Efficient 3'-pairing renders microRNA targeting less sensitive to mRNA seed accessibility

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• MicroRNAs (miRNAs) regulate gene expression post-transcriptionally.
• miRNA target recognition primarily involves the seed region (nucleotides 2-8).
• 3 -pairing, beyond the seed region, also influences miRNA:target interactions.

Purpose of the Study:

• To investigate the combined effects of 3 -pairing and mRNA secondary structures on miRNA repression efficiency.
• To provide structural and functional evidence for 3 -pairing's role in overcoming seed-binding site inaccessibility.
• To refine predictions of effective miRNA target sites.

Main Methods:

• Selective 2 -hydroxyl acylation analyzed by primer extension (SHAPE) to study RNA structures.
• Luciferase reporter assays to measure gene repression efficiency.
• Transcriptomics analyses and high-throughput modeling of 3 -untranslated regions (3 -UTRs).

Main Results:

• 3 -pairing can compensate for inaccessible seed-binding sites, enabling miRNA-mediated repression.
• miRNA 3 -pairing can interact with mRNA sequences upstream of the seed site.
• Hairpins and bulges in target sites are tolerated, and SHAPE confirms predicted structures for effective 3 -pairing.
• Inaccessible targets like PHB2 (miR-141) can be effectively repressed through 3 -pairing.

Conclusions:

• 3 -pairing is a significant factor in miRNA target recognition, especially for sites with low seed accessibility.
• The study provides a refined model for predicting miRNA target efficacy.
• Understanding 3 -pairing enhances our knowledge of post-transcriptional gene regulation by miRNAs.