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

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.

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Single-cell transcriptomic analysis of the adult mouse spinal cord

10.1101/2020.03.16.992958 ◽

2020 ◽

Cited By ~ 1

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.

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

Development ◽

10.1242/dev.126.12.2727 ◽

1999 ◽

Vol 126 (12) ◽

pp. 2727-2737 ◽

Cited By ~ 4

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.

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

10.1101/690859 ◽

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.

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

Developmental Biology ◽

10.1016/j.ydbio.2019.07.017 ◽

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

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

Experimental Neurology ◽

10.1006/exnr.1997.6682 ◽

1998 ◽

Vol 149 (1) ◽

pp. 123-129 ◽

Cited By ~ 12

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

Development ◽

10.1242/dev.120.1.25 ◽

1994 ◽

Vol 120 (1) ◽

pp. 25-36 ◽

Cited By ~ 11

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.

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Motor neurons and the generation of spinal motor neuron diversity

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2014.00293 ◽

2014 ◽

Vol 8 ◽

Cited By ~ 84

Author(s):

Nicolas Stifani

Keyword(s):

Motor Neuron ◽

Motor Neurons ◽

Spinal Motor Neuron ◽

Spinal Motor ◽

Neuron Diversity

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Identification of 17 highly expressed genes within mouse lumbar spinal cord anterior horn region from an in-situ hybridization atlas of 3430 genes: implications for motor neuron disease

Neurology International ◽

10.4081/ni.2014.5367 ◽

2014 ◽

Vol 6 (2) ◽

Cited By ~ 8

Author(s):

Michael A. Meyer

Keyword(s):

Spinal Cord ◽

Motor Neuron ◽

Motor Neuron Disease ◽

Motor Neurons ◽

Ventral Horn ◽

Janus Kinase ◽

Anterior Horn ◽

Lumbar Spinal Cord ◽

Spinal Motor ◽

Lumbar Spinal

In an effort to find possible new gene candidates involved in the causation of amyotrophic lateral sclerosis (ALS), a prior version of the on-line brain gene expression atlas GENSAT was extensively searched for selectively intense expression within spinal motor neurons. Using autoradiographic data of in-situ hybridization from 3430 genes, a search for selectively intense activity was made for the anterior horn region of murine lumbar spinal cord sectioned in the axial plane. Of 3430 genes, a group of 17 genes was found to be highly expressed within the anterior horn suggesting localization to its primary cellular constituent, the alpha spinal motor neuron. For some genes, an inter-relationship to ALS was already known, such as for heavy, medium, and light neurofilaments, and peripherin. Other genes identified include: Gamma Synuclein, GDNF, SEMA3A, Extended Synaptotagmin-like protein 1, LYNX1, HSPA12a, Cadherin 22, PRKACA, TPPP3 as well as Choline Acetyltransferase, Janus Kinase 1, and the Motor Neuron and Pancreas Homeobox 1. Based on this study, Fibroblast Growth Factor 1 was found to have a particularly selective and intense localization pattern to the ventral horn and may be a good target for development of motor neuron disease therapies; further research is needed.

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