AIM: We previously showed that cellular repressor of E1A-stimulated genes (CREG) is up-regulated during serum starvation-induced vascular smooth muscle cell (SMC) differentiation. The aim of this study was to determine the role of CREG in maintaining the quiescent, differentiated phenotype of SMCs both in culture and in balloon-injured rat carotid artery. METHODS AND RESULTS: In cultured SMCs recombinant virus-mediated CREG expression enhanced cellular differentiation, inhibited proliferation, and reduced synthesis of extracellular matrix component fibronectin. In contrast, CREG knockdown via retroviral transfer of short hairpin RNAs abrogated serum starvation-induced SMC differentiation and growth arrest. Both immunostaining and Western analysis demonstrated marked down-regulation of CREG in the vascular media after balloon injury to the rat carotid artery. Retrovirus-mediated CREG transfer to the injured artery inhibited SMC dedifferentiation and proliferation, and reduced neointimal hyperplasia. CONCLUSION: These results suggest that CREG participates in the maintenance of quiescent mature SMC phenotype in the arterial media by promoting SMC differentiation and growth arrest and that CREG gene transfer has therapeutic potential for vascular diseases associated with neointimal hyperplasia.
AIM: We previously showed that cellular repressor of E1A-stimulated genes (CREG) is up-regulated during serum starvation-induced vascular smooth muscle cell (SMC) differentiation. The aim of this study was to determine the role of CREG in maintaining the quiescent, differentiated phenotype of SMCs both in culture and in balloon-injured rat carotid artery. METHODS AND RESULTS: In cultured SMCs recombinant virus-mediated CREG expression enhanced cellular differentiation, inhibited proliferation, and reduced synthesis of extracellular matrix component fibronectin. In contrast, CREG knockdown via retroviral transfer of short hairpin RNAs abrogated serum starvation-induced SMC differentiation and growth arrest. Both immunostaining and Western analysis demonstrated marked down-regulation of CREG in the vascular media after balloon injury to the rat carotid artery. Retrovirus-mediated CREG transfer to the injured artery inhibited SMC dedifferentiation and proliferation, and reduced neointimal hyperplasia. CONCLUSION: These results suggest that CREG participates in the maintenance of quiescent mature SMC phenotype in the arterial media by promoting SMC differentiation and growth arrest and that CREG gene transfer has therapeutic potential for vascular diseases associated with neointimal hyperplasia.