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Preparation of Adult Drosophila Eyes for Thin Sectioning and Microscopic Analysis
Published on: August 27, 2011
Extracellular signals responsible for spatially regulated proliferation in the differentiating Drosophila eye
Lucy C Firth1, Nicholas E Baker
1Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
Abstract:
Spatially and temporally choreographed cell cycles accompany the differentiation of the Drosophila retina. The extracellular signals that control these patterns have been identified through mosaic analysis of mutations in signal transduction pathways. All cells arrest in G1 prior to the start of neurogenesis. Arrest depends on Dpp and Hh, acting redundantly. Most cells then go through a synchronous round of cell division before fate specification and terminal cell cycle exit. Cell cycle entry is induced by Notch signaling and opposed in subsets of cells by EGF receptor activity. Unusually, Cyclin E levels are not limiting for retinal cell cycles. Rbf/E2F and the Cyclin E antagonist Dacapo are important, however. All retinal cells, including the postmitotic photoreceptor neurons, continue dividing when rbf and dacapo are mutated simultaneously. These studies identify the specific extracellular signals that pattern the retinal cell cycles and show how differentiation can be uncoupled from cell cycle exit.
Insights
Extracellular signals like Dpp and Hh orchestrate Drosophila retinal cell cycles, with Notch signaling inducing entry and EGF receptor activity opposing it. Mutations reveal Rbf/E2F and Dacapo control cell division timing during differentiation.
Area of Science:
- Developmental biology
- Cell cycle regulation
- Neuroscience
Background:
- Cell differentiation in the Drosophila retina involves precisely timed cell cycles.
- Extracellular signals play a crucial role in patterning these cell cycles.
Purpose of the Study:
- To identify extracellular signals controlling Drosophila retinal cell cycle patterns.
- To understand the interplay between cell cycle regulation and differentiation.
Main Methods:
- Mosaic analysis of signal transduction pathway mutations.
- Investigation of cell cycle regulators like Cyclin E, Rbf/E2F, and Dacapo.
Main Results:
- Dpp and Hh redundantly regulate G1 arrest before neurogenesis.
- Notch signaling induces cell cycle entry, opposed by EGF receptor activity.
- Rbf/E2F and Dacapo are critical for timely cell cycle exit, even in postmitotic cells.
Conclusions:
- Specific extracellular signals pattern Drosophila retinal cell cycles.
- Differentiation can be uncoupled from terminal cell cycle exit.
