The advent of next-generation sequencing technologies has not only accelerated findings on various novel non-coding RNA (ncRNA) species but also led to the revision of the biological significance and versatility of fundamental RNA species with canonical function, such as transfer RNAs (tRNAs). Although tRNAs are best known as adapter components of translational machinery, recent studies suggest that tRNAs are not always end products but can further serve as a source for short ncRNAs. In many organisms, various tRNA-derived ncRNA species are produced from mature tRNAs or their precursor transcripts as functional molecules involved in various biological processes beyond translation. In this review, we focus on the tRNA-derived ncRNAs associated with Argonaute proteins and summarize recent studies on their conceivable biogenesis factors and on their emerging roles in gene expression regulation as regulatory RNAs.
Keywords: AGO protein; Argonaute family protein; microRNA; tRNA fragment; transfer RNA.