Development：北京林业大学丨固醇调控FLS2蛋白胞吞的新机制（钙信号）

期刊：Development

主题：固醇调控FLS2蛋白胞吞的新机制（钙信号）

标题：Sterols regulate endocytic pathways during flg22-induced defense responses in Arabidopsis

影响因子：5.413

检测指标：Ca2+流速

检测样品：拟南芥叶片

Ca2+流速流实验处理方法：

7日龄拟南芥，0.1 μM flg22处理

Ca2+流速流实验测试液成份：无
推荐测试液：0.1mM CaCl2，pH 6.0

作者：北京林业大学林金星、李晓娟

英文摘要

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.

中文摘要（谷歌机翻）

植物跨膜受体激酶FLAGELLIN SENSING 2（FLS2）对于先天免疫至关重要。尽管以前的研究已经报道了通过网格蛋白介导的途径介导的FLS2介导的信号转导和胞吞作用，但尚不清楚其他内吞途径是否会影响FLS2介导的防御反应。

在这里，我们显示拟南芥的甾醇缺乏突变体类固醇甲基转移酶1在鞭毛蛋白衍生的肽flg22诱导的免疫反应中显示缺陷。可变角度全内反射荧光显微镜（VA-TIRFM）结合单粒子跟踪显示，在处理的细胞中，FLS2-GFP的时空动态在毫秒级变化，质膜上的FLS2-GFP停留时间增加与未经处理的对应物相比，含固醇提取剂。

我们进一步证明，flg22诱导的FLS2聚集和内吞涉及与固醇相关的内吞途径，这不同于网格蛋白介导的途径。此外，flg22通过固醇相关途径增强了FLS2-GFP与膜微区标记Flot  1-mCherry和FLS2内吞的共定位。这表明植物可以通过调节两种不同的内吞途径来响应病原体侵袭。

两者合计，我们的结果表明固醇稳态在flg22诱导的植物防御反应中的关键作用。

结果表明：相比野生型，smt1（甾醇甲基转移酶1）突变体表现出迅速且强烈的Ca2+吸收速率高于根冠（R0和R1），低于根伸长区（R2）。增加，说明突变体对于flg22更为敏感。smt1突变没有改变FLS2的同源寡聚状态，但影响FLS2簇形成。smt1突变体中FLS2的内吞功能受到损伤。由上述结果得到一个假设，即甾醇相关的内吞途径对于flg22诱导的FLS2动力学和植物防御至关重要。