title: Altered activation of phospholipase D by lysophosphatidic acid and endothelin-1 in mouse embryo fibroblasts lacking phospholipase C-gamma1.
abstract: Lysophosphatidic acid (LPA) and endothelin-1 (ET-1) activate phospholipase D (PLD) in many cell types. To see if phospholipase C-gamma1 plays a role, we used embryonic fibroblasts from mice in which the PLCgamma1 gene was disrupted. Surprisingly, the effect of LPA on inositol phosphate accumulation was increased in these PLCgamma1-/- cells, whereas that of ET-1 was completely abrogated. When PLD activity was measured, the response to LPA was also enhanced and the response to ET-1 lost in the PLCgamma1-/- cells. Treatment of these cells with ionomycin and oleoyl acetyl glycerol to mimic PLC stimulation restored PLD activity. Treatment of either PLCgamma1+/+ and PLCgamma1-/- cells with tyrosine kinase inhibitors did not inhibit LPA- or ET-1-induced PLD activity. Moreover, LPA and ET-1 treatment of PLCgamma1+/+ and PLCgamma1-/- cells did not cause tyrosine phosphorylation of PLC-gamma1 or PLC-gamma2. In summary, these results show that the altered PLD responses to LPA and ET-1 in PLCgamma1-/- are due to changes in PLC activity and do not involve tyrosine kinase activity.
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Hess
authors.forename: F G
authors.initials: FG
authors.lastname: Buchanan
authors.forename: S
authors.initials: S
authors.lastname: Ryder
authors.forename: J H
authors.initials: JH
authors.lastname: Exton
mesh_terms: D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation; D005347:Fibroblasts / Q000201:enzymology*; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology*; D051379:Mice; D051966:Phospholipase C gamma; D010739:Phospholipase D / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D010738:Type C Phospholipases / Q000235:genetics* / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D008246:Lysophospholipids; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D010739:Phospholipase D