Protein tyrosine dephosphorylation during copper-induced cell death in rice roots

• Published in: Chemosphere (Oxford) Vol. 69; no. 1; pp. 55 - 62
• Main Authors: Hung, Wan-Chi, Huang, Dinq-Ding, Chien, Pei-Shan, Yeh, Chuan-Ming, Chen, Po-Yu, Chi, Wen-Chang, Huang, Hao-Jen
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-2007; Elsevier
• Subjects: Animal, plant and microbial ecology; apoptosis; Applied ecology; Biological and medical sciences; Cell Death - drug effects; Copper - toxicity; dephosphorylation; DNA Fragmentation; DNA, Plant - analysis; Ecotoxicology, biological effects of pollution; Fundamental and applied biological sciences. Psychology; General aspects; Oryza - drug effects; Oryza - physiology; Oryza sativa; phosphoproteins; Phosphorylation - drug effects; phytotoxicity; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - physiology; Programmed cell death; Protein Tyrosine Phosphatases - antagonists & inhibitors; rice; roots; signal transduction; Signalling; tyrosine; Tyrosine - metabolism; Tyrosine phosphorylation; Vanadates - pharmacology; PCD; Tyrosine phosphorylation; ROS; Programmed cell death; Signalling; GSH; EGTA; Monocotyledones; Phosphorylation; Protein; Heavy metal; Oryza; Gramineae; Cell death; Angiospermae; Spermatophyta; Copper
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.04.073

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
3VO
4). Treatment of rice roots with Na
3VO
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.