FIGURE 2.

PI3K controls the metabolic switch to aerobic glycolysis in thymocytes but not in mature T cells. Naïve T cells take up small amounts of glucose which is for the most part metabolized to CO₂ via mitochondrial oxidative phosphorylation (OxPhos) for the efficient generation of ATP. Activated T cells and certain thymocyte subsets increase the expression of the GLUT1 glucose transporter and thus glucose uptake, and increase glycolytic flux, primarily converting glucose to lactate. This metabolic switch increases the biosynthetic capacity of the T cells and is stimulated by antigen receptor signaling (PreTCR, TCR) and maintained by certain cytokines (IL2). PI3K signaling is required for this metabolic switch during thymopoiesis but not in peripheral activated T cells.