title: Bcl-2 suppresses hydrogen peroxide-induced programmed cell death via OsVPE2 and OsVPE3, but not via OsVPE1 and OsVPE4, in rice.
abstract: 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.
authors.affiliation: 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.
authors.forename: Minjuan
authors.initials: M
authors.lastname: Deng
authors.forename: Hongwu
authors.initials: H
authors.lastname: Bian
authors.forename: Yakun
authors.initials: Y
authors.lastname: Xie
authors.forename: Yongho
authors.initials: Y
authors.lastname: Kim
authors.forename: Wenzhe
authors.initials: W
authors.lastname: Wang
authors.forename: Erpei
authors.initials: E
authors.lastname: Lin
authors.forename: Zhanghui
authors.initials: Z
authors.lastname: Zeng
authors.forename: Fu
authors.initials: F
authors.lastname: Guo
authors.forename: Jianwei
authors.initials: J
authors.lastname: Pan
authors.forename: Ning
authors.initials: N
authors.lastname: Han
authors.forename: Junhui
authors.initials: J
authors.lastname: Wang
authors.forename: Qian
authors.initials: Q
authors.lastname: Qian
authors.forename: Muyuan
authors.initials: M
authors.lastname: Zhu
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D016415:Sequence Alignment; D015533:Transcriptional Activation / Q000187:drug effects; D014617:Vacuoles / Q000187:drug effects / Q000502:physiology
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D003546:Cysteine Endopeptidases; C089278:vacuolar processing enzyme