TY - JOUR T1 - Glial insulin regulates cooperative or antagonistic Golden goal/Flamingo interactions during photoreceptor axon navigation JF - bioRxiv DO - 10.1101/2020.01.23.916403 SP - 2020.01.23.916403 AU - Hiroki Takechi AU - Satoko Hakeda-Suzuki AU - Yohei Nitta AU - Yuichi Ishiwata AU - Makoto Sato AU - Atsushi Sugie AU - Takashi Suzuki Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/01/24/2020.01.23.916403.abstract N2 - Transmembrane protein Golden goal (Gogo) interacts with the atypical cadherin Flamingo to direct R8 photoreceptor axons in the Drosophila visual system. However, the precise mechanisms underlying Gogo regulation during columnar- and layer-specific R8 axon targeting are unknown. Our studies demonstrated that the insulin secreted from surface and cortex glia switches the phosphorylation status of Gogo, thereby regulating its two distinct functions in this process. Nonphosphorylated Gogo mediates the initial recognition of the glial protrusion in the center of the medulla column, whereas phosphorylated Gogo suppresses horizontal filopodia extension by counteracting Flamingo to maintain one axon to one column ratio. Later, Gogo expression ceases during the midpupal developmental stage, thus allowing R8 filopodia to extend vertically into the M3 layer. These results demonstrate that the long- and short-range signaling between the glia and R8 axon growth cones regulates growth cone dynamics in a stepwise manner, and thus shape the entire organization of the visual system’s functional neuronal circuit. ER -