A Striking Similarity in the Organization of the E-Selectin and Bate Interferon gene Promoters

Abstract

Transcription of the endothelial leukocyte adhesion molecule 1 (E-selectin or ELAM-1) gene is induced by the inflammatory cytokines interleukin-1β and tumor necrosis factor α (TNF-α). In this report, we identify four positive regulatory domains (PDI to PDIV) in the E-selectin promoter that are required for maximal levels of TNF-α induction in endothelial cells. In vitro DNA binding studies reveal that two of the domains contain novel adjacent binding sites for the transcription factor NF-κ B (PDIII and PDIV), a third corresponds to a recently described CRE/ATF site (PDII), and a fourth is a consensus NF-κ B site (PDI). Mutations that decrease the binding of NF-κ B to any one of the NF-κ B binding sites in vitro abolished cytokine-induced E-selectin gene expression in vivo. Previous studies demonstrated a similar correlation between ATF binding to PDII and E-selectin gene expression. Here we show that the high-mobility-group protein I(Y) [HMG I(Y)] also binds specifically to the E-selectin promoter and thereby enhances the binding of both ATF-2 and NF-κ B to the E-selectin promoter in vitro. Moreover, mutations that interfere with HMG I(Y) binding decrease the level of cytokine-induced E-selectin expression. The organization of the TNF-α-inducible element of the E-selectin promoter is remarkably similar to that of the virus-inducible promoter of the human β interferon gene in that both promoters require NF-κ B, ATF-2, and HMG I(Y). We propose that HMG I(Y) functions as a key architectural component in the assembly of inducible transcription activation complexes on both promoters.