A shared role for RBF1 and dCAP-D3 in the regulation of transcription with consequences for innate immunity

Previously,we discovered a conserved interaction between rb proteins and the condensin ii protein cap-d3 that is important for ensuring uniform chromatin condensation during mitotic prophase. the drosophila melanogaster homologs rbf1 and dcap-d3 co-localize on non-dividing polytene chromatin,suggesting the existence of a shared,non-mitotic role for these two proteins. here,we show that the absence of rbf1 and dcap-d3 alters the expression of many of the same genes in larvae and adult flies. strikingly,most of the genes affected by the loss of rbf1 and dcap-d3 are not classic cell cycle genes but are developmentally regulated genes with tissue-specific functions and these genes tend to be located in gene clusters. our data reveal that rbf1 and dcap-d3 are needed in fat body cells to activate transcription of clusters of antimicrobial peptide (amp) genes. amps are important for innate immunity,and loss of either dcap-d3 or rbf1 regulation results in a decrease in the ability to clear bacteria. interestingly,in the adult fat body,rbf1 and dcap-d3 bind to regions flanking an amp gene cluster both prior to and following bacterial infection. these results describe a novel,non-mitotic role for the rbf1 and dcap-d3 proteins in activation of the drosophila immune system and suggest dcap-d3 has an important role at specific subsets of rbf1-dependent genes. © 2012 longworth et al.