RNA G-quadruplexes promote codon repeat-associated ribosomal frameshifting in human genes

Area of Science:

• Molecular Biology
• Genetics
• RNA Biology

Background:

• Programmed ribosomal frameshifting (PRF) is a translational recoding process.
• Previously considered rare in eukaryotes, PRF occurs extensively in humans.
• Codon repeats signal trans-frame protein production in human tissues.

Purpose of the Study:

• To elucidate the molecular mechanism of codon repeat-associated ribosomal frameshifting (CRFS).
• To identify factors enhancing PRF in human genes.

Main Methods:

• Developed a reporter system using the HDAC1 CRFS sequence for +1 frameshifting at (UAC)3 repeats.
• Performed whole-genome CRISPR screening to identify PRF enhancers.
• Investigated the role of RNA G-quadruplexes (rG4s) in PRF.

Main Results:

• Identified RBM4, an RNA-binding protein interacting with rG4s, as a PRF enhancer for HDAC1 mRNA.
• Disrupting the rG4 downstream of the (UAC)3 repeat reduced frameshifting.
• rG4-stabilizing compounds and other rG4 structures enhanced frameshifting.
• Engineered rG4 sequences significantly promoted frameshifting when inserted into other genes.

Conclusions:

• RNA G-quadruplexes (rG4s) are critical elements for CRFS.
• rG4s are significantly enriched downstream of codon repeats in the human genome.
• This rG4-mediated mechanism likely contributes to extensive ribosomal frameshifting in humans.