JAK/Stat signaling in the D. melanogaster cellular immune response. Susanna E. Brantley, Nathan Mortimer, Todd Schlenke. Biology, Emory University, Atlanta, GA.

   The JAK/Stat pathway is a conserved signaling cascade involved in development and cell proliferation in Drosophila and other lineages, including vertebrates. Recent reviews cite the important role of JAK/Stat signaling in vertebrate innate immunity, autoimmunity, leukemias, and lymphomas. Our lab studies the immune response of Drosophila after attack by parasitic wasps, a cellular immune response that may depend on JAK/Stat activity. In this response, hematopoiesis and hemocyte differentiation lead to increased numbers of blood cells called lamellocytes, which are actively involved in the encapsulation of wasp eggs. Gain-of-function mutations in JAK/Stat pathway genes have been shown to induce lamellocyte differentiation in unattacked flies. Here we use two fly strains to delineate the role of JAK/Stat in the encapsulation response more closely: a StatGFP reporter and a fly with a gain of function mutation in Drosophila JAK (hopscotch). We show that JAK/Stat signaling is activated in specific temporal and spatial patterns in response to infection by avirulent wasps. Furthermore, we show that some virulent wasps upset lamellocyte differentiation signaling via the JAK/Stat pathway as a virulence strategy.