Project description:FLAG Ab pull down of chromatin associated proteins in the stable cell line expressing RPB3-3xFLAG (with DOX). Total RNAPII interactome was measured in three conditions; Untreated, 1mM H2O2 treatment for 15 minutes, and 1 hour recovery following media washout.
Project description:Most functional studies in Saccharomyces cerevisiae are classically conducted on exponentially growing cell cultures, in the presence of high concentration of glucose. However, yeast cells rarely experience such an environment and their survival in the wild depends on their ability to withstand adverse conditions. When all glucose has been consumed and no carbon source is available, cells enter a stationary phase, a stage where most cells are in quiescence, a non-proliferative state that maintains the ability to resume growth following restoration of missing nutrients. The aim of this project is to characterize RNA Polymerase II transcriptional activity during quiescence entry.
Project description:ChIP-chip by array of Rpb3 localization in yeast with different CTD lenghts and with or without CDK8 deletion to determine the role of CTD length and Cdk8 on RNAPII localization
Project description:Our structural and biochemical studies show that S. cerevisiae RNA Polymerase II (RNAPII) homodimerizes through the stalk domain (formed by the Rpb4-Rpb7 subunits). To explore the biological impact of disrupting this interaction we introduced a triple point mutation at the RNAPII dimerization interface in Rpb7 (Q96A, H97A, F109K). To test the impact of the dimerziation mutant on RNAPII occupancy, we performed ChIP-seq using a monoclonal antibody against the Rpb3 subunit (1Y26, abcam) of RNAPII, in WT and Rpb7-QHF cells.
Project description:Cellular quiescence is coupled with cellular development, tissue homeostasis, and cancer progression. Both quiescence and cell cycle re-entry are controlled by active and precise regulation of gene expression. However, the roles of long noncoding RNAs (lncRNAs) during these processes remain to be elucidated. By performing a genome-wide transcriptome analyses, we identify thousands of differentially expressed lncRNAs, including ~30 of the less-characterized class of microRNA-host-gene lncRNAs (lnc-MIRHGs), during cellular quiescence and during serum-stimulation in human diploid cells. We observe that the mature MIR222HG display serum-stimulated induction due to enhanced pre-RNA splicing. Serum-stimulated binding of the pre-mRNA splicing factor SRSF1 to a micro-exon, which partially overlaps with the primary miR-222 precursor, facilitates enhanced MIR222HG splicing. In serum-stimulated cells, SRSF1 negatively regulates the Drosha/DGCR8-catalyzed cleavage of pri-miR-222, thereby increasing the cellular pool of the mature MIR222HG. Further, loss-of-function studies indicate that the mature MIR222HG facilitates the serum-stimulated cell cycle re-entry in a microRNA-independent manner. Mechanistically, MIR222HG, along with ILF3/2 complex, forms RNA:RNA duplex with DNM3OS lncRNA, thereby promoting DNM3OS stability. The current study identifies a mechanism in which the interplay between splicing versus microprocessor complex dictates the serum-induced expression of lnc-MIRHG MIR222HG for efficient cell cycle re-entry.
Project description:Binding profiles for H3 and H4ac were determined as cells transition from log growth to quiescence. We found that massive chromatin changes that reflect global transcriptional repression occur after the diauxic shift in an Rpd3-dependent manner. Binding of Rpd3 is dramatically expanded to reflect binding at thousands of genes after quiescence entry, demonstrating an Rpd3-driven mechanism to change chromatin and repress transcription after entry into quiescence.
Project description:The histone chaperone Spt6 is involved in promoting elongation of RNA polymerase II (RNAPII), maintaining chromatin structure, regulating co-transcriptional histone modifications, and controlling mRNA processing. These diverse functions of Spt6 are partly mediated through its interactions with RNAPII and other factors in the transcription elongation complex. In this study, we used mass spectrometry to characterize the differences in RNAPII interacting factors between wild-type cells and those depleted for Spt6, leading to the identification of proteins that depend on Spt6 for their interaction with RNAPII. In all, eight samples were processed - four genotypes (1. SPT6, RPB3-untagged; 2. SPT6, RPB3-tagged; 3. spt6-1004, RPB3-untagged; 4. spt6-1004; RPB3-tagged) in biological duplicates.
Project description:Quiescence is a distinct cell cycle phase, termed G0, in which growth, transcription, translation, and replication are suppressed. Yeast cells enter G0 following glucose exhaustion but remain viable for an extended period and can re-enter the cell cycle when returned to glucose-rich medium. Quiescence is a feature of all organisms and is essential for the maintenance of stem cells and tissue renewal. Quiescence is also related to chronological lifespan (CLS) - or the capacity of post-mitotic quiescent cells to survive over time - and thus contributes to longevity. However, important questions remain to be answered regarding the mechanisms that control entry into quiescence, the maintenance of quiescence, and the re-entry of quiescent cells into the cell cycle. Histone acetylation is lost during the formation of quiescent yeast cells, and chromatin becomes highly condensed. This unique chromatin landscape plays a key role in supporting quiescence-specific transcriptional repression and has been linked to the formation and maintenance of quiescent cells. To ask if other chromatin features regulate quiescence, we conducted a comprehensive screen of histone H3 and H4 mutants. We identified several mutants that show altered quiescence entry and have characterized their chromatin phenotypes. None of these mutants retain histone acetylation, while several have altered chromatin condensation. Additionally, a screen for H3 and H4 mutants with altered chronological lifespan showed that CLS is highly correlated with quiescence entry.
Project description:To determine the interactome of RNA Polymerase II (RNAPII), HA-tagged RPB3 was stably expressed in U2OS cells. The cells were harvested followed by the native stepwise isolation of chromatin-associated RNAPII complexes. HA-RPB3 was immunoprecipitated and interacting proteins analyzed by quantitative mass spectrometry. U2OS cells expressing no HA-tagged protein were used for comparison.