Project description:Gene expression is controlled by sequence-specific transcription factors (TFs), which bind to regulatory sequences in DNA. The degree to which the arrangement of motif sites within regulatory elements determines their function remains unclear. Here, we show that the positional distribution of TF motif sites within NDRs fall into six distinct classes. These patterns are highly consistent across cell types, and bring together factors that have similar functional and binding properties. Furthermore, the position of motif sites appears to be related to their known functions. Our results suggest TFs play distinct roles in forming a functional enhancer, facilitated by their position within a regulatory sequence.
Project description:Gene transcription in animals involves the assembly of the RNA polymerase II complex at core promoters and its cell type-specific activation by genomic enhancers that can be located more distally. However, how ubiquitous expression of housekeeping genes is achieved has remained less clear. In particular, it is unknown whether ubiquitously active enhancers exist and how developmental and housekeeping gene regulation is separated. An attractive hypothesis is that different types of core promoters might exhibit an intrinsic specificity towards certain types of enhancers. Here, we show that thousands of enhancers in D. melanogaster S2 cells and ovarian somatic cells (OSCs) exhibit a marked specificity towards one of two core promoters M-bM-^@M-^S one derived from a ubiquitously expressed ribosomal protein gene and another from a developmentally regulated transcription factor. Enhancers that activate the housekeeping core promoter are functional across the two different cell types, while developmental enhancers exhibit strong cell type specificity. Both enhancer classes differ in their overall genomic distribution, the functions of neighbouring genes,these genesM-bM-^@M-^Y core promoter elements, as well as the associated factors. Our results provide evidence for a sequence-encoded enhancer-core promoter specificity that separates developmental and housekeeping gene regulatory programs for thousands of enhancers and their target genes across the entire genome. STARR-seq was performed in S2 and OSC cells using two core promoters each representing housekeeping and developmental transcription programs. Data for housekeeping promoters (hkCP) are presented in this series; Data for developmental core promoters (dCP) samples are presented in GSE40739.
Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell type-specific gene expression programs; however, the potential that there are pre-established enhancers in different functional classes that permit alternative signal-dependent transcriptional responses has remained unexplored. Here we present evidence that cell lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), acting at structurally- and functionally-distinct classes of pre-established enhancers, thus licensing specific signal-activated responses while restricting others. Consequently, FoxA1 down-regulation, an unfavorable prognostic sign in advanced prostate tumors, causes a massive switch in AR binding from one functional class of enhancers to another, with a parallel switch in levels of enhancer-templated non-coding RNAs (eRNAs) revealed by the global run-on assay (GRO-seq), which documents the dramatic reprogramming of the hormonal response. The molecular basis for this switch lies in the release of FoxA1-mediated restriction of AR binding to the new enhancer class with no apparent nucleosome remodeling, which is required for stimulating their eRNA transcription and/or enhancing enhancer:promoter looping and gene activation. Together, these findings reveal a large repository of pre-determined enhancers in the human genome that can be dynamically tuned to induce their transcription and activation of alternative gene expression programs, which may underlie many sequential gene expression events in development or during disease progression. ChIP-Seq, Gro-Seq, and gene expression profiling was performed in LNCaP cells with hormone treatment and siRNA against FoxA1. Gene expression profiling data presented here.
Project description:Single cell qPCR analysis identified two prominent expression signatures within the planarian stem cells, the neoblasts. RNAi against zinc finger protein zfp-1 results in elimination of one of the two classes.
Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell type-specific gene expression programs; however, the potential that there are pre-established enhancers in different functional classes that permit alternative signal-dependent transcriptional responses has remained unexplored. Here we present evidence that cell lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), acting at structurally- and functionally-distinct classes of pre-established enhancers, thus licensing specific signal-activated responses while restricting others. Consequently, FoxA1 down-regulation, an unfavorable prognostic sign in advanced prostate tumors, causes a massive switch in AR binding from one functional class of enhancers to another, with a parallel switch in levels of enhancer-templated non-coding RNAs (eRNAs) revealed by the global run-on assay (GRO-seq), which documents the dramatic reprogramming of the hormonal response. The molecular basis for this switch lies in the release of FoxA1-mediated restriction of AR binding to the new enhancer class with no apparent nucleosome remodeling, which is required for stimulating their eRNA transcription and/or enhancing enhancer:promoter looping and gene activation. Together, these findings reveal a large repository of pre-determined enhancers in the human genome that can be dynamically tuned to induce their transcription and activation of alternative gene expression programs, which may underlie many sequential gene expression events in development or during disease progression. ChIP-Seq, Gro-Seq, and gene expression profiling was performed in LNCaP cells with hormone treatment and siRNA against FoxA1 ChIP-Seq and Gro-Seq data presented here. Supplementary file GroSeq.denovo.transcripts.hg18.bed represents analysis using GSM686948-GSM686950.
Project description:Gene transcription in animals involves the assembly of the RNA polymerase II complex at core promoters and its cell type-specific activation by genomic enhancers that can be located more distally. However, how ubiquitous expression of housekeeping genes is achieved has remained less clear. In particular, it is unknown whether ubiquitously active enhancers exist and how developmental and housekeeping gene regulation is separated. An attractive hypothesis is that different types of core promoters might exhibit an intrinsic specificity towards certain types of enhancers. Here, we show that thousands of enhancers in D. melanogaster S2 cells and ovarian somatic cells (OSCs) exhibit a marked specificity towards one of two core promoters – one derived from a ubiquitously expressed ribosomal protein gene and another from a developmentally regulated transcription factor. Enhancers that activate the housekeeping core promoter are functional across the two different cell types, while developmental enhancers exhibit strong cell type specificity. Both enhancer classes differ in their overall genomic distribution, the functions of neighbouring genes,these genes’ core promoter elements, as well as the associated factors. Our results provide evidence for a sequence-encoded enhancer-core promoter specificity that separates developmental and housekeeping gene regulatory programs for thousands of enhancers and their target genes across the entire genome.
Project description:Single cell qPCR analysis identified two prominent expression signatures within the planarian stem cells, the neoblasts. RNAi against zinc finger protein zfp-1 results in elimination of one of the two classes. Worms were treated with RNAi by feeding. X1 or X2 cells were isolated by FACS, or blastemas were dissected. mRNA libraries were sequenced.
Project description:The large antigen receptor (AgR) loci in T and B lymphocytes have many bound CTCF sites, most of which are only occupied in lymphocytes, while only the CTCF sites at the far end of each locus near enhancers or J genes tend to be bound in non-lymphoid cells also. However, despite the generalized lymphocyte restriction of CTCF binding in AgR loci, the Igκ locus is the only locus which also shows significant lineage-specificity (T vs. B cells) and developmental stage-specificity (pre-B, not pro-B) in CTCF binding. Cohesin is often bound at the same sites as CTCF, and cohesin is thought to create long range chromatin contacts by loop extrusion, with its translocation stopped by convergently oriented CTCF sites. Importantly, cohesin binding shows greater lineage- and stage- specificity than CTCF at most loci, thus providing more specificity to the CTCF/cohesin loops in AgR loci. Since all the CTCF sites within the large V portions of the Igh and TCRβ loci have the same orientation, this suggests either a lack of requirement for convergent CTCF sites creating loops, or indicates an absence of any loops between CTCF sites within the V region portion of those loci but only loops to the convergent sites at the D‐J‐enhancer end of each locus. The V region portions of the Igκ and TCRα δ loci, in contrast, have CTCF sites in both orientations, providing many options for creating CTCF-mediated loops throughout the loci. The immune system may have developed unique utilization of CTCF sites to generate lymphocyte-specific long-range loops to facilitate the formation of diverse antigen receptor repertoires.