title: Structural determinants in the platelet-derived growth factor alpha-receptor implicated in modulation of chemotaxis.
abstract: Activation of the platelet-derived growth factor (PDGF) beta-receptor leads to cell growth and chemotaxis. The PDGF alpha-receptor also mediates a mitogenic signal, but fails to induce cell migration in certain cell types. To examine this difference in signal transduction, a series of point-mutated PDGF alpha-receptors were analyzed. Porcine aortic endothelial cells expressing mutant PDGF alpha-receptors, in which tyrosine residues 768, 993, or 1018 were changed to phenylalanine residues migrated toward PDGF, whereas wild-type alpha-receptors and mutant alpha-receptors changed at tyrosine residues 720, 944, or 988 failed to migrate. All mutant receptors were mitogenically active and their capacity to activate phosphatidylinositol 3'-kinase and phospholipase C-gamma was not different from that of the wild-type receptor. Tyr-768 was found to be phosphorylated in PDGF-stimulated cells; in the Y768F mutant, there was a considerable increase in phosphorylation of Ser-767. Tyr-993 was not phosphorylated, but mutation of this tyrosine residue to a phenylalanine residue resulted in increased efficiency of phosphorylation on Tyr-988. Tyr-1018 is known to be an autophosphorylation site. Phosphorylated Tyr-768 and Tyr-1018 may bind signal transduction molecules involved in negative modulation of the chemotactic signaling capacity, whereas phosphorylated Tyr-988 may mediate increased chemotaxis. Thus our data indicate that the PDGF alpha-receptor has an intrinsic ability to transduce a chemotactic signal, and that this signal is counteracted by overriding negative signals.
authors.affiliation: Ludwig Institute for Cancer Research, Box 595, Biomedical Center, S-751 24 Uppsala, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Yokote
authors.forename: S
authors.initials: S
authors.lastname: Mori
authors.forename: A
authors.initials: A
authors.lastname: Siegbahn
authors.forename: L
authors.initials: L
authors.lastname: Rönnstrand
authors.forename: C
authors.initials: C
authors.lastname: Wernstedt
authors.forename: C H
authors.initials: CH
authors.lastname: Heldin
authors.forename: L
authors.initials: L
authors.lastname: Claesson-Welsh
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta; D001483:Base Sequence; D000077214:Becaplermin; D002460:Cell Line; D002633:Chemotaxis / Q000187:drug effects; D004730:Endothelium, Vascular / Q000502:physiology*; D004789:Enzyme Activation; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010649:Phenylalanine; D019869:Phosphatidylinositol 3-Kinases; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D017354:Point Mutation; D020574:Proto-Oncogene Proteins c-sis; D020796:Receptor, Platelet-Derived Growth Factor alpha; D017479:Receptors, Platelet-Derived Growth Factor / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine
chemical_list: D007295:Inositol Phosphates; D007527:Isoenzymes; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D010748:Phosphopeptides; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D000077214:Becaplermin; D014443:Tyrosine; D010649:Phenylalanine; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D020796:Receptor, Platelet-Derived Growth Factor alpha; D017479:Receptors, Platelet-Derived Growth Factor; D010738:Type C Phospholipases