Protein Prenylation Drives Discrete Signaling Programs for the Differentiation and Maintenance of Effector T Cells.

Effector regulatory T (eT) cells are essential for immune tolerance and depend upon T cell receptor (TCR) signals for generation. The immunometabolic signaling mechanisms that promote the differentiation and maintenance of eT cells remain unclear. Here, we show that isoprenoid-dependent posttranslational lipid modifications dictate eT cell accumulation and function by intersecting with TCR-induced intracellular signaling. We find that isoprenoids are essential for activated T cell suppressive activity, and T cell-specific deletion of the respective farnesylation- and geranylgeranylation-promoting enzymes Fntb or Pggt1b leads to the development of fatal autoimmunity, associated with reduced eT cell accumulation. Mechanistically, Fntb promotes eT cell maintenance by regulating mTORC1 activity and ICOS expression. In contrast, Pggt1b acts as a rheostat of TCR-dependent transcriptional programming and Rac-mediated signaling for establishment of eT cell differentiation and immune tolerance. Therefore, our results identify bidirectional metabolic signaling, specifically between immunoreceptor signaling and metabolism-mediated posttranslational lipid modifications, for the differentiation and maintenance of eT cells.