The platelet-derived growth factor beta-receptor kinase insert confers specific signaling properties to a chimeric fibroblast growth factor receptor.
Signal transduction by tyrosine kinase growth factor receptors involves ligand-induced phosphorylation of substrates for the kinase, resulting in mediation of common or receptor-specific biological signals. We have compared signal transduction pathways for the fibroblast growth factor receptor-1 (FGFR-1), the platelet-derived growth factor beta-receptor (PDGFR-beta), and a chimeric FGFR-1 molecule, FGFRchim, in which the FGFR-1 kinase insert was replaced with that of the PDGFR-beta. The different receptors were characterized and found to be functional as ligand-stimulatable kinases, after expression of the respective human cDNAs in porcine aortic endothelial cells. Substrates for the receptors were analyzed by ligand stimulation of [32P]orthophosphate-labeled cells and immunoprecipitation with phosphotyrosine antiserum. A number of phosphoproteins were induced in all the different types of cells, but components specifically induced after stimulation of FGFR-1 and PDGFR-beta expressing cells could also be detected. Examination of receptor-associated substrates by in vitro kinase assays revealed phosphoproteins of 65 and 85 kDa, which were associated with PDGFR-beta and FGFRchim, but not with FGFR-1. The 85-kDa phosphoprotein could correspond to the regulatory subunit of phosphatidylinositol 3' kinase (PI3-K), since phosphatidylinositol 3' kinase activity was detected after ligand stimulation of FGFRchim- and PDGFR-beta- but not FGFR-1-expressing cells. In addition, ligand stimulation of FGFRchim- and PDGFR-beta-expressing cells, but not FGFR-1-expressing cells, led to induction of actin reorganization in the form of circular membrane ruffling. Thus, replacement of a discrete segment of the intracellular domain of the FGFR-1 with the corresponding stretch from the PDGFR-beta resulted in transfer of PDGFR-beta-specific signaling properties to the chimeric molecule.
Wennström
S
S
Ludwig Institute for Cancer Research, Uppsala Branch, Sweden.
Landgren
E
E
Blume-Jensen
P
P
Claesson-Welsh
L
L
D000595:Amino Acid Sequence; D002678:Chimera; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor; D017479:Receptors, Platelet-Derived Growth Factor; D015398:Signal Transduction; D013379:Substrate Specificity; D013936:Thymidine / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D011956:Receptors, Cell Surface; D017468:Receptors, Fibroblast Growth Factor; D014443:Tyrosine; D005346:Fibroblast Growth Factors; D011494:Protein Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D013936:Thymidine