New characteristics of MiRNA and IsomiR interactions with mRNA

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• MicroRNAs (miRNAs) and their variants (isomiRs) are key regulators of gene expression, playing critical roles in cellular processes and disease pathogenesis.
• Understanding miRNA/isomiR-mRNA interactions is fundamental to deciphering gene regulation, yet remains an underexplored area.

Purpose of the Study:

• To analyze the interactions between human microRNAs/isomiRs and messenger RNAs (mRNAs) using compiled chimeric read data.
• To identify the extent of isomiR-specific targeting and explore the functional implications of isomiR variations.

Main Methods:

• Compiled human chimeric reads linking miRNA/isomiR segments to mRNA segments.
• Identified and quantified microRNA/isomiR-mRNA interactions and characterized isomiRs.
• Analyzed sequence composition (A, T, C content) and binding characteristics (seed-dependent/independent, non-seed binding).

Main Results:

• Identified 1747 isomiRs and over 5 million miRNA/isomiR-mRNA interactions.
• Found that miRNAs with higher A/T and lower C content correlate with more isomiRs and mRNA targets.
• Discovered that 18.9% of mRNA targets were exclusively bound by isomiRs, suggesting unique regulatory roles.
• Observed functional divergence where isomiRs may target different mRNAs than their parent miRNAs.
• Revealed significant instances of seed-independent binding and extensive non-seed region involvement in both miRNA and isomiR interactions.

Conclusions:

• IsomiRs exhibit distinct binding patterns and can target mRNAs independently of their parent miRNAs, highlighting functional divergence.
• The study provides novel insights into the complexity and specificity of miRNA/isomiR-mediated gene regulation.
• Findings underscore the importance of considering isomiRs in understanding gene regulation, disease mechanisms, and potential therapeutic strategies.