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The sevenless signalling cassette mediates Drosophila EGF receptor function during epidermal development
1Zoologisches Institut, Universität Zürich, Switzerland.
Abstract:
In Drosophila, Drk, an SH2 adaptor protein, Sos, a putative activator of Ras1, Ras1, raf and rolled/MAP kinase have been shown to be required for signalling from the sevenless and the torso receptor tyrosine kinase. From these studies, it was unclear whether these components act in a single linear pathway as suggested by the genetic analysis or whether different components serve to integrate different signals. We have analyzed the effects of removing each of these components during the development of the adult epidermal structures by generating clones of homozygous mutant cells in a heterozygous background. Mutations in each of these signalling components produce a very similar set of phenotypes. These phenotypes resemble those caused by loss-of-function mutations in the Drosophila EGF receptor homolog (DER). It appears that these components form a signalling cassette, which mediates all aspects of DER signalling but that is not required for other signalling processes during epidermal development.
Insights
Drosophila
Area of Science:
- Cellular signaling pathways
- Developmental biology
- Molecular genetics
Background:
- Signaling from receptor tyrosine kinases like sevenless and torso in Drosophila involves Drk, Sos, Ras1, raf, and rolled/MAP kinase.
- Previous studies suggested a linear pathway, but integration of different signals by these components remained unclear.
Purpose of the Study:
- To investigate the roles of Drk, Sos, Ras1, raf, and rolled/MAP kinase in Drosophila epidermal development.
- To determine if these components function in a single pathway or integrate distinct signals.
Main Methods:
- Generating clones of homozygous mutant cells in a heterozygous Drosophila background.
- Analyzing the resulting phenotypes during adult epidermal development.
Main Results:
- Mutations in each signaling component produced highly similar phenotypes.
- These phenotypes mimicked those observed in loss-of-function mutations of the Drosophila EGF receptor homolog (DER).
Conclusions:
- The studied components (Drk, Sos, Ras1, raf, rolled/MAP kinase) form a signaling cassette for DER.
- This cassette mediates all aspects of DER signaling in epidermal development.
- These components are not essential for other epidermal signaling processes.