RNA聚合酶II CTD 相互作用组功能调控的分子机理

The CTD (C-terminal domain) of RNA polymerase II serves as an important recruiting platform and function-coordination hub for protein complexes that regulate transcription, RNA processing and chromatin structure. CTD consists of multiple heptapeptide repeats and non-repeat sequences. The prevalent view in the field is that the modification patterns of heptapeptide repeats dictate the specificity of the CTD signaling pathway. However, recent studies suggest that CTD interactomes may exist as highly organized super protein complexes, in which many reversible reactions take place under strict spatial-temporal control. Therefore, signals from repeating sequence units alone seem to be not sufficient to direct such precise and complicate assembly processes. Our preliminary studies revealed an important function of the CTD non-repeat sequence in recruiting CTD binders, which provided critical evidences to explore additional factors that contribute to the CTD signaling pathway. We hypothesize that the assembly of CTD interactomes on a repeating sequence platform is directional, cross-talks between CTD-associated factors and their recognition of CTD modifications collectively determine their Pol II tethering and functional specificity. We will address the following scientific questions: 1) to determine how CTD non-repeat sequences and their modifications control downstream factor recruitment; 2) to elucidate the mechanism by which cross-talks between CTD binders that share the CTD platform influence their functionalities; 3) to characterize tumorigenic interactions between CTD binders and identify key interfaces as new drug targets for future lung cancer therapeutics.

对于参与转录调控和染色体调节的复合物，RNA聚合酶II CTD (C端结构域) 是一个重要的招募平台和调节枢纽。CTD由非重复序列和若干七肽重复序列组成。CTD信号长期被归结于重复序列的修饰模式。然而近期研究发现CTD相互作用组是高度有序的超级复合体，其催化的可逆反应受到时空上的严格调控，说明修饰的重复序列本身不足以指挥如此精密的组装。寻找新的调控因素成为转录调控研究的前沿。基于我们前期关于CTD非重复序列功能的发现，我们认为: CTD相互作用组在重复序列上的组装是具有方向性的，CTD结合因子对于重复序列修饰的识别和它们之间的交叉作用共同决定了招募特异性和功能调节。 本项目拟解决以下科学问题：1) 阐明非重复序列及其修饰招募CTD结合因子的分子机理；2) 决定CTD结合因子在CTD平台上的交叉作用对其功能调控的影响；3) 鉴定癌症诱发CTD结合因子相互作用界面, 开发新的肺癌治疗药物靶点。

RNA聚合酶II CTD (C端结构域) 是招募转录因子及染色体重塑复合物的关键平台和重要调节枢纽。传统的CTD重复序列修饰模式理论不足以解释CTD精密的组装及严格的时空调控机制。因此，利用先进的体外组装及转录体系揭示影响CTD功能新的调控因素及调控机制成为转录调控研究的前沿。我们基于前期关于CTD非重复序列功能的研究提出的科学假说认为，CTD相互作用组在重复序列上的组装是具有方向性的，并且CTD结合因子对于重复序列修饰的识别和它们之间的交叉作用共同决定了招募特异性和功能调节。.本项目在执行过程中，针对提出的科学问题，包括有关CTD结合因子招募机制，CTD结合因子在CTD平台互作对其功能的调控等方面均取得重要研究进展。为进一步探索真核生物转录调控机制提供了新思路及理论支撑。我们的研究成果包括：利用独特的体外组装及转录体系阐明了转录过程中RNA结合蛋白如何通过与CTD的共同相分离调节转录活性；在哺乳动物细胞中建立了诱导型快速降解体系，将CTD平台的重要锚定蛋白Spt6对转录的调控机制从范式生物酵母推广到高等动物；我们的相关研究还揭示了表观遗传修饰及相关酶在高等动物发育，组织再生和疾病中的调控机制。.本项目基本完成了预期目标， 研究成果包括发表于Nature Chemical Biology、PNAS、及Cell Reports等多篇研究论文。