Kolicheski, A. | Search bioRxiv

bioRxiv2025

ACLY promotes NK cell effector function by regulating glycolysis and histone acetylation

Natural Killer (NK) cells are innate immune lymphocytes important for host viral and tumor immunity. We investigated the requirement for ATP citrate lyase (ACLY) in NK cell function using an inducible genetic mouse model. ACLY regulates the citrate-malate shuttle, generating cytosolic acetyl-coenzyme A that is primarily used for acetylation or lipid synthesis. ACLY-deficient NK cells upon IL-15 activation exhibited significant defects in glycolysis, proliferation, cytokine production, and cytotoxicity, without decreased intracellular lipids. Notably, ACLY-deficiency specifically resulted in reduced NK cell responses to activating receptors associated with the adapter proteins DAP10 or DAP12. This is due to decreased DAP12 and increased DAP10 transcript and protein, coupled with epigenetic profiling that demonstrated altered histone acetylation of these genes in ACLY KO. Supplementation of ACLY-deficient NK cells with acetate was sufficient to overcome most functional defects, including restoring DAP10/12 expression and activating receptor function, emphasizing the importance of ACLY-generated cytosolic acetyl-coenzyme A for NK effector functions.

immunology↗

bioRxiv2023

IL-15 priming alters IFN-γ regulation in murine NK cells

Natural killer (NK) effector functions can be triggered by inflammatory cytokines and engagement of activating receptors. NK cell production of IFN-{gamma}, an important immunoregulatory cytokine, exhibits activation-specific IFN-{gamma} regulation. Resting murine NK cells exhibit activation-specific metabolic requirements for IFN-{gamma} production, which are reversed for activating receptor-mediated stimulation following IL-15 priming. While both cytokine and activating receptor stimulation leads to similar IFN-{gamma} protein production, only cytokine stimulation upregulates Ifng transcript, suggesting that protein production is translationally regulated after receptor stimulation. Based on these differences in IFN-{gamma} regulation, we hypothesized that ex vivo IL-15 priming of murine NK cells allows a switch to IFN-{gamma} transcription upon activating receptor engagement. Transcriptional analysis of primed NK cells compared to naive cells or cells cultured with low-dose IL-15 demonstrated that primed cells strongly upregulated Ifng transcript following activating receptor stimulation. This was not due to chromatin accessibility changes in the Ifng locus or changes in ITAM signaling, but was associated with a distinct transcriptional signature induced by ITAM stimulation of primed compared to naive NK cells. Transcriptional analyses identified a common signature of c-Myc (Myc) targets associated with Ifng transcription. While Myc marked NK cells capable of Ifng transcription, Myc itself was not required for Ifng transcription using a genetic model of Myc deletion. This work highlights altered regulatory networks in IL-15 primed cells, resulting in distinct gene expression patterns and IFN-{gamma} regulation in response to activating receptor stimulation.

immunology↗