Global Gene Expression Profile In Mouse 2-Cell Stage Embryo

Preimplantation development encompasses the period from fertilization to implantation, and is marked by number of critical events. In mice, 2-cell stage is a very significant stage in preimplantation development since the gene expression profile is changing dramatically and the development of embryo become from maternal genes driven to zygote genes driven. Fertilization triggers the degradation of oocyte-stored transcripts, which is almost complete by the 2-cell stage. Transcription from the newly formed zygotic genome, known as zygotic genome activation, establishes the gene-expression patterns that are required for continued development.This change of gene expression pattern in embryo developmental process is not just a couple of key genes upregulated or downregulated, but a complex gene net involves in this change.To investigate the gene expression profile in 2-cell stage mice embryo, KM white females were superovulated by injection of 10 IU of PMSG, followed by injection of 10 IU of hCG 48–56 hr later. To collect embryos, females were mated with males after hCG treatment. Collections were made at 40h (early 2-cell) and 49h (late 2-cell). After collecting embryos and RNA be extracted and processed,microarrays containing approximately 25000 known genes were applied to get the data about gene expression change. After analysis, we got the following result.1. There are 5136 genes expressed in 2-cell stage embryo which occupied 20.5% of all genes of mice.2. We got 1248 genes expressed differently between the early 2-cell and late 2-cell stage after analysis which included 847 up-regulated genes and 401 down-regulated genes in late stage compared with the early stage.3. Pathway analysis showed differentially expressed genes were mainly involved in cell cycle related pathways, MAPK signaling pathway, adherens junction pathways and regulation of actin cytoskeleton pathways. And some evolutionarily conserved members of some highly development-related pathway such as WNT, NOTCH, BMP are changed greatly from early stage to late stage of 2-cell embryo.4. The gene ontology category indicated these differentially expressed genes mainly participate in cellular component, cell process, catalytic activity and molecular binding, a part of genes were involved in organelle component, metabolic process, biologic process and signal transducer activity.This work would provide a beneficial reference for understand the mechanism of mammal preimplantation development.