ACSS2 and ACLY link nutrient-dependent chromatin accessibility to regulation of CD8 T cell effector responses

Coordination of cellular metabolism is essential for optimal T cell responses. Here, we identify cytosolic acetyl-CoA production as an essential metabolic node for CD8 T cell function in vivo. We show that acetyl-CoA derived from mitochondrial citrate via the enzyme ATP citrate lyase (Acly) is required for CD8 T cell responses to infection. However, ablation of Acly triggers an alternative, acetate-dependent pathway for acetyl-CoA production in T cells mediated by acyl-CoA synthetase short chain family member 2 (Acss2). Mechanistically, acetate fuels both the TCA cycle and cytosolic acetyl-CoA production, impacting T cell effector responses, acetate-dependent histone acetylation, and effector gene expression by altering chromatin accessibility. When Acly is functional, Acss2 is not required, suggesting acetate is not an obligate metabolic substrate for CD8 T cell function. However, deletion of Acly renders CD8 T cells dependent on acetate (via Acss2) to maintain acetyl-CoA production and effector function. Thus, together Acly and Acss2 coordinate cytosolic acetyl-CoA production in CD8 T cells to maintain chromatin accessibility and T cell effector function. CD8 T cells isolated from wild type (Acly f/f Cd4Cre-) or Acly KO (Acly f/f Cd4Cre+) mice were activated in VIM media with plate bound CD3/CD28 and IL-2 for 48 hours in the presence or absence of Acss2 inhibitor or acetate. At 48 hours post activation ATAC-sequencing was performed.