SKIP调控拟南芥开花时间的分子机理

SKIP encodes a conserved SNW domain-containing protein. It has been reported that SKIP functions as splicing factor or transcriptional activator/repressor through interacting with histone acetyltransferase/histone deacetylase in yeast and/or mammals. The homolog of SKIP in Arabidopsis, AtSKIP, is the component of the spliceosome and involved in the control of the circadian clock through regulating the alternative splicing of PRR7 and PRR9. In addition to the lengthened period of the circadian clock defect, skip-1 mutation also confers early flowering and insensitive to photoperiod phenotypes, indicating that SKIP represses flowering in Arabidopsis. However, the molecular and biochemical mechanisms on how SKIP regulates flowering time remain obscure. To explore the regulatory mechanisms of SKIP on flowering time control, early flowering and photoperiod insensitive mutant, skip-1 will be applied in this study. The target gene through which SKIP regulates flowering time will be identified by using quantitative RT-PCR, RNA-highthroughput sequencing. Furthermore, the molecular mechanisms on how the target gene regulated by SKIP will be investigated through transgenic technology, genetic analysis, quantitative RT-PCR, cDNA library screening and chromatin immunoprecipitation-sequencing techniques. The findings of the study will provide sound theoretical and practical foundation for the functions of SKIP in flowering time control and broad our understanding of the essential roles for SKIP in plant development.

SKIP编码在进化上保守、包含有SNW结构域的蛋白质。在酵母和/或哺乳动物中，SKIP是剪切因子，并且通过和组蛋白乙酰转移酶或脱乙酰化酶相互作用，作为转录的共激活或抑制因子，调节靶基因的表达。拟南芥中的SKIP是剪切复合体的组分，它通过影响PRR7和PRR9的可变剪切，参与生物钟的调控。除了生物钟的节律周期变长的缺陷外，skip-1突变体还具有开花时间提前的表型，但是早花的分子机理尚不清楚。为了诠释SKIP参与开花时间调控的分子机制，本研究拟用早花突变体skip-1为试材，利用包括荧光定量PCR、RNA高通量测序等技术，寻找SKIP参与开花时间调控的靶基因；并利用转基因、遗传分析、荧光定量PCR、cDNA文库筛选和染色质免疫共沉淀-测序等技术，深入分析SKIP调控靶基因的遗传、分子和生化机制，为进一步探明SKIP调控开花时间的分子机制及其在植物生命过程中的作用提供详实的理论和实践依据。

在拟南芥中SKIP是剪接复合体的组分，参与生物钟和耐盐性的调控。但是，SKIP参与开花期调控的分子机制尚不清楚。本研究以早花突变体skip-1为试材，利用现代生物技术手段，研究了SKIP参与开花时间调控的分子和生化机制。..（1）skip-1突变体表现为在长、短日照条件下均为早花。说明SKIP是开花抑制因子。（2）skip-1抑制开花抑制因子FLC及其同源基因MAF1、MAF4、MAF5的表达。skip-1突变体中FLC及其同源基因的表达降低，开花促进因子FT、TSF和SOC1的表达升高，促进拟南芥开花。（3）SKIP是SWR1染色质重塑复合体的组分SEF pre-mRNA的可变剪接所必需的。skip-1突变导致SEF pre-mRNA的可变剪接障碍，进而使SEF功能型mRNA的水平降低，非功能型mRNA的水平提高。（4）SKIP具有结合SEF pre-mRNA的能力。RNA免疫共沉淀（RIP）的结果表明，SKIP可以结合SEF pre-mRNA，参与SEF pre-mRNA可变剪接的调控。（5）skip-1突变导致FLC、MAF4、MAF5染色质中H2A的变种H2A.Z的富集水平降低。染色质免疫共沉淀 (ChIP) 分析表明，和野生型相比skip-1突变降低FLC、MAF4、MAF5染色质中H2A.Z的富集水平，从而抑制它们的表达，促进开花。..综上所述，SKIP通过结合SWR1-C复合体的组分SEF的pre-mRNA，调控其可变剪接，促进SEF的表达；进而促进H2A.Z在开花抑制因子FLC、MAF4、MAF5染色质中富集，激活它们的表达；FLC、MAF4、MAF5的上调表达，降低开花促进因子SOC1，FT，和TSF的表达，延迟拟南芥开花。本研究诠释了SKIP调控开花时间的分子机制，为进一步揭示SKIP在植物生命过程中的作用提供了详实的理论和实践依据。..在该项目的资助下，项目主持人王晓雪教授为通讯作者，在BMC Biology，Plant Biotechnology Journal，Critical Reviews in Plant Sciences，Journal of Experimental Botany，Plant and Cell Physiology 等杂志上发表SCI论文6篇，累计影响因子为34.155；其中第一标注5篇、第二标注1篇。