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 their effector functions. However, the post-transcriptional mechanisms underpinning this process remain obscure. The tRNA N1-methyladenine (m1A) modification, which plays a role in maintaining tRNA stability and modulating 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. We find that Trmt61a expression in CD8+ T cells is upregulated upon activation and correlates positively with T cell-mediated cytotoxicity within the tumor microenvironment of colorectal cancer (CRC) patients. Deletion of Trmt61a in CD8+ T cells leads to a compromised tumor-killing function in both in vivo and in vitro assays, which is dependent on the m1A catalytic activity of TRMT61A. Mechanistically, tRNA m1A promotes antitumor immunity in CD8+ T cells by enhancing the translation of ATP citrate lyase (ACLY), a key enzyme for cholesterol biosynthesis. Supplementation with cholesterol can rescue the impaired tumor-killing function and proliferation of TRMT61A-deficient CD8+ T cells. Our findings underscore the significance of tRNA m1A modification as a regulatory checkpoint in cholesterol metabolism in CD8+ T cells, suggesting potential novel strategies for cancer immunotherapy.