Characterization of C9orf72 haplotypes to evaluate the effects of normal and pathological variations on its expression and splicing
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ABSTRACT:
PROVIDER: PRJNA683890 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR13232356.fastq.gz | Fastqsanger.gz | |||
| SRR13232357.fastq.gz | Fastqsanger.gz | |||
| SRR13232358.fastq.gz | Fastqsanger.gz | |||
| SRR13232359.fastq.gz | Fastqsanger.gz | |||
| SRR13232360.fastq.gz | Fastqsanger.gz |
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Project description:Expansion of the hexanucleotide repeat (HR) in the first intron of the chromosome 9 open reading frame 72 (C9orf72) gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in Caucasians. All C9orf72 ALS/FTD patients share a common risk (R) haplotype, but its single nucleotide polymorphism (SNP) signature has not been fully characterized. Here, we characterized the C9orf72 haplotypes in Europeans and created a detailed molecular map, including HR length, for each haplotype. By analyzing RNA-seq reads and sequencing chromatograms that overlap with heterozygous SNP sites, we identified allelic differences in C9orf72 expression in normal subjects and ALS patients. In cells from healthy individuals, upstream promoter transcript levels increased with increased HR length. Intron 1 levels were higher in one of the non-R haplotypes due to SNP variation, and in R haplotype with 10 or more HR units. In pathological HR expansion, we observed the highest levels of intron 1 that were accompanied by aberrantly spliced transcripts at cryptic donor sites downstream of the expanded HR. Intron 1 retention was associated with sequential intron 2 retention. The SNP signature of C9orf72 haplotypes described here enables allele-specific analysis of transcriptional products and may pave the way to allele-specific therapeutic strategies.
2021-03-01 | GSE162943 | GEO
Project description:To differentiate, characterize and examine intrinsic phenotypes of C9orf72 ALS/FTD patient-derived induced pluripotent stem cells into microglia (iPSC-MG). Moderate molecular and functional differences were observed in C9orf72 iPSC-MG mono-cultures despite the presence of C9orf72 pathological features.
2023-05-23 | GSE233262 | GEO
Project description:Expansion of the hexanucleotide repeat (HR) in the first intron of the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in Caucasians. All C9orf72-ALS/FTD patients share a common risk (R) haplotype. To study C9orf72 expression and splicing from the mutant R allele compared to the complementary normal allele in ALS/FTD patients, we initially created a detailed molecular map of the single nucleotide polymorphism (SNP) signature and the HR length of the various C9orf72 haplotypes in Caucasians. We leveraged this map to determine the allelic origin of transcripts per patient, and decipher the effects of pathological and normal HR lengths on C9orf72 expression and splicing. In C9orf72 ALS patients' cells, the HR expanded allele, compared to non-R allele, was associated with decreased levels of a downstream initiated transcript variant and increased levels of transcripts initiated upstream of the HR. HR expanded R alleles correlated with high levels of unspliced intron 1 and activation of cryptic donor splice sites along intron 1. Retention of intron 1 was associated with sequential intron 2 retention. The SNP signature of C9orf72 haplotypes described here enables allele-specific analysis of transcriptional products and may pave the way to allele-specific therapeutic strategies.
| S-EPMC8031855 | biostudies-literature
Project description:Moderate intrinsic phenotypic alterations in C9orf72 ALS/FTD iPSC-microglia despite the presence of C9orf72 pathological features
| PRJNA975583 | ENA
Project description:Purpose: The purpose of this experiment is to identify a C9-ALS/FTD specific genomic profile in fibroblast lines that is distinct from sporadic ALS without C9orf72 expansion and non-neurologic control cells. The study will then evaluate the effect on this identified profile of ASO treatment targeting the sense strand RNA transcript of the C9orf72 gene. Methods: Expression profiling was performed on RNAs from fibroblasts of four C9orf72 patients, four control individuals and four sporadic ALS patients using Multiplex Analysis of PolyA-linked Sequences method. Results: Hierarchical clustering of expression values for all genes showed that the four C9orf72 patient lines had an expression profile distinct from control and sporadic ALS lines. Statistical comparison of expression values between the four C9orf72 lines and the four control lines revealed that 122 genes were upregulated (defined by a False Discovery Rate FDR<0.05) and 34 genes were downregulated (defined by a False Discovery Rate FDR <0.05) in C9orf72 patient fibroblasts. Conclusions: A genome wide RNA signature can be defined in fibroblasts with C9orf72 expansion. ASO-mediated reduction of C9orf72 RNA levels in fibroblasts with the hexanucleotide expansion efficiently reduced accumulation of GGGGCC RNA foci. This did not, however, generate a reversal of the C9orf72 RNA profile. Use of Multiplex Analysis of PolyA-linked Sequences to identify expression changes in fibroblasts from amyotrophic lateral sclerosis and frontotemporal dementia patients harboring an hexanucleotide expansion in the C9orf72 gene.
2013-11-12 | E-GEOD-51684 | biostudies-arrayexpress
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: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
Project description:RNA sequencing analysis of human iPSC-derived neural stem cells generated from Control, C9ORF72 FTD/ALS, an isogenic control, and a C9ORF72 knockout line. The goal of this study is to determine the effects of the C9ORF72 repeat expansion on neural stem cell proliferation and differentiation.
2023-08-12 | GSE238005 | GEO
Project description:The hyper-unstable Chr9p21 locus, harbouring the interferon gene cluster, oncogenes and C9orf72, is linked to multiple diseases. C9orf72 (GGGGCC)n expansions (C9orf72Exp) are associated with incompletely penetrant amyotrophic lateral sclerosis, frontotemporal dementia and autoimmune disorders. C9orf72Exp patients display hyperactive cGAS-STING-linked interferon immune and DNA damage responses, but the source of immuno-stimulatory or damaged DNA is unknown. Here, we show C9orf72Exp in pre-symptomatic and ALS-FTD patient cells and brains cause the folate-sensitive chromosomal fragile site, FRA9A. FRA9A centers on > 33kb of C9orf72 as highly-compacted chromatin embedded in an 8.2Mb fragility zone spanning 9p21, encompassing 46 genes, making FRA9A one of the largest fragile sites. C9orf72Exp cells show chromosomal instability, heightened global- and Chr9p-enriched sister-chromatid exchanges, truncated-Chr9s, acentric-Chr9s and Chr9-containing micronuclei, providing endogenous sources of damaged and immunostimulatory DNA. Cells from one C9orf72Exp patient contained highly-rearranged FRA9A-expressing Chr9 with Chr9-wide dysregulated gene expression. Somatic C9orf72Exp repeat instability and chromosomal fragility are sensitive to folate-deficiency. Age-dependent repeat instability, chromosomal fragility, and chromosomal instability can be transferred to CNS and peripheral tissues of transgenic C9orf72Exp mice, implicating C9orf72Exp as the source. Our results highlight unappreciated effects of C9orf72 expansions that trigger vitamin-sensitive chromosome fragility, adding structural variations to the disease-enriched 9p21 locus, and likely elsewhere.
2024-11-26 | GSE262674 | GEO
Project description:Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Decreased expression of C9orf72 is seen in expansion carriers, suggesting loss of function may play a role in disease. We find that two independent mouse lines lacking the C9orf72 ortholog (3110043O21Rik) in all tissues developed normally and aged without motor neuron disease. Instead, C9orf72 null mice developed progressive splenomegaly and lymphadenopathy with accumulation of engorged macrophage-like cells. C9orf72 expression was highest in myeloid cells, and loss of C9orf72 led to lysosomal accumulation and altered immune responses in macrophages and microglia, with age-related neuroinflammation similar to C9orf72 ALS but not sporadic ALS patient tissue. Thus, C9orf72 is required for normal function of myeloid cells, and altered microglial function may contribute to neurodegeneration in C9orf72 expansion carriers.
2016-03-24 | GSE77681 | GEO