RIP-Seq analysis of Trypanosoma brucei ELAV-like protein Tb927.8.6650
Ontology highlight
ABSTRACT:
ORGANISM(S): Trypanosoma brucei
SUBMITTER: Hamed Najafabadi
PROVIDER: E-GEOD-46160 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:During the bloodstream stage of the Trypanosoma brucei lifecycle, the parasite exists as the proliferative slender-form or the non-proliferative, transmissible, stumpy-form. The transition from the slender to stumpy-form is stimulated by a density-dependent mechanism and is important in infection dynamics, ordered antigenic variation and disease transmissibility. Here, we use a monomorphic reporter cell line in a whole-cell fluorescence-based assay to screen over 6000 small molecules from a kinase-focussed compound library for their ability to induce stumpy-like formation in a high-throughput screening programme. This identified one compound able to induce modest, yet specific, changes in gene expression indicative of a partial differentiation to stumpy forms. This not only provides a potential tool for the further understanding of stumpy formation, but also demonstrates the use of high throughput screening in the identification of compounds able to induce specific phenotypes, such as differentiation, in African trypanosomes. Examination of gene expression in response to treatment with DDD00015314.
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Project description:Post-transcriptional regulons coordinate the expression of groups of genes in eukaryotic cells, yet relatively few have been characterised. Parasitic trypanosomatids are particularly good models for studies on such mechanisms because they exhibit almost exclusive polycistronic, and unregulated, transcription. Here, we identify the Trypanosoma brucei ZC3H39/40 RNA-binding proteins as regulators of the respiratome; the mitochondrial electron transport chain (complexes I-IV) and the FoF1-ATP synthase (complex V). A high-throughput RNAi screen initially implicated both ZC3H proteins in variant surface glycoprotein (VSG) gene silencing. This link was confirmed and both proteins were shown to form a cytoplasmic ZC3H39/40 complex. Transcriptome and mRNA-interactome analyses indicated that the impact on VSG silencing was indirect, while the ZC3H39/40 complex specifically bound and stabilised transcripts encoding respiratome-complexes. Quantitative proteomic analyses revealed specific positive control of respiratome protein abundance. Our findings establish a link between the mitochondrial respiratome and VSG gene silencing. They also reveal a major respiratome regulon controlled by the conserved trypanosomatid ZC3H39/40 RNA-binding proteins.
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Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2013-04-18 | E-GEOD-46162 | biostudies-arrayexpress
Project description:Three potential ELAV-like proteins of T. brucei, including Tb927.3.2930, Tb927.7.5380, and Tb927.8.6650, were either inhibited by RNAi or phenotypically activated by over-expression, followed by microarray analysis of the transcriptome. The results indicated that these ELAV-like proteins regulate the abundance of a large number of T. brucei transcripts, potentially through regulation of mRNA stability. Each of the three ELAV-like proteins were either inhibited by RNAi or over-expressed, in stable transgenic procyclic form cell lines. Total RNA was extracted 48h after tetracycline induction of the constructs (except for total RNA from Tb927.8.6650 RNAi which was extracted 24h after tet-induction), and sent to NimbleGen for cDNA synthesis and hybridization. Non-induced cells were analyzed in parallel.
2013-04-18 | E-GEOD-46161 | biostudies-arrayexpress
Project description:The parasite Trypanosoma brucei periodically changes the expression of protective variant surface glycoproteins (VSGs) to evade its host’s immune system in a process known as antigenic variation. One route to change VSG expression is the transcriptional activation of a previously silent VSG expression site (ES), a subtelomeric region containing the VSG genes. Homologous recombination of a different VSG from a large reservoir into the active ES represents another route. The conserved histone methyltransferase DOT1B is involved in transcriptional silencing of inactive ES and influences ES switching kinetics. The molecular machinery that enables DOT1B to execute these regulatory functions remains elusive, however. To better understand DOT1B-mediated regulatory processes, we purified DOT1B-associated proteins using complementary biochemical approaches. We identified several novel DOT1B-interactors. One of these was the Ribonuclease H2 complex, previously shown to resolve RNA-DNA hybrids, maintain genome integrity, and play a role in antigenic variation. Our study revealed that DOT1B depletion results in an increase in RNA-DNA hybrids, accumulation of DNA damage and ES switching events. Surprisingly, a similar pattern of VSG deregulation was observed in Ribonuclease H2 mutants. We propose that both proteins act together in resolving R-loops to ensure genome integrity and contribute to the tightly-regulated process of antigenic variation.
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Project description:The parasite Trypanosoma brucei periodically changes the expression of its protective variant surface glycoproteins (VSGs) to evade the host’s immune system in a process known as antigenic variation. One route to change VSG expression is by transcriptional activation of a previously silent VSG expression site (ES), a subtelomeric region containing the VSG genes. Homologous recombination of a different VSG from a large reservoir into the active ES represents another route. The conserved histone methyltransferase DOT1B is involved in transcriptional silencing of inactive ES and influences ES switching kinetics. The molecular machinery that enables DOT1B to execute these regulatory functions remains elusive, however. To better understand DOT1B-mediated regulatory processes, we purified DOT1B-associated proteins using complementary biochemical approaches. We identified several novel DOT1B interactors. One of these was the trimeric Ribonuclease H2 complex, previously shown to resolve RNA-DNA hybrids, maintain genome integrity, and play a role in antigenic variation. Our study revealed that DOT1B depletion results in an increase in RNA-DNA hybrids, accumulation of DNA damage and recombination-based ES switching events. Surprisingly, the observed VSG deregulation was similar to Ribonuclease H2 mutants. We here propose that the epigenetic regulator DOT1B forms a complex with RNase H2 that acts in resolving R-loops to ensure genome integrity and contribute to the tightly regulated process of antigenic variation.
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Project description:A procyclic form Trypansome brucei RNAi line (PTT parental line, transfected with pALC14 incorporating a TbNMD3 gene fragment) capable of inducing depletion of TbNMD3 was analysed for mRNA expression by RNAseq Cells were grown for 72 hours in culture; RNAi was induced in cells by the addition of 1 microgram/ml of tetracycline
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Project description:Base J, β-D-glucosyl-hydroxymethyluracil, is an epigenetic modification of thymine in the nuclear DNA of flagellated protozoa of the order Kinetoplastida. J is enriched at sites involved in RNA Polymerase (RNAP) II initiation and termination. We have previously demonstrated a role of J in regulating RNAP II initiation in Trypanosoma cruzi. Reduction of J in Leishmania tarentolae via growth in BrdU resulted in cell death and indicated a role of J in the regulation of RNAP II termination. To further explore J function in RNAP II termination among kinetoplastids and avoid indirect effects associated with BrdU toxicity and genetic deletions, we inhibited J synthesis in L. major and T. brucei using DMOG. Reduction of J in L. major resulted in genome-wide defects in transcription termination and the generation of antisense RNAs, without cell death. In contrast, loss of J in T. brucei did not lead to genome-wide termination defects; however, the loss of J at specific sites within polycistronic gene clusters led to altered transcription elongation and increased expression of downstream genes. Thus, J regulation of transcription termination genome-wide is restricted to Leishmania spp., while in T. brucei it regulates RNAP II elongation and gene expression at specific genomic loci. We studied the effect of loss of base J on transcription using WT and WT cells grown in DMOG-containing medium. We used 2 RNA-seq libraries containing processed RNA products and 4 small RNA libraries representing the entire transcriptome.
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Project description:Trypanosomes have seven cullin paralogs, the majority lineage-specific. Six of those cullins (TbCul-A, TbCul-C, TbCul-D TbCul-E, TbCul-F and TbCul-G) were endogenously 3xHA-epitope tagged at the C-terminus. We used affinity capture/mass spectrometry to determine the composition of these cullin complexes. TbCul-A and TbCul-E function were further studied by analysis of proteome changes upon upon RNAi.
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Project description:RNA polymerase III (RNAP III) synthetizes small essential non-coding RNA molecules such as tRNAs and 5S rRNA. In yeast and vertebrates, RNAP III needs general transcription factors TFIIIA, TFIIIB and TFIIIC to initiate transcription. TFIIIC, composed of six subunits, binds to internal promoter elements in RNAP III-dependent genes. Limited information is available about RNAP III transcription in the trypanosomatid protozoa Trypanosoma brucei and Leishmania major, which diverged early from the eukaryotic lineage. Analyses of the first draft of the trypanosomatid genome sequences failed to recognize orthologs of any of the TFIIIC subunits, suggesting that this transcription factor is absent in these parasites. However, a single putative TFIIIC subunit was recently annotated in the databases. Here we characterize this subunit in T. brucei and L. major and demonstrate that it corresponds to Tau95. In silico analyses showed that both proteins possess the typical Tau95 sequences: the DNA binding region and the dimerization domain. As anticipated for a transcription factor, Tau95 localized to the nucleus in insect forms of both parasites. Chromatin immunoprecipitation (ChIP) assays demonstrated that Tau95 binds to tRNA and U2 snRNA genes in T. brucei. Remarkably, by performing tandem affinity purifications we identified orthologs of TFIIIC subunits Tau55, Tau131 and Tau138 in T. brucei and L. major. Thus, contrary to what was assumed, trypanosomatid parasites do possess a TFIIIC complex. Other putative interacting partners of Tau95 were identified in T. brucei and L. major.
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