TRMT10C is a mitochondrial tRNA N(1)-methyltransferase and a component of mitochondrial ribonuclease P, a three-protein complex that processes precursor tRNAs. As part of the MRPP1-MRPP2 subcomplex (TRMT10C paired with HSD17B10), it catalyzes N(1)-methylation of guanine and adenine at position 9 (m1G9 and m1A9) in tRNAs and acts as a tRNA maturation platform that enhances 3'-end processing and coordinates with downstream maturation enzymes 1. Beyond tRNA, TRMT10C also methylates MT-ND5 mRNA. In disease contexts, TRMT10C dysfunction associates with mitochondrial disorders affecting oxidative phosphorylation; recent evidence indicates that compromised TRMT10C activity impairs RNA processing and energy production 2. In nonalcoholic fatty liver disease, exosome-derived TRMT10C translocates to adipocyte mitochondria where it inhibits ND5 and ND6 translation, increasing reactive oxygen species and promoting breast cancer progression in susceptible individuals 3. Pathogenic mechanisms also involve aberrant nuclear localization of TRMT10C, which mediates m1A-driven mRNA decay linked to inflammation and oxidative stress in cardiac injury 4. These findings position TRMT10C as a critical regulator of mitochondrial biogenesis with implications for metabolic disease and cancer.