Stem cell factor-induced signal transduction in rat mast cells. Activation of phospholipase D but not phosphoinositide-specific phospholipase C in c-kit receptor stimulation.

Stem cell factor (SCF), a hematopoietic growth factor for primitive hematopoietic stem cells, is also known as mast cell growth factor. SCF induced serotonin release from rat peritoneal mast cells, connective tissue-type mast cells. The treatment of rat peritoneal mast cells with SCF failed to produce inositol 1,4,5-trisphosphate, indicating the absence of involvement of phosphoinositide-specific phospholipase C pathway. 1,2-Diacylglycerol (1,2-DG) and phosphatidic acid, however, were increased after stimulation by SCF. Phosphatidylethanol formation catalyzed by phospholipase D (PLD) was observed, together with the release of choline but not phosphocholine. Propranolol, an inhibitor of phosphatidate phosphohydrolase, blocked the production of 1,2-DG. These results indicate that the phosphatidylcholine-specific PLD pathway is the main pathway for the production of 1,2-DG in SCF-stimulated rat peritoneal mast cells. Furthermore, treatment of cells with protein tyrosine kinase inhibitor, genistein, inhibited 1,2-DG formation and serotonin release dose-dependently. Taken together, SCF induces the activation of PLD through the protein tyrosine kinase pathway without activation of phosphoinositide-specific phospholipase C.