Drosophila melanogaster is an important model system in which to study innate immunity, being both easy to manipulate and lacking an adaptive immune system. To identify genes that regulate innate immunity, Cronin et al. performed an RNA interference screen on flies infected with the oral bacterial pathogen Serratia marcescens. Genes involved in intestinal immunity and regulation of hemocytes, macrophage-like cells critical for phagocytosis and killing of the bacteria, were identified. Several hundred genes conferred either enhanced susceptibility or resistance to bacterial infection. Furthermore, the Janus kinase–signal transducer and activator of transcription (JAK-STAT) signaling pathway was activated in intestinal stem cells after bacterial infection, resulting in enhanced susceptibility to infection, most likely through regulation of intestinal stem cell homeostasis.
S. J. F. Cronin, N. T. Nehme, S. Limmer, S. Liegeois, J. A. Pospisilik, D. Schramek, A. Leibbrandt, R. de Matos Simoes, S. Gruber, U. Puc, I. Ebersberger, T. Zoranovic, G. G. Neely, A. von Haeseler, D. Ferrandon, J. M. Penninger, Genome-wide RNAi screen identifies genes involved in intestinal pathogenic bacterial infection. Science 325, 340–343 (2009). [Abstract] [Full Text]