Exploiting codon usage identifies intensity-specific modifiers of Ras/MAPK signaling in vivo

Area of Science:

• Molecular Biology
• Genetics
• Cell Signaling

Background:

• Signal transduction pathways, like the Ras/mitogen-activated-protein-kinase (MAPK) pathway, are crucial for biological processes and exhibit complex regulation.
• Understanding the fine-tuning of these pathways is essential for deciphering cellular functions and disease mechanisms.

Purpose of the Study:

• To explore codon usage manipulation as a novel strategy to identify context-specific regulators of signaling pathways.
• To screen the Drosophila genome for modifiers of Ras-driven eye phenotypes, distinguishing between weak and strong signaling outputs.

Main Methods:

• A forward genetic screen in Drosophila was performed using codon usage alteration to modulate Ras/MAPK signaling.
• Phenotypic analysis of Ras-driven eye development was used to identify genetic modifiers.
• Positional cloning was employed to map the genetic locus of a significant modifier.

Main Results:

• The screen identified genomic regions not previously associated with Ras phenotypic modification.
• A ribosomal protein gene, RpS21, was identified as a key modifier.
• RpS21 was shown to preferentially influence weak Ras/MAPK signaling outputs across multiple experimental contexts.

Conclusions:

• Codon usage manipulation is a viable approach for discovering novel, output-specific regulators of signaling pathways.
• RpS21 acts as an in vivo regulator of Ras/MAPK signaling, particularly impacting weaker signaling outputs.