Glucose-dependent glycosphingolipid biosynthesis fuels CD8+ T cell function and tumor control

Glucose is essential for T cell proliferation and function, yet the metabolic fates of glucose critical for T cell responses in vivo remain poorly defined. Here, we identify glycosphingolipid (GSL) biosynthesis as an essential arm of glucose metabolism that fuels CD8+ T cell expansion and cytotoxic function in vivo. Using stable isotope tracing, we show that CD8+ effector T (Teff) cells in vivo use glucose to synthesize uridine diphosphate-glucose (UDP-Glc), a common precursor for glycogen, glycan, and GSL biosynthesis. Blocking GSL production–by targeting the enzymes UDP-Glc pyrophosphorylase 2 (UGP2) or UDP-Glc ceramide glucosyltransferase (UGCG)–blunts CD8+ T cell expansion and cytotoxic activity without impacting glucose-dependent energy production. Mechanistically, we show that glucose-dependent GSL biosynthesis (via UGCG) maintains lipid integrity at the plasma membrane and is required for lipid raft aggregation following T cell receptor (TCR) stimulation. CD8+ T cells lacking UGCG display poor cytotoxic function and reduced tumor control in vivo. Together, our data highlight GSL biosynthesis as an essential metabolic fate for glucose–independent of energy production–required to maintain membrane lipid homeostasis and CD8+ T cell cytotoxic function in vivo. RNA-seq profiling of control (NTC) and UGCG-deficient (sgUgcg) CD8+ OT-I T cells purified from spleens of Listeria (Lm-OVA)-infected mice at day 7 post-infection. 3-4 biological replicates were included per genotype (4 mice for NTC and 3 mice for sgUgcg).