Oct4泛素连接酶在发育多能性的建立和维持中的作用及机制研究

Oct4是调控胚胎干细胞多能性与自我更新的核心转录因子，其表达水平是决定细胞状态和分化方向的重要因素。我们以前的研究证明E3泛素连接酶Wwp2能特异性地催化Oct4的泛素化修饰。最近，我们发现与Wwp2同一家族的Wwp1与Itch也能特异性地催化Oct4的泛素化修饰。前期研究提示Wwp1、Wwp2与Itch可能在不同的细胞状态下调节Oct4的蛋白水平与转录活性，并参与发育多能性的调控。 此外，这三个连接酶之间可能存在功能上的补偿和表达水平的相互调控。基于这些新的发现，本项目拟深入研究这三个连接酶在调控Oct4蛋白质水平，胚胎干细胞自我更新以及体细胞重编程过程中各自的作用及相互关系。同时，利用Wwp1、Wwp2与Itch基因双敲除或三敲除的小鼠模型，研究它们在小鼠发育过程中的作用与调控机制。该研究项目将有助于揭示Wwp1、Wwp2和Itch在早期胚胎发育过程中的重要生理功能。

Oct4, a core transcriptional factor, plays a pivotal role in regulating pluripotency and self-renewal of embryonic stem cells (ESCs), and its expression level determines the cell state and differentiation fate of ESCs. However, the molecular mechanisms by which Oct4 protein level is precisely controlled remains elusive. Previously, our study demonstrated that Wwp2 represses the transcriptional activity and protein level of Oct4 along with the induced differentiation process towards primitive endoderm. Later, we found that Wwp1 and Itch, E3 ubiquitin ligases, catalyze Oct4 ubiquitination specifically, and might maintain self-renewal of ESCs by modulating protein level and transcriptional activity of Oct4. Due to function compensation among Wwp1, Wwp2 and Itch, we will study how they coordinate to regulate the establishment and maintenance of pluripotency in ESC and induced reprogramming process. Furthermore, we plan to investigate whether Wwp1, Wwp2 and Itch regulate the protein level and transcriptional activity of Oct4 during the early embryo development process by utilizing the double or triple gene knockout mice. This study will help to unveil the regulatory function of Wwp1, Wwp2 and Itch- catalyzed ubiquitination on Oct4 during early embryo development, and open new avenues for ESC amplification and induced differentiation toward specific cell lineages.