A hypoxia-responsive tRNA-derived small RNA confers renal protection via RNA autophagy
Emerging studies have revealed diverse cellular functions of tRNA-derived small RNAs (tsRNAs, or tDRs). Here, we show that a hypoxia-induced tDR, derived from the 3' end of tRNA-Asp-GTC (tRNA-Asp-GTC-3'tDR), activates, while its inhibition blocks autophagic flux in kidney cells. Functional gain/loss-of-function studies in murine kidney disease models demonstrate a significant reno-protective function of tRNA-Asp-GTC-3'tDR. Mechanistically, tRNA-Asp-GTC-3'tDR assembles stable G-quadruplex structures and sequesters pseudouridine synthase PUS7, preventing catalytic pseudouridylation of histone mRNAs. The resulting pseudouridylation deficiency directs histone mRNAs to the autophagosome-lysosome pathway, triggering RNA autophagy. We confirm this tDR-induced RNA autophagy pathway in murine and human kidney diseases. Together, our findings identify a novel role for tRNA-Asp-GTC-3'tDR in regulating RNA autophagy in kidney cells to maintain homeostasis and protect against kidney injury. Overall design: Long RNA-seq profiling HEK cells transfected with a 3' tRNA-Asp tDR or scrambled control.