title: The streptococcal collagen-binding protein CNE specifically interferes with alphaVbeta3-mediated cellular interactions with triple helical collagen.
abstract: Collagen fibers expose distinct domains allowing for specific interactions with other extracellular matrix proteins and cells. To investigate putative collagen domains that govern integrin α(V)β(3)-mediated cellular interactions with native collagen fibers we took advantage of the streptococcal protein CNE that bound native fibrillar collagens. CNE specifically inhibited α(V)β(3)-dependent cell-mediated collagen gel contraction, PDGF BB-induced and α(V)β(3)-mediated adhesion of cells, and binding of fibronectin to native collagen. Using a Toolkit composed of overlapping, 27-residue triple helical segments of collagen type II, two CNE-binding sites present in peptides II-1 and II-44 were identified. These peptides lack the major binding site for collagen-binding β(1) integrins, defined by the peptide GFOGER. Peptide II-44 corresponds to a region of collagen known to bind collagenases, discoidin domain receptor 2, SPARC (osteonectin), and fibronectin. In addition to binding fibronectin, peptide II-44 but not II-1 inhibited α(V)β(3)-mediated collagen gel contraction and, when immobilized on plastic, supported adhesion of cells. Reduction of fibronectin expression by siRNA reduced PDGF BB-induced α(V)β(3)-mediated contraction. Reconstitution of collagen types I and II gels in the presence of CNE reduced collagen fibril diameters and fibril melting temperatures. Our data indicate that contraction proceeded through an indirect mechanism involving binding of cell-produced fibronectin to the collagen fibers. Furthermore, our data show that cell-mediated collagen gel contraction does not directly depend on the process of fibril formation.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-751 23 Uppsala, Sweden.
authors.forename: Tijs
authors.initials: T
authors.lastname: van Wieringen
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kalamajski
authors.forename: Asa
authors.initials: A
authors.lastname: Lidén
authors.forename: Dominique
authors.initials: D
authors.lastname: Bihan
authors.forename: Bengt
authors.initials: B
authors.lastname: Guss
authors.forename: Dick
authors.initials: D
authors.lastname: Heinegård
authors.forename: Richard W
authors.initials: RW
authors.lastname: Farndale
authors.forename: Kristofer
authors.initials: K
authors.lastname: Rubin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D000077214:Becaplermin; D001667:Binding, Competitive; D002152:Calorimetry, Differential Scanning; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D003094:Collagen / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000235:genetics / Q000378:metabolism*; D008854:Microscopy, Electron; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D020574:Proto-Oncogene Proteins c-sis; D034622:RNA Interference; D038981:Receptors, Collagen / Q000235:genetics / Q000378:metabolism*; D013291:Streptococcus / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D001426:Bacterial Proteins; D005353:Fibronectins; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D038981:Receptors, Collagen; D000077214:Becaplermin; D003094:Collagen