Project description:The position of nucleosomes influences DNA accessibility to DNA-binding proteins. Genome-wide nucleosome profiles often report the observation of a canonical nucleosome organization at gene promoters where arrays of well-positioned nucleosomes emanate from nucleosome-depleted regions. It is unclear how this canonical promoter nucleosome organization forms and how it is related to transcription activation and the establishment of histone marks during development. Here we report the genome-wide organization of nucleosomes during zebrafish embryogenesis and show that well-positioned nucleosome arrays appear in thousands of promoters during the activation of the zygotic genome. The formation of canonical promoter nucleosome organization cannot be explained by DNA sequence preference, and is independent of transcription and the presence of RNA polymerase II, but strongly correlates with the presence of Histone H3 Lysine 4 trimethylation (H3K4me3). Our study further suggests that promoter nucleosome structure primes genes to future transcription activation. Together, this study reveals that genome activation but not transcription underlies the organization of nucleosome arrays during early embryogenesis. MNase-seq to generate nucleosome organization in two stages of zebrafish development; two biological replicates for each stage. 7 ChIP-seq experiments in three stages.
Project description:The position of nucleosomes influences DNA accessibility to DNA-binding proteins. Genome-wide nucleosome profiles often report the observation of a canonical nucleosome organization at gene promoters where arrays of well-positioned nucleosomes emanate from nucleosome-depleted regions. It is unclear how this canonical promoter nucleosome organization forms and how it is related to transcription activation and the establishment of histone marks during development. Here we report the genome-wide organization of nucleosomes during zebrafish embryogenesis and show that well-positioned nucleosome arrays appear in thousands of promoters during the activation of the zygotic genome. The formation of canonical promoter nucleosome organization cannot be explained by DNA sequence preference, and is independent of transcription and the presence of RNA polymerase II, but strongly correlates with the presence of Histone H3 Lysine 4 trimethylation (H3K4me3). Our study further suggests that promoter nucleosome structure primes genes to future transcription activation. To determine whether the occlusions are consistent in mammalian pluripotent cells, we performed the same analyses in mouse embryonic stem cells and found similar relationships. MNase-seq to generate nucleosome organization in mouse embryonic stem cell (J1)
Project description:The organization of nucleosomes influences transcriptional activity by controlling accessibility of DNA binding proteins to the genome. Genome-wide nucleosome binding profiles have identified a canonical nucleosome organization at gene promoters, where arrays of well-positioned nucleosomes emanate from nucleosome-depleted regions. The mechanisms of formation and the function of canonical promoter nucleosome organization remain unclear. Here we analyze the genome-wide location of nucleosomes during zebrafish embryogenesis and show that well-positioned nucleosome arrays appear on thousands of promoters during the activation of the zygotic genome. The formation of canonical promoter nucleosome organization is independent of DNA sequence preference, transcriptional elongation, and robust RNA polymerase II (Pol II) binding. Instead, canonical promoter nucleosome organization correlates with the presence of Histone H3 Lysine 4 trimethylation (H3K4me3) and affects future transcriptional activation. These findings reveal that genome activation is central to the organization of nucleosome arrays during early embryogenesis.
Project description:The organization of nucleosomes influences transcriptional activity by controlling accessibility of DNA binding proteins to the genome. Genome-wide nucleosome binding profiles have identified a canonical nucleosome organization at gene promoters, where arrays of well-positioned nucleosomes emanate from nucleosome-depleted regions. The mechanisms of formation and the function of canonical promoter nucleosome organization remain unclear. Here we analyze the genome-wide location of nucleosomes during zebrafish embryogenesis and show that well-positioned nucleosome arrays appear on thousands of promoters during the activation of the zygotic genome. The formation of canonical promoter nucleosome organization is independent of DNA sequence preference, transcriptional elongation, and robust RNA polymerase II (Pol II) binding. Instead, canonical promoter nucleosome organization correlates with the presence of Histone H3 Lysine 4 trimethylation (H3K4me3) and affects future transcriptional activation. These findings reveal that genome activation is central to the organization of nucleosome arrays during early embryogenesis.
Project description:In mammals, retinal damage is followed by Müller glia cell activation and proliferation. While retinal gliosis persists in adult mammals after an insult or disease, some vertebrates, including zebrafish, have the capacity to regenerate. We believe we are the first group to show that gliosis is a fibrotic-like process in mammals’ eyes caused by differential activation of canonical and non-canonical TGFβ signaling pathways.