FIGURE 10.

Depletion of NSUN2‐mediated m5C caused a decrease in tRNA and an increase in cleaved fragments. (A) A method for tRNA charging assay. (B) tRNA charging level of indicated isodecoder family was measured. Primers specific to Leu‐CAA and Leu‐CAG were used. (C) qRT‐PCR analysis of tRNA Leu‐CAA. (D) Relationship of tRNA related RNA fragments. (E) qRT‐PCR analysis of tRNA Leu related RNA fragments. (F) Correlation scatter plot showing that tRNA expression is positively associated with m⁵C modification at variable loop. (G) Comparison between tRNA Leu‐CAA isodecoders expression and m⁵C modification. The bubble size represents the proportion of tRNA Leu‐CAA isodecoders in vector cell. (H) Comparison between tRNA expression and m⁵C modification at variable loop. Each row represents the same tRNA isodecoder. (I) The 3D structure diagram shows the position of C48 (green dot) and TΨC loop/arm (red shaded part) in tRNA Leu‐CAA‐2‐1. The blue, red, white orange and grey sphere represents the nitrogen atom (N), oxygen atom (O), hydrogen atom (H), phosphorus atom (P) and the carbon atom (C). In the secondary structure of tRNA Leu‐CAA, short red line indicates the possible cleavage sites of tRNA after methylation deletion. (J) Working model for NSUN2 mediated tRNA m⁵C modification in regulation of ATC tumourigenesis. NSUN2 sustains tRNA stability by catalysing m⁵C modification and enhances translation in cancer.