ABSTRACT: DNA duplication is intimately connected to setting up post-replicative chromosome structures and events, but molecular details of this coordination are not well understood. A striking example occurs during yeast meiosis, where replication locally influences timing of the DNA double-strand breaks (DSBs) that initiate recombination. We show here that replication-DSB coordination is eliminated by overexpressing Dbf4-dependent Cdc7 kinase (DDK) or removing Tof1 or Csm3, components of the replication fork protection complex (FPC). DDK physically associates with Tof1, and Tof1 is dispensable for replication-DSB coordination if DDK is artificially tethered to replisomes. Furthermore, DDK phosphorylation of the DSB-promoting factor Mer2 is locally coordinated with replication, dependent on Tof1. These findings indicate that DDK recruited by FPC to replisomes phosphorylates chromatin-bound Mer2 in the wake of the replication fork, thus synchronizing replication with an early prerequisite for DSB formation. This may be a general mechanism to ensure spatial and temporal coordination of replication with other chromosomal processes. Ninety-six samples total: 12 time points (each time points contains ChIP and input samples) from Rec114-myc ARS+, Rec114-myc ars∆ strains, Rec114-myc tof1∆ARS+ and Rec114-myc tof1∆ ars∆ strains
Project description:We investigated EZH2 binding in the presence and absence of MMSET protein. MMSET overexpression in t(4;14)+ myeloma leads to global loss of H3K27 methylation and redistribution of EZH2 binding throughout the genome ChIP-seq for EZH2 in two cell types
Project description:Synergistic activation of inflammatory cytokine genes by IFN-gamma and TLR signaling is important for innate immunity and inflammatory disease pathogenesis, but underlying mechanisms are not known. By obtaining over three billion bases of sequence from chromatin immunoprecipitated DNA, we generated genome-wide chromatin-state maps of human primary monocytes under IFN-gamma-priming and TLR stimulation. We found that IFN-gamma induced genome-wide sustained occupancy of STAT1, IRF-1 and associated histone acetylation at TSS-proximal and distal regulatory elements and provided a synergy mechanism whereby IFN-gamma creates a primed chromatin environment to augment TLR-induced gene transcription, which suggest therapeutic approaches that selectively target priming mechanisms. Examination and comparison of the changes in TF binding and histone modification in human primary monocytes under different conditions.
Project description:Elucidating the global function of a transcription factor implies the identification of its target genes and genomic binding sites. The role of chromatin in this context is unclear, but the dominant view is that factors bind preferentially to nucleosome-depleted regions, identified as DNaseI-hypersensitive sites (DHS). Here we show by chromatin-IP, MNase and DNaseI assays followed by deep sequencing that the progesterone receptor (PR) requires nucleosomes for optimal binding and function. In breast cancer cells treated with progestins we identified 25,000 PR binding sites (PRbs), the majority encompassing several copies of the hexanucleotide TGTYCY, highly abundant in the genome. We found that functional PRbs accumulate around progesterone-induced genes mainly in enhancers, are enriched in DHS but exhibit high nucleosome occupancy. Progestin stimulation results in remodeling of these nucleosomes with displacement of histones H1 and H2A/H2B dimers. Our results strongly suggest that nucleosomes are crucial for PR binding and hormonal gene regulation. T47D-MTVL human breast cancer cells were incubated with the progestin R5020 for different times between 0 to 360 minutes at 37ºC. ChIP-seq experiments were performed using antibodies against progesterone receptor and a single Sample each with anti-H3K4me3 and anti-H3K4me1. Mononucleosomal DNA was prepared from cells untreated or stimulated 60 min with R5020 and subjected to deep sequencing using the Solexa Genome Analyzer.
Project description:DNA duplication is intimately connected to setting up post-replicative chromosome structures and events, but molecular details of this coordination are not well understood. A striking example occurs during yeast meiosis, where replication locally influences timing of the DNA double-strand breaks (DSBs) that initiate recombination. We show here that replication-DSB coordination is eliminated by overexpressing Dbf4-dependent Cdc7 kinase (DDK) or removing Tof1 or Csm3, components of the replication fork protection complex (FPC). DDK physically associates with Tof1, and Tof1 is dispensable for replication-DSB coordination if DDK is artificially tethered to replisomes. Furthermore, DDK phosphorylation of the DSB-promoting factor Mer2 is locally coordinated with replication, dependent on Tof1. These findings indicate that DDK recruited by FPC to replisomes phosphorylates chromatin-bound Mer2 in the wake of the replication fork, thus synchronizing replication with an early prerequisite for DSB formation. This may be a general mechanism to ensure spatial and temporal coordination of replication with other chromosomal processes. Forty-eight samples total: 8 time points from WT ARS+, WT ars∆, DDK OP ARS+, DDK OP ars∆,tof1∆ ARS+,tof1∆ ars∆ strains
Project description:GATA factors interact with simple DNA motifs (WGATAR) to regulate critical processes, including hematopoiesis, but very few WGATAR motifs are occupied in genomes. Given the rudimentary knowledge of mechanisms underlying this restriction, and how GATA factors establish genetic networks, we used ChIP-seq to define GATA-1 and GATA-2 occupancy genome-wide in erythroid cells. Coupled with genetic complementation analysis and transcriptional profiling, these studies revealed a rich collection of targets containing a characteristic binding motif of greater complexity than WGATAR. GATA factors occupied loci encoding multiple components of the Scl/TAL1 complex, a master regulator of hematopoiesis and leukemogenic target. Mechanistic analyses provided evidence for cross-regulatory and autoregulatory interactions among components of this complex, including GATA-2 induction of the hematopoietic corepressor ETO-2 and an ETO-2 negative autoregulatory loop. These results establish fundamental principles underlying GATA factor mechanisms in chromatin and illustrate a complex network of considerable importance for the control of hematopoiesis. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf Examination of GATA1 and GATA2 occpancy in K562 cells
Project description:Human MBT domain-containing protein L3MBTL2 was found to be an integral component of a protein complex that we termed Polycomb Repressive Complex 1-like 3 (PRC1L3) given the presence of the PcG proteins RING1, RING2 and PCGF6. L3MBTL2 binds chromatin in a histone modification-independent manner and is required for the repressive function of PRC1L3. PRC1L3 also contains E2F6 and CBX3, two factors with well‐established functions in transcriptional repression. Genome‐wide profiling identified several hundred genes that are simultaneously bound by L3MBTL2 and E2F6, preferentially around transcriptional start sites. Importantly, these genes are largely distinct from those targeted by other E2Fs or L3MBTL, another MBT‐domain containing protein that interacts with RB1. H3K27 or H3K9 methylation, two chromatin modifications implicated in gene silencing, are not present on all L3MBTL2 target genes. L3MBTL2-specific RNAi results in altered target gene expression patterns and affects the differentiation program of hematopoietic cells. Our data suggest that repression of transcription via chromatin modulation, reflective of PRC1 function, can be achieved by multiple players and does not necessarily require the presence of histone lysine methylation marks. 7 total ChIP-seq datasets; one L3MBTL2 dataset done in duplicate in K562 cells; one E2F6 dataset done in duplicate in K562 cells; one H3K27me3 replicate dataset in K562 cells.
Project description:The clustered homeobox proteins play crucial roles in development, hematopoiesis and leukemia yet the targets they regulate and their mechanisms of action are poorly understood. Here, we identified the binding sites for Hoxa9 and the Hox cofactor Meis1 on a genome-wide level and profiled their associated epigenetic modifications and transcriptional targets. Hoxa9 and the Hox cofactor Meis1 co-bind at hundreds of highly evolutionarily-conserved sites, most of which are distant from transcription start sites. These sites show high levels of histone H3K4 monomethylation and CBP/P300 binding characteristic of enhancers. Furthermore, a subset of these sites shows enhancer activity in transient transfection assays. Many Hoxa9 and Meis1 binding sites are also bound by PU.1 and other lineage-restricted transcription factors previously implicated in establishment of myeloid enhancers. Conditional Hoxa9 activation is associated with CBP/P300 recruitment, histone acetylation and transcriptional activation of a network of proto-oncogenes including Erg, Flt3, Lmo2, Myb and Sox4. Collectively this work suggests that Hoxa9 regulates transcription by interacting with enhancers of genes important for hematopoiesis and leukemia. To identify the genome-wide binding sites for Hoxa9 and the Hox cofactor Meis1
Project description:We performed genome-wide profiling of Tcf7l2 occupancy during oligodendrocyte differentiation and identified the key enzymes involved in cholesterol metabolism and essential for CNS myelination. Examination of Tcf7l2 chIP-seq in oligodendrocyte progenitor cell and 2 differentiation oligodendrocytes.
Project description:Metabolic homeostasis in mammals critically depends on the regulation of fasting-induced genes by CREB in the liver. Previous genome-wide analysis has shown that only a small percentage of CREB target genes are induced in response to fasting-associated signaling pathways. The precise molecular mechanisms by which CREB specifically targets these genes in response to alternating hormonal cues remain to be elucidated. We performed chromatin immunoprecipitation coupled to high-throughput sequencing of CREB in livers from both fasted and re-fed mice. In order to quantitatively compare the extent of CREB-DNA interactions genome-wide between these two physiological conditions we developed a novel, robust analysis method, termed the ‘single sample independence’ (SSI) test that greatly reduced the number of false positive peaks. We found that CREB remains constitutively bound to its target genes in the liver regardless of the metabolic state. Integration of the CREB cistrome with expression microarrays of fasted and re-fed mouse livers and ChIP-seq data for additional transcription factors revealed that the gene expression switches between the fasted and fed states are associated with co-localization of additional transcription factors at CREB sites. Our results support a model in which CREB is constitutively bound to thousands of potential target genes and combinatorial interactions between DNA-binding factors are necessary to achieve the specific transcriptional response of the liver to fasting. Furthermore, our genome-wide analysis identifies thousands of novel CREB target genes in liver, including a previously unknown role for CREB in regulating ER stress genes in response to nutrient influx. CREB ChIP-seq was performed on mouse liver from fasted and re-fed mice, using 5 separate biological replicates for each condition. GR and C/EBP(beta) ChIP-seq were performed as single replicates on ad-lib fed mice.
Project description:Overwintering plants are capable of exhibiting high levels of cold tolerance, which is acquired through the process of cold acclimation (CA). In contrast to CA, the acquired freezing tolerance is rapidly reduced during cold de-acclimation (DA) and plants resume growth after sensing warm temperatures. In order to better understand plant growth and development, and to aid in the breeding of cold-tolerant plants, it is important to decipher the functional mechanisms of the DA process.In this study, we performed comparative transcriptomic and proteomic analyses during CA and DA. As revealed by shotgun proteomics, we identified 3,987 peptides originating from 1,569 unique proteins and the corresponding mRNAs were analyzed. Among the 1,569 genes, 658 genes were specifically induced at the transcriptional level during the process of cold acclimation. In order to investigate the relationship between mRNA and the corresponding protein expression pattern, a Pearson correlation was analyzed. Interestingly, 199 genes showed a positive correlation of mRNA and protein expression pattern, indicating that both their transcription and translation occurred during CA. However, 226 genes showed a negative correlation of mRNA and protein expression pattern, indicating that their mRNAs were transcribed during CA and were stored for the subsequent DA step. Under this scenario, those proteins were specifically increased during DA without additional transcription of mRNA. These data indicate that the expression of specific mRNAs and subsequent accumulation of corresponding proteins are not always in accordance under low temperature stress conditions in plants.