Cfp1与Erk信号通路的互反馈调节机制及其对ESC多能性状态的调控

The pluripotent state of mouse embryonic stem cells (ESC) is determined by synergistic actions of exogenous signals, transcription factors and epigenetic modification. Among them, Nanog and Erk signaling pathway play the most important roles. However, the signal transduction and integrating mechanisms of different regulatory pathways remain largely unknown. Cfp1, an epigenetic factor, contributes to both genome-wide DNA methylation and histone methylation. Our previous works have provided the evidence of Cfp1-Erk mutual feedback signaling loop in ESCs, and established Cfp1 as a critical regulator of Nanog gene DNA methylation, Based on these new findings, we plan to reveal the mechanism underlying the mutual feedback loop between Cfp1 and Erk signaling pathway. Furthermore, our project aim to explore how Cfp1-Erk signal feedback loop regulates the epigenetic and pluripotent state of ESCs through epigenetic genomics analysis, transcriptomics analysis, heterogeneity analysis and functional evaluation. These studies would expand our knowledge and understanding of ESC plasticity, which will enable us to control stem cell fate. Moreover, as Cfp1-Erk signaling loop is ubiquitous, our research will also shed light on many other areas of cellular biology.

胚胎干细胞（ESC）的多能性状态受到信号通路、转录因子与表观遗传修饰的协同调控，其中，Nanog和Erk通路是两个最关键的决定因素，但不同调节途径之间的信号转导及整合机制并不清楚。Cfp1是重要的表观遗传因子，兼具DNA甲基化和组蛋白甲基化调控功能。我们前期曾观察到Cfp1-Erk互反馈信号调节回路存在的证据，并且证明Nanog基因的甲基化修饰依赖Cfp1介导。立足于这些原创性发现，本课题拟利用表观基因组学、功能基因组学、ESC异质性及功能评价等技术手段，阐明Cfp1与Erk信号通路的互反馈调控机制，并进一步探索该信号回路调节ESC表观遗传与多能性状态的分子机制。由于Cfp1-Erk信号回路具有泛宿主性，本项目不仅是了解ESC可塑性并实现人工操控的基础，其研究价值还必将在细胞生物学的其它领域得到体现。

胚胎干细胞（ESC）的多能性状态受到信号通路、转录因子与表观遗传修饰的协同调控，但不同调节途径之间的信号转导及整合机制并不清楚。Cfp1是重要的表观遗传因子，兼具DNA甲基化和组蛋白甲基化调控功能。本课题旨在阐明Cfp1与Erk信号通路的互反馈调控机制，并进一步探索该信号回路调节ESC表观遗传与多能性状态的分子机制。我们的研究发现：Cfp1是ESCs退出多能性基态的必要条件，Cfp1缺失的ESCs不能启动分化程序；其机制主要涉及以下两个方面：a. Cfp1 KO抑制Erk1/2活化，从而导致分化的ESCs凋亡；b. Cfp1缺失导致Nanog基因低甲基化，在分化后不能被有效沉默，从而阻止ESCs分化。此外，本课题还取得以下两个研究进展：1. Nac1通过直接调控（促进）c-Myc基因转录，增强ESCs自我更新效率，延迟分化发生；但并非ESCs多能性维持的必要条件（上述研究已作为论著在Oncotarget杂志发表）；2. Bcl2是重要的抗凋亡分子。我们发现在ESCs中存在2个Bcl2的可变剪切体。在无血清培养条件下，两者均能促进ESCs存活及生长，但只有Bcl2α过表达有利于维持ESCs长期扩增及多能性（上述研究已作为论著在Biochemical and Biophysical Research Communications杂志发表）。本项目为了解ESC可塑性并实现人工操控奠定了基础，其研究价值还将在细胞生物学的其它领域得到体现。