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Multiple functions of the EGF receptor in Drosophila eye development
M Domínguez1, J D Wasserman, M Freeman
1MRC Laboratory of Molecular Biology, Cambridge, UK.
Background:
During animal development, cells need to make spatially and temporally regulated fate decisions. These decisions are largely controlled by intercellular signalling, often through receptor tyrosine kinases. One of these, the epidermal growth factor receptor (EGFR), regulates multiple cell fate decisions. Its importance in the recruitment of photoreceptors in the developing fly eye, a useful model for neural development, has already been reported. Other EGFR functions in the eye have not been characterised.
Results:
We have examined the consequences of removing or activating the EGFR at different stages of eye development. The earliest stages of assembly occurred normally within EGFR- clones--the morphogenetic furrow was unimpeded and the R8 photoreceptor was specified. All subsequent photoreceptor recruitment was blocked. EGFR- clones had a characteristic shape indicating that they had undergone substantial cell death posterior to the furrow, where the differentiation program is normally activated; consistent with this, excess apoptosis was detected. We found that the receptor also regulates cell proliferation in the disc, has an early function at the disc margin (where the morphogenetic furrow initiates) and contributes to the regulation of spacing of the R8 precursors. Finally, we found that activation of the receptor is sufficient to trigger non-R8 photoreceptor development, even in cells in front of the furrow or in the absence of the proneural gene atonal.
Conclusion:
At least five distinct functions of EGFR signalling need to be integrated during fly eye development. These include roles in cell proliferation, survival and differentiation.
Insights
Epidermal growth factor receptor (EGFR) signaling is crucial for fly eye development, controlling photoreceptor recruitment, cell proliferation, survival, and differentiation. Its absence blocks development, while activation can trigger non-photoreceptor cell fates.
Area of Science:
- Developmental Biology
- Cell Signaling
- Neuroscience
Background:
- Cell fate decisions during development are regulated by intercellular signaling pathways.
- Receptor tyrosine kinases, like epidermal growth factor receptor (EGFR), play key roles in these signaling processes.
- EGFR is known to influence photoreceptor recruitment in developing fly eyes, but other functions remain uncharacterized.
Purpose of the Study:
- To investigate the multifaceted roles of EGFR signaling in the developing fly eye.
- To characterize the consequences of EGFR absence or activation at various developmental stages.
Main Methods:
- Genetic manipulation of EGFR expression (removal or activation) in developing fly eyes.
- Analysis of developmental stages, including morphogenetic furrow progression, photoreceptor specification, and cell death.
- Observation of cell proliferation and precursor spacing.
Main Results:
- EGFR absence blocked photoreceptor recruitment after R8 specification and led to increased apoptosis.
- EGFR regulates cell proliferation, has an early role at the disc margin, and influences R8 precursor spacing.
- EGFR activation induced non-R8 photoreceptor development independently of proneural genes.
Conclusions:
- EGFR signaling has at least five distinct functions in fly eye development.
- These functions include critical roles in cell proliferation, survival, and differentiation.
- Understanding EGFR's complex roles is essential for comprehending neural development.