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Human iPSC-derived astrocytes from ALS patients with mutated C9ORF72 show increased oxidative stress and neurotoxicity

ABSTRACT: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons (MNs). It was shown that human astrocytes with mutations in genes associated with ALS, like C9orf72 (C9) or SOD1, reduce survival of MNs. Astrocyte toxicity may be related to their dysfunction or the release of neurotoxic factors. We used human induced pluripotent stem cell-derived astrocytes from ALS patients carrying C9orf72 mutations and non-affected donors. We utilized these cells to investigate astrocytic induced neuronal toxicity, changes in astrocyte transcription profile as well as changes in secretome profiles. We report that C9-mutated astrocytes are toxic to MNs via soluble factors. The toxic effects of astrocytes are positively correlated with the length of astrocyte propagation in culture, consistent with the age-related nature of ALS. We show that C9-mutated astrocytes downregulate the secretion of several antioxidant proteins. In line with these findings, we show increased astrocytic oxidative stress and senescence. Importantly, media conditioned by C9-astrocytes increased oxidative stress in wild type MNs. Our results suggest that dysfunction of C9-astrocytes leads to oxidative stress of themselves and MNs, which probably contributes to neurodegeneration. Our findings suggest that therapeutic strategies in familial ALS must not only target MNs but also focus on astrocytes to abrogate nervous system injury.

ORGANISM(S): Homo sapiens

PROVIDER: GSE142730 | GEO | 2020/06/01

REPOSITORIES: GEO

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iPSC derived motor neuron cultures from C9ORF72 carriers

Project description:Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative condition characterized by loss of motor neurons in the brain and spinal cord. Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9ORF72 gene are the most common cause of the familial form of ALS (C9-ALS), as well as frontotemporal lobar degeneration and other neurological diseases. How the repeat expansion causes disease remains unclear, with both loss of function (haploinsufficiency) and gain of function (either toxic RNA or protein products) proposed. We report a cellular model of C9-ALS with motor neurons differentiated from induced pluripotent stem cells (iPSCs) derived from ALS patients carrying the C9ORF72 repeat expansion. No significant loss of C9ORF72 expression was observed, and knockdown of the transcript was not toxic to cultured human motor neurons. Transcription of the repeat was increased, leading to accumulation of GGGGCC repeat–containing RNA foci selectively in C9-ALS iPSC-derived motor neurons. Repeat-containing RNA foci colocalized with hnRNPA1 and Pur-?, suggesting that they may be able to alter RNA metabolism. C9-ALS motor neurons showed altered expression of genes involved in membrane excitability including DPP6, and demonstrated a diminished capacity to fire continuous spikes upon depolarization compared to control motor neurons. Antisense oligonucleotides targeting the C9ORF72 transcript suppressed RNA foci formation and reversed gene expression alterations in C9-ALS motor neurons. These data show that patient-derived motor neurons can be used to delineate pathogenic events in ALS. Transcriptome profiling from iPSC derived motor neurons compared to controls

2013-11-07 | E-GEOD-52202 | biostudies-arrayexpress

Micro-RNAs secreted through astrocyte-derived extracellular vesicles cause neuronal network degeneration in C9orf72 ALS

Project description:Background: Astrocytes regulate neuronal function, synaptic formation and maintenance partly through secreted extracellular vesicles (EVs). In amyotrophic lateral sclerosis (ALS) astrocytes display a toxic phenotype that contributes to motor neuron (MN) degeneration. Methods: We used human induced astrocytes (iAstrocytes) from 3 ALS patients carrying C9orf72 mutations and 3 non-affected donors to investigate the role of astrocyte-derived EVs (ADEVs) in ALS astrocyte toxicity. ADEVs were isolated from iAstrocyte conditioned medium via ultracentrifugation and resuspended in fresh astrocyte medium before testing ADEV impact on HB9-GFP+ mouse motor neurons (Hb9-GFP+ MN). We used post-mortem brain and spinal cord tissue from 3 sporadic ALS and 3 non-ALS cases for PCR analysis. Findings: We report that EV formation and miRNA cargo are dysregulated in C9ORF72-ALS iAstrocytes and this affects neurite network maintenance and MN survival in vitro. In particular, we have identified downregulation of miR-494-3p, a negative regulator of semaphorin 3A (SEMA3A). We show here that by restoring miR-494-3p levels through expression of an engineered miRNA mimic we can downregulate Sema3A levels in MNs and increases MN survival in vitro. Consistently, we also report lower levels of mir-494-3p and higher levels of SEMA3A in cortico-spinal tract tissue isolated from sporadic ALS donors, thus demonstrating the pathological importance of this pathway in MNs and its therapeutic potential. Interpretation: ALS ADEVs and their miRNA cargo are involved in MN death in ALS and we have identified miR-494-3p as a potential therapeutic target.

2019-01-08 | GSE122640 | GEO

iPSC derived motor neuron cultures from C9ORF72 carriers

Project description:Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative condition characterized by loss of motor neurons in the brain and spinal cord. Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9ORF72 gene are the most common cause of the familial form of ALS (C9-ALS), as well as frontotemporal lobar degeneration and other neurological diseases. How the repeat expansion causes disease remains unclear, with both loss of function (haploinsufficiency) and gain of function (either toxic RNA or protein products) proposed. We report a cellular model of C9-ALS with motor neurons differentiated from induced pluripotent stem cells (iPSCs) derived from ALS patients carrying the C9ORF72 repeat expansion. No significant loss of C9ORF72 expression was observed, and knockdown of the transcript was not toxic to cultured human motor neurons. Transcription of the repeat was increased, leading to accumulation of GGGGCC repeat–containing RNA foci selectively in C9-ALS iPSC-derived motor neurons. Repeat-containing RNA foci colocalized with hnRNPA1 and Pur-α, suggesting that they may be able to alter RNA metabolism. C9-ALS motor neurons showed altered expression of genes involved in membrane excitability including DPP6, and demonstrated a diminished capacity to fire continuous spikes upon depolarization compared to control motor neurons. Antisense oligonucleotides targeting the C9ORF72 transcript suppressed RNA foci formation and reversed gene expression alterations in C9-ALS motor neurons. These data show that patient-derived motor neurons can be used to delineate pathogenic events in ALS.

2013-11-07 | GSE52202 | GEO

Divergent impacts of C9orf72 repeat expansion on neurons and glia in ALS and FTD (snRNA-seq)

Project description:Neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), are strongly influenced by inherited genetic variation, but environmental and epigenetic factors also play key roles in the course of these diseases. A hexanucleotide repeat expansion in the C9orf72 (C9) gene is the most common genetic cause of ALS and FTD. To determine the cellular alterations associated with the C9 repeat expansion, we performed single nucleus transcriptomics (snRNA-seq) and epigenomics (snATAC-seq) in postmortem samples of motor and frontal cortices from C9-ALS and C9-FTD donors. We found pervasive alterations of gene expression across multiple cortical cell types in C9-ALS, with the largest number of affected genes in astrocytes and excitatory neurons. Astrocytes increased expression of markers of activation and pathways associated with structural remodeling. Excitatory neurons in upper and deep layers increased expression of genes related to proteostasis, metabolism, and protein expression, and decreased expression of genes related to neuronal function. Epigenetic analyses revealed concordant changes in chromatin accessibility, histone modifications, and gene expression in specific cell types. C9-FTD patients had a distinct pattern of changes, including loss of neurons in frontal cortex and altered expression of thousands of genes in astrocytes and oligodendrocyte-lineage cells. Overall, these findings demonstrate a context-dependent molecular disruption in C9-ALS and C9-FTD, resulting in distinct effects across cell types, brain regions, and disease phenotypes.

2023-07-17 | GSE219280 | GEO

Divergent impacts of C9orf72 repeat expansion on neurons and glia in ALS and FTD (snATAC-seq)

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Divergent impacts of C9orf72 repeat expansion on neurons and glia in ALS and FTD (bulk RNA-seq)

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Divergent impacts of C9orf72 repeat expansion on neurons and glia in ALS and FTD (bulk H3K27ac ChIP-seq)

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Reactive astrocytes in ALS models display dysregulated intron retention

Project description:Reactive astrocytes are implicated in Amyotrophic Lateral Sclerosis (ALS), although the mechanisms controlling reactive transformation are unknown. We show that decreased intron retention (IR) is common to human induced pluripotent stem cell (hiPSC)-derived astrocytes carrying VCP, C9orf72 and SOD1 ALS-causing mutations as well as astrocytes stimulated to undergo reactive transformation. Notably, transcripts with decreased IR and increased expression are overrepresented in reactivity processes including cell-adhesion, stress-response, and immune-activation. We examined astrocyte translatome sequencing (TRAP-seq) from a SOD1 mouse model, which revealed a significant number of transcripts with reduced IR in ALS are upregulated in translation. Using nucleo-cytoplasmic fractionation of VCP astrocytes coupled with mRNA sequencing and proteomics, we identify that decreased IR in nuclear-detained transcripts is associated with increased cytoplasmic expression of genes and proteins encoding regulators of reactivity - indicating nuclear-to-cytoplasmic translocation and translation of spliced reactivity-related transcripts. These results provide novel insights into the molecular factors controlling the reactive transformation of ALS astrocytes.

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Progressive motor neuron pathology and the role of astrocytes in a human stem cell model of VCP-related ALS [terminally differentiated iPSC-derived astrocytes]

Project description:Motor neurons (MNs) and astrocytes (ACs) are implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), but their interaction and the sequence of molecular events leading to MN death remain unresolved. Herewe optimized directed differentiation of induced pluripotent stem cells (iPSCs) into highly enriched (>85%) functional populations of spinal cord MNs and ACs. We identifysignificantlyincreased cytoplasmic TDP-43 and ER stress as primary pathogenic events in patient-specific valosin-containing protein (VCP)-mutant MNs, with secondary mitochondrial dysfunction and oxidative stress. Cumulatively these cellular stresses result in synaptic pathology and cell death in VCP-mutant MNs. We additionallyidentify a cell-autonomous VCP-mutant AC survival phenotype, which is not attributable to the same molecular pathology occurring in VCP-mutant MNs. Finally, through iterative co-culture experiments, we uncover non-cell-autonomous effects of VCP-mutant ACs on both control and mutant MNs. This work elucidates molecular events and cellular interplay thatcould guide future therapeutic strategies in ALS.

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Progressive motor neuron pathology and the role of astrocytes in a human stem cell model of VCP-related ALS

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