The Role of Noncoding mRNA Isoforms in the Regulation of Gene Expression

A majority of mammalian and human protein-coding genes undergo alternative splicing with the formation of mRNA isoforms. It was established that 30−40% of the formed mRNA isoforms fell into a special category of bifunctional molecules, “coding−noncoding RNAs.” One possible explanation for the presence of such a large number of unproductive mRNAs is that these molecules are involved in basic processes of gene expression regulation. In this review, the concept of regulated unproductive splicing and translation is considered, which implies a close relationship between the processes of alternative splicing, formation of noncoding mRNA isoforms, and their subsequent degradation, which determines the proportion of productive mRNA transcripts of a gene and the level of its expression in the cell. Modern concepts of noncoding mRNA isoforms of protein-coding genes and their role in the regulation of gene expression under certain physiological and pathophysiological conditions are presented.