长链非编码RNA - COOLAIR在春化作用过程中的调节机制和功能的研究

The most majority of transcriptome (over 90%) in higher eukaryotes is non-coding RNA, including tens of thousands of long non-coding RNA (lncRNA). However, their transcriptional regulation mechanism and biological function study are very limited. A set of short cold (2-3 weeks) induced long anti-sense intragenic RNAs (COOLAIR), which can be transcribed from the 3’ end of the central flowering repressor gene FLC, were found by previous study. COOLAIR can transcriptionally repress FLC expression probably through chromatin modification related mechanisms. A forward genetic screening was undertaken to identify COOLAIR regulators and explore its function on FLC sense regulation. Through this screening, a mutant, in which COOLAIR can be specifically over induced by short cold, was identified. A rough characterization found FLC cannot be effectively repressed by the short cold treatment in this mutant. This study will clone responsible gene, and further investigate the mechanism underlying cold induced COOLAIR expression. Meanwhile, we will also explore the possible mechanism in COOLAIR mediated FLC repression. In this study, we aim to explore the regulation mechanism of cold induced lncRNA COOLAIR and its function on FLC regulation. It will be beneficial for other environmental regulated lncRNA researches. We expect to explore new insight to the function of non-coding transcriptome, and also publish 1-2 high impact research papers. More importantly, we hope to get 2-4 highly creative graduate students from this study.

高等生物超过90%的转录组为非编码RNA，包括数以万计的长链非编码RNA，但是它们转录活性的调节和生物学功能的研究还比较欠缺。拟南芥中心开花抑制因子FLOWERING LOCUS C（FLC）3’末端能够转录出一系列的被早期春化处理（2-3周）诱导表达的长链非编码反义RNA（COOLAIR），并可能通过染色质修饰相关的调控机制抑制FLC的转录。遗传筛选发现了一个短时间春化处理过量诱导表达COOLAIR的突变体，初步的研究结果表明早期的春化处理不能有效抑制突变体中FLC的表达。我们将用该材料研究低温处理诱导COOLAIR的调节机制及其对FLC的调控功能，从而揭示低温环境对COOLAIR的调节机制和生物学功能，为其它环境因素相关的lncRNA调节机制的研究提供参考，并进一步的揭示非编码转录组的调节机制和功能。并预计通过本研究发表1-2篇高水平的研究论文，培养研究生2-4名。

高等生物的转录本中存在大量的长链非编码RNA，它们在激素信号转导、环境响应、生长发育等过程中发挥了重要作用。拟南芥中心开花抑制因子FLOWERING LOCUS C（FLC）3’末端转录出一系列的长链非编码反义RNA，统称为COOLAIR。低温诱导特定剪接形式COOLAIR的富集，并通过染色质修饰相关的转录调控机制抑制FLC的转录，调控开花时间。但是低温诱导COOLAIR表达的机制还缺乏研究。利用遗传筛选，我们克隆了一个特异性调控COOLAIR低温响应的因子SMU1。一方面，SMU1和PAF1复合体相互作用，在低温条件下抑制Pol II的活性，限制COOLAIR的转录活性；另一方面，SMU1作为剪接复合体B的组分，结合正在转录的COOLAIR RNA的5’端，促进近端内含子的剪接。二者共同促进近端内含子剪接的COOLAIR的产生，抑制FLC的表达。因此，本研究揭示了SMU1通过转录共剪接的方式维持低温时COOLAIR的转录水平和剪接形式，抑制FLC的转录，促进开花的分子机制。.同时，我们全面解析了短时间和长时间低温条件下冬性拟南芥的转录景观，预测了长链非编码RNA和转录因子在低温响应过程中的调控网络。我们还揭示了复制蛋白RPA2A和PRC2协同调控拟南芥开花时间的分子机制。这些研究丰富了拟南芥开花时间调控的分子网络，为全面揭示开花时间的调控机制提供了新的研究成果。