AMPKα regulates glycolytic reprogramming to sustain NK cell proliferation and effector function

Abstract Natural killer (NK) cells are critical innate lymphocytes that mediate early anti-viral immunity through cytotoxicity and cytokine production. Activation of NK cells require metabolic reprogramming to sustain proliferation and effector functions; however, the molecular regulators coordinating this process remain incompletely defined. AMP-activated protein kinase (AMPK) is classically viewed as a cellular energy sensor activated under metabolic stress, yet its role in NK cell biology is not fully understood. Here, using Cre-inducible genetic ablation of AMPKα in NK cells, we show that AMPK signaling is dispensable for NK cell development but contributes to optimal metabolic fitness, proliferative expansion, and effector function. Notably, AMPKα deficiency impaired NK cell response even under nutrient-replete conditions. Mechanistically, loss of AMPKα disrupted glycolytic reprogramming upon activation, limiting the acquisition of aerobic glycolysis required to sustain proliferation. This impaired metabolic capacity rendered NK cells more vulnerable to mitochondrial stress and compromised cellular fitness. AMPKα-deficient NK cells also exhibited diminished CD25 upregulation and reduced expression of key glycolytic genes, as supported by transcriptomic analysis, indicating altered metabolic activation at both functional and transcriptional levels. In vivo, AMPKα-deficient NK cells showed reduced expansion and impaired anti-viral responses during murine cytomegalovirus infection. Collectively, our findings identify AMPKα as an important regulator of NK cell metabolism and survival and suggest that it contributes to the coordination of metabolic reprogramming and effector responses during anti-viral immunity. These results provide insight into how metabolic pathways shape immune cell fitness in infectious and inflammatory settings.