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Analysis of corkscrew signaling in the Drosophila epidermal growth factor receptor pathway during myogenesis
M R Johnson Hamlet1, L A Perkins
1Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
Abstract:
The Drosophila nonreceptor protein tyrosine phosphatase, Corkscrew (Csw), functions positively in multiple receptor tyrosine kinase (RTK) pathways, including signaling by the epidermal growth factor receptor (EGFR). Detailed phenotypic analyses of csw mutations have revealed that Csw activity is required in many of the same developmental processes that require EGFR function. However, it is still unclear where in the signaling hierarchy Csw functions relative to other proteins whose activities are also required downstream of the receptor. To address this issue, genetic interaction experiments were performed to place csw gene activity relative to the EGFR, spitz (spi), rhomboid (rho), daughter of sevenless (DOS), kinase-suppressor of ras (ksr), ras1, D-raf, pointed (pnt), and moleskin. We followed the EGFR-dependent formation of VA2 muscle precursor cells as a sensitive assay for these genetic interaction studies. First, we established that Csw has a positive function during mesoderm development. Second, we found that tissue-specific expression of a gain-of-function csw construct rescues loss-of-function mutations in other positive signaling genes upstream of rolled (rl)/MAPK in the EGFR pathway. Third, we were able to infer levels of EGFR signaling in various mutant backgrounds during myogenesis. This work extends previous studies of Csw during Torso and Sevenless RTK signaling to include an in-depth analysis of the role of Csw in the EGFR signaling pathway.
Insights
Corkscrew (Csw) is essential for epidermal growth factor receptor (EGFR) signaling in Drosophila development. Genetic analysis reveals Csw acts upstream of MAPK, clarifying its role in RTK pathways.
Area of Science:
- Developmental Biology
- Cell Signaling
- Genetics
Background:
- Corkscrew (Csw) is a nonreceptor protein tyrosine phosphatase crucial for multiple receptor tyrosine kinase (RTK) pathways.
- Csw positively regulates signaling by the epidermal growth factor receptor (EGFR) in Drosophila.
- The precise position of Csw within the EGFR signaling hierarchy remains to be fully elucidated.
Purpose of the Study:
- To genetically position the corkscrew (csw) gene within the epidermal growth factor receptor (EGFR) signaling pathway.
- To investigate the role of Csw in mesoderm development and myogenesis.
- To extend the understanding of Csw function from Torso and Sevenless RTK signaling to the EGFR pathway.
Main Methods:
- Genetic interaction experiments were conducted in Drosophila.
- The formation of VA2 muscle precursor cells was used as an assay for EGFR-dependent signaling.
- Gain-of-function csw constructs were used to rescue loss-of-function mutations.
Main Results:
- Csw demonstrates a positive function in mesoderm development.
- Tissue-specific expression of a gain-of-function csw construct can rescue mutations in other positive signaling genes upstream of rolled (rl)/MAPK.
- EGFR signaling levels were inferred in various mutant backgrounds during myogenesis.
Conclusions:
- Csw functions positively in EGFR signaling, acting upstream of rolled (rl)/MAPK.
- This study clarifies the role of Csw in the EGFR pathway during Drosophila development.
- The findings contribute to a comprehensive understanding of RTK signaling networks.