Individual domains of connective tissue growth factor regulate fibroblast proliferation and myofibroblast differentiation.

All members of the Ctgf, Cyr61, and Nov (CCN) family share a high degree of sequence homology and conservation of structural motifs and domains. Here, we present data about a structure function analysis of connective tissue growth factor (CTGF), a prototypic member of the CCN family, which has been shown to be a downstream mediator of transforming growth factor-beta activities on fibroblasts. Our findings demonstrate the two domains of CTGF function to mediate two distinct biological effects. The N-terminal domain of CTGF mediates myofibroblast differentiation and collagen synthesis. The C-terminal domain of CTGF mediates fibroblast proliferation. These data provide a molecular basis for the divergence of CTGF actions on connective tissue cell types and suggest a model for functional analysis of all of the CCN family gene products.