Project description:The roles of retinal cis-regulatory landscape in controlling the expression of gene regulatory networks important for retinogenesis remain poorly understood. Vsx2 is a transcription factor essential for retinal proliferation and bipolar cell differentiation but the molecular mechanisms underlying its developmental roles are unclear. Here, we profiled VSX2 genomic occupancy during mouse retinogenesis, revealing extensive retinal gene regulatory networks associated with Vsx2 during development. We defined an autoregulatory loop in which VSX2 binds and transactivates its own enhancer in association with the transcription factor PAX6 . The Vsx2 regulatory landscape contains elements that are required for Vsx2 expression, retinal proliferation and proper cell type differentiation. We further show that retinae in which the Vsx2 enhancer landscape has been largely deleted suffer a bias toward photoreceptor production. Genomic data indicate that VSX2 occupies cis-regulatory elements nearby genes associated with photoreceptor differentiation and homeostasis in mouse and human retinae, including a conserved region nearby the rod-specifying factor Prdm1. We provide evidence that VSX2 associates with OTX2 and can act to suppress OTX2-dependent enhancer transactivation of Prdm1 enhancer. Taken together, our analyses illuminate important mechanistic insights on how VSX2 is engaged with gene regulatory networks that are essential for retinal proliferation and cell fate acquisition.
Project description:The roles of retinal cis-regulatory landscape in controlling the expression of gene regulatory networks important for retinogenesis remain poorly understood. Vsx2 is a transcription factor essential for retinal proliferation and bipolar cell differentiation but the molecular mechanisms underlying its developmental roles are unclear. Here, we profiled VSX2 genomic occupancy during mouse retinogenesis, revealing extensive retinal gene regulatory networks associated with Vsx2 during development. We defined an autoregulatory loop in which VSX2 binds and transactivates its own enhancer in association with the transcription factor PAX6 . The Vsx2 regulatory landscape contains elements that are required for Vsx2 expression, retinal proliferation and proper cell type differentiation. We further show that retinae in which the Vsx2 enhancer landscape has been largely deleted suffer a bias toward photoreceptor production. Genomic data indicate that VSX2 occupies cis-regulatory elements nearby genes associated with photoreceptor differentiation and homeostasis in mouse and human retinae, including a conserved region nearby the rod-specifying factor Prdm1. We provide evidence that VSX2 associates with OTX2 and can act to suppress OTX2-dependent enhancer transactivation of Prdm1 enhancer. Taken together, our analyses illuminate important mechanistic insights on how VSX2 is engaged with gene regulatory networks that are essential for retinal proliferation and cell fate acquisition.
Project description:The roles of retinal cis-regulatory landscape in controlling the expression of gene regulatory networks important for retinogenesis remain poorly understood. Vsx2 is a transcription factor essential for retinal proliferation and bipolar cell differentiation but the molecular mechanisms underlying its developmental roles are unclear. Here, we profiled VSX2 genomic occupancy during mouse retinogenesis, revealing extensive retinal gene regulatory networks associated with Vsx2 during development. We defined an autoregulatory loop in which VSX2 binds and transactivates its own enhancer in association with the transcription factor PAX6 . The Vsx2 regulatory landscape contains elements that are required for Vsx2 expression, retinal proliferation and proper cell type differentiation. We further show that retinae in which the Vsx2 enhancer landscape has been largely deleted suffer a bias toward photoreceptor production. Genomic data indicate that VSX2 occupies cis-regulatory elements nearby genes associated with photoreceptor differentiation and homeostasis in mouse and human retinae, including a conserved region nearby the rod-specifying factor Prdm1. We provide evidence that VSX2 associates with OTX2 and can act to suppress OTX2-dependent enhancer transactivation of Prdm1 enhancer. Taken together, our analyses illuminate important mechanistic insights on how VSX2 is engaged with gene regulatory networks that are essential for retinal proliferation and cell fate acquisition.
Project description:Super-enhancers comprise of dense transcription factor platforms highly enriched for active chromatin marks. A paucity of functional data led us to investigate their role in the mammary gland, an organ characterized by exceptional gene regulatory dynamics during pregnancy. ChIP-Seq for the master regulator STAT5, the glucocorticoid receptor, H3K27ac and MED1, identified 440 mammary-specific super-enhancers, half of which were associated with genes activated during pregnancy. We interrogated the Wap super-enhancer, generating mice carrying mutations in STAT5 binding sites within its three constituent enhancers. Individually, only the most distal site displayed significant enhancer activity. However, combinatorial mutations showed that the 1,000-fold gene induction relied on all enhancers. Disabling the binding sites of STAT5, NFIB and ELF5 in the proximal enhancer incapacitated the entire super-enhancer, suggesting an enhancer hierarchy. The identification of mammary-specific super-enhancers and the mechanistic exploration of the Wap locus provide insight into the complexity of cell-specific and hormone-regulated genes. ChIP-Seq for STAT5A, GR, H3K27ac, MED1, NFIB, ELF5, RNA Pol II, and H3K4me3 in wild type (WT) mammary tissues at day one of lactation (L1), and ChIP-Seq for STAT5A, GR, H3K27ac, MED1, NFIB, ELF5, and H3K4me3 in WT mammary tissues at day 13 of pregnancy (p13). ChIP-Seq for STAT5A, GR, H3K27a in Wap-delE1a, -delE1b, -delE1c, -delE2 and -delE3 mutant mammary tissues at L1, and ChIP-Seq for NFIB and ELF5 in Wap-delE1b and -delE1c mutant mammary tissues at L1. ChIP-Seq for H3K4me3 in mammary-epthelial cells at p13 and L1. DNase-seq in WT mammary tissues at L1 and DNase-seq in Wap-delE1a, -delE1c, and -delE3 mutant mammary tissues at L1.
Project description:Here we apply integrated epigenomic and transcriptomic profiling to uncover super-enhancer heterogeneity between breast cancer subtypes, and provide clinically relevant biological insights towards TNBC. Using CRISPR/Cas9-mediated gene editing, we identify genes that are specifically regulated by TNBC-specific super-enhancers, including FOXC1 and MET, thereby unveiling a mechanism for specific overexpression of the key oncogenes in TNBC. We also identify ANLN as a novel TNBC-specific gene regulated by super-enhancer. Our studies reveal a TNBC-specific epigenomic landscape, contributing to the dysregulated oncogene expression in breast tumorigenesis.
Project description:Here, we investigate the role of enhancers in myofibroblasts, a cell type that dominates the pathogenesis and progression of tissue fibrosis. We reveal that bromodomain and extra-terminal family members (BETs), an important group of epigenetic readers, are critical for super-enhancer-mediated pro-fibrotic gene expression in hepatic stellate cells (HSCs, lipid-containing liver-specific pericytes), upon activation during liver fibrogenesis give rise to myofibroblasts2-4. We observe significantly enriched localization of BETs to hundreds of super-enhancers associated with genes involved in multiple pro-fibrotic pathways. This unique loading pattern consequentially serves as a molecular mechanism by which BETs modulate pro-fibrotic gene expression in myofibroblasts. Strikingly, suppression of BET-enhancer interaction using small-molecule inhibitors such as JQ1 dramatically blocks activation of HSCs into myofibroblasts and significantly compromises the proliferation of activated HSCs. Identification of BRD2, BRD3, BRD4, PolII, PolIIs2p and PolIIs5p binding sites in human stellate LX2 cells that were treated with DMSO (0.1%) or JQ1 (500nM) for 16 hrs.
Project description:Super-enhancers comprise of dense transcription factor platforms highly enriched for active chromatin marks. A paucity of functional data led us to investigate their role in the mammary gland, an organ characterized by exceptional gene regulatory dynamics during pregnancy. ChIP-Seq for the master regulator STAT5, the glucocorticoid receptor, H3K27ac and MED1, identified 440 mammary-specific super-enhancers, half of which were associated with genes activated during pregnancy. We interrogated the Wap super-enhancer, generating mice carrying mutations in STAT5 binding sites within its three constituent enhancers. Individually, only the most distal site displayed significant enhancer activity. However, combinatorial mutations showed that the 1,000-fold gene induction relied on all enhancers. Disabling the binding sites of STAT5, NFIB and ELF5 in the proximal enhancer incapacitated the entire super-enhancer, suggesting an enhancer hierarchy. The identification of mammary-specific super-enhancers and the mechanistic exploration of the Wap locus provide insight into the complexity of cell-specific and hormone-regulated genes.