A substrate localization model for the selective regulation of TORC1 downstream pathways

Area of Science:

• Cellular biology
• Molecular biology
• Biochemistry

Background:

• Target of rapamycin complex 1 (TORC1) is a crucial eukaryotic protein kinase complex regulating cell growth and responses to environmental conditions.
• TORC1 localization to the lysosome/vacuole is vital for its signaling functions.
• Previous research indicates TORC1's role in coordinating cellular processes.

Purpose of the Study:

• To investigate the mechanism by which oxidative stress affects TORC1 signaling in budding yeast.
• To explore the role of phosphatidylinositol 3,5-bisphosphate (PI[3,5]P2) localization in TORC1 pathway regulation.
• To determine if organelle localization of specific target proteins can independently modulate TORC1 downstream pathways.

Main Methods:

• Utilizing budding yeast as a model organism.
• Employing techniques to monitor TORC1 signaling and the localization of PI[3,5]P2 under oxidative stress conditions.
• Analyzing the impact of PI[3,5]P2 delocalization on downstream targets like Sch9.

Main Results:

• Oxidative stress selectively suppresses signaling to Sch9, an S6K-related substrate of TORC1.
• This suppression is mediated by the delocalization of PI[3,5]P2 from vacuolar membranes.
• Demonstrated a link between PI[3,5]P2 dynamics and TORC1 pathway activity.

Conclusions:

• TORC1 downstream pathways can be independently regulated by modulating the organelle localization of specific target proteins.
• The delocalization of PI[3,5]P2 represents a key mechanism for TORC1 pathway adaptation during oxidative stress.
• Findings provide insights into the intricate regulation of cellular growth and stress responses by TORC1.