TRDMT1 (tRNA aspartic acid methyltransferase 1) is a highly conserved RNA methyltransferase that specifically catalyzes 5-methylcytosine (m5C) modification at cytosine 38 in the anticodon loop of tRNA(Asp), with enhanced activity on queuosine-modified tRNA(Asp) 12. Beyond tRNA, TRDMT1 methylates mRNA, promoting tRNA stability and precise protein synthesis 3. Mechanistically, TRDMT1 maintains translational fidelity; its loss compromises this function, causing misfolded protein accumulation and proteotoxic stress 4. The enzyme recognizes substrates through target recognition domain (TRD) and extension domain (TRED), with substrate preference modulated by target cytosine accessibility 5. Clinically, TRDMT1 dysfunction has significant implications for cancer therapy and inflammation. In cancer cells, TRDMT1 knockout sensitizes multiple cancer types to chemotherapy and radiotherapy through impaired unfolded protein response and increased apoptosis susceptibility 43. TRDMT1 depletion inhibits HEK293 cell proliferation and migration via altered mRNA m5C methylation 6. Conversely, in inflammation, TRDMT1 provides protective effects against LPS-induced sepsis through TLR4-NF-κB/MAPK-TNF-α pathway regulation 7. TRDMT1 knockout also restricts STING-mediated immune responses in senescent cancer cells 8. These findings position TRDMT1 as a promising therapeutic target for treating cancer, parasitic, and viral diseases 9.