Abstract
Transfer RNA-derived small RNAs (tDRs) are emerging regulators of cellular stress response, yet their biogenesis and activities during mitochondrial dysfunction remain poorly understood. Here we profiled tDRs generated in HEK293T cells exposed to inhibitors of respiratory complexes I-V (rotenone, TTFA, antimycin A, KCN, oligomycin) or to arsenite and assessed the impact of CRISPR-mediated angiogenin (ANG) knockout, ANG over-expression and recombinant ANG supplementation on the stress response and tDRs production. tDR-seq revealed stress-specific, highly ordered tDR repertoires: rotenone and antimycin predominantly induced internal (i-tRF) and 3' tRNA (tRF3) fragments, whereas arsenite induced anticodon-cleaved tRNA halves (tiRNAs). mito-tDRs were mostly internal fragments and antimycin induced the strongest mitochondrial tDRs expression. ANG deletion markedly impaired stress-induced tDR biogenesis and sensitized cells to antimycin and oligomycin stress, whereas its overexpression selectively enhanced tDR biogenesis and conferred protection against these mitochondrial stressor. Synthetic tDR mimics failed to rescue viability, implying that native modification patterns or cooperative tDR pools are required. tDR motif enrichment analysis identified YBX1-binding sites among antimycin-induced tDRs, and genetic perturbation of YBX1 phenocopied aspects of enhanced mitochondrial bioenergetics and stress resistance. Together, these findings demonstrate that context-specific, ANG-directed tDR biogenesis forms a crucial arm of the mitochondrial stress response.