tiRNAs & tRFs Biogenesis and Regulation of Diseases: A Review.

tiRNAs & tRFs are a class of small molecular noncoding tRNA derived from precise processing of mature or precursor tRNAs. Most tiRNAs & tRFs described originate from nucleus-encoded tRNAs, and only a few tiRNAs and tRFs have been reported. They have been suggested to play important roles in inhibiting protein synthesis, regulating gene expression, priming viral reverse transcriptases, and the modulation of DNA damage responses. However, the regulatory mechanisms and potential function of tiRNAs & tRFs remain poorly understood. This review aims to describe tiRNAs & tRFs, including their structure, biological functions and subcellular localization. The regulatory roles of tiRNAs & tRFs in translation, neurodegeneration, metabolic diseases, viral infections, and carcinogenesis are also discussed in detail. Finally, the potential applications of these noncoding tRNAs as biomarkers and gene regulators in different diseases is also highlighted.