Intragenomic ribosomal DNA variation in gymnosperms
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REPOSITORIES: ENA
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Project description:Ribosomal DNA (rDNA) arrays are highly repetitive regions of the genome which encode essential genes required to produce ribosomes. DNA double-stranded breaks (DSBs) generated within rDNA genes elicit a unique cellular response involving robust transcriptional silencing and nucleolar reorganization into ‘cap’ structures at the nucleolar periphery. This process is coordinated by the nucleolar scaffolding protein TCOF1, which functions to recruit the DNA repair proteins NBS1 and TOPBP1 that activate the ATM and ATR kinases, resulting in ribosomal RNA (rRNA) transcriptional silencing and nucleolar segregation. However, the DNA damage and repair response at rDNA arrays remains incompletely understood. Here, we investigate the cellular response to rDNA DSBs using proteomics and genetic CRISPR-Cas9 screening. We show that the protein UFMylation pathway and the HUSH complex are important for cell viability and survival in response to rDNA DSBs, and that the E3 UFM1-ligase UFL1 and its heterodimer DDRGK1 are associated with TCOF1 at nucleolar caps. Loss of UFL1 leads to impaired ATM activation, reduced rRNA transcriptional silencing, and an overall reduction in nucleolar segregation. We identified ATM, UNC45A and SMC6 as UFMylated proteins, in which UFMylation may facilitate ATM activation and segregation of damaged rDNA to the nucleolar periphery. Altogether, our findings provide the first evidence for a role for UFMylation in rDNA DSB repair.
2024-01-29 | GSE253809 | GEO
Project description:Ribosomal DNA (rDNA) is organized as large arrays of tandem repeats that vary in copy number from a few dozen to hundreds. In the budding yeast Saccharomyces cerevisiae, each rDNA repeat includes a potential origin of replication. Previous work has led to the model that the rDNA replication origins compete for limiting replication initiation factors with origins in the rest of the genome, suggesting that reduction in rDNA copy number would reduce competition for these limiting factors and therefore promote origin usage in the rest of the genome. To test this hypothesis, we compared genome-wide replication in strains with either wild type rDNA copy number of ~180 (“180 rDNA”) or just ~35 copies (“35 rDNA”) by performing dense-to-light isotope transfer experiments to physically separate replicated, hybrid-density (HL or heavy-light) DNA from unreplicated, HH (heavy-heavy) DNA in cell samples collected at different times in S phase. Contrary to our expectations, we find that although there are no apparent differences in non-rDNA origin activity between the two strains, the 35 rDNA strain shows a genome-wide delay in progression through S phase compared to the 180 rDNA strain.
2023-02-17 | GSE205068 | GEO
Project description:Epithelial Cell Transforming Sequence 2 (ECT2), a guanine nucleotide exchange factor (GEF) for Rho GTPases, is overexpressed in many cancers and is involved in signal transduction pathways that promote cancer cell proliferation, invasion and tumorigenesis. Recently, we demonstrated that a significant pool of ECT2 localizes to the nucleolus of non small cell lung cancer (NSCLC) cells where it binds the transcription factor Upstream Binding Factor 1 (UBF1) on the promoter regions of the ribosomal DNA (rDNA) and activates rDNA transcription, transformed growth and tumor formation. Here we investigate the mechanism by which ECT2 engages UBF1 on rDNA. Mutagenesis of ECT2 demonstrates that the tandem BRCT domain of ECT2 mediates binding to UBF1. Biochemical and mass spectrometry analysis reveals that Protein Kinase Ci (PKCi) directly phosphorylates UBF1 at Ser412 to generate a phosphopeptide binding epitope that binds the ECT2 BRCT domain. Lentiviral shRNA knockdown and reconstitution experiments demonstrate that both a functional ECT2 BRCT domain and the UBF1 Ser412 phosphorylation site are required for UBF1 mediated ECT2 recruitment to rDNA, elevated rRNA synthesis and transformed growth. Taken together, our study provides new molecular insight into ECT2 mediated regulation of rDNA transcription in cancer cells and provides a rationale for therapeutic targeting of UBF1 and ECT2 stimulated rDNA transcription for the treatment of NSCLC.
2020-04-10 | MSV000085269 | MassIVE
Project description: Not available
| S-EPMC2292623 | biostudies-literature
Project description:In the present work we have applied analytical methods to map repair events in rDNA using data generated by the newly developed XR-seq genome-wide single nucleotide repair technology. We find that in human and mouse cell lines, rDNA is not subject to TCR of damage caused by UV or by cisplatin.
2018-11-24 | GSE121042 | GEO
Project description:Ribosome is the most abundant RNA-protein complex in a cell and many copies of the ribosomal RNA gene (rDNA) have to be maintained. However, arrays of tandemly repeated rDNA genes can lose the copies by intra-repeat recombination. Loss of the rDNA copies of Saccharomyces cerevisiae is counteracted by gene amplification whereby the number of rDNA repeats stabilizes around 150 copies, suggesting the presence of a monitoring mechanism that counts and adjusts the number. Here, we report that in response to rDNA copy loss, the upstream activating factor (UAF) for RNA polymerase I which transcribes the rDNA is released and directly bind to a RNA polymerase II transcribed gene, SIR2 to repress, whose gene products silence rDNA recombination. We show that the amount of UAF determines rDNA copies number that is stably maintained. UAF ensures rDNA production not only by rDNA transcription activation but also by its copy number maintenance.
2019-01-03 | GSE116661 | GEO
Project description:In S. cerevisiae, replication timing is controlled by epigenetic mechanisms restricting the accessibility of origins to limiting initiation factors. About 30% of these origins are located within repetitive DNA sequences such as the ribosomal DNA (rDNA) array, but their regulation is poorly understood. Here, we have investigated how histone deacetylases (HDACs) control the replication program in budding yeast. This analysis revealed that two HDACs, Rpd3 and Sir2, control replication timing in an opposite manner. Whereas Rpd3 delays initiation at late origins, Sir2 is required for the timely activation of early origins. Moreover, Sir2 represses initiation at rDNA origins whereas Rpd3 counteracts this effect. Remarkably, deletion of SIR2 restored normal replication in rpd3 cells by reactivating rDNA origins. Together, these data indicate that HDACs control the replication timing program in budding yeast by modulating the ability of repeated origins to compete with single-copy origins for limiting initiation factors. MNase-seq analysis of nucleosome position in wt, sir2 and rpd3 cells, aligned against genomic DNA (sacCer3; *sorted_s3.bed) and rDNA sequences (*rdna_nucleosomes.bed)
2014-05-14 | E-GEOD-57618 | biostudies-arrayexpress
Project description:In S. cerevisiae, replication timing is controlled by epigenetic mechanisms restricting the accessibility of origins to limiting initiation factors. About 30% of these origins are located within repetitive DNA sequences such as the ribosomal DNA (rDNA) array, but their regulation is poorly understood. Here, we have investigated how histone deacetylases (HDACs) control the replication program in budding yeast. This analysis revealed that two HDACs, Rpd3 and Sir2, control replication timing in an opposite manner. Whereas Rpd3 delays initiation at late origins, Sir2 is required for the timely activation of early origins. Moreover, Sir2 represses initiation at rDNA origins whereas Rpd3 counteracts this effect. Remarkably, deletion of SIR2 restored normal replication in rpd3 cells by reactivating rDNA origins. Together, these data indicate that HDACs control the replication timing program in budding yeast by modulating the ability of repeated origins to compete with single-copy origins for limiting initiation factors. BrdU-IP-chip analysis of origin usage in different yeast HDAC mutants
2014-03-26 | E-GEOD-56171 | biostudies-arrayexpress
Project description:In S. cerevisiae, replication timing is controlled by epigenetic mechanisms restricting the accessibility of origins to limiting initiation factors. About 30% of these origins are located within repetitive DNA sequences such as the ribosomal DNA (rDNA) array, but their regulation is poorly understood. Here, we have investigated how histone deacetylases (HDACs) control the replication program in budding yeast. This analysis revealed that two HDACs, Rpd3 and Sir2, control replication timing in an opposite manner. Whereas Rpd3 delays initiation at late origins, Sir2 is required for the timely activation of early origins. Moreover, Sir2 represses initiation at rDNA origins whereas Rpd3 counteracts this effect. Remarkably, deletion of SIR2 restored normal replication in rpd3 cells by reactivating rDNA origins. Together, these data indicate that HDACs control the replication timing program in budding yeast by modulating the ability of repeated origins to compete with single-copy origins for limiting initiation factors. BrdU-IP-seq analysis of origin activity in wt, sir2 and rpd3 cells, aligned against genomic DNA (sacCer3) and rDNA sequences Please note that the wt WCE #1 and #2 samples are whole-cell extracts from wild-type cells arrested in HU that were used to calculate the log ratio of the BrdU IP #1 and #2 batches, respectively.
2014-05-14 | E-GEOD-57617 | biostudies-arrayexpress
Project description: Not available
| S-EPMC4304868 | biostudies-literature