Predictable suppression of gene expression by 5'-UTR-based RNA quadruplexes

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• Four-stranded DNA and RNA quadruplexes (G4 motifs) are non-B DNA conformations with suspected in vivo roles.
• Bioinformatics suggests G4 motifs in promoter regions may regulate transcription, but experimental evidence is limited.
• Unlike DNA G4 motifs, RNA G4 motifs lack complementary strand interference, suggesting a stronger role in gene expression regulation.

Purpose of the Study:

• To investigate the structure-function relationship of synthetic G4 motifs in 5'-UTRs.
• To establish the effect of G4 motifs on gene expression at the translational level.
• To determine how specific G4 motif features influence gene expression suppression.

Main Methods:

• Utilized bioinformatics to identify putative DNA G-quadruplexes.
• Experimentally analyzed synthetic G4 sequences in 5'-UTRs across multiple mammalian cell lines.
• Assessed the impact of G4 motif features (loop-length, GGG-repeats) on gene expression.

Main Results:

• Demonstrated a universal 'translational suppressor' effect of G4 motifs on gene expression.
• Showed that specific structural features, such as loop length and number of GGG-repeats, modulate the suppressive impact.
• Observed consistent and predictable gene expression repression by naturally occurring RNA G4 motifs.

Conclusions:

• RNA G4 motifs function as translational suppressors, impacting gene expression.
• The structural characteristics of G4 motifs are critical determinants of their regulatory function.
• These findings highlight the functional relevance of RNA G4 motifs in gene regulation.