Small RNA pathways in the regulation of bovine oocyte maturation and early embryogenesis

建议书摘要 加拿大养牛业每年为经济贡献数十亿美元和数千个就业机会。动物的生产力取决于繁殖力，而早孕失败是限制这一领域生产力的主要因素。与其他哺乳动物一样，牛的早期胚胎发育是成功怀孕的关键。从科学的角度来看，对控制胚胎生长和发育的机制的探索为一些最基本的生物学问题提供了迷人的见解，因为它们适用于许多不同的物种。胚胎的生长、发育和存活取决于多种因素，其中最重要的是严格、适时地打开和关闭动物DNA中的特定基因。这个过程控制着“基因表达”的水平，大致可以定义为在特定时间存在于动物细胞中的特定RNA或蛋白质分子的实际水平。基因表达控制异常的胚胎发育异常或根本无法发育。基因表达的控制是非常复杂的，涉及不同的途径，增加或减少细胞、组织或生物体中编码特定蛋白质的RNA的总水平。这些因素包括改变产生(转录)的信使RNA(MRNA)数量的因素，以及改变这些相同的mRNAs被破坏或被用作蛋白质生产模板的速度的因素。动物体内通过抑制蛋白质生产或加速RNA的衰变来改变基因表达的途径称为“转录后”机制或途径。这项研究计划将研究控制重要基因表达的非常年轻的奶牛胚胎的转录后途径，并评估这些过程如何影响它们的发育和生存。利用尖端的分子生物学技术，以及通过体外受精产生的牛胚胎，我们的研究将检查非常强大的、特定的称为microRNAs的小RNA分子的作用，它通过这些途径调节卵母细胞和胚胎中的基因表达。这些微小RNA的水平或活动的差异很可能影响怀孕和发育，并将进行详细的识别和检查。这些研究应该有助于揭示控制奶牛雌性受精和早期胚胎发育的重要新途径。最终，我们希望这些知识将直接有助于提高牛的繁殖力的策略。

Summary of Proposal The Canadian cattle industry contributes billions of dollars and thousands of jobs annually to the economy. Animal productivity depends on fertility and early pregnancy failure is a major factor limiting productivity in this area. In cattle, as in other mammals, early embryonic development represents a critical point in the establishment of successful pregnancies. From a scientific standpoint, the exploration of mechanisms that control embryonic growth and development provide fascinating insights into some of the most fundamental biological questions as they apply to many different species. Growth, development and viability of the embryo depends on multiple factors, the most important of which is the strict, well-timed turning "on" and "off" of specific genes in the animal's DNA. This process controls the level of "gene expression" which can be loosely defined as the actual level of specific RNA or protein molecules that are present in an animal's cell at a particular time. Embryos that have abnormal control of gene expression develop abnormally or fail to develop at all. Control of gene expression is very complicated and involves different pathways that increase or decrease the overall levels of the RNAs that encode specific proteins in cells, tissues or organisms. These include factors that change the amount of messenger RNA (mRNA) that is produced (transcription) and factors that change the rate at which those same mRNAs are destroyed or are used as templates for the production of protein. The pathways in animals that use the inhibition of protein production or cause accelerated decay of RNA in order to change gene expression are called "post-transcriptional" mechanisms or pathways. This research program will investigate post-transcriptional pathways in very young cow embryos that control the expression of important genes, and evaluate how these processes impact their development and survival. Using cutting-edge molecular biology techniques, and bovine embryos generated by in vitro fertilization, our studies will examine the roles of very potent, specific small RNA molecules called microRNAs that regulate the expression of genes in oocytes and embryos through these pathways. Differences in the levels or activities of these microRNAs are very likely to influence pregnancy and development and will be identified and examined in detail. These studies should help reveal important new pathways that control female fertility and early embryo development in the cow. Ultimately, we hope that this knowledge will contribute directly to strategies that improve fertility in cattle.