Glutamine sensing licenses cholesterol synthesis

Area of Science:

• Biochemistry
• Cell Biology
• Metabolic Regulation

Background:

• The mevalonate pathway synthesizes essential lipids like cholesterol.
• While negative regulators are known, positive regulators of this pathway remain largely uncharacterized.
• Understanding pathway activators is crucial for metabolic control.

Purpose of the Study:

• To identify metabolites that positively regulate the mevalonate pathway.
• To elucidate the mechanism by which glutamine activates cholesterol synthesis.
• To explore therapeutic strategies for cholesterol level management.

Main Methods:

• Investigated the role of glutamine in activating the mevalonate pathway using cell culture.
• Assessed cholesterol synthesis and gene transcription under glutamine starvation.
• Utilized techniques to track SCAP/SREBP2 trafficking and rescue pathway activity.
• Examined a cell model with enhanced glutamine uptake and impaired mitochondrial respiration.

Main Results:

• Glutamine is essential for activating the mevalonate pathway and cholesterol synthesis.
• Glutamine starvation inhibits pathway transcription by disrupting ER-to-Golgi SCAP trafficking, preventing SREBP2 activation.
• Restoring SCAP/SREBP2 function or nuclear SREBP2 expression rescued pathway activity.
• Enhanced glutamine uptake correlated with increased SREBP2 activation and cholesterol levels.

Conclusions:

• The mevalonate pathway senses and is activated by glutamine via a novel mechanism involving SCAP/SREBP2 trafficking.
• Glutamine metabolism plays a critical role in regulating cholesterol biosynthesis.
• Targeting glutamine synthesis offers a potential strategy for managing cholesterol in disease states.