scholarly journals Slit/Robo signals prevent spinal motor neuron emigration by organizing the spinal cord basement membrane

2019 ◽  
Author(s):  
Minkyung Kim ◽  
Clare H Lee ◽  
Sarah J Barnum ◽  
Roland CJ Watson ◽  
Jennifer Li ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Basement Membrane ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Neural Tube ◽  
Spinal Motor Neuron ◽  
Spinal Motor Neurons ◽  
Spinal Motor ◽  
Ventral Neural Tube ◽  
Set Up

AbstractThe developing spinal cord builds a boundary between the CNS and the periphery, in the form of a basement membrane. The spinal cord basement membrane is a barrier that retains CNS neuron cell bodies, while being selectively permeable to specific axon types. Spinal motor neuron cell bodies are located in the ventral neural tube next to the floor plate and project their axons out through the basement membrane to peripheral targets. However, little is known about how spinal motor neuron cell bodies are retained inside the ventral neural tube, while their axons can exit. In previous work, we found that disruption of Slit/Robo signals caused motor neuron emigration outside the spinal cord. In the current study, we investigate how Slit/Robo signals are necessary to keep spinal motor neurons within the neural tube. Our findings show that when Slit/Robo signals were removed from motor neurons, they migrated outside the spinal cord. Furthermore, this emigration was associated with abnormal basement membrane protein expression in the ventral spinal cord. Using Robo2 and Slit2 conditional mutants, we found that motor neuron-derived Slit/Robo signals were required to set up a normal basement membrane in the spinal cord. Together, our results suggest that motor neurons produce Slit signals that are required for the basement membrane assembly to retain motor neuron cell bodies within the spinal cord.

The zebrafish detour gene is essential for cranial but not spinal motor neuron induction

Development ◽  
1999 ◽  
Vol 126 (12) ◽  
pp. 2727-2737 ◽  
Author(s):  
A. Chandrasekhar ◽  
H.E. Schauerte ◽  
P. Haffter ◽  
J.Y. Kuwada
Keyword(s):  
Spinal Cord ◽  
Cell Death ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Spinal Motor Neuron ◽  
Neuronal Phenotype ◽  
Spinal Motor Neurons ◽  
Spinal Motor ◽  
Hh Signaling ◽  
Function Cell

The zebrafish detour (dtr) mutation generates a novel neuronal phenotype. In dtr mutants, most cranial motor neurons, especially the branchiomotor, are missing. However, spinal motor neurons are generated normally. The loss of cranial motor neurons is not due to aberrant hindbrain patterning, failure of neurogenesis, increased cell death or absence of hh expression. Furthermore, activation of the Hh pathway, which normally induces branchiomotor neurons, fails to induce motor neurons in the dtr hindbrain. Despite this, not all Hh-mediated regulation of hindbrain development is abolished since the regulation of a neural gene by Hh is intact in the dtr hindbrain. Finally, dtr can function cell autonomously to induce branchiomotor neurons. These results suggest that detour encodes a component of the Hh signaling pathway that is essential for the induction of motor neurons in the hindbrain but not in the spinal cord and that dtr function is required for the induction of only a subset of Hh-mediated events in the hindbrain.

scholarly journals Slit/Robo signals prevent spinal motor neuron emigration by organizing the spinal cord basement membrane.

2019 ◽  
Vol 455 (2) ◽  
pp. 449-457
Author(s):  
Minkyung Kim ◽  
Clare H. Lee ◽  
Sarah J. Barnum ◽  
Roland CJ. Watson ◽  
Jennifer Li ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Basement Membrane ◽  
Motor Neuron ◽  
Spinal Motor Neuron ◽  
Spinal Motor

scholarly journals Single-cell transcriptomic analysis of the adult mouse spinal cord

2020 ◽  
Author(s):  
Jacob A. Blum ◽  
Sandy Klemm ◽  
Lisa Nakayama ◽  
Arwa Kathiria ◽  
Kevin A. Guttenplan ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Single Cell ◽  
Motor Neurons ◽  
The Body ◽  
Molecular Heterogeneity ◽  
Spinal Motor Neuron ◽  
Spinal Motor ◽  
Full Complement ◽  
Adult Spinal Cord

AbstractThe spinal cord is a fascinating structure responsible for coordinating all movement in vertebrates. Spinal motor neurons control the activity of virtually every organ and muscle throughout the body by transmitting signals that originate in the spinal cord. These neurons are remarkably heterogeneous in their activity and innervation targets. However, because motor neurons represent only a small fraction of cells within the spinal cord and are difficult to isolate, the full complement of motor neuron subtypes remains unknown. Here we comprehensively describe the molecular heterogeneity of motor neurons within the adult spinal cord. We profiled 43,890 single-nucleus transcriptomes using fluorescence-activated nuclei sorting to enrich for spinal motor neuron nuclei. These data reveal a transcriptional map of the adult mammalian spinal cord and the first unbiased characterization of all transcriptionally distinct autonomic and somatic spinal motor neuron subpopulations. We identify 16 sympathetic motor neuron subtypes that segregate spatially along the spinal cord. Many of these subtypes selectively express specific hormones and receptors, suggesting neuromodulatory signaling within the autonomic nervous system. We describe skeletal motor neuron heterogeneity in the adult spinal cord, revealing numerous novel markers that distinguish alpha and gamma motor neurons—cell populations that are specifically affected in neurodegenerative disease. We also provide evidence for a novel transcriptional subpopulation of skeletal motor neurons. Collectively, these data provide a single-cell transcriptional atlas for investigating motor neuron diversity as well as the cellular and molecular basis of motor neuron function in health and disease.

Developmental regulation of the orphan receptor COUP-TF II gene in spinal motor neurons

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 25-36 ◽  
Author(s):  
B. Lutz ◽  
S. Kuratani ◽  
A.J. Cooney ◽  
S. Wawersik ◽  
S.Y. Tsai ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Thyroid Hormone ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Hormone Receptor ◽  
Thyroid Hormone Receptor ◽  
Orphan Receptor ◽  
Northern Analysis ◽  
Spinal Motor Neurons ◽  
Spinal Motor

Members of the steroid/thyroid hormone receptor superfamily are involved in the control of cell identity and of pattern formation during embryonic development. Chicken ovalbumin upstream promoter-transcription factors (COUP-TFs) can act as regulators of various steroid/thyroid hormone receptor pathways. To begin to study the role of COUP-TFs during embryogenesis, we cloned a chicken COUP-TF (cCOUP-TF II) which is highly homologous to human COUP-TF II. Northern analysis revealed high levels of cCOUP-TF II transcripts during organogenesis. Nuclear extracts from whole embryos and from embryonic spinal cords were used in electrophoretic mobility shift assays. These assays showed that COUP-TF protein is present in these tissues and is capable of binding to a COUP element (a direct repeat of AGGTCA with one base pair spacing). Analysis of cCOUP-TF expression by in situ hybridization revealed high levels of cCOUP-TF II mRNA in the developing spinal motor neurons. Since the ventral properties of the spinal cord, including the development of motor neurons, is in part established by inductive signals from the notochord, we transplanted an additional notochord next to the dorsal region of the neural tube in order to induce ectopic motor neurons. We observed that an ectopic notochord induced cCOUP-TF II gene expression in the dorsal spinal cord in a region coextensive with ectopic domains of SC1 and Islet-1, two previously identified motor neuron markers. Collectively, our studies raise the possibility that cCOUP-TF II is involved in motor neuron development.

scholarly journals The pathogenic role of c-Kit+ mast cells in the spinal motor neuron-vascular niche in ALS

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Mariángeles Kovacs ◽  
Catalina Alamón ◽  
Cecilia Maciel ◽  
Valentina Varela ◽  
Sofía Ibarburu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Mast Cells ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Immune Cells ◽  
Spinal Cord Tissue ◽  
Cell Reactivity ◽  
Spinal Motor Neuron ◽  
Spinal Motor ◽  
Vascular Niche

AbstractDegeneration of motor neurons, glial cell reactivity, and vascular alterations in the CNS are important neuropathological features of amyotrophic lateral sclerosis (ALS). Immune cells trafficking from the blood also infiltrate the affected CNS parenchyma and contribute to neuroinflammation. Mast cells (MCs) are hematopoietic-derived immune cells whose precursors differentiate upon migration into tissues. Upon activation, MCs undergo degranulation with the ability to increase vascular permeability, orchestrate neuroinflammation and modulate the neuroimmune response. However, the prevalence, pathological significance, and pharmacology of MCs in the CNS of ALS patients remain largely unknown. In autopsy ALS spinal cords, we identified for the first time that MCs express c-Kit together with chymase, tryptase, and Cox-2 and display granular or degranulating morphology, as compared with scarce MCs in control cords. In ALS, MCs were mainly found in the niche between spinal motor neuron somas and nearby microvascular elements, and they displayed remarkable pathological abnormalities. Similarly, MCs accumulated in the motor neuron-vascular niche of ALS murine models, in the vicinity of astrocytes and motor neurons expressing the c-Kit ligand stem cell factor (SCF), suggesting an SCF/c-Kit-dependent mechanism of MC differentiation from precursors. Mechanistically, we provide evidence that fully differentiated MCs in cell cultures can be generated from the murine ALS spinal cord tissue, further supporting the presence of c-Kit+ MC precursors. Moreover, intravenous administration of bone marrow-derived c-Kit+ MC precursors infiltrated the spinal cord in ALS mice but not in controls, consistent with aberrant trafficking through a defective microvasculature. Pharmacological inhibition of c-Kit with masitinib in ALS mice reduced the MC number and the influx of MC precursors from the periphery. Our results suggest a previously unknown pathogenic mechanism triggered by MCs in the ALS motor neuron-vascular niche that might be targeted pharmacologically.

The control of rostrocaudal pattern in the developing spinal cord: specification of motor neuron subtype identity is initiated by signals from paraxial mesoderm

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 969-982 ◽  
Author(s):  
M. Ensini ◽  
T.N. Tsuchida ◽  
H.G. Belting ◽  
T.M. Jessell
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Neural Tube ◽  
Motor Behavior ◽  
Neural Tube Closure ◽  
Paraxial Mesoderm ◽  
Homeodomain Protein ◽  
Mesodermal Cell ◽  
Developing Spinal Cord

The generation of distinct classes of motor neurons is an early step in the control of vertebrate motor behavior. To study the interactions that control the generation of motor neuron subclasses in the developing avian spinal cord we performed in vivo grafting studies in which either the neural tube or flanking mesoderm were displaced between thoracic and brachial levels. The positional identity of neural tube cells and motor neuron subtype identity was assessed by Hox and LIM homeodomain protein expression. Our results show that the rostrocaudal identity of neural cells is plastic at the time of neural tube closure and is sensitive to positionally restricted signals from the paraxial mesoderm. Such paraxial mesodermal signals appear to control the rostrocaudal identity of neural tube cells and the columnar subtype identity of motor neurons. These results suggest that the generation of motor neuron subtypes in the developing spinal cord involves the integration of distinct rostrocaudal and dorsoventral patterning signals that derive, respectively, from paraxial and axial mesodermal cell groups.

scholarly journals Contemporary Circulating Enterovirus D68 Strains Infect and Undergo Retrograde Axonal Transport in Spinal Motor Neurons Independent of Sialic Acid

2019 ◽  
Vol 93 (16) ◽  
Author(s):  
Alison M. Hixon ◽  
Penny Clarke ◽  
Kenneth L. Tyler
Keyword(s):  
Sialic Acid ◽  
Motor Neuron ◽  
Axonal Transport ◽  
Motor Neurons ◽  
The United States ◽  
Retrograde Axonal Transport ◽  
Spinal Motor Neurons ◽  
Acute Flaccid Myelitis ◽  
Spinal Motor ◽  
Enterovirus D68

ABSTRACTEnterovirus D68 (EV-D68) is an emerging virus that has been identified as a cause of recent outbreaks of acute flaccid myelitis (AFM), a poliomyelitis-like spinal cord syndrome that can result in permanent paralysis and disability. In experimental mouse models, EV-D68 spreads to, infects, and kills spinal motor neurons following infection by various routes of inoculation. The topography of virus-induced motor neuron loss correlates with the pattern of paralysis. The mechanism(s) by which EV-D68 spreads to target motor neurons remains unclear. We sought to determine the capacity of EV-D68 to spread by the neuronal route and to determine the role of known EV-D68 receptors, sialic acid and intracellular adhesion molecule 5 (ICAM-5), in neuronal infection. To do this, we utilized a microfluidic chamber culture system in which human induced pluripotent stem cell (iPSC) motor neuron cell bodies and axons can be compartmentalized for independent experimental manipulation. We found that EV-D68 can infect motor neurons via their distal axons and spread by retrograde axonal transport to the neuronal cell bodies. Virus was not released from the axons via anterograde axonal transport after infection of the cell bodies. Prototypic strains of EV-D68 depended on sialic acid for axonal infection and transport, while contemporary circulating strains isolated during the 2014 EV-D68 outbreak did not. The pattern of infection did not correspond with the ICAM-5 distribution and expression in either human tissue, the mouse model, or the iPSC motor neurons.IMPORTANCEEnterovirus D68 (EV-D68) infections are on the rise worldwide. Since 2014, the United States has experienced biennial spikes in EV-D68-associated acute flaccid myelitis (AFM) that have left hundreds of children paralyzed. Much remains to be learned about the pathogenesis of EV-D68 in the central nervous system (CNS). Herein we investigated the mechanisms of EV-D68 CNS invasion through neuronal pathways. A better understanding of EV-D68 infection in experimental models may allow for better prevention and treatment strategies of EV-D68 CNS disease.

(−)-Deprenyl Attenuates Spinal Motor Neuron Degeneration and Associated Locomotor Deficits in Rats Subjected to Spinal Cord Ischemia

1998 ◽  
Vol 149 (1) ◽  
pp. 123-129 ◽  
Author(s):  
R. Ravikumar ◽  
M.K. Lakshmana ◽  
B.S. Shankaranarayana Rao ◽  
B.L. Meti ◽  
P.N. Bindu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Spinal Cord Ischemia ◽  
Motor Neuron Degeneration ◽  
Neuron Degeneration ◽  
Spinal Motor Neuron ◽  
Spinal Motor ◽  
Locomotor Deficits
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