALS), a disease in which corticospinal neurons exhibit selective vulnerability, that changes in excitability are not restricted to this neuronal class and that excitability does not increase monotonically with disease progression. Moreover, although all neuronal cell types tested exhibited abnormal functional properties, analysis of their gene expression demonstrated cell type-specific responses to the ALS-causing mutation. These findings suggest that therapies for ALS may need to be tailored for different cell types and stages of disease.
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99
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Opposite Synaptic Alterations at the Neuromuscular Junction in an ALS Mouse Model: When Motor Units Matter. J Neurosci 2017; 37:8901-8918. [PMID: 28821658 DOI: 10.1523/jneurosci.3090-16.2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 06/29/2017] [Accepted: 08/02/2017] [Indexed: 12/13/2022] Open
Abstract
Denervation of the neuromuscular junction (NMJ) precedes the loss of motor neurons (MNs) in amyotrophic lateral sclerosis (ALS). ALS is characterized by a motor unit (MU)-dependent vulnerability where MNs with fast-fatigable (FF) characteristics are lost first, followed by fast fatigue-resistant (FR) and slow (S) MNs. However, changes in NMJ properties as a function of MU types remain debated. We hypothesized that NMJ synaptic functions would be altered precociously in an MU-specific manner, before structural alterations of the NMJ. Synaptic transmission and morphological changes of NMJs have been explored in two nerve-muscle preparations of male SOD1G37R mice and their wild-type (WT) littermates: the soleus (S and FR MU); and the extensor digitorum longus (FF MU). S, FR, and FF NMJs of WT mice showed distinct synaptic properties from which we build an MU synaptic profile (MUSP) that reports MU-dependent NMJ synaptic properties. At postnatal day 180 (P180), FF and S NMJs of SOD1 already showed, respectively, lower and higher quantal content compared with WT mice, before signs of MN death and before NMJ morphological alterations. Changes persisted in both muscles until preonset (P380), while denervation was frequent in the mutant mouse. MN death was evident at this stage. Additional changes occurred at clinical disease onset (P450) for S and FR MU. As a whole, our results reveal a reversed MUSP in SOD1 mutants and highlight MU-specific synaptic changes occurring in a precise temporal sequence. Importantly, changes in synaptic properties appear to be good predictors of vulnerability to neurodegeneration.SIGNIFICANCE STATEMENT The inadequate excitability of motor neurons and their output, the neuromuscular junctions (NMJs), has been considered a key factor in the detrimental outcome of the motor function in amyotrophic lateral sclerosis. However, a conundrum persists at the NMJ whereby persistent but incoherent opposite neurotransmission changes have been reported to take place. This article untangles this conundrum by systematically analyzing the changes in synaptic properties over the course of the disease progression as a function of the motor unit type. This temporal analysis reveals that early synaptic alterations evolve with disease progression but precede NMJ neurodegeneration. These data provide a novel framework of analysis and comparison of synaptic transmission alterations in neurodegenerative disorders.
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100
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Selective Motor Neuron Resistance and Recovery in a New Inducible Mouse Model of TDP-43 Proteinopathy. J Neurosci 2017; 36:7707-17. [PMID: 27445147 DOI: 10.1523/jneurosci.1457-16.2016] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 06/09/2016] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Motor neurons (MNs) are the neuronal class that is principally affected in amyotrophic lateral sclerosis (ALS), but it is widely known that individual motor pools do not succumb to degeneration simultaneously. Because >90% of ALS patients have an accumulation of cytoplasmic TDP-43 aggregates in postmortem brain and spinal cord (SC), it has been suggested that these inclusions in a given population may trigger its death. We investigated seven MN pools in our new inducible rNLS8 transgenic (Tg) mouse model of TDP-43 proteinopathy and found striking differences in MN responses to TDP-43 pathology. Despite widespread neuronal expression of cytoplasmic human TDP-43, only MNs in the hypoglossal nucleus and the SC are lost after 8 weeks of transgene expression, whereas those in the oculomotor, trigeminal, and facial nuclei are spared. Within the SC, slow MNs survive to end stage, whereas fast fatigable MNs are lost. Correspondingly, axonal dieback occurs first from fast-twitch muscle fibers, whereas slow-twitch fibers remain innervated. Individual pools show differences in the downregulation of endogenous nuclear TDP-43, but this does not fully account for vulnerability to degenerate. After transgene suppression, resistant MNs sprout collaterals to reinnervate previously denervated neuromuscular junctions concurrently with expression of matrix metalloproteinase 9 (MMP-9), a marker of fast MNs. Therefore, although pathological TDP-43 is linked to MN degeneration, the process is not stochastic and mirrors the highly selective patterns of MN degeneration observed in ALS patients. SIGNIFICANCE STATEMENT Because TDP-43 is the major pathological hallmark of amyotrophic lateral sclerosis (ALS), we generated mice in which mutant human TDP-43 expression causes progressive neuron loss. We show that these rNLS8 mice have a pattern of axonal dieback and cell death that mirrors that often observed in human patients. This finding demonstrates the diversity of motor neuron (MN) populations in their response to pathological TDP-43. Furthermore, we demonstrate that resistant MNs are able to compensate for the loss of their more vulnerable counterparts and change their phenotype in the process. These findings are important because using a mouse model that closely models human ALS in both the disease pathology and the pattern of degeneration is critical to studying and eventually treating progressive paralysis in ALS patients.
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