Connective tissue growth factor (CCN2) in rat pancreatic stellate cell function:: Integrin ζ5β1 as a novel CCN2 receptor

Background & Aims: Pancreatic stellate cells (PSCs) are proposed to play a key role in the development of pancreatic fibrosis. The aim of this study was to evaluate the production by rat activated PSCs of the fibrogenic protein, connective tissue growth factor (CCN2), and to determine the effects of CCN2 on PSC function. Methods: CCN2 production was evaluated by immunoprecipitation and promoter activity assays. Expression of integrin alpha 5 beta(1) was examined by immunoprecipitation and Western blot. Binding between CCN2 and integrin alpha(5)beta(1) was determined in cell-free systems. CCN2 was assessed for its stimulation of PSC adhesion, migration, proliferation, DNA synthesis, and collagen I synthesis. Results: CCN2 was produced by activated PSCs, and its levels were enhanced by transforming growth factor beta(1) treatment. CCN2 promoter activity was stimulated by transforming growth factor 0:1, platelet-derived growth factor, alcohol, or acetaldehyde. CCN2 stimulated integrin alpha(5)beta(1)-dependent adhesion, migration, and collagen I synthesis in PSCs. Integrin alpha(5)beta(1) production by PSCs was verified by immunoprecipitation, while direct binding between integrin alpha(5)beta(1) and CCN2 was confirmed in cell-free binding assays. Cell surface heparan sulfate proteoglycans functioned as a partner of integrin alpha(5)beta(1) in regulating adhesion of PSCs to CCN2. PSC proliferation and DNA synthesis were enhanced by CCN2. Conclusions: PSCs synthesize CCN2 during activation and after stimulation by profibrogenic molecules. CCN2 regulates PSC function via cell surface integrin alpha(5)beta(1) and heparan sulfate proteoglycan receptors. These data support a role for CCN2 in PSC-mediated fibrogenesis and highlight CCN2 and its receptors as potential novel therapeutic targets.