CANCELLED: PI Seminar: Changes of Activity of APC/C During Transition from Oocytes into Early Embryos

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Abstract

Changes of Activity of APC/C During Transition from Oocytes into Early Embryos

Adela Horakova^{1, 2}, Lenka Radonova^{1, 2}, Marketa Konecna^{1, 2} and Martin Anger^{1, 2}

¹CEITEC, Veterinary Research Institute, Brno, Czech Republic

²Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov

Early development in mammals is characterized by dramatic events, such as meiosis and production of haploid gametes, fertilization initiating transition from meiosis into mitosis, and early cleavage cycles of blastomeres in newly formed embryo, causing rapid reduction of cell size. All these events have remarkable impact on regulation of the cell cycle. Moreover, during meiosis and the first embryonic cleavage cycles, cells are transcriptionally silent, which renders regulated translation, posttranslational modifications and proteolysis essential for controlling the cell cycle and chromosome segregation. Mammalian female germ cells, as well as blastomeres of early embryos, also frequently suffer from aneuploidy that is a leading cause of failure of early development, and it is therefore vital to obtain better understanding of the cell cycle regulatory mechanisms during this period. In our study, we focused on the maintenance of expression of cell cycle regulatory proteins, such as cyclins and securin, during the period of transcriptional silencing. Our results show that the levels of these proteins, during both meiotic divisions and in early mitoses, exhibit surprising fluctuations, which could be explained by involvement of APC/C, not only in their targeting during metaphase to anaphase transition, but also in maintaining their expression levels before division.  Funding: This work was supported by the Czech Science Foundation project 20-25850S and Grant RO0518 of the Ministry of Agriculture of the Czech Republic.