Hints of tRNA-Derived Small RNAs Role in RNA Silencing Mechanisms

Abstract

With the advent of new and improved high-throughput sequencing technologies in the last few years, a growing number of novel classes of small RNA, other than miRNAs or siRNA, has emerged, which appear as new actors in gene expression regulation. tRNA-derived small RNAs represent one of these novel members that are, surprisingly, among the most conserved class of small RNAs throughout evolution. They could represent the most primitive small RNA pathways from which the well-known canonical RNA silencing pathways reported in higher eukaryotes evolved. This review aims to make a compilation of the most relevant research literature in this field with the purpose of shedding light on the relation of these primitive tRNA-derived molecules with the gene silencing machinery.

Identification of two novel functional tRNA-derived fragments induced in response to respiratory syncytial virus infection

“…In addition to their fragmentation patterns as discussed, we found tRFs have gene silencing functions. The gene silencing functions of tRFs are consistent with studies showing some tRFs being bound to Argonaute/Piwi proteins, well-known components of the RNA-induced silencing complex [30][31][32][33][34][35]. In this study, we are particularly interested in the role of tRFs in the replication of RSV and the associated host response, as the pulmonary RSV load is correlated to the disease severity [36][37][38].…”

An overview of microRNAs

“…While the aforementioned RNAs are mature miRNAs that are generated through non-canonical routes, there are other classes of small RNAs that are not miRNAs, yet are produced by Drosha and/or Dicer activity and bound to RISC[88]. The best characterized class of these RNAs is the tRNA derived small RNA fragments (tRF or tsRNAs).…”

Slicing tRNAs to boost functional ncRNA diversity

“…Here no correlation between targeted tRNAs and their number of genes, their cellular copy number, or the codon usage, has been found. [43][44][45] Since there is no obvious consistency with respect to the preferred isoacceptors targeted for tRNA halves production in different organisms, this process seems to be species-specific. However, in both cleavage scenarios, the stability of the two generated tRNA halves can be asymmetric and change within the same organism, depending on the encountered stress condition and life stage.…”