Protein tyrosine dephosphorylation during copper-induced cell death in rice roots.
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.
Hung
Wan-Chi
WC
Department of Life Sciences, National Cheng Kung University, No. 1 University Road, 701 Tainan, Taiwan.
Huang
Dinq-Ding
DD
Chien
Pei-Shan
PS
Yeh
Chuan-Ming
CM
Chen
Po-Yu
PY
Chi
Wen-Chang
WC
Huang
Hao-Jen
HJ
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
D018744:DNA, Plant; D010940:Plant Proteins; D014638:Vanadates; D014443:Tyrosine; D003300:Copper; D017027:Protein Tyrosine Phosphatases