Bax-induced cell death of Arabidopsis is meditated through reactive oxygen-dependent and -independent processes
Bax-induced cell death of Arabidopsis is meditated through reactive oxygen-dependent and -independent processes
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DOI：
10.1007/s11103-004-3096-4
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发表时间：
2004-09-01
影响因子：
5.1
通讯作者：
Yun, DJ
中科院分区：
文献类型：
--
作者：
Baek, D;Nam, J;Yun, DJ
拟南芥原生质体系统的发展解剖植物细胞死亡在个别细胞。Bax是Bcl-2家族的哺乳动物促凋亡成员，在拟南芥中诱导类凋亡细胞死亡。通过糖皮质激素诱导型启动子表达小鼠Bax cDNA的拟南芥叶肉原生质体中Bax的积累导致细胞凋亡的细胞学特征，即DNA片段化、空泡化增加和质膜完整性丧失。使用水母绿色荧光蛋白（GFP）报告基因监测的体内靶向分析表明，全长Bax定位于线粒体，就像在动物细胞中一样。Bax的羧基末端跨膜结构域的缺失完全取消了对线粒体的靶向。Bax的表达后，活性氧（ROS）的积累。在诱导Bax表达过程中，用抗氧化剂N-乙酰-L-半胱氨酸（NAC）处理原生质体强烈抑制了Bax介导的ROS产生和细胞死亡表型。然而，一些群体的ROS耗尽的细胞仍然诱导细胞死亡，表明有一个过程，即ROS介导的植物细胞死亡是独立的ROS积累。因此，对由植物细胞死亡介导的植物细胞死亡的抑制也发生在两个不同的过程中。过表达一个关键的氧化还原调节剂，拟南芥核苷二磷酸激酶2（AtNDPK 2）下调ROS的积累和抑制ROS介导的细胞死亡和拟南芥Bax抑制剂-1（AtBI-1）的瞬时表达基本上抑制ROS诱导的细胞死亡，而不改变细胞的ROS水平。两者合计，我们的研究结果共同表明，ROS介导的细胞死亡及其抑制在植物中是由ROS依赖性和非依赖性的过程。
An Arabidopsis protoplast system was developed for dissecting plant cell death in individual cells. Bax, a mammalian pro-apoptotic member of the Bcl-2 family, induces apoptotic-like cell death in Arabidopsis. Bax accumulation in Arabidopsis mesophyll protoplasts expressing murine Bax cDNA from a glucocorticoid-inducible promoter results in cytological characteristics of apoptosis, namely DNA fragmentation, increased vacuolation, and loss of plasma membrane integrity. In vivo targeting analysis monitored using jellyfish green fluorescent protein (GFP) reporter indicated full-length Bax was localized to the mitochondria, as it does in animal cells. Deletion of the carboxyl-terminal transmembrane domain of Bax completely abolished targeting to mitochondria. Bax expression was followed by reactive oxygen species (ROS) accumulation. Treatment of protoplasts with the antioxidant N-acetyl-L-cysteine (NAC) during induction of Bax expression strongly suppressed Bax-mediated ROS production and the cell death phenotype. However, some population of the ROS depleted cells still induced cell death, indicating that there is a process that Bax-mediated plant cell death is independent of ROS accumulation. Accordingly, suppression of Bax-mediated plant cell death also takes place in two different processes. Over-expression of a key redox-regulator, Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) down-regulated ROS accumulation and suppressed Bax-mediated cell death and transient expression of Arabidopsis Bax inhibitor-1 (AtBI-1) substantially suppressed Bax-induced cell death without altering cellular ROS level. Taken together, our results collectively suggest that the Bax-mediated cell death and its suppression in plants is mediated by ROS-dependent and -independent processes.