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: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:Tissue-specific chromatin binding patterns of C. elegans heterochromatin proteins HPL-1 and HPL-2 reveal differential roles in the regulation of gene expression.
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:The human Tar-DNA-binding protein TDP-43 is closely associated with ALS and other neurodegenerative disorders. TDP-43 contains two highly conserved RNA-binding motifs and possesses a variety of documented roles in RNA metabolism, including pre-RNA splicing and repression of transcription. We sought to measure the effect that knockout and over-expression of the fly orthologue of this protein, Tar-DNA-binding protein homolog (TBPH), has on the transcriptome of the central nervous system (CNS) of Drosophila melanogaster. To this end, we used massively parallel sequencing methods (RNA-seq) to transcriptionally profile the CNS in loss-of-function mutants and gain-of-function over-expression genotypes. We found that loss of TBPH resulted in widespread gene activation, much of which could be reversed by rescue of TBPH expression, suggesting that repression is one of the major roles of TBPH. Conversely, we found that over-expression of TBPH resulted largely in decreased gene expression. However, there was little overlap in the genes which were affected in these two genotypes, suggesting that the bulk of genes affected by TBPH loss-of-function and over-expression are different. We provide a comprehensive look at enriched gene ontologies in both cases, suggesting that TDP-43 plays a role in regulating basic processes in neurons. We also describe a number of genes whose splicing is likely to be altered in the absence of TDP-43. In this study we compare the effects of knockout of the TDP-43 ortholog (TBPH) in the fly nervous system with the effects of its overexpression. 2 treatment groups are presented. In the first, TDP-43 knockout (G2) is compared to control (A1) and rescue (G2; TDP-43-GAL4>UAS-TDP-43). In the second comparison, the motor neuron driver D42-GAL4 is used to overexpress TDP-43 in motor neurons, using LacZ as a control for overexpression of a foreign protein.