title: Functional analysis of the matricellular protein SPARC with novel monoclonal antibodies.
abstract: SPARC (osteonectin, BM-40) is a matricellular glycoprotein that is expressed in many embryogenic and adult tissues undergoing remodeling or repair. SPARC modulates cellular interaction with the extracellular matrix (ECM), inhibits cell adhesion and proliferation, and regulates growth factor activity. To explore further the function and activity of this protein in tissue homeostasis, we have developed several monoclonal antibodies (MAbs) that recognize distinct epitopes on SPARC. The MAbs bind to SPARC with high affinity and identify SPARC by ELISA, Western blotting, immunoprecipitation, immunocytochemistry, and/or immunohistochemistry. The MAbs were also characterized in functional assays for potential alteration of SPARC activity. SPARC binds to collagen I and laminin-1 through an epitope defined by MAb 293; this epitope is not involved in the binding of SPARC to collagen III. The other MAbs did not interfere with the binding of SPARC to collagen I or III or laminin-1. Inhibition of the anti-adhesive effect of SPARC on endothelial cells by MAb 236 was also observed. Functional analysis of SPARC in the presence of these novel MAbs now confirms that the activities ascribed to this matricellular protein can be assigned to discrete subdomains.
authors.affiliation: Department of Vascular Biology, The Hope Heart Institute, Seattle, Washington 98101, USA.
authors.forename: Mariya T
authors.initials: MT
authors.lastname: Sweetwyne
authors.forename: Rolf A
authors.initials: RA
authors.lastname: Brekken
authors.forename: Gail
authors.initials: G
authors.lastname: Workman
authors.forename: Amy D
authors.initials: AD
authors.lastname: Bradshaw
authors.forename: Juliet
authors.initials: J
authors.lastname: Carbon
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Siadak
authors.forename: Carrie
authors.initials: C
authors.lastname: Murri
authors.forename: E Helene
authors.initials: EH
authors.lastname: Sage
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D016326:Extracellular Matrix Proteins / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D009928:Organ Specificity; D015676:Osteonectin / Q000276:immunology / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D016326:Extracellular Matrix Proteins; D015676:Osteonectin