title: Aluminum inhibits phosphatidic acid formation by blocking the phospholipase C pathway.
abstract: Aluminum (Al(3+)) has been recognized as a main toxic factor in crop production in acid lands. Phosphatidic acid (PA) is emerging as an important lipid signaling molecule and has been implicated in various stress-signaling pathways in plants. In this paper, we focus on how PA generation is affected by Al(3+) using Coffea arabica suspension cells. We pre-labeled cells with [(32)P]orthophosphate ((32)Pi) and assayed for (32)P-PA formation in response to Al(3+). Treating cells for 15 min with either AlCl(3) or Al(NO(3))(3) inhibited the formation of PA. In order to test how Al(3+) affected PA signaling, we used the peptide mastoparan-7 (mas-7), which is known as a very potent stimulator of PA formation. The Al(3+) inhibited mas-7 induction of PA response, both before and after Al(3+) incubation. The PA involved in signaling is generated by two distinct phospholipid signaling pathways, via phospholipase D (PLD; EC: 3.1.4.4) or via Phospholipase C (PLC; EC: 3.1.4.3), and diacylglycerol kinase (DGK; EC 2.7.1.107). By labeling with (32)Pi for short periods of time, we found that PA formation was inhibited almost 30% when the cells were incubated with AlCl(3) suggesting the involvement of the PLC/DGK pathway. Incubation of cells with PLC inhibitor, U73122, affected PA formation, like AlCl(3) did. PLD in vivo activation by mas-7 was reduced by Al(3+). These results suggest that PA formation was prevented through the inhibition of the PLC activity, and it provides the first evidence for the role of Al toxicity on PA production.
authors.affiliation: Centro de Investigación Científica de Yucatán, Unidad de Bioquímica y Biología Molecular de Plantas, Calle 43, 130 Col Chuburná de Hidalgo, Mérida Yucatán, México.
authors.forename: Ana
authors.initials: A
authors.lastname: Ramos-Díaz
authors.forename: Ligia
authors.initials: L
authors.lastname: Brito-Argáez
authors.forename: Teun
authors.initials: T
authors.lastname: Munnik
authors.forename: S M Teresa
authors.initials: SM
authors.lastname: Hernández-Sotomayor
mesh_terms: D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000494:pharmacology; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D040503:Coffea / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D019852:Diacylglycerol Kinase / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides / Q000494:pharmacology; D010712:Phosphatidic Acids / Q000096:biosynthesis*; D010739:Phospholipase D / Q000378:metabolism; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism*; D014862:Wasp Venoms / Q000494:pharmacology
chemical_list: D017607:Aluminum Compounds; D002712:Chlorides; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010712:Phosphatidic Acids; D014862:Wasp Venoms; D000077410:Aluminum Chloride; C037500:mastoparan; D019852:Diacylglycerol Kinase; D010738:Type C Phospholipases; D010739:Phospholipase D