title: Fibronectin binds and enhances the activity of bone morphogenetic protein 1.
abstract: Bone morphogenetic protein-1-like proteinases play key roles in formation of the extracellular matrix (ECM) in vertebrates via biosynthetic processing of precursors into mature functional proteins involved in ECM assembly. Such processing includes proteolytic activation of the zymogen for lysyl oxidase. Fibronectin (FN) is an abundant protein component of the ECM that is capable of regulating manifold cellular functions through its interactions with various ECM and cell surface proteins. It was previously shown that proteolytic activation of lysyl oxidase is much reduced in cultures of FN-null mouse embryo fibroblasts (MEFs). Here we demonstrate that cellular fibronectin, the form produced by fibroblasts and various other tissue cell types, and plasma fibronectin bind BMP1 with dissociation constants (KD) of approximately 100 nM, consistent with a physiological role. Also consistent with such a role, cellular fibronectin FN is shown to positively regulate BMP1 processing activity against Chordin, probiglycan, and type I procollagen in vitro. Endogenous FN and BMP1 are demonstrated to co-localize in cell layers and to form complexes in culture medium. In addition, processing of endogenous BMP1 substrates Chordin, probiglycan, and procollagen is demonstrated to be strikingly reduced in cultures of FN(-/-) MEFs compared with FN(+/-) MEF cultures despite similar levels of endogenous BMP1. These data support the conclusion that FN binds BMP1-like proteinases in vivo and that FN is an important determinant of the in vivo activity levels of BMP1-like proteinases.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Guorui
authors.initials: G
authors.lastname: Huang
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Byoungjae
authors.initials: B
authors.lastname: Kim
authors.forename: Gaoxiang
authors.initials: G
authors.lastname: Ge
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Annis
authors.forename: Deane F
authors.initials: DF
authors.lastname: Mosher
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Greenspan
mesh_terms: D000818:Animals; D058578:Biglycan; D055395:Bone Morphogenetic Protein 1 / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011347:Procollagen / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity / Q000502:physiology
chemical_list: C546884:BGN protein, human; C546885:Bgn protein, mouse; D058578:Biglycan; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D011347:Procollagen; D011509:Proteoglycans; C054234:chordin; D008249:Protein-Lysine 6-Oxidase; C525705:BMP1 protein, human; C525707:Bmp1 protein, mouse; D055395:Bone Morphogenetic Protein 1