CCN2, connective tissue growth factor, stimulates collagen deposition by gingival fibroblasts via module 3 and alpha6- and beta1 integrins

CCN2, (connective tissue growth factor, CTGF) is a matricellular factor associated with fibrosis that plays an important role in the production and maintenance of fibrotic lesions. Increased collagen deposition and accumulation is a common feature of fibrotic tissues. The mechanisms by which CCN2/CTGF contributes to fibrosis are not well understood. Previous studies suggest that CTGF exerts some of its biological effects at least in part by integrin binding, though this mechanism has not been previously shown to contribute to fibrosis. Utilizing full length CCN2/CTGF, CCN2/CTGF fragments, and integrin neutralizing antibodies, we provide evidence that the effects of CCN2/CTGF to stimulate extracellular matrix deposition by gingival fibroblasts are mediated by the C-terminal half of CCN2/CTGF, and by alpha6 and beta1 integrins. In addition, a synthetic peptide corresponding to a region of CCN2/CTGF domain 3 that binds alpha6beta1 inhibits the collagen-deposition assay. These studies employed a new and relatively rapid assay for CCN2/CTGF-stimulated collagen deposition based on Sirius Red staining of cell layers. Data obtained support a pathway in which CCN2/CTGF could bind to alpha6beta1 integrin and stimulate collagen deposition. These findings provide new experimental methodologies applicable to uncovering the mechanism and signal transduction pathways of CCN2/CTGF-mediated collagen deposition, and may provide insights into potential therapeutic strategies to treat gingival fibrosis and other fibrotic conditions.