Histone variant 3 regulates RNA polymerase II transcription termination and dual strand transcription of siRNA loci in Trypanosoma brucei
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ABSTRACT:
ORGANISM(S): Trypanosoma brucei
SUBMITTER: David Reynolds
PROVIDER: E-GEOD-70229 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
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.
2015-05-18 | E-GEOD-57621 | biostudies-arrayexpress
Project description:Base J and H3.V promote RNA Polymerase (RNAP) II termination within polycistronic gene clusters in the kinetoplastid species Trypanosoma brucei. Although base J has been shown to promote RNAP II termination in the related kinetoplastid species Leishmania major and Leishmania tarentolae, the role of H3.V was unclear. The effect of acute J loss on mRNA transcript abundance was also unknown. We find here that H3.V does not promote transcription termination in Leishmania major, but loss of H3.V does reduce J levels. The J loss in H3.V knockout cells is not enough to result in a termination defect, which we show is due to a threshold level of J that is sufficient to promote termination. Loss of J beyond that threshold results in termination defects. Further, the decreased J in H3.V knockout cells allowed greater reduction of J by dimethyloxalylglycine (DMOG), which inhibits J synthesis, compared to wild type cells treated with DMOG, and resulted in stronger defects in RNAP II termination and cell growth. By mRNA-seq we see largely upregulation of genes near the ends of gene clusters following J loss, indicating that J represses genes near termination sites. These findings reveal a conserved role of J in promoting termination prior to the end of polycistronic gene clusters in kinetoplastid parasites and suggest that the essential nature of J is related to its role in repressing genes by promoting termination. The role of base J and H3.V in promoting RNA Polymerase II transcription termination was assessed by small RNA-seq, mRNA-seq, and strand-specific RT-PCR. Wild type cells were compared to H3.V knockout cells and to WT and H3.V knockout cells treated with dimethyloxalylglycine (DMOG) to reduce base J.
2016-07-20 | E-GEOD-77632 | biostudies-arrayexpress
Project description:Trypanosoma brucei spp. develop into mammalian-infectious metacyclic trypomastigotes inside tsetse salivary glands. Besides acquiring a variant surface glycoprotein (VSG) coat, little is known about the metacyclic expression of invariant surface antigens. Proteomics analyses of saliva from T. brucei-infected flies identified, in addition to VSG and Brucei Alanine-Rich Protein (BARP) peptides, a family of GPIanchored surface proteins herein named Metacyclic Invariant Surface Proteins (MISP). The MISP family is encoded by five paralog genes with >80% protein identity, which are exclusively expressed by salivary gland stages of the parasite and peak in metacyclic stage, as shown by confocal microscopy and immuno-high resolution scanning electron microscopy. Crystallographic analysis of a MISP isoform (MISP360) and a high confidence model of BARP revealed a triple helical bundle architecture commonly found in other trypanosome surface proteins. Molecular modelling combined with live fluorescent microscopy suggests that MISP N-termini are extended above the VSG coat. However, vaccination with recombinant MISP360 isoform did not protect mice against a T. brucei infectious tsetse bite. Lastly, both RNAi knock down and CRISPR-Cas9-driven knock out of all MISP paralogues suggest they are not essential for parasite development in the tsetse vector. We speculate that MISP may be relevant during trypanosome inoculation or establishment in the vertebrate’s skin.
2023-05-10 | PXD039684 | Pride
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance Bloodstream stages of the Lister strain 427 T. b. brucei (MiTat 1.2), expressing VSG221, were used in these studies. Cells were cultured in HMI-9 medium with the addition of heat inactivated fetal bovine serum (FBS) (10%) and Serum Plus (10%). T. b. brucei 427-221 is an antigenically stable line and contains a single copy of the vsg221 gene within the 221 expression site (221ES). At a cell density of approximately 1,000,000 cells/ml, T. b. brucei 427-221 were exposed to various amounts of human HDLs for 24 h in a 6 well plate. Surviving trypanosomes were counted using a hemocytometer then diluted into fresh HMI-9 medium and allowed to recover for 5-14 days. Once the cells had grown to a density of approximately 1,000,000 cells/ml, they were once again incubated with human HDLs. Each round of selection was performed with increasing concentrations of human HDLs and freezer stocks were prepared for each surviving population. Over nine months we conducted eight rounds of human HDL selection, resulting in a population of T. b. brucei that survived incubation with 800 μl of human HDLs (160 lytic U).
2007-07-04 | E-GEOD-8369 | biostudies-arrayexpress
Project description:Histone variant 3 (H3V) is a kinetoplastid specific histone variant that is enriched at RNA polymerase II termination sites and telomeres. We previously found that the DNA modification base J, which co-localizes with H3V, functions to prevent readthrough transcription within gene clusters in T. brucei. We now demonstrate a similar role for H3V, where the loss of this histone variant results in increased expression of downstream genes. The effect is larger when both H3V and J are lost. Additionally, removal of H3V results in increased siRNAs from dual strand transcribed loci as well as increased expression of silent VSGs, indicating a role of H3V in the regulation of antigenic variation
2016-06-30 | GSE70229 | GEO
Project description:Histone variant 3 (H3V) is a kinetoplastid specific histone variant that is enriched at RNA polymerase II termination sites and telomeres. We previously found that the DNA modification base J, which co-localizes with H3V, functions to prevent readthrough transcription within gene clusters in T. brucei. We now demonstrate a similar role for H3V, where the loss of this histone variant results in increased expression of downstream genes. The effect is larger when both H3V and J are lost. Additionally, removal of H3V results in increased siRNAs from dual strand transcribed loci as well as increased expression of silent VSGs, indicating a role of H3V in the regulation of antigenic variation
2016-01-25 | GSE69929 | GEO
Project description:Trypanosoma brucei subspecies infect humans and animals in sub-Saharan Africa. This early diverging eukaryote shows many novel features in basic biological processes, including the use of polycistronic transcription to generate all protein-coding mRNAs. Therefore we hypothesized that translational control provides a means to tune gene expression during parasite development in mammalian and fly hosts. We used ribosome profiling to examine genome-wide protein production in animal-derived slender bloodstream forms and cultured procyclic (insect midgut) forms. About one-third of all CDSs showed statistically significant regulation of protein production between the two stages. Of these, more than two-thirds showed a change in translation efficiency, but few were controlled by this parameter alone. Ribosomal proteins were translated poorly, especially in animal-derived parasites. A disproportionate number of metabolic enzymes were up-regulated at the mRNA level in procyclic forms, as were variant surface glycoproteins in bloodstream forms. Comparison with cultured bloodstream forms from another strain identified stage-specific changes in protein production that transcend strain and growth conditions. Genes with upstream ORFs had a lower mean translation efficiency but no evidence was seen for involvement of these ORFs in stage-regulation. Ribosome profiling revealed that differences in the production of specific proteins in T. brucei slender bloodstream and procyclic forms are more common than anticipated from analysis of mRNA abundance. While in vivo and in vitro derived slender bloodstream forms of different strains are more similar to one another than to procyclic forms, they showed numerous differences at both the mRNA and protein production level. Ribosome profiling and mRNA libraries were constructed in triplicate from in vitro PCF and in vivo BF lifestages of theT. brucei Treu927 and in vitro T. brucei Lister427, to evaluate role of translational gene regulation
2014-05-24 | E-GEOD-57336 | biostudies-arrayexpress
Project description:Protein-coding genes in kinetoplastid protists are transcribed from polycistronic arrays, yielding RNA precursors which are processed to form mature transcripts bearing a 5M-bM-^@M-^Y spliced leader (SL) and 3M-bM-^@M-^Y poly(A) tract. Regions of transcription initiation and termination lack known eukaryotic promoter and terminator elements, and current data suggest that transcription is instead regulated predominantly through epigenetic mechanisms. Several epigenetic marks, including histone modifications, histone variants, and an atypical DNA modification known as base J have been localized to regions of transcription initiation or termination in Trypanosoma brucei, Trypanosoma cruzi, and/or Leishmania major. Despite this conservation, the phenotypes of base J mutants vary significantly across trypanosomatids, suggesting that the specific epigenetic networks governing transcription initiation and termination have diverged significantly during evolution. In this light, we sought to characterize and compare the roles of the histone variants H2A.Z, H2B.V, and H3.V in L. major. As in T. brucei, the histone variants H2A.Z and H2B.V were shown to be essential in L. major using a powerful quantitative plasmid segregation-based test. In contrast and again similar to T. brucei, H3.V is not essential in Leishmania as H3.V-null lines grew normally, resembled WT, and remained infectious. Using SL-primed RNA-seq, we found that H3.V-null parasites have steady-state transcript levels comparable to WT parasites and display no defects in the efficiency of transcription termination at convergent strand switch regions (SSRs). Our results show a conservation of histone variant phenotypes between L. major and T. brucei, in contrast to the phenotypes associated with the epigenetic DNA base J modification. Total RNA from Four LmjF samples were analyzed using RNA-Seq. One of them is wildtype parasites, one is single knockout for H3V gene and two independent double knockouts for H3V gene.
2013-10-26 | E-GEOD-51737 | biostudies-arrayexpress
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.
2015-05-18 | GSE57621 | GEO
Project description:T. brucei PF cells were treated with several chemical reagents and anti-trypanosomatid drugs. The effect of each chemical perturbation on the transcriptome of T. brucei was examined by transcript profiling of treated vs. control cells. The results indicated widespread changes, suggesting that the transcriptome of T. brucei is highly responsive to environmental factors that perturb its metabolic and biological pathways. 11 chemical perturbations, each co-hybridized with a common reference RNA from control non-treated cells. One array per treatment.
2012-05-29 | E-GEOD-37593 | biostudies-arrayexpress