Dicer is a type III endoribonuclease and a core part of the RNA interference (RNAi) machinery. RNAi involves processing of double-stranded RNA into small precursors that can have diverse effects but typically involve a repressive effect on a target nucleic acid. We have shown previously (White et al., NSMB, 2014) that Dicer also acts in nucleus to process endogenous double stranded RNA. Transfer RNAs are 75 nt RNAs that constitute 15% of total cellular RNA. There are 500 tRNA genes (tDNAs) in the human genome, of which only 20% are unique. After initial transcription as precursors by RNA polymerase III (pol III), 50 and 30
leader sequences are removed from pre-tRNAs by RNase P and RNAse Z, respectively.
A large number of nucleobase modifications are known to occur in tRNAs some of which are thought to aid in the folding into the functional cloverleaf structure.
The present study builds on Dicer association with chromatin in human cells, focusing on Dicer occupancy of transfer RNA (tRNA) genes. Our bioinformatics analysis shows that Dicer binds to actively transcribed tRNA, most likely through dsRNA. Knockdown of Dicer does not perturb transcription of selected tDNAs, although a cryptic alternative tRNA structure is observed upon knockdown of Dicer, suggesting a role for Dicer in tRNA quality control.