Molecular pathways involved in neuronal degeneration of polyglutamine mouse models
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE3634 | GEO | 2006/11/18
SECONDARY ACCESSION(S): PRJNA93749
REPOSITORIES: GEO
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Project description:To elucidate the pathways involved in the SCA7 retinal degeneration, we used DNA GeneChips and compared the gene expression profiles of the mutant mice (R7E) and the control ones (R7N). We performed these experiments at the onset stage of the disease (3w) as well as on the moderate one (9w) in order to correlate the transcriptional deregulations with the phenotype progression. We also compared the R6/2 mice vs wild type (wt) ones to identify between the deregulated transcripts the ones that were also differentially expressed in the R7E vs R7N mice. These common changes are likely caused by polyQ expansion independently of the protein context. Experiment Overall Design: Retina RNA was prepared from 4-6 animals from each mouse line. Each RNA sample was independently hybridized on a different Genehip.
2009-02-07 | E-GEOD-3634 | biostudies-arrayexpress
Project description:To determine if STAGA complex dysfunction affects chromatin remodeling in SCA7 cerebellar degeneration, we pursued unbiased ChIP-Seq analysis of histone 3 lysine 9 acetylation (H3K9ac), as this histone mark is an established indicator of open chromatin in the transcription regulatory regions of most genes. We studied SCA7 266Q knock-in mice which faithfully recapitulate a severe, rapidly progressive neurodegenerative phenotype involving the cerebellum. We detected altered H3K9ac in the promoter regions of 777 genes in the cerebellum of SCA7 266Q knock-in mice and wild-type littermate control mice, and noted that the vast majority of these chromatin alterations corresponded to markedly increased H3K9 promoter acetylation in genes expressed in the cerebellum of SCA7 model mice.
2021-02-04 | GSE166118 | GEO
Project description:Polyglutamine(polyQ) expansion of α1A voltage-dependent calcium channel (Cav2.1) is the causative mutation of spinocerebellar ataxia type 6 (SCA6). The C-terminal fragment (CTF) of Cav2.1 makes aggregates in the cytoplasm of SCA6 Purkinje cells and may relate to the pathogenesis. In order to identify genes associated with polyQ expansion and subcellular localization of CTF, we analyzed gene expression profiles of PC12 rat pheochromocytoma cells using Tet-off system.
2013-03-13 | GSE26933 | GEO
Project description:Spinocerebellar ataxia type 7 (SCA7) is a genetic neurodegenerative disorder caused by a CAG-polyglutamine repeat expansion. Purkinje cells (PCs) are central to the pathology of ataxias, but their low abundance in the cerebellum underrepresents their transcriptomes in sequencing assays. To address this issue, we developed a PC enrichment protocol and sequenced individual nuclei from mice and patients with SCA7. Single-nucleus RNA sequencing in SCA7-266Q mice revealed dysregulation of cell identity genes affecting glia and PCs. Specifically, genes marking zebrin-II PC subtypes accounted for the highest proportion of DEGs in symptomatic SCA7-266Q mice. These transcriptomic changes in SCA7-266Q mice were associated with increased numbers of inhibitory synapses as quantified by immunohistochemistry and reduced spiking of PCs in acute brain slices. Dysregulation of zebrin-II cell subtypes was the predominant signal in PCs of SCA7-266Q mice and was associated with the loss of zebrin-II striping in the cerebellum at motor symptom onset. We furthermore demonstrated zebrin-II stripe degradation in additional mouse models of polyglutamine ataxia and observed decreased zebrin-II expression in the cerebella of patients with SCA7. Our results suggest that a breakdown of zebrin subtype regulation is a shared pathological feature of polyglutamine ataxias.
2024-08-14 | GSE269430 | GEO
Project description:Polyglutamine(polyQ) expansion of ?1A voltage-dependent calcium channel (Cav2.1) is the causative mutation of spinocerebellar ataxia type 6 (SCA6). The C-terminal fragment (CTF) of Cav2.1 makes aggregates in the cytoplasm of SCA6 Purkinje cells and may relate to the pathogenesis. In order to identify genes associated with polyQ expansion and subcellular localization of CTF, we analyzed gene expression profiles of PC12 rat pheochromocytoma cells using Tet-off system. We exmined gene expression profiles of Tet-off PC12 cells using the following four recombinant C-terminal fragments (rCTFs): rCTF-Q13-NLS, rCTF-Q13-NES, rCTF-Q28-NLS and rCTF-Q28-NES. We obtained gene expression data of both Dox (+) and Dox (-) conditions for each CTF. All assays were performed in duplicate.
2013-03-13 | E-GEOD-26933 | biostudies-arrayexpress
Project description:Dentatorubral-pallidoluysian Atrophy (DRPLA) is a human polyQ disease caused by the expansion of a CAG strech in the atrophin-1 (at-1) gene. In all vertebrates, a second atrophin gene (at-2) is present and it encodes a related protein void of polyQ tracks. In D.melanogaster there is one conserved Atrophin (Atro) gene, ubiquitously expressed, which contains all functional domains of vertebrate Atrophins, including two polyQ stretches. To understand to what extent transcriptional alterations cause neurodegeneration and are linked to the normal functions of Atrophin, we performed a genome wide transcriptional profiling in our Drosophila models, focusing on primary events that precede neurodegeneration. We have found that polyQ Atro downregulates fat, which protects from neurodegeneration and Atrophin toxicity trhough the Hippo kinase cascade.
2011-03-01 | GSE26246 | GEO
Project description:Spinocerebellar ataxia type 7 (SCA7) belonging to a family of autosomal dominant cerebellar ataxias (ADCAs) is pathomechanistically associated with the group of polyglutamine expansion disorders which include SCA 1-3, 6, 7 and 17, and Huntington’s disease. These rare diseases share a common mutational feature that is the expansion of CAG repeat sequence in disease causing genes. These mutations lead to neuronal accumulation of expanded polyglutamine proteins and selective patterns of neurodegeneration. SCA7 is caused by a polyglutamine expansion in ATAXIN-7 (ATXN7), a subcomponent of co-activatory transcriptional complex SAGA and primarily affects the cerebellum, retina and brainstem. Currently, only treatments alleviating symptoms are available to patients. Allele-selective lowering of mutant polyQ proteins promises to have high therapeutic outcomes and safety profiles. In this study, PhP.eB adeno-associated virus (AAV PhP.eB) was used to deliver several shRNAs targeting expanded CAG repeats that were tested for their safety and efficacy to lower the mATXN7 level in the brain. The SCA7140Q/5Q knock-in mice that expresses a mutated Atxn7 allele harboring an expansion of 140 CAG triplet repeats and the wild type mouse allele with 5 CAGs were used in the study. Our SCA7 140Q/5Q KI mouse model remarkably recapitulates cardinal features of SCA7 and bears the potential for pre-clinical trials (Niewiadomska-Cimicka et al., J.Neurosci., 2021). We showed that systemic injection of the AAV-shA4, the most allele-selective and safe reagent of our collection, results in improvement of motor phenotypes as indicated in open field test, and partial correction of transcriptional alterations in the cerebellum of SCA7 mice.
2024-05-14 | GSE244970 | GEO
Project description:Spinocerebellar Ataxia Type 7 (SCA7) belonging to ADCAs is pathomechanistically related to a group of polyglutamine expansion disorders. SCA7 affects primarily brainstem, retina and cerebellum. The distinctive feature of SCA7 among ADCAs is a progressive visual impairment due to a cone-rod photoreceptor dystrophy. Ultrastructural analysis of SCA7 mouse models revealed that photoreceptors progressively lose their outer segments, a structure essential for phototransduction, which requires daily renewal. The lack of outer segment renewal correlates with decreased expression of photoreceptor-specific genes, suggesting that progressive breakdown of photoreceptor cell identity accounts for SCA7 retinopathy. SCA7 is due to a polyglutamine expansion in ATXN7, a component of the multiprotein SPT-ADA-GCN5 Acetyltransferase (SAGA) complex, a highly conserved coactivator of transcription. SAGA harbors two chromatin remodeling activities: acetylation and deubiquitynation of histones crucial for transcription initiation and elongation. The role of SAGA in SCA7 pathogenesis and the tissue specific genetic breakdown remains to be elucidated. We addressed this issue using our new SCA7 knock-in mouse model (SCA7140Q/140Q), which recapitulates cardinal features of SCA7. Using ChIP-seq approach, we confirmed the general decrease of H3K9ac in most gene promoters in SCA7 retina, which alone cannot explain the specific gene deregulation. Interestingly, we discovered that photoreceptor identity genes, which are strongly downregulated in SCA7, harbor an unusual broad profile of H3K9ac that encompasses the entire gene. We further show that H3K9ac broad profiles at photoreceptor gene loci coincide with the presence of a broad H3K27ac, a signature of superenhancers. Furthermore, using vicinity criteria we identified enhancer RNAs (eRNAs), annotated to the photoreceptor identity genes possessing an atypical H3K9ac/H3K27ac enhancer signature. Finally, we found a synchronized expression of eRNAs and photoreceptor identity genes during retinal development, suggesting a regulatory role of these eRNAs. The decreased eRNA levels on hypoacetylated loci in the retina correlate with the downregulation of photoreceptor identity genes in symptomatic but not in pre-symptomatic SCA7 mice. Our results support the view that epigenetic and enhancer alterations compromise the maintenance of neuronal identity in SCA7.
2022-12-20 | GSE181323 | GEO
Project description:Spinocerebellar Ataxia Type 7 (SCA7) belonging to ADCAs is pathomechanistically related to a group of polyglutamine expansion disorders. SCA7 affects primarily brainstem, retina and cerebellum. The distinctive feature of SCA7 among ADCAs is a progressive visual impairment due to a cone-rod photoreceptor dystrophy. Ultrastructural analysis of SCA7 mouse models revealed that photoreceptors progressively lose their outer segments, a structure essential for phototransduction, which requires daily renewal. The lack of outer segment renewal correlates with decreased expression of photoreceptor-specific genes, suggesting that progressive breakdown of photoreceptor cell identity accounts for SCA7 retinopathy. SCA7 is due to a polyglutamine expansion in ATXN7, a component of the multiprotein SPT-ADA-GCN5 Acetyltransferase (SAGA) complex, a highly conserved coactivator of transcription. SAGA harbors two chromatin remodeling activities: acetylation and deubiquitynation of histones crucial for transcription initiation and elongation. The role of SAGA in SCA7 pathogenesis and the tissue specific genetic breakdown remains to be elucidated. We addressed this issue using our new SCA7 knock-in mouse model (SCA7140Q/140Q), which recapitulates cardinal features of SCA7. Using ChIP-seq approach, we confirmed the general decrease of H3K9ac in most gene promoters in SCA7 retina, which alone cannot explain the specific gene deregulation. Interestingly, we discovered that photoreceptor identity genes, which are strongly downregulated in SCA7, harbor an unusual broad profile of H3K9ac that encompasses the entire gene. We further show that H3K9ac broad profiles at photoreceptor gene loci coincide with the presence of a broad H3K27ac, a signature of superenhancers. Furthermore, using vicinity criteria we identified enhancer RNAs (eRNAs), annotated to the photoreceptor identity genes possessing an atypical H3K9ac/H3K27ac enhancer signature. Finally, we found a synchronized expression of eRNAs and photoreceptor identity genes during retinal development, suggesting a regulatory role of these eRNAs. The decreased eRNA levels on hypoacetylated loci in the retina correlate with the downregulation of photoreceptor identity genes in symptomatic but not in pre-symptomatic SCA7 mice.
2022-12-20 | GSE181324 | GEO
Project description:Dentatorubral-pallidoluysian Atrophy (DRPLA) is a human polyQ disease caused by the expansion of a CAG strech in the atrophin-1 (at-1) gene. In all vertebrates, a second atrophin gene (at-2) is present and it encodes a related protein void of polyQ tracks. In D.melanogaster there is one conserved Atrophin (Atro) gene, ubiquitously expressed, which contains all functional domains of vertebrate Atrophins, including two polyQ stretches. To understand to what extent transcriptional alterations cause neurodegeneration and are linked to the normal functions of Atrophin, we performed a genome wide transcriptional profiling in our Drosophila models, focusing on primary events that precede neurodegeneration. We have found that polyQ Atro downregulates fat, which protects from neurodegeneration and Atrophin toxicity trhough the Hippo kinase cascade. Neurodegeneration progression caused by poly glutamine expansions of the Atro gene is measured by mRNA expression profiles in 4 D.melanogaster genotypes: in wild-type animals (controls), animals constitutively expressing the wild-type Atro transgene, animals constitutively expressing the polyQ expanded Atro transgenes A66QC and A75QN. The expressions of the Atro genes are under a GMR-Gal4 driver repressed by a Gal80 universal repressor sensitive to temperature. When flies are raised at 18 C, the transgenes are not expressed, but their expression is switched on when they are shifted to the ageing protocol at 29 C at time point day 0. The neurodegeneration is assessed after 2 and 14 days post-high-temperature shift.
2011-03-01 | E-GEOD-26246 | biostudies-arrayexpress