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Study Glial Cell Heterogeneity Influence on Axon Growth Using a New Coculture Method
Published on: September 6, 2010
Glial insulin regulates cooperative or antagonistic Golden goal/Flamingo interactions during photoreceptor axon
Hiroki Takechi1, Satoko Hakeda-Suzuki1, Yohei Nitta2,3
1Graduate School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.
Abstract:
Transmembrane protein Golden goal (Gogo) interacts with atypical cadherin Flamingo (Fmi) 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 shapes the entire organization of the visual system.
Insights
Insulin from glia regulates Golden goal (Gogo) protein phosphorylation, controlling R8 photoreceptor axon targeting in the Drosophila visual system. This stepwise signaling ensures precise wiring and layer-specific connections.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Transmembrane protein Golden goal (Gogo) is crucial for R8 photoreceptor axon guidance in the Drosophila visual system.
- The exact mechanisms controlling Gogo's function in precise R8 axon targeting remain unclear.
Purpose of the Study:
- To elucidate the regulatory mechanisms of Gogo during columnar- and layer-specific R8 axon targeting.
- To investigate the role of glial signaling in modulating Gogo function.
Main Methods:
- Investigated Gogo phosphorylation status.
- Analyzed Gogo's interaction with Flamingo (Fmi).
- Studied glial insulin secretion and its effects on Gogo.
Main Results:
- Insulin from glia alters Gogo phosphorylation, affecting its function.
- Non-phosphorylated Gogo recognizes glial protrusions for initial targeting.
- Phosphorylated Gogo, via Fmi antagonism, ensures one axon per column.
- Gogo downregulation permits vertical filopodia extension into the M3 layer.
Conclusions:
- Glia-axon signaling provides stepwise regulation of growth cone dynamics.
- This process is essential for the precise organization of the Drosophila visual system.
- Gogo phosphorylation status is a key switch for distinct targeting events.
