Harnessing short poly(A)-binding protein-interacting peptides for the suppression of nonsense-mediated mRNA decay

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Nonsense-mediated mRNA decay (NMD) is a crucial cellular surveillance pathway that degrades aberrant messenger RNAs (mRNAs) containing premature translation termination codons (PTCs).
• NMD also plays a role in regulating the expression of normal mRNAs, particularly those with extended 3' untranslated regions (3' UTRs).
• Existing models suggest that the interaction between cytoplasmic poly(A)-binding protein 1 (PABPC1) and translation termination influences NMD, with PABPC1 near a stop codon potentially inhibiting the process.

Purpose of the Study:

• To investigate the general NMD-inhibiting property of PABPC1 using reporter mRNAs with varying NMD-inducing 3' UTRs.
• To determine if short peptides mimicking PABPC1 interactions could also inhibit NMD.
• To characterize the efficacy and positional dependence of these inhibitory peptides on NMD.

Main Methods:

• Utilized reporter mRNAs engineered with specific NMD-inducing 3' UTRs to monitor NMD activity.
• Employed short peptides containing the PABP-interacting motif 2 (PAM2) from various proteins.
• Assessed the ability of PABPC1 and PAM2 peptides to inhibit NMD triggered by long 3' UTRs, exon-junction complexes (EJCs), and individual EJC components.

Main Results:

• Demonstrated that PABPC1 generally inhibits NMD, consistent with its proposed role near translation termination.
• Showed that short PAM2 peptides, when targeted to specific positions on reporter transcripts, effectively suppress NMD.
• Confirmed that these PAM2 peptides stabilize a PTC-containing β-globin mRNA and inhibit NMD induced by long 3' UTRs and EJC components.

Conclusions:

• Established that PABPC1 possesses a general NMD-inhibiting capability.
• Identified short PABPC1-recruiting peptides (PAM2) as potent inhibitors of mammalian NMD.
• Highlighted the critical, position-dependent nature of NMD inhibition by these peptides.