Project description:Pigs are important animals for agricultural and biomedical research, and its assisted reproductive technologies are urgently needed to be improved. Determining the underlying mechanism of epigenetic reprogramming in the early stage of preimplantation embryos derived from in vitro fertilization (IVF), parthenogenesis (PA) and androgenesis (AG), will not only contribute to assisted reproduction technologies of pigs but also will shed light into early human development. We generated 3D chromatin profiles for pig somatic cells, IVF, PA and AG preimplantation embryos. We found that the chromosomes in the pig preimplantation embryos are enriched for superdomains, i.e., the larger than 10M compartment domains, which are much rarer in mice. Wheras, p(s) curves, compartments and TADs, are largely conserved in somatic cells, and are gradually establishing during preimplantation embryogenesis. In the uniparental pig embryos, the establishment of chromatin architecture was highly asynchronized at all levels from IVF embryos, and a remarkably strong decompartmentalization was observed during zygotic genome activation (ZGA). Finally, chromosomes originating from oocytes always establish TADs faster than chromosomes originating from sperm, both before and during ZGA.
Project description:During early vertebrate development, a large number of noncoding RNAs are maternally inherited or expressed upon activation of zygotic transcription. The exact identity, expression levels, and function during early vertebrate development for most of these noncoding RNAs remains largely unknown. miRNAs (microRNAs) and piRNAs (piwi-interacting RNAs) are two classes of small non-coding RNAs that play important roles in gene regulation during early embryonic development. Here, we utilized Illumina next generation sequencing technology to determine temporal expression patterns for both miRNAs and piRNAs during four distinct stages of early vertebrate development using zebrafish as a model system. For miRNAs, the expression patterns for 192 known miRNAs and 12 novel miRNAs within 123 different miRNA families were determined. Significant sequence variation was observed at the 5' and 3' ends of miRNAs with a large number of extra nucleotides added in a non-template directed manner. We also identified a large and diverse set of piRNAs expressed during early development, far beyond that expected if piRNA expression is restricted to germ cells. Our analyses represent the deepest investigation to date of small RNA expression during early vertebrate development and suggest important novel functions for small RNAs during embryogenesis. Identify the expression of small RNAs in zebrafish embryos of four different developmental stages using high through-put sequencing
Project description:Vertebrate embryos achieve developmental competency during zygotic genome activation (ZGA) by establishing chromatin states that silence yet poise developmental genes for subsequent lineage-specific activation. Here, we reveal how developmental gene poising is established de novo in preZGA zebrafish embryos. Poising is established at promoters and enhancers that initially contain open/permissive chromatin with ‘Placeholder’ nucleosomes (bearing H2A.Z, H3K4me1, and H3K27ac), and DNA hypomethylation. Silencing is initiated by the recruitment of Polycomb Repressive Complex 1 (PRC1), and H2Aub1 deposition by catalytic Rnf2 during preZGA and ZGA stages. During postZGA, H2Aub1 enables Aebp2-containing PRC2 recruitment and H3K27me3 deposition. Notably, preventing H2Aub1 (via Rnf2 inhibition) eliminates recruitment of Aebp2-PRC2 and H3K27me3, and elicits transcriptional upregulation of certain developmental genes during ZGA. However, upregulation is independent of H3K27me3 – establishing H2Aub1 as the critical silencing modification at ZGA. Taken together, we reveal the logic and mechanism for establishing poised/silent developmental genes in early vertebrate embryos.
Project description:Vertebrate embryos achieve developmental competency during zygotic genome activation (ZGA) by establishing chromatin states that silence yet poise developmental genes for subsequent lineage-specific activation. Here, we reveal how developmental gene poising is established de novo in preZGA zebrafish embryos. Poising is established at promoters and enhancers that initially contain open/permissive chromatin with ‘Placeholder’ nucleosomes (bearing H2A.Z, H3K4me1, and H3K27ac), and DNA hypomethylation. Silencing is initiated by the recruitment of Polycomb Repressive Complex 1 (PRC1), and H2Aub1 deposition by catalytic Rnf2 during preZGA and ZGA stages. During postZGA, H2Aub1 enables Aebp2-containing PRC2 recruitment and H3K27me3 deposition. Notably, preventing H2Aub1 (via Rnf2 inhibition) eliminates recruitment of Aebp2-PRC2 and H3K27me3, and elicits transcriptional upregulation of certain developmental genes during ZGA. However, upregulation is independent of H3K27me3 – establishing H2Aub1 as the critical silencing modification at ZGA. Taken together, we reveal the logic and mechanism for establishing poised/silent developmental genes in early vertebrate embryos.
Project description:The transcriptional events driving specification of the kidney have been well characterized. However, it remains undetermined how initial kidney field size is established, patterned, and proportioned. Lhx1 is a transcription factor expressed in the kidney anlage and is required for specification of the kidney field, but few Lhx1 interacting cofactors or downstream targets have been identified. By tandem-affinity purification, we isolated Furry (FRY), a multifunctional protein that acts as a transcriptional co-repressor of microRNAs. We found that Xenopus embryos depleted of fry exhibit loss of the kidney field, phenocopying the lhx1 depleted animals. In addition, we demonstrated synergism between Fry and Lhx1, identified candidate microRNAs regulated by the pair, and confirmed these microRNA clusters influence specification of the kidney field. Therefore, our data shows that a tissue-specific transcription factor, Lhx1, interacts with a broadly expressed microRNA repressor, Fry, to establish the kidney field.