Regulation of early embryo development by nitric oxide

描述（由申请人提供）：在胚胎发育的围着床阶段，大量潜在妊娠丢失。据国家研究委员会生命科学委员会估计，我国每年有超过20万新生儿在胚胎发育过程中出现异常。其他婴儿的出生体重明显偏低，这可能在出生后的生活中导致死亡或残疾。这些异常的很大一部分可能是由于正常胚胎发育的改变。我们的研究表明，一氧化氮（NO）是胚胎着床前发育所必需的。此外，暴露于雌激素诱导着床，使休眠囊胚的NO产量增加10倍。然而，一氧化氮对围着床期胚胎基因表达的影响尚不清楚。

DESCRIPTION (provided by applicant): A significant number of potential pregnancies are lost during the periimplantation stages of embryo development. It has been estimated by the Commission on Life Sciences of the National Research Council that more than 200,000 infants born each year in this country have abnormalities that arise during embryonic development. Other infants have markedly low birth weights which may result in death or disability later in postnatal life. A large portion of these abnormalities may result from alterations of normal embryonic development. Our studies have indicated that nitric oxide (NO) is required for preimplantation embryo development. In addition, exposure to estrogen, which induced implantation, increases the production of NO 10 fold in dormant blastocysts. However, little is known about the affect of NO on gene expression in periimplantation embryos. The purpose of the proposed experiments is to elucidate the integrated mechanisms regulated by NO in early embryonic development and initiation of implantation. This will be accomplished by conducting the following experiments: (a) Compare the localization of expression of the nitric oxide synthase (NOS) genes in embryos on days 1-4 of pregnancy (preimplantation). Results will indicate if induction of more than one NOS gene is required for NO production and if there is differential expression of these genes during preimplantation embryo; (b) Determine the nature of signaling cascades generated by NO in the embryo on days 1-4 of pregnancy. Specifically we will examine the effect, time course and cell specificity of cell cycle genes including: early immediate genes: c-los, c-jun and e-myc (mRNA and protein), cyclins (D,E, A and B) and retinoblastoma gene in response to NO. Results will determine if NO is acting through the activation of immediate early genes to genes regulating the cell cycle: (c) Determine if the inhibition of NO production alters expression of cell-cycle checkpoint genes. Determine the effect of inhibition of NO on the time course and cell specificity of levels of the cell-cycle checkpoint genes ATM, ATR, MAD and BUB in embryos on days 1-4 of pregnancy. Results will indicate if inhibition of NO stops normal mitotic division by altering expression of checkpoint genes. The proposed study will establish the status of NO production in the embryo and its effects on embryonic gene expression will generate important and meaningful information regarding normal and abnormal reproductive functions. Furthermore, this information should have implications in human fertility treatments, as a tool to select healthier IVF-derived embryos with increased probability for successful pregnancy.