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Assessing the effect of SUPT4H1 RNAi on the transcription of a repeat-containing reporter construct

ABSTRACT: SUPT4H1 is a transcription elongation factor comprising part of the RNA polymerase II complex. Recent studies propose a selective role for SUPT4H1 in transcription of repeat-containing transcripts, the translated products of which are a hallmark of neurodegeneration in disorders such as Huntington’s Disease and C9orf72-amyotrophic lateral sclerosis. To investigate the potential of SUPT4H1 as a therapeutic target in repeat-associated neurodegeneration, we engineered a reporter containing 71 hexanucleotide repeats (HNRs) encoding for pDi-amino acid repeats (DARPs) fused to EGFP. To approximate endogenous expression levels, the reporter also incorporated human C9orf72 intronic DNA immediately 5' of the hexanucleotide repeats. The reporter construct was integrated into the genome of HEK293t cells. We assessed the effect of depleting SUPT4H1 by RNAi interference on the transcriptome as a whole and on the DARP-EGFP reporter.

ORGANISM(S): Homo sapiens

PROVIDER: GSE121757 | GEO | 2019/01/01

REPOSITORIES: GEO

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C9orf72 BAC Transgenic Mice Display Typical Pathologic Features of ALS/FTD

Project description:Noncoding expansions of a hexanucleotide repeat (GGGGCC) in the C9orf72 gene are the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia. Here we report transgenic mice carrying a bacterial artificial chromosome (BAC) containing the full human C9orf72 gene with either a normal allele (15 repeats) or disease-associated expansion (~100â??1,000 repeats; C9-BACexp). C9-BACexp mice displayed pathologic features seen in C9orf72 expansion patients, including widespread RNA foci and repeat-associated non-ATG (RAN) translated dipeptides, which were suppressed by antisense oligonucleotides targeting human C9orf72. Nucleolin distribution was altered, supporting that either C9orf72 transcripts or RAN dipeptides promote nucleolar dysfunction. Despite early and widespread production of RNA foci and RAN dipeptides in C9-BACexp mice, behavioral abnormalities and neurodegeneration were not observed even at advanced ages, supporting the hypothesis that RNA foci and RAN dipeptides occur presymptomatically and are not sufficient to drive neurodegeneration in mice at levels seen in patients. To compare the RNA Seq profiles from the cortex and spinal cord of transgenic mice expressing unexpanded human C9orf72 (F08, n=4), expanded human C9orf72 (F112, n=3/4), and nontransgenic controls (n=4).

2016-02-10 | E-GEOD-77720 | biostudies-arrayexpress

C9orf72 BAC Transgenic Mice Display Typical Pathologic Features of ALS/FTD

Project description:Noncoding expansions of a hexanucleotide repeat (GGGGCC) in the C9orf72 gene are the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia. Here we report transgenic mice carrying a bacterial artificial chromosome (BAC) containing the full human C9orf72 gene with either a normal allele (15 repeats) or disease-associated expansion (~100–1,000 repeats; C9-BACexp). C9-BACexp mice displayed pathologic features seen in C9orf72 expansion patients, including widespread RNA foci and repeat-associated non-ATG (RAN) translated dipeptides, which were suppressed by antisense oligonucleotides targeting human C9orf72. Nucleolin distribution was altered, supporting that either C9orf72 transcripts or RAN dipeptides promote nucleolar dysfunction. Despite early and widespread production of RNA foci and RAN dipeptides in C9-BACexp mice, behavioral abnormalities and neurodegeneration were not observed even at advanced ages, supporting the hypothesis that RNA foci and RAN dipeptides occur presymptomatically and are not sufficient to drive neurodegeneration in mice at levels seen in patients.

2016-02-10 | GSE77720 | GEO

Profiling nucleo/cytoplasmic distribution of mRNAs identifies a role for the Golgi-to-ER trafficking in C9orf72 toxicity

Project description:Compelling evidence indicates that defects in nucleocytoplasmic transport contribute to the pathogenesis of amyotrophic lateral sclerosis (ALS). In particular, hexanucleotide (G4C2) repeat expansions in C9orf72, the most common cause of genetic ALS, have a widespread impact on the transport machinery that regulates the nucleocytoplasmic distribution of proteins and RNAs, thereby affecting their functions. We have previously reported that the expression of G4C2 hexanucleotide repeats in cultured human and mouse cells caused a marked accumulation of poly(A) mRNAs in cell nuclei, suggesting that mRNA trafficking is impaired by expanded C9orf72-ALS repeats. To further characterize the process, in this work we set out to systematically identify the specific mRNAs that are altered in their nucleocytoplasmic distribution in the presence of C9orf72-ALS repeats. Results from RNAseq profiling of nuclear and cytoplasmic RNA fractions obtained from cells expressing G4C231 repeats show a significant accumulation of mRNAs in the nuclei of G4C231 cells, further suggesting that nuclear retention of mRNAs is a major effect of C9orf72 expanded repeats expression. Interestingly, pathway analysis shows that mRNAs involved in ER-to-Golgi trafficking are particularly enriched among the identified mRNAs. Most importantly, functional studies in cultured cells and Drosophila indicate that the membrane trafficking route regulated by ARFGAP1, a GTPase-activating protein that associates with Golgi, is specifically affected by expanded C9orf72 repeats, as well as by C9orf72-related dipeptide repeat proteins (C9-DPRs), pointing to ER-to-Golgi vesicle-mediated transport as a target of C9orf72 toxicity.

2023-08-21 | GSE235448 | GEO

C9ORF72 Hexanucleotide Repeat Sequence Genotyping Project

Project description:C9ORF72 Hexanucleotide Repeat Sequence Genotyping Project

| PRJNA497345 | ENA

C9ORF72 Hexanucleotide Repeat Sequence Genotyping Project

Project description:C9ORF72 Hexanucleotide Repeat Sequence Genotyping Project

| PRJNA497344 | ENA

Correction of ALS-related phenotypes in iPSC-derived motor neurons carrying a hexanucleotide expansion mutation in C9orf72 by CRISPR/Cas9 genome editing and homology-directed repair

Project description:The G4C2 hexanucleotide repeat expansion (HRE) in C9orf72 is the commonest cause of familial amyotrophic lateral sclerosis (ALS). A number of different methods have been used in an attempt to generate isogenic control lines using CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 and NHEJ by deleting the repeat region without replacing it with the normal repeat size, but typically this strategy carries the risk of creating indels and genomic instability. In this study we demonstrate complete correction of an induced pluripotent stem cell (iPSC) line derived from a C9orf72-HR positive ALS patient using CRISPR/Cas9 genome editing and homology directed repair (HDR), resulting in replacement of the excised region with a donor template carrying the wild-type repeat size to maintain the genetic architecture of the locus. The isogenic correction of the C9orf72 HRE restored normal expression and methylation at the C9orf72 locus, reduced intron retention in the edited lines, and abolished pathological phenotypes associated with the C9orf72 HRE expansion in iPSC derived motor neurons (iPSMNs). RNA sequencing of the mutant line identified 2220 differentially expressed genes compared to its isogenic control. Enrichment analysis demonstrated an over-representation of ALS relevant pathways in the presence of the C9orf72 HRE, including calcium ion dependent exocytosis, synaptic transport and the KEGG ALS pathway, as well as new targets of potential relevance to ALS pathophysiology.Complete correction of the C9orf72 HRE in iPS MNs by CRISPR/Cas9 mediated HDR provides an ideal model to study the earliest effects of the hexanucleotide expansion on cellular homeostasis and the key pathways implicated in ALS pathophysiology.

2020-05-19 | GSE139144 | GEO

CRISPR-Cas9 screens in human cells and primary neurons identify modifiers of C9orf72 dipeptide repeat protein toxicity

Project description:Hexanucleotide repeat expansions in the C9orf72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9FTD/ALS). The nucleotide repeat expansions are translated into dipeptide repeat (DPR) proteins, which are aggregation-prone and may contribute to neurodegeneration. We used the CRISPR-Cas9 system to perform genome-wide gene knockout screens for suppressors and enhancers of C9orf72 DPR toxicity in human cells. We validated hits by performing secondary CRISPR-Cas9 screens in primary mouse neurons. We uncovered potent modifiers of DPR toxicity whose gene products function in nucleocytoplasmic transport, the endoplasmic reticulum (ER), proteasome, RNA processing pathways, and in chromatin modification. One modifier, TMX2, modulated the ER-stress signature elicited by C9orf72 DPRs in neurons, and improved survival of human induced motor neurons from C9orf72 ALS patients. Together, this work demonstrates the promise of CRISPR-Cas9 screens to define mechanisms of neurodegenerative diseases. This dataset contains the RNA-sequencing data used to support the conclusions from this study.

2018-02-27 | GSE109177 | GEO

C9orf72 is required for proper macrophage and microglial function in mice

Project description:Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Decreased expression of C9orf72 is seen in expansion carriers, suggesting loss of function may play a role in disease. We find that two independent mouse lines lacking the C9orf72 ortholog (3110043O21Rik) in all tissues developed normally and aged without motor neuron disease. Instead, C9orf72 null mice developed progressive splenomegaly and lymphadenopathy with accumulation of engorged macrophage-like cells. C9orf72 expression was highest in myeloid cells, and loss of C9orf72 led to lysosomal accumulation and altered immune responses in macrophages and microglia, with age-related neuroinflammation similar to C9orf72 ALS but not sporadic ALS patient tissue. Thus, C9orf72 is required for normal function of myeloid cells, and altered microglial function may contribute to neurodegeneration in C9orf72 expansion carriers.

2016-03-24 | GSE77681 | GEO

Phe-tRNA aminoacylation is disrupted by C4G2 repeat RNA C9orf72mutation associated with ALS and FTD

Project description:Expanded hexanucleotide GGGGCC repeat mutation in the C9orf72 gene is the main genetic cause of neurodegenerative diseases amyotrophic lateral sclerosis and frontotemporal dementia. Sense and antisense transcripts of the repeats form nuclear RNA foci and bind various RNA binding proteins. Sequestration of these proteins is predicted to be cytotoxic. In this study we identified proteins that bind to antisense repeat RNA with RNA pull-down assay in combination with mass spectrometry. The interactions were confirmed in human brain lysates. Among interacting proteins is phenylalanine-tRNA synthetase (FARS). We confirmed interaction with FARS in C9orf72 mutation-positive patient-derived cells with RNA fluorescent in situ hybridization in combination with immunocytochemistry and with RNA-protein proximity ligation assay. We predict this interaction impacts the function of FARS as we observed decreased levels of charged Phe-tRNA in C9orf72 mutation-positive patient-derived cells compared to control. This study shows that antisense RNA interaction with FARS could influence protein synthesis and reveals so far unknown connection between RNA repeats and aminoacil tRNA synthetases in C9orf72 mutation.

2023-09-18 | PXD024527 | Pride

iPSC derived motor neuron cultures from C9ORF72 carriers

Project description:Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative condition characterized by loss of motor neurons in the brain and spinal cord. Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9ORF72 gene are the most common cause of the familial form of ALS (C9-ALS), as well as frontotemporal lobar degeneration and other neurological diseases. How the repeat expansion causes disease remains unclear, with both loss of function (haploinsufficiency) and gain of function (either toxic RNA or protein products) proposed. We report a cellular model of C9-ALS with motor neurons differentiated from induced pluripotent stem cells (iPSCs) derived from ALS patients carrying the C9ORF72 repeat expansion. No significant loss of C9ORF72 expression was observed, and knockdown of the transcript was not toxic to cultured human motor neurons. Transcription of the repeat was increased, leading to accumulation of GGGGCC repeat–containing RNA foci selectively in C9-ALS iPSC-derived motor neurons. Repeat-containing RNA foci colocalized with hnRNPA1 and Pur-?, suggesting that they may be able to alter RNA metabolism. C9-ALS motor neurons showed altered expression of genes involved in membrane excitability including DPP6, and demonstrated a diminished capacity to fire continuous spikes upon depolarization compared to control motor neurons. Antisense oligonucleotides targeting the C9ORF72 transcript suppressed RNA foci formation and reversed gene expression alterations in C9-ALS motor neurons. These data show that patient-derived motor neurons can be used to delineate pathogenic events in ALS. Transcriptome profiling from iPSC derived motor neurons compared to controls

2013-11-07 | E-GEOD-52202 | biostudies-arrayexpress

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