Early methionine availability attenuates T cell exhaustion

Area of Science:

• Immunology
• Metabolic pathways
• Cell signaling

Background:

• T-cell receptor (TCR) activation is crucial for adaptive immunity.
• Nutrient availability, such as methionine (Met), can influence immune cell function.
• Early events in T-cell activation dictate long-term cell fate and function.

Purpose of the Study:

• To investigate the interplay between methionine availability and TCR signaling during early T-cell activation.
• To determine the impact of early metabolic conditions on subsequent T-cell fate, including T-cell exhaustion.
• To identify molecular mechanisms linking nutrient availability to T-cell activation pathways.

Main Methods:

• Investigated T-cell activation in the presence of varying methionine concentrations.
• Analyzed calcium (Ca2+) influx, NFAT1 activation, and promoter occupancy.
• Examined changes in the protein arginine methylome, focusing on KCa3.1 methylation.
• Assessed T-cell function in mouse tumor and infection models.

Main Results:

• Limiting methionine during the initial 30 minutes of TCR engagement increased Ca2+ influx and NFAT1 activation, leading to T-cell exhaustion.
• Identified arginine methylation of KCa3.1 as a key regulator of Ca2+-mediated NFAT1 signaling.
• Ablation of KCa3.1 arginine methylation resulted in increased NFAT1 nuclear localization and dysfunctional T-cells.
• Early methionine supplementation reduced nuclear NFAT1 in tumor-infiltrating T-cells and enhanced antitumor activity.

Conclusions:

• Early methionine availability critically regulates T-cell activation and fate.
• Methionine-dependent KCa3.1 methylation is a novel mechanism controlling T-cell signaling and function.
• Targeting early methionine metabolism holds potential for augmenting anti-tumor immunity.