Correction of splicing defect in compound heterozygous FRDA patient carrying FXN 165+5G>C point mutation.
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PROVIDER: PRJNA1093135 | ENA |
REPOSITORIES: ENA
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Project description:Friedreich’s ataxia is an autosomal recessive disease caused by mutations in the FXN gene. Approximately 95% of patients harbor homozygous GAA repeat expansion in the intron 1 of the FXN, while the remaining 5% are compound heterozygotes carrying GA expansion on 1 allele and point mutation on the other allele. Here, we characterized a G to C transversion in position 5 of the intron 1 of the FXN. Mutation results in profound downregulation of FXN mRNA and protein levels. Transcriptome and RT-PCR analyses demonstrated aberrant splicing of the FXN gene caused by this mutation that can be at least in part corrected with antisense oligonucleotides (ASOs) targeting intron 1.
2025-07-10 | GSE262763 | GEO
Project description:Accumulating data from different groups have demonstrated that alteration of post-translational histone modifications is an important underlying mechanism for FXN silencing in FRDA. The relationship between chromatin architecture and histone modification marks in the FXN gene locus is likely to be important for understanding the silencing mechanism. We therefore investigated the spatial organization of the FXN gene locus using the 3C-sequencing method. EBV transformed lymphoblastoid cell lines derived from patients (GM15850, GM16234 and GM16798) and Healthy control (GM14664 and GM15851) were used for generating 3C-seq libraries.
2013-12-16 | E-GEOD-42961 | biostudies-arrayexpress
Project description:Accumulating data from different groups have demonstrated that alteration of post-translational histone modifications is an important underlying mechanism for FXN silencing in FRDA. The relationship between chromatin architecture and histone modification marks in the FXN gene locus is likely to be important for understanding the silencing mechanism. We therefore investigated the spatial organization of the FXN gene locus using the 3C-sequencing method.
2013-12-16 | GSE42961 | GEO
Project description:Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by mutations in the frataxin (FXN) gene. In this study, we immortalized mouse embryonic fibroblasts (MEFs) derived from G127V Fxn mutant mice and compared them to the wild-type (WT) MEFs. Mutant G127V MEFs demonstrated decreased cell proliferation and ATP production, as well as an increase in reactive oxygen species (ROS) production when compared to WT cells. These phenotypes are partially corrected by exogenous expression of frataxin. Surprisingly, extended passaging of immortalized G127V Fxn MEFs improves their proliferation, and alleviates ATP deficiency as well as decreases ROS levels despite persistent frataxin deficiency. We defined gene expression changes associated with phenotypic adaptation of G127V mutant MEFs by comparing transcriptional profiles of early and late passage G127V MEFs with WT cells.
2025-01-22 | GSE255810 | GEO
Project description:Methylotuvimicrobium buryatense 5G strain:5G Genome sequencing and assembly
| PRJNA89087 | ENA
Project description:Friedreich's ataxia (FRDA) is an autosomal-recessive neurodegenerative and cardiac disorder which occurs when transcription of the frataxin (FXN) gene is silenced due to the expansion of GAA·TTC repeats in intron 1 of the same gene, leading loss of the essential mitochondrial protein frataxin with several impairment in iron metabolism and respiration, primarily affects the sensory DRG neurons. A major limitation in the study of FRDA is the lack of robust animal and cellular models. To fill this gap, this study presents a novel 3D protocol to generate dorsal root ganglia-like organoids (DRGOs) from human iPSCs in which to model Friedreich's ataxia. DRGOs show a robust expression pattern of peripheral markers, are electro-physiologically active and out-perform peripheral sensory neurons generated with a traditional 2D protocol. Furthermore, when co-cultured with human stretch receptor intrafusal muscle fibers, DRGOs contact their peripheral target and form an in vitro muscle spindle. DRGOs generated from FRDA patient-derived iPSCs recapitulate several aspects of FRDA pathology including reduced expression of FXN and TCA-cycle components and mitochondrial fragmentation. We present also the recovery of this pathological signs, achieved by a new CRISPR-Cas9 mediated deletion of the GAA·TTC tract along with the majority of the affected intron. FRDA patient edited DRGOs with the long deletion boast normalized markers of oxidative stress, as well as recovered mitochondrial defect, particularly in the axonal compartment.
2020-07-27 | GSE133755 | GEO
Project description:Friedreich's ataxia (FRDA), the most common inherited ataxia in humans, is caused by recessive mutations that lead to a substantial reduction in the levels of frataxin (FXN), a mitochondrial iron binding protein. FRDA is a multi-system disease, involving multiple neurological, cardiac, and metabolic manifestations whose study is hindered by a paucity of animal models that faithfully recapitulate human disease features. We developed an inducible (doxycycline) mouse model of Fxn deficiency (FRDAkd) that enabled us to control the onset, progression and potential rescue of disease phenotypes by the modulation of Fxn levels using RNA interference. We found that systemic knockdown of Fxn in adult mice led to multiple features paralleling those observed in human patients, including electrophysiological, cellular, biochemical and structural phenotypes associated with cardiomyopathy, as well as dorsal root ganglion and retinal neuronal degeneration and reduced axonal size and myelin sheath thickness in the spinal cord. Fxn knockdown mice also exhibited other abnormalities similar to patients, including weight loss, reduced locomotor activity, ataxia, reduced muscular strength, and reduced survival, as well as genome-wide transcriptome changes. We performed microarray analysis of heart, cerebellum and dorsal root ganglia in FRDAkd mouse model of frataxin deficiency, and found several molecular pathway dysfunction via genome-wide transcriptome analyses. We also found that, upon restoration of near wild-type FXN levels, we observed significant recovery of function, pathology and associated transcriptomic changes, even after significant motor dysfunction was observed. The rapidity of Fxn expression due to doxycycline removal and its robust correction of various parameters, even when restored after the onset of motor dysfunction, makes this FRDAkd mouse model an appealing potential preclinical tool for testing various therapeutics for FRDA.
2017-12-19 | GSE98790 | GEO
Project description:Friedreich's Ataxia (FRDA), a rare, inherited, progressive degenerative disease, is caused by a defective expression of mitochondrial protein frataxin (FXN), due to homozygous hyper-expansion of GAA triplets in the gene which severely reduce its transcription. FXN is crucial for cell survival and its deficiency in humans critically affects viability of neurons, cardiomyocytes and pancreatic beta cells. Around two thirds of individuals with FRDA show typical manifestation of hypertrophic cardiomyopathy, that can progress in heart failure and death. Except for FXN, very few genes have been correlated with ataxia and cardiac disease in FRDA. To identify other genes involved in pathogenesis of FRDA, a microarray analysis on FRDA patient's lymphoblastoid cells stably reconstituted with FXN was performed. HS-1 associated protein X-1 (HAX-1), a family of proteins playing important roles in the protection of cardiomyocytes from apoptosis, is the highest up-regulated transcript (FC=+2, p<0.0006). HAX-1 is highly expressed in heart and HAX-1 heterozygous-deficient hearts exhibit increases in infarct size. The microarray result was further assessed with qRT-PCR and western blot analysis performed on HEK293 stably transfected with empty vector or FXN-vector and lymphoblasts from FRDA patients compared to clinically unaffected heterozygous parents, confirming a strong co-expression of HAX-1 and FXN both at mRNA and protein level. Moreover, analysis of FXN and HAX-1 in peripheral blood mononuclear cells (PBMCs) of FRDA patients (n=13), heterozygous parents (n=6) and non-correlated healthy controls (n=13) revealed that their expressions are correlated. The positive correlation is more significant in FRDA patients showing a cardiac disease (10/13). The positive correlation between frataxin and HAX-1 expression level suggests a potential link of HAX-1 expression to pro-survival or protective cellular pathways related to frataxin. Thus, HAX-1 may be considered a specific biomarker of cardiomyopathy in FRDA and may represent a prognostic implement in these patients. Moreover, the discovery of novel genetic "risk" or "protective" factors in cardiomyopathy is crucial to improve risk stratification strategies and to identify new therapeutic targets.
2019-12-31 | GSE108200 | GEO
Project description:We set out to investigate whether a histone deacetylase inhibitor (HDACi) would be effective in an in vitro model for the neurodegenerative disease Friedreich ataxia (FRDA) and to evaluate safety and surrogate markers of efficacy in a phase I clinical trial in patients. In the neuronal cell model, HDACi 109/RG2833 increases FXN mRNA levels and frataxin protein, with concomitant changes in the epigenetic state of the gene. Chromatin signatures indicate that histone H3 lysine 9 is a key residue for gene silencing through methylation and reactivation through acetylation, mediated by the HDACi. Drug treatment in FRDA patients demonstrated increased FXN mRNA and H3 lysine 9 acetylation in peripheral blood mononuclear cells. No safety issues were encountered. We used a human FRDA neuronal cell model, derived from patient induced pluripotent stem cells, to determine the efficacy of a 2-aminobenzamide HDACi (109) as a modulator of FXN gene expression and chromatin histone modifications. FRDA patients were dosed in 4 cohorts, ranging from 30mg/day to 240mg/day of the formulated drug product of HDACi 109, RG2833. Patients were monitored for adverse effects as well as for increases in FXN mRNA, frataxin protein, and chromatin modification in blood cells. Gene expression profiles were obtained using the Illumina HT12v4 Gene Expression BeadArray.
2015-01-29 | E-GEOD-65399 | biostudies-arrayexpress
Project description:The molecular mechanisms of reduced frataxin (FXN) expression in Friedreich's ataxia (FRDA) are linked to epigenetic modification of the FXN locus caused by the disease-associated GAA expansion. Here, we identify that SUV4-20 histone methyltransferases, specifically SUV4-20 H1, play an important role in the regulation of FXN expression and represent a novel therapeutic target. Using a human FXN-GAA-Luciferase repeat expansion genomic DNA reporter model of FRDA, we screened the Structural Genomics Consortium epigenetic probe collection. We found that pharmacological inhibition of the SUV4-20 methyltransferases by the tool compound A-196 increased the expression of FXN by ∼1.5-fold in the reporter cell line. In several FRDA cell lines and patient-derived primary peripheral blood mononuclear cells, A-196 increased FXN expression by up to 2-fold, an effect not seen in WT cells. SUV4-20 inhibition was accompanied by a reduction in H4K20me2 and H4K20me3 and an increase in H4K20me1, but only modest (1.4-7.8%) perturbation in genome-wide expression was observed. Finally, based on the structural activity relationship and crystal structure of A-196, novel small molecule A-196 analogs were synthesized and shown to give a 20-fold increase in potency for increasing FXN expression. Overall, our results suggest that histone methylation is important in the regulation of FXN expression and highlight SUV4-20 H1 as a potential novel therapeutic target for FRDA.
2020-10-08 | GSE145115 | GEO