Background

Vacuolar processing enzymes (VPEs) have been identified as the enzymes that regulate vacuole-mediated programmed cell death (PCD) in plants. The mechanism that VPE regulates the PCD in rice aleurone layers remains unknown.

Results

The aleurone layers treated with distilled water exerted caspase-1 and VPE activity, both of which were inhibited by the caspase-1 specific inhibitor Ac-YVAD-CMK but not by the caspase-3 specific inhibitor Ac-DEVD-CHO. However, the caspase-1 and caspase-3 inhibitors weakened the activity of caspase-3. Combined with the effects of endogenous gibberellin (GA) on the induction of OsVPEs, we suggest that the OsVPE3 in the aleurone layers, which exhibits caspase-1-like activity, is a key molecule in GA-induced PCD via regulating the protease with caspase-3-like activity. Many studies have confirmed that vacuolar fusion is an important feature of vacuole-mediated PCD in plants. In this experiment, the process of vacuole fusion was accompanied by changes in the structure of actin filaments (AFs), specifically, their depolymerization and polymerization. The process of vacuolar fusion was accelerated or delayed by the promotion or inhibition of the depolymerization of AFs, respectively. Here, the inhibition of OsVPE3 blocked the depolymerization of AFs and delayed the fusion of vacuoles, indicating that OsVPE3 can regulate the fusion of vacuoles in rice aleurone layers via mediating AFs. Furthermore, the depolymerization of AFs contributed to the up-regulation of OsVPE3 gene expression and VPE activity, resulting in accelerated PCD in rice aleurone layers. However, the inhibitor of VPE reversed the effects of AF depolymerization on the activity of VPE, then postponing the process of PCD, implying that AF can involve in GA-induced PCD of rice aleurone layers by mediating OsVPE3.

Conclusions

Together, activation of OsVPE3 and depolymerization of AFs shortened the process of vacuolation and PCD in rice aleurone layers, and OsVPE3 interacted with AFs during regulation.

中文翻译：

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OsVPE3通过与肌动蛋白微丝的相互作用介导GA诱导的水稻Aleurone层中的程序性细胞死亡。

背景

液泡加工酶（VPE）已被鉴定为调节植物液泡介导的程序性细胞死亡（PCD）的酶。VPE调节水稻糊粉层中PCD的机制仍然未知。

结果

用蒸馏水处理的糊粉层具有caspase-1和VPE活性，两者均受caspase-1特异性抑制剂Ac-YVAD-CMK抑制，但不受caspase-3特异性抑制剂Ac-DEVD-CHO抑制。但是，caspase-1和caspase-3抑制剂减弱了caspase-3的活性。结合内源赤霉素（GA）诱导OsVPEs的影响，我们表明糊粉层中的OsVPE3具有caspase-1样活性，是通过用caspase调节蛋白酶在GA诱导的PCD中的关键分子像-3-的活动。许多研究已经证实，液泡融合是液泡介导的PCD在植物中的重要特征。在该实验中，液泡融合过程伴随着肌动蛋白丝（AFs）结构的变化，特别是它们的解聚和聚合。液泡融合过程分别通过促进或抑制AF的解聚而加速或延迟。在这里，OsVPE3的抑制作用阻止了AF的解聚并延迟了液泡的融合，这表明OsVPE3可以通过介导的AF调节水稻糊粉层中液泡的融合。此外，AF的解聚作用还促进了AF的上调。OsVPE3基因表达和VPE活性，导致水稻糊粉层中PCD加速。然而，VPE的抑制剂逆转了AF解聚对VPE活性的影响，然后推迟了PCD的过程，这暗示AF可以通过介导OsVPE3参与GA诱导的水稻糊粉层的PCD。

结论

一起，OsVPE3的活化和AF的解聚缩短了水稻糊粉层的空泡化和PCD的过程，并且OsVPE3在调节过程中与AF相互作用。