Regulation of transcription termination and its link in mRNA surveillance

描述（由申请人提供）：精确调控转录终止对细胞生长和存活至关重要。而过早停止转录可能产生截断和有缺陷的转录本；停止得太晚可能会破坏下游相同取向基因的调控，产生针对相反取向基因的反义RNA。这两种结果都会对基因表达产生重大影响。因此，转录终止缺陷与各种人类疾病（如血栓病、地中海贫血和癌症）有因果关系并不奇怪。我们之前在最近的一项研究中证明，mRNA帽结合蛋白复合物与抗终止因子Npl3p一起调节转录终止。在本项目中，我将继续利用遗传和分子生物学相结合的方法阐明出芽酵母模式生物真核转录终止的机制。我的研究重点是通过Npl3p调控真核生物转录终止，以及真核生物转录终止与RNA监视的功能偶联。第一部分，我将定义Npl3p翻译后修饰对其抗终止活性的影响。对于第二部分，我将探讨转录终止和RNA监视的细胞机制如何在功能上相互耦合。特别是，我将研究核外泌体Rrp6p的共转录募集。由于转录终止的基本重要性以及从酵母到人类的转录终止机制的高度保守性，我们的发现将对由转录终止缺陷引起的人类疾病具有重要意义。

DESCRIPTION (provided by applicant): Precise regulation of transcription termination is essential to cellular growth and survival. While premature stopping of transcription may produce truncated and defective transcripts; stopping too late may disrupt the regulation of downstream genes in the same orientation and generate antisense RNA against genes in the opposite orientation. Either outcome would have significant impact on gene expression. Thus, it is not surprising that transcription termination defects are causally associated with various human diseases, such as thrombophilia, thalassemia and cancer. We have previously demonstrated in a recent study that the mRNA cap-binding protein complex functions in conjunction with antitermination factor Npl3p to regulate transcription termination. In this project, I will continue to shed light on the mechanisms of eukaryotic transcription termination in the model organism of budding yeast using a combination of genetic and molecular biological methods. My study will focus on the regulation of eukaryotic transcription termination through Npl3p and the functional coupling of eukaryotic transcription termination with RNA surveillance. For the first part, I will define the influence of post-translational modification of Npl3p on its antitermination activity. For the second part, I will explore how cellular machineries of transcription termination and RNA surveillance are functionally coupled with each other. Particularly, I will investigate cotranscriptional recruitment of nuclear exosome Rrp6p. Because of the fundamental importance of transcription termination and high degree of conservation of transcription termination machineries from yeast to human, our findings will have important implications in human diseases caused by transcription termination defects. PUBLIC HEALTH RELEVANCE: Transcription termination is critical for gene expression, as defects in this process can produce mRNA transcripts that are unstable or encode defective proteins, and can also interfere with proper expression of neighboring genes. Accordingly, such defects are associated with some human diseases, such as thrombophilia, thalassemia and cancer. In addition, transcription termination is an important means for gene regulation in viruses including HIV. It is crucial, therefore, to develop a complete understanding of the mechanism and regulation of transcription termination. This project aims to derive new insight into the regulation of transcription termination and its link in mRNA surveillance using budding yeast as a model. Because the cellular machineries for transcription termination are highly conserved from yeast to human, our findings will have important implications in human biology and medicine.