title: CD47 regulates collagen I-induced cyclooxygenase-2 expression and intestinal epithelial cell migration.
abstract: Increased epithelial cell expression of the cyclooxygenase-2 (COX-2) enzyme is a characteristic event of both inflammatory bowel disease and colon cancer. We here report the novel findings that collagen I-induced de novo synthesis of COX-2 in intestinal epithelial cells is inhibited by pertussis toxin (PTX) and by an inhibitory peptide selective for the heterotrimeric G alpha(i3)-protein. These findings could be explained by a regulatory involvement of the G-protein-dependent integrin-associated protein CD47. In support of this notion, we observed a collagen I-induced association between CD47 and alpha2 integrins. This association was reduced by a blocking anti-CD47 antibody but not by PTX or a control anti-beta2 antibody. Furthermore, a blocking antibody against CD47, dominant negative CD47 or specific siRNA knock down of CD47, significantly reduced collagen I-induced COX-2 expression. COX-2 has previously been shown to regulate intestinal epithelial cell adhesion and migration. Morphological analysis of intestinal cells adhering to collagen I revealed a co-localisation of CD47 and alpha2 integrins to non-apoptotic membrane blebs enriched in Rho A and F-actin. The blocking CD47 antibody, PTX and a selective COX-2 inhibitor, dramatically inhibited the formation of these blebs. In accordance, migration of these cells on a collagen I-coated surface or through a collagen I gel were significantly reduced by the CD47 blocking antibody, siRNA knock down of CD47 and the COX-2 inhibitor NS-398. In conclusion, we present novel data that identifies the G-protein-dependent CD47 protein as a key regulator of collagen I-induced COX-2 expression and a promoter of intestinal epithelial cell migration.
authors.affiliation: Cell and Experimental Pathology, Department of Laboratory Medicine, Lund University, Clinical Research Centre, Malmö University Hospital (UMAS), Malmö, Sweden.
authors.forename: Oliver Jay
authors.initials: OJ
authors.lastname: Broom
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Per-Arne
authors.initials: PA
authors.lastname: Oldenborg
authors.forename: Ramin
authors.initials: R
authors.lastname: Massoumi
authors.forename: Anita
authors.initials: A
authors.lastname: Sjölander
mesh_terms: D015153:Blotting, Western; D051928:CD47 Antigen / Q000276:immunology*; D002465:Cell Movement / Q000276:immunology*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000502:physiology*; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D004790:Enzyme Induction; D006801:Humans; D047468:Immunoprecipitation; D007413:Intestinal Mucosa / Q000166:cytology*
chemical_list: D051928:CD47 Antigen; D024042:Collagen Type I; D051546:Cyclooxygenase 2