GTF2H5在小鼠胚胎早期发育中的功能和作用机制研究

In vitro fertilization（IVF）can fulfill the entire early embryo events under culture condition, which is the major basis of assisited reproductive technology (ART). Mammalian preimplantation embryo development is a life processes including co-regulation of multi-gene selectively time-space expression, such as conversion of maternal regulation to the zygote regulation. However, embryo events are the outputs of the interplay among hundards of genes, some major genes play dominant function in specific embryo-stage and stay in the central network of genes. It is very important to make clear the biological function and the underlied mechanism of these central factors for clinical uses. Single-cell transcriptome sequencing and weighted gene correlation network analysis (WGCNA) points out GTF2H5 is one of the central factors, it conservedly participate in regulation of gene expression, especially the mitochondrial-related genes in mouse 8-cell embryos. In both human and mouse, GTF2H5 plays very important roles during the initiation of independent energitic supply in early embryo. This project will continue to study the biological role of GTF2H5 in the process from fertilized egg to blastocyte and analysize its mechanism in gene activities and mitochondrial function, we try to extend the theory basis of IVF and find an effective pathway to improve the embryo quality and healthy.

通过体外受精可以在培养条件下完整呈现早期胚胎发育的全部事件，这也是临床辅助生殖的基础。早期胚胎发育是多基因选择性时-空表达共同调控的复杂过程，最终导致母源性调控向合子性调控转变。研究这一过程中关键调控因子的功能和机制，可以更好地指导并改进人工辅助生殖技术。利用单细胞转录组测序及权重基因共表达关联性分析，研究早期胚胎发育过程的基因表达调控规律，我们已经发现了人和小鼠胚胎中均存在一个作用保守的关键调控因子GTF2H5，生物信息学分析表明它在8细胞期胚胎与线粒体相关基因的转录密切相关。本项目进一步深入研究GTF2H5在胚胎从受精卵向囊胚发育进程中的生物学功能以及对线粒体功能调控的作用，并分析其在基因表达调控中的作用机理。本项目的研究成果可以拓展辅助生殖技术的理论依据，找到一条能够提高IVF胚胎正常发育的有效途径。

哺乳动物植入前胚胎发育是跨越物种间高度保守的遗传发育程序，然而也观察到基因网络激活的时间差异和基因表达模块中的基因差异。该研究中，我们重点利用人、食蟹猴和小鼠植入前胚胎模型探讨物种间滋养外胚层（trophoectoderm, TE）和内细胞团（inner cell mass, ICM）关键基因网络的激活。通过单细胞RNA测序分析食蟹猴早期胚胎，我们发现主要胚胎基因组激活发生在早期桑椹胚阶段，出现相对较晚。基因网络保守性分析表明，和小鼠相比，食蟹猴胚胎的遗传程序更接近人类胚胎，更支持灵长类动物的植入前胚胎发育不同于啮齿动物。例如，灵长类动物囊胚ICM和TE差异表达基因为N-MYC和HAND1等，而小鼠囊胚ICM和TE差异表达基因为KLF2和STAT3。有趣的是，三个物种中TE基因网络的整体保守性高于ICM，显示TE发育程序更为保守。此外，TE特异性基因网络完全激活是在囊胚期，在桑椹胚或更早期胚胎则表达较低或无表达。相比之下，大多数ICM特异性基因在第一波主要的EGA时就激活了，在晚期桑椹胚和囊胚阶段进一步的规则性调整。综上所述，我们的研究为哺乳动物植入前胚胎发育以及TE和ICM谱系特异性基因遗传程序的顺序激活提供了新的见解。