Pyruvate dehydrogenase complex integrates the metabolome and epigenome in memory T cell differentiation in vitro

BACKGROUND: Modulation of metabolic flux through pyruvate dehydrogenase complex (PDC) plays an important role in T cell activation and differentiation. PDC sits at the transition between glycolysis and the tricarboxylic acid cycle and is a major producer of acetyl-CoA, marking it as a potential metabolic and epigenetic node. METHODS: To understand the role of pyruvate dehydrogenase complex in T cell differentiation, we generated mice deficient in T cell pyruvate dehydrogenase E1A (Pdha) subunit using a CD4-cre recombinase-based strategy. To control for the contribution of exogenous metabolites in vivo, we conducted our T cell functional studies in vitro. T cells were differentiated into memory and effector T cells using standardized protocols. Cells were analyzed using stable isotopic tracing studies, metabolomics, RNAseq, ATACseq, ChIPseq and histone proteomics. RESULTS: Herein, we show that genetic ablation of PDC activity in T cells (TPdh(−/−)) leads to marked perturbations in glycolysis, the tricarboxylic acid cycle, and OXPHOS. Due to depressed OXPHOS, TPdh(−/−)T cells became dependent upon substrate level phosphorylation via glycolysis. Due to the block of PDC activity, histone acetylation was reduced, as were most other types of post translational modifications. Transcriptional and functional profiling revealed abnormal CD8(+) memory T cell differentiation in vitro. CONCLUSIONS: Collectively, our data indicate that PDC integrates the metabolome and epigenome in memory T cell differentiation. Targeting this metabolic and epigenetic node can have widespread ramifications on cellular function.