Mechanisms of action of intranuclear microRNAs. Part 1. Influence of microRNA on transcription

Abstract

The scientific review presents the mechanisms of action of intranuclear miRNAs, namely the influence of intranuclear miRNAs on transcription. To write the article, information was searched using Scopus, Web of Science, MedLine, PubMed, Google Scholar, EMBASE, Global Health, The Cochrane Library, CyberLeninka databases. The authors cite differences between nuclear and cytoplasmic functions of miRNAs. It is emphasized that the regulation of miRNA transcription is carried out mainly due to the formation of heterochromatin, and the control of translation is performed by various mechanisms. The result of microRNA action in most cases is a decrease in gene expression. However, in some cases, miRNAs can enhance gene expression activity. Intranuclear miRNAs are able to induce pretranslational silencing of protein-encoding genes, activate transcription, alter ncRNA trans­criptome, and participate in the regulation of alternative splicing. It is shown that microRNA-mediated transcriptional silencing is induced by small RNAs in the cell nucleus, which promote DNA methylation and together with Argonaute proteins are involved in chromatin modification. In microRNA-mediated transcriptional silencing, DNA methyltransferases are recruited, RNA-induced transcriptional silencing complex is formed, microRNA interacts with promoter-associated nсRNAs and DNA of target genes, and heterochromatin is formed. The authors state that the formation of heterochromatin occurs in several stages: the initiation of assembly, assembly and distribution of heterochromatin. Thus, miRNAs can act as regulators of various processes and differences between the functions and effects of miRNAs depend on their location in the nucleus or cytoplasm of the cell. MicroRNAs in the cell nucleus control transcription, in the cytoplasm — translation. The mechanism of action of intranuclear miRNAs includes induction of pretranslational silencing of protein-encoding genes, activation of transcription, alteration of ncRNA transcriptomes, participation in the regulation of alternative splicing.