Transglutaminase-mediated oligomerization promotes osteoblast adhesive properties of osteopontin and bone sialoprotein
Volume 5, Issue 1
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Pages 65 - 72http://dx.doi.org/10.4161/cam.5.1.13369
Authors: Jennifer Forsprecher, Zhemeng Wang, Harvey A. Goldberg and Mari T. Kaartinen View affiliations
Tissue transglutaminase (TG2) is a widely distributed, protein-crosslinking enzyme having a prominent role in cell adhesion as a β1 integrin co-receptor for fibronectin. In bone and teeth, its substrates include the matricellular proteins osteopontin (OPN) and bone sialoprotein (BSP). The aim of this study was to examine effects of TG2-mediated crosslinking and oligomerization of OPN and BSP on osteoblast cell adhesion. We show that surfaces coated with oligomerized OPN and BSP promote MC3T3-E1/C4 osteoblastic cell adhesion significantly better than surfaces coated with the monomeric form of the proteins. Both OPN and BSP oligomer-adherent cells showed more cytoplasmic extensions than those cells grown on the monomer-coated surfaces indicative of increased cell connectivity. Our study suggests a role for TG2 in promoting the cell adhesion function of two matricellular substrate proteins prominent in bone, tooth cementum and certain tumors.
Received: June 10, 2010; Accepted: August 19, 2010