Relationship of Transfer RNAs with Epigenetic Factors and Retroelements

A hypothesis is proposed about the role of evolutionary relationship of retroelements with transfer RNAs (tRNAs) on their processing to form small non-coding RNAs. This is evidenced by the use of tRNA as primers for reverse transcriptase, origin of SINE2 from tRNA, use of LINE1 enzymes by tRNA for pseudogenes formation. Under the influence of RISC enzymes, tRFs are formed from tRNA, that control gene expression at the epigenetic level. Non-coding RNAs formed from transcripts of retroelements are characterized by similar properties. An assumption has been made about the functioning of a species-specific epigenetic network between such non-coding RNAs formed from retroelements and tRNAs. Decoding such a network may open up the possibility of creating new epigenetic agents for the treatment of human diseases, and will also allow us to determine mechanisms of genetic code emergence in evolution. One of the bases for this network formation may be the distribution and composition of tRNAs and retroelements in the genome. I have provided data on this network mechanisms formation, describing the similar functional properties of tRNAs and retroelements, their influence on the same targets and pathways in the human organism. I suppose that the relationship between tRNAs and retroelements arose as an integral property of living things when life arose in RNA world, where tRNAs were originally used to perform many regulatory catalytic functions, one of which was later transformed into the transfer of amino acids for protein synthesis.