The Role of Hypoxia in Transcriptomics and Epigenomics Regulation during Pre-Implantation Embryo Development

Hypoxia as the major stressor in embryo, placental, and fetal development, has been suggested to affect epigenetic regulation. Epigenetic regulation is very important in early embryo development for it can affect genomic imprinting, gene reprogramming and gene expression. Although most of the evidences indicated that pre-implantation embryo is surrounding with relative low oxygen environment and hypoxia might do some benefit for stem cell culture, the effects and impacts of hypoxia to embryo development is still unclear. To study the responses to hypoxia stress and gene regulation during pre-implantation embryo development, this project is trying to examine the effects of hypoxia in pre-implantation embryo development and hatching, also the mRNA and microRNA gene expression and epigenetic regulation in the mouse embryo in response to anoxia (0%) and hypoxia (1, 5, 10% of oxygen) as comparing to normoxia condition will be clarified and correlated with the hypoxic affects. According to our previous findings, by integrating the technologies of T7-based RNA amplification and cDNA microarray, several embryo development and hatching-related genes were identified, including epigenetic regulators (DNA methylation and histone acetylation, including Dnmt1, Dnmt2, Dnmt3a, Dnmt3b, HD-1, SIN3a, and SIN3b) and hypoxia-inducing factors (e.g., HO-1 and HIF-1), these factors have been found to play an important role in epigenetic regulation and as survival factors during embryo development and implantation process. Here, there are at least four major and specific aims will be proceeding in three years in this project: (1) For the first year, the effects of hypoxia on embryo development and related gene expression (transcriptomics and microRNA) profiles will be examined by Affymetrix DNA Chip and Q-PCR-based megaplex pre-amp microRNA assay. (2) The 2nd year, the epigenetic regulators (DNA methylation and histone acetylation) and related mechanisms will be studied in mouse embryo in responses to hypoxia condition. (3) In the 3rd year, the roles of hypoxia-regulated factors (e.g., HO-1 and HIF-1) in embryo, placental, and fetal development will be studied in vivo. (4) Also, we will trying to integrate the results and information of hypoxia-induced gene expression profiles, epigenetic regulation, and the embryo development signaling to identify the mechanisms of the influences of hypoxia in embryo development by the genome-wide iterative enrichment analysis in composite regulatory signature database (CRSD). This project should be important for clarify the roles of hypoxia condition in embryo development and might provide information for improving the embryo culture in vitro environment for controlling the fertility and helpful for reproductive medicine.