title: Nitric oxide promotes MPK6-mediated caspase-3-like activation in cadmium-induced Arabidopsis thaliana programmed cell death.
abstract: Nitric oxide (NO), a vital cell-signalling molecule, has been reported to regulate toxic metal responses in plants. This work investigated the effects of NO and the relationship between NO and mitogen-activated protein kinase (MAPK) in Arabidopsis (Arabidopsis thaliana) programmed cell death (PCD) induced by cadmium (Cd(2+) ) exposure. With fluorescence resonance energy transfer (FRET) analysis, caspase-3-like protease activation was detected after Cd(2+)  treatment. This was further confirmed with a caspase-3 substrate assay. Cd(2+) -induced caspase-3-like activity was inhibited in the presence of the NO-specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), suggesting that NO mediated caspase-3-like protease activation under Cd(2+)  stress conditions. Pretreatment with cPTIO effectively inhibited Cd(2+) -induced MAPK activation, indicating that NO also affected the MAPK pathway. Interestingly, Cd(2+) -induced caspase-3-like activity was significantly suppressed in the mpk6 mutant, suggesting that MPK6 was required for caspase-3-like protease activation. To our knowledge, this is the first demonstration that NO promotes Cd(2+) -induced Arabidopsis PCD by promoting MPK6-mediated caspase-3-like activation.
authors.affiliation: MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ye
authors.forename: Zhe
authors.initials: Z
authors.lastname: Li
authors.forename: Da
authors.initials: D
authors.lastname: Xing
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death; D004789:Enzyme Activation; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; D002104:Cadmium; D009569:Nitric Oxide; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D053148:Caspase 3