251
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Lorenz C, Jones KE. IH activity is increased in populations of slow versus fast motor axons of the rat. Front Hum Neurosci 2014; 8:766. [PMID: 25309406 PMCID: PMC4174588 DOI: 10.3389/fnhum.2014.00766] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/10/2014] [Indexed: 11/25/2022] Open
Abstract
Much is known about the electrophysiological variation in motoneuron somata across different motor units. However, comparatively less is known about electrophysiological variation in motor axons and how this could impact function or electrodiagnosis in healthy or diseased states. We performed nerve excitability testing on two groups of motor axons in Sprague–Dawley rats that are known to differ significantly in their chronic daily activity patterns and in the relative proportion of motor unit types: one group innervating the soleus (“slow motor axons”) and the other group innervating the tibialis anterior (“fast motor axons”) muscles. We found that slow motor axons have significantly larger accommodation compared to fast motor axons upon application of a 100 ms hyperpolarizing conditioning stimulus that is 40% of axon threshold (Z = 3.24, p = 0.001) or 20% of axon threshold (Z = 2.67, p = 0.008). Slow motor axons had larger accommodation to hyperpolarizing currents in the current-threshold measurement (-80% Z = 3.07, p = 0.002; -90% Z = 2.98, p = 0.003). In addition, we found that slow motor axons have a significantly smaller rheobase than fast motor axons (Z = -1.99, p = 0.047) accompanied by a lower threshold in stimulus-response curves. The results provide evidence that slow motor axons have greater activity of the hyperpolarization-activated inwardly rectifying cation conductance (IH) than fast motor axons. It is possible that this difference between fast and slow axons is caused by an adaptation to their chronic differences in daily activity patterns, and that this adaptation might have a functional effect on the motor unit. Moreover, these findings indicate that slow and fast motor axons may react differently to pathological conditions.
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Affiliation(s)
- Chad Lorenz
- Faculty of Physical Education and Recreation, University of Alberta Edmonton, AB, Canada
| | - Kelvin E Jones
- Faculty of Physical Education and Recreation, University of Alberta Edmonton, AB, Canada ; Neuroscience and Mental Health Institute, University of Alberta Edmonton, AB, Canada
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252
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Formation of cholinergic synapse-like specializations at developing murine muscle spindles. Dev Biol 2014; 393:227-235. [DOI: 10.1016/j.ydbio.2014.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 12/30/2022]
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253
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Modeling motor neuron disease: the matter of time. Trends Neurosci 2014; 37:642-52. [PMID: 25156326 DOI: 10.1016/j.tins.2014.07.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 07/11/2014] [Accepted: 07/25/2014] [Indexed: 12/12/2022]
Abstract
Stem cell technologies have created new opportunities to generate unlimited numbers of human neurons in the lab and study neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Although some disease hallmarks have been reported in patient-derived stem cell models, it is proving more difficult to recapitulate the full phenotypic extent of these disorders. The problem with these stem cell models lies in the disparity between the advanced age of onset of neurodegenerative disorders and the embryonic nature of the in vitro derived cell types. In this review we discuss experimental methods of in vitro aging of neural cell types as a means to elicit late-onset symptoms in induced pluripotent stem cell (iPSC) models of neurodegenerative disease.
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254
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Abstract
To explore the link between bioenergetics and motor neuron degeneration, we used a computational model in which detailed morphology and ion conductance are paired with intracellular ATP production and consumption. We found that reduced ATP availability increases the metabolic cost of a single action potential and disrupts K+/Na+ homeostasis, resulting in a chronic depolarization. The magnitude of the ATP shortage at which this ionic instability occurs depends on the morphology and intrinsic conductance characteristic of the neuron. If ATP shortage is confined to the distal part of the axon, the ensuing local ionic instability eventually spreads to the whole neuron and involves fasciculation-like spiking events. A shortage of ATP also causes a rise in intracellular calcium. Our modeling work supports the notion that mitochondrial dysfunction can account for salient features of the paralytic disorder amyotrophic lateral sclerosis, including motor neuron hyperexcitability, fasciculation, and differential vulnerability of motor neuron subpopulations.
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Affiliation(s)
- Gwendal Le Masson
- Neurocentre Magendie, INSERM U862, University of Bordeaux, 33077 Bordeaux, France; Department of Neurology, Neuro-Muscular Unit and ALS Center, CHU de Bordeaux, 33076 Bordeaux, France.
| | - Serge Przedborski
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032-3784, USA; Departments of Neurology, Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
| | - L F Abbott
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032-3784, USA; Departments of Neuroscience and Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
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255
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Plasticity versus specificity in RTK signalling modalities for distinct biological outcomes in motor neurons. BMC Biol 2014; 12:56. [PMID: 25124859 PMCID: PMC4169644 DOI: 10.1186/s12915-014-0056-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/04/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Multiple growth factors are known to control several aspects of neuronal biology, consecutively acting as morphogens to diversify neuronal fates, as guidance cues for axonal growth, and as modulators of survival or death to regulate neuronal numbers. The multiplicity of neuronal types is permitted by the combinatorial usage of growth factor receptors, each of which is expressed in distinct and overlapping subsets of neurons, and by the multitasking role of growth factor receptors, which recruit multiple signalling cascades differentially required for distinct biological outcomes. We have explored signalling robustness in cells where a given receptor tyrosine kinase (RTK) elicits qualitatively distinct outcomes. As the HGF/Met system regulates several biological responses in motor neurons (MN) during neuromuscular development, we have investigated the signalling modalities through which the HGF/Met system impacts on MN biology, and the degree of robustness of each of these functions, when challenged with substitutions of signalling pathways. RESULTS Using a set of mouse lines carrying signalling mutations that change the Met phosphotyrosine binding preferences, we have asked whether distinct functions of Met in several MN subtypes require specific signalling pathways, and to which extent signalling plasticity allows a pleiotropic system to exert distinct developmental outcomes. The differential ability of signalling mutants to promote muscle migration versus axonal growth allowed us to uncouple an indirect effect of HGF/Met signalling on nerve growth through the regulation of muscle size from a direct regulation of motor growth via the PI3 kinase (PI3K), but not Src kinase, pathway. Furthermore, we found that HGF/Met-triggered expansion of Pea3 expression domain in the spinal cord can be accomplished through several alternative signalling cascades, differentially sensitive to the Pea3 dosage. Finally, we show that the regulation of MN survival by HGF/Met can equally be achieved in vitro and in vivo by alternative signalling cascades involving either PI3K-Akt or Src and Mek pathways. CONCLUSIONS Our findings distinguish MN survival and fate specification, as RTK-triggered responses allowing substitutions of the downstream signalling routes, from nerve growth patterning, which depends on a selective, non-substitutable pathway.
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256
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Cerebrospinal fluid-targeted delivery of neutralizing anti-IFNγ antibody delays motor decline in an ALS mouse model. Neuroreport 2014; 25:49-54. [PMID: 24145774 DOI: 10.1097/wnr.0000000000000043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterized by the selective and gradual loss of motoneurons in the brain and spinal cord. A persistent inflammation, typified by the activation of astrocytes and microglia, accompanies the progressive degeneration of motoneurons. Interferon gamma (IFNγ), a potent proinflammatory cytokine that is aberrantly present in the spinal cord of ALS mice and patients, has been proposed to contribute to motoneuron death by eliciting the activation of the lymphotoxin-β receptor (LT-βR) through its ligand LIGHT. However, the implication of IFNγ in the pathogenic process remains elusive. Here, we show that an antagonistic anti-IFNγ antibody efficiently rescues motoneurons from IFNγ-induced death. When transiently delivered in the cerebrospinal fluid through a subcutaneously implanted osmotic minipump, the neutralizing anti-IFNγ antibody significantly retarded motor function decline in a mouse model of ALS. However, this transient infusion of anti-IFNγ antibody did not increase the life expectancy of ALS mice. Our results suggest that IFNγ contributes to ALS pathogenesis and represents a potential therapeutic target for ALS.
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257
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Herrera FJ, Yamaguchi T, Roelink H, Tjian R. Core promoter factor TAF9B regulates neuronal gene expression. eLife 2014; 3:e02559. [PMID: 25006164 PMCID: PMC4083437 DOI: 10.7554/elife.02559] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Emerging evidence points to an unexpected diversification of core promoter recognition complexes that serve as important regulators of cell-type specific gene transcription. Here, we report that the orphan TBP-associated factor TAF9B is selectively up-regulated upon in vitro motor neuron differentiation, and is required for the transcriptional induction of specific neuronal genes, while dispensable for global gene expression in murine ES cells. TAF9B binds to both promoters and distal enhancers of neuronal genes, partially co-localizing at binding sites of OLIG2, a key activator of motor neuron differentiation. Surprisingly, in this neuronal context TAF9B becomes preferentially associated with PCAF rather than the canonical TFIID complex. Analysis of dissected spinal column from Taf9b KO mice confirmed that TAF9B also regulates neuronal gene transcription in vivo. Our findings suggest that alternative core promoter complexes may provide a key mechanism to lock in and maintain specific transcriptional programs in terminally differentiated cell types. DOI:http://dx.doi.org/10.7554/eLife.02559.001 Almost all the cells in an organism contain the same genetic information, but they develop into many different types of cells that perform a variety of specialized functions in the body. Brain cells, for example, have a very different shape and function from red blood cells. A small group of proteins act inside cells to switch on the expression of genes it needs to carry out the specific functions of a given cell-type, and switch off the genes that are only needed in other cell types. Some of these regulatory proteins called ‘core promoter factors’ bind to the DNA near the start of genes. These core factors are known to work in combination with various other proteins to switch genes on or off in specific cell types. However, the specific core promoter factors and partner proteins that guide a cell into becoming a neuron have not been well characterized. Now, Herrera et al. have identified a core promoter factor called TAF9B that is produced at higher levels when mouse stem cells are coaxed into becoming the motor neurons that carry nerve impulses to muscles. The TAF9B protein works together with an enzyme (called PCAF) to help to switch on the genes that control the development of these cells. Without this regulatory protein, mouse stem cells grown in the lab fail to properly switch on the genes that are necessary to become motor neurons. These mutant stem cells also fail to efficiently switch off genes that stop stem cells from becoming more specialized. High levels of TAF9B were also found in the spinal cord of newborn mice and when Herrera et al. engineered mice that lack TAF9B, these mice did not properly regulate the expression of neuronal genes in their spines. These new findings might, in the future, improve our ability to guide stem cells into forming neurons, or to reprogram other types of specialized cells into becoming motor neurons. This new information could also prove useful for researchers interested in better understanding neuronal development and might aid in the design of therapies to treat neuronal injuries or diseases, such as motor neuron disease. DOI:http://dx.doi.org/10.7554/eLife.02559.002
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Affiliation(s)
- Francisco J Herrera
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States CIRM Center of Excellence, Li Ka Shing Center For Biomedical and Health Sciences, University of California, Berkeley, Berkeley, United States
| | - Teppei Yamaguchi
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States CIRM Center of Excellence, Li Ka Shing Center For Biomedical and Health Sciences, University of California, Berkeley, Berkeley, United States
| | - Henk Roelink
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Robert Tjian
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States CIRM Center of Excellence, Li Ka Shing Center For Biomedical and Health Sciences, University of California, Berkeley, Berkeley, United States
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258
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Mohan R, Tosolini AP, Morris R. Targeting the motor end plates in the mouse hindlimb gives access to a greater number of spinal cord motor neurons: an approach to maximize retrograde transport. Neuroscience 2014; 274:318-30. [PMID: 24892760 DOI: 10.1016/j.neuroscience.2014.05.045] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/05/2014] [Accepted: 05/21/2014] [Indexed: 11/15/2022]
Abstract
Lower motor neuron dysfunction is one of the most debilitating neurological conditions and, as such, significantly impacts on the quality of life of affected individuals. Within the last decade, the engineering of mouse models of lower motor neuron diseases has facilitated the development of new therapeutic scenarios aimed at delaying or reversing the progression of these conditions. In this context, motor end plates (MEPs) are highly specialized regions on the skeletal musculature that offer minimally invasive access to the pre-synaptic nerve terminals, henceforth to the spinal cord motor neurons. Transgenic technologies can take advantage of the relationship between the MEP regions on the skeletal muscles and the corresponding motor neurons to shuttle therapeutic genes into specific compartments within the ventral horn of the spinal cord. The first aim of this neuroanatomical investigation was to map the details of the organization of the MEP zones for the main muscles of the mouse hindlimb. The hindlimb was selected for the present work, as it is currently a common target to challenge the efficacy of therapies aimed at alleviating neuromuscular dysfunction. This MEP map was then used to guide series of intramuscular injections of Fluoro-Gold (FG) along the muscles' MEP zones, therefore revealing the distribution of the motor neurons that supply them. Targeting the entire MEP regions with FG increased the somatic availability of the retrograde tracer and, consequently, gave rise to FG-positive motor neurons that are organized into rostro-caudal columns spanning more spinal cord segments than previously reported. The results of this investigation will have positive implications for future studies involving the somatic delivery and retrograde transport of therapeutic transgenes into affected motor neurons. These data will also provide a framework for transgenic technologies aiming at maintaining the integrity of the neuromuscular junction for the treatment of lower motor neuron dysfunctions.
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Affiliation(s)
- R Mohan
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - A P Tosolini
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - R Morris
- Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia.
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259
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Ang CE, Wernig M. Induced neuronal reprogramming. J Comp Neurol 2014; 522:2877-86. [PMID: 24771471 DOI: 10.1002/cne.23620] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 04/24/2014] [Accepted: 04/25/2014] [Indexed: 12/21/2022]
Abstract
Cellular differentiation processes during normal embryonic development are guided by extracellular soluble factors such as morphogen gradients and cell contact signals, eventually resulting in induction of specific combinations of lineage-determining transcription factors. The young field of epigenetic reprogramming takes advantage of this knowledge and uses cell fate determination factors to convert one lineage into another such as the conversion of fibroblasts into pluripotent stem cells or neurons. These induced cell fate conversions open up new avenues for studying disease processes, generating cell material for therapeutic intervention such as drug screening and potentially also for cell-based therapies. However, there are still limitations that have to be overcome to fulfill these promises, centering on reprogramming efficiencies, cell identity, and maturation. In this review, we discuss the discovery of induced neuronal reprogramming, ways to improve the conversion process, and finally how to define properly the identity of those converted neuronal cells.
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Affiliation(s)
- Cheen Euong Ang
- Institute for Stem Cell Biology and Regenerative Medicine and Department of Pathology, Stanford University School of Medicine, Stanford, California, 94305; Department of Bioengineering, Stanford University School of Medicine, Stanford, California, 94305
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260
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Gallart-Palau X, Tarabal O, Casanovas A, Sábado J, Correa FJ, Hereu M, Piedrafita L, Calderó J, Esquerda JE. Neuregulin-1 is concentrated in the postsynaptic subsurface cistern of C-bouton inputs to α-motoneurons and altered during motoneuron diseases. FASEB J 2014; 28:3618-32. [PMID: 24803543 DOI: 10.1096/fj.13-248583] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
C boutons are large, cholinergic, synaptic terminals that arise from local interneurons and specifically contact spinal α-motoneurons (MNs). C boutons characteristically display a postsynaptic specialization consisting of an endoplasmic reticulum-related subsurface cistern (SSC) of unknown function. In the present work, by using confocal microscopy and ultrastructural immunolabeling, we demonstrate that neuregulin-1 (NRG1) accumulates in the SSC of mouse spinal MNs. We also show that the NRG1 receptors erbB2 and erbB4 are presynaptically localized within C boutons, suggesting that NRG1-based retrograde signaling may occur in this type of synapse. In most of the cranial nuclei, MNs display the same pattern of NRG1 distribution as that observed in spinal cord MNs. Conversely, MNs in oculomotor nuclei, which are spared in amyotrophic lateral sclerosis (ALS), lack both C boutons and SSC-associated NRG1. NRG1 in spinal MNs is developmentally regulated and depends on the maintenance of nerve-muscle interactions, as we show after nerve transection experiments. Changes in NRG1 in C boutons were also investigated in mouse models of MN diseases: i.e., spinal muscular atrophy (SMNΔ7) and ALS (SOD1(G93A)). In both models, a transient increase in NRG1 in C boutons occurs during disease progression. These data increase our understanding of the role of C boutons in MN physiology and pathology.
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Affiliation(s)
- Xavier Gallart-Palau
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Olga Tarabal
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Anna Casanovas
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Javier Sábado
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Francisco J Correa
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Marta Hereu
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Lídia Piedrafita
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Jordi Calderó
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
| | - Josep E Esquerda
- Unitat de Neurobiologia Cellular, Departament de Medicina Experimental, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Universitat de Lleida, Lleida, Catalonia, Spain
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261
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Babin PJ, Goizet C, Raldúa D. Zebrafish models of human motor neuron diseases: advantages and limitations. Prog Neurobiol 2014; 118:36-58. [PMID: 24705136 DOI: 10.1016/j.pneurobio.2014.03.001] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/11/2014] [Accepted: 03/14/2014] [Indexed: 01/08/2023]
Abstract
Motor neuron diseases (MNDs) are an etiologically heterogeneous group of disorders of neurodegenerative origin, which result in degeneration of lower (LMNs) and/or upper motor neurons (UMNs). Neurodegenerative MNDs include pure hereditary spastic paraplegia (HSP), which involves specific degeneration of UMNs, leading to progressive spasticity of the lower limbs. In contrast, spinal muscular atrophy (SMA) involves the specific degeneration of LMNs, with symmetrical muscle weakness and atrophy. Amyotrophic lateral sclerosis (ALS), the most common adult-onset MND, is characterized by the degeneration of both UMNs and LMNs, leading to progressive muscle weakness, atrophy, and spasticity. A review of the comparative neuroanatomy of the human and zebrafish motor systems showed that, while the zebrafish was a homologous model for LMN disorders, such as SMA, it was only partially relevant in the case of UMN disorders, due to the absence of corticospinal and rubrospinal tracts in its central nervous system. Even considering the limitation of this model to fully reproduce the human UMN disorders, zebrafish offer an excellent alternative vertebrate model for the molecular and genetic dissection of MND mechanisms. Its advantages include the conservation of genome and physiological processes and applicable in vivo tools, including easy imaging, loss or gain of function methods, behavioral tests to examine changes in motor activity, and the ease of simultaneous chemical/drug testing on large numbers of animals. This facilitates the assessment of the environmental origin of MNDs, alone or in combination with genetic traits and putative modifier genes. Positive hits obtained by phenotype-based small-molecule screening using zebrafish may potentially be effective drugs for treatment of human MNDs.
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Affiliation(s)
- Patrick J Babin
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France.
| | - Cyril Goizet
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France; CHU Bordeaux, Hôpital Pellegrin, Service de Génétique Médicale, Bordeaux, France
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262
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Arnold AS, Gill J, Christe M, Ruiz R, McGuirk S, St-Pierre J, Tabares L, Handschin C. Morphological and functional remodelling of the neuromuscular junction by skeletal muscle PGC-1α. Nat Commun 2014; 5:3569. [PMID: 24686533 PMCID: PMC4846352 DOI: 10.1038/ncomms4569] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 03/06/2014] [Indexed: 11/09/2022] Open
Abstract
The neuromuscular junction (NMJ) exhibits high morphological and functional plasticity. In the mature muscle, the relative levels of physical activity are the major determinants of NMJ function. Classically, motor neuron-mediated activation patterns of skeletal muscle have been thought of as the major drivers of NMJ plasticity and the ensuing fibre-type determination in muscle. Here we use muscle-specific transgenic animals for the peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) as a genetic model for trained mice to elucidate the contribution of skeletal muscle to activity-induced adaptation of the NMJ. We find that muscle-specific expression of PGC-1α promotes a remodelling of the NMJ, even in the absence of increased physical activity. Importantly, these plastic changes are not restricted to post-synaptic structures, but extended to modulation of presynaptic cell morphology and function. Therefore, our data indicate that skeletal muscle significantly contributes to the adaptation of the NMJ subsequent to physical activity.
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Affiliation(s)
- Anne-Sophie Arnold
- Biozentrum, Division of Pharmacology/Neurobiology, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - Jonathan Gill
- Biozentrum, Division of Pharmacology/Neurobiology, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - Martine Christe
- 1] Biozentrum, Division of Pharmacology/Neurobiology, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland [2]
| | - Rocío Ruiz
- Department of Medical Physiology and Biophysics, School of Medicine University of Seville, Avda. Sánchez Pizjuan 4, 41009 Sevilla, Spain
| | - Shawn McGuirk
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, 3655 promenade Sir William Osler, Montreal, Quebec, Canada H3G 1Y6
| | - Julie St-Pierre
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, 3655 promenade Sir William Osler, Montreal, Quebec, Canada H3G 1Y6
| | - Lucía Tabares
- Department of Medical Physiology and Biophysics, School of Medicine University of Seville, Avda. Sánchez Pizjuan 4, 41009 Sevilla, Spain
| | - Christoph Handschin
- Biozentrum, Division of Pharmacology/Neurobiology, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
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263
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Müller D, Cherukuri P, Henningfeld K, Poh CH, Wittler L, Grote P, Schlüter O, Schmidt J, Laborda J, Bauer SR, Brownstone RM, Marquardt T. Dlk1 promotes a fast motor neuron biophysical signature required for peak force execution. Science 2014; 343:1264-6. [PMID: 24626931 DOI: 10.1126/science.1246448] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Motor neurons, which relay neural commands to drive skeletal muscle movements, encompass types ranging from "slow" to "fast," whose biophysical properties govern the timing, gradation, and amplitude of muscle force. Here we identify the noncanonical Notch ligand Delta-like homolog 1 (Dlk1) as a determinant of motor neuron functional diversification. Dlk1, expressed by ~30% of motor neurons, is necessary and sufficient to promote a fast biophysical signature in the mouse and chick. Dlk1 suppresses Notch signaling and activates expression of the K(+) channel subunit Kcng4 to modulate delayed-rectifier currents. Dlk1 inactivation comprehensively shifts motor neurons toward slow biophysical and transcriptome signatures, while abolishing peak force outputs. Our findings provide insights into the development of motor neuron functional diversity and its contribution to the execution of movements.
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Affiliation(s)
- Daniel Müller
- Developmental Neurobiology Laboratory, European Neuroscience Institute (ENI-G), Grisebachstraße 5, 37077 Göttingen, Germany
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264
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Neuronal matrix metalloproteinase-9 is a determinant of selective neurodegeneration. Neuron 2014; 81:333-48. [PMID: 24462097 DOI: 10.1016/j.neuron.2013.12.009] [Citation(s) in RCA: 222] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2013] [Indexed: 11/24/2022]
Abstract
Selective neuronal loss is the hallmark of neurodegenerative diseases. In patients with amyotrophic lateral sclerosis (ALS), most motor neurons die but those innervating extraocular, pelvic sphincter, and slow limb muscles exhibit selective resistance. We identified 18 genes that show >10-fold differential expression between resistant and vulnerable motor neurons. One of these, matrix metalloproteinase-9 (MMP-9), is expressed only by fast motor neurons, which are selectively vulnerable. In ALS model mice expressing mutant superoxide dismutase (SOD1), reduction of MMP-9 function using gene ablation, viral gene therapy, or pharmacological inhibition significantly delayed muscle denervation. In the presence of mutant SOD1, MMP-9 expressed by fast motor neurons themselves enhances activation of ER stress and is sufficient to trigger axonal die-back. These findings define MMP-9 as a candidate therapeutic target for ALS. The molecular basis of neuronal diversity thus provides significant insights into mechanisms of selective vulnerability to neurodegeneration.
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265
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Abstract
All muscle movements, including breathing, walking, and fine motor skills rely on the function of the spinal motor neuron to transmit signals from the brain to individual muscle groups. Loss of spinal motor neuron function underlies several neurological disorders for which treatment has been hampered by the inability to obtain sufficient quantities of primary motor neurons to perform mechanistic studies or drug screens. Progress towards overcoming this challenge has been achieved through the synthesis of developmental biology paradigms and advances in stem cell and reprogramming technology, which allow the production of motor neurons in vitro. In this Primer, we discuss how the logic of spinal motor neuron development has been applied to allow generation of motor neurons either from pluripotent stem cells by directed differentiation and transcriptional programming, or from somatic cells by direct lineage conversion. Finally, we discuss methods to evaluate the molecular and functional properties of motor neurons generated through each of these techniques.
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Affiliation(s)
- Brandi N Davis-Dusenbery
- Harvard Stem Cell Institute, Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
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266
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7,8-Dihydroxyflavone improves motor performance and enhances lower motor neuronal survival in a mouse model of amyotrophic lateral sclerosis. Neurosci Lett 2014; 566:286-91. [PMID: 24637017 DOI: 10.1016/j.neulet.2014.02.058] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 02/13/2014] [Accepted: 02/26/2014] [Indexed: 02/07/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is an enigmatic neurodegenerative disorder without any effective treatment characterized by loss of motor neurons (MNs) that results in rapidly progressive motor weakness and early death due to respiratory failure. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family known to play a prominent role in the differentiation and survival of MNs. The flavonoid 7,8-dihydroxyflavone (7,8-DHF) is a potent and selective small molecule tyrosine kinase receptor B (TrkB) agonist that mimics the effects of BDNF. In the present study, we evaluated the neuroprotective effects of 7,8-DHF in a transgenic ALS mouse model (SOD1(G93A)). We found that chronic administration of 7,8-DHF significantly improved motor deficits, and preserved spinal MNs count and dendritic spines in SOD1(G93A) mice. These data suggest that 7,8-DHF should be considered as a potential therapy for ALS and the other motor neuron diseases.
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267
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Francius C, Clotman F. Generating spinal motor neuron diversity: a long quest for neuronal identity. Cell Mol Life Sci 2014; 71:813-29. [PMID: 23765105 PMCID: PMC11113339 DOI: 10.1007/s00018-013-1398-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/30/2013] [Accepted: 05/31/2013] [Indexed: 03/26/2023]
Abstract
Understanding how thousands of different neuronal types are generated in the CNS constitutes a major challenge for developmental neurobiologists and is a prerequisite before considering cell or gene therapies of nervous lesions or pathologies. During embryonic development, spinal motor neurons (MNs) segregate into distinct subpopulations that display specific characteristics and properties including molecular identity, migration pattern, allocation to specific motor columns, and innervation of defined target. Because of the facility to correlate these different characteristics, the diversification of spinal MNs has become the model of choice for studying the molecular and cellular mechanisms underlying the generation of multiple neuronal populations in the developing CNS. Therefore, how spinal motor neuron subpopulations are produced during development has been extensively studied during the last two decades. In this review article, we will provide a comprehensive overview of the genetic and molecular mechanisms that contribute to the diversification of spinal MNs.
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Affiliation(s)
- Cédric Francius
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, 55 Avenue Hippocrate, Box (B1.55.11), 1200 Brussels, Belgium
| | - Frédéric Clotman
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, 55 Avenue Hippocrate, Box (B1.55.11), 1200 Brussels, Belgium
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268
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Tang H, Inoki K, Lee M, Wright E, Khuong A, Khuong A, Sugiarto S, Garner M, Paik J, DePinho RA, Goldman D, Guan KL, Shrager JB. mTORC1 promotes denervation-induced muscle atrophy through a mechanism involving the activation of FoxO and E3 ubiquitin ligases. Sci Signal 2014; 7:ra18. [PMID: 24570486 DOI: 10.1126/scisignal.2004809] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Skeletal muscle mass and function are regulated by motor innervation, and denervation results in muscle atrophy. The activity of mammalian target of rapamycin complex 1 (mTORC1) is substantially increased in denervated muscle, but its regulatory role in denervation-induced atrophy remains unclear. At early stages after denervation of skeletal muscle, a pathway involving class II histone deacetylases and the transcription factor myogenin mediates denervation-induced muscle atrophy. We found that at later stages after denervation of fast-twitch muscle, activation of mTORC1 contributed to atrophy and that denervation-induced atrophy was mitigated by inhibition of mTORC1 with rapamycin. Activation of mTORC1 through genetic deletion of its inhibitor TSC1 (tuberous sclerosis complex 1) sensitized mice to denervation-induced muscle atrophy and suppressed the kinase activity of Akt, leading to activation of FoxO transcription factors and increasing the expression of genes encoding E3 ubiquitin ligases atrogin [also known as MAFbx (muscle atrophy F-box protein)] and MuRF1 (muscle-specific ring finger 1). Rapamycin treatment of mice restored Akt activity, suggesting that the denervation-induced increase in mTORC1 activity was producing feedback inhibition of Akt. Genetic deletion of the three FoxO isoforms in skeletal muscle induced muscle hypertrophy and abolished the late-stage induction of E3 ubiquitin ligases after denervation, thereby preventing denervation-induced atrophy. These data revealed that mTORC1, which is generally considered to be an important component of anabolism, is central to muscle catabolism and atrophy after denervation. This mTORC1-FoxO axis represents a potential therapeutic target in neurogenic muscle atrophy.
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Affiliation(s)
- Huibin Tang
- 1Division of Thoracic Surgery, Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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269
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Amamoto R, Arlotta P. Development-inspired reprogramming of the mammalian central nervous system. Science 2014; 343:1239882. [PMID: 24482482 DOI: 10.1126/science.1239882] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In 2012, John Gurdon and Shinya Yamanaka shared the Nobel Prize for the demonstration that the identity of differentiated cells is not irreversibly determined but can be changed back to a pluripotent state under appropriate instructive signals. The principle that differentiated cells can revert to an embryonic state and even be converted directly from one cell type into another not only turns fundamental principles of development on their heads but also has profound implications for regenerative medicine. Replacement of diseased tissue with newly reprogrammed cells and modeling of human disease are concrete opportunities. Here, we focus on the central nervous system to consider whether and how reprogramming of cell identity may affect regeneration and modeling of a system historically considered immutable and hardwired.
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Affiliation(s)
- Ryoji Amamoto
- Department of Stem Cell and Regenerative Biology, Sherman Fairchild Building, 7 Divinity Avenue, Harvard University, Cambridge, MA 02138, USA
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270
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Re DB, Le Verche V, Yu C, Amoroso MW, Politi KA, Phani S, Ikiz B, Hoffmann L, Koolen M, Nagata T, Papadimitriou D, Nagy P, Mitsumoto H, Kariya S, Wichterle H, Henderson CE, Przedborski S. Necroptosis drives motor neuron death in models of both sporadic and familial ALS. Neuron 2014; 81:1001-1008. [PMID: 24508385 DOI: 10.1016/j.neuron.2014.01.011] [Citation(s) in RCA: 305] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/24/2013] [Indexed: 12/15/2022]
Abstract
Most cases of neurodegenerative diseases are sporadic, hindering the use of genetic mouse models to analyze disease mechanisms. Focusing on the motor neuron (MN) disease amyotrophic lateral sclerosis (ALS), we therefore devised a fully humanized coculture model composed of human adult primary sporadic ALS (sALS) astrocytes and human embryonic stem-cell-derived MNs. The model reproduces the cardinal features of human ALS: sALS astrocytes, but not those from control patients, trigger selective death of MNs. The mechanisms underlying this non-cell-autonomous toxicity were investigated in both astrocytes and MNs. Although causal in familial ALS (fALS), SOD1 does not contribute to the toxicity of sALS astrocytes. Death of MNs triggered by either sALS or fALS astrocytes occurs through necroptosis, a form of programmed necrosis involving receptor-interacting protein 1 and the mixed lineage kinase domain-like protein. The necroptotic pathway therefore constitutes a potential therapeutic target for this incurable disease.
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Affiliation(s)
- Diane B Re
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Virginia Le Verche
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Changhao Yu
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Mackenzie W Amoroso
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA; Department of Rehabilitation and Regenerative Medicine, Columbia University, New York, NY 10032, USA; Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | - Kristin A Politi
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Sudarshan Phani
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Burcin Ikiz
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Lucas Hoffmann
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA
| | - Martijn Koolen
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Academisch Medisch Centrum, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Tetsuya Nagata
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Dimitra Papadimitriou
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Peter Nagy
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Hiroshi Mitsumoto
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Shingo Kariya
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Hynek Wichterle
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | - Christopher E Henderson
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Department of Rehabilitation and Regenerative Medicine, Columbia University, New York, NY 10032, USA; Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | - Serge Przedborski
- Center for Motor Neuron Biology and Disease, the Columbia Translational Neuroscience Initiative, and the Columbia Stem Cell Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA.
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271
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Akay T. Long-term measurement of muscle denervation and locomotor behavior in individual wild-type and ALS model mice. J Neurophysiol 2014; 111:694-703. [DOI: 10.1152/jn.00507.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The increasing number of mouse models of human degenerative and injury-related diseases that affect motor behavior raises the importance of in vivo methodologies allowing measurement of physiological and behavioral changes over an extended period of time in individual animals. A method that provides long-term measurements of muscle denervation and its behavioral consequences in individual mice for several months is presented in this article. The method is applied to mSod1G93A mice, which model human amyotrophic lateral sclerosis (ALS). The denervation process of gastrocnemius and soleus muscles in mSod1G93A mice is demonstrated for up to 3 mo. The data suggest that as muscle denervation progresses, massive behavioral compensation occurs within the spinal cord that allows animals to walk almost normally until late ages. Only around the age of 84 days is the first sign of abnormal movement during walking behavior detected as an abnormal tibialis anterior activity profile that is manifested in subtle but abnormal swing movement during walking. Additionally, this method can be used with other mouse models of human diseases, such as spinal cord injury, intracerebral hemorrhage, Parkinson's diseases, and spinal muscular atrophy.
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Affiliation(s)
- Turgay Akay
- Department of Neurological Surgery, Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, New York
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272
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ATF3 expression improves motor function in the ALS mouse model by promoting motor neuron survival and retaining muscle innervation. Proc Natl Acad Sci U S A 2014; 111:1622-7. [PMID: 24474789 DOI: 10.1073/pnas.1314826111] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ALS is a fatal neurodegenerative disease characterized by a progressive loss of motor neurons and atrophy of distal axon terminals in muscle, resulting in loss of motor function. Motor end plates denervated by axonal retraction of dying motor neurons are partially reinnervated by remaining viable motor neurons; however, this axonal sprouting is insufficient to compensate for motor neuron loss. Activating transcription factor 3 (ATF3) promotes neuronal survival and axonal growth. Here, we reveal that forced expression of ATF3 in motor neurons of transgenic SOD1(G93A) ALS mice delays neuromuscular junction denervation by inducing axonal sprouting and enhancing motor neuron viability. Maintenance of neuromuscular junction innervation during the course of the disease in ATF3/SOD1(G93A) mice is associated with a substantial delay in muscle atrophy and improved motor performance. Although disease onset and mortality are delayed, disease duration is not affected. This study shows that adaptive axonal growth-promoting mechanisms can substantially improve motor function in ALS and importantly, that augmenting viability of the motor neuron soma and maintaining functional neuromuscular junction connections are both essential elements in therapy for motor neuron disease in the SOD1(G93A) mice. Accordingly, effective protection of optimal motor neuron function requires restitution of multiple dysregulated cellular pathways.
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273
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Tamai SI, Imaizumi K, Kurabayashi N, Nguyen MD, Abe T, Inoue M, Fukada Y, Sanada K. Neuroprotective role of the basic leucine zipper transcription factor NFIL3 in models of amyotrophic lateral sclerosis. J Biol Chem 2013; 289:1629-38. [PMID: 24280221 DOI: 10.1074/jbc.m113.524389] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of motor neurons. Here we show that the basic leucine zipper transcription factor NFIL3 (also called E4BP4) confers neuroprotection in models of ALS. NFIL3 is up-regulated in primary neurons challenged with neurotoxic insults and in a mouse model of ALS. Overexpression of NFIL3 attenuates excitotoxic neuronal damage and protects neurons against neurodegeneration in a cell-based ALS model. Conversely, reduction of NFIL3 exacerbates neuronal demise in adverse conditions. Transgenic neuronal expression of NFIL3 in ALS mice delays disease onset and attenuates motor axon and neuron degeneration. These results suggest that NFIL3 plays a neuroprotective role in neurons and constitutes a potential therapeutic target for neurodegeneration.
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Affiliation(s)
- So-ichi Tamai
- From the Molecular Genetics Research Laboratory, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
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274
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Marklund U, Alekseenko Z, Andersson E, Falci S, Westgren M, Perlmann T, Graham A, Sundström E, Ericson J. Detailed expression analysis of regulatory genes in the early developing human neural tube. Stem Cells Dev 2013; 23:5-15. [PMID: 24007338 DOI: 10.1089/scd.2013.0309] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Studies in model organisms constitute the basis of our understanding of the principal molecular mechanisms of cell fate determination in the developing central nervous system. Considering the emergent applications in stem cell-based regenerative medicine, it is important to demonstrate conservation of subtype specific gene expression programs in human as compared to model vertebrates. We have examined the expression patterns of key regulatory genes in neural progenitor cells and their neuronal and glial descendants in the developing human spinal cord, hindbrain, and midbrain, and compared these with developing mouse and chicken embryos. As anticipated, gene expression patterns are highly conserved between these vertebrate species, but there are also features that appear unique to human development. In particular, we find that neither tyrosine hydroxylase nor Nurr1 are specific markers for mesencephalic dopamine neurons, as these genes also are expressed in other neuronal subtypes in the human ventral midbrain and in human embryonic stem cell cultures directed to differentiate towards a ventral mesencephalic identity. Moreover, somatic motor neurons in the ventral spinal cord appear to be produced by two molecularly distinct ventral progenitor populations in the human, raising the possibility that the acquisition of unique ventral progenitor identities may have contributed to the emergence of neural subtypes in higher vertebrates.
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Affiliation(s)
- Ulrika Marklund
- 1 Department of Cell and Molecular Biology, Karolinska Institutet , Stockholm, Sweden
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275
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Saxena S, Roselli F, Singh K, Leptien K, Julien JP, Gros-Louis F, Caroni P. Neuroprotection through Excitability and mTOR Required in ALS Motoneurons to Delay Disease and Extend Survival. Neuron 2013; 80:80-96. [DOI: 10.1016/j.neuron.2013.07.027] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2013] [Indexed: 12/13/2022]
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276
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Onodera O, Ishihara T, Shiga A, Ariizumi Y, Yokoseki A, Nishizawa M. Minor splicing pathway is not minor any more: implications for the pathogenesis of motor neuron diseases. Neuropathology 2013; 34:99-107. [PMID: 24112438 DOI: 10.1111/neup.12070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 08/21/2013] [Indexed: 12/13/2022]
Abstract
To explore the molecular pathogenesis of amyotrophic lateral sclerosis (ALS), the nuclear function of TAR-DNA binding protein 43 kDa (TDP-43) must be elucidated. TDP-43 is a nuclear protein that colocalizes with Cajal body or Gem in cultured cells. Several recent studies have reported that the decreasing number of Gems accompanied the depletion of the causative genes for ALS, TDP-43 and FUS. Gems play an important role in the pathogenesis of spinal muscular atrophy. Gems are the sites of the maturation of spliceosomes, which are composed of uridylate-rich (U) snRNAs (small nuclear RNAs) and protein complex, small nuclear ribonuclearprotein (snRNP). Spliceosomes regulate the splicing of pre-mRNA and are classified into the major or minor classes, according to the consensus sequence of acceptor and donor sites of pre-mRNA splicing. Although the major class of spliceosomes regulates most pre-mRNA splicing, minor spliceosomes also play an important role in regulating the splicing or global speed of pre-mRNA processing. A mouse model of spinal muscular atrophy, in which the number of Gems is decreased, shows fewer subsets U snRNAs. Interestingly, in the central nervous system, U snRNAs belonging to the minor spliceosomes are markedly reduced. In ALS, the U12 snRNA is decreased only in the tissue affected by ALS and not in other tissues. Although the molecular mechanisms underlying the decreased U12 snRNA resulting in cell dysfunction and cell death in motor neuron diseases remain unclear, these findings suggest that the disturbance of nuclear bodies and minor splicing may underlie the common molecular pathogenesis of motor neuron diseases.
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Affiliation(s)
- Osamu Onodera
- Department of Molecular Neuroscience, Brain Research Institute, Niigata University, Niigata, Japan
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277
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Death Receptors in the Selective Degeneration of Motoneurons in Amyotrophic Lateral Sclerosis. JOURNAL OF NEURODEGENERATIVE DISEASES 2013; 2013:746845. [PMID: 26316997 PMCID: PMC4437334 DOI: 10.1155/2013/746845] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/28/2013] [Indexed: 12/13/2022]
Abstract
While studies on death receptors have long been restricted to immune cells, the last decade has provided a strong body of evidence for their implication in neuronal death and hence neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS). ALS is a fatal paralytic disorder that primarily affects motoneurons in the brain and spinal cord. A neuroinflammatory process, associated with astrocyte and microglial activation as well as infiltration of immune cells, accompanies motoneuron degeneration and supports the contribution of non-cell-autonomous mechanisms in the disease. Hallmarks of Fas, TNFR, LT-βR, and p75NTR signaling have been observed in both animal models and ALS patients. This review summarizes to date knowledge of the role of death receptors in ALS and the link existing between the selective loss of motoneurons and neuroinflammation. It further suggests how this recent evidence could be included in an ultimate multiapproach to treat patients.
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278
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Opportunities and challenges of pluripotent stem cell neurodegenerative disease models. Nat Neurosci 2013; 16:780-9. [PMID: 23799470 DOI: 10.1038/nn.3425] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 05/05/2013] [Indexed: 02/06/2023]
Abstract
Human neurodegenerative disorders are among the most difficult to study. In particular, the inability to readily obtain the faulty cell types most relevant to these diseases has impeded progress for decades. Recent advances in pluripotent stem cell technology now grant access to substantial quantities of disease-pertinent neurons both with and without predisposing mutations. While this suite of technologies has revolutionized the field of 'in vitro disease modeling', great care must be taken in their deployment if robust, durable discoveries are to be made. Here we review what we perceive to be several of the stumbling blocks in the use of stem cells for the study of neurological disease and offer strategies to overcome them.
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279
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Embryonic alteration of motoneuronal morphology induces hyperexcitability in the mouse model of amyotrophic lateral sclerosis. Neurobiol Dis 2013; 54:116-26. [DOI: 10.1016/j.nbd.2013.02.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 01/31/2013] [Accepted: 02/22/2013] [Indexed: 12/12/2022] Open
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280
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Nichols NL, Van Dyke J, Nashold L, Satriotomo I, Suzuki M, Mitchell GS. Ventilatory control in ALS. Respir Physiol Neurobiol 2013; 189:429-37. [PMID: 23692930 DOI: 10.1016/j.resp.2013.05.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/13/2013] [Accepted: 05/13/2013] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to "fight back" via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients.
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Affiliation(s)
- Nicole L Nichols
- Department of Comparative Biosciences, University of Wisconsin, School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA
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281
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de Nooij JC, Doobar S, Jessell TM. Etv1 inactivation reveals proprioceptor subclasses that reflect the level of NT3 expression in muscle targets. Neuron 2013; 77:1055-68. [PMID: 23522042 DOI: 10.1016/j.neuron.2013.01.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2013] [Indexed: 01/12/2023]
Abstract
The organization of spinal reflex circuits relies on the specification of distinct classes of proprioceptive sensory neurons (pSN), but the factors that drive such diversity remain unclear. We report here that pSNs supplying distinct skeletal muscles differ in their dependence on the ETS transcription factor Etv1 for their survival and differentiation. The status of Etv1-dependence is linked to the location of proprioceptor muscle targets: pSNs innervating hypaxial and axial muscles depend critically on Etv1 for survival, whereas those innervating certain limb muscles are resistant to Etv1 inactivation. The level of NT3 expression in individual muscles correlates with Etv1-dependence and the loss of pSNs triggered by Etv1 inactivation can be prevented by elevating the level of muscle-derived NT3-revealing a TrkC-activated Etv1-bypass pathway. Our findings support a model in which the specification of aspects of pSN subtype character is controlled by variation in the level of muscle NT3 expression and signaling.
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Affiliation(s)
- Joriene C de Nooij
- Department of Neuroscience, Howard Hughes Medical Institute, Kavli Institute for Brain Science, Columbia University, New York, NY 10032, USA
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282
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Yasvoina MV, Genç B, Jara JH, Sheets PL, Quinlan KA, Milosevic A, Shepherd GM, Heckman CJ, Özdinler PH. eGFP expression under UCHL1 promoter genetically labels corticospinal motor neurons and a subpopulation of degeneration-resistant spinal motor neurons in an ALS mouse model. J Neurosci 2013; 33:7890-904. [PMID: 23637180 PMCID: PMC3963467 DOI: 10.1523/jneurosci.2787-12.2013] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 03/12/2013] [Accepted: 03/26/2013] [Indexed: 12/29/2022] Open
Abstract
Understanding mechanisms that lead to selective motor neuron degeneration requires visualization and cellular identification of vulnerable neurons. Here we report generation and characterization of UCHL1-eGFP and hSOD1(G93A)-UeGFP mice, novel reporter lines for cortical and spinal motor neurons. Corticospinal motor neurons (CSMN) and a subset of spinal motor neurons (SMN) are genetically labeled in UCHL1-eGFP mice, which express eGFP under the UCHL1 promoter. eGFP expression is stable and continues through P800 in vivo. Retrograde labeling, molecular marker expression, electrophysiological analysis, and cortical circuit mapping confirmed CSMN identity of eGFP(+) neurons in the motor cortex. Anatomy, molecular marker expression, and electrophysiological analysis revealed that the eGFP expression is restricted to a subset of small-size SMN that are slow-twitch α and γ motor neurons. Crossbreeding of UCHL1-eGFP and hSOD1(G93A) lines generated hSOD1(G93A)-UeGFP mice, which displayed the disease phenotype observed in a hSOD1(G93A) mouse model of ALS. eGFP(+) SMN showed resistance to degeneration in hSOD1(G93A)-UeGFP mice, and their slow-twitch α and γ motor neuron identity was confirmed. In contrast, eGFP(+) neurons in the motor cortex of hSOD1(G93A)-UeGFP mice recapitulated previously reported progressive CSMN loss and apical dendrite degeneration. Our findings using these two novel reporter lines revealed accumulation of autophagosomes along the apical dendrites of vulnerable CSMN at P60, early symptomatic stage, suggesting autophagy as a potential intrinsic mechanism for CSMN apical dendrite degeneration.
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Affiliation(s)
| | - Barış Genç
- Davee Department of Neurology and Clinical Neurological Sciences
| | - Javier H. Jara
- Davee Department of Neurology and Clinical Neurological Sciences
| | | | | | - Ana Milosevic
- Laboratory for Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10065, and
| | | | - C. J. Heckman
- Department of Physiology, and
- Physical Medicine and Rehabilitation Institute, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611
- Physical Therapy and Human Movement Sciences Center
| | - P. Hande Özdinler
- Davee Department of Neurology and Clinical Neurological Sciences
- Robert H. Lurie Comprehensive Cancer Center, and
- Cognitive Neurology and Alzheimer's Disease Center, Northwestern University, Chicago, Illinois 60611
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283
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Baek M, Enriquez J, Mann RS. Dual role for Hox genes and Hox co-factors in conferring leg motoneuron survival and identity in Drosophila. Development 2013; 140:2027-38. [PMID: 23536569 DOI: 10.1242/dev.090902] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Adult Drosophila walk using six multi-jointed legs, each controlled by ∼50 leg motoneurons (MNs). Although MNs have stereotyped morphologies, little is known about how they are specified. Here, we describe the function of Hox genes and homothorax (hth), which encodes a Hox co-factor, in Drosophila leg MN development. Removing either Hox or Hth function from a single neuroblast (NB) lineage results in MN apoptosis. A single Hox gene, Antennapedia (Antp), is primarily responsible for MN survival in all three thoracic segments. When cell death is blocked, partially penetrant axon branching errors are observed in Hox mutant MNs. When single MNs are mutant, errors in both dendritic and axon arborizations are observed. Our data also suggest that Antp levels in post-mitotic MNs are important for specifying their identities. Thus, in addition to being essential for survival, Hox and hth are required to specify accurate MN morphologies in a level-dependent manner.
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Affiliation(s)
- Myungin Baek
- Department of Biological Sciences, Columbia University, 701 W. 168th Street, New York, NY 10032, USA
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284
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Wootz H, Fitzsimons-Kantamneni E, Larhammar M, Rotterman TM, Enjin A, Patra K, André E, Van Zundert B, Kullander K, Alvarez FJ. Alterations in the motor neuron-renshaw cell circuit in the Sod1(G93A) mouse model. J Comp Neurol 2013; 521:1449-69. [PMID: 23172249 DOI: 10.1002/cne.23266] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 09/14/2012] [Accepted: 11/06/2012] [Indexed: 12/12/2022]
Abstract
Motor neurons become hyperexcitable during progression of amyotrophic lateral sclerosis (ALS). This abnormal firing behavior has been explained by changes in their membrane properties, but more recently it has been suggested that changes in premotor circuits may also contribute to this abnormal activity. The specific circuits that may be altered during development of ALS have not been investigated. Here we examined the Renshaw cell recurrent circuit that exerts inhibitory feedback control on motor neuron firing. Using two markers for Renshaw cells (calbindin and cholinergic nicotinic receptor subunit alpha2 [Chrna2]), two general markers for motor neurons (NeuN and vesicular acethylcholine transporter [VAChT]), and two markers for fast motor neurons (Chondrolectin and calcitonin-related polypeptide alpha [Calca]), we analyzed the survival and connectivity of these cells during disease progression in the Sod1(G93A) mouse model. Most calbindin-immunoreactive (IR) Renshaw cells survive to end stage but downregulate postsynaptic Chrna2 in presymptomatic animals. In motor neurons, some markers are downregulated early (NeuN, VAChT, Chondrolectin) and others at end stage (Calca). Early downregulation of presynaptic VAChT and Chrna2 was correlated with disconnection from Renshaw cells as well as major structural abnormalities of motor axon synapses inside the spinal cord. Renshaw cell synapses on motor neurons underwent more complex changes, including transitional sprouting preferentially over remaining NeuN-IR motor neurons. We conclude that the loss of presynaptic motor axon input on Renshaw cells occurs at early stages of ALS and disconnects the recurrent inhibitory circuit, presumably resulting in diminished control of motor neuron firing. J. Comp. Neurol. 521:1449-1469, 2013. © 2012 Wiley Periodicals, Inc.
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Affiliation(s)
- Hanna Wootz
- Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
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285
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Ruiz R, Tabares L. Neurotransmitter release in motor nerve terminals of a mouse model of mild spinal muscular atrophy. J Anat 2013; 224:74-84. [PMID: 23489475 DOI: 10.1111/joa.12038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2013] [Indexed: 12/14/2022] Open
Abstract
Spinal muscular atrophy is a genetic disease which severity depends on the amount of SMN protein, the product of the genes SMN1 and SMN2. Symptomatology goes from severe neuromuscular impairment leading to early death in infants to slow progressing motor deficits during adulthood. Much of the knowledge about the pathophysiology of SMA comes from studies using genetically engineered animal models of the disease. Here we investigated one of the milder models, the homozygous A2G SMA mice, in which the level of the protein is restored to almost normal levels by the addition of a mutated transgene to the severe SMN-deficient background. We examined neuromuscular function and found that calcium-dependent neurotransmitter release was significantly decreased. In addition, the amplitude of spontaneous endplate potentials was decreased, the morphology of NMJ altered, and slight changes in short-term synaptic plasticity were found. In spite of these defects, excitation contraction coupling was well preserved, possibly due to the safety factor of this synapse. These data further support that the quasi-normal restoration of SMN levels in severe cases preserves neuromuscular function, even when neurotransmitter release is significantly decreased at motor nerve terminals. Nevertheless, this deficit could represent a greater risk of motor impairment during aging or after injuries.
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Affiliation(s)
- Rocío Ruiz
- Department of Medical Physiology and Biophysics School of Medicine, University of Seville, Seville, Spain
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286
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Robberecht W, Philips T. The changing scene of amyotrophic lateral sclerosis. Nat Rev Neurosci 2013; 14:248-64. [PMID: 23463272 DOI: 10.1038/nrn3430] [Citation(s) in RCA: 745] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Several recent breakthroughs have provided notable insights into the pathogenesis of amyotrophic lateral sclerosis (ALS), with some even shifting our thinking about this neurodegenerative disease and raising the question as to whether this disorder is a proteinopathy, a ribonucleopathy or both. In addition, these breakthroughs have revealed mechanistic links between ALS and frontotemporal dementia, as well as between ALS and other neurodegenerative diseases, such as the cerebellar atrophies, myotonic dystrophy and inclusion body myositis. Here, we summarize the new findings in ALS research, discuss what they have taught us about this disease and examine issues that are still outstanding.
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Affiliation(s)
- Wim Robberecht
- Laboratory of Neurobiology, VIB Vesalius Research Center, 3000 Leuven, Belgium.
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287
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Abstract
Human pluripotent stem cells are a promising source of differentiated cells for developmental studies, cell transplantation, disease modeling, and drug testing. However, their widespread use even for intensely studied cell types like spinal motor neurons is hindered by the long duration and low yields of existing protocols for in vitro differentiation and by the molecular heterogeneity of the populations generated. We report a combination of small molecules that within 3 weeks induce motor neurons at up to 50% abundance and with defined subtype identities of relevance to neurodegenerative disease. Despite their accelerated differentiation, motor neurons expressed combinations of HB9, ISL1, and column-specific markers that mirror those observed in vivo in human embryonic spinal cord. They also exhibited spontaneous and induced activity, and projected axons toward muscles when grafted into developing chick spinal cord. Strikingly, this novel protocol preferentially generates motor neurons expressing markers of limb-innervating lateral motor column motor neurons (FOXP1(+)/LHX3(-)). Access to high-yield cultures of human limb-innervating motor neuron subtypes will facilitate in-depth study of motor neuron subtype-specific properties, disease modeling, and development of large-scale cell-based screening assays.
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288
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Piccinini E, Kalkkinen N, Saarma M, Runeberg-Roos P. Glial cell line-derived neurotrophic factor: characterization of mammalian posttranslational modifications. Ann Med 2013; 45:66-73. [PMID: 23305235 DOI: 10.3109/07853890.2012.663927] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Although glial cell line-derived neurotrophic factor (GDNF) has a strong clinical potential, little is known of how the posttranslational modifications of GDNF affect its biological activity and therapeutic potential. In mammalian cells GDNF is synthesized as a preproprotein. During secretion GDNF dimerizes, folds with -S-S- bonds, is modified by N-linked glycosylation, and undergoes proteolytic processing. After production in E. coli, unglycosylated GDNF is renaturated in vitro. Nevertheless, GDNF from E. coli was used in Parkinson's disease-related clinical trials. MATERIAL AND METHODS Constructs encoding variants of human GDNF were generated and expressed in mammalian cells. The proteins were analysed by SDS-PAGE, Western blotting, RET-phosphorylation assays, and N-terminal sequencing. The stability of mammalian GDNF was compared to commercial GDNF produced in E. coli. RESULTS Posttranslational processing of mammalian GDNF depends on the expression conditions. Two forms of GDNF with different N-termini are formed. GDNF without a prosequence is secreted and biologically active. GDNF is modified by N-linked glycosylation at one (Asn(49)) out of two consensus sites. N-linked glycosylation aids proteolytic processing of GDNF. Both glycosylated and unglycosylated GDNF from mammalian cells are more stable than GDNF from E. coli. DISCUSSION Posttranslational modifications of GDNF influence its stability, which may be critical for its clinical use.
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Affiliation(s)
- Elisa Piccinini
- Institute of Biotechnology, University of Helsinki, PB 56 Viikinkaari 9, SF-00014, University of Helsinki, Finland
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289
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Kim JY, Ash RT, Ceballos-Diaz C, Levites Y, Golde TE, Smirnakis SM, Jankowsky JL. Viral transduction of the neonatal brain delivers controllable genetic mosaicism for visualising and manipulating neuronal circuits in vivo. Eur J Neurosci 2013; 37:1203-20. [PMID: 23347239 DOI: 10.1111/ejn.12126] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/09/2012] [Accepted: 12/12/2012] [Indexed: 12/19/2022]
Abstract
The neonatal intraventricular injection of adeno-associated virus has been shown to transduce neurons widely throughout the brain, but its full potential for experimental neuroscience has not been adequately explored. We report a detailed analysis of the method's versatility with an emphasis on experimental applications where tools for genetic manipulation are currently lacking. Viral injection into the neonatal mouse brain is fast, easy, and accesses regions of the brain including the cerebellum and brainstem that have been difficult to target with other techniques such as electroporation. We show that viral transduction produces an inherently mosaic expression pattern that can be exploited by varying the titer to transduce isolated neurons or densely-packed populations. We demonstrate that the expression of virally-encoded proteins is active much sooner than previously believed, allowing genetic perturbation during critical periods of neuronal plasticity, but is also long-lasting and stable, allowing chronic studies of aging. We harness these features to visualise and manipulate neurons in the hindbrain that have been recalcitrant to approaches commonly applied in the cortex. We show that viral labeling aids the analysis of postnatal dendritic maturation in cerebellar Purkinje neurons by allowing individual cells to be readily distinguished, and then demonstrate that the same sparse labeling allows live in vivo imaging of mature Purkinje neurons at a resolution sufficient for complete analytical reconstruction. Given the rising availability of viral constructs, packaging services, and genetically modified animals, these techniques should facilitate a wide range of experiments into brain development, function, and degeneration.
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Affiliation(s)
- Ji-Yoen Kim
- Department of Neuroscience, Baylor College of Medicine, BCM295, One Baylor Plaza, Houston, TX 77030, USA
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290
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McKinnon DD, Kloxin AM, Anseth KS. Synthetic hydrogel platform for three-dimensional culture of embryonic stem cell-derived motor neurons. Biomater Sci 2013; 1:460-469. [DOI: 10.1039/c3bm00166k] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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291
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Nichols NL, Gowing G, Satriotomo I, Nashold LJ, Dale EA, Suzuki M, Avalos P, Mulcrone PL, McHugh J, Svendsen CN, Mitchell GS. Intermittent hypoxia and stem cell implants preserve breathing capacity in a rodent model of amyotrophic lateral sclerosis. Am J Respir Crit Care Med 2012; 187:535-42. [PMID: 23220913 DOI: 10.1164/rccm.201206-1072oc] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
RATIONALE Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease causing paralysis and death from respiratory failure. Strategies to preserve and/or restore respiratory function are critical for successful treatment. Although breathing capacity is maintained until late in disease progression in rodent models of familial ALS (SOD1(G93A) rats and mice), reduced numbers of phrenic motor neurons and decreased phrenic nerve activity are observed. Decreased phrenic motor output suggests imminent respiratory failure. OBJECTIVES To preserve or restore phrenic nerve activity in SOD1(G93A) rats at disease end stage. METHODS SOD1(G93A) rats were injected with human neural progenitor cells (hNPCs) bracketing the phrenic motor nucleus before disease onset, or exposed to acute intermittent hypoxia (AIH) at disease end stage. MEASUREMENTS AND MAIN RESULTS The capacity to generate phrenic motor output in anesthetized rats at disease end stage was: (1) transiently restored by a single presentation of AIH; and (2) preserved ipsilateral to hNPC transplants made before disease onset. hNPC transplants improved ipsilateral phrenic motor neuron survival. CONCLUSIONS AIH-induced respiratory plasticity and stem cell therapy have complementary translational potential to treat breathing deficits in patients with ALS.
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Affiliation(s)
- Nicole L Nichols
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, USA
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292
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Gender-specific perturbations in modulatory inputs to motoneurons in a mouse model of amyotrophic lateral sclerosis. Neuroscience 2012; 226:313-23. [DOI: 10.1016/j.neuroscience.2012.09.031] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/10/2012] [Accepted: 09/11/2012] [Indexed: 12/12/2022]
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293
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Liu C, Ma W, Su W, Zhang J. Prdm14 acts upstream of islet2 transcription to regulate axon growth of primary motoneurons in zebrafish. Development 2012; 139:4591-600. [PMID: 23136389 DOI: 10.1242/dev.083055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The precise formation of three-dimensional motor circuits is essential for movement control. Within these circuits, motoneurons (MNs) are specified from spinal progenitors by dorsoventral signals and distinct transcriptional programs. Different MN subpopulations have stereotypic cell body positions and show specific spatial axon trajectories. Our knowledge of MN axon outgrowth remains incomplete. Here, we report a zebrafish gene-trap mutant, short lightning (slg), in which prdm14 expression is disrupted. slg mutant embryos show shortened axons in caudal primary (CaP) MNs resulting in defective embryonic movement. Both the CaP neuronal defects and behavior abnormality of the mutants can be phenocopied by injection of a prdm14 morpholino into wild-type embryos. By removing a copy of the inserted transposon from homozygous mutants, prdm14 expression and normal embryonic movement were restored, confirming that loss of prdm14 expression accounts for the observed defects. Mechanistically, Prdm14 protein binds to the promoter region of islet2, a known transcription factor required for CaP development. Notably, disruption of islet2 function caused similar CaP axon outgrowth defects as observed in slg mutant embryos. Furthermore, overexpression of islet2 in slg mutant embryos rescued the shortened CaP axon phenotypes. Together, these data reveal that prdm14 regulates CaP axon outgrowth through activation of islet2 expression.
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Affiliation(s)
- Chao Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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294
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Zetterström P, Graffmo KS, Andersen PM, Brännström T, Marklund SL. Composition of soluble misfolded superoxide dismutase-1 in murine models of amyotrophic lateral sclerosis. Neuromolecular Med 2012; 15:147-58. [PMID: 23076707 DOI: 10.1007/s12017-012-8204-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 10/05/2012] [Indexed: 12/13/2022]
Abstract
A common cause of amyotrophic lateral sclerosis is mutations in superoxide dismutase-1, which provoke the disease by an unknown mechanism. We have previously found that soluble hydrophobic misfolded mutant human superoxide dismutase-1 species are enriched in the vulnerable spinal cords of transgenic model mice. The levels were broadly inversely correlated with life spans, suggesting involvement in the pathogenesis. Here, we used methods based on antihuman superoxide dismutase-1 peptide antibodies specific for misfolded species to explore the composition and amounts of soluble misfolded human superoxide dismutase-1 in tissue extracts. Mice expressing 5 different human superoxide dismutase-1 variants with widely variable structural characteristics were examined. The levels were generally higher in spinal cords than in other tissues. The major portion of misfolded superoxide dismutase-1 was shown to be monomers lacking the C57-C146 disulfide bond with large hydrodynamic volume, indicating a severely disordered structure. The remainder of the misfolded protein appeared to be non-covalently associated in 130- and 250-kDa complexes. The malleable monomers should be prone to aggregate and associate with other cellular components, and should be easily translocated between compartments. They may be the primary cause of toxicity in superoxide dismutase-1-induced amyotrophic lateral sclerosis.
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Affiliation(s)
- Per Zetterström
- Department of Medical Biosciences, Clinical Chemistry, Umeå University, 901 85, Umeå, Sweden
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295
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Grumbles RM, Almeida VW, Casella GTB, Wood PM, Hemstapat K, Thomas CK. Motoneuron replacement for reinnervation of skeletal muscle in adult rats. J Neuropathol Exp Neurol 2012; 71:921-30. [PMID: 22964786 PMCID: PMC3760019 DOI: 10.1097/nen.0b013e31826cf69a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Reinnervation is needed to rescue muscle when motoneurons die in disease or injury. Embryonic ventral spinal cord cells transplanted into peripheral nerve reinnervate muscle and reduce atrophy, but low motoneuron survival may limit motor unit formation. We tested whether transplantation of a purified population of embryonic motoneurons into peripheral nerve (mean ± SE, 146,458 ± 4,011 motoneurons) resulted in more motor units and reinnervation than transplantation of a mixed population of ventral spinal cord cells (72,075 ± 12,329 motoneurons). Ten weeks after either kind of transplant, similar numbers of neurons expressed choline acetyl transferase and/or Islet-1. Motoneuron numbers always exceeded the reinnervated motor unit count. Most motor end plate were simple plaques. Reinnervation significantly reduced muscle fiber atrophy. These data show that the number of transplanted motoneurons and motoneuron survival do not limit muscle reinnervation. Incomplete differentiation of motoneurons in nerve and lack of muscle activity may result in immature neuromuscular junctions that limit reinnervation and function.
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Affiliation(s)
- Robert M Grumbles
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida 33136-2104, USA
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296
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Katsumata R, Ishigaki S, Katsuno M, Kawai K, Sone J, Huang Z, Adachi H, Tanaka F, Urano F, Sobue G. c-Abl inhibition delays motor neuron degeneration in the G93A mouse, an animal model of amyotrophic lateral sclerosis. PLoS One 2012; 7:e46185. [PMID: 23049975 PMCID: PMC3458026 DOI: 10.1371/journal.pone.0046185] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 08/28/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive death of motor neurons. Although the pathogenesis of ALS remains unclear, several cellular processes are known to be involved, including apoptosis. A previous study revealed the apoptosis-related gene c-Abl to be upregulated in sporadic ALS motor neurons. METHODOLOGY/FINDINGS We investigated the possibility that c-Abl activation is involved in the progression of ALS and that c-Abl inhibition is potentially a therapeutic strategy for ALS. Using a mouse motor neuron cell line, we found that mutation of Cu/Zn-superoxide dismutase-1 (SOD1), which is one of the causative genes of familial ALS, induced the upregulation of c-Abl and decreased cell viability, and that the c-Abl inhibitor dasatinib inhibited cytotoxicity. Activation of c-Abl with a concomitant increase in activated caspase-3 was observed in the lumbar spine of G93A-SOD1 transgenic mice (G93A mice), a widely used model of ALS. The survival of G93A mice was improved by oral administration of dasatinib, which also decreased c-Abl phosphorylation, inactivated caspase-3, and improved the innervation status of neuromuscular junctions. In addition, c-Abl expression in postmortem spinal cord tissues from sporadic ALS patients was increased by 3-fold compared with non-ALS patients. CONCLUSIONS/SIGNIFICANCE The present results suggest that c-Abl is a potential therapeutic target for ALS and that the c-Abl inhibitor dasatinib has neuroprotective properties in vitro and in vivo.
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Affiliation(s)
- Ryu Katsumata
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Shinsuke Ishigaki
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Kaori Kawai
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Jun Sone
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Zhe Huang
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Hiroaki Adachi
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Fumiaki Tanaka
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
| | - Fumihiko Urano
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan
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297
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Rodriguez M, Choi J, Park S, Sockanathan S. Gde2 regulates cortical neuronal identity by controlling the timing of cortical progenitor differentiation. Development 2012; 139:3870-9. [PMID: 22951639 DOI: 10.1242/dev.081083] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mammalian cortex is a multilaminar structure consisting of specialized layer-specific neurons that form complex circuits throughout the brain and spinal cord. These neurons are generated in a defined sequence dictated by their birthdate such that early-born neurons settle in deep cortical layers whereas late-born neurons populate more superficial layers. Cortical neuronal birthdate is partly controlled by an intrinsic clock-type mechanism; however, the role of extrinsic factors in the temporal control of cell-cycle exit is less clear. Here, we show that Gde2, a six-transmembrane protein that induces spinal neuronal differentiation, is expressed in the developing cortex throughout cortical neurogenesis. In the absence of Gde2, cortical progenitors fail to exit the cell cycle on time, remain cycling, accumulate and exit the cell cycle en masse towards the end of the neurogenic period. These dynamic changes in cell-cycle progression cause deficits and delays in deep-layer neuronal differentiation and robust increases in superficial neuronal numbers. Gde2(-/-) cortices show elevated levels of Notch signaling coincident with when progenitors fail to differentiate, suggesting that abnormal Notch activation retains cells in a proliferative phase that biases them to superficial fates. However, no change in Notch signaling is observed at the time of increased cell-cycle exit. These observations define a key role for Gde2 in controlling cortical neuronal fates by regulating the timing of neurogenesis, and show that loss of Gde2 uncovers additional mechanisms that trigger remaining neuronal progenitors to differentiate at the end of the neurogenic period.
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Affiliation(s)
- Marianeli Rodriguez
- The Solomon Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, PCTB1004, 725 N Wolfe Street, Baltimore, MD 21205, USA
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298
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Wnt7A identifies embryonic γ-motor neurons and reveals early postnatal dependence of γ-motor neurons on a muscle spindle-derived signal. J Neurosci 2012; 32:8725-31. [PMID: 22723712 DOI: 10.1523/jneurosci.1160-12.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Motor pools comprise a heterogeneous population of motor neurons that innervate distinct intramuscular targets. While the organization of motor neurons into motor pools has been well described, the time course and mechanism of motor pool diversification into functionally distinct classes remains unclear. γ-Motor neurons (γ-MNs) and α-motor neurons (α-MNs) differ in size, molecular identity, synaptic input and peripheral target. While α-MNs innervate extrafusal skeletal muscle fibers to mediate muscle contraction, γ-MNs innervate intrafusal fibers of the muscle spindle, and regulate sensitivity of the muscle spindle in response to stretch. In this study, we find that the secreted signaling molecule Wnt7a is selectively expressed in γ-MNs in the mouse spinal cord by embryonic day 17.5 and continues to molecularly distinguish γ-from α-MNs into the third postnatal week. Our data demonstrate that Wnt7a is the earliest known γ-MN marker, supporting a model of developmental divergence between α- and γ-MNs at embryonic stages. Furthermore, using Wnt7a expression as an early marker of γ-MN identity, we demonstrate a previously unknown dependence of γ-MNs on a muscle spindle-derived, GDNF-independent signal during the first postnatal week.
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Neuromuscular junction protection for the potential treatment of amyotrophic lateral sclerosis. Neurol Res Int 2012; 2012:379657. [PMID: 22919482 PMCID: PMC3423938 DOI: 10.1155/2012/379657] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 06/15/2012] [Accepted: 06/15/2012] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease characterized by the progressive degeneration of upper and lower motor neurons (MNs), leading to muscular atrophy and eventual respiratory failure. ALS research has primarily focused on mechanisms regarding MN cell death; however, degenerative processes in the skeletal muscle, particularly involving neuromuscular junctions (NMJs), are observed in the early stages of and throughout disease progression. According to the "dying-back" hypothesis, NMJ degeneration may not only precede, but actively cause upper and lower MN loss. The importance of NMJ pathology has relatively received little attention in ALS, possibly because compensatory mechanisms mask NMJ loss for prolonged periods. Many mechanisms explaining NMJ degeneration have been proposed such as the disruption of anterograde/retrograde axonal transport, irregular cellular metabolism, and changes in muscle gene and protein expression. Neurotrophic factors, which are known to have neuroprotective and regenerative properties, have been intensely investigated for their therapeutic potential in both the preclinical and clinical setting. Additional research should focus on the potential of preserving NMJs in order to delay or prevent disease progression.
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Misawa H, Hara M, Tanabe S, Niikura M, Moriwaki Y, Okuda T. Osteopontin is an alpha motor neuron marker in the mouse spinal cord. J Neurosci Res 2012; 90:732-42. [PMID: 22420030 DOI: 10.1002/jnr.22813] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Motor neurons (MNs) are designated as alpha/gamma and fast/slow based on their target sites and the types of muscle fibers innervated; however, few molecular markers that distinguish between these subtypes are available. Here we report that osteopontin (OPN) is a selective marker of alpha MNs in the mouse spinal cord. OPN was detected in approximately 70% of postnatal choline acetyltransferase (ChAT)-positive MNs with relatively large somas, but not in those with smaller somas. OPN+/ChAT+ MNs were also positive for NeuN, an alpha MN marker, but were negative for Err3, a gamma MN marker. The size distribution of OPN+/ChAT+ cells was nearly identical to that of NeuN+/ChAT+ alpha MNs. Group Ia proprioceptive terminals immunoreactive for vesicular glutamate transporter-1 were selectively detected on the OPN+/ChAT+ cells. OPN staining was also detected at motor axon terminals at neuromuscular junctions, where the OPN+ terminals were positive or negative for SV2A, a marker distinguishing fast/slow motor endplates. Finally, retrograde labeling following intramuscular injection of fast blue indicated that OPN is expressed in both fast and slow MNs. Collectively, our findings show that OPN is an alpha MN marker present in both the soma and the endplates of alpha MNs in the postnatal mouse spinal cord.
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Affiliation(s)
- Hidemi Misawa
- Department of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan.
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