申请人主要研究细胞命运转换中的调控机制：1）阐明了Oct4 以及Klf4/Sox2 在调控Slug等下游因子表达时的相互拮抗对体细胞重编程的阻碍作用；2）发现了短时间的TGFβ处理和Slug高表达可以在重编程前期诱导短暂的上皮间充质转化（EMT），进而形成顺序性EMT-MET并提高重编程效率，证明细胞在不同状态间的转化对其命运转换具有重要调控作用；3）揭示了配体选择性信号转导通过ERK、YY1以及NeuroD1调控成体神经发生这一细胞命运转换过程的完整通路。申请人发表论文17篇，总引用371次。作为共同通讯作者在Nat Cell Biol上发表1篇，作为唯一通讯作者和第一作者在PNAS上发表1篇。本项目计划确定顺序性EMT-MET通过表观遗传调控因子（如前期研究中发现的Factor A）促进多种细胞命运转换过程（包括重编程等）的具体机制，以期全面揭示细胞状态与细胞命运之间的相互关系。

The applicant focuses his studies on the mechanisms underlying cell fate conversions. 1) The applicant has found that the counteractions between Oct4 and Klf4/Sox2 in modulating the expression of E-cadherin are important barriers for somatic cell reprogramming; 2) The applicant has also demonstrated that both short-time treatment with TGFβ and over-expression of Slug introduced a temporary and short epithelial-mesenchymal transition (EMT) before the mesenchymal-epithelial transition in the early phase of reprogramming. Such sequential EMT-MET increased the efficiency of fibroblasts reprogramming, which further confirms the critical roles played the transitions between mesenchymal and epithelial states during different processes of cell fate conversions; 3) The applicant has also identified a whole signaling pathway from agonist-biased signaling transduction to ERK1/2, YY1, miR-190, and NeuroD1 during adult neurogenesis in hippocampus, an important cell fate conversion process for adult brain to generate new neurons. The applicant has published 17 manuscripts which has been cited for 371 times totally. The applicant has published one article as co-corresponding author in Nat Cell Biol and one article as the only corresponding author and first author in PNAS. Since the applicant and his group has indentified that an epigenetic-regulating factor, Factor A, can mediate the beneficial roles played by sequential EMT-MET during reprogramming, the current project will continue to further confirm and explore this mechanism, and try to determine whether this mechanism is also applicable in cell fate conversion processes other than somatic cell reprogramming. This project will eventually facilitate our understanding on the relationship between cell states and cell fates.

基于团队在前期研究中发现顺序性EMT-MET对体细胞重编程的重要调控作用，项目计划在确定顺序性EMT-MET对表观遗传修饰的直接调控或者间接调控的基础上，发现包括成纤维细胞重编程在内的多种细胞命运转换过程的新机制。以期全面揭示细胞状态转化或者顺序性EMT-MET与细胞命运转换之间的相互关系。为了在重编程之外的其他细胞命运转换过程中研究顺序性EMT-MET，在本项目的研究过程中，团队首先建立了的利用少量细胞生长因子和小分子化合物诱导小鼠胚胎成纤维细胞转分化为神经细胞的技术平台。这一技术平台同样适用于体外培养的大鼠神经胶质细胞以及在体内环境中小鼠神经胶质细胞。在进一步研究这一神经细胞转分化分的过程中，研究团队发现转分化中也存在顺序性EMT-MET，同时无论是抑制早期的EMT还是晚期的MET都会显著降低转分化效率，提示顺序性EMT-MET在神经细胞转分化中也发挥着重要作用。进一步的研究发现这样的顺序性EMT-MET是由于转分化早起Stat3-Sox2通路被激活导致的。结合顺序性EMT-MET在体细胞重编程以及干细胞分化中的重要作用，团队提出顺序性EMT-MET是细胞命运转换的重要机理之一。此后，研究的团队以顺序性EMT-MET为切入点，发现：sh-Lsd1通过调控组蛋白甲基化（H3K4 methylation）影响细胞代谢进而促进体细胞重编程；sh-Dnmt1通过调控DNA甲基化促进多能性因子的表达进而促进体细胞重编程。项目合计发表标注（第一位或者第二位标注）的科研论文6篇，申请国家发明专利3项，培养硕士研究生3名。项目到位经费100万元，实际支出98.5万元。相关经费使用均遵守国家、基金委以及中科院的相关规定。