NAD+-dependent histone deacetylase SIRT1 in the process of oogenesis, fertilization and early embryonic development

SIRT1 is a histone deacetylase from the sirtuin family that affects epigenetic and non- epigenetic targets. We can assume that the known SIRT1 substrates are involved in the regulation of gametogenesis and early embryonic development. Our hypotheses say SIRT1 is present in oocytes and early embryos and it plays a physiological role in oocyte maturation, fertilization and early embryonic development. A mouse model of a conditional knock-out line producing Sirt1-deficient oocytes was developed to verify our hypotheses. Oocytes and embryos were analyzed for SIRT1, its selected substrates and other markers by immunocytochemistry. We found out that the presence of SIRT1 contributes to oocyte quality through modulation of the chromatin histone code and stabilization of the spindle. Furthermore, the purely maternal origin of SIRT1 presents in both zygote pronuclei. Last but not least we discovered a significant effect of SIRT1 on early embryonic development, probably mainly due to its role in the activation of the embryonic genome. The results confirm our hypothesis that SIRT1 is present in oocytes and embryos mainly around chromatin. The results show that SIRT1 is a maternal factor determining oocyte quality and it is necessary for the embryonic genome activation