Nucleocytoplasmic trafficking for regulation of defense signaling in plants | 植物核质转运与抗病防卫反应信号传导交叉调控

中国人. 摘　　要：核质转运过程是真核生物对信号传导进行精密调控的重要途径,核输入载体蛋白（importin,IMP）和核孔蛋白（nucleo-porin,Nup）对此承担重要功能。植物擅长使用这两类蛋白质对抗病防卫反应信号传导进行调控,影响多种激素信号传导通路。水杨酸、乙烯、茉莉酸是介导植物防卫反应的最重要的激素信号,水杨酸信号传导靠含锚蛋白序列的NPR1来调控系统性获得抗性（systemic acquired resistance,SAR）,并经常与乙烯或茉莉酸对抗,而茉莉酸与乙烯常常协作。已知完全测序的拟南芥基因组至少含有26种IMP基因和18种Nup基因。据他人和笔者最近研究,IMP和Nup基因至少分别有7种可影响拟南芥的抗病性,是SAR的必要因子。初步证明IMPα-3、Nup88和Nup96促进NPR1核质转运与SAR发生发展,而Nup98对SAR则有抑制作用。根据生物信息学,IMPα-3、Nup88、Nup96和Nup98基因不仅受水杨酸而且受乙烯和茉莉酸诱导,说明分子核质运输的竞争或协同作用可能是信号交叉调控的一个重要机制。

英语. Sophisticated nucleocytoplasmic trafficking is an important feature for fine-tuning signaling pathways in eukaryotic organisms.Importin（IMP）and nucleoporin（Nup）proteins are essential for the exchange of macromolecules across the nuclear envelope.Plants can use these proteins to dominate phytohormone signaling pathways that regulate defense responses to pathogens.The most important one of plant defensive pathways involves salicylic acid（SA）signal transduction.SA signaling activates the ankyrin-containing protein NRP1 to regulate systemic acquired resistance（SAR）,and often antagonizes ethylene or jasmonic acid（JA）signaling.In Arabidopsis,at least 7 IMP and 7 Nup genes are involved in nucleocytoplasmic trafficking of SA signaling components associated with SAR.Nuclear transportation of NPR1 requires IMPα-3,Nup88,and Nup96,and this feature results in the expression of SAR marker genes and the development of SAR.Inversely,Nup98 is suppressive to both SAR and the expression of SAR marker genes.Bioinformatics searches show that IMPα-3,Nup88,Nup96,and Nup98 genes contain cis-acting elements that are inducible not only by SA but also by ethylene and JA.This conforms to the antagonism between SA and ethylene or JA in plant defense responses,suggesting that the competition or cooperation in nucleocytoplasmic trafficking contributes to crosstalk of defense pathways in plants.