Association of tsRNAs with cellular senescence. (A) Cellular damage causes the release of cytochrome c from mitochondria to the cytosol, eliciting apoptosis. tiRNAs inhibit apoptosis by binding cytochrome c. The inhibition of apoptosis in damaged cells may lead to cellular senescence. (B) Activation of transposable elements can cause cellular senescence. tRFs inhibit the translation of reverse transcriptase (RTase)-encoding long-terminal repeat (LTR) retrotransposons. tRFs also inhibit the reverse transcription of LTR retrotransposons, and may prevent cellular senescence resulting from activated transposable elements.