Mechanisms of action of intranuclear microRNAs. Part 2. MicroRNA-mediated regulation of ncRNA transcriptome and alternative splicing

Abstract

The scientific review presents the mechanisms of action of intranuclear miRNAs, namely microRNA-mediated regulation of the non-coding RNA (ncRNA) transcriptome and alternative splicing. To write the article, information was searched using Scopus, Web of Science, MedLine, PubMed, Google Scholar, EMBASE, Global Health, The Cochrane Library, CyberLeninka databases. It is emphasized that a significant effect on the composition of the transcriptome is provided by microRNAs in the RNA-induced silencing complex that induce posttranscriptional degradation of long ncRNAs localized in the cell nucleus. Scientists believe that long ncRNAs are involved in the epigenetic regulation of gene silencing through chromatin remodeling. It is shown that long ncRNAs are actively involved in the development of some liver diseases. It is reported that the most important mechanism for expanding the spectrum of the transcriptome in the cell is the alternative splicing of pre-mRNA. The authors present the results of scientific studies that show that pre-mRNA of more than 90 % of human genes are subjected to alternative splicing. It is presented that splicing is performed by a specialized macromolecular formation — suprasplicesome, which is a megacomplex (21 MDA) of nuclear ribonucleroprotein. It is shown that scientists have proposed two models of epigenetic regulation of splicing: kinetic and recruitment one. The authors reveal the main provisions of these models. MicroRNAs are actively involved in splicing. Liver disease may be based on a deficiency of splicing factors and deregulation of alternative splicing caused by the action of miRNAs. Disorders of alternative splicing, which stimulate proliferation, prevent apoptosis and support cell transformation, are a pathognomonic phenomenon in malignant tumors. Thus, the constituent mechanisms of action of intranuclear miRNAs are alteration of the ncRNAs transcriptome and participation in the regulation of alternative splicing. MicroRNA-mediated regulation of the stability of long ncRNAs causes a change in the spectrum of activity of expression of epigenetically regulated genes. Long ncRNAs are actively involved in the development of some liver diseases. Alternative splicing is an integral part of cell differentiation and contributes to the formation of tissue specificity. Alternative splicing and generation of various isoforms of proteins determine molecular consequences that cause the development of various pathological conditions.