Osteoactivin promotes osteoblast adhesion through HSPG and alphavbeta1 integrin.

Osteoactivin promotes osteoblast adhesion through HSPG and alphavbeta1 integrin.

Moussa Fouad M; Hisijara Israel Arango; Sondag Gregory R; Scott Ethan M; Frara Nagat; Abdelmagid Samir M; Safadi Fayez F

Journal of cellular biochemistry

2014

2014-07

Osteoactivin (OA), also known as glycoprotein nmb (gpnmb) plays an important role in the regulation of osteoblast differentiation and function. OA induced osteoblast differentiation and function in vitro by stimulating alkaline phosphatase (ALP) activity, osteocalcin production, nodule formation, and matrix mineralization. Recent studies reported a role for OA in cell adhesion and integrin binding. In this study, we demonstrate that recombinant osteoactivin (rOA) as a matricellular protein stimulated adhesion, spreading and differentiation of MC3T3-E1 osteoblast-like cells through binding to alphav beta1 integrin and heparan sulfated proteoglycans (HSPGs). MC3T3-E1 cell adhesion to rOA was blocked by neutralizing anti-OA or anti-alphav and beta1 integrin antibodies. rOA stimulated-osteoblast adhesion was also inhibited by soluble heparin and sodium chlorate. Interestingly, rOA stimulated-osteoblast adhesion promoted an increase in FAK and ERK activation, resulting in the formation of focal adhesions, cell spreading and enhanced actin cytoskeleton organization. In addition, differentiation of primary osteoblasts was augmented on rOA coated-wells marked by increased alkaline phosphatase staining and activity. Taken together, these data implicate OA as a matricellular protein that stimulates osteoblast adhesion through binding to alphav beta1 integrin and cell surface HSPGs, resulting in increased cell spreading, actin reorganization, and osteoblast differentiation with emphasis on the positive role of OA in osteogenesis.

3T3 Cells; Actin Cytoskeleton/physiology; ADHESION; Alkaline Phosphatase/biosynthesis; Animals; Antibodies/immunology; Cell Adhesion; Cell Differentiation; Cell Line; Cell Proliferation; Chlorates/pharmacology; Extracellular Signal-Regulated MAP Kinases/biosynthesis; Eye Proteins/genetics/immunology/*metabolism; Focal Adhesion Kinase 1/biosynthesis; Focal Adhesions; Heparan Sulfate Proteoglycans/*metabolism; Heparin/pharmacology; Inbred C57BL; INTEGRIN; Membrane Glycoproteins/genetics/immunology/*metabolism; Mice; OSTEOACTIVIN; OSTEOBLAST; OSTEOBLAST DIFFERENTIATION; Osteoblasts/*physiology; Osteogenesis/physiology; Protein Binding; Rats; Receptors; Recombinant Proteins; Vitronectin/immunology/*metabolism

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

1243–1253

7

115