title: Transglutaminase-mediated oligomerization promotes osteoblast adhesive properties of osteopontin and bone sialoprotein.
abstract: 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.
authors.affiliation: Division of Biomedical Sciences, Faculty of Dentistry, McGill University, Montreal, QC, CA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Forsprecher
authors.forename: Zhemeng
authors.initials: Z
authors.lastname: Wang
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Goldberg
authors.forename: Mari T
authors.initials: MT
authors.lastname: Kaartinen
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D003739:Dental Cementum / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism; D058574:Integrin-Binding Sialoprotein / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D053495:Osteopontin / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D014070:Tooth / Q000378:metabolism; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D019012:Integrin beta1; D058574:Integrin-Binding Sialoprotein; D053495:Osteopontin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins