A novel association between clustered NF‐κB and C/EBP binding sites is required for immune regulation of mosquito Defensin genes

A comparative analysis identified key cis ‐acting regulatory elements responsible for the temporal control of mosquito Defensin gene expression. The promoters of Anopheles gambiae Defensin 1 and two isoforms of Aedes aegypti Defensin A are up‐regulated by immune challenge. This stimulated activity depends upon a cluster of three NF‐κB binding sites and closely associated C/EBP‐like motifs, which function as a unit for optimal promoter activity. Binding of NF‐κB and C/EBP like transcription factors is confirmed by electrophoretic mobility shift assay, including supershifts with antibodies to C/EBP. κB‐like motifs are abundant within antimicrobial peptide gene promoters and most are very closely associated with putative C/EBP binding sites. This novel association between NF‐κB and C/EBP binding sites may, therefore, be of widespread significance.