母源SMAD2/3调控牛早期胚胎发育的作用机理研究

Early embryonic loss is a major contributing factor to infertility in dairy cows. A growing body of evidence indicates that oocyte quality is a key factor limiting successful embryonic development following fertilization. Of interest, oocyte-derived maternal factors play a key role in oocyte maturation, embryonic genome activation and other important developmental events during early embryonic development. We previously identified that TGF-β signal component SMAD2/3 mRNA expression profiles resemble the one of typical maternal-effect genes; knockdown or inhibition of SMAD2/3 led to reduced developmental rate to blastocyst stage and reduced expression of CTGF, a putative trophectoderm marker. In the present project, a variety of cutting-edge molecular and embryological techniques will be used to identify the effect of maternal SMAD2/3 on maternal-embryonic transition, the first lineage specification and if CTGF is involved and elucidate the regulatory role of SMAD2/3 in oocyte maturation, fertilization and developmental events of early embryos. The study will provide novel knowledge that may ultimately improve bovine reproduction through better understanding of the functional role of maternal SMAD2/3 in cattle.

早期胚胎死亡是造成奶牛繁殖率低下的主要原因之一。卵子质量则是关乎早期胚胎发育的关键因素。卵子中的母源因子在卵母细胞成熟、胚胎基因组激活等过程发挥着重要作用，但母源因子的调控机制尚不清楚。我们前期的研究发现TGF-β信号通路分子SMAD2/3呈现典型的母源效应基因表达模式，SMAD2/3的缺失造成牛早期胚胎发育率降低，影响滋养层候选标记CTGF的表达，但是其作用机制还不清楚。基于前期工作，本项目拟通过体外受精、显微注射siRNA/mRNA、抑制剂处理等技术研究母源SMAD2/3对牛早期胚胎中母源mRNA清除、胚胎基因组激活的影响，分析母源SMAD2/3在胚胎第一次细胞系分化过程中的作用以及CTGF是否参与介导，并探讨SMAD2/3对牛卵母细胞成熟的作用和机制。本项目的开展将进一步加深对牛早期胚胎发育过程中母源调控机制的理解，有助于研发相关技术减少早期胚胎死亡，进而提高奶牛繁殖率。

早期胚胎死亡是造成奶牛繁殖率低下的主要原因之一。卵子质量则是关乎早期胚胎发育的关键因素。卵子中的母源因子在卵母细胞成熟、胚胎基因组激活等过程发挥着重要作用，但母源因子的调控机制尚不清楚。我们前期的研究发现TGF-β信号通路分子SMAD2/3呈现典型的母源效应基因表达模式，SMAD2/3的缺失造成牛早期胚胎发育率降低，影响滋养层候选标记CTGF的表达，但是其作用机制还不清楚。在本项目的资助下，我们发现SMAD2/3信号通路的抑制显著影响牛早期胚胎发育，揭示SMAD2敲低影响CTGF的表达，建立了牛早期胚胎中的单碱基基因编辑技术体系，挖掘到重要母源因子NOTCH1和H1FOO在牛早期胚胎发育过程中发挥着重要作用。本项目取得了一系列研究成果，在Development、PLOS Genetics、Biology of Reproduction等主流杂志发表论文9篇；培养博士生7名（其中埃及留学生1名），硕士生3名。