Targeted reactivation of FMR1 transcription in FXS embryonic stem cells
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA438979 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR6861042.fastq.gz | Fastqsanger.gz | |||
| SRR6861043.fastq.gz | Fastqsanger.gz | |||
| SRR6861044.fastq.gz | Fastqsanger.gz | |||
| SRR6861045.fastq.gz | Fastqsanger.gz | |||
| SRR6861046.fastq.gz | Fastqsanger.gz |
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Project description:The aim of this work is to selectively increase transcription from the FMR1 locus in FXS hESC lines using CRISPR-Cas9 fused to transcriptional activators.
2018-08-31 | GSE112031 | GEO
Project description:Fragile X Syndrome (FXS) is the most common inherited cause of intellectual disability and autism. It results from expansion of a CGG nucleotide repeat in the 5' untranslated region (UTR) of FMR1. Large expansions elicit repeat and promoter hyper-methylation, heterochromatin formation, FMR1 transcriptional silencing and loss of the Fragile X protein, FMRP. Efforts aimed at correcting the sequelae resultant from FMRP loss have thus far proven insufficient, perhaps because of FMRP's pleiotropic functions. As the repeats do not disrupt the FMRP coding sequence, reactivation of endogenous FMR1 gene expression could correct the proximal event in FXS pathogenesis. Here we utilize the Clustered Regularly Interspaced Palindromic Repeats/deficient CRISPR associated protein 9 (CRISPR/dCas9) system to selectively re-activate transcription from the silenced FMR1 locus. Fusion of the transcriptional activator VP192 to dCas9 robustly enhances FMR1 transcription and increases FMRP levels when targeted directly to the CGG repeat in human cells. Using a previously uncharacterized FXS human embryonic stem cell (hESC) line which acquires transcriptional silencing with serial passaging, we achieved locus-specific transcriptional re-activation of FMR1 messenger RNA (mRNA) expression despite promoter and repeat methylation. However, these changes at the transcript level were not coupled with a significant elevation in FMRP protein expression in FXS cells. These studies demonstrate that directing a transcriptional activator to CGG repeats is sufficient to selectively reactivate FMR1 mRNA expression in Fragile X patient stem cells.
| S-EPMC6104480 | biostudies-literature
Project description:Fragile X syndrome (FXS), the most common genetic form of intellectual disability in male, is caused by the silence of FMR1. Hypermethylation of the CGG expansion mutation in the 5’UTR region of FMR1 in FXS patients was thought to epigenetically silence FMR1. Here, we applied our previously developed DNA methylation editing tool to reverse this hypermethylation event. Targeted demethylation of the CGG expansion by dCas9-Tet1/gRNA switched the heterochromatin status of the FMR1 promoter to an active chromatin status and subsequently restored FMR1 expression in FXS iPSCs. Neurons derived from methylation edited FXS iPSCs showed a similar electrophysiological property as wild-type neurons, and maintained FMR1 expression for months after engrafting into the mouse brain. Reactivation of FMR1 can be achieved in FXS neurons with demethylation of the CGG expansion. Lastly, we showed that targeted demethylation of the FMR1 promoter can reactivate FMR1 as well suggesting potential therapeutic approaches for FXS.
2018-02-16 | GSE102655 | GEO
Project description:Fragile X syndrome (FXS), the most common genetic form of intellectual disability in male, is caused by the silence of FMR1. Hypermethylation of the CGG expansion mutation in the 5’UTR region of FMR1 in FXS patients was thought to epigenetically silence FMR1. Here, we applied our previously developed DNA methylation editing tool to reverse this hypermethylation event. Targeted demethylation of the CGG expansion by dCas9-Tet1/gRNA switched the heterochromatin status of the FMR1 promoter to an active chromatin status and subsequently restored FMR1 expression in FXS iPSCs. Neurons derived from methylation edited FXS iPSCs showed a similar electrophysiological property as wild-type neurons, and maintained FMR1 expression for months after engrafting into the mouse brain. Reactivation of FMR1 can be achieved in FXS neurons with demethylation of the CGG expansion. Lastly, we showed that targeted demethylation of the FMR1 promoter can reactivate FMR1 as well suggesting potential therapeutic approaches for FXS.
2018-02-16 | GSE102684 | GEO
Project description:Fragile X syndrome (FXS), the most common genetic form of intellectual disability in male, is caused by silencing of the FMR1 gene by hypermethylation of the CGG expansion mutation in the 5’UTR region of FMR1 in FXS patients. Here, we applied recently developed DNA methylation editing tools to reverse this hypermethylation event. Targeted demethylation of the CGG expansion by dCas9-Tet1/sgRNA switched the heterochromatin status of the upstream FMR1 promoter to an active chromatin state restoring a persistent expression of FMR1 in FXS iPSCs. Neurons derived from methylation edited FXS iPSCs rescued the electrophysiological abnormalities and restored a wild-type phenotype upon the mutant neurons. FMR1 expression in edited neurons was maintained in vivo after engrafting into the mouse brain. Finally, demethylation of the CGG repeats in post-mitotic FXS neurons also reactivated FMR1. Our data establish demethylation of the CGG expansion is sufficient for FMR1 reactivation, suggesting potential therapeutic strategies for FXS.
2018-02-16 | GSE108171 | GEO
Project description:Fragile X syndrome (FXS), the most common genetic form of intellectual disability in male, is caused by silencing of the FMR1 gene by hypermethylation of the CGG expansion mutation in the 5’UTR region of FMR1 in FXS patients. Here, we applied recently developed DNA methylation editing tools to reverse this hypermethylation event. Targeted demethylation of the CGG expansion by dCas9-Tet1/sgRNA switched the heterochromatin status of the upstream FMR1 promoter to an active chromatin state restoring a persistent expression of FMR1 in FXS iPSCs. Neurons derived from methylation edited FXS iPSCs rescued the electrophysiological abnormalities and restored a wild-type phenotype upon the mutant neurons. FMR1 expression in edited neurons was maintained in vivo after engrafting into the mouse brain. Finally, demethylation of the CGG repeats in post-mitotic FXS neurons also reactivated FMR1. Our data establish demethylation of the CGG expansion is sufficient for FMR1 reactivation, suggesting potential therapeutic strategies for FXS.
2018-02-16 | GSE108498 | GEO
Project description:Fragile X syndrome (FXS) is a neurodevelopmental disorder and a leading cause of intellectual disability. In FXS, the neuronal regulator, FMR1, is epigenetically silenced by a CGG repeat expansion. Here, we investigate conditions under which repeat expansion and gene silencing could be reversed. Surprisingly, inducing formation of R-loops (3-stranded RNA-DNA structures) within FMR1 is sufficient to initiate CGG contraction, promoter demethylation, and FMR1 reactivation. Recruiting RNaseH degrades the R-loop and abolishes the response. Targeting the nascent mRNA for degradation also eliminates the response. Thus, we have identified an exogenous nuclease-free method of contracting CGG repeats and reversing FMR1 silencing. We propose that DNA demethylation, new transcription, and R-loop formation engage in a feed-forward cycle to contract CGG repeats and reactivate FMR1.
2023-05-19 | GSE184580 | GEO
Project description:Fragile X syndrome (FXS) is the most common form of inherited intellectual disability, resulting from a CGG repeat expansion in the fragile X mental retardation 1 (FMR1) gene. Here we report a strategy for CGG repeat correction using CRISPR/Cas9 for targeted deletion in both embryonic stem cells and induced pluripotent stem cells derived from FXS patients. Following gene correction in FXS induced pluripotent stem cells, FMR1 expression was restored and sustained in neural precursor cells and mature neurons. Strikingly, after removal of the CGG repeats, the upstream CpG island of the FMR1 promoter showed extensive demethylation, an open chromatin state, and transcription initiation. These results suggest a silencing maintenance mechanism for the FMR1 promoter that is dependent on the existence of the CGG repeat expansion. Our strategy for deletion of trinucleotide repeats provides further insights into the molecular mechanisms of FXS and future therapies of trinucleotide repeat disorders.
2015-08-18 | GSE72114 | GEO
Project description:Fragile X syndrome (FXS) is caused primarily by a CGG repeat expansion mutation in the FMR1 gene that triggers its epigenetic silencing. In order to investigate the role of different epigenetic regulatory layers in the silencing of FMR1 expression, we tested a collection of epigenetic modulators for the ability to reactivate the FMR1 locus. While inhibitors of DNA methylatransferase induced the highest levels of FMR1 mRNA expression, a combination of a DNMT inhibitor and a novel epigenetic agent was able to potentiate the effect of reactivating treatment. To better assess the rescue effect observed following direct demethylation, we characterized the long-term and genome-wide effects of FMR1 reactivation, and established an in vivo system for FMR1 reactivating therapy analysis. Systemic treatment with a DNMT inhibitor in mice carrying transplants of differentiated FXS-iPSCs was able to robustly induce FMR1 expression in the affected tissue, which was maintained for a prolonged period of time. Finally, we show a proof-of-principle for FMR1 reactivating therapy in the context of the central nervous system.
2019-03-06 | GSE112145 | GEO
Project description:Aberrant alternative splicing of mRNAs results in dysregulated gene expression in multiple neurological disorders. Here we show that hundreds of mRNAs are incorrectly expressed and spliced in white blood cells and brain tissue of individuals with fragile X syndrome (FXS). Surprisingly, the FMR1 (Fragile X Messenger Ribonucleoprotein 1) gene is transcribed in >70% of the FXS tissues. In all FMR1 expressing FXS tissues, FMR1 RNA itself is mis-spliced in a CGG expansion-dependent manner to generate the little-known FMR1-217 RNA isoform, which is comprised of FMR1 exon 1 and a pseudo-exon in intron 1. FMR1-217 is also expressed in FXS premutation carrier-derived skin fibroblasts and brain tissue. We show that in cells aberrantly expressing mis-spliced FMR1, antisense oligonucleotide (ASO) treatment reduces FMR1-217, rescues full-length FMR1 RNA, and restores FMRP (Fragile X Messenger RibonucleoProtein) to normal levels. Notably, FMR1 gene reactivation in transcriptionally silent FXS cells using 5-aza-2′-deoxycytidine (5-AzadC), which prevents DNA methylation, increases FMR1-217 RNA levels but not FMRP. ASO treatment of cells prior to 5-AzadC application rescues full-length FMR1 expression and restores FMRP. These findings indicate that mis-regulated RNA processing events in blood could serve as potent biomarkers for FXS and that in those individuals expressing FMR1-217, ASO treatment may offer a new therapeutic approach to mitigate the disorder.
2023-06-14 | GSE202178 | GEO