title: Protein tyrosine dephosphorylation during copper-induced cell death in rice roots.
abstract: Early signalling events that control the process of heavy metal-induced cell death are largely unknown in plants. In mammals protein tyrosine phosphorylation plays an important role in the activation of programmed cell death. We thus examined the involvement of tyrosine phosphorylation in Cu-induced rice cell death. This investigation demonstrates that Cu induces cell death and DNA fragmentation in rice root cells. In the presence of Cu, the level of phosphotyrosine accumulation declined in the band of 45 kDa, p45. To analyze the role of tyrosine dephosphorylation for the regulation of Cu-induced cell death more precisely, we increased levels of tyrosine phosphorylation using the protein tyrosine phosphatase inhibitor, sodium orthovanadate (Na(3)VO(4)). Treatment of rice roots with Na(3)VO(4) blocked Cu-induced cell death and protein tyrosine dephosphorylation. In addition, the antioxidant GSH and the calcium chelator EGTA significantly abolished Cu-induced cell death and protein tyrosine dephosphorylation. These results provide evidence that dephosphorylation of a tyrosine-phosphorylated protein, p45, is an important step in the Cu-triggered signalling transduction pathway.
authors.affiliation: Department of Life Sciences, National Cheng Kung University, No. 1 University Road, 701 Tainan, Taiwan.
authors.forename: Wan-Chi
authors.initials: WC
authors.lastname: Hung
authors.forename: Dinq-Ding
authors.initials: DD
authors.lastname: Huang
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Chien
authors.forename: Chuan-Ming
authors.initials: CM
authors.lastname: Yeh
authors.forename: Po-Yu
authors.initials: PY
authors.lastname: Chen
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chi
authors.forename: Hao-Jen
authors.initials: HJ
authors.lastname: Huang
mesh_terms: D016923:Cell Death / Q000187:drug effects; D003300:Copper / Q000633:toxicity*; D053938:DNA Fragmentation; D018744:DNA, Plant / Q000032:analysis; D012275:Oryza / Q000187:drug effects* / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000502:physiology; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D014443:Tyrosine / Q000378:metabolism*; D014638:Vanadates / Q000494:pharmacology
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D014638:Vanadates; D014443:Tyrosine; D003300:Copper; D017027:Protein Tyrosine Phosphatases