title: Involvement of ethylene and lipid signalling in cadmium-induced programmed cell death in tomato suspension cells.
abstract: Cadmium-induced cell death was studied in suspension-cultured tomato (Lycopersicon esculentum Mill.) cells (line MsK8) treated with CdSO(4). Within 24 h, cadmium treatment induced cell death in a concentration-dependent manner. Cell cultures showed recovery after 2-3 days which indicates the existence of an adaptation mechanism. Cadmium-induced cell death was alleviated by the addition of sub muM concentrations of peptide inhibitors specific to human caspases indicating that cell death proceeds through a mechanism with similarities to animal programmed cell death (PCD, apoptosis). Cadmium-induced cell death was accompanied by an increased production of hydrogen peroxide (H(2)O(2)) and simultaneous addition of antioxidants greatly reduced cell death. Inhibitors of phospholipase C (PLC) and phospholipase D (PLD) signalling pathway intermediates reduced cadmium-induced cell death. Treatment with the G-protein activator mastoparan and a cell permeable analogue of the lipid signal second messenger phosphatidic acid (PA) induced cell death. Ethylene, while not inducing cell death when applied alone, stimulated cadmium-induced cell death. Application of the ethylene biosynthesis inhibitor aminoethoxy vinylglycine (AVG) reduced cadmium-induced cell death, and this effect was alleviated by simultaneous treatment with ethylene. Together the results show that cadmium induces PCD exhibiting apoptotic-like features. The cell death process requires increased H(2)O(2) production and activation of PLC, PLD and ethylene signalling pathways.
authors.affiliation: Regional Research Centre and Extension Service of Floriculture and Agriculture (RCNPO), 1222 Negovan, Sofia, Bulgaria.
authors.forename: E T
authors.initials: ET
authors.lastname: Yakimova
authors.forename: V M
authors.initials: VM
authors.lastname: Kapchina-Toteva
authors.forename: L-J
authors.initials: LJ
authors.lastname: Laarhoven
authors.forename: F M
authors.initials: FM
authors.lastname: Harren
authors.forename: E J
authors.initials: EJ
authors.lastname: Woltering
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D019187:Cadmium Compounds / Q000494:pharmacology*; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D005030:Ethylenes / Q000378:metabolism*; D050356:Lipid Metabolism / Q000187:drug effects*; D018551:Solanum lycopersicum / Q000166:cytology*; D016897:Respiratory Burst / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D013431:Sulfates / Q000494:pharmacology*
chemical_list: D019187:Cadmium Compounds; D061945:Caspase Inhibitors; D005030:Ethylenes; D013431:Sulfates; C036216:ethylene; C037123:cadmium sulfate