PUSL1 (pseudouridine synthase like 1) is a mitochondrial matrix protein with tRNA pseudouridine synthase activity that catalyzes pseudouridine (Ψ) modifications at positions 38-40 of transfer RNAs 1. Through systematic knockout experiments, PUSL1 was identified as a stand-alone pseudouridine synthase with previously unknown tRNA targets, introducing Ψ modifications at distinct stages of pre-tRNA processing 1. Beyond its canonical role in tRNA modification, PUSL1 functions as a mitochondrial-related gene with broader cellular significance. It is downregulated in Kaposi's sarcoma tissues 2 and serves as a prognostic marker in diffuse large B-cell lymphoma, where it was identified among 18 mitochondrial-related genes constructing a risk stratification model 3. PUSL1 shows protein-protein interactions with BCL2L12 in hepatocellular carcinoma, where both genes function as independent risk factors for overall survival 4. In muscle regeneration models, PUSL1 expression is significantly upregulated in response to combined natural compound treatment, supporting mitochondrial stability and cellular recovery 5. Recent environmental exposure studies demonstrate that normal-range plasma mercury levels associate with altered PUSL1 expression in skin tissue, linking PUSL1 to mitochondrial oxidative phosphorylation dysfunction 6. These findings suggest PUSL1 plays critical roles in both RNA modification and mitochondrial function with potential disease implications.