uORF-targeting steric block antisense oligonucleotides do not reproducibly increase RNASEH1 expression.

Area of Science:

• Molecular Biology
• Gene Regulation
• Antisense Oligonucleotide Therapeutics

Background:

• Upstream open reading frames (uORFs) are cis-regulatory elements in 5' UTRs that typically repress downstream protein-coding gene expression.
• Antisense oligonucleotides (ASOs) have been proposed as a therapeutic strategy to modulate gene expression by targeting specific RNA sequences.

Purpose of the Study:

• To re-evaluate the efficacy of previously reported steric block antisense oligonucleotides (ASOs) designed to target the RNASEH1 uORF.
• To determine if these ASOs can upregulate RNASEH1 protein expression by disrupting uORF-mediated translational repression.

Main Methods:

• Re-synthesis of three potent steric block ASOs targeting the RNASEH1 uORF.
• Replication of experimental conditions from a previous study.
• Testing ASO efficacy at doses ranging from 25 to 300 nM on endogenous and reporter protein expression.

Main Results:

• None of the tested ASOs demonstrated upregulation of endogenous or reporter protein expression.
• In some experimental conditions, the ASOs resulted in downregulation of protein expression.
• The results did not support the proposed mechanism of uORF blocking for therapeutic upregulation.

Conclusions:

• Previously described steric block ASOs targeting the RNASEH1 uORF are ineffective for upregulating primary open reading frame (pORF) protein expression.
• The therapeutic utility of this specific ASO design for uORF-mediated gene upregulation requires further investigation.
• The findings challenge the previously reported efficacy of these ASOs in modulating gene expression via uORF targeting.