Project description:Translation of maternal mRNAs is detected before transcription of zygotic genes and is essential for mammalian embryo development. How certain maternal mRNAs are selected for translation instead of degradation and how this burst of translation affects zygotic genome activation remains unknown. Using gene-edited mice, we document that the oocyte-specific eukaryotic translation initiation factor 4E family member 1b (eIF4E1b) is the regulator of maternal mRNA expression that ensures subsequent reprogramming of the zygotic genome. In oocytes, eIF4E1b binds to transcripts encoding translation machinery proteins, chromatin remodelers and reprogramming factors to promote their translation in zygotes and protect them from degradation. The protein products are thought to establish an open chromatin landscape in one-cell zygotes to enable transcription of genes required for cleavage stage development. Our results define a program for rapid resetting of the zygotic epigenome that is regulated by maternal mRNA expression and provides new insights into the mammalian maternal-to-zygotic transition.
Project description:Translation of maternal mRNAs is detected before transcription of zygotic genes and is essential for mammalian embryo development. How certain maternal mRNAs are selected for translation instead of degradation and how this burst of translation affects zygotic genome activation remains unknown. Using gene-edited mice, we document that the oocyte-specific eukaryotic translation initiation factor 4E family member 1b (eIF4E1b) is the regulator of maternal mRNA expression that ensures subsequent reprogramming of the zygotic genome. In oocytes, eIF4E1b binds to transcripts encoding translation machinery proteins, chromatin remodelers and reprogramming factors to promote their translation in zygotes and protect them from degradation. The protein products are thought to establish an open chromatin landscape in one-cell zygotes to enable transcription of genes required for cleavage stage development. Our results define a program for rapid resetting of the zygotic epigenome that is regulated by maternal mRNA expression and provides new insights into the mammalian maternal-to-zygotic transition.
Project description:Translation of maternal mRNAs is detected before transcription of zygotic genes and is essential for mammalian embryo development. How certain maternal mRNAs are selected for translation instead of degradation and how this burst of translation affects zygotic genome activation remains unknown. Using gene-edited mice, we document that the oocyte-specific eukaryotic translation initiation factor 4E family member 1b (eIF4E1b) is the regulator of maternal mRNA expression that ensures subsequent reprogramming of the zygotic genome. In oocytes, eIF4E1b binds to transcripts encoding translation machinery proteins, chromatin remodelers and reprogramming factors to promote their translation in zygotes and protect them from degradation. The protein products are thought to establish an open chromatin landscape in one-cell zygotes to enable transcription of genes required for cleavage stage development. Our results define a program for rapid resetting of the zygotic epigenome that is regulated by maternal mRNA expression and provides new insights into the mammalian maternal-to-zygotic transition.
Project description:Translation of maternal mRNAs is detected before transcription of zygotic genes and is essential for mammalian embryo development. How certain maternal mRNAs are selected for translation instead of degradation and how this burst of translation affects zygotic genome activation remain unknown. Using gene-edited mice, we document that the oocyte-specific eukaryotic translation initiation factor 4E family member 1b (eIF4E1b) is the regulator of maternal mRNA expression that ensures subsequent reprogramming of the zygotic genome. In oocytes, eIF4E1b binds to transcripts encoding translation machinery proteins, chromatin remodelers, and reprogramming factors to promote their translation in zygotes and protect them from degradation. The protein products are thought to establish an open chromatin landscape in one-cell zygotes to enable transcription of genes required for cleavage stage development. Our results define a program for rapid resetting of the zygotic epigenome that is regulated by maternal mRNA expression and provide new insights into the mammalian maternal-to-zygotic transition. This SuperSeries is composed of the SubSeries listed below.
Project description:Translation of maternal mRNAs is detected before transcription of zygotic genes and is essential for mammalian embryo development. How certain maternal mRNAs are selected for translation instead of degradation and how this burst of translation affects zygotic genome activation remains unknown. Using gene-edited mice, we document that the oocyte-specific eukaryotic translation initiation factor 4E family member 1b (eIF4E1b) is the regulator of maternal mRNA expression that ensures subsequent reprogramming of the zygotic genome. In oocytes, eIF4E1b binds to transcripts encoding translation machinery proteins, chromatin remodelers and reprogramming factors to promote their translation in zygotes and protect them from degradation. The protein products are thought to establish an open chromatin landscape in one-cell zygotes to enable transcription of genes required for cleavage stage development. Our results define a program for rapid resetting of the zygotic epigenome that is regulated by maternal mRNA expression and provides new insights into the mammalian maternal-to-zygotic transition.
Project description:Maternal-to-zygotic transition (MZT) is a conserved and fundamental process during which the maternal environment of oocyte transits to the zygotic genome driven expression program, and terminally differentiated oocyte and sperm are reprogrammed to totipotency. Metaphase II (MII) oocytes and zygotes (one-cell embryo) serve as the mature oocyte and the initiation of pre-implantation embryo development respectively, and characterizing their molecular landscapes at protein levels plays an important role in uncovering MZT and zygotic genome activation (ZGA )in mammals. Here we used an ultrasensitive proteomic approach to depict an in-depth landscape for the very early stage of mouse MZT.
Project description:How the parental genomes of the very specialized sperm and oocyte cells are remodelled upon fertilization to confer totipotency has remained a tantalizing open questions. Indeed, in the case of mammals, the parental genomes undergo dramatic reprogramming upon fertilization, including differential dynamics of histone post-translational modifications. The roles of histone modifying enzymes in this process, which are maternally provided, are only just starting to emerge. Here, we explore the function of the oocyte inherited pool of Lsd1/Kdm1a, which encodes a histone H3K4 and K9 demethylase, during early mouse development. Maternal deficiency of Lsd1/Kdm1a results in developmental arrest by the two-cell stage, associated with dramatic and stepwise alterations in H3K9 and H3K4 methylation patterns depending on its demethylase activity. At the transcriptional level, two major changes occur. On one hand, switch from maternal-to-zygotic program fails to be induced. On the other hand, LINE-1 retrotransposons are not properly silenced, along with evidences for increased LINE-1 activity. We propose that Lsd1/Kdm1a is involved in the correct establishment of epigenetic information harboured by histones and is involved in the initiation of new pattern of genome expression driving early mouse development and preserving genome integrity
Project description:How the parental genomes of the very specialized sperm and oocyte cells are remodelled upon fertilization to confer totipotency has remained a tantalizing open questions. Indeed, in the case of mammals, the parental genomes undergo dramatic reprogramming upon fertilization, including differential dynamics of histone post-translational modifications. The roles of histone modifying enzymes in this process, which are maternally provided, are only just starting to emerge. Here, we explore the function of the oocyte inherited pool of Lsd1/Kdm1a, which encodes a histone H3K4 and K9 demethylase, during early mouse development. Maternal deficiency of Lsd1/Kdm1a results in developmental arrest by the two-cell stage, associated with dramatic and stepwise alterations in H3K9 and H3K4 methylation patterns depending on its demethylase activity. At the transcriptional level, two major changes occur. On one hand, switch from maternal-to-zygotic program fails to be induced. On the other hand, LINE-1 retrotransposons are not properly silenced, along with evidences for increased LINE-1 activity. We propose that Lsd1/Kdm1a is involved in the correct establishment of epigenetic information harboured by histones and is involved in the initiation of new pattern of genome expression driving early mouse development and preserving genome integrity
Project description:Using a mouse model of human MLL-AF9 leukemia, we identified the lysine-specific demethylase KDM1A (LSD1 or AOF2) as an essential regulator of leukemia stem cell (LSC) potential. KDM1A acts at genomic loci bound by MLL-AF9 to sustain expression of the associated oncogenic program, thus preventing differentiation and apoptosis. In vitro and in vivo pharmacologic targeting of KDM1A using tranylcypromine analogues active in the nanomolar range phenocopied Kdm1a knockdown in both murine and primary human AML cells exhibiting MLL translocations. By contrast, the clonogenic and repopulating potential of normal hematopoietic stem and progenitor cells was spared. Our data establish KDM1A as a key effector of the differentiation block in MLL leukemia which may be selectively targeted to therapeutic effect. To investigate the effects of Kdm1a KD on histone modifications, we performed chromatin immunoprecipitation followed by next-generation sequencing (ChIP-Seq) in control and Kdm1a KD MLL-AF9 AML cells for dimethyl-H3K4 and dimethyl-H3K9, as well as for trimethyl-H3K4 and trimethyl-H3K9. Dimethyl-H3K4 and dimethyl-H3K9 are targeted for demethylation by KDM1A. For each of these histone modifications, we compared the mean ChIP-Seq signal across and around protein coding genes bound by the MLL-AF9 oncoprotein (Bernt et al., 2011) with the mean signal from genes not bound by MLL-AF9 expressed at high, middle or low levels.