The roles of the Drosophila JAK/STAT pathway

The JAK/STAT signal transduction pathway has been conserved throughout evol ution such that true structural and functional homologues of components ori ginally identified in vertebrate systems are also present in the model gene tic system Drosophila melanogaster. In addition to roles during larval hema topoiesis reminiscent of the requirement for this pathway in mammalian syst ems, the JAK/STAT pathway in Drosophila is also involved in a number of oth er developmental events. Recent data has demonstrated further roles for the JAK/STAT pathway in the establishment of sexual identity via the early emb ryonic expression of Sex lethal. the segmentation of the embryo via the con trol of pair rule genes including even skipped and the establishment of pol arity within the adult compound eye via a mechanism that includes the four jointed gene, Use of the powerful genetics in the model organism Drosophila may identify new components of the JAK/STAT pathway, define new roles for this pathway, and provide insights into the function of this signal transdu ction system. Here we review the roles of STAT and its associated signaling pathway during both embryonic and adult stages of Drosophila development a nd discuss future prospects for the identification and characterization of novel pathway components and targets.