The Translational Machinery of Human CD4+ T Cells Is Poised for Activation and Controls the Switch from Quiescence to Metabolic Remodeling

Abstract

Naive Tcells respond to Tcell receptor (TCR) activation by leaving quiescence, remodeling metabolism, initiating expansion, and differentiating toward effector Tcells. The molecular mechanisms coordinating the naive to effector transition are central to the functioning of the immune system, but remain elusive. Here, we discover that Tcells fulfill this transitional process through translational control. Naive cells accumulate untranslated mRNAs encoding for glycolysis and fatty acid synthesis factors and possess a translational machinery poised for immediate protein synthesis. Upon TCR engagement, activation of the translational machinery leads to synthesis of GLUT1 protein to drive glucose entry. Subsequently, translation of ACC1 mRNA completes metabolic reprogramming toward an effector phenotype.Notably, inhibition of the eIF4F complex abrogateslymphocyte metabolic activation and differentiation, suggesting ACC1 to be a key regulatory node. Thus, our results demonstrate that translation is a direct mediator of Tcell metabolism and indicate translation factors as targets for novel immunotherapeutic approaches.