EGO complex at 20: The Rag GTPase-TORC1 nutrient-sensing blueprint

Area of Science:

• Cellular Biology
• Molecular Biology
• Biochemistry

Background:

• Nutrient signaling pathways regulate cellular growth and metabolism.
• The target of rapamycin complex 1 (TORC1) is a crucial regulator of cell growth.
• The precise mechanisms by which amino acids regulate TORC1 remained largely unknown.

Purpose of the Study:

• To elucidate the molecular mechanisms connecting amino acid availability to TORC1 activation.
• To identify the key components involved in nutrient sensing and TORC1 regulation.
• To establish a conserved framework for nutrient-TORC1 coupling across different species.

Main Methods:

• Utilized Saccharomyces cerevisiae (yeast) as a model organism.
• Investigated the role of the EGO complex and Rag GTPases in nutrient signaling.
• Cross-species comparative analysis in flies and mammals.

Main Results:

• Identified the EGO complex as a crucial link between Rag GTPases and TORC1 reactivation.
• Demonstrated glutamine as a key metabolite in nutrient sensing.
• Revealed a conserved mechanism where Rag GTPases integrate amino acid signals for spatial TORC1 control at membranes.
• Discovered the role of scaffolds, GAP complexes, and nutrient sensors in regulating Rag GTPase activity.

Conclusions:

• Early yeast research provided foundational insights into nutrient-TORC1 coupling.
• A conserved cross-species framework for nutrient-TORC1 signaling has been established.
• Understanding this pathway has broad implications for physiology, disease, and therapeutic strategies.