一个核质穿梭蛋白在FERONIA信号网络中的功能

The mechanism of cell growth is not only a theory focus in cell signaling transduction, but also a technical bottleneck remaining to be solved in the application fields for agriculture and forestry. Recently, the network of RALF1 peptide signaling and its receptor complex FER/RIPK is becoming a research hotspot in plant cell growth field. But events of this network that regulate gene expression in the nucleus are still unknown. Applicant has found that FER can interact with EBP1, a nucleo-cytoplasmic shuttling protein that has role in cell growth, and RALF1 enhances the protein content of EBP1, which in turn accumulating EBP1 in the nucleus. EBP1 associates with some previous identified RALF1-regulated genes promoter and alter gene expression. Furthermore, EBP1 appears to inhibit RALF1 peptide response. Based on these data, this application will explore: (1) the detailed biochemical mechanisms of FER-EBP1 interaction; (2) the mechanisms that RALF1 peptide uses to regulate the content and nucleo-cytoplasmic shuttling of EBP1; (3) the targets of EBP1 in nucleus and the role of EBP1 in RALF1 response. This application not only promotes to understand the molecular mechanisms of receptor-like kinase-mediated signaling transduction, but also improves the comprehension of RALF1-FER/RIPK network’s function in cell growth. Our research conclusions will provide a new genetic resource for the crops’ molecular breeding.

植物细胞生长机制不仅是细胞信号转导领域关注度极高的理论焦点，也是农、林等应用领域亟需解决的技术瓶颈。多肽信号RALF1及其受体激酶FER/RIPK复合体组成的信号网络是近年植物细胞生长研究中的热点与重点，但该信号网络在细胞核内的事件尚无相关报道。申请人发现FER与一个调节细胞生长的核质穿梭蛋白EBP1相互作用，RALF1上调EBP1的蛋白量并使其在核内积累，影响EBP1对下游靶标基因的启动子结合, EBP1负调节RALF1信号。基于此，本项目拟探讨（1）FER与EBP1相互作用的精细生化机制；（2）RALF1对EBP1蛋白含量及核质穿梭的调节机制；（3）EBP1在细胞核中的靶标基因，及在RALF1信号响应中的功能。本研究不仅促进对受体激酶介导的细胞信号转导机制的认识，也将促进对RALF1-FER/RIPK信号网络调节细胞伸长机制的理解, 有望为优良农作物的分子育种设计提供新的遗传资源。

植物的生长发育受到外界环境的调控，植物细胞膜上的受体蛋白激酶在感知外界信号、调控植物生长发育过程中起着重要的作用，但细胞膜感受信号后，如何将信号传递到细胞核，进而调控基因的表达及植物的生长发育，目前知之甚少。本课题研究发现受体蛋白激酶FERONIA（FER）能与EBP1蛋白相互作用并磷酸化EBP1蛋白，项目组进一步鉴定了EBP1的磷酸化位点。多肽RALF1处理能促进EBP1的mRNA翻译，提高EBP1蛋白质的积累，RALF1-FER介导的EBP1磷酸化可促进EBP1进入细胞核，进而调控下游基因的表达，精细地调控植物的生长和发育，目前初步鉴定到四个受EBP1直接绑定和调控的靶标基因。本项目的研究结果揭示了一条全新的细胞膜-细胞核信号转导通路，有望为农作物的优良设计育种提供新的基因资源和思路。