Project description:This SuperSeries is composed of the following subset Series:; GSE11940: Topoisomerase II inhibition involves characteristic chromosomal expression patterns: Doxorubicin study; GSE11941: Topoisomerase II inhibition involves characteristic chromosomal expression patterns: Trovafloxacin study Experiment Overall Design: Refer to individual Series
Project description:One major class of anti-cancer drugs targets topoisomerase II to induce DNA double-strand breaks and cell death of fast growing cells. Here, we compare three members of this class - the antracyclines doxorubicin and aclarubicin, and a chemically unrelated compound, etoposide. Aclarubicin does not induce DNA breaks. We define a new activity for the antracyclines: unsupported histone eviction from ´open´ or loosely packed chromosomal areas reflecting exon and promoter regions. Comparison of histone H3K4me3 of cells post topoisomerase II inhibitors treatment to un-treated ones by ChIP-seq. Comparison of phosphorylated histone H2AX of cells post topoisomerase II inhibitors doxorubicin and etoposide treatment to un-treated ones by ChIP-seq.
Project description:The twin supercoiled domain model posits that, as RNA Polymerase II (Pol II) transcribes a gene, it generates negative and positive supercoils upstream and downstream respectively, but little is known about the functional consequence in vivo of the resulting torsional strain. Here we provide a method for high resolution mapping of DNA supercoils using next-generation sequencing, and show that the level of supercoiling is correlated with gene expression in Drosophila cells. Inhibition of topoisomerases, enzymes that relieve torsional strain, leads to accumulation of supercoils surrounding gene bodies and of Pol II at the transcription start sites. Topoisomerase I inhibition results in increased nascent RNA transcripts with Topoisomerase II inhibition shows little change in nascent RNA levels. Despite these different effects on transcription, inhibition of either enzyme results in increased nucleosome turnover within gene bodies, suggesting that torsional stress contributes to destabilizing nucleosomes ahead of Pol II.
Project description:The twin supercoiled domain model posits that, as RNA Polymerase II (Pol II) transcribes a gene, it generates negative and positive supercoils upstream and downstream respectively, but little is known about the functional consequence in vivo of the resulting torsional strain. Here we provide a method for high resolution mapping of DNA supercoils using next-generation sequencing, and show that the level of supercoiling is correlated with gene expression in Drosophila cells. Inhibition of topoisomerases, enzymes that relieve torsional strain, leads to accumulation of supercoils surrounding gene bodies and of Pol II at the transcription start sites. Topoisomerase I inhibition results in increased nascent RNA transcripts with Topoisomerase II inhibition shows little change in nascent RNA levels. Despite these different effects on transcription, inhibition of either enzyme results in increased nucleosome turnover within gene bodies, suggesting that torsional stress contributes to destabilizing nucleosomes ahead of Pol II. 12 paired-end samples and 8 single-end samples were sequenced and analyzed.
Project description:We have previously shown that RNA polymerase II (Pol II) pause release and transcriptional elongation involve phosphorylation of the factor TRIM28 by the DNA damage response (DDR) kinases ATM and DNA-PK. Here, we report a significant role for DNA breaks and DDR signaling in the mechanisms of transcriptional elongation in stimulus-inducible genes in humans. Our data show the enrichment of TRIM28 and γH2AX on serum-induced genes and the important function of DNA-PK for Pol II pause release and transcriptional activation-coupled DDR signaling on these genes. γH2AX accumulation decreases when P-TEFb is inhibited, confirming that DDR signaling results from transcriptional elongation. In addition, transcriptional elongation-coupled DDR signaling involves topoisomerase II because inhibiting this enzyme interferes with Pol II pause release and γH2AX accumulation. Our findings propose that DDR signaling is required for effective Pol II pause release and transcriptional elongation through a novel mechanism involving TRIM28, DNA-PK, and topoisomerase II 42 samples in total. IP targets were gammaH2ax, s2-pol-II, pol-II, pTRIM28, DNA-pk, topo-IIB. Experimental conditions included DMSO treatment (control), pTEFb, topoII-i, dnapk-i. Matched non-specific IP samples used for control in peak calling.
Project description:Topoisomerases are essential for resolving topological problems in the genome, while their function in gene regulation, especially during cellular differentiation, remains unknown. We reveal that the expression of two Topo II isoforms, Top2a and Top2ß, is characteristic of dividing and postmitotic tissues, respectively. In embryonic stem cells, Top2a preferentially binds to promoters embedded in an active chromatin environment. Inhibition of Top2a activity results in misregulation of target gene expression that accompanies accumulation of double-strand breaks. Common targets of Top2a and Top2ß are housekeeping genes while their unique targets are involved in proliferation/pluripotency and neurogenesis, respectively. Moreover, a subset of Top2a targets exhibit bivalent chromatin state that is resolved upon differentiation concomitant with their activation and occupancy by Top2ß, a feature further observed for long genes. These findings suggest that Top2a not only contributes to stem cell transcriptome regulation but may also prime developmental genes for subsequent activation upon differentiation. mRNA profiles of DMSO and ICRF-193 treated mESCs were generated by deep sequencing in triplicates. ICRF-193 is a well established catalytic inhibitor of Topoisomerase II, hence, we used ICRF-193 to the elucidate role of Top2a catalytic activity on transcription by genome wide transcription profiling.
Project description:A major class of chemotherapeutics targets topoisomerase II for DNA double-strand breaks and cancer cell elimination. We compare four members of this class?the anthracyclines doxorubicin, daunorubicin and aclarubicin that does not induce DNA breaks?and a different compound, etoposide. We define a novel activity for anthracyclines: histone eviction from open chromosomal areas. Since histone variant H2AX is also evicted, DNA damage response is attenuated when compared to etoposide. Histone eviction also affects the epigenetic code and deregulates the transcriptome in cancer cells and organs such as the heart. Histone eviction by anthracyclines can drive apoptosis of topoisomerase-negative acute myeloid leukemia blasts in patients. Doxo- and daunorubicin combine the activities of two anti-cancer drugs: etoposide for DNA damage and aclarubicin for histone eviction. We define a novel mechanism of action of anti-cancer drugs doxo- and daunorubicin on chromatin biology with profound consequences on DNA damage responses, epigenetics, transcription, side effects and anti-cancer activities. Comparison of histone occupancy of cells or tissues treated with topoisomerase II inhibitors to un-treated ones by FAIRE-seq.
Project description:We have previously shown that RNA polymerase II (Pol II) pause release and transcriptional elongation involve phosphorylation of the factor TRIM28 by the DNA damage response (DDR) kinases ATM and DNA-PK. Here, we report a significant role for DNA breaks and DDR signaling in the mechanisms of transcriptional elongation in stimulus-inducible genes in humans. Our data show the enrichment of TRIM28 and γH2AX on serum-induced genes and the important function of DNA-PK for Pol II pause release and transcriptional activation-coupled DDR signaling on these genes. γH2AX accumulation decreases when P-TEFb is inhibited, confirming that DDR signaling results from transcriptional elongation. In addition, transcriptional elongation-coupled DDR signaling involves topoisomerase II because inhibiting this enzyme interferes with Pol II pause release and γH2AX accumulation. Our findings propose that DDR signaling is required for effective Pol II pause release and transcriptional elongation through a novel mechanism involving TRIM28, DNA-PK, and topoisomerase II