Normal expression of KCNJ11 is maintained by the G-quadruplex

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• MicroRNAs regulate gene expression by binding to target messenger RNAs (mRNAs).
• RNA G-quadruplexes are increasingly found in mRNA 3'-untranslated regions (3'-UTRs), overlapping with microRNA binding sites.

Purpose of the Study:

• To investigate the role of RNA G-quadruplex structures in mRNA 3'-UTRs on microRNA binding.
• To identify and characterize microRNA target mRNAs with potential G-quadruplex forming ability.

Main Methods:

• Bioinformatic analysis to predict G-quadruplex forming sequences in microRNA target mRNAs.
• Circular dichroism spectrometry to confirm in vitro RNA G-quadruplex formation.
• Luciferase reporter assays to assess the impact of G-quadruplex mutations on gene expression.
• Treatment with a G-quadruplex ligand (TMPyP4) to disrupt G-quadruplex structures in cardiomyocytes.

Main Results:

• Candidate G-rich sequences formed RNA G-quadruplexes in vitro.
• Mutations in critical guanosine residues disrupted G-quadruplex formation and reduced luciferase activity.
• Disruption of the KCNJ11 RNA G-quadruplex by TMPyP4 promoted microRNA binding and suppressed KCNJ11 expression in cardiomyocytes.

Conclusions:

• RNA G-quadruplex structures within mRNA 3'-UTRs directly affect microRNA binding efficiency.
• This study reveals a novel mechanism of G-quadruplex-dependent regulation of microRNA-mRNA interactions.
• This regulatory pathway is crucial for maintaining normal gene expression levels.