Immune stimulation of Anopheles gambiae 4a3B cells induces chromatin reorganization at the Defensin 1 gene

Abstract

Mosquito innate immunity is a critical component in the transmission of Plasmodium parasites that cause malaria in human populations. Molecular mechanisms involved in regulation of transcription of mosquito innate immunity genes are not yet fully understood. Here, the chromatin conformation at the Defensin 1 (Def1) gene was investigated in the Anopheles gambiae derived, immune-responsive, 4a3B cell line. Our aim was to characterize chromatin structure, before and after immune challenge, at this innate immunity gene. Here we report that, upon immune stimulation with a heat-killed bacterial challenge, Def1 promoter sequences become co-localized with an open chromatin site. This indicates that the Def1 promoter undergoes a dynamic chromatin transition upon immune challenge. In contrast, promoter-flanking sequences and exon sequences were not nucleosome depleated in the same samples, obtained from immune stimulated cell cultures. Taken together, these results suggest participation of chromatin modification in the transcriptional activation of the Def1 gene.