How miRNA Structure of Animals Influences Their Biogenesis

MicroRNAs are small noncoding RNAs that are involved in the post-transcriptional regulation of the gene expression in various organisms. This article reviews recent advances in understanding the role of the primary and secondary structures of animal miRNA precursors through the biogenesis stages and the miRNA maturation steps. Also, we describe the effects of genetic variability and heterogeneity of miRNA ends, which play an important role in epitranscriptomics as well as annotation errors in the miRNA databases.