The role of mRNA 5' end capping in the transcriptional regulation of gene expression in eukaryotic cells.

5‘RNA m7G帽是RNA聚合酶II依赖(POL II)转录本的重要修饰。有效的信使核糖核酸封顶对于信使核糖核酸的稳定性至关重要，因为它能保护核糖核酸不被5‘-3’降解。CAP还可以作为CAP结合复合体(CBC)的平台，CBC是细胞RNA代谢所必需的，包括核输出、降解和翻译。虽然m7G帽在mRNA的生物发生中具有关键功能，但人们对其在转录和最终基因表达中的直接作用知之甚少。以往的报道表明，mRNA封顶缺陷可能会影响转录起始到延伸的转变，或者触发转录提前终止。因此，该项目将在模式生物酿酒酵母中研究mRNA帽、帽酶和帽过程如何调控真核细胞的转录和RNA合成。学生将使用染色质免疫沉淀(CHIP-SEQ)分析来测试POL II磷酸异构体的基因组位置，以及对帽缺陷细胞中的稳态(RNA-SEQ和直接RNA-SEQ)和新生RNA(4TU RNA-SEQ)的RNA分析。这些方法将全面分析m7G帽子和帽子如何影响真核细胞的核RNA生物学。该项目的结果将揭示RNA帽是否以及如何与5‘-3’共转录降解有关，并将定义POL II转录基因的封顶、转录进程和转录终止之间的相关性。

The 5' RNA m7G cap is an essential modification of the RNA Polymerase II-dependent (Pol II) transcripts. An efficient mRNA capping is crucial for mRNA stability as it protects the RNA from 5'-3' degradation. The cap functions also as a platform for the Cap Binding Complex (CBC) which is essential for cellular RNA metabolism including nuclear export, degradation, and translation. Although the m7G cap has a crucial function in the mRNA biogenesis, very little is known about its direct role in transcription and ultimately, in gene expression. Previous reports indicate that defects in mRNA capping may affect the transition from transcription initiation to elongation or trigger premature transcription termination. Thus, the project will investigate in the model organism Saccharomyces cerevisiae how the mRNA cap, the capping enzymes and the capping process regulate transcription and RNA synthesis in eukaryotic cells. The student will employ chromatin immunoprecipitation (ChIP-seq) analysis to test genomic positions of Pol II phosphoisoforms as well as RNA analyses of steady-state (RNA-seq and direct RNA-seq) and nascent RNA (4tU RNA-seq) in cap-deficient cells. These approaches will provide a comprehensive analysis of how m7G cap and the capping impact nuclear RNA biology in eukaryotic cells. The outcomes of this project will reveal if and how RNA cap is related to 5'-3' co-transcriptional degradation and will define a correlation between capping, transcription progression and transcription termination of Pol II-transcribed genes.