Related Experiment Video
Updated: May 24, 2026
A Reporter Assay to Analyze Intronic microRNA Maturation in Mammalian Cells
Published on: June 16, 2022
HuR protein attenuates miRNA-mediated repression by promoting miRISC dissociation from the target RNA
Pradipta Kundu1, Marc R Fabian, Nahum Sonenberg
1Friedrich Miescher Institute for Biomedical Research, PO Box 2543, 4002 Basel, Switzerland.
Abstract:
The microRNA (miRNA)-mediated repression of protein synthesis in mammalian cells is a reversible process. Target mRNAs with regulatory AU-rich elements (AREs) in their 3'-untranslated regions (3'-UTR) can be relieved of miRNA repression under cellular stress in a process involving the embryonic lethal and altered vision family ARE-binding protein HuR. The HuR-mediated derepression occurred even when AREs were positioned at a considerable distance from the miRNA sites raising questions about the mechanism of HuR action. Here, we show that the relief of miRNA-mediated repression involving HuR can be recapitulated in different in vitro systems in the absence of stress, indicating that HuR alone is sufficient to relieve the miRNA repression upon binding to RNA ARE. Using in vitro assays with purified miRISC and recombinant HuR and its mutants, we show that HuR, likely by its property to oligomerize along RNA, leads to the dissociation of miRISC from target RNA even when miRISC and HuR binding sites are positioned at a distance. Further, we demonstrate that HuR association with AREs can also inhibit miRNA-mediated deadenylation of mRNA in the Krebs-2 ascites extract, in a manner likewise depending on the potential of HuR to oligomerize.
Insights
The protein HuR can relieve microRNA (miRNA) repression of protein synthesis by binding to AU-rich elements (AREs) on messenger RNA (mRNA). HuR
Area of Science:
- Molecular Biology
- RNA Biology
- Gene Regulation
Background:
- MicroRNA (miRNA) binding to 3'-untranslated regions (3'-UTR) of messenger RNA (mRNA) represses protein synthesis.
- This repression is reversible, particularly for mRNAs with AU-rich elements (AREs).
- The protein HuR is involved in relieving miRNA repression under cellular stress.
Purpose of the Study:
- To investigate the mechanism by which HuR relieves miRNA-mediated repression.
- To determine if HuR alone is sufficient to relieve miRNA repression.
- To elucidate the role of HuR oligomerization in this process.
Main Methods:
- In vitro assays using purified miRISC (miRNA-induced silencing complex).
- Recombinant HuR and its mutants were utilized.
- Analysis of mRNA deadenylation in Krebs-2 ascites extract.
Main Results:
- HuR alone is sufficient to relieve miRNA repression in vitro, independent of cellular stress.
- HuR binding to AREs promotes the dissociation of miRISC from target mRNA, even at distant sites.
- HuR's oligomerization property is crucial for miRISC dissociation and inhibition of mRNA deadenylation.
Conclusions:
- HuR's ability to oligomerize on RNA is key to relieving miRNA-mediated repression.
- HuR can directly counteract miRNA repression by destabilizing the miRISC-mRNA interaction.
- This mechanism highlights a novel pathway for post-transcriptional gene regulation.
Related Concept Videos
01:22MicroRNAs
01:22MicroRNAs
01:22MicroRNAs
02:15Experimental RNAi
01:23RNA Interference
This process occurs naturally in cells, often through the activity of genomically-encoded microRNAs. Researchers can take advantage of this mechanism by introducing synthetic RNAs to deactivate specific genes for research or therapeutic purposes. For example, RNAi could be used...
01:23RNA Interference
This process occurs naturally in cells, often through the activity of genomically-encoded microRNAs. Researchers can take advantage of this mechanism by introducing synthetic RNAs to deactivate specific genes for research or therapeutic purposes. For example, RNAi could be used...