CELLULAR AND MOLECULAR BIOLOGY
Function of Upd3 in the Drosophila JAK/STAT pathway. SARAH SPECHT,*1 CARLOS
SANDFOSS,*2 TRAVIS SEXTON,2 DUSTIN PERRY,2 and DOUGLAS HARRISON. 1University
of the Cumberlands, Williamsburg, KY. 2Department of Biology, University of Kentucky,
Lexington, KY 40506.
Upd3 is part of the family of Upd ligands that activate the evolutionarily conserved Janus
Kinase/Signal Transducers and Activators of Transcription (JAK/STAT) pathway in Drosophila
melanogaster. The JAK/STAT pathway is essential for proper cell differentiation, cell migration,
and cell proliferation, and has critical functions in the developmental and homeostatic processes of
many organisms. JAK/STAT signaling is important to humans because aberrant signaling is
involved in inflammatory disease, erythrocytosis, gigantism and leukemia. The goal of this project
was to investigate the role Upd3 plays in activating the JAK/STAT pathway in Drosophila
gametogenesis, a process previously known to require JAK signaling. In Drosophila oogenesis, we
found that upd3 mutants have altered differentiation of follicular cells and high rates of unfertilized
eggs, consistent with a phenotype of reduced JAK/STAT activity. Surprisingly, eggs from upd3
mutant mothers were also found to be mildly ventralized, demonstrating a previously unknown role
for the pathway in dorso-ventral axis formation. We also found that upd3 mutant males became
reproductively senescent faster than wild type, perhaps due to the role of JAK in spermatogenic stem
cell maintenance. Lastly, upd3 mutants were shown to have shortened lifespans, suggesting a
possible role in aging. These conclusions support the hypothesis that Upd3 aids Upd in activating the
JAK/STAT pathway in Drosophila.