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Design and characterization of decoy oligonucleotides containing locked nucleic acids
Rita Crinelli1, Marzia Bianchi, Lucia Gentilini
1Istituto di Chimica Biologica 'G. Fornaini', Università degli Studi di Urbino, via Saffi 2, I-61029 Urbino, Italy.
Abstract:
Transfection of cis-element double-stranded oligonucleotides, referred to as decoy ODNs, has been reported to be a powerful tool that provides a new class of antigene strategies for gene therapy. However, one of the major limitations of the decoy approach is the rapid degradation of phosphodiester oligonucleotides by intracellular nucleases. To date, several DNA analogs have been employed to overcome this issue, but insufficient efficacy and/or specificity have limited their in vivo usefulness. In this paper we have investigated the use of conformationally restricted nucleotides in the design of decoy molecules for nuclear transcription factor kappaB (NF-kappaB). Starting from a synthetic double-stranded oligonucleotide, containing the kappaB consensus binding sequence, we designed a panel of decoy molecules modified to various extents and at various positions with locked nucleic acids (LNAs). Our results indicate that the addition of terminal LNA bases, outside the kappaB sequence, to generate LNA-DNA-LNA co-polymers was sufficient to confer appreciable protection towards nuclease digestion, without interfering with transcription factor binding. Conversely, insertion of LNA substitutions in the context of the kappaB-binding site resulted in further increased stability, but caused a loss of affinity of NF-kappaB for the target sequence. However, our results also indicate that this latter effect was apparently dependent not only on the extent but also on strand positioning of the internal LNA substitutions. This observation is of great importance since it provides evidence for the possibility of tuning DNA-LNA duplexes with internal LNAs into decoy agents with improved features in terms of biological stability and inhibitory effect.
Insights
Locked nucleic acids (LNAs) enhance the stability of decoy oligonucleotides against nuclease degradation. Modifying decoy molecules with LNAs offers a promising strategy for improved gene therapy applications.
Area of Science:
- Molecular Biology
- Gene Therapy
- Oligonucleotide Chemistry
Background:
- Decoy oligonucleotides (ODNs) are a gene therapy strategy targeting specific DNA sequences.
- Phosphodiester ODNs face limitations due to rapid degradation by intracellular nucleases.
- Existing DNA analogs have shown insufficient efficacy and specificity for in vivo applications.
Purpose of the Study:
- To investigate the use of conformationally restricted nucleotides, specifically locked nucleic acids (LNAs), in designing decoy molecules.
- To enhance the stability and efficacy of decoy molecules for nuclear transcription factor kappaB (NF-kappaB) targeting.
- To explore the impact of LNA modifications on decoy molecule stability and transcription factor binding affinity.
Main Methods:
- Design and synthesis of a panel of decoy molecules based on a double-stranded oligonucleotide with a kappaB consensus binding sequence.
- Modification of decoy molecules with locked nucleic acids (LNAs) at various positions and extents.
- Assessment of nuclease resistance and binding affinity of modified decoy molecules to NF-kappaB.
Main Results:
- Terminal LNA base additions (LNA-DNA-LNA co-polymers) conferred nuclease resistance without affecting transcription factor binding.
- Internal LNA substitutions increased stability but reduced NF-kappaB binding affinity.
- The effect of internal LNA substitutions on binding affinity was dependent on the extent and strand positioning of modifications.
Conclusions:
- Terminal LNA modifications offer a viable strategy to improve decoy ODN stability for gene therapy.
- Internal LNA modifications can be tuned to balance stability and inhibitory effects, optimizing decoy agent performance.
- This study provides evidence for developing LNA-modified DNA duplexes as potent decoy agents with enhanced biological stability and inhibitory capacity.