title: Heparin amplifies platelet-derived growth factor (PDGF)- BB-induced PDGF alpha -receptor but not PDGF beta -receptor tyrosine phosphorylation in heparan sulfate-deficient cells. Effects on signal transduction and biological responses.
abstract: Platelet-derived growth factor (PDGF) induces mitogenic and migratory responses in a wide variety of cells, by activating specific receptor tyrosine kinases denoted the PDGF alpha- and beta-receptors. Different PDGF isoforms bind in a distinct manner to glycosaminoglycans, particularly heparan sulfate. In the present study, we show potentiation by exogenous heparin of PDGF-BB-induced PDGF alpha-receptor tyrosine phosphorylation in heparan sulfate-deficient Chinese hamster ovary (CHO) 677 cells. This effect was not seen for PDGF-AA treatment, and heparin lacked a potentiating effect on PDGF-BB stimulation of the PDGF beta-receptor. Heparin did not affect the affinity of PDGF-BB binding for the PDGF receptors on CHO 677 cells. The PDGF-BB-stimulated PDGF alpha-receptor phosphorylation was enhanced in a dose-dependent fashion by heparin at low concentration. The effect was modulated by 2-O- and 6-O-desulfation of the polysaccharide. Maximal induction of PDGF alpha-receptor tyrosine phosphorylation (6-fold) in CHO 677 cells was achieved by treatment with a heparin decasaccharide, but shorter oligosaccharides consisting of four or more monosaccharide units were also able to augment PDGF alpha-receptor phosphorylation, albeit at higher concentrations. Heparin potentiated PDGF-BB-induced activation of mitogen-activated protein kinase and protein kinase B (Akt) and allowed increased chemotaxis of the CHO 677 cells toward PDGF-BB. In conclusion, heparin modulates PDGF-BB-induced PDGF alpha-receptor phosphorylation and downstream signaling, with consequences for cellular responsiveness to the growth factor.
authors.affiliation: Department of Genetics and Pathology, Uppsala University, Rudbeck Laboratory, Dag Hammarskjölds v. 20, 751 85 Uppsala, Sweden.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Rolny
authors.forename: Dorothe
authors.initials: D
authors.lastname: Spillmann
authors.forename: Ulf
authors.initials: U
authors.lastname: Lindahl
authors.forename: Lena
authors.initials: L
authors.lastname: Claesson-Welsh
mesh_terms: D000818:Animals; D000077214:Becaplermin; D016466:CHO Cells; D002465:Cell Movement; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D006025:Glycosaminoglycans / Q000378:metabolism; D006493:Heparin / Q000737:chemistry* / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism*; D015151:Immunoblotting; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D020033:Protein Isoforms; D020574:Proto-Oncogene Proteins c-sis; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000737:chemistry / Q000378:metabolism*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D000077214:Becaplermin; D006025:Glycosaminoglycans; D006493:Heparin; D006497:Heparan Sulfate; D010982:Platelet-Derived Growth Factor; D011134:Polysaccharides; D020033:Protein Isoforms; D020574:Proto-Oncogene Proteins c-sis; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta; D014443:Tyrosine