SIRT1 was detected by adapting the above protocol for mouse monoclonal antibody clone 1F3 (ab104833, Abcam). em P /em ??0.05). Stimulation of SIRT1 activity coincided with fluorometric signal intensity of ooplasmic ubiquitin ligase MDM2, a known substrate of SIRT1 and known limiting factor of epigenome remodeling. Conclusions We conclude that SIRT1 modulates zygotic histone code, obviously through direct deacetylation and via non-histone targets resulting in increased H3K9me3. These changes in zygotes lead to more successful pre-implantation embryonic Mirk-IN-1 development and, indeed, the specific SIRT1 activation due to BML-278 is beneficial for in vitro embryo production and blastocyst achievement. Electronic supplementary material The online version of this article (10.1186/s40104-017-0214-0) contains Mirk-IN-1 supplementary material, which is available to authorized users. strong class=”kwd-title” Keywords: Embryonic development, Epigenetics, H3K9 methylation, SIRT1, Sirtuin Background Correct formation of maternal and paternal pronuclei in the fertilized mammalian oocyte, the zygote, is required for the first mitotic cell cycle, subsequent zygotic genome activation and successful development of early embryo [1, 2]. Many events, such as protamine-histone replacement [3, 4], protein recycling through ubiquitin-proteasome system (UPS) [5, 6] and Mirk-IN-1 correct establishment of euchromatin and heterochromatin [7, 8], lead to genome-wide alterations required for the biogenesis of pronuclei. In addition to these essential genomic and cellular events, pronuclei undergo epigenetic changes, i.e. DNA methylation Mirk-IN-1 as well as histone methylation and acetylation, collectively termed the histone code establishment [9C13]. Epigenetic changes in the early zygote include DNA demethylation in both the maternal and paternal pronucleus [14] as well as parent-of-origin specific modifications of pronuclear histone code [9]. However, up-stream factors of histone code in zygote and their influence on embryo development and blastocyst quality are poorly comprehended. Sirtuins (SIRTs) are a family of NADP+-dependent histone-deacetylases including 7 isoforms with specific subcellular localization patterns [15]. Among them, SIRT1 is the most potent regulator of histone code, present notably in the nucleus and it enhances cell viability by regulating epigenome remodeling [16, 17]. The expression of SIRTs in mammalian oocytes and embryos have been observed [18C22], and the essential role of SIRT1 in oocyte maturation and early embryonic development has been established [19, 23]. Accordingly, beneficial effect of red grape flavonoid resveratrol, a cell protectant/antioxidant material and a strong activator of SIRT1, on oocyte quality and success of embryonic development is usually well-known [24C27]; however, we lack the understanding of mechanisms by which SIRT1 enhances oocyte maturation, fertilization and early embryonic development. Based on somatic cell studies, SIRT1 is able to remove the acetyl group from lysine residues of several histones, resulting in deacetylation of histone H1 on lysine Mirk-IN-1 K26 [28, 29], H3 on K9, K14 and K56 [28, 30], FKBP4 and H4 on K8, K12 and K16 [28, 31]. Acetylation of H3K9 is an established marker of translational activity, but it is also frequently associated with DNA damage [32]. Deacetylation of H3K9 makes it available for methyl group addition by histone methyltransferases [33C36]. The involvement of UPS, through the participation of Mouse double minute 2 homolog (MDM2), an E3-type ubiquitin ligase, in SIRT1-mediated H3K9 methylation is usually indicated [37] and remains the lone consideration of SIRT1 mechanism in the nucleus. Based on the above knowledge, we hypothesized that SIRT1 affects acetylation-methylation pattern of H3K9 in formatting porcine zygote pronuclei. We also predicted that this SIRT1-modulated H3K9 zygotic histone code establishment will enhance early embryonic development measured by development to blastocyst and blastocyst quality. Methods Collection and in vitro maturation (IVM) of porcine oocytes Porcine ovaries were obtained from 6- to 8-month-old non-cycling gilts (a crossbreed of Landrace x Large White) at the local slaughterhouse (Jatky Plzen a.s., Plzen,.