α-Tomatine, the major saponin in tomato, induces programmed cell death mediated by reactive oxygen species in the fungal pathogen Fusarium oxysporum

The tomato saponin α-tomatine has been proposed to kill sensitive cells by binding to cell membranes followed by leakage of cell components. However, details of the modes of action of the compound on fungal cells are poorly understood. In the present study, mechanisms involved in α-tomatine-induced...

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Bibliographic Details
Published in:FEBS letters 2007-07, Vol.581 (17), p.3217-3222
Main Authors: Ito, Shin-ichi, Ihara, Takashi, Tamura, Hideyuki, Tanaka, Shuhei, Ikeda, Tsuyoshi, Kajihara, Hiroshi, Dissanayake, Chandrika, Abdel-Motaal, Fatma F., El-Sayed, Magdi A.
Format: Article
Language:English
Subjects:
Antifungal Agents - pharmacology
Apoptosis
Apoptosis - drug effects
Calcium Signaling - drug effects
Cell Death - drug effects
Enzyme Activation - drug effects
Fusarium - drug effects
Fusarium - metabolism
Fusarium oxysporum
Glycoalkaloid
GTP-Binding Proteins - metabolism
Lycopersicon esculentum
Lycopersicon esculentum - chemistry
Protein-Tyrosine Kinases - metabolism
Reactive Oxygen Species - metabolism
Reactive Oxygen Species - pharmacology
Saponins - chemistry
Saponins - pharmacology
Signal Transduction - drug effects
Tomatine - analogs & derivatives
Tomatine - pharmacology
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Summary:The tomato saponin α-tomatine has been proposed to kill sensitive cells by binding to cell membranes followed by leakage of cell components. However, details of the modes of action of the compound on fungal cells are poorly understood. In the present study, mechanisms involved in α-tomatine-induced cell death of fungi were examined using a filamentous pathogenic fungus Fusarium oxysporum. α-Tomatine-induced cell death of F. oxysporum (TICDF) occurred only under aerobic conditions and was blocked by the mitochondrial F 0F 1-ATPase inhibitor oligomycin, the caspase inhibitor D-VAD-fmk, and protein synthesis inhibitor cycloheximide. Fungal cells exposed to α-tomatine showed TUNEL-positive nuclei, depolarization of transmembrane potential of mitochondria, and reactive oxygen species (ROS) accumulation. These results suggest that TICDF occurs through a programmed cell death process in which mitochondria play a pivotal role. Pharmacological studies using inhibitors suggest that α-tomatine activates phosphotyrosine kinase and monomeric G-protein signaling pathways leading to Ca 2+ elevation and ROS burst in F. oxysporum cells.
ISSN:0014-5793
1873-3468
DOI:10.1016/j.febslet.2007.06.010