Related Experiment Videos
A misexpression screen identifies genes that can modulate RAS1 pathway signaling in Drosophila melanogaster
1Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3200, USA.
Abstract:
Differentiation of the R7 photoreceptor cell is dependent on the Sevenless receptor tyrosine kinase, which activates the RAS1/mitogen-activated protein kinase signaling cascade. Kinase suppressor of Ras (KSR) functions genetically downstream of RAS1 in this signal transduction cascade. Expression of dominant-negative KSR (KDN) in the developing eye blocks RAS pathway signaling, prevents R7 cell differentiation, and causes a rough eye phenotype. To identify genes that modulate RAS signaling, we screened for genes that alter RAS1/KSR signaling efficiency when misexpressed. In this screen, we recovered three known genes, Lk6, misshapen, and Akap200. We also identified seven previously undescribed genes; one encodes a novel rel domain member of the NFAT family, and six encode novel proteins. These genes may represent new components of the RAS pathway or components of other signaling pathways that can modulate signaling by RAS. We discuss the utility of gain-of-function screens in identifying new components of signaling pathways in Drosophila.
Insights
Researchers screened for genes affecting RAS/MAPK signaling in Drosophila eye development. They identified known and novel genes, including a new NFAT family member, that modulate this crucial pathway.
Area of Science:
- Developmental Biology
- Molecular Genetics
- Signal Transduction
Background:
- R7 photoreceptor cell differentiation relies on the Sevenless receptor tyrosine kinase and the RAS/MAPK signaling cascade.
- Kinase suppressor of Ras (KSR) acts downstream of RAS1 in this pathway.
- Dominant-negative KSR expression disrupts RAS signaling, R7 differentiation, and causes developmental defects.
Purpose of the Study:
- To identify novel genes that modulate RAS/KSR signaling efficiency through gain-of-function screening.
- To discover new components of the RAS pathway or interacting signaling networks.
Main Methods:
- Conducted a gain-of-function screen in Drosophila to identify genes affecting RAS1/KSR signaling.
- Misexpressed genes in the developing eye to observe effects on RAS pathway signaling and R7 cell differentiation.
Main Results:
- Recovered three known genes (Lk6, misshapen, Akap200) that modulate RAS signaling.
- Identified seven previously undescribed genes, including a novel NFAT family member and six novel proteins.
Conclusions:
- The identified genes may represent new components of the RAS pathway or other signaling pathways that interact with RAS.
- Gain-of-function screens are effective for discovering new signaling pathway components in Drosophila.