2021.03.10
Glial insulin regulates cooperative or antagonistic Golden goal/Flamingo interactions during photoreceptor axon guidance
(Elife. 2021 Mar 5;10:e66718. doi: 10.7554/eLife.66718. Online ahead of print.)
Takechi H1, Hakeda-Suzuki S1, Nitta Y2,3, Ishiwata Y1, Iwanaga R1, Sato M4,5, Sugie A2,3, Suzuki T1.
1 Graduate School of Life Science and Technology, Tokyo Institute of Technology
2 Center for Transdisciplinary Research, Niigata University
3 Brain Research Institute, Niigata University
4 Mathematical Neuroscience Unit, Institute for Frontier Science Initiative, Kanazawa University
5 Laboratory of Developmental Neurobiology, Graduate School of Medical Sciences, Kanazawa University
Abstract
Transmembrane protein Golden goal (Gogo) interacts with 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. Non-phosphorylated Gogo mediates the initial recognition of the glial protrusion in the center of the medulla column, whereas phosphorylated Gogo suppresses radial filopodia extension by counteracting Flamingo to maintain a one axon to one column ratio. Later, Gogo expression ceases during the midpupal 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.
