ATF and Jun transcription factors, acting through an Ets/CRE promoter module, mediate lipopolysaccharide inducibility of the chemokine RANTES in monocytic Mono Mac 6 cells

The chemokine RANTES is produced by a variety of tissues, including cells o f the monocyte/ macrophage lineage. RANTES expression is rapidly and transi ently up-regulated in primary monocytes and the monocytic cell line Mono Ma c 6 in response to stimulation by the bacterial product lipopolysaccharide (LPS). Transient transfection of Mono Mac 6 cells with RANTES reporter-prom oter deletion constructs, in conjunction with DNase I footprinting and hete rologous reporter gene assays, allowed identification of an LPS-responsive region within the RANTES promoter Electrophoretic mobility shift assays (EM SA), methylation interference and EMSA supershift experiments were used to characterize sequences and transcription factors responsible for this LPS i nducibility. The region, termed RANTES site G [R(G)], contains consensus si tes for Ets and CRE/AP-1-like elements. Site-directed mutagenesis of the Et s site resulted in a loss of only 15 % of promoter activity, while mutation of the CRE/ AP-1 site led to a loss of 40 % of LPS-induced promoter activi ty. The Ets site constitutively binds the Ets family member PU.1. LPS stimu lation leads to an induction of ATF-3 and JunD factor binding to the CRE/AP -1 site. Thus, LPS induction of RANTES transcription is mediated, in part, through the activation and selective binding of ATF and Jun nuclear factors to the R(G) promoter module.