SNAI1在人胚胎干细胞定向分化为定型内胚层过程中的作用研究

As a member of the SNAIL family, the most significant role of the zinc finger transcription factor SNAI1 is as an inhibitor of E-cadherin and regulation of epithelial－mesenchymal transition, thus affecting embryonic development and tumor development. But the role of SNAI1 in human embryonic development and embryonic stem cell fate decision is still not clear. A new in vitro endoderm differentiation (DE) system was established to investigate the stem cell fate decision according to the experiments we done before. Through rnaseq data, we found that the expression level of snai1 was significantly increased during the differentiation from hESCs to DE. On the other side, the expression level of snai1 was significantly inhibited by siRNA or Snai1 gene knockout. The results indicated that Snai1 has an important role during the differentiation from hESCs to DE. Therefore, in order to find out the regulatory network and the mechanism of snai1 during stem cell fate decision, gene knockout technology, chromatin immuno co-precipitation and sequencing Chip-Seq should be used in our study to understand the role of snai1.

锌指转录因子SNAI1是SNAIL家族成员之一，其最显著作用是作为E-cadherin的抑制因子，调控细胞的上皮间质转化，从而影响胚胎发育和肿瘤的发生。但是SNAI1在人的胚胎发育和胚胎干细胞命运转变过程中的作用仍然不清楚。我们通过前期实验建立了体外人胚胎干细胞（hESCs）向定型内胚层（DE）分化的体系来研究干细胞细胞命运转变过程中的关键因子，通过RNAseq发现hESCs分化为DE的过程中，SNAI1的表达有显著提高，通过siRNA技术降低SNAI1的表达或者敲除SNAI1基因，发现hESCs分化为DE的过程被显著抑制，说明SNAI1在hESCs分化为DE的过程中有重要的作用。因此，我们试图利用基因敲除技术、染色质免疫共沉淀及测序（Chip-Seq）等技术研究SNAI1的调控网络，阐明SNAI1是如何被激活并且调控哪些基因来调控hESCs分化为DE的机制

人多能干细胞向内、外胚层（尤其是神经外胚层）的分化，一直是研究的热点。有许多基因被认为是人内胚层或者神经外胚层分化的标记基因，但真正决定多能干细胞不可逆转化的关键基因却还未被证实。锌指转录因子SNAI1是SNAIL家族成员之一，其最显著作用是作为E-cadherin的抑制因子，调控细胞的上皮间质转化，从而影响胚胎发育和肿瘤的发生。但是SNAI1在人的胚胎发育和胚胎干细胞命运转变过程中的作用仍然不清楚。本研究通过体外人胚胎干细胞（hESCs）向定型内胚层（DE）分化的体系以及单细胞定量PCR的技术研究发现，整个肝分化过程发生了上皮-间质转化以及间质-上皮转化（EMT-MET）的现象，并且，通过基因敲除技术敲除SNAI1的胚胎干细胞不能分化为定型内胚层以及肝细胞。本研究还采用单细胞定量PCR的技术研究了TGFb通路抑制剂Repsox对内胚层以及外胚层分化的影响，结果表明，Repsox可以抑制内胚层的分化并促进细胞向外胚层命运方向转变。本研究将有助于人们进一步理解早期胚胎发育的机理，并为多能干细胞定向分化的机制研究提供重要思路。