BETA-IG-H3, A NOVEL SECRETORY PROTEIN INDUCIBLE BY TRANSFORMING GROWTH-FACTOR-BETA, IS PRESENT IN NORMAL SKIN AND PROMOTES THE ADHESION ANDSPREADING OF DERMAL FIBROBLASTS IN-VITRO

We have previously identified a gene, beta ig-h3, which is highly indu ced in A549 cells (human lung adenocarcinoma) after growth arrest by t ransforming growth factor-beta. The beta ig-h3 gene encodes a 683-amin o-acid secretory protein termed beta IG-H3, and treatment of several c ell lines with transforming growth factor-p results in increased secre tion of beta IG-H3 into cell culture supernatants. In this report, we further characterize beta IG-H3 with respect to its synthesis and func tion. Primary human foreskin fibroblasts grown in monolayer culture pr oduced beta IG-H3 mRNA and secreted beta IG-H3 protein into the growth media. Treatment of these cells with transforming growth factor-beta led to an increase in beta IG-H3 mRNA and protein. Cells grown on thre e-dimensional scaffolds secreted beta IG-H3 into the extracellular mat rix, as judged by immunostaining with anti-beta IG-H3 antibodies, beta IG-H3 was also detected in normal human skin, especially in the papil lary dermis. Finally, we show that recombinant beta IG-H3 supported at tachment and spreading of dermal fibroblasts, suggesting that beta IG- H3 may function as an extracellular attachment protein in skin.