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

Kozawa, Osamu; Blume-Jensen, Peter; Heldin, Carl-Henrik and Rönnstrand, Lars LU (1997) In European Journal of Biochemistry 248(1). p.149-155
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... (More)
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. (Less)
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@article{06fc0d60-e8bb-4b48-afea-27c32c777809,
  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.},
  author       = {Kozawa, Osamu and Blume-Jensen, Peter and Heldin, Carl-Henrik and Rönnstrand, Lars},
  issn         = {0014-2956},
  keyword      = {Complementary/genetics
Diglycerides/biosynthesis
Enzyme Activation/drug effects
Humans
Models,Arachidonic Acid/*metabolism
Base Sequence
Cell Line
DNA,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/metabolism
Second Messenger Systems
Stem Cell Factor/metabolism/*pharmacology
Transfection
Type C Phospholipases/metabolism},
  language     = {eng},
  number       = {1},
  pages        = {149--155},
  publisher    = {Wiley-Blackwell},
  series       = {European Journal of Biochemistry},
  title        = {Involvement of phosphatidylinositol 3'-kinase in stem-cell-factor-induced phospholipase D activation and arachidonic acid release},
  url          = {http://dx.doi.org/10.1111/j.1432-1033},
  volume       = {248},
  year         = {1997},
}