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The role of the small GTPase Rap in Drosophila R7 photoreceptor specification

Yannis Emmanuel Mavromatakis1, Andrew Tomlinson

  • 1Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.

Proceedings of the National Academy of Sciences of the United States of America
|February 23, 2012
PubMed

Insights

The Drosophila R7 photoreceptor uses both Ras and Rap small GTPases for robust signaling when Notch (N) pathway activity is high. When N activity is low, only Ras is needed for mild receptor tyrosine kinase (RTK) signaling.

Area of Science:

  • Cell biology
  • Neuroscience
  • Developmental biology

Background:

  • The Drosophila R7 photoreceptor is a model for cell fate specification.
  • Receptor tyrosine kinase (RTK) and Notch (N) signaling pathways interact antagonistically to specify cell fate.
  • R7 photoreceptors require high RTK signaling to overcome strong N pathway inhibition.

Purpose of the Study:

  • To investigate the mechanisms of high-level RTK signal transduction in Drosophila R7 photoreceptors.
  • To understand how RTK signaling is modulated by the N pathway in cell fate determination.

Main Methods:

  • Utilized Drosophila R7 photoreceptor as a model system.
  • Investigated the roles of small GTPases, Ras and Rap, in RTK signal transduction.
  • Analyzed the interplay between RTK and N signaling pathways.

Main Results:

  • High RTK signal transduction in R7 photoreceptors involves both Ras and Rap small GTPases.
  • When N pathway activity is high, a robust RTK signal engages both Ras and Rap.
  • When N pathway activity is low, a mild RTK signal relies solely on Ras.

Conclusions:

  • The R7 photoreceptor employs distinct RTK signaling mechanisms depending on N pathway activity levels.
  • Both Ras and Rap GTPases are crucial for robust RTK signaling in R7 under high N conditions.
  • Ras GTPase alone is sufficient for mild RTK signaling in R7 when N activity is low.

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