Nat10-mediated ac4C modification sustains macrophage proliferation and mitigates colitis progression via Mcm2 stabilization.

N4-acetylcytidine (ac4C), a form of RNA acetylation catalyzed by N-acetyltransferase 10 (Nat10), acts as a post-transcriptional regulator of RNA function. However, their role in immune cell function and ulcerative colitis (UC) remains poorly understood. Here, single-cell RNA sequencing revealed significant downregulation of Nat10 expression in macrophages from patients with UC, which was inversely correlated with disease severity. Conditional Nat10 deletion in murine macrophages impaired their proliferative capacity without affecting apoptosis, thereby exacerbating dextran sulfate sodium-induced colitis. Subsequent transcriptomic analysis revealed widespread dysregulation of cell cycle-related genes, with minichromosome maintenance complex component 2 (Mcm2) identified as a direct target of Nat10-mediated ac4C modification. Loss of Nat10 accelerated Mcm2 mRNA degradation, resulting in reduced Mcm2 protein levels, whereas overexpression of Mcm2 in Nat10-deficient macrophages restores their proliferative capacity. Moreover, Nat10-deficient macrophages exhibited a diminished ability to support intestinal epithelial cell growth and self-renewal. Collectively, this study provides the first in vivo evidence that Nat10-mediated ac4C modification sustains macrophage proliferation and attenuates colitis progression by stabilizing Mcm2 mRNA. This study uncovered a novel Nat10-ac4C-Mcm2 axis and highlighted it as a potential pathway for targeted therapeutic intervention in UC.