Plant Rho GTPase signaling promotes autophagy
Plant Rho GTPase signaling promotes autophagy
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植物 Rho GTPase 信号传导促进自噬
DOI：
10.1016/j.molp.2021.03.021
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发表时间：
2021-06-07
期刊：
影响因子：
27.5
通讯作者：
Jiang, Liwen
中科院分区：
文献类型：
--
作者：
Lin, Youshun;Zeng, Yonglun;Jiang, Liwen
Rho家族鸟苷三磷酸酶（GTPases）在植物生长发育调控中的作用已被充分研究。然而，ROP信号通路在调节植物自噬和自噬体形成中的作用知之甚少。在这项研究中，我们确定了一个独特的ROP信号转导机制，介导的模式植物拟南芥在胁迫条件下的发育自噬过渡。ROP 8的功能丧失突变体表现出应激诱导的超敏表型和受损的自噬通量。与ROP/RAC家族中的其他ROP类似，ROP 8表现出质膜和细胞溶质点状定位模式。自噬诱导后，活性ROP 8斑点与自噬体标记物共定位，并在空泡内降解。在人类细胞中，RalB（RAS亚家族GT3）接合其效应子Exo 84用于自噬体组装。然而，RalB对应物在植物谱系中缺失。有趣的是，我们发现植物ROP 8通过其下游效应子Sec 5促进自噬。活细胞超分辨率成像显示ROP 8和Sec 5驻留在吞噬细胞上用于自噬体形成。总之，我们的研究结果突出了ROP 8-Sec 5信号轴在自噬促进中的先前未被重视的作用，为植物如何利用多功能ROP信号网络来协调发育和自噬反应提供了新的见解。
The roles of Rho family guanosine triphosphatases (GTPases) of plants (ROPs) in modulating plant growth and development have been well characterized. However, little is known about the roles of ROP signaling pathways in regulating plant autophagy and autophagosome formation. In this study, we identify a unique ROP signaling mechanism, which mediates developmental to autophagic transition under stress conditions in the model plant Arabidopsis. Loss-of-function mutants of ROP8 showed stress-induced hypersensitive phenotypes and compromised autophagic flux. Similar to other ROPs in the ROP/RAC family, ROP8 exhibits both plasma membrane and cytosolic punctate localization patterns. Upon autophagic induction, active ROP8 puncta colocalize with autophagosomal markers and are degraded inside the vacuole. In human cells, RalB, an RAS subfamily GTPase, engages its effector Exo84 for autophagosome assembly. However, a RalB counterpart is missing in the plant lineage. Intriguingly, we discovered that plant ROP8 promotes autophagy via its downstream effector Sec5. Live-cell super-resolution imaging showed that ROP8 and Sec5 reside on phagophores for autophagosome formation. Taken together, our findings highlight a previously unappreciated role of an ROP8-Sec5 signaling axis in autophagy promotion, providing new insights into how plants utilize versatile ROP signaling networks to coordinate developmental and autophagic responses depending on environmental changes.