Project description:Frequent activation of the co-transcriptional factor YAP is observed in a large number of solid tumors. Activated-YAP associates with enhancer loci via TEAD4-DNA-binding protein, and stimulates cancer aggressiveness. Although thousands of YAP/TEAD4 binding-sites were annotated, their functional importance is unknow. Here, we implemented a genetic approach to uncover functions of YAP/TEAD4-associated enhancers, demonstrated its robustness, and used it to reveal a network of enhancers required for YAP-mediated proliferation. We focused on Enhancer TRAM2, as its target gene TRAM2 showed the strongest expression-correlation with YAP in nearly all tumor types. Interestingly, TRAM2 phenocopied YAP-induced cell proliferation, migration and invasion phenotypes, and correlated with poor patient survival. Mechanistically, we identified FSTL-1 as a major direct client of TRAM2 that is involved in these phenotypes. Thus, TRAM2 is a key novel mediator of YAP-induced oncogenic proliferation and cellular invasiveness.
Project description:The Hippo/YAP signaling pathway is a crucial regulator of tissue growth and stem cell activity.YAP, a transcriptional co-activator and main effector of the pathway, is also a powerful driver of tumorigenesis However, the genetic program regulated by YAP and the mechanism by which YAP controls transcription remains to be fully elucidated. Here, we utilize global chromatin occupancy analyses to demonstrate that robust YAP binding is restricted to a relatively small number of distal regulatory elements in the genome. YAP-occupancy defines a subset of enhancers and super-enhancers with the highest transcriptional outputs. We find that YAP modulates transcription from these elements predominantly by regulating promoter-proximal Polymerase II (PolII) pause release. Mechanistically, YAP physically interacts and recruits the Mediator complex to enhancers, which then allows for recruitment of the CDK9 elongating kinase. Genetic and chemical perturbation experiments demonstrate the requirement for Mediator and CDK9 in YAP-driven phenotypes of overgrowth and tumorigenesis. Our results here uncover the molecular mechanisms employed by YAP to exert its growth and oncogenic functions, and suggest new strategies for intervention.
Project description:The Hippo/YAP signaling pathway is a crucial regulator of tissue growth and stem cell activity.YAP, a transcriptional co-activator and main effector of the pathway, is also a powerful driver of tumorigenesis However, the genetic program regulated by YAP and the mechanism by which YAP controls transcription remains to be fully elucidated. Here, we utilize global chromatin occupancy analyses to demonstrate that robust YAP binding is restricted to a relatively small number of distal regulatory elements in the genome. YAP-occupancy defines a subset of enhancers and super-enhancers with the highest transcriptional outputs. We find that YAP modulates transcription from these elements predominantly by regulating promoter-proximal Polymerase II (PolII) pause release. Mechanistically, YAP physically interacts and recruits the Mediator complex to enhancers, which then allows for recruitment of the CDK9 elongating kinase. Genetic and chemical perturbation experiments demonstrate the requirement for Mediator and CDK9 in YAP-driven phenotypes of overgrowth and tumorigenesis. Our results here uncover the molecular mechanisms employed by YAP to exert its growth and oncogenic functions, and suggest new strategies for intervention.
Project description:The Hippo/YAP signaling pathway is a crucial regulator of tissue growth and stem cell activity.YAP, a transcriptional co-activator and main effector of the pathway, is also a powerful driver of tumorigenesis However, the genetic program regulated by YAP and the mechanism by which YAP controls transcription remains to be fully elucidated. Here, we utilize global chromatin occupancy analyses to demonstrate that robust YAP binding is restricted to a relatively small number of distal regulatory elements in the genome. YAP-occupancy defines a subset of enhancers and super-enhancers with the highest transcriptional outputs. We find that YAP modulates transcription from these elements predominantly by regulating promoter-proximal Polymerase II (PolII) pause release. Mechanistically, YAP physically interacts and recruits the Mediator complex to enhancers, which then allows for recruitment of the CDK9 elongating kinase. Genetic and chemical perturbation experiments demonstrate the requirement for Mediator and CDK9 in YAP-driven phenotypes of overgrowth and tumorigenesis. Our results here uncover the molecular mechanisms employed by YAP to exert its growth and oncogenic functions, and suggest new strategies for intervention.
Project description:The master transcription factors Oct4, Sox2 and Nanog bind enhancer elements and recruit the Mediator co-activator to activate much of the gene expression program of embryonic stem cells (ESCs). We report here that the ESC master transcription factors and Mediator form “super-enhancers” at most genes known to control the pluripotent state, including those encoding the master transcription factors themselves. These super-enhancers consist of extraordinarily large genomic domains occupied by exceptional amounts of Oct4, Sox2, Nanog, Klf4, Esrrb and Mediator. Super-enhancers stimulate considerably higher transcription than typical enhancers in vivo and in reporter vectors. Reduced levels of Oct4 or Mediator cause preferential loss of expression of super-enhancer-associated genes relative to other genes, suggesting how changes in gene expression programs might be accomplished during development. In other more differentiated cells, super-enhancers containing cell-type-specific master transcription factors are also found at genes that define cell identity. These results implicate super-enhancers in the control of mammalian cell identity and differentiation. ChIP-Seq and controls associated with Super-Enhancers in murine cell types
Project description:The master transcription factors Oct4, Sox2 and Nanog bind enhancer elements and recruit the Mediator co-activator to activate much of the gene expression program of embryonic stem cells (ESCs). We report here that these ESC master transcription factors and Mediator form M-bM-^@M-^\super-enhancersM-bM-^@M-^] at most genes that are known to control the pluripotent state, including those encoding the master transcription factors themselves. These super-enhancers consist of extraordinarily large genomic domains occupied by exceptional amounts of Oct4 and Mediator. Super-enhancers stimulate considerably higher transcription than typical enhancers in reporter vectors. ESC differentiation causes preferential loss of expression of super-enhancer -associated genes. Super-enhancers are also found at key cell identity genes in differentiated cells. These results implicate super-enhancers in the control of mammalian cell identity and differentiation and suggest that these elements might generally be used to identify genes that control cell-type specific gene expression programs in many mammalian cells. ChIP-Seq and RNA-seq of Med1 in ZHBTc4 ES during treatment with doxycycline. ChIP-Seq data of Med1 in 38B9 pro-B cells.
Project description:Background—YAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and Results—To identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110β, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. Conclusion—Pik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival. Yap wild type ChIPseq and input
Project description:The master transcription factors Oct4, Sox2 and Nanog bind enhancer elements and recruit the Mediator co-activator to activate much of the gene expression program of embryonic stem cells (ESCs). We report here that the ESC master transcription factors and Mediator form M-bM-^@M-^\super-enhancersM-bM-^@M-^] at most genes known to control the pluripotent state, including those encoding the master transcription factors themselves. These super-enhancers consist of extraordinarily large genomic domains occupied by exceptional amounts of Oct4, Sox2, Nanog, Klf4, Esrrb and Mediator. Super-enhancers stimulate considerably higher transcription than typical enhancers in vivo and in reporter vectors. Reduced levels of Oct4 or Mediator cause preferential loss of expression of super-enhancer-associated genes relative to other genes, suggesting how changes in gene expression programs might be accomplished during development. In other more differentiated cells, super-enhancers containing cell-type-specific master transcription factors are also found at genes that define cell identity. These results implicate super-enhancers in the control of mammalian cell identity and differentiation. Time-course of gene expression following shRNA knockdown of Oct4 and Med12.
Project description:The Hippo/YAP signaling pathway is a crucial regulator of tissue growth and stem cell activity. YAP is also a powerful driver of tumor growth and its nuclear accumulation is frequently observed in human cancer. However, the molecular mechanism employed by YAP to orchestrate transcriptional outputs are undefined. Here, we utilize genomic technologies to demonstrate that YAP occupancy is restricted to a small number of distal regulatory elements highly enriched for superenhancers. Target genes associated with these elements are selectively sensitive to the loss of YAP in cancer cells. YAP directs recruitment of the Mediator complex to activate transcriptional regulation from these enhancers without affecting chromatin organization We also provide in vivo genetic evidence that loss of Mediator rescues YAP-driven cancer cell proliferation and organ overgrowth. Our data provide a molecular mechanism behind YAP-driven tumorigenesis, and highlights transcriptional control as a potential therapeutic strategy for YAP-driven cancers.