1. JAK/STAT and EGFR signaling pattern the follicle cells and establish the A/P axis of the developing Drosophila egg.
JAK/STAT and EGFR signaling pattern the follicle cells and establish the A/P axis of the developing Drosophila egg. A) The polar cells (red) secrete the JAK/STAT signaling ligand Unpaired (cyan). Unpaired activates JAK/STAT signaling activity in the follicle cell (FC) poles (yellow) by stage 5 (S5) to specify the AFCs and presumptive PFCs (pre-PFCs). Main body FCs are indicated. FCs become competent to respond to the JAK/STAT signal at stage 6, following Notch signaling (light green). B) Gurken/EGFR signaling (light purple) specifies the PFCs at stage 6/7 (S6/7). Once specified, the PFCs signal (arrows) to direct oocyte repolarization. During repolarization, the oocyte nucleus (magenta) migrates to the dorsoanterior (DA) corner, bicoid RNA (bcd, blue) accumulates at the anterior, and oskar RNA (osk, green) localizes to the posterior. At stage 9 (S9), Gurken/EGFR signaling specifies the DA follicle cells.
Julia Wittes, and Trudi Schüpbach G3 2018;9:47-60
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