Processing by RNase 1 forms tRNA halves and distinct Y RNA fragments in the extracellular environment

In this study, we use small RNA sequencing to investigate the effect of a null mutation of RNase 1 on the levels of tRNA halves and Y RNA fragments in the extracellular environment of cultured human cells. Complemented and extended by the use of northern blots, our results demonstrate that tRNAs and Y RNAs in the vesicle-depleted extracellular compartment are released from cells as full-length precursors. Following their release, tRNAs and Y RNAs are processed by RNase 1 into distinct fragments. In addition, our findings show that standard sequencing methods employed to detect tRNA fragments leave many of such fragments undetected and that a combination of end healing, 3’ deacylation and RNA modification removal before library preparation can substantially improve detection of tRNA halves and reduce biases.