Project description:The essential role of the core histones (H2A, H2B, H3 and H4) in DNA packaging has been well understood for decades, but the function of the linker histone (H1) remains enigmatic. H1 compacts nucleosome arrays in vitro, but the multiple H1 subtypes and variants encoded in mammalian genomes (11 in both mice and humans) hamper genetic studies to determine H1 function in vivo. Challenging the prevailing view that linker histones are a general feature of heterochromatin, here we show a critical requirement for linker histones in the function of Polycomb Repressive complex 2 (PRC2). Through a CRISPR/Cas9 genetic screen in a fluorescent reporter cell line responsive to PRC2 perturbation, we identified an essential requirement for the poorly characterised gene CRAMP1 in PRC2-mediated repression. CRAMP1 localises to the promoters of all expressed H1 genes where it acts as a positive transcriptional regulator. Ablation of CRAMP1 provides a unique tool to simultaneously deplete all linker histones, which results in selective decompaction of H3K27me3-marked loci and derepression of PRC2 target genes without concomitant loss of PRC2 occupancy or enzymatic activity. Strikingly, in contrast to the broad genomic distribution previously ascribed to H1, we find that linker histones selectively localise to genomic loci marked by H3K27me3 across diverse cell types and organisms. Altogether, our data demonstrate a prominent role for linker histones in epigenetic repression by PRC2.
Project description:Expression profiling of C. elegans mid-L3 larvae to identify high-expressed and low-expressed subsets of genes in C. elegans L3 larvae.
Project description:modENCODE_submission_5073 This submission comes from a modENCODE project of Gary Karpen. For full list of modENCODE projects, see http://www.genome.gov/26524648 Project Goal: We aim to determine the locations of the major histone modifications across the Drosophila melanogaster genome. The modifications under study are involved in basic chromosomal functions such as DNA replication, gene expression, gene silencing, and inheritance. We will perform Chromatin ImmunoPrecipitation (ChIP) using the Illumina NGS sequencing platform. We will initially assay localizations using chromatin from three cell lines and two embryonic stages, and will then extend the analysis of a subset of proteins to four additional animal tissues/stages. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf EXPERIMENT TYPE: CHIP-seq. BIOLOGICAL SOURCE: Strain: Oregon-R(official name : Oregon-R-modENCODE genotype : wild type ); Developmental Stage: 3rd Instar Larvae; Genotype: wild type; EXPERIMENTAL FACTORS: Strain Oregon-R(official name : Oregon-R-modENCODE genotype : wild type ); Antibody H1 (target is H1); Developmental Stage 3rd Instar Larvae
Project description:To identify genes differentially expressed during L3 lethargus, we collected RNA during the third larval stage (L3) lethargus period, 37 hours after feeding developmentally-arrested L1 animals. Animals in lethargus were identified based on quiescence of locomotion and feeding. Additional time point for RNA collection was in the mid-L3 stage, 32 hours after feeding developmentally-arrested L1 animals. These samples were interrogated with the Affymetrix C. elegans Genome Array. A total of 153 gene transcripts were up regulated, and 48 gene transcripts were down regulated, during the L3 lethargus period compared to the L3 stage (false discovery rate (FDR) < 0.05).
Project description:We performed RNA-seq analysis of WT and blmp-1(tm548) mutant L3 larvae to identify genes regulated by the zing-finger transcription factor BLMP-1.
Project description:To identify genes differentially expressed during L3 lethargus, we collected RNA during the third larval stage (L3) lethargus period, 37 hours after feeding developmentally-arrested L1 animals. Animals in lethargus were identified based on quiescence of locomotion and feeding. Additional time point for RNA collection was in the mid-L3 stage, 32 hours after feeding developmentally-arrested L1 animals. These samples were interrogated with the Affymetrix C. elegans Genome Array. A total of 153 gene transcripts were up regulated, and 48 gene transcripts were down regulated, during the L3 lethargus period compared to the L3 stage (false discovery rate (FDR) < 0.05). There were 2 groups and 3x replication for each group, for 6 total samples. The groups were (1) L3 and (2) L3-lethargus. We compared L3-lethargus vs L3 using R/maanova. The permutation based p-values for each test were significant for FDRM-bM-^IM-$5%.