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Astrocyte-encoded positional cues maintain sensorimotor circuit integrity

ABSTRACT: Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded Semaphorin3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a led to dysregulated α−motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α−but not of adjacent γ−motor neurons. Additionally, a subset of TrkA+ sensory afferents projected to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement.

ORGANISM(S): Mus musculus

PROVIDER: GSE55054 | GEO | 2014/05/02

SECONDARY ACCESSION(S): PRJNA238347

REPOSITORIES: GEO

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Astrocyte-encoded positional cues maintain sensorimotor circuit integrity

Project description:Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded Semaphorin3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a led to dysregulated α−motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α−but not of adjacent γ−motor neurons. Additionally, a subset of TrkA+ sensory afferents projected to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement. 12 total samples consisting of three biological replicates each of flow sorted postnatal day 7 dorsal spinal cord astrocytes, ventral spinal cord astrocytes, dorsal SC non astrocytes, and ventral SC non astrocytes

2014-05-02 | E-GEOD-55054 | biostudies-arrayexpress

Astrocyte allocation during brain development is controlled by Tcf4-mediated fate restriction

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2018-05-01 | GSE111148 | GEO

Perturbations of the proteome in primary astrocytes from the hSOD1(G93A) ALS mouse model

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2022-02-17 | PXD026576 | Pride

FUS-ALS hiPSC-derived astrocytes impair human motor units through both gain-of-toxicity and loss-of-support mechanisms

Project description:Non-neuronal cells, including astrocytes, play a crucial role in the selective motor neuron pathology in amyotrophic lateral sclerosis (ALS). How astrocytes exactly contribute to the disease is not fully elucidated. Therefore, we characterised human induced pluripotent stem cell (hiPSC)-derived astrocytes from FUS-ALS patients, and incorporated these astrocytes into a human motor unit model to investigate the astrocytic effect on hiPSC-derived motor neuron network and neuromuscular junctions (NMJs). We observed a dysregulation of astrocyte homeostasis, which resulted in a FUS-ALS-mediated increase in reactivity and secretion of pro-inflammatory cytokines. Upon coculture with motor neurons and myotubes, we detected a cytotoxic effect on motor neuron-neurite morphology and outgrowth, as well as on NMJ formation and functionality, which was improved or fully rescued by isogenic control astrocytes. We conclude that mutant astrocytes have both a gain-of-toxicity and loss-of-support function in ALS, ultimately contributing to the disruption of motor neuron homeostasis, intercellular networks and NMJs.

2023-01-19 | GSE196219 | GEO

Embryonic stem cell-derived brainstem and spinal astrocyte-like cells develop a neurotoxic phenotype in vitro following clinically relevant pro-inflammatory stimulation

Project description:Traumatic axonal injury (TAI) in the brainstem carries a particularly poor prognosis. Although the role of neuroinflammation in this process is incompletely characterized, astrogliosis has been shown to coincide with TAI. Moreover, astrogliotic forebrain astrocytes were recently shown to confer a toxic effect on neurons. We sought to assess if ventral brainstem- or rostroventral spinal astrocytes exert similar effects on motor neurons in vitro. We derived brainstem/rostroventral spinal astrocyte-like cells (ES-astrocytes) and motor neurons using directed differentiation of embryonic stem cells (ES). ES-astrocyte identity was assessed using RNA-sequencing, immunocytochemistry, and comparison with primary subventricular zone-astrocytes. We activated the ES-astrocytes using the neurotoxicity-eliciting cytokines interleukin- (IL-) 1α and tumor necrosis factor-(TNF-)α. In co-cultures with reactive ES-astrocytes and motor neurons, we demonstrated neurotoxic ES-astrocyte activity, similarly to what has previously been shown for other central nervous system (CNS) regions. When exposed to IL-1β and IL-6, two neuroinflammatory cytokines found in the cerebrospinal fluid and serum proteome following severe traumatic brain injury (TBI), ES-astrocytes exerted similar effects on motor neurons. This demonstrates that ventral brainstem and rostroventral spinal cord astrocytes can exert neurotoxic effects in vitro. This highlights the importance of neuroinflammation as a secondary injury mechanism following neurotrauma, and presents a possible treatment avenue to improve neuronal survival in particularly vulnerable CNS regions following TAI.

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Project description:Mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (ALS) are yet unclear. Specific deletion of the ER-component membralin in astrocytes manifested postnatal motor defects and lethality in mice, causing the accumulation of extracellular glutamate through reducing the glutamate transporter EAAT2. Restoring EAAT2 levels in membralin KO astrocytes limited astrocyte-dependent excitotoxicity in motor neurons. Transcriptomic profiles from mouse astrocytic membralin KO motor cortex indicateed significant perturbation in KEGG pathway components related to ALS, including downregulation of Eaat2 and upregulation of Tnfrsf1a. Changes in gene expression with membralin deletion also overlapped with mouse ALS models and reactive astrocytes. Our results shown that activation of TNF receptor (TNFR1)-NFkB pathway known to suppress Eaat2 transcription was upregulated with membralin deletion. Further, reduced membralin and EAAT2 levels correlated with disease progression in spinal cord from SOD1-mutant mouse models, and reductions in membralin/EAAT2 were observed in human ALS spinal cord. Importantly, overexpression of membralin in SOD1G93A astrocytes decreased TNFR1 levels and increased EAAT2 expression, and improved motor neuron survival. Importantly, upregulation of membralin in SOD1G93A mice significantly prolonged mouse survival. Together, our study provides a mechanism for ALS pathogenesis where membralin limits glutamatergic neurotoxicity, suggesting that modulating membralin has potential in ALS therapy

2019-05-07 | GSE130763 | GEO

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