真核生物基因表达在转录及转录后水平受到严格调控，从而精确控制mRNA及蛋白的水平来调节机体发育。RNA加工是基因转录后调控的关键步骤，包括对初始转录产物5’加帽，剪接和3’末端形成。PAF1c在进化过程中保守，与RNA聚合酶II一起负责基因转录延伸和终止。植物体系中已有结果表明PAF1c通过影响组蛋白修饰调控FLC转录进而调节拟南芥开花。但PAF1c是否参与转录后基因表达调控还未见报道。我们前期结果检测到拟南芥PAF1c可影响一些基因的3’末端形成，暗示PAF1c可能参与植物前体mRNA 3’末端形成。本项目拟进一步检测拟南芥PAF1c对基因组范围内mRNA 3’末端形成影响，探讨其调控基因3’末端形成的分子机制，并证实PAF1c是否能够通过调控基因的3’末端形成影响植物某个或某些发育过程。研究结果将完善PAF1c调控植物基因表达的分子机制，还将丰富前体mRNA 3’末端形成的分子机制。

Gene expression in eukaryotes is tightly controlled through regulation at both the transcriptional and post-transcriptional levels. RNA processing, which includes the 5' capping, splicing, and 3' end formation of pre-mRNA molecules, is a key step in the post-transcriptional regulation of gene expression. PAF1c is an evolutionarily conserved complex that has been proposed to be associated with RNA polymerase II during transcriptional elongation and termination in yeast and animal cells. In plants, PAF1c is reportedly involved in the regulation of flowering time by promoting the histone modification of chromatin and the transcription of FLC/MAFs in Arabidopsis. However, whether PAF1c is involved in the regulation of gene expression at the post-transcriptional level is unknown. We previously showed that PAF1c regulates 3' end formation for several genes. The proposed work will examine the role of PAF1c in the regulation of 3' end formation at the whole-genome scale, and reveal how PAF1c regulates 3' end formation during transcription termination in Arabidopsis. We will also examine whether PAF1c mediates a specific developmental process by regulating the 3' end formation of genes involved in that process. The results of the proposed work will not only uncover a new mechanism whereby PAF1c regulates gene expression at the post-transcriptional level, they will also provide new insight into the regulatory mechanism of mRNA 3' end formation in plants.