Abstract
Many microRNAs (miRNAs) exist alongside abundant miRNA isoforms (isomiRs), most of which arise from post-maturation sequence modifications such as 3′ uridylation. However, the ways in which these sequence modifications affect miRNA function remain poorly understood. Here, using human miR-27a in cell lines as a model, we discovered that a nonfunctional target site unable to base-pair extensively with the miRNA seed sequence can regain function when an upstream adenosine is able to base-pair with a post-transcriptionally added uridine in the miR-27a tail. This tail-U-mediated repression (TUMR) is abolished in cells lacking the uridylation enzymes TUT4 and TUT7, indicating that uridylation alters miRNA function by modulating target recognition. We identified a set of non-canonical targets in human cells that are specifically regulated by uridylated miR-27a. We provide evidence that TUMR expands the targets of other endogenous miRNAs. Our study reveals a function of uridylated isomiRs in regulating non-canonical miRNA targets. Yang et al. demonstrate that mRNAs lacking a seed pairing are repressed by miR-27a because of base-pairing between an upstream adenosine in the target and a non-templated U tail in miR-27a. They identify a large class of non-canonical targets regulated by uridylated miRNAs and reveal a novel function of 3′ isomiRs.
| Original language | English |
|---|---|
| Journal | Molecular Cell |
| Volume | 75 |
| Issue | 3 |
| Pages (from-to) | 511-522.e4 |
| ISSN | 1097-2765 |
| DOIs | |
| Publication status | Published - 8 Aug 2019 |
| Externally published | Yes |
Keywords
- isomiRs
- miR-27a
- miRNA
- noncanonical target
- uridylation