Functional analysis of the matricellular protein SPARC with novel monoclonal antibodies.
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.
Sweetwyne
Mariya T
MT
Department of Vascular Biology, The Hope Heart Institute, Seattle, Washington 98101, USA.
Brekken
Rolf A
RA
Workman
Gail
G
Bradshaw
Amy D
AD
Carbon
Juliet
J
Siadak
Anthony W
AW
Murri
Carrie
C
Sage
E Helene
EH
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
D000911:Antibodies, Monoclonal; D000939:Epitopes; D016326:Extracellular Matrix Proteins; D015676:Osteonectin