Phosphatidic Acid Counteracts S-RNase Signaling in Pollen by Stabilizing the Actin Cytoskeleton
Phosphatidic Acid Counteracts S-RNase Signaling in Pollen by Stabilizing the Actin Cytoskeleton
复制标题
磷脂酸通过稳定肌动蛋白细胞骨架来抵消花粉中的 S-RNase 信号传导
DOI：
10.1105/tpc.18.00021
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发表时间：
2018-05-01
期刊：
影响因子：
11.6
通讯作者：
Wu, Juyou
中科院分区：
文献类型：
--
作者：
Chen, Jianqing;Wang, Peng;Wu, Juyou
在梨自交不亲和反应中，PbrS-RNase直接解聚肌动蛋白细胞骨架，促进磷脂酸的产生，对不亲和花粉管起保护作用。S-RNase是梨自交不亲和性的雌性决定因子。在易位到花粉管后，S-RNase以S-单倍型特异性方式降解rRNA并诱导花粉管死亡。在这项研究中，我们发现肌动蛋白细胞骨架是P. bretschneideri S-RNase（PbrS-RNase）的靶点，并揭示了一种机制，涉及磷脂酸（PA），并保护花粉管免受PbrS-RNase的细胞毒性。PbrS-RNase与PbrActin 1以不依赖于S单倍型的方式直接相互作用，导致肌动蛋白细胞骨架脱镁并促进自交不亲和花粉管中的细胞程序性死亡。PbrS-RNase的Pro-156是PbrS-RNase-PbrActin 1相互作用所必需的，并且PbrS-RNase的肌动蛋白细胞内解聚功能不需要其RNase活性。PbrS-RNase的细胞毒作用增强了不亲和花粉管中磷脂酶D（PbrPLDδ1）的表达，导致PA水平的增加。PbrPLDδ1衍生的PA最初阻止PbrS-RNase引起的肌动蛋白细胞骨架的解聚，并延迟导致花粉管死亡的SI信号。这项工作提供了深入了解的编排的S-RNase为基础的SI响应，其中PA水平的增加最初发挥保护作用，在不兼容的花粉，直到持续的PbrS-RNase活性达到不归点和花粉管生长停止。
In the self-incompatibility response in pear, PbrS-RNase directly depolymerizes the actin cytoskeleton and promotes phosphatidic acid production, which plays a protective role in incompatible pollen tubes. S-RNase is the female determinant of self-incompatibility (SI) in pear (Pyrus bretschneideri). After translocation to the pollen tube, S-RNase degrades rRNA and induces pollen tube death in an S-haplotype-specific manner. In this study, we found that the actin cytoskeleton is a target of P. bretschneideri S-RNase (PbrS-RNase) and uncovered a mechanism that involves phosphatidic acid (PA) and protects the pollen tube from PbrS-RNase cytotoxicity. PbrS-RNase interacts directly with PbrActin1 in an S-haplotype-independent manner, causing the actin cytoskeleton to depolymerize and promoting programmed cell death in the self-incompatible pollen tube. Pro-156 of PbrS-RNase is essential for the PbrS-RNase-PbrActin1 interaction, and the actin cytoskeleton-depolymerizing function of PbrS-RNase does not require its RNase activity. PbrS-RNase cytotoxicity enhances the expression of phospholipase D (PbrPLDδ1), resulting in increased PA levels in the incompatible pollen tube. PbrPLDδ1-derived PA initially prevents depolymerization of the actin cytoskeleton elicited by PbrS-RNase and delays the SI signaling that leads to pollen tube death. This work provides insights into the orchestration of the S-RNase-based SI response, in which increased PA levels initially play a protective role in incompatible pollen, until sustained PbrS-RNase activity reaches the point of no return and pollen tube growth ceases.