Homo sapiens
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA128015 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:The inherited neurodegenerative disease Friedreich’s ataxia (FRDA) is caused by hyperexpansion of GAA•TTC trinucleotide repeats within the first intron of the FXN gene, encoding the mitochondrial protein frataxin. Long GAA•TTC repeats causes heterochromatin-mediated silencing and loss of frataxin in affected individuals. We report the derivation of induced pluripotent stem cells (iPSCs) from FRDA patient fibroblasts through retroviral transduction of transcription factors. FXN gene repression is maintained in the iPSCs, as are the mRNA and miRNA global expression signatures reflecting the human disease. GAA•TTC repeats uniquely in FXN in the iPSCs exhibit repeat instability similar to patient families, where they expand and/or contract with discrete changes in length between generations. The mismatch repair enzyme Msh2, implicated in repeat instability in other triplet repeat diseases, is highly expressed in the iPSCs, occupies FXN intron 1, and shRNA silencing of Msh2 impedes repeat expansion, providing a possible molecular explanation for repeat expansion in FRDA.
2010-07-02 | GSE22651 | GEO
Project description:The inherited neurodegenerative disease Friedreichâ??s ataxia (FRDA) is caused by hyperexpansion of GAAâ?¢TTC trinucleotide repeats within the first intron of the FXN gene, encoding the mitochondrial protein frataxin. Long GAAâ?¢TTC repeats causes heterochromatin-mediated silencing and loss of frataxin in affected individuals. We report the derivation of induced pluripotent stem cells (iPSCs) from FRDA patient fibroblasts through retroviral transduction of transcription factors. FXN gene repression is maintained in the iPSCs, as are the mRNA and miRNA global expression signatures reflecting the human disease. GAAâ?¢TTC repeats uniquely in FXN in the iPSCs exhibit repeat instability similar to patient families, where they expand and/or contract with discrete changes in length between generations. The mismatch repair enzyme Msh2, implicated in repeat instability in other triplet repeat diseases, is highly expressed in the iPSCs, occupies FXN intron 1, and shRNA silencing of Msh2 impedes repeat expansion, providing a possible molecular explanation for repeat expansion in FRDA. 65 samples from various number of tissue, primary cell lines undifferenatiated human embryonic stem cell lines, induces pluripotent stem cell lines have been run on Illumina HT12 v3 chips.
2010-07-30 | E-GEOD-22651 | biostudies-arrayexpress
Project description:Lymphoblast cells from a patient with Freidriech's Ataxia were incubated with pyrrole-imidazole polyamides targeted to the GAA triplet repeat in the intron 1. The polyamides were shown in cell culture to increase levels of endogenous frataxin mRNA. A normal sibling derived lymphoblast cell line was used as a control. Keywords: human lymphoblast cells
2006-06-14 | GSE5040 | GEO
Project description:Lymphoblast cells from a patient with Freidriech's Ataxia were incubated with pyrrole-imidazole polyamides targeted to the GAA triplet repeat in the intron 1. The polyamides were shown in cell culture to increase levels of endogenous frataxin mRNA. A normal sibling derived lymphoblast cell line was used as a control. Experiment Overall Design: Normal (GM15851) and patient (GM15850) cell lines were incubated in the presence of match polyamide FA1 at 1uM, 2uM or mismatch polyamide FA2 at 2uM for 7days prior to RNA purification and microarray analysis.
2008-06-13 | E-GEOD-5040 | biostudies-arrayexpress
Project description:Transcriptional down regulation caused by intronic triplet repeat expansions underlies diseases such as Friedreich?s ataxia. This down regulation of gene expression is coupled with epigenetic changes but the underlying mechanisms are unknown. Here, we show that an intronic TTC/GAA triplet expansion within the IIL1 gene of Arabidopsis thaliana results in accumulation of 24-nt siRNAs and repressive histone marks at the IIL1 locus, which in turn causes its transcriptional down regulation and an associated phenotype. Knocking down DICER LIKE-3 (DCL3), which produces 24-nt siRNAs, suppressed transcriptional down regulation of IIL1 and the expansion-associated phenotype. Furthermore, knocking down additional components of the RNA-dependent DNA Methylation (RdDM) pathway, also suppressed both transcriptional down regulation of IIL1 and the repeat expansion associated phenotype. Thus our results show that triplet repeat expansions can lead to local siRNA biogenesis, which in turn down regulates transcription through an RdDM-dependent epigenetic modification.
2018-07-25 | GSE113923 | GEO
Project description:Expansion of triplex-forming GAA/TTC repeats in the first intron of FRDA gene is known to cause Friedreich’s ataxia. Besides FRDA, there are a number of other highly polymorphic GAA/TTC loci in the human genome where the size variations so far were considered to be a neutral event. Using yeast as a model system, we demonstrate that expanded GAA/TTC repeats represent a threat to eukaryotic genome integrity by triggering double-strand breaks and gross chromosomal rearrangements. The fragility potential strongly depends on the length of the track and orientation of the repeats relative to the replication origin which correlates with their propensity to adopt secondary structure and to block replication progression. We show that fragility is mediated by mismatch repair machinery and requires the MutS(beta) and endonuclease activity of MutL(alpha). We suggest that the mechanism of GAA/TTC-induced chromosome aberrations defined in yeast can also operate in human carriers with expanded tracks. Keywords: CGH-array Genomic DNA from each of 15 strains was competitively hybridized to DNA from the parent diploid strain (Cy3/green). Gains of genomic segments in the survivors were detected as continuous regions of positive Log2 Red:Green ratios, while losses were detected as negative Log2 Red:Green ratios.
2008-05-14 | E-GEOD-11425 | biostudies-arrayexpress
Project description:Expansion of triplex-forming GAA/TTC repeats in the first intron of FRDA gene is known to cause Friedreich’s ataxia. Besides FRDA, there are a number of other highly polymorphic GAA/TTC loci in the human genome where the size variations so far were considered to be a neutral event. Using yeast as a model system, we demonstrate that expanded GAA/TTC repeats represent a threat to eukaryotic genome integrity by triggering double-strand breaks and gross chromosomal rearrangements. The fragility potential strongly depends on the length of the track and orientation of the repeats relative to the replication origin which correlates with their propensity to adopt secondary structure and to block replication progression. We show that fragility is mediated by mismatch repair machinery and requires the MutS(beta) and endonuclease activity of MutL(alpha). We suggest that the mechanism of GAA/TTC-induced chromosome aberrations defined in yeast can also operate in human carriers with expanded tracks. Keywords: CGH-array
2008-05-14 | GSE11425 | GEO
Project description:Disease-specific induced pluripotent stem (iPS) cells have been used for a model to analyze pathogenesis of the disease. In this study, we generated iPS cells derived from a fibroblastic cell line of ataxia telangiectasia (AT-iPS cells), a neurodegenerative, inherited disease with chromosomal instability and hypersensitivity to ionizing radiation. AT-iPS cells exhibited hypersensitivity to X-ray irradiation, one of the characteristics of the disease. Surprisingly, while parental ataxia telangiectasia cells exhibited significant chromosomal abnormalities, AT-iPS cells did not show any chromosomal instability in vitro, i.e. maintenance of intact chromosomes at least by 80 passages (560 days) probably due to robust stability of pluripotent stem cells such as iPS cells and embryonic stem cells. The whole exome analysis also showed comparable nucleotide substitution speed in AT-iPS cells. Interestingly, after longer period of AT-iPS implantation into immunodeficient mice, teratoma generated by AT-iPS cells exhibited telangiectasia and carcinogenesis that are two characteristic symptoms of ataxia telangiectasia. Taken together, AT-iPS cells would be a good model for ataxia telangiectasia to clarify pathogenesis of the disease, and may allow us to facilitate development of drugs that inhibit ataxia and hypersensitivity to ionizing radiation for therapeutic application. The parental AT1OS fibroblast cells and four independent AT-iPS clones were subjected to Illumina HumanCytoSNP-12 v2.1 BeadChip analysis.
2013-06-22 | E-GEOD-47498 | biostudies-arrayexpress
Project description:In an 8-year-old girl of consanguineous Turkish parents, who developed ataxic gait and polyneuropathy at the age of 3 years, we identified a biallelic missense variant c.424C>T, p.R142W in Glypican 1 (GPC1) by using whole genome sequencing. Up to date, GPC1 has not been associated with a neuromuscular disorder and we hypothesized that this variant, which is predicted as deleterious (CADD score 26.4) may be causative for the disease. Using mass spectrometry-based proteomics, we investigated the interactome of the GPC1 missense variant. We identified 198 proteins interacting with GPC1, of which 16 were altered due to the missense variant. Differentially regulated proteins include members of the vacuolar ATPase (v-ATPase) and mammalian target of rapamycin complex 1 (mTORC1) complexes, whose mis-regulation could have a potential impact on disease severity in the patient. Importantly, these proteins are novel interaction partners of GPC1. At 11 years of age, the patient developed a cardiomyopathy and kyphoscoliosis and a Friedreich’s Ataxia (FRDA) was suspected. Indeed a 104 GAA-repeat expansion in the FXN gene was found. Given the unusually severe phenotype in a patient with FRDA carrying only 104 GAA-repeats, we currently assume that the disturbed function in GPC1 may exacerbate the disease phenotype.
2023-08-15 | PXD040023 | Pride
Project description:Friedreich ataxia (FRDA) is a recessive neurodegenerative disease characterized by progressive ataxia, dyscoordination, and loss of vision. The variable length of the pathogenic GAA triplet repeat expansion in the FXN gene in part explains Inter-individual variability in severity of disease. The GAA repeat expansion leads to epigenetic silencing of FXN; therefore, variability in properties of epigenetic effector proteins could also regulate the severity of FRDA. In an exploratory analysis, DNA from 88 FRDA patients was analyzed to determine if any of 5 non-synonymous SNPs in HDACs/ SIRTs predicted FRDA disease severity. Results suggested the need for a full analysis (569 FRDA patients) at the rs352493 locus in SIRT6 (S46N SNP). Disease features were compared between patients with the common N46 SIRT6 variant and the less common S46 variant. Biochemical properties of SIRT6 were compared between S46 and N46. Linear regression of the exploratory cohort suggested a SNP (rs352493) in SIRT6 predicted neurologic severity. In follow up analysis, the genotype of SIRT6 at the locus rs352493 predicted disease features of FRDA. Patients with the S46 SIRT6 variant performed better on measures of neurological and visual function over time when compared to the more common N46 SIRT6 variant. S46 SIRT6 did not alter expression or enzymatic activity of SIRT6 or FXN however, S46 patients showed whole transcriptome differences compared to N46 patients, indicative of compensatory mechanisms against whole transcriptome changes seen in FRDA.
2022-10-04 | GSE200907 | GEO