Phospholipase C signaling involvement in macrotubule assembly and activation of the mechanism regulating protoplast volume in plasmolyzed root cells of Triticum turgidum.
The role of phosphoinositide-specific phospholipase C (PI-PLC) signaling in the macrotubule-dependent protoplast volume regulation in plasmolyzed root cells of Triticum turgidum was investigated. At the onset of hyperosmotic stress, PI-PLC activation was documented. Inhibition of PI-PLC activity by U73122 blocked tubulin macrotubule formation in plasmolyzed cells and their protoplast volume regulatory mechanism. In neomycin-treated plasmolyzed cells, macrotubule formation and protoplast volume regulation were not affected. In these cells the PI-PLC pathway is down-regulated as neomycin sequesters the PI-PLC substrate, 4,5-diphosphate-phosphatidyl inositol (PtdInsP(2)). These phenomena were unaffected by R59022, an inhibitor of phosphatidic acic (PA) production via the PLC pathway. Taxol, a microtubule (MT) stabilizer, inhibited the hyperosmotic activation of PI-PLC, but oryzalin, which disorganized MTs, triggered PI-PLC activity. Taxol prevented macrotubule formation and inhibited the mechanism regulating the volume of the plasmolyzed protoplast. Neomycin partly relieved some of the taxol effects. These data suggest that PtdInspP(2) turnover via PI-PLC assists macrotubule formation and activation of the mechanism regulating the plasmolyzed protoplast volume; and the massive disorganization of MTs that is carried out at the onset of hyperosmotic treatment triggers the activation of this mechanism.
Komis
George
G
Department of Botany, Faculty of Biology, University of Athens, Athens 15784, Greece.
Galatis
Basil
B
Department of Botany, Faculty of Biology, University of Athens, Athens 15784, Greece.
Quader
Hartmut
H
Biocenter Klein Flottbek, University of Hamburg, D-22609 Hamburg, Germany.
Galanopoulou
Dia
D
Laboratory of Biochemistry, Faculty of Chemistry, University of Athens, Athens, 157 71, Greece.
Apostolakos
Panagiotis
P
Department of Botany, Faculty of Biology, University of Athens, Athens 15784, Greece.
D019852:Diacylglycerol Kinase / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D004963:Estrenes / Q000494:pharmacology; D008353:Mannitol / Q000494:pharmacology; D008870:Microtubules / Q000502:physiology; D009355:Neomycin / Q000494:pharmacology; D017239:Paclitaxel / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D011523:Protoplasts / Q000378:metabolism*; D011744:Pyrimidinones / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014908:Triticum / Q000378:metabolism*
D004963:Estrenes; D011744:Pyrimidinones; D011760:Pyrrolidinones; D013844:Thiazoles; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D008353:Mannitol; C047505:R 59022; D019852:Diacylglycerol Kinase; D054801:Phosphoinositide Phospholipase C; D009355:Neomycin; D017239:Paclitaxel