Gene Expression in the Preimplantation Mouse Embryo

描述（由申请人提供）：本申请的长期目标是确定在卵母细胞生长和母体向受精卵转变过程中控制基因表达变化的潜在机制，这两者都是相互关联的，对发育至关重要。卵母细胞发育的一个普遍特征是转录在生长中期开始下降，因此完全发育的卵母细胞基本上处于转录静止状态。在小鼠中，这种下降与染色质结构的明显变化相关，染色质结构变得更加浓缩，转录机制的活性降低。使用转基因RNAi方法，允许研究任何基因在卵母细胞发育中的功能，Specific Aim 1将测试染色质结合蛋白HP1家族成员和UBC9的假设，通过其在sumo化中的核心作用，对卵母细胞生长过程中染色质结构和转录活性的变化至关重要。在2细胞阶段首次检测到基因表达的主要重编程，这对继续发育至关重要。与基因组激活叠加的是染色质介导的转录抑制状态的发展。我们的转录谱分析实验发现，Myc是基因组激活和基因表达重编程的关键候选基因，而Hdad是建立转录抑制状态的必要基因。使用RNAi方法靶向Myc和Hdad， Specific Aim 2将验证Myc和Hdad对这两个过程至关重要的假设，这两个过程协同塑造了基因组激活后成功发育所需的适当基因表达模式。卵母细胞表达miRNAs和mRNA降解，这种降解始于卵母细胞成熟过程，并持续到胚胎着床前的早期发育，是一种转录后机制，有助于确定胚胎中基因表达的全局模式。特异性Aim 3将验证mirna靶向特定mrna降解p小体的假设，以及该机制对卵母细胞/胚胎的正常发育至关重要。拟议的研究将增加我们对人类发展的基本知识和理解。在短期内，它们可能通过提供新知识来帮助改善人类不孕症的治疗，这些知识将有助于在辅助生殖技术（ART）实践中促进改善卵母细胞和植入前胚胎发育的治疗方法的合理发展。

DESCRIPTION (provided by applicant): The long-term goal of this application is to determine underlying mechanisms that govern changes in gene expression during oocyte growth and the maternal-to-zygotic transition, both of which are linked and essential for development. A universal feature of oocyte development is that transcription declines commencing around mid-growth such that fully-grown oocytes are essentially transcriptionally quiescent. In mouse, this decline correlates with visible changes in chromatin structure, which becomes more condensed and decreased activity of the transcription machinery. Using a transgenic RNAi approach that permits study of the function of any gene in oocyte development, Specific Aim 1 will test the hypothesis that members of the HP1 family of chromatin-binding proteins and UBC9, via its central role in sumoylation, are essential for changes in chromatin structure and transcriptional activity that occur during oocyte growth. A major reprogramming of gene expression is first detected during the 2-cell stage and essential for continued development. Superimposed on genome activation is development of a chromatin-mediated transcriptionally repressive state. Our transcript profiling experiments identified Myc as a candidate gene pivotal for genome activation and reprogramming of gene expression, and Hdad as essential for establishing the transcriptionally repressive state. Using an RNAi approach to target Myc and Hdad, Specific Aim 2 will test the hypothesis that Myc and Hdad are critical for these two processes that collaboratively sculpt the appropriate pattern of gene expression required for successful development following genome activation. Oocytes express miRNAs and mRNA degradation, which initiates during oocyte maturation and continues during early preimplantation development, is a post-transcriptional mechanism that contributes to determining the global pattern of gene expression in the embryo. Specific Aim 3 will test the hypothesis that miRNAs target specific mRNAs for degradation in P-bodies and that this mechanism is essential for proper oocyte/embryo development. The proposed studies will increase our basic knowledge and understanding of human development. In the near term, they may help improve treatment of human infertility by providing new knowledge that will facilitate the rational development of treatments that foster improved oocyte and preimplantation embryo development in the practice of Assisted Reproductive Technology (ART).