Mechanisms of regulation of the MacMARCKS gene in macrophages by bacterial lipopolysaccharide

Abstract

Bacterial lipopolysaccharide (LPS) stably induced the protein kinase C substrate, MacMARCKS, in murine resident peritoneal macrophages; initial induction of MacMARCKS mRNA was detected within 15 min and was protein synthesis-independent. This response was observed in the macrophage cell line RAW264, and occurred also in response to plasmid DNA, a partial mimetic of other responses to LPS. In murine bone marrow-derived macrophages, MacMARCKS was expressed constitutively due to induction by macrophage colony-stimulating factor. Nuclear run-on transcription revealed that, like tumor necrosis factor alpha (TNF-alpha), MacMARCKS was transcribed constitutively in RAW264 cells. The MacMARCKS promoter was sequenced to -1.7 kb and the transcription start site determined. Transient transfections of RAW264 cells revealed that the 113-bp GC-rich proximal promoter contained all the elements required for both high basal activity and 15- to 20-fold activation by LPS.