Sequence heterogeneity at the ends of mature microRNAs (miRNAs) is well documented, but its effects on miRNA function are largely unexplored. Here we studied the impact of miRNA 5′-heterogeneity, which affects the seed region critical for target recognition. Using the example of miR-142-3p, an emerging regulator of the hematopoietic lineage in vertebrates, we show that naturally coexpressed 5′-variants (5′-isomiRs) can recognize largely distinct sets of binding sites. Despite this, both miR-142-3p isomiRs regulate exclusive and shared targets involved in actin dynamics. Thus, 5′-heterogeneity can substantially broaden and enhance regulation of one pathway. Other 5′-isomiRs, in contrast, recognize largely overlapping sets of binding sites. This is exemplified by two herpesviral 5′-isomiRs that selectively mimic one of the miR-142-3p 5′-isomiRs. We hypothesize that other cellular and viral 5′-isomiRs can similarly be grouped into those with divergent or convergent target repertoires, based on 5′-sequence features. Taken together, our results provide a detailed characterization of target recognition by miR-142-3p and its 5′-isomiR-specific viral mimic. We furthermore demonstrate that miRNA 5′-end variation leads to differential targeting and can thus broaden the target range of miRNAs.
- Kaposi's sarcoma associated herpesvirus
ASJC Scopus subject areas
- Molecular Biology