Metacaspase-8 modulates programmed cell death induced by ultraviolet light and H2O2 in Arabidopsis
Metacaspase-8 modulates programmed cell death induced by ultraviolet light and H2O2 in Arabidopsis
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DOI：
10.1074/jbc.m704185200
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发表时间：
2008-01-11
影响因子：
4.8
通讯作者：
Gallois, Patrick
中科院分区：
文献类型：
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作者：
He, Rui;Drury, Georgina E.;Gallois, Patrick
程序性细胞死亡（PCD）是一种遗传控制的细胞死亡，在发育过程中受到调节，并在环境胁迫或病原体感染时被激活。PCD跨界和门的保守程度尚不清楚;然而，尽管半胱天冬酶是作为动物细胞凋亡的关键组分的蛋白酶，但植物的基因组中没有正链半胱天冬酶序列。植物和真菌中与动物半胱天冬酶关系最密切的蛋白酶的发现导致了这样的假设，即在这些生物体中，后半胱天冬酶是动物半胱天冬酶的功能同源物。拟南芥有9个metacaspase基因，到目前为止，它是未知的家族成员，如果有的话，参与PCD的调控。我们在这里表明，metacaspase-8（AtMC 8）是一个成员的基因家族强烈上调由UVC，H2 O2，或甲基紫精引起的氧化应激。这种上调依赖于RCD 1，氧化应激反应的介质。重组metacaspase-8精氨酸后裂解，具有pH值为8的最佳值，并补充了酵母metacaspase敲除的H2 O2无死亡表型。过表达AtMC 8可上调UVC和H2 O2诱导的细胞死亡，而敲除AtMC 8可降低UVC和H2 O2诱导的细胞死亡。基因敲除的种子和幼苗对除草剂甲基紫精的耐受性增加。我们认为metacaspase-8是氧化应激激活的进化保守PCD途径的一部分。
Programmed cell death (PCD) is a genetically controlled cell death that is regulated during development and activated in response to environmental stresses or pathogen infection. The degree of conservation of PCD across kingdoms and phylum is not yet clear; however, whereas caspases are proteases that act as key components of animal apoptosis, plants have no orthologous caspase sequences in their genomes. The discovery of plant and fungi metacaspases as proteases most closely related to animal caspases led to the hypothesis that metacaspases are the functional homologues of animal caspases in these organisms. Arabidopsis thaliana has nine metacaspase genes, and so far it is unknown which members of the family if any are involved in the regulation of PCD. We show here that metacaspase-8 (AtMC8) is a member of the gene family strongly up-regulated by oxidative stresses caused by UVC, H2O2, or methyl viologen. This up-regulation was dependent of RCD1, a mediator of the oxidative stress response. Recombinant metacaspase-8 cleaved after arginine, had a pH optimum of 8, and complemented the H2O2 no-death phenotype of a yeast metacaspase knock-out. Overexpressing AtMC8 up-regulated PCD induced by UVC or H2O2, and knocking out AtMC8 reduced cell death triggered by UVC and H2O2 in protoplasts. Knock-out seeds and seedlings had an increased tolerance to the herbicide methyl viologen. We suggest that metacaspase-8 is part of an evolutionary conserved PCD pathway activated by oxidative stress.