Project description:ChIP-chip of Pol II, H3K36me3 and CENP-A in met-1 C. elegans early embryo EXPERIMENT TYPE: CHIP-chip. BIOLOGICAL SOURCE: Strain: met-1(n4337); Developmental Stage: Early Embryo; Genotype: met-1(n4337); Sex: population predominantly Hermaphrodites perhaps with some Males; NUMBER OF REPLICATES: 2; EXPERIMENTAL FACTORS: temperature 20
Project description:ChIP-chip of Mes-4, H3K36me3 and H3K27me3 in N2 C. elegans early embryo EXPERIMENT TYPE: CHIP-chip. BIOLOGICAL SOURCE: Strain: N2; Developmental Stage: Early Embryo; Genotype: N2; Sex: population predominantly Hermaphrodites perhaps with some Males; NUMBER OF REPLICATES: 2 or 3; EXPERIMENTAL FACTORS: temperature 20
Project description:ChIP-chip of MES-4, H3K36me3 and H3K27me3 in mes-4 RNAi C. elegans early embryo EXPERIMENT TYPE: CHIP-chip. BIOLOGICAL SOURCE: Strain: mes-4 RNAi; Developmental Stage: Early Embryo; Genotype: N2; Sex: population predominantly Hermaphrodites perhaps with some Males; NUMBER OF REPLICATES: 2; EXPERIMENTAL FACTORS: temperature 24
Project description:We find that CENP-T acts as a bridge between two well-positioned CENP-A nucleosomes that are present on young alpha-satellite dimers that dominate functional human centromeres. CENP-T is centered over the CENP-B box, where it interacts with the CENP-B/CENP-C complex. Upon cross-linking, the entire CENP-A/CENP-C/CENP-T-containing complex is recovered as a nuclease-protected particle over an alpha-satellite dimer that comprises the fundamental unit of kinetochore chromatin. Our work reveals that CENP-A/CENP-C and CENP-T branches of kinetochore assembly are physically integrated.
Project description:To understand the transcriptional basis of circadian rhythms in mouse liver, we generated genome-wide profiles of RNA polymerase II (Pol 2) DNA occupancy and the histone modifications H3K4me3 and H3K36me3 around the circadian cycle. We found that Pol 2 occupancy at promoters and in gene bodies cycle in synchrony, suggesting that Pol 2 recruitment at promoters underlies circadian gene transcription. On average, Pol 2 occupancy precedes mRNA accumulation by about three hours. Promoters of transcribed genes have tri-methylated H3K4 residues even at their trough activity times, and the tri-methylation levels increase in phase with Pol 2 loading. In contrast, the tri-methylation of H3K36 residues lags transcription by three hours with amplitudes that are markedly shallower, indicating that this mark is less dynamic on the circadian time scale. The comparison of Pol 2 occupancy and mRNA accumulation revealed that both transcriptional and post-transcriptional regulatory mechanisms can account for diurnal mRNA profiles. Additional processed data and visualization tools are available at http://cyclix.vital-it.ch/ Contributed by members of CycliX consortium (http://cyclix.vital-it.ch/) 28 samples examinded, 7 Polr2b, 7 H3K4me3, 7 H3k36me3, 7 input samples.
Project description:At Schizosaccharomyces pombe centromeres, heterochromatin formation is required for de novo incorporation of the histone H3 variant CENP-A/Cnp1, which in turn directs kinetochore assembly and ultimately chromosome segregation during mitosis. Noncoding RNAs (ncRNAs) transcribed by RNA polymerase II (Pol II) directs heterochromatin formation via the RNAi machinery, but also through RNAiindependent RNA processing factors. Control of centromeric ncRNA transcription is therefore a key factor for proper centromere function. We here use transcriptional profiling, gene inactivation experiments, and chromatin immunoprecipitation analyses to demonstrate that the Mediator complex directs ncRNA transcription and regulates centromeric heterochromatin formation in fission yeast. Mediator co-localizes with Pol II at centromeres and loss of the Mediator subunit Med20 causes a dramatic increase in pericentromeric transcription and desilencing of the core centromere. As a consequence, heterochromatin formation is impaired both via the RNAi dependent and independent pathways, resulting in loss of CENP-A/Cnp1 from the core centromere, defect kinetochore function, and a severe chromosome segregation defect. Interestingly, the increased centromeric transcription observed in med20Δ appears to directly block CENP-A/Cnp1 incorporation and inhibition of Pol II transcription can suppress the observed phenotypes. Our data thus identify Mediator as a crucial regulator of ncRNA transcription at fission yeast centromeres and add another crucial layer of regulation to centromere function. 3 samples examined: wild type chromatin incubated with beads as the non antibody control, wild type chromatin incubated with RNA Polymerase II CTD domain antibody and Protein G beads, and TAP-Med7 cells chromatin incubated with IgG beads.