Sterols regulate endocytic pathways during flg22-induced defense responses in Arabidopsis
Sterols regulate endocytic pathways during flg22-induced defense responses in Arabidopsis
复制标题
甾醇在拟南芥中 flg22 诱导的防御反应过程中调节内吞途径
DOI：
10.1242/dev.165688
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发表时间：
2018-10-01
期刊：
影响因子：
4.6
通讯作者：
Lin, Jinxing
中科院分区：
文献类型：
--
作者：
Cui, Yaning;Li, Xiaojuan;Lin, Jinxing
摘要 植物跨膜受体激酶 FLAGELLIN SENSING 2 (FLS2) 对于先天免疫至关重要。尽管之前的研究报道了FLS2介导的信号转导和通过网格蛋白介导的途径进行内吞作用，但其他内吞途径是否影响FLS2介导的防御反应仍不清楚。在这里，我们发现拟南芥甾醇缺陷突变型类固醇甲基转移酶 1 在鞭毛蛋白衍生肽 flg22 诱导的免疫反应中表现出缺陷。可变角度全内反射荧光显微镜（VA-TIRFM）与单粒子追踪相结合表明，与未处理的细胞相比，用甾醇提取试剂处理的细胞中FLS2-GFP的时空动态在毫秒级上发生变化，并且FLS2-GFP在质膜上的停留时间增加。我们进一步证明 flg22 诱导的 FLS2 聚类和内吞作用涉及甾醇相关的内吞途径，这与网格蛋白介导的途径不同。此外，flg22 增强了 FLS2-GFP 与膜微域标记 Flot 1-mCherry 的共定位，并通过甾醇相关途径增强了 FLS2 内吞作用。这表明植物可能通过调节两种不同的内吞途径来应对病原体的攻击。综上所述，我们的结果表明甾醇稳态在 flg22 诱导的植物防御反应中发挥关键作用。摘要：单颗粒分析表明，在拟南芥中，FLS2 在质膜中的扩散和 FLS2 内化在甾醇缺陷突变体中发生了改变。
ABSTRACT The plant transmembrane receptor kinase FLAGELLIN SENSING 2 (FLS2) is crucial for innate immunity. Although previous studies have reported FLS2-mediated signal transduction and endocytosis via the clathrin-mediated pathway, whether additional endocytic pathways affect FLS2-mediated defense responses remains unclear. Here, we show that the Arabidopsis thaliana sterol-deficient mutant steroid methyltransferase 1 displays defects in immune responses induced by the flagellin-derived peptide flg22. Variable-angle total internal reflection fluorescence microscopy (VA-TIRFM) coupled with single-particle tracking showed that the spatiotemporal dynamics of FLS2-GFP changed on a millisecond time scale and that the FLS2-GFP dwell time at the plasma membrane increased in cells treated with a sterol-extracting reagent when compared with untreated counterparts. We further demonstrate that flg22-induced FLS2 clustering and endocytosis involves the sterol-associated endocytic pathway, which is distinct from the clathrin-mediated pathway. Moreover, flg22 enhanced the colocalization of FLS2-GFP with the membrane microdomain marker Flot 1-mCherry and FLS2 endocytosis via the sterol-associated pathway. This indicates that plants may respond to pathogen attacks by regulating two different endocytic pathways. Taken together, our results suggest the key role of sterol homeostasis in flg22-induced plant defense responses. Summary: Single-particle analysis reveals that, in Arabidopsis, FLS2 diffusion in the plasma membrane and FLS2 internalization are altered in a sterol-deficient mutant.