CAG repeat-binding small molecule improves repeat-length-dependent dysregulation of gene expression profiles in a mouse model of Dentatorubral–pallidoluysian atrophy
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE183652 | GEO | 2022/09/08
REPOSITORIES: GEO
Similar Datasets
Project description:Spinocerebellar ataxia type 3 (SCA3) is one of the polyglutamine (polyQ) diseases, which are caused by a CAG repeat expansion within the coding region of the associated genes. The CAG repeat specifies glutamine, and the expanded polyQ domain with mutation confers dominant toxicity on the protein. Traditionally, studies have focused on protein toxicity in polyQ disease mechanisms. Recent findings, however, demonstrate that the CAG repeat RNA, which encodes the toxic polyQ protein, also contributes to the disease in Drosophila. To provide insight into the nature of the RNA toxicity, we extracted brain-enriched RNA from flies expressing a toxic CAG repeat mRNA (CAG100) and a non-toxic interrupted CAA/G mRNA repeat (CAA/G105) for microarray analysis. This approach identified a set of genes that are differentially expressed specifically in CAG100 flies. Four independent replicates of flies expressing CAG0, CAG100, or CAA/G105 by elav-GAL4 were collected at 3 days. The transgenes are DsRed with either (CAG0) no CAG repeat in the 3'UTR, (CAG100) a CAG repeat of 100 CAGs in the 3'UTR, or (CAA/G105) an interrupted CAA CAG repeat in the 3'UTR (ref: Li et al., Nature 453:1107) The transgenes were adjusted to match in mRNA expression such that CAG0 flies had one copy of the transgene, CAG100 flies had 5 copies, and CAA/G105 had two copies. Fly brain tissue (about 20 brains per sample, dissected from head capsule, eyes, lamina and outer medulla removed) was dissected in cold phosphate buffered saline (PBS) and stored in Trizol reagent (Invitrogen Corporation, Carlsbad, CA) at -80Ë?C. Total brain RNA was extracted and purified using TRIzol reagent (Invitrogen) and the RNeasy Mini system (Qiagen), and treated with RNase-free DNase I (Qiagen). To define genes whose expression is altered in response to a toxic CAG repeat RNA, we compared CAG100 flies with age-matched flies expressing CAG0. To exclude transcriptional changes in response to a non-toxic trinucleotide repeat, a second gene list was generated by comparing CAA/G105 flies with age-matched CAG0 flies.
2011-11-22 | E-GEOD-31875 | biostudies-arrayexpress
Project description:Spinocerebellar ataxia type 3 (SCA3) is one of the polyglutamine (polyQ) diseases, which are caused by a CAG repeat expansion within the coding region of the associated genes. The CAG repeat specifies glutamine, and the expanded polyQ domain with mutation confers dominant toxicity on the protein. Traditionally, studies have focused on protein toxicity in polyQ disease mechanisms. Recent findings, however, demonstrate that the CAG repeat RNA, which encodes the toxic polyQ protein, also contributes to the disease in Drosophila. To provide insight into the nature of the RNA toxicity, we extracted brain-enriched RNA from flies expressing a toxic CAG repeat mRNA (CAG100) and a non-toxic interrupted CAA/G mRNA repeat (CAA/G105) for microarray analysis. This approach identified a set of genes that are differentially expressed specifically in CAG100 flies.
2011-11-22 | GSE31875 | 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:Recent data strongly suggest HTT CAG repeat expansion drives Huntington’s disease (HD) pathogenesis and that disease development is modulated by components of the DNA damage response (DDR) pathway. FAN1 has been identified as a major HD modifier which slows expansion of the HTT CAG repeat in several cell and animal HD models. Here we show dual FAN1 activities act to inhibit repeat expansion. A highly conserved SPYF motif in the FAN1 N-terminus is required for an MLH1 interaction, which slows expansion, with FAN1 nuclease activity also contributing towards repeat stabilisation. Our data supports a model where FAN1 binds MLH1, restricting its recruitment by MSH3 and the formation of the functional DNA mismatch repair (MMR) complex believed to promote CAG repeat expansion. FAN1 nuclease activity functions either concurrently or following MMR activity to maintain repeat stability. These data highlight a potential avenue for HD therapeutics in attenuating somatic expansion.
2022-02-16 | PXD023221 | Pride
Project description:In Huntington’s disease (HD), expanded HTT CAG repeat length correlates strongly with age at motor onset, indicating that it determines the rate of the disease process leading to diagnostic clinical manifestations. Similarly, in normal individuals, HTT CAG repeat length is correlated with biochemical differences that reveal it as a functional polymorphism. Here, we tested the hypothesis that gene expression signatures can capture continuous, length-dependent effects of the HTT CAG repeat. Using gene expression datasets for 107 HD and control lymphoblastoid cell lines, we constructed mathematical models in an iterative manner, based upon CAG correlated gene expression patterns in randomly chosen training samples, and tested their predictive power in test samples. Predicted CAG repeat lengths were significantly correlated with experimentally determined CAG repeat lengths, whereas models based upon randomly permuted CAGs were not at all predictive. Predictions from different batches of mRNA for the same cell lines were significantly correlated, implying that CAG length-correlated gene expression is reproducible. Notably, HTT expression was not itself correlated with HTT CAG repeat length. Taken together, these findings confirm the concept of a gene expression signature representing the continuous effect of HTT CAG length and not primarily dependent on the level of huntingtin expression. Such global and unbiased approaches, applied to additional cell types and tissues, may facilitate the discovery of therapies for HD by providing a comprehensive view of molecular changes triggered by HTT CAG repeat length for use in screening for and testing compounds that reverse effects of the HTT CAG expansion. To evaluate the continuous analytical approach as a strategy to discover the molecular consequences of the HTT CAG repeat, genome-wide gene expression datasets were generated from a panel of 107 human lymphoblastoid cell lines with HTT CAGs spanning the entire spectrum of allele sizes.
2013-05-03 | E-GEOD-34721 | biostudies-arrayexpress
Project description:In Huntington’s disease (HD), expanded HTT CAG repeat length correlates strongly with age at motor onset, indicating that it determines the rate of the disease process leading to diagnostic clinical manifestations. Similarly, in normal individuals, HTT CAG repeat length is correlated with biochemical differences that reveal it as a functional polymorphism. Here, we tested the hypothesis that gene expression signatures can capture continuous, length-dependent effects of the HTT CAG repeat. Using gene expression datasets for 107 HD and control lymphoblastoid cell lines, we constructed mathematical models in an iterative manner, based upon CAG correlated gene expression patterns in randomly chosen training samples, and tested their predictive power in test samples. Predicted CAG repeat lengths were significantly correlated with experimentally determined CAG repeat lengths, whereas models based upon randomly permuted CAGs were not at all predictive. Predictions from different batches of mRNA for the same cell lines were significantly correlated, implying that CAG length-correlated gene expression is reproducible. Notably, HTT expression was not itself correlated with HTT CAG repeat length. Taken together, these findings confirm the concept of a gene expression signature representing the continuous effect of HTT CAG length and not primarily dependent on the level of huntingtin expression. Such global and unbiased approaches, applied to additional cell types and tissues, may facilitate the discovery of therapies for HD by providing a comprehensive view of molecular changes triggered by HTT CAG repeat length for use in screening for and testing compounds that reverse effects of the HTT CAG expansion.
2013-05-03 | GSE34721 | GEO
Project description:HuntingtonÂs disease (HD) is a devastating neurodegenerative disease, with out effective treatment. Despite significant advances, our understanding of how an expanded CAG repeat in the amino terminus of the large ubiquitously expressed HD gene product remains incomplete. Augmented adult neurogenesis in response to acute and chronic injury, including HuntingtonÂs disease, has been demonstrated, but its role development, disease, and recovery is largely unknown, as are the factors controlling it. The HD gene product, huntingtin (htt) is know to interact with a number of transcription factors which subsequently influence gene expression. Understanding the factors involved in controlling neurogenesis in response to disease would bridge a significant knowledge gap and have tremendous therapeutic potential. We propose to identify transcripts responsible for CAG repeat facilitated neurogenesis. Our hypothesis is that expanded CAG repeats in the HuntingtonÂs disease gene facilitates neurogenesis by altering transcription of genes critical in neurogenesis. We have developed a model in which mouse embryonic stem cells (ESC) with expanded CAG repeats have facilitated neurogenesis. In this model more ESC with expanded CAG repeats transition to neuronal precursors and then develop into mature neurons more rapidly than control ESC. We propose to compare the gene expression profiles between ESC with expanded CAG repeats and control ESCs on days 4 and 6 of neuronal differentiation. Initial studies indicate that key transcriptional differences are occurring at these time points. Control ECS and a an ESC line with150 CAG repeats will be differentiated in triplicate, and RNA isolated form each replicate. It is anticipated that comparison of gene expression between the control and CAG repeat lines at each time point will identify transcripts involved in CAG repeat facilitated neurogenesis. Observed differences at day 4 may be more relevant to the transition from ESC to neuronal precursor whereas differences at day 6 may be more relevant to the neuronal precursor to neuron transition.
2008-06-16 | E-GEOD-9760 | biostudies-arrayexpress
Project description:Recent evidence supports a role for RNA as a common pathogenic agent in both the “polyglutamine” and “untranslated” dominant expanded repeat disorders. One feature of all repeat sequences currently associated with disease is their predicted ability to form a hairpin secondary structure at the RNA level. In order to investigate mechanisms by which hairpin forming repeat RNAs could induce neurodegeneration, we have looked for alterations in gene transcripts as hallmarks of the cellular response to toxic hairpin repeat RNAs. Three disease associated repeat sequences - CAG, CUG and AUUCU - were specifically expressed in the neurons of Drosophila and resultant common, early, transcriptional changes assessed by microarray analyses. Transcripts that encode several components of the Akt/Gsk3-β signalling pathway were altered as a consequence of expression of these repeat RNAs, indicating that this pathway is a component of the neuronal response to these pathogenic RNAs and may represent an important common therapeutic target in this class of diseases. The heads from newly eclosed Male Drosophila were used for RNA extraction and profiling on Affymetrix Drosophile Genome 2.0 microarrays. Twenty samples were analysed, representing control and experimental lines. Two independently derived control lines were used in each exeriment, totaling 4 samples. The tri-nucleotide repeats (CAG, CUG, CAA) were represented by three independently derived two transgene insertion lines each in one experiment and two independent four transgene insertion lines each in a second experiment, totaling 15 samples. A single four transgene insertion line was analysed for AUUCU. Candidates were selected from the pool of transcripts which showed a ‘present’ call in either all independent lines for a particular repeat sequence, or in all samples for the elav- GAL4/+ control in that experiment. Where possible, T-tests were performed on raw values to determine samples that showed a significant difference with a P-value < 0.05.
2011-04-28 | E-GEOD-27178 | biostudies-arrayexpress
Project description:Huntingtons disease (HD) is a devastating neurodegenerative disease, with out effective treatment. Despite significant advances, our understanding of how an expanded CAG repeat in the amino terminus of the large ubiquitously expressed HD gene product remains incomplete. Augmented adult neurogenesis in response to acute and chronic injury, including Huntingtons disease, has been demonstrated, but its role development, disease, and recovery is largely unknown, as are the factors controlling it. The HD gene product, huntingtin (htt) is know to interact with a number of transcription factors which subsequently influence gene expression. Understanding the factors involved in controlling neurogenesis in response to disease would bridge a significant knowledge gap and have tremendous therapeutic potential. We propose to identify transcripts responsible for CAG repeat facilitated neurogenesis. Our hypothesis is that expanded CAG repeats in the Huntingtons disease gene facilitates neurogenesis by altering transcription of genes critical in neurogenesis. We have developed a model in which mouse embryonic stem cells (ESC) with expanded CAG repeats have facilitated neurogenesis. In this model more ESC with expanded CAG repeats transition to neuronal precursors and then develop into mature neurons more rapidly than control ESC. We propose to compare the gene expression profiles between ESC with expanded CAG repeats and control ESCs on days 4 and 6 of neuronal differentiation. Initial studies indicate that key transcriptional differences are occurring at these time points. Control ECS and a an ESC line with150 CAG repeats will be differentiated in triplicate, and RNA isolated form each replicate. It is anticipated that comparison of gene expression between the control and CAG repeat lines at each time point will identify transcripts involved in CAG repeat facilitated neurogenesis. Observed differences at day 4 may be more relevant to the transition from ESC to neuronal precursor whereas differences at day 6 may be more relevant to the neuronal precursor to neuron transition. Keywords: time-course
2007-12-04 | GSE9760 | GEO
Project description:Recent evidence supports a role for RNA as a common pathogenic agent in both the “polyglutamine” and “untranslated” dominant expanded repeat disorders. One feature of all repeat sequences currently associated with disease is their predicted ability to form a hairpin secondary structure at the RNA level. In order to investigate mechanisms by which hairpin forming repeat RNAs could induce neurodegeneration, we have looked for alterations in gene transcripts as hallmarks of the cellular response to toxic hairpin repeat RNAs. Three disease associated repeat sequences - CAG, CUG and AUUCU - were specifically expressed in the neurons of Drosophila and resultant common, early, transcriptional changes assessed by microarray analyses. Transcripts that encode several components of the Akt/Gsk3-β signalling pathway were altered as a consequence of expression of these repeat RNAs, indicating that this pathway is a component of the neuronal response to these pathogenic RNAs and may represent an important common therapeutic target in this class of diseases.
2011-04-28 | GSE27178 | GEO