Project description:Vertebrate life begins with fertilization, then the zygote genome is activated after transient silencing, termed zygotic genome activation (ZGA). The mechanism of how ZGA initiates is far from clear although it underlay the mystery of totipotency and start of life. The specific property of the minor ZGA implied the possible critical role of ncRNA in the initiation of ZGA. Here we delineated the expression profile of the lncRNAs in the mouse early embryo development and elucidated their critical role in the minor ZGA. LncRNAs showed closer correlation with minor ZGA, they activated earlier than the protein coding genes (PCGs) and suppressed quickly after ZGA. H3K9me3 enrichment prior the ZGA could explain the suspended expression of major ZGA PCGs albeit they possess the PolII pre-configuration. The PolII enriched MuERV-L was found around the TSS of the minor ZGA lncRNAs, and they were responsible for the activation of the minor ZGA lncRNAs and the subsequent embryo development. Our work suggested the MuERV-L mediated minor ZGA lncRNA activation as a critical driver between the epigenetic reprogramming triggered by fertilization and the embryo developmental program, thus provided clues for understanding totipotency and starting of life.
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:We report the analysis of RNA sequencing aimed at understanding the effects induced by the knockdown of SMARCA4 on the expression of repeat and transposable elements in senescent cells. SMARCA4 was initially identified as a target through a genetic screening process designed to locate regulators responsible for upregulating SASP. SMARCA4 is a constituent of the SWI/SNF complex subunit. The findings will help characterise he expression of repeat elements to elucidate the pathway by which SMARCA4 knockdown can promote cytokine expression and Natural Killer cell recruitment.
Project description:We studied functional and structural features of mouse and human SINE repeat elements-derived RNAs in SINEUP long non-coding RNAs which upregulate the translation of the target protein coding gene. To check the interaction of functional SINE RNAs with ribosomal RNAs, we created PARIS2 (psoralen analysis of RNA interactions and structures) libraries from SINEUP (with embedded mouse SINEB2 or human FRAM repeat) and the target sense GFP plasmids co-transfected human cells.
Project description:5-methylcytosine (5mC) is an established epigenetic mark in vertebrate genomic DNA, but whether its oxidation intermediates formed during TET-mediated DNA demethylation possess an instructive role of their own that is also physiologically relevant remains unresolved. Here, we reveal a 5-formylcytosine (5fC) nuclear chromocenter, which transiently forms during zygotic genome activation (ZGA) in Xenopus and mouse embryos. We identify this chromocenter as the perinucleolar compartment, a structure associated with RNA Pol III transcription. In Xenopus embryos, 5fC is highly enriched on Pol III target genes activated at ZGA, notably at oocyte-type tandem arrayed tRNA genes. By manipulating Tet and Tdg enzymes, we show that 5fC is required as a regulatory mark to promote Pol III recruitment as well as tRNA expression. Concordantly, 5fC modification of a tRNA transgene enhances its expression in vivo. The results establish 5fC as an activating epigenetic mark during zygotic reprogramming of Pol III gene expression.
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.