Figure 6. N/Src synergy activates the JAK/STAT signaling pathway.
(A) qPCR for unpaired family ligands in vgGal4 discs expressing UAS constructs as indicated. All three upd family genes are highly upregulated by the combination of Nact and Src42ACA (dark purple bars), and this upregulation is dependent upon JNK signaling as BskDN rescues it (lavender bars). Coexpression of Nact and Mef2 (orange bars) induces a much lower level of the upd ligands. Note that the y-axis is on a logarithmic scale. (B–E) An upd-LacZ reporter assay in vgGal4 wing discs validates the qPCR data and demonstrates that Nact+Src42ACA causes strong, widespread activation of upd transcription (B); in contrast, either gene alone (C, D) causes lower, more restricted levels of upd upregulation. (F–J) The 10XStatGFP reporter was used to assess JAK/STAT signal activation in vgGal4 discs grown at 18°C. Nact+Src42ACA strongly upregulates 10XStatGFP (G), whereas either gene alone (H, I) only weakly upregulates the reporter. The addition of BskDN (F) reduces the 10XStatGFP induced by Nact+Src42ACA (G) to levels similar to those of Nact alone (I). Note that since the upd-LacZ discs were grown at 25°C and the 10XSTATGFP discs were grown at 18°C, the latter displays a somewhat weaker phenotype, hence the difference in disc size between B/D and G/I. Scale bar: 100 μm.