ABSTRACT: Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:This SuperSeries is composed of the SubSeries listed below. Several co-repressors interact directly with the DNA-binding protein CSL [Su(H) in Drosophila] and are proposed to keep target genes silenced in the absence of Notch activity. To investigate co-repressor activity in the context of this well defined signalling pathway, we analysed the genome-wide binding profile of the best-characterized CSL co-repressor in Drosophila, Hairless, in Kc cells and in wing imaginal discs. The binding profile in wing discs of a second CSL interacting repressor, SMRTER, was also analysed. There was significant overlap between Hairless and Su(H), both in Kc cells and in wing discs, where they were predominantly found in chromatin with active enhancer marks. The Hairless complex was widely present at some Notch regulated enhancers in the wing disc,but no binding was detected at others, indicating that it is not essential for silencing per se. Analysis of target enhancers confirmed differential requirements for Hairless. SMRTER binding significantly overlapped with Hairless, rather than complementing it, and many enhancers were apparently co-bound by both factors. Our analysis indicates that the actions of Hairless and SMRTER gate the enhancers to Notch activity and to Ecdysone signalling respectively, to ensure that the appropriate levels and timing of target gene expression are achieved.
Project description:The conserved Notch pathway functions in diverse developmental and disease-related processes, requiring mechanisms to ensure appropriate target-selection and gene activation in each context. To investigate, we partitioned Drosophila chromatin into different states, based on histone modifications, establishing the preferred chromatin conditions for binding of CSL, the Notch pathway transcription factor. While most histone modifications were unchanged by CSL binding or Notch activation, rapid changes in H3K56 acetylation occurred at Notch regulated-enhancers. This modification extended over large regions, required the histone acetyl-transferase CBP and was independent of transcription. Such rapid changes in H3K56 acetylation are a conserved indicator of enhancer activation, also occurring at mammalian Notch-regulated Hey1 and at Drosophila ecdysone-regulated genes. This core histone modification may therefore underpin the changes in chromatin accessibility needed to promote transcription following signaling activation. Su(H) profile of Kc cells transfected with GFP-Su(H). In total 6 samples, 3 replicates of anti-GFP ChIP and corresponding total input samples in Kc cells.
Project description:The conserved Notch pathway functions in diverse developmental and disease-related processes, requiring mechanisms to ensure appropriate target-selection and gene activation in each context. To investigate, we partitioned Drosophila chromatin into different states, based on histone modifications, establishing the preferred chromatin conditions for binding of CSL, the Notch pathway transcription factor. While most histone modifications were unchanged by CSL binding or Notch activation, rapid changes in H3K56 acetylation occurred at Notch regulated-enhancers. This modification extended over large regions, required the histone acetyl-transferase CBP and was independent of transcription. Such rapid changes in H3K56 acetylation are a conserved indicator of enhancer activation, also occurring at mammalian Notch-regulated Hey1 and at Drosophila ecdysone-regulated genes. This core histone modification may therefore underpin the changes in chromatin accessibility needed to promote transcription following signaling activation. H3K56ac profile of Kc cells in control condition and EGTA treated condition. In total 4 samples, 2 replicates of H3K56ac ChIP in hbss condition and 2 replicates of H3K56ac ChIP in EGTA treated Kc cells.