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3' Uridylation Confers miRNAs with Non-canonical Target Repertoires
Acong Yang1, Xavier Bofill-De Ros1, Tie-Juan Shao2
1RNA Mediated Gene Regulation Section, RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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.
Insights
Post-maturation modifications of microRNAs (miRNAs), like 3' uridylation, can alter their function. Uridylation enables tail-U-mediated repression (TUMR), expanding miRNA targets and regulating non-canonical targets.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- MicroRNAs (miRNAs) regulate gene expression through sequence complementarity.
- Numerous miRNA isoforms (isomiRs) exist, often modified post-maturation, particularly via 3' uridylation.
- The functional impact of these sequence modifications on miRNA activity is largely unknown.
Purpose of the Study:
- To investigate how 3' uridylation affects miRNA function and target recognition.
- To elucidate the mechanism of tail-U-mediated repression (TUMR).
- To identify non-canonical miRNA targets regulated by uridylated miRNAs.
Main Methods:
- Utilized human miR-27a as a model system in cell lines.
- Assessed target site function based on base-pairing with miRNA seed sequences.
- Investigated the role of uridylation enzymes TUT4 and TUT7.
- Identified uridylated miR-27a-specific targets in human cells.
Main Results:
- Discovered that 3' uridylation can restore function to non-canonical target sites via tail-U-mediated repression (TUMR).
- Demonstrated that TUMR is dependent on uridylation enzymes TUT4 and TUT7.
- Identified novel non-canonical targets regulated specifically by uridylated miR-27a.
- Provided evidence that TUMR expands the regulatory scope of other endogenous miRNAs.
Conclusions:
- 3' uridylation is a key mechanism that modulates miRNA function by altering target recognition.
- Tail-U-mediated repression (TUMR) expands the repertoire of miRNA targets, including non-canonical ones.
- Uridylated isomiRs play a significant role in gene regulation by targeting non-canonical sites.