Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA308572 | ENA |
REPOSITORIES: ENA
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Project description:Topoisomerase 1 (Top1) removes supercoils from DNA during replication and transcription, is critical for mitotic progression to the G1 phase, and ensures DNA topology. Tyrosyl-DNA phosphodiesterase 1 (TDP1) mediates the removal of trapped Top1-DNA covalent complexes (Top1ccs). Here, we identify CDK1-dependent phosphorylation of TDP1 at S61 residue during mitosis. TDP1 defective for S61 phosphorylation (TDP1S61A) is trapped on the mitotic chromosomes, triggering DNA damage and mitotic defects. Moreover, we show that Top1cc repair in mitosis occurs via MUS81-dependent mitotic DNA repair mechanism. Replication stress (RS) induced by Camptothecin (CPT) or Aphidicolin (APH) leads to TDP1S61A enrichment at common fragile sites (CFSs), which over-stimulates MUS81-dependent chromatid breaks, anaphase bridges, and micronuclei, ultimately culminating in 53BP1 nuclear bodies in the G1-phase. Our findings provide a new insight into the cell cycle-dependent regulation of TDP1 dynamics forthe repair of trapped Top1ccs during mitosis that prevents genomic instability following RS.
2024-06-26 | PXD053309 | Pride
Project description:Genomic instability is frequently caused by nucleic acids structures formed during transcription termed R-loops. Despite their harmful potential, mechanisms that sense, signal and suppress these structures remain elusive. Here we report that oscillations in transcription dynamics are a major sensor of R-loops. We show that pausing of RNA polymerase II (RNA Pol II) initiates a signaling cascade whereby the serine/arginine protein kinase 2 (SRPK2) phosphorylates the DDX23 helicase culminating in the suppression of R-loops. We show that in the absence of either SRPK2 or DDX23, accumulation of R-loops leads to massive genomic instability revealed by high levels of DNA double-strand breaks (DSBs). Importantly, we found DDX23 mutations in several cancers and detected homozygous deletions of the entire DDX23 locus in 10 (17%) adenoid cystic carcinoma samples. Our results unravel molecular details of a novel link between transcription dynamics and RNA-mediated genomic instability that may play important roles in cancer development.
2016-12-22 | GSE76777 | GEO
Project description:Nuclear myosin 1c (NM1) mediates RNA polymerase I (pol I) transcription activation and cell cycle progression by facilitating PCAF-mediated H3K9 acetylation, but the molecular mechanism by which NM1 is regulated remains unclear. Here, we report that at early G1 the glycogen synthase kinase (GSK) 3β phosphorylates and stabilizes NM1, allowing for NM1 association with the chromatin. Genomic analysis by ChIP-Seq showed that this mechanism occurs on the rDNA as active GSK3β selectively occupies the gene. ChIP assays and transmission electron microscopy in GSK3β-/- mouse embryonic fibroblasts indicated that at G1 rRNA synthesis is suppressed due to decreased H3K9 acetylation leading to a chromatin state incompatible with transcription. We found that GSK3β directly phosphorylates the endogenous NM1 on a single serine residue (Ser-1020) located within the NM1 C-terminus. In G1 this phosphorylation event stabilizes NM1 and prevents NM1 polyubiquitination by the E3 ligase UBR5 and proteasome-mediated degradation. We conclude that GSK3β-mediated phosphorylation of NM1 is required for pol I transcription activation. Examination of GSK3beta with the genome in mouse embryonic fibroblasts
2014-05-02 | E-GEOD-57153 | biostudies-arrayexpress
Project description:R-loops are formed when replicative forks collide with the transcriptional machinery and can cause genomic instability. However, it is unclear how R-loops are regulated at transcription-replication conflicts (TRC) sites and how replisome proteins are regulated to prevent R-loop formation or mediate R-loop tolerance. Here, we report that ATAD5, a PCNA unloader, plays dual functions to reduce R-loops both under normal and replication stress conditions. ATAD5 interacts with RNA helicases such as DDX1, DDX5, DDX21 and DHX9 and increases the abundance of these helicases at replication forks to facilitate R-loop resolution. Depletion of ATAD5 or RNA helicases consistently increases R-loops during the S phase and reduces the replication rate, both of which are enhanced by replication stress. In addition to R-loop resolution, ATAD5 prevents the generation of new R-loops behind the replication forks by unloading PCNA which, otherwise, accumulates and persists on DNA, causing a collision with the transcription machinery. Depletion of ATAD5 reduces transcription rates due to PCNA accumulation. Consistent with the role of ATAD5 and RNA helicases in maintaining genomic integrity by regulating R-loops, the corresponding genes were mutated or downregulated in several human tumors.
2021-09-09 | PXD018207 | Pride
Project description:Aberrant (pro)renin receptor expression induces genomic instability in pancreatic ductal adenocarcinoma through upregulation of SMARCA5/SNF2H
2020-12-15 | PXD010107 | JPOST Repository
Project description:The RNA polymerase II carboxy-terminal domain (CTD) consists of conserved repeats of the consensus sequence Y1-S2-P3-T4-S5-P6-S7, which can be phosphorylated to influence distinct stages of the transcription cycle, including RNA processing. Although affinity purification coupled with mass spectrometry has defined CTD-associated proteins, phospho-dependent CTD interactions have remained largely elusive. Proximity-dependent biotinylation (PDB) provides an alternative approach to identify protein-protein associations in the native cellular environment. Here we present a PDB-based map of the fission yeast RNAPII CTD in live cells. The proteomic screen identified known CTD-associated proteins, but also captured new and unexpected CTD proximal proteins. We also used PDB to identify phospho-dependent CTD interactions by using a mutant in which Ser2 was replaced by alanine in every repeat of the fission yeast CTD. Surprisingly, CTD-mediated biotinylation of most 3’ end processing factors was not affected in the S2A mutant, consistent with RNA-seq and ChIP-seq analysis indicating that CTD Ser2 phosphorylation is not required for 3’ end processing and transcription termination. Conversely, we found that CTD Ser2 phosphorylation is critical for the association between RNAPII and the histone methyltransferase Set2 during transcription elongation. We show that loss of CTD Ser2 phosphorylation disables the Set2-Clr6(II) axis, resulting in a global increase in cryptic antisense transcription that correlates with elevated levels of histone acetylation in gene bodies. Our findings reveal that the fundamental role of CTD Ser2 phosphorylation is to establish a chromatin-based repressive state that prevents cryptic intragenic transcription initiation.
2024-05-06 | PXD047023 | Pride
Project description:Topoisomerase I (Top1) is a key enzyme acting at the interface between DNA replication, transcription and mRNA maturation. Here, we show that Top1 suppresses genomic instability in mammalian cells by preventing conflicts between transcription and DNA replication. Using DNA combing and ChIP-on-chip, we found that Top1-deficient cells accumulate stalled replication forks and chromosome breaks in S phase and that breaks occur preferentially at gene-rich regions of the genome. Strikingly, these phenotypes were suppressed by preventing the formation of RNA-DNA hybrids (R-loops) during transcription. Moreover, these defects could be mimicked by depletion of the splicing factor ASF/SF2, which interacts functionally with Top1. Taken together, these data indicate that Top1 prevents replication fork collapse by suppressing the formation of R-loops in an ASF/SF2-dependent manner. We propose that interference between replication and transcription represents a major source of spontaneous replication stress, which could drive genomic instability during early stages of tumorigenesis. Bed files contain the gamma-H2AX enrichment sites described in the paper
2009-08-08 | GSE17552 | GEO
Project description:Deletion of ssu72 gene leads to a transcription elongation defect and the increase in the level of Ser5 and Ser7 phosphorylation in CTD of Rpb1 Phosphorylation of the RNA polymerase II C-terminal domain on heptad Y1S2P3T4S5P6S7 coordinates key events during transcription and when its deregulation leads to defects in transcription and RNA processing. Here we report that histone deacetylase complex activity of the fission yeast Hos2/Set3 complex plays an important role in suppressing cryptic initiation of the antisense transcription when the C-terminal domain phosphorylation is dysregulated due to the loss of Ssu72 phosphatase. Interestingly, while single hos2/set3 mutants have little effect, loss of hos2 or set3 in addition to ssu72? leads to synergistic increase in antisense transcription globally and correlates with increases genomic instability and formation of deleterious R-loop structures across these regions. We propose that Ssu72 is essential to suppress initiation of cryptic transcription in the 3?end of the RNA polymerase II transcribed regions. In the absence of Ssu72, antisense transcription is supressed by the Hos2/Set3 dependent surveillance mechanism to maintain genome stability.
2020-06-30 | GSE144594 | GEO
Project description:Casein Kinase 2 Mediated Phosphorylation of Spt6 Modulates Histone dynamics and Regulates Spurious Transcription (RNA-Seq)
| PRJNA427393 | ENA
Project description:Nuclear myosin 1c (NM1) mediates RNA polymerase I (pol I) transcription activation and cell cycle progression by facilitating PCAF-mediated H3K9 acetylation, but the molecular mechanism by which NM1 is regulated remains unclear. Here, we report that at early G1 the glycogen synthase kinase (GSK) 3β phosphorylates and stabilizes NM1, allowing for NM1 association with the chromatin. Genomic analysis by ChIP-Seq showed that this mechanism occurs on the rDNA as active GSK3β selectively occupies the gene. ChIP assays and transmission electron microscopy in GSK3β-/- mouse embryonic fibroblasts indicated that at G1 rRNA synthesis is suppressed due to decreased H3K9 acetylation leading to a chromatin state incompatible with transcription. We found that GSK3β directly phosphorylates the endogenous NM1 on a single serine residue (Ser-1020) located within the NM1 C-terminus. In G1 this phosphorylation event stabilizes NM1 and prevents NM1 polyubiquitination by the E3 ligase UBR5 and proteasome-mediated degradation. We conclude that GSK3β-mediated phosphorylation of NM1 is required for pol I transcription activation.
2014-05-02 | GSE57153 | GEO