Project description:Purpose: Find out the consequences of Sox19b binding to the nucleosome distribution after ZGA Methods: MNase-seq of WT and MZsox19b mutant zebrafish embryos at dome stage, building up nucleosome occupancy profiles Results:Maternal Sox19b is involved in the nucleosome displacement from HNARs at the zygotic genome activation. Conclusions: Nucleosome clearance by maternal Sox19b is essential for proper onset and timing of gastrulation.
Project description:Upon fertilization, maternal factors direct development in a transcriptionally silent embryo. At the maternal-to-zygotic transition (MZT), a universal step in animal development, unknown maternal factors trigger zygotic genome activation (ZGA). In zebrafish, ZGA is required for gastrulation and clearance of maternal mRNAs, which is achieved in part by the conserved microRNA miR-430. However, the precise factors that activate the zygotic program remain largely unknown. Here we show that Nanog, Pou5f1 and SoxB1 are required for genome activation in zebrafish. We identified several hundred genes directly activated by maternal factors, thus constituting the first wave of zygotic transcription in zebrafish. Ribosome profiling in the pre-MZT embryo revealed that nanog, sox19b and pou5f1 are the most highly translated transcription factor mRNAs. Combined loss of function for Nanog, SoxB1 and Pou5f1 resulted in developmental arrest prior to gastrulation, and a failure to activate >75% of zygotic genes. Furthermore, we found that Nanog binds the miR-430 locus and together with Pou5f1 and SoxB1 initiate miR-430 expression and activity. Our results demonstrate that maternal Nanog, Pou5f1 and SoxB1 are required to initiate the zygotic developmental program and in turn trigger the clearance of the maternal program by activating miR-430 expression. Wild type and loss-of-function total mRNA sequencing of embryonic transcriptomes pre- and post-MZT; ribosome profiling pre-MZT
Project description:Upon fertilization, maternal factors direct development in a transcriptionally silent embryo. At the maternal-to-zygotic transition (MZT), a universal step in animal development, unknown maternal factors trigger zygotic genome activation (ZGA). In zebrafish, ZGA is required for gastrulation and clearance of maternal mRNAs, which is achieved in part by the conserved microRNA miR-430. However, the precise factors that activate the zygotic program remain largely unknown. Here we show that Nanog, Pou5f1 and SoxB1 are required for genome activation in zebrafish. We identified several hundred genes directly activated by maternal factors, thus constituting the first wave of zygotic transcription in zebrafish. Ribosome profiling in the pre-MZT embryo revealed that nanog, sox19b and pou5f1 are the most highly translated transcription factor mRNAs. Combined loss of function for Nanog, SoxB1 and Pou5f1 resulted in developmental arrest prior to gastrulation, and a failure to activate >75% of zygotic genes. Furthermore, we found that Nanog binds the miR-430 locus and together with Pou5f1 and SoxB1 initiate miR-430 expression and activity. Our results demonstrate that maternal Nanog, Pou5f1 and SoxB1 are required to initiate the zygotic developmental program and in turn trigger the clearance of the maternal program by activating miR-430 expression.
Project description:Absence of Sox3 in mice only results in subtle phenotype, presumably due to the rescue effects from the family members, SOXB1, which consist of Sox1, Sox2 and Sox3. Obvious defect in Sox3-KO mice is seen only in the testes where Sox1 and Sox2 are not co-expressed. The genetic dysregulation underlying this testis defects is unknown. We also hypothesize that this genetic dysregulation can be rescued by the other SOXB1 members. We performed microarray analysis to compare Sox3-KO mouse testes with the WT. We also generated Sox3-Sox2KI mice in which the Sox3 ORF is replaced with Sox2 ORF. Microarray was also performed to these knock-in testis samples to find out whether Sox2 can rescue genetic dysregulation resulting from the absence of Sox3.
Project description:Here we investigate a functional role for SoxB1 transcription factors, Sox2 and Sox3, on the transient embryonic cell population, the neural plate border. We find through gain/loss-of-function studies necessary for neural plate border cells to become neural crest cells. and genomics experiments (ChIP-seq and RNA-seq) that SoxB1 transcription factors directly promote neural plate border formation. and that down-regulation of SoxB1 expression is
Project description:Here we investigate a functional role for SoxB1 transcription factors, Sox2 and Sox3, on the transient embryonic cell population, the neural plate border. We find through gain/loss-of-function studies necessary for neural plate border cells to become neural crest cells. and genomics experiments (ChIP-seq and RNA-seq) that SoxB1 transcription factors directly promote neural plate border formation. and that down-regulation of SoxB1 expression is
Project description:Purpose: Find out the consequences of Pou5f3/Oct4 and Nanog binding to the nucleosome distribution before and after Zygotic Genome Activation Methods: MNase-seq of the wild-type(WT), Pou5f3 (MZspg) and Nanog (MZnanog) mutant zebrafish embryos at 512-cell stage and dome stage. Results: Nanog, Sox19b and Pou5f3 bind to the High Nucleosome Affinity Regions (HNARs). HNARs are spanning over 600 bp, featuring high in vivo and predicted in vitro nucleosome occupancy and high predicted propeller twist DNA shape value. We suggest a two-step model, where the same intrinsic DNA properties of HNAR promote both high nucleosome occupancy and differential binding of TFs. In the first step, already prior to ZGA, Pou5f3 and Nanog reduce nucleosome occupancy on HNARs genome-wide. In the second step, Nanog and Pou5f3/SoxB1 complex maintain open chromatin state on the subset of HNARs, acting synergistically. Nanog binds to the HNAR center, while the Pou5f3/SoxB1 complex stabilizes the flanks.
Project description:Gastrulation is a milestone event of embryonic development, during which germ layers are specified and reassigned into the body plan. Due to the inaccessibility in vivo at this stage and the ethical limitations, gastrulation currently remains a mystery in primates. Here, we report the establishment of an in vitro system to culture cynomolgus monkey embryos after up to 20 days to develop beyond the initiation of gastrulation. The histology, immunostaining and single cell sequencing results showed that the in vitro cultured embryos largely recapitulated the key events of early post-implantation development, and initiated gastrulation in primates. Considering the high similarities between monkeys and humans, this system will provide a unique platform for the investigations of human early post-implantation development at physiological, pathological and environmental conditions.