Project description:C. elegans mutants deleted for TDP-1, an ortholog of the neurodegeneration-associated RNA binding protein TDP-43, display only mild phenotypes. Nevertheless, transcriptome sequencing revealed that many RNAs were altered in accumulation and/or processing in the mutant. Analysis of these transcriptional abnormalities demonstrates that a primary function of TDP-1 is to limit formation or stability of double-stranded RNA. Specifically, we found that deletion of tdp-1: 1) preferentially alters the accumulation of RNAs with inherent double stranded structure (dsRNA); 2) increases the accumulation of nuclear dsRNA foci, 3) enhances the frequency of adenosine-to-inosine RNA editing, and 4) dramatically increases the amount of transcripts immunoprecipitable with a dsRNA-specific antibody, including intronic sequences, RNAs with antisense overlap to another transcript, and transposons. We also show that TDP-43 knockdown in human cells results in accumulation of dsRNA , indicating that suppression of dsRNA is a conserved function of TDP-43 in mammals. Altered accumulation of structured RNA may account for some of the previously described molecular phenotypes (e.g., altered splicing) resulting from reduction of TDP-43 function.
Project description:C. elegans mutants deleted for TDP-1, an ortholog of the neurodegeneration-associated RNA binding protein TDP-43, display only mild phenotypes. Nevertheless, transcriptome sequencing revealed that many RNAs were altered in accumulation and/or processing in the mutant. Analysis of these transcriptional abnormalities demonstrates that a primary function of TDP-1 is to limit formation or stability of double-stranded RNA. Specifically, we found that deletion of tdp-1: 1) preferentially alters the accumulation of RNAs with inherent double stranded structure (dsRNA); 2) increases the accumulation of nuclear dsRNA foci, 3) enhances the frequency of adenosine-to-inosine RNA editing, and 4) dramatically increases the amount of transcripts immunoprecipitable with a dsRNA-specific antibody, including intronic sequences, RNAs with antisense overlap to another transcript, and transposons. We also show that TDP-43 knockdown in human cells results in accumulation of dsRNA , indicating that suppression of dsRNA is a conserved function of TDP-43 in mammals. Altered accumulation of structured RNA may account for some of the previously described molecular phenotypes (e.g., altered splicing) resulting from reduction of TDP-43 function. 24 samples: 3 tdp-1 polyA samples with 3 N2 controls, 3 tdp1J2 immunoprecipitated samples and tdp1 total RNA input with 3 N2 J2 immunoprecipitated controls (with N2 input), 3 tdp1 total RNA samples for RNA editing analysis with 3 N2 total RNA controls and an adr-2 mutant control, 2 tdp1 CHIPseq samples with RNAsecontrol.
Project description:TDP-1 is the C. elegans ortholog of mammalian TDP-43, which is strongly implicated in the etiology of Frontotemporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). We discovered that deletion of the tdp-1 gene results in enhanced transcriptional gene silencing leading to increased sensitivity to heritable RNA interference (RNAi). As heritable RNAi in C. elegans depends on chromatin changes moderated by HPL-2, a homolog of heterochromatin protein 1 (HP1), we investigated the interaction of TDP-1 and HPL-2. We find that TDP-1 and HPL-2 interact directly, and loss of TDP-1 dramatically alters the chromatin association of HPL-2. We have shown previously that deletion of the tdp-1 gene results in transcriptional alterations and the accumulation of double-stranded (ds) RNA. These molecular changes are replicated in an hpl-2 deletion strain, consistent with HPL-2 acting downstream of TDP-1 to modulate these aspects of RNA metabolism. Our observations identify novel mechanisms by which HP1 homologs can be recruited to chromatin, and by which nuclear depletion of human TDP-43 could lead to disease-relevant changes in RNA metabolism.
Project description:Transactive response DNA-binding protein of 43 kDa (TDP-43), a heterogeneous nuclear ribonucleoprotein (hnRNP) with diverse activities, is a common denominator in several neurodegenerative disorders including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Orthologs of TDP-43 exist from mammals to invertebrates, but their functions in lower organisms remain poorly understood. Here we systematically studied mutant Caenorhabditis elegans lacking the nematode TDP-43 ortholog, TDP-1. To understand the global gene expression regulation induced by the loss of tdp-1, the C. elegans transcriptomes were compared between the N2 WT animals and the tdp-1(ok803lf) mutant. Transcriptional profiling demonstrated that the loss of TDP-1 altered expression of genes functioning in RNA processing and protein folding. These results suggest that the C. elegans TDP-1 as an RNA-processing protein may have a role in the regulation of protein homeostasis and aging. Global gene expression profiling was performed to compare the transcriptome of wild-type (N2) Caenorabditis elegans and that of tdp-1(ok803) loss-of-function mutant. We analyzed mixed stages of Caenorabditis elegans, wild-type N2 versus tdp-1(ok803), using the Affymetrix C. elegans genome array. Three biological replicates were performed.
Project description:Transactive response DNA-binding protein of 43 kDa (TDP-43), a heterogeneous nuclear ribonucleoprotein (hnRNP) with diverse activities, is a common denominator in several neurodegenerative disorders including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Orthologs of TDP-43 exist from mammals to invertebrates, but their functions in lower organisms remain poorly understood. Here we systematically studied mutant Caenorhabditis elegans lacking the nematode TDP-43 ortholog, TDP-1. To understand the global gene expression regulation induced by the loss of tdp-1, the C. elegans transcriptomes were compared between the N2 WT animals and the tdp-1(ok803lf) mutant. Transcriptional profiling demonstrated that the loss of TDP-1 altered expression of genes functioning in RNA processing and protein folding. These results suggest that the C. elegans TDP-1 as an RNA-processing protein may have a role in the regulation of protein homeostasis and aging. Global gene expression profiling was performed to compare the transcriptome of wild-type (N2) Caenorabditis elegans and that of tdp-1(ok803) loss-of-function mutant.
Project description:We observed that heat shock of Caenorhabditis elegans leads to the formation of nuclear double-stranded RNA (dsRNA) foci, detectable with a dsRNA-specific monoclonal antibody. These foci significantly overlap with nuclear HSF-1 granules. To investigate the molecular mechanism(s) underlying dsRNA foci formation, we used RNA-seq to globally characterize total RNA and immunoprecipitated dsRNA from control and heat-shocked worms. We find antisense transcripts are generally increased after heat shock, and a subset of both sense and antisense transcripts enriched in the dsRNA pool by heat shock overlap with dsRNA transcripts enriched by deletion of tdp-1, which encodes the C. elegans ortholog of TDP-43. Interestingly, transcripts involved in translation are over-represented in the dsRNAs induced by either heat shock or deletion of tdp-1. Also enriched in the dsRNA transcripts are sequences downstream of annotated genes (DoGs), which we globally quantified with a new algorithm. To validate these observations, we used fluorescence in situ hypridization (FISH) to confirm both antisense and downstream of gene transcription for eif-3.B, one of the affected loci we identified.
Project description:TDP-43 is an RNA binding protein involved in amyotrophic lateral sclerosis and other neurodegenerative diseases. The purpose of this study was to determine if loss of TDP-43 function leads to accumulation of repetitive element transcripts, double-stranded RNA (dsRNA) and innate immune activation that may be involved in disease pathology. TDP-43 was knocked down in primary rat astrocytes via siRNA, cells were treated with/without ATP (an immune modulator), and polyA RNA-seq was performed to profile gene expression. Immunoprecipitation/RNA-seq was also performed using a dsRNA-specific antibody to identify potential dsRNAs resulting from TDP-43 knockdown.