5′-Modified dsRNA for RISC Loading Control
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Solution Overview
Problem
Existing RNAi therapies face challenges due to off-target effects caused by the loading of the sense strand into the RISC complex, leading to unintended gene silencing.
Innovation Solution
The development of double-stranded RNA (dsRNA) molecules with specific modifications at the 5′-end of the sense and antisense strands, such as 5′-morpholino, 5′-dimethylamino, inverted abasic, L-sugar, 5′-deoxy, or inverted abasic locked nucleic acid modifications, and the use of 5′-E-vinylphosphanate modifications in the antisense strand, to reduce or inhibit the loading of the sense strand into the RISC complex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard dsRNA molecules are used for RNAi therapy, then gene silencing activity is achieved, but off-target effects occur due to sense strand loading into RISC complex
Solution Approach 1:
The patent applies local quality by introducing specific modifications at the 5′-end of the sense strand (such as 5′-deoxy, 5′-morpholino, or inverted abasic modifications) while leaving the rest of the molecule unchanged. This localized modification selectively prevents sense strand loading into RISC without affecting the antisense strand's ability to guide gene silencing, thereby resolving the contradiction between achieving gene silencing activity and avoiding off-target effects.
Solution Approach 2:
The patent employs asymmetry by creating an asymmetric structure where the sense and antisense strands have different 5′-end configurations. The sense strand is modified to prevent RISC loading, while the antisense strand remains unmodified or differently modified to maintain its silencing function. This asymmetric design ensures that only the antisense strand loads into RISC, eliminating off-target effects while preserving on-target gene silencing.
2Object-generated harmful factors
If 5′-end modifications are introduced to the sense strand to prevent RISC loading, then off-target effects are reduced, but molecular structure complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying specific chemical parameters at the 5′-end of the sense strand, such as removing the 5′-phosphate group (5′-deoxy), adding a morpholino group (5′-morpholino), or introducing an inverted abasic modification. These parameter changes alter the molecular recognition properties of the sense strand, preventing its loading into RISC while maintaining the overall dsRNA structure and silencing function, thus resolving the contradiction between reducing off-target effects and maintaining structural simplicity.
Data Source
AI summary
One aspect of the present invention relates to double-stranded RNA (dsRNA) agent capable of inhibiting the expression of a target gene. Other aspects of the invention relate to pharmaceutical compositions comprising these dsRNA molecules suitable for therapeutic use, and methods of inhibiting the expression of a target gene by administering these dsRNA molecules, e.g., for the treatment of various disease conditions.