title: A secreted collagen- and fibronectin-binding streptococcal protein modulates cell-mediated collagen gel contraction and interstitial fluid pressure.
abstract: Fibroblast-mediated collagen gel contraction depends on collagen-binding beta1 integrins. Perturbation of these integrins reveals an alternative contraction process that is integrin alphaVbeta3-dependent and platelet-derived growth factor (PDGF) BB-stimulated. Connective tissue cells actively control interstitial fluid pressure (IFP), and inflammation-induced lowering of IFP provides a driving force for edema formation. PDGF-BB normalizes a lowered IFP by an alphaVbeta3-dependent process. A potential modulation of IFP by extracellular matrix-binding bacterial proteins has previously not been addressed. The fibronectin (FN)-binding protein FNE is specifically secreted by the highly virulent Streptococcus equi subspecies equi. FNE bound FN and native collagen type I with K(d) values of approximately 20 and approximately 50 nm determined by solid-phase binding assays. Rotary shadowing revealed a single FNE binding site located at on average 122 nm from the C terminus of procollagen type I. FNE induced alphaVbeta3-mediated contraction by C2C12 cells in a concentration-dependent manner having a maximal effect at approximately 100 nm. This activity of FNE required cellular FN, and FNE acted synergistically to added plasma FN or PDGF-BB. FNE enhanced binding of soluble FN to immobilized collagen, and conversely the binding of collagen to immobilized FN. Marked bell-shaped concentration dependences for these interactions suggest that FNE forms a bridge between FN and collagen. Finally, FNE normalized dermal IFP lowered by anaphylaxis. Our data suggest that secreted FNE normalized lowering of IFP by stimulating connective tissue cell contraction.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-751 23 Uppsala, Sweden; Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
authors.forename: Åsa
authors.initials: Å
authors.lastname: Lidén
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.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Lannergård
authors.affiliation: Department of Experimental Medical Sciences, BMC, B-12, University of Lund, SE-221 84 Lund, Sweden.
authors.forename: Anja
authors.initials: A
authors.lastname: Kassner
authors.affiliation: Department of Experimental Medical Sciences, BMC, B-12, University of Lund, SE-221 84 Lund, Sweden.
authors.forename: Dick
authors.initials: D
authors.lastname: Heinegård
authors.affiliation: Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
authors.forename: Rolf K
authors.initials: RK
authors.lastname: Reed
authors.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Guss
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-751 23 Uppsala, Sweden. Electronic address: Kristofer.Rubin@imbim.uu.se.
authors.forename: Kristofer
authors.initials: K
authors.lastname: Rubin
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000378:metabolism*; D000707:Anaphylaxis; D000818:Animals; D002417:Cattle; D002448:Cell Adhesion; D002460:Cell Line; D003094:Collagen / Q000378:metabolism*; D024042:Collagen Type I / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D045604:Extracellular Fluid / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D005782:Gels; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D032446:Myoblasts / Q000166:cytology*; D011312:Pressure; D011485:Protein Binding; D012995:Solubility; D013291:Streptococcus / Q000378:metabolism*
chemical_list: D018829:Adhesins, Bacterial; D024042:Collagen Type I; D005353:Fibronectins; D005782:Gels; D039302:Integrin alphaVbeta3; C078635:fibronectin-binding proteins, bacterial; D003094:Collagen