IsomiR expression patterns in canonical and Dicer-independent microRNAs

Multiple microRNA (miRNA) variants, known as isomiRs, are extensively distributed in miRNA loci and predominantly derive from the alternative cleavage of Drosha/Dicer and 3′addition events. The present study aimed to investigate the expression patterns of multiple isomiRs in typical miRNA and Dicer-independent miRNA loci by conducting evolutionary and expression analysis using public datasets. Although different miRNA maturation processes exist, multiple isomiRs can be detected by similar expression distributions. However, isomiR expression in Dicer-independent miRNA loci tends to be at a moderate level, particularly for random distribution in the ends that are split by Dicer in the typical miRNA loci. Compared with the mature miRNA locus (dominant miRNA locus), the non-dominant miRNA locus indicates an expression distribution similar to that of the Dicer-independent miRNA locus. These results increase the understanding of multiple isomiRs in the progression of diseases.