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Requirement of Syk‐phospholipase C‐γ2 pathway for phorbol ester‐induced phospholipase D activation in DT40 cells
Author(s) -
Hitomi Tomohiro,
Yanagi Shigeru,
Inatome Ryoko,
Ding Junyi,
Takano Tomoko,
Yamamura Hirohei
Publication year - 2001
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2001.00434.x
Subject(s) - syk , bruton's tyrosine kinase , phospholipase d , protein kinase c , autophosphorylation , biology , phorbol , tyrosine kinase , phospholipase c , lyn , signal transduction , biochemistry , diacylglycerol kinase , enzyme activator , microbiology and biotechnology , phosphorylation , protein kinase a
Background Treatment of many cell types with phorbol esters stimulates phospholipase D (PLD) activity implying regulation of the enzyme by protein kinase C. Studies of the effects of several protein‐tyrosine kinase (PTK) inhibitors have suggested that PTK(s) play some roles in the phorbol ester‐induced PLD activation, but it remains unclear how and which PTK(s) is involved in this pathway. In this study, we investigated the roles of Syk and other PTKs for the phorbol esters, 12‐O‐tetradecanoylphorbol 13‐acetate (TPA)‐induced PLD activation in K562 and DT40 cells .Results TPA‐induced PLD activation was remarkably reduced in both Syk dominant negative mutant K562 cells and Syk deficient DT40 B cells. Mutational analysis further indicated that two major autophosphorylation sites (Tyr‐518 and Tyr‐519) of Syk are critical for PLD activation. Similarly, TPA‐induced PLD activation was reduced in Btk deficient cells, but unaffected in Lyn deficient cells. Finally, in cells deficient in the PLC‐γ2, one of the phosphorylated substrates regulated by Syk and Btk, TPA‐induced PLD activation, as well as phosphatidylinositol 4,5‐bisphosphate (PIP 2 ) hydrolysis was remarkably reduced .Conclusions We demonstrated that the Syk, Btk and PLC‐γ2 pathways are required for TPA‐induced PLD activation in DT40 cells .