5–Methylcytosine in non-communicable and communicable diseases

5-Methylcytosine (m ⁵ C) has attracted increasing attention as an important epitranscriptomic modification that regulates RNA metabolism and diverse cellular processes. It is dynamically controlled by writer, eraser, and reader proteins that govern the life cycle of the methylated transcript. Studies have demonstrated that aberrant m ⁵ C enzymatic dysregulation is linked to a wide range of human diseases, ranging from non-communicable diseases like cancer to communicable diseases like viral infections. Notably, m ⁵ C regulatory enzymes may exert context-dependent dual roles, functioning either protectively or pathogenically within and across different disease settings. However, current research efforts remain largely confined to individual disease models, and a unified understanding of m ⁵ C functions across pathologies remains lacking. Furthermore, clinical translation targeting m ⁵ C modification remains limited, with most findings restricted to experimental studies. This review aims to provide a comprehensive overview of current knowledge on m ⁵ C-mediated mechanisms across both communicable and non-communicable contexts and evaluate their potential as therapeutic targets.