The RING-type E3 ligase RNF186 ubiquitinates Sestrin-2 and thereby controls nutrient sensing

Area of Science:

• Cellular Biology
• Molecular Mechanisms
• Metabolic Regulation

Background:

• Nutrient sensing is vital for cellular metabolism and signaling.
• mTORC1 is a key hub for nutrient sensing, regulating anabolic processes and autophagy.
• Sestrin-2 acts as a leucine sensor and mTORC1 inhibitor, but its post-translational regulation is unclear.

Purpose of the Study:

• To investigate the post-translational regulation of Sestrin-2 via the ubiquitin proteasome system.
• To identify E3 ubiquitin ligases involved in Sestrin-2 degradation.
• To elucidate the role of RNF186 in controlling Sestrin-2 stability and mTORC1 activity.

Main Methods:

• Unbiased siRNA screening of ubiquitin E3 ligases.
• Co-immunoprecipitation to assess protein interactions.
• Western blotting to analyze protein levels and ubiquitination.
• RNF186 knockdown experiments.

Main Results:

• RNF186 was identified as an E3 ligase mediating Sestrin-2 ubiquitination and degradation.
• RNF186 and Sestrin-2 interact via distinct C-terminal motifs, with Lys-13 as a potential ubiquitination site.
• RNF186 knockdown led to increased Sestrin-2 levels and reduced mTORC1 activation.

Conclusions:

• A novel regulatory axis involving RNF186 and Sestrin-2 controls mTORC1 activity.
• RNF186-mediated degradation of Sestrin-2 is a key post-translational regulatory mechanism.
• Inhibiting RNF186 could be a therapeutic strategy to enhance Sestrin-2 levels and modulate mTORC1 signaling.