Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Epigenetic regulation of transcription and virulence of Trypanosoma cruzi

ABSTRACT: Trypanosoma cruzi, a flagellated protozoan, is the causative agent of Chagas’ disease, a chronic and potentially fatal disease that causes irreversible damage to heart and digestive tract in humans. Like all trypanosomes, the protein coding genes of T. cruzi are arranged into large polycistronic gene clusters transcribed by polymerase II (Pol II). Therefore, trypanosomes presumably rely on post-transcriptional process to regulate gene expression. Pol II promoters have not been identified and there is no evidence for regulated gene expression at the transcriptional level. However, the presence of the hyper-modified DNA base J, Beta-D-glucosyl hydroxymethyluracil, at regions flanking the polycistronic units (PTU) in T. brucei suggested its involvement in regulating Pol II transcription. We now demonstrate that base J is localized at PTU flanking regions in T. cruzi and levels are differentially regulated by the thymidine hydroxylases, JBP1 and JBP2, involved in J biosynthesis. Microarray analysis of the JBP1dKO and JBP2dKO indicate the up and down regulation of several hundred genes distributed throughout the genome. We show a large increase in Pol II transcription rate following the decrease in base J at the PTU flanks. Changes in gene expression include virulence genes and parasites are defective in host cell invasion and egress. There is a direct correlation between the reduction in base J levels, number of genes affected and strength of the virulence phenotype. These studies indicate that base J represents an epigenetic factor regulating Pol II transcription initiation in kinetoplastids and provides a biological role of the only hyper-modified DNA base in eukaryotes.

ORGANISM(S): Trypanosoma cruzi

PROVIDER: GSE23855 | GEO | 2011/01/01

SECONDARY ACCESSION(S): PRJNA130629

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

Epigenetic regulation of transcription and virulence of Trypanosoma cruzi

Project description:Trypanosoma cruzi, a flagellated protozoan, is the causative agent of Chagas’ disease, a chronic and potentially fatal disease that causes irreversible damage to heart and digestive tract in humans. Like all trypanosomes, the protein coding genes of T. cruzi are arranged into large polycistronic gene clusters transcribed by polymerase II (Pol II). Therefore, trypanosomes presumably rely on post-transcriptional process to regulate gene expression. Pol II promoters have not been identified and there is no evidence for regulated gene expression at the transcriptional level. However, the presence of the hyper-modified DNA base J, Beta-D-glucosyl hydroxymethyluracil, at regions flanking the polycistronic units (PTU) in T. brucei suggested its involvement in regulating Pol II transcription. We now demonstrate that base J is localized at PTU flanking regions in T. cruzi and levels are differentially regulated by the thymidine hydroxylases, JBP1 and JBP2, involved in J biosynthesis. Microarray analysis of the JBP1dKO and JBP2dKO indicate the up and down regulation of several hundred genes distributed throughout the genome. We show a large increase in Pol II transcription rate following the decrease in base J at the PTU flanks. Changes in gene expression include virulence genes and parasites are defective in host cell invasion and egress. There is a direct correlation between the reduction in base J levels, number of genes affected and strength of the virulence phenotype. These studies indicate that base J represents an epigenetic factor regulating Pol II transcription initiation in kinetoplastids and provides a biological role of the only hyper-modified DNA base in eukaryotes. J1 and J2 null mutant trypomastigotes were each compared to wild type trypomastigotes. There were 3 biological replicates for each comparison.

2011-01-01 | E-GEOD-23855 | biostudies-arrayexpress

Epigenetic regulation of transcription and virulence in Trypanosoma cruzi by O-linked thymine glucosylation of DNA

Project description:Unlike other eukaryotes, the protein coding genes of Trypanosoma cruzi are arranged into large polycistronic gene clusters transcribed by polymerase II (Pol II). Thus, trypanosomes rely on post-transcriptional processes to regulate gene expression. Here, we show that the glucosylated thymine DNA base (-D-glucosyl hydroxymethyluracil or base J) is present within sequences flanking the polycistronic units (PTU) in T. cruzi. loss of base J at sites of transcription initiation, via deletion of the two enzymes that regulate J synthesis (JBP1 and JBP2), correlates with an increased rate of Pol II transcription and subsequent genome-wide increase in gene expression. genes include virulence genes and the resulting parasites are defective in host cell invasion and egress. These studies indicate that base J represents an epigenetic factor regulating Pol II transcription initiation in kinetoplastids, and provides the first biological role of the only hyper-modified DNA base in eukaryotes. This entry contains the results using SLT, digital gene expression profiling of tags read off the spliced leader sequence of all mature trypanosomatid messages, for the life-cycle of T. cruzi, four stages, in wild-type as well as JBP1 KO cells.

2011-01-21 | GSE26754 | GEO

Identification of sequence-specific promoters driving polycistronic transcription initiation by RNA Polymerase II in trypanosomes

Project description:Protein coding genes in the trypanosome genome are organized in polycistronic transcription units (PTUs). How RNA Polymerase II (Pol II) initiates PTU transcription has not been resolved and the current model favors initiation driven by chromatin epigenetic marks, rather than core-promoters. Here, we identify sequence-specific core promoters by functional characterization of ChIP-Seq Pol II accumulation-peaks. Sequences located between oppositely orientated PTUs contained two independent and distinct core promoters, driving unidirectional transcription. Detailed analysis of one promoter identified 75 bp, necessary and sufficient to fully drive reporter expression, and containing short functional motifs. Analysis of further promoters suggested activity and initiation is regulated and both, focused and dispersed transcription patterns were found. Thus, in contrast to the model of unregulated and promoter-independent transcription initiation, sequence-specific promoters determine the initiation of RNA Pol II transcription of protein coding genes in trypanosomes. These findings resolve the discrepancy between trypanosomes and other eukaryotes in how Pol II initiates protein-coding gene transcription.

2021-02-01 | GSE130798 | GEO

Regulation of Transcription Termination by Glucosylated Hydroxymethyluracil, Base J, in L. major and T. brucei

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

A novel SNF2 ATPase complex in Trypanosoma brucei with a role in H2A.Z-mediated chromatin remodelling

Project description:A cascade of histone acetylation events with subsequent incorporation of a histone H2A variant plays an essential part in transcription regulation in various model organisms. A key player in this cascade is the chromatin remodellling complex SWR1, which replaces the canonical histone H2A with its variant H2A.Z. Transcriptional regulation of polycistronic transcription units in the unicellular parasite Trypanosoma brucei has been shown to be highly dependent on acetylation of H2A.Z, which is mediated by the histone-acetyltransferase HAT2. The chromatin remodellling complex, which mediates H2A.Z incorporation is not known and an SWR1 orthologue in trypanosomes has not yet been reported. In this study, we identified and characterised an SWR1-like remodelller complex in T. brucei that is responsible for Pol II-dependent transcriptional regulation. Bioinformatic analysis of potential SNF2 DEAD/Box helicases, the key component of SWR1 complexes, identified a 1211 amino acids-long protein that exhibits key structural characteristics of the SWR1 subfamily. Systematic protein-protein interaction analysis revealed the existence of a novel complex exhibiting key features of an SWR1-like chromatin remodelller. RNAi-mediated depletion of the ATPase subunit of this complex resulted in a significant reduction of H2A.Z incorporation at transcription start sites and a subsequent decrease of steady-state mRNA levels. Furthermore, depletion of SWR1 and RNA-polymerase II (Pol II) caused massive chromatin condensation. The potential function of several proteins associated with the SWR1-like complex and with HAT2, the key factor of H2A.Z incorporation, is discussed.

2022-08-12 | PXD026796 | Pride

Relationship between nucleosome positioning and DNA methylation: ChIP-chip

Project description:Nucleosomes compact and regulate access to DNA in the nucleus, and are composed of approximately 147 bases of DNA wrapped around a histone octamer1, 2. Here we report a genome-wide nucleosome positioning analysis of Arabidopsis thaliana utilizing massively parallel sequencing of mononucleosomes. By combining this data with profiles of DNA methylation at single base resolution, we identified ten base periodicities in the DNA methylation status of nucleosome-bound DNA and found that nucleosomal DNA was more highly methylated than flanking DNA. These results suggest that nucleosome positioning strongly influences DNA methylation patterning throughout the genome and that DNA methyltransferases preferentially target nucleosome-bound DNA. We also observed similar trends in human nucleosomal DNA suggesting that the relationships between nucleosomes and DNA methyltransferases are conserved. Finally, as has been observed in animals, nucleosomes were highly enriched on exons, and preferentially positioned at intron-exon and exon-intron boundaries. RNA Pol II was also enriched on exons relative to introns, consistent with the hypothesis that nucleosome positioning regulates Pol II processivity. We also found that DNA methylation enriched on exons, consistent with the targeting of DNA methylation to nucleosomes. Genomic DNA associated with RNAP II was isolated by ChIP using an anti-PolII antibody.

2010-05-28 | E-GEOD-21818 | biostudies-arrayexpress

RPAP2 regulates a transcription initiation checkpoint by prohibiting assembly of preinitiation complex [ChIP-seq]

Project description:RNA polymerase II (Pol II)-mediated transcription in metazoan requires precise regulation. RNA polymerase II-associated protein 2 (RPAP2) was previously identified to transport Pol II from cytoplasm to nucleus and dephosphorylates Pol II C-terminal domain (CTD). We found that RPAP2 binds hypo/hyper-phosphorylated Pol II with undetectable phosphatase activity. Structure of RPAP2-Pol II shows mutually exclusive assembly of RPAP2-Pol II and pre-initiation complex (PIC) due to three steric clashes. RPAP2 prevents/disrupts Pol II-TFIIF interaction and impairs in vitro transcription initiation, suggesting a function in prohibiting PIC assembly. Loss of RPAP2 in cells leads to global accumulation of TFIIF and Pol II at promoters, indicating critical role of RPAP2 in inhibiting PIC assembly independent of its putative phosphatase activity. Our study indicates that RPAP2 functions as a gatekeeper to prohibit PIC assembly and transcription initiation and suggests a novel transcription checkpoint.

2022-05-04 | GSE193679 | GEO

RPAP2 regulates a transcription initiation checkpoint by prohibiting assembly of preinitiation complex [ChIP-Rx]

2022-05-04 | GSE193678 | GEO

RPAP2 regulates a transcription initiation checkpoint by prohibiting assembly of preinitiation complex [TT-seq]

2022-05-04 | GSE192782 | GEO

Regulation of Transcription Termination by Glucosylated Hydroxymethyluracil, Base J, in L. major and T. brucei

2015-05-18 | GSE57621 | GEO