Resolving the Communication GAPs Upstream of TORC1

Area of Science:

• Cellular signaling pathways
• Molecular and cell biology
• Metabolic regulation

Background:

• The mechanistic target of rapamycin complex 1 (mTORC1) is a central regulator of cell growth and metabolism.
• Lysosomes act as signaling hubs integrating various cellular inputs.
• Rag GTPases are known to mediate lysosome-to-plasma membrane trafficking and nutrient sensing.

Purpose of the Study:

• To elucidate the upstream regulators of mTORC1 activity.
• To investigate the role of RAG GTPases in integrating nutrient and growth factor signals.
• To understand the mechanism by which RAG GTPases control mTORC1 localization and activation.

Main Methods:

• Biochemical assays to measure mTORC1 activity.
• Cellular imaging to track lysosome-associated protein dynamics.
• Genetic manipulation of RAG GTPase and TSC components.

Main Results:

• Nutrient and growth factor signaling converge on RAG GTPases.
• RAG GTPases modulate the residency time of the TSC complex on the lysosome membrane.
• Lysosomal localization of TSC is critical for mTORC1 activation.

Conclusions:

• RAG GTPases act as a crucial node integrating diverse cellular signals to control mTORC1.
• Lysosome-associated TSC residency is a key regulatory step in mTORC1 activation by nutrient and growth factor cues.
• This provides a molecular mechanism linking environmental cues to metabolic output via lysosomal signaling.