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Expression of human C9ORF72 hexanucleotide expansion reproduces RNA foci and dipeptide repeat proteins but not neurodegeneration in BAC transgenic mice

ABSTRACT: Nuclear RNA foci are often associated with mis-regulation of RNA processing in repeat expansion diseases. Here we report transcriptomic analysis of mice expressing expanded G4C2 repeats, the most common genetic cause of FTD/ALS. We show that the presence of numerous nuclear G4C2 repeat RNA foci does not cause extensive changes in RNA processing in this model organism.

ORGANISM(S): Mus musculus

PROVIDER: GSE74973 | GEO | 2015/11/14

SECONDARY ACCESSION(S): PRJNA302110

REPOSITORIES: GEO

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Differential Toxicity of Nuclear RNA Foci Versus Dipeptide Repeat Proteins in a Drosophila Model of C9ORF72 FTD/ALS

Project description:Nuclear RNA foci are often associated with mis-regulation of RNA processing in repeat expansion diseases. Here we report transcriptomic analysis of flies carrying expanded G4C2 repeats, the most common genetic cause of FTD/ALS. By obtaining an average of 32 million reads per library, we show that the presence of numerous nuclear G4C2 repeat RNA foci does not cause extensive changes in RNA processing in this model organism. Comparision of the transcriptomic profile of flies expressing 5R or 160R from two different chromosomes

2015-09-11 | E-GEOD-72771 | biostudies-arrayexpress

Differential Toxicity of Nuclear RNA Foci Versus Dipeptide Repeat Proteins in a Drosophila Model of C9ORF72 FTD/ALS

2015-09-11 | GSE72771 | GEO

Human C9ORF72 Hexanucleotide Expansion Reproduces RNA Foci and Dipeptide Repeat Proteins but Not Neurodegeneration in BAC Transgenic Mice.

Project description:A non-coding hexanucleotide repeat expansion in the C9ORF72 gene is the most common mutation associated with familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). To investigate the pathological role of C9ORF72 in these diseases, we generated a line of mice carrying a bacterial artificial chromosome containing exons 1 to 6 of the human C9ORF72 gene with approximately 500 repeats of the GGGGCC motif. The mice showed no overt behavioral phenotype but recapitulated distinctive histopathological features of C9ORF72 ALS/FTD, including sense and antisense intranuclear RNA foci and poly(glycine-proline) dipeptide repeat proteins. Finally, using an artificial microRNA that targets human C9ORF72 in cultures of primary cortical neurons from the C9BAC mice, we have attenuated expression of the C9BAC transgene and the poly(GP) dipeptides. The C9ORF72 BAC transgenic mice will be a valuable tool in the study of ALS/FTD pathobiology and therapy.

| S-EPMC4828340 | biostudies-literature

Enhanced insulin signalling ameliorates C9orf72 hexanucleotide repeat expansion toxicity in Drosophila

Project description:G4C2 repeat expansions within the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The repeats undergo repeat-associated non-ATG translation to generate toxic dipeptide repeat proteins. Here, we show that insulin/Igf signalling is reduced in fly models of C9orf72 repeat expansion using RNA-sequencing of adult brain. We further demonstrate that activation of insulin/Igf signalling can mitigate multiple neurodegenerative phenotypes in flies expressing either expanded G4C2 repeats or the toxic dipeptide repeat protein poly-GR. Levels of poly-GR are reduced when components of the insulin/Igf signalling pathway are genetically activated in the diseased flies, suggesting a mechanism of rescue. Modulating insulin signalling in mammalian cells also lowers poly-GR levels. Remarkably, systemic injection of insulin improves the survival of flies expressing G4C2 repeats. Overall, our data suggest that modulation of insulin/Igf signalling could be an effective therapeutic approach against C9orf72 ALS/FTD.

2021-03-20 | GSE151826 | GEO

C9orf72 BAC Transgenic Mice Display Typical Pathologic Features of ALS/FTD

Project description:Noncoding expansions of a hexanucleotide repeat (GGGGCC) in the C9orf72 gene are the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia. Here we report transgenic mice carrying a bacterial artificial chromosome (BAC) containing the full human C9orf72 gene with either a normal allele (15 repeats) or disease-associated expansion (~100–1,000 repeats; C9-BACexp). C9-BACexp mice displayed pathologic features seen in C9orf72 expansion patients, including widespread RNA foci and repeat-associated non-ATG (RAN) translated dipeptides, which were suppressed by antisense oligonucleotides targeting human C9orf72. Nucleolin distribution was altered, supporting that either C9orf72 transcripts or RAN dipeptides promote nucleolar dysfunction. Despite early and widespread production of RNA foci and RAN dipeptides in C9-BACexp mice, behavioral abnormalities and neurodegeneration were not observed even at advanced ages, supporting the hypothesis that RNA foci and RAN dipeptides occur presymptomatically and are not sufficient to drive neurodegeneration in mice at levels seen in patients.

2016-02-10 | GSE77720 | GEO

C9orf72 BAC Transgenic Mice Display Typical Pathologic Features of ALS/FTD

Project description:Noncoding expansions of a hexanucleotide repeat (GGGGCC) in the C9orf72 gene are the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia. Here we report transgenic mice carrying a bacterial artificial chromosome (BAC) containing the full human C9orf72 gene with either a normal allele (15 repeats) or disease-associated expansion (~100â??1,000 repeats; C9-BACexp). C9-BACexp mice displayed pathologic features seen in C9orf72 expansion patients, including widespread RNA foci and repeat-associated non-ATG (RAN) translated dipeptides, which were suppressed by antisense oligonucleotides targeting human C9orf72. Nucleolin distribution was altered, supporting that either C9orf72 transcripts or RAN dipeptides promote nucleolar dysfunction. Despite early and widespread production of RNA foci and RAN dipeptides in C9-BACexp mice, behavioral abnormalities and neurodegeneration were not observed even at advanced ages, supporting the hypothesis that RNA foci and RAN dipeptides occur presymptomatically and are not sufficient to drive neurodegeneration in mice at levels seen in patients. To compare the RNA Seq profiles from the cortex and spinal cord of transgenic mice expressing unexpanded human C9orf72 (F08, n=4), expanded human C9orf72 (F112, n=3/4), and nontransgenic controls (n=4).

2016-02-10 | E-GEOD-77720 | biostudies-arrayexpress

Identification of proteins interacting with GFP-GA, GR, PA, PG and PR fusion proteins

Project description:Expansion of a hexanucleotide repeat GGGGCC (G4C2) in C9ORF72 is the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia. Transcripts carrying (G4C2) expansions undergo unconventional, non-ATG-dependent translation, generating toxic dipeptide repeat (DPR) proteins that are thought to contribute to disease. Here, we transfected HEK 293T cells with GFP-tagged dipeptides (GA, GR, PA, PG and PR) and performed LC-MS/MS to identify immunoprecipitated interactors.

2016-10-03 | PXD004938 | Pride

Gene expression signatures for Normal-looking, fibrotic foci and hyperplastic (adjacent to fibrotic foci) area in IPF lungs

Project description:To further understand the pathologic microenvironment in IPF, we have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to distinguish normal and IPF lung in normal-looking, fibrotic foci and hyperplastic areas of IPF lung. Four IPF lungs were dissected into normal-looking, fibrotic foci and hyperplastic areas by Laser-Capture-Microdissection. Gene expression analysis showed that 638 significantly different genes were identified that clearly distinguished the different IPF microenvironments . Among them, MMP19 was revealed as one of the most significantly up-regulated genes that distinguished normal looking epithelial cells (N) to hyperplastic epithelial cells, MMP19 up-regulation in IPF lungs was verified by immunohistochemical (IHC), qRT-PCR and Western-blot. IPF lungs are heterogeneity complex, which comprise normal looking area, fibrotic foci and hyperplastic area. In this study we separated the normal, fibrotic foci and hyperplastic area by LCM and employed Agilent whole genome gene expression microarray profiling to identify genes with the potential to distinguish the unique microenironment of IPF

2013-01-11 | E-GEOD-35309 | biostudies-arrayexpress

Correction of ALS-related phenotypes in iPSC-derived motor neurons carrying a hexanucleotide expansion mutation in C9orf72 by CRISPR/Cas9 genome editing and homology-directed repair

Project description:The G4C2 hexanucleotide repeat expansion (HRE) in C9orf72 is the commonest cause of familial amyotrophic lateral sclerosis (ALS). A number of different methods have been used in an attempt to generate isogenic control lines using CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 and NHEJ by deleting the repeat region without replacing it with the normal repeat size, but typically this strategy carries the risk of creating indels and genomic instability. In this study we demonstrate complete correction of an induced pluripotent stem cell (iPSC) line derived from a C9orf72-HR positive ALS patient using CRISPR/Cas9 genome editing and homology directed repair (HDR), resulting in replacement of the excised region with a donor template carrying the wild-type repeat size to maintain the genetic architecture of the locus. The isogenic correction of the C9orf72 HRE restored normal expression and methylation at the C9orf72 locus, reduced intron retention in the edited lines, and abolished pathological phenotypes associated with the C9orf72 HRE expansion in iPSC derived motor neurons (iPSMNs). RNA sequencing of the mutant line identified 2220 differentially expressed genes compared to its isogenic control. Enrichment analysis demonstrated an over-representation of ALS relevant pathways in the presence of the C9orf72 HRE, including calcium ion dependent exocytosis, synaptic transport and the KEGG ALS pathway, as well as new targets of potential relevance to ALS pathophysiology.Complete correction of the C9orf72 HRE in iPS MNs by CRISPR/Cas9 mediated HDR provides an ideal model to study the earliest effects of the hexanucleotide expansion on cellular homeostasis and the key pathways implicated in ALS pathophysiology.

2020-05-19 | GSE139144 | GEO

C9ORF72 GGGGCC expanded repeats produce splicing dysregulation which correlates with disease severity in amyotrophic lateral sclerosis [HG-U133_Plus_2]

Project description:Objective: An intronic GGGGCC-repeat expansion of C9ORF72 is the most common genetic variant of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. The mechanism of neurodegeneration is unknown, but a direct effect on RNA processing mediated by RNA foci transcribed from the repeat sequence has been proposed. Results: Gene level analysis revealed a number of differentially expressed networks and both cell types exhibited dysregulation of a network functionally enriched for genes encoding ‘RNA splicing’ proteins. There was a significant overlap of these genes with an independently generated list of GGGGCC-repeat protein binding partners. At the exon level, in lymphoblastoid cells derived from C9ORF72-ALS patients splicing consistency was lower than in lines derived from non-C9ORF72 ALS patients or controls; furthermore splicing consistency was lower in samples derived from patients with faster disease progression. Frequency of sense RNA foci showed a trend towards being higher in lymphoblastoid cells derived from patients with shorter survival, but there was no detectable correlation between disease severity and DNA expansion length. Significance: Up-regulation of genes encoding predicted binding partners of the C9ORF72 expansion is consistent with an attempted compensation for sequestration of these proteins. A number of studies have analysed changes in the transcriptome caused by C9ORF72 expansion, but to date findings have been inconsistent. As a potential explanation we suggest that dynamic sequestration of RNA processing proteins by RNA foci might lead to a loss of splicing consistency; indeed in our samples measurement of splicing consistency correlates with disease severity. Gene expression profiling utilised total RNA extracted from motor neurons derived from human ALS patients with an expansion of C9ORF72 (n=8), and controls (n=3).

2015-05-08 | E-GEOD-68605 | biostudies-arrayexpress

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