Evaluation of Gene Expression Knock-Down by Chemically and Structurally Modified Gapmer Antisense Oligonucleotides

Area of Science:

• Molecular Biology
• Oligonucleotide Therapeutics
• Gene Silencing

Background:

• Antisense oligonucleotides (ASOs) are a promising therapeutic modality for gene silencing.
• RNase H mediated gene silencing is a key mechanism for ASO efficacy.
• Modifications to ASO structure can significantly impact their biological and physicochemical properties.

Purpose of the Study:

• To investigate the effect of modified nucleotides within gapmer ASOs on RNase H mediated gene silencing.
• To explore the impact of introducing short hairpins as structural motifs into ASOs.
• To evaluate the influence of these modifications on the biological and physicochemical properties of pre-structured gapmers.

Main Methods:

• Analysis of modified nucleotides in gapmer antisense oligonucleotides.
• Introduction of short hairpins into antisense oligonucleotides.
• Assessment of gene silencing efficacy, specifically for the β-actin gene.
• Evaluation of biological and physicochemical properties.

Main Results:

• Two LNA residues in specific gap flanking regions of gapmer ASOs are sufficient for efficient β-actin gene knock-down.
• Incorporation of various modified nucleotides (glycyl-amino-LNA-T, 2'-O-propagyluridine, polyamine functionalized uridine, UNA) enhances inhibition of β-actin expression.
• The presence of hairpins within gapmers demonstrably improves their gene silencing properties.

Conclusions:

• Modified nucleotides, particularly LNA residues, significantly enhance the gene silencing capabilities of gapmer ASOs.
• Incorporating hairpins into ASOs further boosts their therapeutic potential by improving silencing efficiency.
• These findings provide valuable insights for the rational design of next-generation oligonucleotide therapeutics.