Involvement of phosphatidylinositol 3'-kinase in stem-cell-factor-induced phospholipase D activation and arachidonic acid release

Eur J Biochem. 1997 Aug 15;248(1):149-55. doi: 10.1111/j.1432-1033.1997.00149.x.

Abstract

We have shown previously that the stem cell factor (SCF) receptor undergoes phosphorylation on serine residues following ligand stimulation, and that this phopshorylation is dependent mainly on the activity of protein kinase C (PKC). In the present study, we have further investigated the molecular mechanisms behind SCF-stimulated activation of PKC, and found that SCF does not activate phosphatidylinositol-specific phospholipase C. In contrast, phospholipase D (PLD) is activated in response to SCF in a dose-dependent manner. Activation of PLD was not inhibited by calphostin C, an inhibitor of PKC. On the other hand, inhibitors of phosphatidylinositol PtdIns 3'-kinase (PtdIns 3'-kinase), i.e. wortmannin and LY294002, inhibited SCF-induced PLD activation. Moreover, a mutant SCF receptor in which Tyr721, which is responsible for activation of PtdIns 3'-kinase, is mutated to a phenylalanine residue was unable to mediate activation of PLD. Thus, PtdIns 3'-kinase appears to be essential for SCF-induced PLD activation. Furthermore, we demonstrate that phosphatidic acid (PtdH), generated through the action of PLD in response to SCF, is metabolized to diacylglycerol by dephosphorylation. Diacylglycerol can then activate PKC, and, moreover, after deacylation by a diacylglycerol lipase, yield arachidonic acid, an important second messenger in cell signaling.

MeSH terms

  • Arachidonic Acid / metabolism*
  • Base Sequence
  • Cell Line
  • DNA, Complementary / genetics
  • Diglycerides / biosynthesis
  • Enzyme Activation / drug effects
  • Humans
  • Models, Biological
  • Mutagenesis, Site-Directed
  • Phosphatidylinositol 3-Kinases
  • Phosphatidylinositol Diacylglycerol-Lyase
  • Phosphoinositide Phospholipase C
  • Phospholipase D / metabolism*
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Propranolol / pharmacology
  • Proto-Oncogene Proteins c-kit / genetics
  • Proto-Oncogene Proteins c-kit / metabolism
  • Second Messenger Systems
  • Stem Cell Factor / metabolism
  • Stem Cell Factor / pharmacology*
  • Transfection
  • Type C Phospholipases / metabolism

Substances

  • DNA, Complementary
  • Diglycerides
  • Stem Cell Factor
  • Arachidonic Acid
  • Propranolol
  • Phosphatidylinositol 3-Kinases
  • Phosphotransferases (Alcohol Group Acceptor)
  • Proto-Oncogene Proteins c-kit
  • Type C Phospholipases
  • Phosphoinositide Phospholipase C
  • Phospholipase D
  • Phosphatidylinositol Diacylglycerol-Lyase