Project description:Dynamic changes of histone epigenetic modifications and chromatin structure represent an universal mechanism by which cells adapt their transcriptional response to rapidly changing environmental conditions. During neuronal development, extensive chromatin remodeling takes place allowing the transition of pluripotent cells into differentiated neurons. Here we report that the ATP-dependent chromatin remodeling complex NuRD, which couples ATP-dependent nucleosome sliding with histone deacetylase activity, is a major remodeling complex in embryonic brain and plays an instructive role during mouse neuronal development. Importantly, the ATPase subunits of NuRD complex CHD3, CHD4 and CHD5 undergo a functional switch, thereby regulating distinct aspects of neuronal differentiation and migration in a sequential and mostly non-overlapping manner. We conclude that the recruitment of NuRD complexes containing specific CHDs to gene promoters and enhancers plays an instructive role in brain development. Gene expression analysis was performed in the mouse embryonic cortex at three developmental stages: E12.5, E15.5 and E18.5 using total RNA obtained from four embryos for each time point.
Project description:We carried out multiple functional genomic assays in Capsaspora owczarzaki, the unicellular relative of animals with the largest known gene repertoire for transcriptional regulation. We show that changing chromatin states, differential lincRNA expression and dynamic cis-regulatory sites are associated with life cycle transitions in Capsaspora.
Project description:The transcription factor CCCTC-binding factor (CTCF) modulates pleiotropic functions mostly related to gene expression regulation. The role of CTCF in large scale genome organization is also well established. A unifying model to explain relationships between many CTCF-mediated activities involve direct or indirect interactions with numerous protein cofactors recruited to specific binding sites. The co-association of CTCF with other architectural proteins such as cohesin, chromodomain helicases and BRG1 further support the interplay between master regulators of mammalian genome folding. Here we report a comprehensive LC-MS/MS mapping of the components of the SWI/SNF chromatin remodeling complex co-associated with CTCF including subunits belonging to the core, signature and ATPase modules. We further show that the localization patterns of representative SWI/SNF members significantly overlap with CTCF sites on transcriptionally active chromatin regions. Moreover, we provide evidence of a direct binding of the BRK-BRG1 domain to the zinc finger motifs 4-8 of CTCF, thus suggesting that these domains mediate the interaction of CTCF with the SWI/SNF complex. These findings provide an updated view of the cooperative nature between CTCF and the SWI/SNF ATP-dependent chromatin-remodeling complexes, an important step for understanding how these architectural proteins collaborate to shape the genome.
Project description:We studied the extent of chromatin remodeling in an in-vitro model of the epithelial-mesenchymal transition (EMT). EMT is induced in spheroid cultures (3D) using simultaneously two cytokines: TGFbeta and TNFalpha. The epithelial-mesenchymal transition (EMT) is a cellular de-differentiation process that has been implicated in cancer progression and metastasis. Increasing evidence suggests that EMT is regulated and established by epigenetic reprogramming, however a systems-level mechanism describing how chromatin remodeling contributes to the phenotypic switch is not known. We have generated genome-wide maps of 18 histone modifications/variants and variants in both the epithelial and mesenchymal states and quantified patterns of epigenetic changes at gene and enhancer loci. Clusters of these patterns reveal that EMT-related genes and their proximal enhancers are regulated through coordinated patterns of chromatin activation and repression at both gene and enhancer loci. At the cellular level, the remodeling of gene loci translates into a modular protein interaction network that recapitulates EMT-related signaling. Moreover, differentially activated or repressed enhancers are associated with two non-overlapping sets of transcription factors. We propose a chromatin-mediated regulatory feedback loop model where the NFkappaB and AP-1 transcription factors (TFs) bind activated enhancers, that regulate EMT-related genes, which in turn activate signaling pathways upstream of these TFs.
Project description:We have previously shown that Okazaki fragments in Saccharomyces cerevisiae are sized according to the chromatin repeat. Here we demonstrate that nucleosome positioning is rapidly established on newly synthesized DNA. Using deep sequencing, we demonstrate that ATP-dependent chromatin remodeling enzymes, Isw1 and Chd1, collaborate with histone chaperones, such as CAF-1 and Rtt106, to remodel nucleosomes, as they are loaded. Importantly, we find that nucleosome positioning is ultimately specified by select sequence-specific DNA-binding factors, which serve as physical cues for chromatin remodeling. Our results provide a mechanistic understanding of how chromatin structures are replicated in vivo, and show that chromatin structure at gene promoters is rapidly established after DNA replication. Altogether, our data provide evidence for coordinated âloading and remodelingâ of nucleosomes behind the replication fork, in collaboration with packing of nucleosomes against a barrier. 7 samples, including a wild type, are included. All are single-end sequenced via Ion Torrent PGM methodology.