Expression data from Saccharomyces cerevisiae with Rnase H overexpression
ABSTRACT: Transcripts up- or down-regulated comparing a strain where Rnase H is ectopically overexpressed versus wild type (empty vector); assessing the effect of DNA:RNA hybrid degradation on the transcriptome. Strains harboring the RNase H1 over-expression plasmid (p425-GPD-RNase H1) or control plasmid (p425-GPD) were grown in SC-Leucine at 30°C. For both sets of microarray experiments, duplicate cultures were analyzed. Total RNA was isolated from 1 unit of A600 mid-log phase cells using a RiboPure Yeast kit (A&B Applied Biosystems), amplified, labeled and fragmented using a Message Apm III RNA Amplification Kit (A&B Applied Biosystems) and hybridized to a GeneChIP Yeast Genome 2.0 array using the GeneChip Hybridization, Wash, and Stain Kit (Affymetrix). Arrays were scanned by the Gene Chip Scanner 3000 7G and expression data was extracted using Expression Console™ Software (Affymetrix) with the MAS5.0 statistical algorithm.
Project description:The nucleosome plays a central role in genome regulation. Traditional methods for mapping nucleosomes depend on the resistance of the nucleosome core to micrococcal nuclease (MNase). However, the lengths of the protected DNA fragments are heterogeneous, limiting the accuracy of nucleosome position information. To resolve this problem, we removed residual linker DNA by simultaneous digestion of yeast chromatin with MNase and exonuclease III (ExoIII). Paired-end sequencing of mono-nucleosomes revealed not only core particles (145-147 bp), but also intermediate particles in which ~8 bp project from one side (154 bp) or both sides (161 bp) of the nucleosome core. We term these particles "pseudo-chromatosomes" because they are present in yeast lacking linker histone. They are also observed after MNase-ExoIII digestion of chromatin reconstituted using recombinant core histones. We propose that the pseudo-chromatosome provides a DNA framework to facilitate H1 binding. Comparison of budding yeast nucleosome sequences obtained using micrococcal nuclease (MNase-seq) and MNase + exonuclease III (ExoIII) (MNase-ExoIII-seq): wild type cells and hho1-null cells. Nucleosome sequences from native chromatin and H1-depleted chromatin from mouse liver. Nucleosome sequences from a plasmid reconstituted into nucleosomes using recombinant yeast histones or native chicken erythrocyte histones.
Project description:Linker histones are involved in the formation of higher-order chromatin structure. Although linker histones have been implicated in the regulation of specific genes, it still remains unclear what their principal binding determinants are and how their repressive function in vitro can be reconciled with presumed broad binding in vivo. We generated a full genome, high resolution binding map of linker histone H1 in Drosophila Kc cells, using DamID. H1 binds at similar levels across much of the genome, both in classical euchromatin and heterochromatin. Strikingly, there are pronounced dips of low H1 occupancy around transcription start sites of active genes and at many distant cis-regulatory sites. H1 dips are not due to lack of nucleosomes. Rather, all regions with low binding of H1 show enrichment of the histone variant H3.3 which itself has been linked to high nucleosome turnover. Upon knockdown of H3.3, we find that H1 levels increase at sites previously not covered with H1 with a concomitant increase in nucleosome repeat length. These changes are independent of transcriptional changes. Our results show that the H3.3 protein counteracts association of H1 at genomic sites with high rates of histone turnover. This antagonism provides a mechanism to keep diverse genomic sites in an open chromatin conformation. For this study, we generated DamID profiles of histone H1 and RpII18 in Drosophila Kc167 cells. Additionally, we generated H1 profiles in cells treated with RNAi against white, H3.3B, or H3.3A and H3.3B. Nucleosome positioning profiles were generated in untreated cells and cells treated with RNAi against white, H3.3B, or H3.3A and H3.3B. Profiles of expression changes were generated for H3.3B RNAi and H3.3A and H3.3B RNAi. DamID experiments for H1 and RpII18 were performed in Drosophila cell cultures. Samples were hybridized to 380k NimbleGen arrays with 300 bp probe spacing. Formaldehyde-assisted isolation of regulatotry elements (FAIRE) was performed in Drosophila Kc167 cells. Samples were hybridized to 380k NimbleGen arrays with 300 bp probe spacing over non-crosslinked genomic DNA. Nucleosome positioning profiles were made by hybridizing mononucleosomal DNA over MNase digested purified genomic DNA on 380k NimbleGen arrays with 10 bp probe spacing. Expression profiles were made as H3.3 RNAi over white RNAi cohybridizations on spotted INDAC long oligo arrays. Every experiment was done in duplicate in the reverse dye orientation.
Project description:Oscillatory gene expression is fundamental to mammalian development, but technologies to monitor expression oscillations are limited. We have developed a statistical approach called Oscope to identify and characterize the transcriptional dynamics of oscillating genes in single-cell RNA-seq data from an unsynchronized cell population. Applications to a number of data sets, include a single-cell RNA-seq data set of human embroyonic stem cells (hESCs), demonstrate advantages of the approach and also identify a potential artifact in the Fluidigm C1 platform. Total 213 H1 single cells and 247 H1-Fucci single cells were sequenced. The 213 H1 cells were used to evaluate Oscope in identifying oscillatory genes. The H1-Fucci cells were used to confirm the cell cycle gene cluster identified by Oscope in the H1 hESCs.
Project description:Two types of RNA:DNA associations can lead to genome instability: the formation of R-loops during transcription and the incorporation of ribonucleotide monophosphates (rNMPs) into DNA during replication. Both ribonuclease (RNase) H1 and RNase H2 degrade the RNA component of R-loops, whereas only RNase H2 can remove one or a few rNMPs from DNA. We performed high-resolution mapping of mitotic recombination events throughout the yeast genome in diploid strains of Saccharomyces cerevisiae lacking RNase H1 (rnh1Δ), RNase H2 (rnh201Δ), or both RNase H1 and RNase H2 (rnh1Δ rnh201Δ). We found little effect on recombination in the rnh1Δ strain, but elevated recombination in both the rnh201Δ and the double-mutant strains; levels of recombination in the double mutant were about 50% higher than in the rnh201 single-mutant strain. An rnh201Δ mutant that additionally contained a mutation that reduces rNMP incorporation by DNA polymerase ε (pol2-M644L) had a level of instability similar to that observed in the presence of wild-type Polε. This result suggests that the elevated recombination observed in the absence of only RNase H2 is primarily a consequence of R loops rather than misincorporated rNMPs. The details of these experiments are in press in Genetics This diploid S.cerevisiae strain used here is a hybrid between W303-1A and YJM789. The backgrounds are diverged by about 50,000 polymorphisms that are surveyed by custom CGH microarrays containing SNP-specific probes (St. Charles et al., 2012; Genetics 190: 1267-1284; PMID 22267500). The whole genome array surveyed loss of heterozygosity (LOH) events throughout the genome of in wild type, pol2-M644L, rnh1Δ, rnh201Δ, rnh201Δ pol2-M644L, and rnh1Δ rnh201Δ mutant backgrounds in 10, 12, 10, 19, 17, and 22 samples, respectively. The names of these strains are KO_198,KO_234, KO_73, KO_75, KO_244, and KO_5, respectively. Another assay was performed mapping reciprocal crossover events on the right arm of chromosome IV in the rnh201Δ (strains KO_135 and KO188) and the rnh1Δrnh201Δ (strain KO_132) mutant backgrounds. A reporter system with a wild type ADE2 on the end of chromosome IV allowed us to detect crossovers by seeing a red-white sectored colony. Each reciprocal event was mapped by doing a microarray specific for the right arm of chromosome IV (St. Charles and Petes, 2013; PLoS Genet. 1267-1284 PMCID PMC3616911) on the red and white sides of sectors. 21 sectors were analyzed for the rnh201Δ mutant while 14 were analyzed for the rnh1Δ rnh201Δ mutant. We mapped crossovers on the right arm of chromosome IV in the rnh201Δ mutant in four different diploid isolates: KO135_5 (1R/1W, 2R/2W, 4R/4W, 5R/5W, 12R/12W, and 13R/13W), KO_135_6 (1R/1W, 4R/4W, 5R/5W, 7R/7W, 9R/9W, 11R/11W, 13R/13W, and 17R/17W), KO 188_1 (1R/1W, and 4R/4W), and KO188_2 (6R/6W, 7R/7W, 11R/11W, and 12R/12W). We mapped crossovers on the right arm of chromosome IV in the rnh1Δ rnh201Δ mutant in two different diploid isolates: KO_132_31 (2R/2W, 6R/6W, 8R/8W, 15R/15W, 17R/17W, 21R/21W, 22R/22W, and 24R/24W) and KO_132_29 (3R/3W, 7R/7W, 18R/18W, 24R/24W, and 34R/34W).
Project description:Yeast knockout strains were constructed by the Yeast Deletion Project. Three biological replicates were analyzed for each strain. 5 ml cultures were inoculated at OD600 = 0.2 from saturated overnight cultures and grown to mid-log phase (OD600 = 0.6 - 0.8) in YPD media 37 or in phosphate-depleted media 38 at 30C. Cells were harvested by centrifugation and washed with nuclease-free water (Ambion). Total RNA was isolated immediately after harvest using the Ribopure Yeast RNA Isolation Kit (Ambion). 5 mg of total RNA was used to generate labeled probes with standard Affymetrix protocols.
Project description:Mesenchymal stem/stromal cells (MSCs) are multipotent cells that can differentiate into a variety of cell types forming connective tissue and skeleton, and are essential participants in the development of all organs. However, MSC precursors remain largely unknown. In human embryonic stem cells (hESCs) directed to mesendodermal differentiation through coculture with OP9 stromal cells, we identified a population of mesodermal cells by surface expression of apelin receptor (APLNR1). APLNR+ cells were enriched with precursors generating compact spheroid colonies in semisolid suspension culture. Being formed by single cells, these colonies consisted of a uniform population of mesenchymal cells with a transcriptional profile representative of embryonic mesenchyme originating from lateral plate/extraembryonic mesoderm. Mesenchymal colony formation required serum-free medium and FGF2 as a colony-forming factor, could be significantly enhanced by PDGF-BB, but suppressed by VEGF. When transferred to the adherent cultures in serum-free medium with FGF2, individual colonies gave rise to multipotential mesenchymal cell lines with typical phenotype (CD146+CD105+CD73+CD31-CD43-CD45-), differentiation (chondro-, osteo-, and adipogenesis) and proliferation (>80 doublings) potentials. Consistent with lineage-restricted differentiation pattern, neither endothelial nor hematopoietic cells could be produced from adherent mesenchymal cultures, however endothelial cells could be derived from mesenchymal colonies in the early days of colony-forming culture suggesting that mesenchymal cells arose from cells with primary angiogenic potential (mesangioblasts). Together these studies identified mesangioblasts as the earliest clonogenic mesenchymal precursors at this stage of their specification from mesoderm. This set (11 samples) of expression data is sequential stages of MSC development from hESCs (H1), namely ALPNR+ mesodermal precursors isolated on day 2 and day 3 differentiation, mesangioblast (MB) cores (Day 2 H1-derived cores), hemangioblast (HB) cores (day 3 H1-derived cores), mesangioblast (MB) and hemangioblast (HB) colonies, and colony-derived MSC lines at passage 1 and 5.
Project description:Leaf colour variation is observed in several plants. We obtained two types of branches with yellow (H1) and variegated (H2) leaves from Camellia sinensis. To reveal the mechanisms that underlie the leaf colour variations, proteomic analysis using label-free MS-based approach was performed using leaves from variants and normal branches (CKs).
Project description:In chicken DT40 cells, there are six linker histone H1 variants and 12 of coding genes. We have previously reported of 11 out of 12 H1 knock out DT40 cells (Takami et al., Genes to Cell 1997 [PMID:9491804]) but complete H1 null DT40 cells could not established, so far. We identified one of the H1 variant, H1R was involved in genomic instabilities (Hashimoto et al., DNA repair (2007) ), so we re-introduced floxed H1R-eGFP and mer-cre-mer into 11 out of 12 H1 knock out DT40 cells. Then we targeted last enedogenous H1, we successfully established conditional H1 KO cells (K11). Next we treated with tamoxifen to loop out floxed H1R-eGFP, and cloning H1 completely null cells (K11-5, and K11-7). We analysis those gene expression pattern in wild-type, K11, and K11-5 cells Experiment Overall Design: Apoptosis is induced in H1 null cells, so we inhibit apoptosis with pan-caspase inhibitor, Z-VAD-FMK and extract RNAs.
Project description:During transcription the nascent RNA can invade the DNA template, forming extended RNA-DNA duplexes (R-loops). Here we employ ChIP-seq in strains expressing or lacking RNase H to map targets of RNase H activity throughout budding yeast genome. In wild-type strains, R-loops were readily detected over the 35S rDNA region transcribed by Pol I and over the 5S rDNA transcribed by Pol III. In strains lacking RNase H activity, R-loops were elevated over other Pol III genes notably tRNAs, SCR1 and U6 snRNA, and were also associated with the cDNAs of endogenous TY1 retrotransposons, which showed increased rates of mobility to the 5?-flanking regions of tRNA genes. Unexpectedly, R-loops were also associated with mitochondrial genes in the absence of RNase H1, but not of RNase H2. Finally, R-loops were detected on highly expressed protein-coding genes in the wild-type, notably over the second exon of spliced ribosomal protein genes. ChIP-seq of RNA-DNA hybrids using antibody S9.6