Dynamics of Global Gene Expression Changes during Mouse Preimplantation Development

Abstract

Understanding preimplantation development is important both for basic reproductive biology and for practical applications including regenerative medicine and livestock breeding. Global expression profiles revealed and characterized the distinctive patterns of maternal RNA degradation and zygotic gene activation, including two major transient waves of de novo transcription. The first wave corresponds to zygotic genome activation (ZGA); the second wave, named mid-preimplantation gene activation (MGA), precedes the dynamic morphological and functional changes from the morula to blastocyst stage. Further expression profiling of embryos treated with inhibitors of transcription, translation, and DNA replication revealed that the translation of maternal RNAs is required for the initiation of ZGA. We propose a cascade of gene activation from maternal RNA/protein sets to ZGA gene sets and thence to MGA gene sets. The large number of genes identified as involved in each phase is a first step toward analysis of the complex gene regulatory networks.

Expression of all Wnt genes and their secreted antagonists during mouse blastocyst and postimplantation development

“…Recently published PCR surveys including a nested PCR approach detected the expression of numerous Wnts in the mouse blastocysts (Lloyd et al, 2003;Mohamed et al, 2004). Blastocyst expression of Wnt3a, Wnt6, and Wnt7b was also found in microarray studies published recently (Hamatani et al, 2004;Wang et al, 2004). In the present study, it is shown that the highest expression level for the Wnt3a, genes was in the blastocyst.…”

“…Recently, the expression of several Wnt genes was analyzed at preimplantation stages by classic and nested polymerase chain reaction (PCR) as well as by microarrays and mRNAs encoding for Wnt1, were detected (Lloyd et al, 2003;Hamatani et al, 2004;Mohamed et al, 2004;Wang et al, 2004). In addition, it was shown that activation of the Wnt signaling pathway is sufficient to maintain the pluripotency of embryonic stem cells and that betaCatenin was localized in the nuclei of the inner cell mass (ICM) cells but not of the trophoblast cells in the blastocyst (Sato et al, 2004;Wang et al, 2004).…”

Transitioning from egg to embryo: Triggers and mechanisms of egg activation

“…Upon activation nanos mRNA is degraded everywhere except the posterior pole of the oocyte, where it is translated and functions in posterior patterning (Bashirullah et al, 1999;Bergsten and Gavis, 1999). Degradation can also remove mRNAs whose products are no longer needed or that interfere with later development, such as during the maternal to zygotic transition (MZT; mammals, zebrafish) or mid-blastula transition (MBT; Xenopus, Drosophila) (Bashirullah et al, 1999;Hamatani et al, 2004;Giraldez et al, 2006;Tadros et al, 2007).…”

High-throughput screen for genes predominantly expressed in the ICM of mouse blastocysts by whole mount in situ hybridization

“…1C). First, we identified 6484 genes that are highly expressed in mouse blastocysts by examining EST frequency data (Sharov et al, 2003) and microarray data (Hamatani et al, 2004). We then attempted to identify candidate genes that are expressed more highly in the ICM than in TE cells.…”

“…A large number of cDNA clones have been identified from mouse preimplantation embryos and mapped to the mouse genome Sharov et al, 2003;Solter et al, 2002). Microarray analysis of the preimplantation embryos has provided global picture of expression changes during preimplantation mouse development (Hamatani et al, 2004;Tanaka and Ko, 2004;Wang et al, 2004;Zeng et al, 2004). The knowledge of genes expressed in preimplantation mouse embryos has increased dramatically.…”