The chromatin and regulatory properties of pluripotency-associated poised enhancers are conserved in vivo [ChIP-seq]
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ABSTRACT: Transcriptional and phenotypic robustness during development is believed to require complex regulatory landscapes whereby multiple enhancers redundantly control the expression of major cell identity genes. In contrast, we previously described a limited and genetically distinct set of distal regulatory elements, known as poised enhancers (PEs), that control the induction of genes involved in early brain development in a hierarchical and non-redundant manner. Before becoming activated in neural progenitors, PEs are already bookmarked in pluripotent cells with unique chromatin and topological features that could contribute to their privileged regulatory properties. However, since PEs were originally identified and subsequently characterized using embryonic stem cells (ESC) as in an in vitro differentiation system, it is currently unknown whether PEs are functionally conserved in vivo. Here, we generate and mine various types of genomic data to conclusively show that the epigenetic and 3D structural features of PEs are conserved among pluripotent cells both in vitro and in vivo. Furthermore, by genetically disrupting evolutionary conserved PEs in mouse and chicken embryos, we demonstrate that these regulatory elements play essential and non-redundant roles during the induction of major anterior neural genes in vivo.
Project description:Transcriptional and phenotypic robustness during development is believed to require complex regulatory landscapes whereby multiple enhancers redundantly control the expression of major cell identity genes. In contrast, we previously described a limited and genetically distinct set of distal regulatory elements, known as poised enhancers (PEs), that control the induction of genes involved in early brain development in a hierarchical and non-redundant manner. Before becoming activated in neural progenitors, PEs are already bookmarked in pluripotent cells with unique chromatin and topological features that could contribute to their privileged regulatory properties. However, since PEs were originally identified and subsequently characterized using embryonic stem cells (ESC) as in an in vitro differentiation system, it is currently unknown whether PEs are functionally conserved in vivo. Here, we generate and mine various types of genomic data to conclusively show that the epigenetic and 3D structural features of PEs are conserved among pluripotent cells both in vitro and in vivo. Furthermore, by genetically disrupting evolutionary conserved PEs in mouse and chicken embryos, we demonstrate that these regulatory elements play essential and non-redundant roles during the induction of major anterior neural genes in vivo.
Project description:Transcriptional and phenotypic robustness during development is believed to require complex regulatory landscapes whereby multiple enhancers redundantly control the expression of major cell identity genes. In contrast, we previously described a limited and genetically distinct set of distal regulatory elements, known as poised enhancers (PEs), that control the induction of genes involved in early brain development in a hierarchical and non-redundant manner. Before becoming activated in neural progenitors, PEs are already bookmarked in pluripotent cells with unique chromatin and topological features that could contribute to their privileged regulatory properties. However, since PEs were originally identified and subsequently characterized using embryonic stem cells (ESC) as in an in vitro differentiation system, it is currently unknown whether PEs are functionally conserved in vivo. Here, we generate and mine various types of genomic data to conclusively show that the epigenetic and 3D structural features of PEs are conserved among pluripotent cells both in vitro and in vivo. Furthermore, by genetically disrupting evolutionary conserved PEs in mouse and chicken embryos, we demonstrate that these regulatory elements play essential and non-redundant roles during the induction of major anterior neural genes in vivo.
Project description:ABSTRACT: Enhancers are important regulators of gene expression in eukaryotes; however, only a few enhancers have been identified in plants, and the genome-wide identifications are lacking. To investigate enhancers in Arabidopsis thaliana, we analyzed the chromatin landscape, RNA Pol II occupancy, and the polyadenylated and non-polyadenylated Arabidopsis transcriptomes, using exosome-deficient lines to capture stable and unstable transcripts. Here we identified the set of unique >1900 regions, termed Putative Enhancers (PEs), carrying canonical chromatin signatures of metazoan transcriptional enhancers. Almost of PEs are intra-genic and transcriptionally active. Unexpectedly, most of the PE carrying these signatures are associated with the 3′ ends of protein-coding genes, enriched in transcription factor binding, with binding motifs resembling polyadenylation signals, thus linking links two hubs of very different, functionally and mechanistically distinct processes – cleavage/polyadenylation and transcription termination of protein-coding genes with transcriptional activation/regulation of different genes. And may present a novel DNA elements with regulatory potential. Additionally, according to high resolution Arabidopsis Hi-C data 24% of identified PEs interact with other protein-coding genes intrachromosomally, through binding by the same set of transcription factors, supporting the notion of co-regulation of expression between PEs and their targets. We also confirmed that PEs are highly conserved in the recently sequenced 1035 different Arabidopsis accessions.
Project description:Distal enhancers characterized by H3K4me1 mark play critical roles in developmental and transcriptional programs. However, potential roles of specific distal regulatory elements in regulating RNA Polymerase II (Pol II) promoter-proximal pause release remain poorly investigated. Here we report that a unique cohort of jumonji C domain-containing protein 6 (JMJD6) and bromodomain-containing protein 4 (Brd4) co-bound distal enhancers, termed anti-pause enhancers (A-PEs), regulate promoter-proximal pause release of a large subset of transcription units via long-range interactions. Brd4-dependent JMJD6 recruitment on A-PEs mediates erasure of H4R3me2(s), which is directly read by 7SK snRNA, and decapping/demethylation of 7SK snRNA, ensuring the dismissal of the 7SKsnRNA/HEXIM inhibitory complex. The interactions of both JMJD6 and Brd4 with the P-TEFb complex permit its activation and pause release of regulated coding genes. The functions of JMJD6/ Brd4-associated dual histone and RNA demethylase activity on anti-pause enhancers have intriguing implications for these proteins in development, homeostasis and disease. All Gro-seq(s) were designed to reveal the transcriptional targets of JMJD6 and Brd4, and assess the role of JMJD6 and Brd4 in Pol II promoter-proximal pause release. All ChIP-seq(s) were designed to understand the unique features, associated molecular mechanisms and functions of the anti-pause enhancers (A-PEs) discovered in the current study.
Project description:CpG islands (CGIs) represent a unique and widespread genetic feature of vertebrate genomes, being associated with ~70% of all annotated gene promoters. CGIs have been proposed to control transcription initiation by conferring nearby promoters with unique chromatin properties. In addition, there are thousands of distal or orphan CGIs (oCGIs) whose functional relevance and mechanism of action are barely known. Here we show that oCGIs are an essential component of poised enhancers (PEs) that boost their long-range regulatory activity and dictate the responsiveness of their target genes. Using a CRISPR/Cas9 knock-in strategy in mESC, we introduced PEs with or without oCGIs within topological associating domains (TADs) harbouring genes with different types of promoters. By evaluating the chromatin, topological and regulatory properties of the engineered PEs, we uncovered that, rather than increasing their local activation, the oCGI boost the physical and functional communication between PEs and distally located developmental genes. Furthermore, we demonstrate that developmental genes with CpG rich promoters are particularly responsive to PEs and that such responsiveness depends on the presence of oCGI. Therefore, our work unveils a novel role for CGIs as genetic determinants of the compatibility between genes and enhancers, which has major implications for the current understanding of how developmental gene expression programs are deployed as well as for our ability to predict the pathological consequences of human structural variation.
Project description:Dormancy is an essential biological process for the propagation of many life forms through generations and stressful conditions. Early embryos of many mammals are preservable for weeks to months within the uterus under dormancy, which can be induced in vitro through mTOR inhibition. Dormancy features silencing of the genome and abundant heterochromatin formation, which conflicts with the permissive and uncommitted genomic profile of pluripotent cells. Cellular strategies to maintain pluripotency in the fate of this conflict are not known. Here we probed chromatin regulation during embryonic stem cells’ (ESC) entry into dormancy to identify mechanisms that ensure faithful propagation of cellular identity through dormancy. We show a global increase in DNA methylation and loss of chromatin accessibility in dormant ESCs and find that TET DNA demethylases are essential to counteract this trend at key pluripotency regulatory elements, particularly at young LINE1 repeats and active enhancers. Demethylation of these targets by TETs is essential for transcription factor (TF) recruitment and transient chromatin decondensation before hypercompaction. We propose that key regulatory elements are bookmarked coordinately by TETs and TFs in dormancy for maintenance of cellular identity. Perturbation of TET activity compromises embryo survival through dormancy; whereas its enhancement improves survival rates. Our results reveal the first essential chromatin regulator in establishing mammalian embryonic dormancy and pave the way to building its temporal regulatory code in embryonic and adult tissues.
Project description:Genome-wide mapping of transcriptional regulatory elements are essential tools for the understanding of the molecular events orchestrating self-renewal, commitment and differentiation of stem cells. We combined high-throughput identification of nascent, Pol-II-transcribed RNAs by Cap Analysis of Gene Expression (CAGE-Seq) with genome-wide profiling of histones modifications by chromatin immunoprecipitation (ChIP-seq) to map active promoters and enhancers in a model of human neural commitment, represented by embryonic stem cells (ESCs) induced to differentiate into self-renewing neuroepithelial-like stem cells (NESC). We integrated CAGE-seq, ChIP-seq and gene expression profiles to discover shared or cell-specific regulatory elements, transcription start sites and transcripts associated to the transition from pluripotent to neural-restricted stem cell. Our analysis showed that >90% of the promoters are in common between the two cell types, while approximately half of the enhancers are cell-specific and account for most of the epigenetic changes occurring during neural induction, and most likely for the modulation of the promoters to generate cell-specific gene expression programs. Interestingly, the majority of the promoters activated or up-regulated during neural induction have a “bivalent” histone modification signature in ESCs, suggesting that developmentally-regulated promoters are already poised for transcription in ESCs, which are apparently pre-committed to neuroectodermal differentiation. Overall, our study provide a collection of differentially used enhancers, promoters, transcription starts sites, protein-coding and non-coding RNAs in human ESCs and ESC-derived NESCs, and a broad, genome-wide description of promoter and enhancer usage and gene expression programs occurring in the transition from a pluripotent to a neural-restricted cell fate. Investiagtion of promoters usage changes during ESCs neural induction ESCs and NESCs promoter usage profiling by CAGE-seq
Project description:The shape of the human face is largely genetically determined, but the genetic drivers of craniofacial morphology remain poorly understood. In particular, little is known about the contributions of gene regulatory sequences active in the developing face to craniofacial morphology. Here we used a combination of epigenomic profiling, in vivo characterization of more than 200 craniofacial candidate enhancer sequences in transgenic mice, and targeted deletion experiments to examine the role of distant-acting enhancers in craniofacial development. We identified complex regulatory landscapes with thousands of enhancers genome-wide that drive a remarkable spatial complexity of in vivo expression patterns. The ChIP-seq experiments in this entry was the basis for the genome-wide analysis of craniofacial enhancers and served as the source for substantialin vivo characterization via transgenic reporter mice and for enhancer knockout experiments. p300 ChIP-seq experiment on mouse embryonic tissue (e11.5)
Project description:Lineage-specific transcription factors (TFs) operate as master orchestrators of developmental processes by activating select cis-regulatory enhancers and proximal promoters. Direct DNA binding of TFs ultimately drives context-specific recruitment of the basal transcriptional machinery that comprises RNA Polymerase II (RNAPII) and a host of polymerase-associated multiprotein complexes, including the metazoan-specific Integrator complex. Integrator is primarily known to modulate RNAPII processivity and to surveil RNA integrity across coding genes. Here we show an enhancer module of Integrator that directs cell fate specification by promoting epigenetic changes and TF binding at neural enhancers. Depletion of Integrator’s INTS10 upends neural traits and derails cells towards mesenchymal identity. Commissioning of neural enhancers relies on Integrator’s enhancer module, which stabilizes SOX2 binding at chromatin upon exit from pluripotency. We propose Integrator as a functional bridge between enhancers and promoters and a main driver of early development, providing new insight into a growing family of neurodevelopmental syndromes.