| Project/Area Number |
17370077
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Developmental biology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TABATA Tetsuya The University of Tokyo, Institute of Molecular and Cellular Biosciences, Professor (10183865)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Makoto The University of Tokyo, Institute of Molecular and Cellular Biosciences, Research associate (30345235)
YOSHIDA Shoko The University of Tokyo, Institute of Molecular and Cellular Biosciences, Research associate (70372430)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥14,700,000 (Direct Cost: ¥14,700,000)
Fiscal Year 2006: ¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 2005: ¥9,100,000 (Direct Cost: ¥9,100,000)
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| Keywords | Drosophila / visual center / medulla / proneural wave / DWnt4 / Sim / JAK / STAT / Focal adhesion kinase / proneural gene / Notch / 視神経投射 / Ras / CdGAP / DFAK |
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| Research Abstract |
In Drosophila, photoreceptor cells topographically send their axons to the lamina and medulla ganglia.
We found :
1. DPP signaling mediates the maturation of the lamina glia required for the correct R axon projection pattern by controlling the expression of gcm.
2. In DWnt4 mutants, ventral retinal axons misproject to the dorsal lamina. DWnt4 is normally expressed in the ventral half of the developing lamina and DWnt4 protein was detected along ventral retinal axons. Genetic analyses on Wnt signaling components suggest direct roles of DWnt4 for retinal axon guidance.
3. R axons trigger proliferation and differentiation of lamina neurons by delivering the inductive signal, Hedgehog (Hh). We found that the bHLH-PAS transcription factor Single-minded (Sim) is induced by Hh in the lamina neurons and is required for the association of lamina neurons with R axons. In sim mutant brains, lamina neurons fail to associate with R axons. The data reveal a novel mechanism for regulation of the interaction between axons and neuronal cell bodies that establishes precise neuronal networks.
4. R axons innervate optic ganglia through the tubular structure called the optic stalk, which consists of surface glia (SG). The optic stalk is formed autonomously, independently of R axon projection. We found Fak56D, encoding a Focal adhesion kinase (FAK) and CdGAPr play an important role in forming the optic stalk.
5. Medulla neuroblasts develop sequentially in a spatially defined manner, and that lethal of scute (l(1)sc), one of the proneural genes, signals the transition of neuroepithelium to neuroblasts. L(1)sc expression is transient, progressing in a synchronized and ordered "proneural wave" that sweeps toward more lateral NE cells. L(1)sc expression is sufficient to induce NBs and is necessary for timely onset of NB differentiation. We also found that JAK/STAT signaling is activated in NE cells and negatively regulates proneural wave progression.
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