转录延伸因子SPT6L调控转录起始的分子机理研究

基因转录过程中，起始向延伸的转换不仅能调控基因的表达量，而且是决定基因是否表达的重要节点。当前，对于该节点调控机制的研究目前主要集中在对RNA聚合酶在近端启动子停滞以及解析转录复合体在起始与延伸阶段上的不同蛋白组成上。但申请人前期的研究发现经典的转录延伸因子SPT6L能不依赖于RNA聚合酶II结合到转录起始位点，并促进RNA聚合酶II在基因上的累积，暗示SPT6L有可能在协调转录起始和延伸过程中发挥关键作用。通过前期对于生物信息学和蛋白互作的分析研究，我们找到了2个同源且与SPT6L互作的类染色质重塑因子chromatin remodeler 1(CHR1)和CHR2。本项目拟通过综合运用分子生物学、遗传学和生物信息学的手段，解析是否CHR1和CHR2通过SPT6L参与转录过程，并进一步阐明SPT6L招募染色质重塑因子调控转录起始的分子机制，为研究起始向延伸转换提供了新的研究方向。

The transition of transcription initiation to elongation serves as an essential step to regulate the level of transcription and even determine the fate of transcription. Currently, our understanding to this transition mainly sources from the researches on promoter-proximal pausing and identifying different components of transcription machinery in initiation and elongation. Our previous study reveals that the classical elongation factor, SPT6L, can be recruited to transcription staring site (TSS) and promotes the entry of RNA polymerase II (RNAPII) into gene body. Classically, the dependence of SPT6L on RNAPII is important to the association between SPT6L and transcribing genes. However, we found that this TSS recruitment of SPT6L is independent on RNAPII, suggesting that the potential roles of SPT6L in the coordination of transcription initiation and elongation. Our preliminary results revealed that two homologs of chromatin remodeler, CHR1 and CHR2, shared the similar genome-wide binding patterns around TSS to SPT6L’s. And, co-immunoprecipitation assay can successfully detect the interaction between CHR1 and SPT6L. These results suggesting that SPT6L may recruit CHR1 and CHR2 during transcription initiation. In this principle, we propose to combine molecular biology, genetics, and bioinformatics to investigate whether CHR1 and CHR2 is involved in transcription process, uncover the molecular mechanism of SPT6L in regulation of transcription initiation through the recruitment of chromatin remodelers. This study aims to provide new an angle to investigate the transition.