Modified Antisense Oligonucleotides for Precise ADAR RNA Editing
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Solution Overview
Problem
Existing RNA editing technologies face challenges in achieving specific and efficient adenosine deamination in target RNA molecules using endogenous ADAR enzymes without the need for genetic modification or recombinant ADAR proteins, and often result in promiscuous editing.
Innovation Solution
The use of chemically modified antisense oligonucleotides (AONs) that form a double-stranded nucleic acid complex with target RNA, recruiting endogenous ADAR enzymes for precise deamination, where the nucleotide opposite the target adenosine has specific chemical modifications such as 2′,2′-difluoro or 2′-fluoro-2′-methyl substitutions, and may include nucleotide analogs like pseudoisocytidine or Benner's base Z to enhance editing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oligonucleotides are used to target specific adenosines for editing, then editing specificity should improve, but promiscuous editing occurs at multiple adenosine positions
Solution Approach 1:
The patent applies local quality by introducing specific chemical modifications only at the orphan nucleotide position (opposite the target adenosine) while leaving other positions unmodified or with different modifications. This localized modification strategy ensures that the ADAR enzyme is recruited specifically to the intended target site, preventing promiscuous editing at other adenosine positions while maintaining high editing specificity.
Solution Approach 2:
The patent utilizes parameter changes by modifying the chemical structure of the orphan nucleotide (changing sugar moieties, nucleobases, or both) to optimize the interaction with ADAR enzymes. These parameter changes in the nucleotide structure enhance the enzyme's affinity for the target site, thereby improving editing specificity and reducing off-target effects.
2Device complexity
If endogenous ADAR enzymes are used for RNA editing, then the system becomes simpler and avoids genetic modification, but editing efficiency and specificity are insufficient
Solution Approach 1:
The patent employs the chemically modified oligonucleotide as an intermediary that bridges the gap between simple endogenous ADAR enzyme usage and high editing efficiency. The modified oligonucleotide acts as a recruiter that binds to ADAR enzymes and guides them to the specific target adenosine, thereby maintaining system simplicity while significantly improving editing efficiency through the intermediary's targeted recruitment capability.
Solution Approach 2:
The patent replaces complex mechanical systems (such as fusion proteins requiring genetic modification and transfection) with a chemical solution. By using chemically modified oligonucleotides that can be directly administered and that recruit endogenous ADAR enzymes through chemical interactions, the system achieves high editing efficiency without the mechanical complexity of genetic engineering and protein delivery systems.
3Productivity
If chemical modifications are introduced in the oligonucleotide to improve editing efficiency, then editing efficiency improves, but the complexity of the oligonucleotide structure increases
Solution Approach 1:
The patent applies local quality by introducing chemical modifications only at specific positions in the oligonucleotide, particularly at the orphan nucleotide position opposite the target adenosine. This localized modification approach improves editing efficiency at the target site while avoiding the unnecessary complexity that would arise from modifying all positions in the oligonucleotide structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified AONs enable efficient and specific deamination of target adenosines in RNA, improving therapeutic potential by utilizing endogenous ADAR enzymes, enhancing editing efficiency and reducing off-target effects.
Implementation Method 1
form a double stranded nucleic acid complex with a target RNA molecule
Implementation Method 2
recruiting an adenosine deaminating enzyme for deamination of a target adenosine
Implementation Method 3
the nucleotide opposite the target adenosine has specific chemical modifications such as 2′,2′-difluoro or 2′-fluoro-2′-methyl substitutions
Data Source
AI summary
The invention relates to antisense oligonucleotides that can form a double stranded nucleic acid complex with a target RNA molecule, wherein the double stranded nucleic acid complex is capable of recruiting an adenosine deaminating enzyme for deamination of a target adenosine in the target RNA molecule, wherein the nucleotide in the AON that is directly opposite the target adenosine comprises a 2′,2′-disubstitution, preferably a 2′,2′-difluro substitution in the ribose moiety.