Investigating the role of Chromatin in coupling RNA quality control to transcription

“RNA生命周期”的质量控制对细胞稳态至关重要。为了避免mRNA合成异常，RNA聚合酶II （RNA Pol II）通常会过早终止转录，导致细胞核内新生RNA转录物的降解。表征RNA降解的途径在分子细节上是已知的，然而调节转录终止的机制尚不清楚。此外，目前还不清楚这些机制是否在整个真核生物中都是保守的。真核生物的转录发生在浓缩的动态核蛋白染色质结构的连接中。众所周知，RNA Pol II在转录过程中经常停顿，在酿酒酵母中，这种特定DNA序列的停顿与RNA监视因子和转录终止因子装载到mRNA转录物上有关。INO80，一种atp依赖性的染色质重塑剂，控制组蛋白变体H2A的结合。Z，已被发现促进过早终止，并能够抵消RNA Pol II暂停位点的积累。H2A的缺失。Z已被证明会导致转录过早终止的缺陷。此外，在截断组蛋白H3的大量翻译后修饰的n端尾部后，观察到早期终止增加，表明其在控制转录过早终止中起重要作用。该项目将研究染色质如何决定RNA Pol II是否进入生产性延伸，或被移除导致过早终止。具体来说，是组蛋白变体H2A。Z在这一过程中的作用将被探索，同时使用人类基因同源物和癌细胞系来确定终止控制的保守机制。

Quality control of the 'RNA life-cycle' is crucial for cellular homeostasis. To avoid abnormal mRNA synthesis, typically RNA polymerase II (RNA Pol II) will prematurely abort transcription, leading to the degradation of the nascent RNA transcript within the nucleus.The pathway characterising the degradation of RNA is known in molecular detail, however the mechanisms which regulate the termination of transcription are unclear. Additionally, it is also unclear whether these mechanisms are conserved throughout eukaryotes. Transcription within eukaryotes occurs within the connect of the condensed, dynamic nucleoprotein chromatin structure. RNA Pol II is known to pause frequently during transcription, and within S. cerevisiae, this pausing at specific DNA sequences is associated with the loading of both RNA surveillance factors and transcription termination factors onto the mRNA transcript. INO80, an ATP-dependant chromatin remodeller which controls incorporation of the histone variant H2A.Z, has been found to promote premature termination and is able to counteract the accumulation of RNA Pol II pausing sites. Deletion of H2A.Z has shown to lead to defects in premature termination of transcription.Furthermore, following truncation of the heavily post-translationally modified N-terminal tail of the histone H3, increased early termination is observed, indicating an important role in controlling premature termination of transcription. This project will investigate how Chromatin dictates whether RNA Pol II progresses into productive elongation, or is removed leading to premature termination. Specifically, the histone variant H2A.Z's role in this process will be explored, along with the use of human-gene orthologues and cancer-cell lines to identify conserved mechanisms of termination control.