DIFFERENTIAL REGULATION OF VITRONECTIN IN MICE AND HUMANS IN-VITRO

To define the cis-acting elements involved in the regulation of the mu rine vitronectin (Vn) gene in inflammation, the 5'-flanking region was isolated, fused to the luciferase reporter gene, and the basal and in terleukin 6 (IL-6)-stimulated transcriptional activity was tested in t ransfection experiments using Hep3B cells. Treatment with IL-6 induced this construct by more than 20-fold, whereas the corresponding 5'-fla nking region of the human Vn gene was not stimulated. Transfection stu dies using murine Vn constructs with serial 5' deletions revealed that two sequences were important in the IL-6 response, and specific mutat ions in both sequences abolished the response. A 2-base pair mutation converted the human sequence to that of a murine IL-6 responsive eleme nt and partially conveyed IL-6 inducibility. In contrast, transforming growth factor beta stimulated the human construct and the endogenous Vn gene in human Hep3B cells in a dose-dependent manner, whereas the m urine construct was not responsive. The transforming growth factor bet a responsive region was localized to a 30-base pair fragment with litt le homology to the murine sequence. These studies reveal that the stru ctural basis for the differential regulation of the human and murine V n genes resides in the differences in promoter sequence.