title: Integrin alphavbeta3 mediates platelet-derived growth factor-BB-stimulated collagen gel contraction in cells expressing signaling deficient integrin alpha2beta1.
abstract: The interplay between the collagen-binding integrin, alpha2beta1, and platelet-derived growth factor (PDGF) receptors in the context of functional interactions with collagen was studied. We expressed either wild-type alpha2beta1 (alpha2beta1A) or alpha2beta1 with a Y783/795F mutation in the cytoplasmic tail of the beta1 subunit (alpha2beta1Amut) in the beta1-null fibroblastic cell line, GD25. GD25 cells lack endogenous expression of the alpha1 and alpha2 integrin subunits and do not adhere to collagen even after transfection with beta1A. Cells expressing alpha2beta1Amut contracted three-dimensional collagen lattices less efficiently than those expressing alpha2beta1A. PDGF-BB significantly stimulated lattice contraction by GD25-alpha2beta1Amut cells. Both cell types responded chemotactically to PDGF-BB. Focal adhesion kinase (FAK) and p130(Cas) were phosphorylated when GD25-alpha2beta1A cells, but not GD25-alpha2beta1Amut cells were seeded on collagen-coated dishes. Subsequent treatment with PDGF-BB further increased phosphorylation of FAK and p130(Cas) only in GD25-alpha2beta1A cells. However, when cultured within collagen lattices, FAK and p130(Cas) phosphorylation were stimulated in both alpha2beta1A- and alpha2beta1Amut-expressing cells but further phosphorylation, in response to subsequent treatment with PDGF-BB, was seen only in GD25-alpha2beta1A cells. We show that the stimulatory effects of PDGF-BB on collagen gel contraction and chemotaxis by GD25-alpha2beta1Amut cells were mediated by the alphavbeta3 integrin. Phosphorylation of p130(Cas), but not FAK, in GD25-alpha2beta1Amut cells seeded in collagen lattices also depended on alphavbeta3. Our results show that PDGF-BB stimulation of fibroblast-collagen interactions is mediated by the alphavbeta3 integrin when beta1 integrin function is impaired.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-751 23 Uppsala, Sweden.
authors.forename: Gunilla
authors.initials: G
authors.lastname: Grundström
authors.forename: Deane F
authors.initials: DF
authors.lastname: Mosher
authors.forename: Takao
authors.initials: T
authors.lastname: Sakai
authors.forename: Kristofer
authors.initials: K
authors.lastname: Rubin
mesh_terms: D000818:Animals; D000077214:Becaplermin; D002460:Cell Line; D002633:Chemotaxis; D024042:Collagen Type I / Q000378:metabolism*; D050719:Crk-Associated Substrate Protein; D005347:Fibroblasts / Q000166:cytology*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D038982:Integrin alpha2beta1 / Q000172:deficiency* / Q000235:genetics; D039302:Integrin alphaVbeta3 / Q000502:physiology*; D051379:Mice; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins; D020574:Proto-Oncogene Proteins c-sis; D020239:Receptor Cross-Talk; D017479:Receptors, Platelet-Derived Growth Factor; D050717:Retinoblastoma-Like Protein p130; D015398:Signal Transduction; D014162:Transfection
chemical_list: C493842:Bcar1 protein, mouse; D024042:Collagen Type I; D050719:Crk-Associated Substrate Protein; D038982:Integrin alpha2beta1; D039302:Integrin alphaVbeta3; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D011506:Proteins; D020574:Proto-Oncogene Proteins c-sis; D050717:Retinoblastoma-Like Protein p130; D000077214:Becaplermin; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse