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Updated: Aug 14, 2026
Live-imaging of the Drosophila Pupal Eye
Published on: January 12, 2015
Notch activation of yan expression is antagonized by RTK/pointed signaling in the Drosophila eye
Margaret Rohrbaugh1, Edward Ramos, Duc Nguyen
1Department of Biochemistry and Molecular Biology, University Park, PA 16802, USA.
Abstract:
Receptor tyrosine kinase (RTK) signaling plays an instructive role in cell fate decisions, whereas Notch signaling is often involved in restricting cellular competence for differentiation. Genetic interactions between these two evolutionarily conserved pathways have been extensively documented. The underlying molecular mechanisms, however, are not well understood. Here, we show that Yan, an Ets transcriptional repressor that blocks cellular potential for specification and differentiation, is a target of Notch signaling during Drosophila eye development. The Suppressor of Hairless (Su[H]) protein of the Notch pathway is required for activating yan expression, and Su(H) binds directly to an eye-specific yan enhancer in vitro. In contrast, yan expression is repressed by Pointed (Pnt), which is a key component of the RTK pathway. Pnt binds specifically to the yan enhancer and competes with Su(H) for DNA binding. This competition illustrates a potential mechanism for RTK and Notch signals to oppose each other. Thus, yan serves as a common target of Notch/Su(H) and RTK/Pointed signaling pathways during cell fate specification.
Insights
Notch and Receptor Tyrosine Kinase (RTK) signaling pathways use the Yan gene to control cell fate. Yan acts as a common target, with Notch activating it and RTK repressing it via competing transcription factors.
Area of Science:
- Developmental biology
- Molecular genetics
- Cell signaling
Background:
- Receptor tyrosine kinase (RTK) and Notch signaling pathways regulate cell fate decisions.
- While genetic interactions are known, molecular mechanisms of RTK-Notch interplay remain unclear.
- Yan, an Ets transcriptional repressor, inhibits cell specification and differentiation.
Purpose of the Study:
- To elucidate the molecular mechanisms by which RTK and Notch signaling pathways interact.
- To investigate the role of Yan as a target in Drosophila eye development.
- To understand how Yan integrates opposing signals from RTK and Notch pathways.
Main Methods:
- Analysis of gene expression in Drosophila eye development.
- Identification of transcription factor binding sites on the yan enhancer.
- In vitro DNA binding assays for Suppressor of Hairless (Su[H]) and Pointed (Pnt).
Main Results:
- Yan is a direct transcriptional target of Notch signaling via Suppressor of Hairless (Su[H]).
- Yan expression is repressed by the RTK pathway component Pointed (Pnt).
- Su(H) and Pnt compete for binding to the yan enhancer, demonstrating opposing pathway regulation.
Conclusions:
- Yan acts as a crucial integrator of opposing Notch and RTK signaling pathways.
- The competition between Su(H) and Pnt on the yan enhancer provides a molecular mechanism for signal antagonism.
- This study reveals how Yan mediates cell fate decisions by responding to distinct signaling inputs.
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