Single-cell RNA sequencing analysis of iPSC-derived motor neurons from an ALS patient carrying ATXN2 intermediate repeat expansions and a healthy control
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE224582 | GEO | 2024/07/16
REPOSITORIES: GEO
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Project description:Intermediate-length repeat expansions in ATAXIN-2 (ATXN2) are a strong genetic risk factor for amyotrophic lateral sclerosis (ALS). At the molecular level, ATXN2 intermediate expansions enhance TDP-43 toxicity and pathology. However, whether this triggers ALS pathogenesis at the cellular and functional level remains unknown. Here, we developed a human iPSC-derived model to investigate whether motor neurons derived from ALS patients carrying ATXN2 intermediate repeat expansions are transcriptomically distinct from healthy controls. For that, we performed RNA sequencing of motor neurons derived from 5 ATXN2-ALS iPSC lines and 5 healthy controls (HC).
2024-07-16 | GSE224578 | GEO
Project description:Intermediate-length repeat expansions in ATAXIN-2 (ATXN2) are a strong genetic risk factor for amyotrophic lateral sclerosis (ALS). At the molecular level, ATXN2 intermediate expansions enhance TDP-43 toxicity and pathology. However, whether this triggers ALS pathogenesis at the cellular and functional level remains unknown. Our study shows that microglial cells might contribute to ALS-related pathology observed in mice carrying ATXN2 intermediate repeat expansions (Q33) in an ALS background (TDP-43). To investigate whether ATXN2-Q33;TDP-43 spinal cord microglia are transcriptomically different from non transgenic counterparts, we performed RNA sequencing of sorted microglial cells from knock-in (ATXN2-Q33;TDP-43) as well as non-transgenic (NTg) mice.
2024-07-16 | GSE224581 | GEO
Project description:Intermediate-length repeat expansions in ATAXIN-2 (ATXN2) are a strong genetic risk factor for amyotrophic lateral sclerosis (ALS). At the molecular level, ATXN2 intermediate expansions enhance TDP-43 toxicity and pathology. However, whether this triggers ALS pathogenesis at the cellular and functional level remains unknown. To investigate gene expression changes and deregulated pathways caused by ataxin-2 intermediate repeat expansions in presence/absence of mutant TDP-43, we performed RNA sequencing of whole spinal cords from knock-in mice harboring ATXN2 and TDP-43 human transgenes as well as non-transgenic mice (NTg)
2024-07-16 | GSE224580 | GEO
Project description:Human Ataxin-2 (ATXN2) gene locus variants have been associated with obesity, diabetes mellitus type 1 and hypertension in genome-wide association studies, while mouse studies showed the knock-out of Atxn2 to lead to obesity, insulin resistance and dyslipidemia. Intriguingly, the deficiency of ATXN2 protein orthologues in yeast and flies rescues the neurodegeneration process triggered by TDP-43 and Ataxin-1 toxicity. To understand the molecular effects of ATXN2 deficiency by unbiased approaches, we quantified the global proteome and metabolome of Atxn2-knock-out mice with label-free mass spectrometry. In liver tissue, significant downregulations of the proteins ACADS, ALDH6A1, ALDH7A1, IVD, MCCC2, PCCA, OTC, together with bioinformatic enrichment of downregulated pathways for branched chain and other amino acid metabolism, fatty acids and citric acid cycle were observed. Statistical trends in the cerebellar proteome and in the metabolomic profiles supported these findings. They are in good agreement with recent claims that PBP1, the yeast orthologue of ATXN2, sequestrates the nutrient sensor TORC1 in periods of cell stress. Overall, ATXN2 appears to modulate nutrition and metabolism, and its activity changes are determinants of growth excess or cell atrophy.
2016-02-08 | PXD003155 | Pride
Project description:ATXN2 has emerged as an exciting therapeutic target for neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia type 2 (SCA2), as lowering its levels via genomic knockout or anti-sense oligonucleotide (ASO) treatment has been shown to mitigate disease phenotypes and led to a current clinical trial of ATXN2 ASOs for treatment of ALS in humans. To identify additional ways to lower ataxin‑2 protein levels, we performed a genome-wide fluorescence activated cell sorting (FACS)-based CRISPR screen in human cells and identified multiple components of the lysosomal vacuolar ATPase (v‑ATPase) as modifiers of ataxin‑2 levels. This dataset contains the RNA-sequencing data and CRISPR screen data used to support the conclusions from this study.
2022-10-18 | GSE189417 | GEO
Project description:Microsatellite repeat expansion disease loci can exhibit pleiotropic clinical and biological effects depending on repeat length. Large expansions in C9orf72 (100s-1000s of units) are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). However, whether intermediate expansions also contribute to neurodegenerative disease is not well understood. Several studies have identified intermediate repeats in Parkinson’s disease patients, but the association was not found in autopsy confirmed cases. We hypothesized that intermediate C9orf72 repeats are a genetic risk factor for corticobasal degeneration (CBD), a neurodegenerative disease that can be clinically similar to Parkinson’s but has distinct tau protein pathology. Indeed, intermediate C9orf72 repeats were significantly enriched in autopsy-proven CBD (n=354 cases, odds ratio=3.59, p-value=0.00024). While large C9orf72 repeat expansions are known to decrease C9orf72 expression, intermediate C9orf72 repeats result in increased C9orf72 expression in human brain tissue and CRISPR/cas9 knockin iPSC derived neural progenitor cells. In contrast to cases of FTD/ALS with large C9orf72 expansions, CBD with intermediate C9orf72 repeats was not associated with pathologic RNA foci or dipeptide repeat protein aggregates. Knock-in cells with intermediate repeats exhibit numerous changes in gene expression pathways relating to vesicle trafficking and autophagy. Additionally, overexpression of C9orf72 without the repeat expansion leads to defects in autophagy under nutrient starvation conditions. These results raise the possibility that therapeutic strategies to reduce C9orf72 expression may be beneficial for the treatment of CBD.
2019-09-17 | GSE133323 | GEO
Project description:Ataxin-2 (ATXN2) is a gene implicated in spinocerebellar ataxia type II (SCA2), amyotrophic lateral sclerosis (ALS) and Parkinsonism. The encoded protein is a therapeutic target for ALS and related conditions. ATXN2 (or Atx2 in insects) functions in translational regulation, mRNA stability, and in the assembly of mRNP-granules, a process mediated by intrinsically disordered regions (IDRs). Previous work has shown that the LSm (Like-Sm) domain of Atx2, which mediates translational activation of some target mRNAs, antagonizes mRNP-granule assembly. Here we advance these findings through a series of experiments on Drosophila and human Ataxin-2 proteins. Results of Targets of RNA-Binding Proteins Identified by Editing (TRIBE) experiments indicate that a polyA-binding protein (PABP) interacting, PAM2 motif of Ataxin-2 may be a major determinant of the mRNA content of Ataxin-2 mRNP granules. Co-localization and co-immunoprecipitation analyses show that structured interactions between Ataxin-2 and PABP additionally help determine protein components of Ataxin-2-associated mRNP granules and contribute to Ataxin-2’s association with stress granules. Finally, in vivo experiments in Drosophila indicate that while the Atx2-LSm domain protects against neurodegeneration, structured PAM2- and unstructured IDR- interactions both promote degeneration. Taken together the data: (a) lead to a proposal for how Ataxin-2 interactions are remodelled during different stages of translational control; (b) show how structured and non-structured interactions of Ataxin-2 contribute differently to the specificity and efficiency of RNP granule condensation; and (c) demonstrate that the Ataxin-2 protein contains multiple activities that may respectively prevent or promote neurodegeneration.
2024-04-22 | GSE196739 | GEO
Project description:Spinocerebellar Ataxia Type 2 (SCA2) is caused by expansion of a polyglutamine encoding triplet repeat in the human ATXN2 gene beyond (CAG)31. This is thought to mediate toxic gain-of-function by protein aggregation, and affect RNA processing, resulting in degenerative processes affecting preferentially cerebellar neurons. As a faithful animal model, we generated a knock-in mouse replacing the single CAG of murine Atxn2 with CAG42, a frequent patient genotype. This expansion size was inherited stably. The mice showed phenotypes with reduced weight and later motor incoordination. Although brain Atxn2 mRNA became elevated, soluble ATXN2 protein levels diminished over time, which might explain partial loss-of-function effects. Deficits in soluble ATXN2 protein correlated with the appearance of insoluble ATXN2, a progressive feature in cerebellum possibly reflecting toxic gains-of-function. Since in vitro ATXN2 overexpression was known to reduce levels of its protein interactor PABPC1, we studied expansion effects on PABPC1. In cortex, PABPC1 transcript, soluble and insoluble protein levels were increased. In more vulnerable cerebellum the progressive insolubility of PABPC1 was accompanied by decreased soluble protein levels, with PABPC1 mRNA showing no compensatory increase. The sequestration of PABPC1 into insolubility by ATXN2 function gains was validated in human cell culture. To understand consequences on mRNA processing, transcriptome profiles at medium and old age in three different tissues were studied and demonstrated selective induction of Fbxw8 in old cerebellum. Fbxw8 is encoded next to the Atxn2 locus and was shown in vitro to decrease the level of expanded insoluble ATXN2 protein. In conclusion, our data support the concept that expanded ATXN2 undergoes progressive insolubility and affects PABPC1 by a toxic gain-of-function mechanism with tissue-specific effects, which may be partially alleviated by the induction of FBXW8. Factorial design comparing Atxn2 knock-in mice with wild type littermates in three different tissues (brainstem, cerebellum, liver)
2012-07-24 | E-GEOD-39640 | biostudies-arrayexpress
Project description:Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder, which is caused by an unstable CAG-repeat expansion in the SCA2 gene, that encodes a polyglutamine tract (polyQ-tract) expansion in ataxin-2 protein (ATXN2). The RNA-binding protein ATXN2 interacts with the poly(A)-binding protein PABPC1, localizing to ribosomes at the rough endoplasmic reticulum or to polysomes. Under cell stress ATXN2 and PABPC1 show redistribution to stress granules where mRNAs are kept away from translation and from degradation. It is unknown whether ATXN2 associates preferentially with specific mRNAs or how it modulates their processing. Here, we investigated Atxn2 knock-out (Atxn2-/-) mouse liver, cerebellum and midbrain regarding their RNA profile, employing oligonucleotide microarrays for screening and RNA deep sequencing for validation. Modest ~1.4-fold upregulations were observed for the level of many mRNAs encoding ribosomal proteins and other translation pathway factors. Quantitative reverse transcriptase PCR and immunoblots in liver tissue confirmed these effects and demonstrated an inverse correlation also with PABPC1 mRNA and protein. ATXN2 deficiency also enhanced phosphorylation of the ribosomal protein S6, while impairing the global protein synthesis rate, suggesting a block between the enhanced translation drive and the impaired execution. Furthermore, ATXN2 overexpression and deficiency retarded cell cycle progression. ATXN2 mRNA levels showed a delayed phasic twofold increase under amino acid and serum starvation, similar to ATXN3, but different from motor neuron disease genes MAPT and SQSTM1. ATXN2 mRNA levels depended particularly on mTOR signalling. Altogether the data implicate ATXN2 in the adaptation of mRNA translation and cell growth to nutrient availability and stress. Factorial design comparing ataxin-2 knock-out mice with wild type littermates in three different tissues (midbrain, cerebellum, liver) and 3 different ages.
2014-10-31 | E-GEOD-55177 | biostudies-arrayexpress
Project description:Transactive Response DNA-binding protein 43 (TDP-43) is a multifunctional nuclear protein ubiquitously expressed in all tissues. Although it is primarily nuclear, Amyotrophic Lateral Sclerosis (ALS) patients frequently present with cytoplasmic aggregates of TDP-43 in motor neurons on post-mortem examination. Although only about 5% of all ALS patients have a TARDBP mutation (Ghasemi and Brown 2018; Ingre et al. 2015), which is known to cause these insoluble cytoplasmic aggregates, 97% of ALS patients will develop cytoplasmic, insoluble TDP-43 aggregates regardless of whether they have a mutation in TARDBP or not (Ling et al. 2013). Overexpression of wild-type TDP-43 has previously been shown to be a valid model of inducing neurotoxicity as well as a limited amount of cytoplasmic re-localization and aggregation characteristic of ALS (Elden et al. 2010; Wils et al. 2010). In the search for modifiers of toxicity as conferred by TDP-43 overexpression in these models, knockout of Ataxin-2 (ATXN2) was proposed as a protective intervention in the context of TDP-43 perturbation in non-human model systems (Elden et al. 2010, Becker et al. 2017). This promising finding had not previously been validated in a human motor neuron system, nor had a thorough investigation been conducted to determine the mechanism of neuroprotection that ATXN2 knockout employs to drive the therapeutic effect. This sequencing study examines both ATXN2 intact and ATXN2 knockout motor neurons in the context of TDP-43 perturbation to explore global transcriptomic changes that arise from these changes in cellular state that are associated with progression of ALS (ATXN2 intact) and what pathways could be implicated in protection from ALS-associated neurodegeneration (ATXN2 Knockout).
2024-03-23 | GSE261875 | GEO