Optical genome mapping for 85 samples with large repeat expansions
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ABSTRACT:
PROVIDER: PRJEB83566 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:This study tested candidate therapeutic antimiRs in a comprehensive new collection of primary myoblasts derived from myotonic dystrophy type 1 (DM1) patients. DM1 is caused by genetically unstable CTG repeat expansions in the DMPK gene and has multiple clinical presentations, likely because of variable repeat sizes at the tissue and organ levels. Expanded DMPK transcripts deplete Muscleblind-Like Splicing Regulator protein MBNL1, which in turn causes DM1 symptoms. A promising therapeutic approach increases the expression of MBNL1 by blocking natural repressors miR-23b and miR-218 employing antimiRs with chemical modifications designed for a better pharmacological profile in humans. In untreated primary cells, we demonstrate that upregulated therapeutic targets miR-23b and miR-218 and reduced MBNL1 protein levels inversely correlate with CTG repeat size, supporting that active MBNL1 protein repression synergizes with the sequestration by CUG repeats in DM1. Upon treatment with novel antimiRs, multiple readouts of RNA toxicity associated with typical DM1 alterations improved. MBNL1-dependent exon inclusions, and myoblast fusion and myotube area defects, showed robust correction over a wide range of CTG expansions. Unexpectedly, antimiR treatment also reduced DMPK transcript levels and the number of ribonuclear aggregates. Based on these data, we selected a leading antimiR for further transcriptomics characterization and demonstrated that it reversed up to 68% of dysregulated genes. The study revealed that the candidate antimiRs could provide therapy to clinically relevant DM1 forms over a wide range of repeat sizes and genetic backgrounds by simultaneously reducing MBNL1 sequestration and derepressing protein synthesis.
2024-05-01 | GSE237411 | GEO
Project description:Intermediate-length repeat expansions in ATAXIN-2 (ATXN2) are a strong genetic risk factor for amyotrophic lateral sclerosis (ALS). At the molecular level, ATXN2 intermediate expansions enhance TDP-43 toxicity and pathology. However, whether this triggers ALS pathogenesis at the cellular and functional level remains unknown. Here, we developed a human iPSC-derived model to investigate whether motor neurons derived from ALS patients carrying ATXN2 intermediate repeat expansions are transcriptomically distinct from healthy controls. For that, we performed RNA sequencing of motor neurons derived from 5 ATXN2-ALS iPSC lines and 5 healthy controls (HC).
2024-07-16 | GSE224578 | GEO
Project description:Expanded CAG/CTG repeats underlie thirteen neurological disorders, including myotonic dystrophy type 1 (DM1) and Huntington’s disease (HD). Upon expansion, CAG/CTG repeat loci acquire heterochromatic characteristics. This observation raises the hypothesis that repeat expansion provokes changes to higher-order chromatin conformation and thereby affects both gene expression in cis and the genetic instability of the repeat tract. Here we tested this hypothesis directly by performing 4C sequencing at the DMPK and HTT loci from DM1 and HD patient-derived cells. Surprisingly, chromatin contacts remain unchanged upon repeat expansion at both loci. This was true for expanded alleles with different DNA methylation levels and CTCF binding. Repeat tract sizes ranging from 15 to 1,700 repeats displayed strikingly similar chromatin interaction profiles. Moreover, the ectopic insertion of an expanded CAG repeat tract did not change the three-dimensional chromatin conformation of the surrounding genomic region. Our findings argue that extensive changes in heterochromatic properties are not enough to alter chromatin conformation at expanded CAG/CTG repeat loci. We conclude that 3D chromatin conformation is unlikely to drive repeat expansions or changes in gene expression in expanded CAG/CTG repeat disorders. This SuperSeries is composed of the SubSeries listed below.
2020-04-07 | GSE148185 | GEO
Project description:Expanded CAG/CTG repeats underlie thirteen neurological disorders, including myotonic dystrophy type 1 (DM1) and Huntington’s disease (HD). Upon expansion, CAG/CTG repeat loci acquire heterochromatic characteristics. This observation raises the hypothesis that repeat expansion provokes changes to higher-order chromatin conformation and thereby affects both gene expression in cis and the genetic instability of the repeat tract. Here we tested this hypothesis directly by performing 4C sequencing at the DMPK and HTT loci from DM1 and HD patient-derived cells. Surprisingly, chromatin contacts remain unchanged upon repeat expansion at both loci. This was true for expanded alleles with different DNA methylation levels and CTCF binding. Repeat tract sizes ranging from 15 to 1,700 repeats displayed strikingly similar chromatin interaction profiles. Moreover, the ectopic insertion of an expanded CAG repeat tract did not change the three-dimensional chromatin conformation of the surrounding genomic region. Our findings argue that extensive changes in heterochromatic properties are not enough to alter chromatin conformation at expanded CAG/CTG repeat loci. We conclude that 3D chromatin conformation is unlikely to drive repeat expansions or changes in gene expression in expanded CAG/CTG repeat disorders.
2020-04-07 | GSE148176 | GEO
Project description:Intermediate-length repeat expansions in ATAXIN-2 (ATXN2) are a strong genetic risk factor for amyotrophic lateral sclerosis (ALS). At the molecular level, ATXN2 intermediate expansions enhance TDP-43 toxicity and pathology. However, whether this triggers ALS pathogenesis at the cellular and functional level remains unknown. Here, we developed a human iPSC-derived model to investigate whether motor neurons derived from an ALS patient carrying ATXN2 intermediate repeat expansions (ALS-G) are transcriptomically distinct from a healthy control(OH2.6). For that, we generated a single cell RNA sequencing dataset consisting of a total of 384 cells.
2024-07-16 | GSE224582 | GEO
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:AAGGG repeat expansions trigger repeat-dependent synaptic dysregulation in human CANVAS Neurons [CANVAS_Control_Isogenic]
| PRJNA1043562 | ENA
Project description:AAGGG repeat expansions trigger repeat-dependent synaptic dysregulation in human CANVAS Neurons [RFC1_Knockdown]
| PRJNA1043563 | ENA
Project description:AAGGG repeat expansions trigger repeat-dependent synaptic dysregulation in human CANVAS Neurons [RFC1_Addition]
| PRJNA1043564 | ENA
Project description:Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a late onset, recessively inherited neurodegenerative disorder caused by a biallelic, non-reference pentameric CCCTT(AAGGG) repeat expansion within the second intron of replication factor complex subunit 1 (RFC1). While rare compound heterozygous CANVAS cases harbor RFC1 loss-of-function mutations alongside monoallelic repeat-expansions, RFC1 expression is maintained at normal levels in the presence of biallelic expanded repeats. To investigate how these pentameric repeats cause disease, we generated CANVAS patient iPSC derived neurons and utilized calcium imaging and transcriptomic analysis to define repeat elicited gain-of-function and loss-of-function contributions to neuronal toxicity. AAGGG repeat expansions do not alter neuronal RFC1 splicing, expression, or DNA repair pathway functions. In reporter assays, AAGGG repeats are translated into pentapeptide repeat proteins that selectively accumulate in patient brains. However, neither these proteins nor repeat RNA foci were detected in iNeurons and overexpression of these repeats in isolation did not induce neuronal toxicity. CANVAS iNeurons exhibit defects in neuronal development and diminished synaptic connectivity that is rescued by CRISPR deletion of a single expanded allele. Importantly, these deficits were not replicated by knockdown of RFC1 in control neurons and showed incomplete or no rescue upon over-expression of RFC1. These findings support a repeat-dependent and RFC1-independent mechanism as the underlying cause of neurodegeneration in CANVAS, with important implications for therapeutic development in this currently untreatable condition.
2024-09-01 | GSE248343 | GEO