tRNA m1A modification regulates cholesterol biosynthesis to promote antitumor immunity of CD8+ T cells.

Activation of CD8+ T cells necessitates rapid metabolic reprogramming to fulfill the substantial biosynthetic demands of effector functions. However, the posttranscriptional mechanisms underpinning this process remain obscure. The transfer RNA (tRNA) N1-methyladenine (m1A) modification, essential for tRNA stability and protein translation, has an undefined physiological function in CD8+ T cells, particularly in antitumor responses. Here, we demonstrate that the tRNA m1A "writer" gene Trmt61a enhances the tumor-killing capacity of CD8+ T cells by regulating cholesterol biosynthesis. Deletion of Trmt61a in CD8+ T cells leads to a compromised tumor-killing function in both in vivo and in vitro assays. Mechanistically, tRNA m1A promotes antitumor immunity in CD8+ T cells by enhancing the translation of ATP citrate lyase, a key enzyme for cholesterol biosynthesis. Cholesterol supplementation rescues the impaired tumor-killing function and proliferation of TRMT61A-deficient CD8+ T cells. Our findings highlight tRNA m1A modification as a regulatory checkpoint in cholesterol metabolism in CD8+ T cells, suggesting potential novel strategies for cancer immunotherapy.