To elucidate one arm of the innate immune system in the Drosophila fruitfly, Edan Foley and Patrick O'Farrell sequentially silenced its conserved genes (over 7,000) to study the effect on the flies ability to mount an immune response. Their findings, published on-line in the open-access journal PLoS Biology, not only add to our understanding of the highly conserved innate immune system, but they have also demonstrated that a global genome silencing approach is feasible for elucidating complex molecular signaling systems.
Specifically they examined the Immune deficiency (Imd) pathway. Bacterial pathogens stimulate a transmembrane receptor, which activates the Imd protein, which then transmits the signal through intermediary proteins into the nucleus, to activate genes required for an immune response. Although this outline of the immune response is understood, the signaling pathway involves countless other uncharacterized interactions. To identify pertinent genes and their roles, Foley and O'Farrell took advantage of a technique, called RNA interference (RNAi), that can selectively target and "silence," or inhibit, nearly any gene. The authors silenced all Drosophila genes that had counterparts in mammals or the worm C. elegans (which share the fundamental properties of this innate immune response).
Foley and O'Farrell's RNAi screen identified many molecules involved in signaling, including two new genes: one, which they named sickie, is required to cause the protein Relish to move into the nucleus to activate gene expression; the second, c
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Contact: Philip Bernstein
pbernstein@plos.org
415-624-1210
Public Library of Science
22-Jun-2004