Dynamic changes in maternal‒zygotic transition (MZT) require complex regulation of zygote formation, maternal transcript decay, embryonic genome activation (EGA), and cell cycle progression. Although these changes are well described, some key regulatory factors are still elusive. Sirtuin-1 (SIRT1), an NAD+-dependent histone deacetylase, is a versatile driver of MZT via its epigenetic and nonepigenetic substrates. This study focused on the dynamics of SIRT1 in early embryos and its contribution to MZT. A conditional SIRT1-deficient knockout mouse model was used, accompanied by porcine and human embryos. Embryos across mammalian species showed the prominent localization of SIRT1 in the nucleus throughout early embryonic development. Accordingly, SIRT1 interacts with histone H4 on lysine K16 (H4K16) in both mouse and human blastocysts. While maternal SIRT1 is dispensable for MZT, at least one allele of embryonic Sirt1 is required for early embryonic development around the time of EGA. This role of SIRT1 is surprisingly mediated via a transcription-independent mode of action.

• MeSH
• blastocysta metabolismus   MeSH
• embryo savčí metabolismus   MeSH
• embryonální vývoj * genetika   MeSH
• histony metabolismus   MeSH
• lidé MeSH
• myši knockoutované * MeSH
• myši MeSH
• prasata MeSH
• sirtuin 1 * metabolismus   genetika   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• zygota * metabolismus   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

RNA silencing is a complex of mechanisms that regulate gene expression through small RNA molecules. The microRNA (miRNA) pathway is the most common of these in mammals. Genome-encoded miRNAs suppress translation in a sequence-specific manner and facilitate shifts in gene expression during developmental transitions. Here, we discuss the role of miRNAs in oocyte-to-zygote transition and in the control of pluripotency. Existing data suggest a common principle involving miRNAs in defining pluripotent and differentiated cells. RNA silencing pathways also rapidly evolve, resulting in many unique features of RNA silencing in different taxonomic groups. This is exemplified in the mouse model of oocyte-to-zygote transition, in which the endogenous RNA interference pathway has acquired a novel role in regulating protein-coding genes, while the miRNA pathway has become transiently suppressed.

• MeSH
• fylogeneze MeSH
• lidé MeSH
• malá interferující RNA genetika   metabolismus   MeSH
• mikro RNA klasifikace   genetika   metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• oocyty cytologie   fyziologie   MeSH
• pluripotentní kmenové buňky cytologie   fyziologie   MeSH
• RNA interference MeSH
• sekvence nukleotidů MeSH
• sekvenční seřazení MeSH
• zvířata MeSH
• zygota cytologie   fyziologie   MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The oocyte (maternal) nucleolus is essential for early embryonic development and embryos originating from enucleolated oocytes arrest at the 2-cell stage. The reason for this is unclear. Surprisingly, RNA polymerase I activity in nucleolus-less mouse embryos, as manifested by pre-rRNA synthesis, and pre-rRNA processing are not affected, indicating an unusual role of the nucleolus. We report here that the maternal nucleolus is indispensable for the regulation of major and minor satellite repeats soon after fertilisation. During the first embryonic cell cycle, absence of the nucleolus causes a significant reduction in major and minor satellite DNA by 12% and 18%, respectively. The expression of satellite transcripts is also affected, being reduced by more than half. Moreover, extensive chromosome bridging of the major and minor satellite sequences was observed during the first mitosis. Finally, we show that the absence of the maternal nucleolus alters S-phase dynamics and causes abnormal deposition of the H3.3 histone chaperone DAXX in pronuclei of nucleolus-less zygotes.

• MeSH
• blastocysta cytologie   metabolismus   MeSH
• buněčné jadérko metabolismus   MeSH
• centromera metabolismus   MeSH
• embryo savčí cytologie   metabolismus   MeSH
• genetická transkripce MeSH
• genom genetika   MeSH
• heterochromatin genetika   MeSH
• messenger RNA genetika   metabolismus   MeSH
• mikrosatelitní repetice genetika   MeSH
• minisatelitní repetice genetika   MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• posttranskripční úpravy RNA genetika   MeSH
• prekurzory RNA genetika   MeSH
• rekombinace genetická genetika   MeSH
• replikace DNA genetika   MeSH
• restrukturace chromatinu genetika   MeSH
• RNA ribozomální biosyntéza   genetika   MeSH
• S fáze genetika   MeSH
• savčí chromozomy metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The oocyte-to-embryo transition (OET) denotes transformation of a highly differentiated oocyte into totipotent blastomeres of the early mammalian embryo. OET depends exclusively on maternal RNAs and proteins accumulated during oocyte growth, which implies importance of post-transcriptional control of gene expression. OET includes replacement of abundant maternal microRNAs (miRNAs), enriched also in differentiated cells and exemplified by the Let-7 family, with embryonic miRNAs common in pluripotent stem cells (the miR-290 family in the mouse). Lin28a and its homolog Lin28b encode RNA-binding proteins, which interfere with Let-7 maturation and facilitate reprogramming of induced pluripotent stem cells. Both Lin28a and Lin28b transcripts are abundant in mouse oocytes. To test the role of maternal expression of Lin28a and Lin28b during oocyte-to-zygote reprogramming, we generated mice with oocyte-specific knockdown of both genes by using transgenic RNA interference. Lin28a and Lin28b are dispensable during oocyte growth because their knockdown has no effect on Let-7a levels in fully grown germinal vesicle (GV)-intact oocytes. Furthermore, transgenic females were fertile and produced healthy offspring, and their overall breeding performance was comparable to that of wild-type mice. At the same time, 2-cell embryos derived from transgenic females showed up-regulation of mature Let-7, suggesting that maternally provided LIN28A and LIN28B function during zygotic genome activation. Consistent with this conclusion is increased translation of Lin28a transcripts upon resumption of meiosis. Our data imply dual repression of Let-7 during OET in the mouse model, the selective suppression of Let-7 biogenesis by Lin28 homologs superimposed on previously reported global suppression of miRNA activity.

• MeSH
• blastocysta cytologie   MeSH
• blastomery cytologie   MeSH
• buněčná diferenciace MeSH
• DNA vazebné proteiny genetika   fyziologie   MeSH
• kultivace embrya MeSH
• luciferasy genetika   MeSH
• mikro RNA genetika   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• oocyty cytologie   MeSH
• přenos embrya metody   MeSH
• proteiny vázající RNA genetika   fyziologie   MeSH
• RNA interference fyziologie   MeSH
• RNA messenger skladovaná genetika   MeSH
• těhotenství MeSH
• totipotentní kmenové buňky cytologie   MeSH
• zvířata MeSH
• zygota cytologie   MeSH
• Check Tag
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Oocyte-to-embryo transition is a process during which an oocyte ovulates, is fertilized, and becomes a developing embryo. It involves the first major genome reprogramming event in life of an organism where gene expression, which gave rise to a differentiated oocyte, is remodeled in order to establish totipotency in blastomeres of an early embryo. This remodeling involves replacement of maternal RNAs with zygotic RNAs through maternal RNA degradation and zygotic genome activation. This review is focused on expression and function of long noncoding RNAs (lncRNAs) and small RNAs during oocyte-to-embryo transition in mammals. LncRNAs are an assorted rapidly evolving collection of RNAs, which have no apparent protein-coding capacity. Their biogenesis is similar to mRNAs including transcriptional control and post-transcriptional processing. Diverse molecular and biological roles were assigned to lncRNAs although most of them probably did not acquire a detectable biological role. Since some lncRNAs serve as precursors for small noncoding regulatory RNAs in RNA silencing pathways, both types of noncoding RNA are reviewed together.

• MeSH
• blastomery chemie   MeSH
• gastrulace MeSH
• lidé MeSH
• malá nekódující RNA genetika   MeSH
• RNA dlouhá nekódující genetika   MeSH
• savci embryologie   genetika   MeSH
• stabilita RNA MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The oocyte-to-embryo transition (OET) transforms a differentiated gamete into pluripotent blastomeres. The accompanying maternal-zygotic RNA exchange involves remodeling of the long non-coding RNA (lncRNA) pool. Here, we used next generation sequencing and de novo transcript assembly to define the core population of 1,600 lncRNAs expressed during the OET (lncRNAs). Relative to mRNAs, OET lncRNAs were less expressed and had shorter transcripts, mainly due to fewer exons and shorter 5' terminal exons. Approximately half of OET lncRNA promoters originated in retrotransposons suggesting their recent emergence. Except for a small group of ubiquitous lncRNAs, maternal and zygotic lncRNAs formed two distinct populations. The bulk of maternal lncRNAs was degraded before the zygotic genome activation. Interestingly, maternal lncRNAs seemed to undergo cytoplasmic polyadenylation observed for dormant mRNAs. We also identified lncRNAs giving rise to trans-acting short interfering RNAs, which represent a novel lncRNA category. Altogether, we defined the core OET lncRNA transcriptome and characterized its remodeling during early development. Our results are consistent with the notion that rapidly evolving lncRNAs constitute signatures of cells-of-origin while a minority plays an active role in control of gene expression across OET. Our data presented here provide an excellent source for further OET lncRNA studies.

• MeSH
• blastomery metabolismus   MeSH
• embryo savčí metabolismus   MeSH
• myši MeSH
• oocyty metabolismus   MeSH
• RNA dlouhá nekódující genetika   metabolismus   MeSH
• sekvenční analýza RNA MeSH
• stanovení celkové genové exprese MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• vývojová regulace genové exprese * MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The oocyte-to-embryo transition (OET) arguably initiates with formation of a primordial follicle and culminates with reprogramming of gene expression during the course of zygotic genome activation. This transition results in converting a highly differentiated cell, i.e. oocyte, to undifferentiated cells, i.e. initial blastomeres of a preimplantation embryo. A plethora of changes occur during the OET and include, but are not limited to, changes in transcription, chromatin structure, and protein synthesis; accumulation of macromolecules and organelles that will comprise the oocyte's maternal contribution to the early embryo; sequential acquisition of meiotic and developmental competence to name but a few. This review will focus on transcriptional and post-transcriptional changes that occur during OET in mouse because such changes are likely the major driving force for OET. We often take a historical and personal perspective, and highlight how advances in experimental methods often catalyzed conceptual advances in understanding the molecular bases for OET. We also point out questions that remain open and therefore represent topics of interest for future investigation.

• MeSH
• buněčná diferenciace fyziologie   MeSH
• embryonální vývoj fyziologie   MeSH
• genom MeSH
• myši MeSH
• oocyty fyziologie   MeSH
• ovariální folikul fyziologie   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, N.I.H., Intramural MeSH

In mouse, the oocyte-to-embryo transition entails converting a highly differentiated oocyte to totipotent blastomeres. This transition is driven by degradation of maternal mRNAs, which results in loss of oocyte identity, and reprogramming of gene expression during the course of zygotic gene activation, which occurs primarily during the two-cell stage and confers blastomere totipotency. Full-grown oocytes are transcriptionally quiescent and mRNAs are remarkably stable in oocytes due to the RNA-binding protein MSY2, which stabilizes mRNAs, and low activity of the 5' and 3' RNA degradation machinery. Oocyte maturation initiates a transition from mRNA stability to instability due to phosphorylation of MSY2, which makes mRNAs more susceptible to the RNA degradation machinery, and recruitment of dormant maternal mRNAs that encode for critical components of the 5' and 3' RNA degradation machinery. Small RNAs (miRNA, siRNA, and piRNA) play little, if any, role in mRNA degradation that occurs during maturation. Many mRNAs are totally degraded but a substantial fraction is only partially degraded, their degradation completed by the end of the two-cell stage. Genome activation initiates during the one-cell stage, is promiscuous, low level, and genome wide (and includes both inter- and intragenic regions) and produces transcripts that are inefficiently spliced and polyadenylated. The major wave of genome activation in two-cell embryos involves expression of thousands of new genes. This unique pattern of gene expression is the product of maternal mRNAs recruited during maturation that encode for transcription factors and chromatin remodelers, as well as dramatic changes in chromatin structure due to incorporation of histone variants and modified histones.

• MeSH
• embryo savčí metabolismus   MeSH
• genom MeSH
• myši MeSH
• oocyty metabolismus   MeSH
• stabilita RNA genetika   MeSH
• transkriptom genetika   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH

Removal of poly(A) tail is an important mechanism controlling eukaryotic mRNA turnover. The major eukaryotic deadenylase complex CCR4-NOT contains two deadenylase components, CCR4 and CAF1, for which mammalian CCR4 is encoded by Cnot6 or Cnot6l paralogs. We show that Cnot6l apparently supplies the majority of CCR4 in the maternal CCR4-NOT in mouse, hamster, and bovine oocytes. Deletion of Cnot6l yielded viable mice, but Cnot6l-/- females exhibited ∼40% smaller litter size. The main onset of the phenotype was post-zygotic: fertilized Cnot6l-/- eggs developed slower and arrested more frequently than Cnot6l+/- eggs, suggesting that maternal CNOT6L is necessary for accurate oocyte-to-embryo transition. Transcriptome analysis revealed major transcriptome changes in Cnot6l-/- ovulated eggs and one-cell zygotes. In contrast, minimal transcriptome changes in preovulatory Cnot6l-/- oocytes were consistent with reported Cnot6l mRNA dormancy. A minimal overlap between transcripts sensitive to decapping inhibition and Cnot6l loss suggests that decapping and CNOT6L-mediated deadenylation selectively target distinct subsets of mRNAs during oocyte-to-embryo transition in mouse.

• Publikační typ
• časopisecké články MeSH

The beginning of development is controlled parentally. For example, early zygotic proteosynthesis produces proteins encoded by the maternal transcriptome. As parental factors become replaced by factors synthesized in the embryo, parental developmental control is gradually passed to the embryo. This chapter focuses on the clearance of parental factors during oocyte-to-embryo transition in vertebrates. Coordinated removal of parental factors erases ancestral oocyte identity of the zygote and facilitates reprogramming of gene expression into a state that will support development of a new organism. Here, we will review functional and mechanistic aspects of clearance of selected parental factors from early embryos, including different types of maternal RNAs, proteins, erasure of chromatin features of maternal and paternal genomes, as well as consumption of yolk and elimination of paternal mitochondria.

• MeSH
• chromatin MeSH
• embryo savčí * MeSH
• oocyty * MeSH
• transkriptom MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• zygota * MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH