Strand-specific ChIP-seq profiling of Rad52 localization
Ontology highlight
ABSTRACT:
ORGANISM(S): Schizosaccharomyces pombe
SUBMITTER: Zhi-Xiong Zhou
PROVIDER: E-GEOD-39166 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:RNA interference is involved in silencing of transposable and repetitive elements. How these elements are initially recognized by RNAi is a fundamental and unanswered question. We previously identified a class of Dicer-independent small RNAs, called primal small RNAs (priRNAs), in fission yeast. The mechanism by which Dicer-independent small RNAs are generated is not clear for any species. Here we reconstitute priRNA biogenesis in vitro and demonstrate that priRNAs can nucleate RNAi in vivo. We identify 3'-5' exonuclease Trimmer and show that Argonaute, loaded with longer RNA precursors, recruits Trimmer to generate the new 3' end. Next, we show that antisense priRNAs accumulate in rrp6M-NM-^T cells and nucleate RNAi at subset of protein coding genes in a Trimmer- and priRNA-dependent manner. Thus, Rrp6-mediated degradation of antisense transcripts and priRNA precursors protects the genome from spurious RNAi. Our results suggest that Argonaute association with random RNA degradation products triggers RNAi in a process of transcriptome surveillance. small RNA profiling in wild type S. pombe cells and in mutant cells
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Project description:Alternative splicing (AS) generates transcript variants by the definition of different exonic and intronic regions and causes a massive expansion of transcriptome diversity. Changes in AS patterns have been found to be linked to manifold biological processes, yet fundamental aspects such as the regulation of AS and the functional implications of altered AS programs largely remain to be addressed. In this work, widespread AS regulation by Arabidopsis Polypyrimidine tract-binding protein homologues (AtPTBs) was revealed. In total 452 AS events derived from 308 distinct genes were found to be responsive to the levels of the splicing factors AtPTB1 and AtPTB2, which predominantly triggered splicing of regulated introns, inclusion of cassette exons, and usage of upstream 5' splice sites. In contrast, alternative 3' splice site events were strongly underrepresented among the AtPTB1/2 targets and no major AS regulatory function of the distantly related AtPTB3 was found. Dependent on their position within the mRNA, AtPTB-regulated events can both modify the untranslated regions and give rise to alternative protein products. Gene ontology analysis revealed a connection of AtPTB-mediated AS control with diverse biological processes, and the functional implications of selected AS events were further elucidated in the context of seed germination and flowering time control. Specifically, AtPTB misexpression changes AS of the PHYTOCHROME INTERACTING FACTOR 6 (PIF6) pre-mRNA, coinciding with altered rates of abscisic acid-dependent seed germination. Furthermore, AS patterns as well as the expression of key flowering regulators were massively changed in an AtPTB1/2 level-dependent manner. In conclusion, our work has revealed widespread AS regulatory functions of the AtPTB splicing factors with important functional implications in various fundamental processes of Arabidopsis development. Analysis of alternative splicing patterns in plants with increased and decreased levels of the 3 Arabidopsis Polypyrimidine-tract binding protein homologues in comparison to wild type samples, determined in duplicates
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Project description:The experiment was performed to assess the importance of nucleosome eviction for the binding of condensin to chromatin during mitosis. The condensin complex associates with chromatin during mitosis to ensure chromosome condensation and accurate segregation, but how this binding is achieved remains poorly understood. Our study indicates that transcription co-activators Gcn5 and Mst2 assist condensin binding during mitosis by evicting nucleosomes. To reach this conclusion, we mapped nucleosomes, during mitosis, in wild-type and gcn5mst2 mutant strains. This experiment allowed us (1) to identify nucleosome-depleted regions (ndrs) during mitosis and to show that condensin tends to colocalize with ndr at the 3ends of genes, and (2) to confirm the importance of nucleosome eviction from ndrs by gcn5 and mst2, during mitosis, for the binding of condensin to chromatin.this experiment determines the patterns of nucleosomes in wild type and mutant fission yeast cells arrested in early mitosis. We analysed wild-type cells, cells lacking Gcn5 histone acetylatransferase (gcn5D) and cells lacking both Gcn5 and Mst2 histone acetyltransferases (Gcn5Dmst2D). All cells used in this study expressed a GFP-tagged version of condensin (Cnd2-GFP) and were blocked in early mitosis at 19C by the nda3-KM311 mutation. Mitotic indexes were determined by scoring the accumulation of Cnd2-GFP in the nucleus. Mitotic cells were collected and chromatin was digested by increasing amount of MNase to produce mononucleosomes. Mononucleosomal DNA was purified on an agarose gel and sequence on an Illumina Nextseq 500 apparatus. Three replicates of wild type, gcn5D and gcn5Dmst2D were analysed. Nucleosome patterns were determined in wild-type cells, cells lacking Gcn5 and cells lacking both Gcn5 and Mst2.
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