State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory for Cell and Gene Engineering of Zhejiang province, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
FEBS J. 2011 Dec;278(24):4797-810. doi: 10.1111/j.1742-4658.2011.08380.x. Epub 2011 Oct 28.
Hydrogen peroxide (H(2)O(2)) is known to be a key player in apoptosis in animals. The components and pathways regulating H(2)O(2)-induced programmed cell death in plants, however, remain largely unknown. In the present study, rice transgenic lines overexpressing Bcl-2, a human apoptotic suppressor, were obtained. These transgenic lines showed increased tolerance to high levels of H(2)O(2), resulting in increased seed germination rates, root elongation, root tip cell viability and chlorophyll retention compared to control lines. In the control lines, treatment with H(2)O(2) resulted in DNA laddering and a clear terminal transferase dUTP nick end labeling signal, which are the hallmarks of programmed cell death. However, this effect was not detected in the Bcl-2-overexpressing transgenic lines. Further investigations indicated that Bcl-2 suppressed H(2)O(2)-induced programmed cell death but did not inhibit stress-elicited reactive oxygen species production in rice. RT-PCR revealed that the expression of the two vacuolar processing enzyme genes (i.e. OsVPE2 and OsVPE3) was dramatically induced by H(2)O(2) in the wild-type line but not in the Bcl-2-overexpressing line. Moreover, treatment with H(2)O(2) resulted in the disruption of the vacuolar membrane in the wild-type line. The expression levels of OsVPE1 and OsVPE4 did not significantly differ between the wild-type line and the transgenic line that was treated or untreated with H(2)O(2). The similar roles of Bcl-2 and OsVPEs during endogenous reactive oxygen species-triggered programmed cell death were also confirmed by NaCl stress in rice. To our knowledge, the present study is the first to demonsatrate that Bcl-2 overexpression inhibits H(2)O(2)-induced programmed cell death and enhances H(2)O(2) tolerance. We propose that Bcl-2 overexpression in rice suppresses the transcriptional activation of OsVPE2 and OsVPE3, but not of OsVPE1 or OsVPE4.
过氧化氢（H2O2）是动物细胞凋亡过程中的关键因子。然而，植物中调节 H2O2 诱导程序性细胞死亡的成分和途径在很大程度上仍不清楚。本研究获得了过表达人凋亡抑制因子 Bcl-2 的水稻转基因株系。这些转基因株系对高浓度 H2O2 的耐受性增强，与对照株系相比，种子发芽率、根伸长、根尖细胞活力和叶绿素保留率均增加。在对照株系中，用 H2O2 处理导致 DNA 梯状条带形成和末端转移酶 dUTP 缺口末端标记信号明显，这是程序性细胞死亡的标志。然而，在过表达 Bcl-2 的转基因株系中未检测到这种效应。进一步的研究表明，Bcl-2 抑制 H2O2 诱导的程序性细胞死亡，但不抑制水稻中应激诱导的活性氧产生。RT-PCR 显示，在野生型株系中，两种液泡加工酶基因（即 OsVPE2 和 OsVPE3）的表达被 H2O2 显著诱导，但在过表达 Bcl-2 的株系中没有。此外，用 H2O2 处理导致野生型株系的液泡膜破裂。在野生型株系和未用 H2O2 处理或处理的转基因株系中，OsVPE1 和 OsVPE4 的表达水平没有显著差异。在水稻中，Bcl-2 和 OsVPEs 在内源活性氧触发的程序性细胞死亡中的相似作用也通过 NaCl 胁迫得到了证实。据我们所知，本研究首次证明 Bcl-2 的过表达抑制 H2O2 诱导的程序性细胞死亡并增强 H2O2 耐受性。我们提出，Bcl-2 在水稻中的过表达抑制 OsVPE2 和 OsVPE3 的转录激活，但不抑制 OsVPE1 或 OsVPE4。
