Overactivation of phospholipase C-gamma1 renders platelet-derived growth factor beta-receptor-expressing cells independent of the phosphatidylinositol 3-kinase pathway for chemotaxis
1999 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 274, no 31, 22089-22094 p.Article in journal (Refereed) Published
We have previously shown that porcine aortic endothelial cells expressing the Y934F platelet-derived growth factor (PDGF) beta-receptor mutant respond to PDGF-BB in a chemotaxis assay at about 100-fold lower concentration than do wild-type PDGF beta-receptor-expressing cells (Hansen, K., Johnell, M., Siegbahn, A. , Rorsman, C., Engström, U., Wernstedt, C., Heldin, C.-H., and Rönnstrand, L. (1996) EMBO J. 15, 5299-5313). Here we show that the increased chemotaxis correlates with increased activation of phospholipase C-gamma1 (PLC-gamma1), measured as inositol-1,4, 5-trisphosphate release. By two-dimensional phosphopeptide mapping, the increase in phosphorylation of PLC-gamma1 was shown not to be selective for any site, rather a general increase in phosphorylation of PLC-gamma1 was seen. Specific inhibitors of protein kinase C, bisindolylmaleimide (GF109203X), and phosphatidylinositol 3-kinase (PI3-kinase), LY294002, did not affect the activation of PLC-gamma1. To assess whether increased activation of PLC-gamma1 is the cause of the hyperchemotactic behavior of the Y934F mutant cell line, we constructed cell lines expressing either wild-type or a catalytically compromised version of PLC-gamma1 under a tetracycline-inducible promoter. Overexpression and concomitant increased activation of wild-type PLC-gamma1 in response to PDGF-BB led to a hyperchemotactic behavior of the cells, while the catalytically compromised PLC-gamma1 mutant had no effect on PDGF-BB-induced chemotaxis. Furthermore, in cells expressing normal levels of PLC-gamma1, chemotaxis was inhibited by LY294002. In contrast, the increase in chemotactic response seen upon overexpression of PLC-gamma1 was not inhibited by the PI3-kinase inhibitor LY294002. These observations suggest the existence of two different pathways which mediate PDGF-induced chemotaxis; depending on the cellular context, the PI3-kinase pathway or the PLC-gamma1 pathway may dominate.
Place, publisher, year, edition, pages
1999. Vol. 274, no 31, 22089-22094 p.
Phosphatidylinositol 3-Kinase, Chemotaxis, Inositol 1;4;5-TrisphosphatePlatelet-Derived Growth Factor
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-72721DOI: 10.1074/jbc.274.31.22089PubMedID: 10419537OAI: oai:DiVA.org:uu-72721DiVA: diva2:100632