siRNA Design for Specific Gene Silencing via Local Sequence Identity
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Solution Overview
Problem
Current RNA interference methods for gene silencing using siRNAs face challenges in specificity, as they can lead to unintended silencing of non-target genes due to partial sequence identity, complicating the identification of gene function and therapeutic applications.
Innovation Solution
Designing siRNAs with specific contiguous nucleotide sequences of 11-18 nucleotides or 9-15 nucleotides at the 3' end that are identical to target gene sequences, minimizing full-length sequence identity to other transcripts, and using siRNA pools to reduce off-target effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If siRNAs with full length sequence identity to target transcripts are used, then gene silencing efficacy is improved, but off-target silencing of non-target genes occurs
Solution Approach 1:
The patent applies local quality by concentrating sequence identity in specific local regions (contiguous stretches of 9-15 nucleotides at the 3' end or 11-18 nucleotides in the central region) rather than distributing identity throughout the entire siRNA sequence. This localized identity approach maintains effective target binding while reducing overall sequence similarity that could cause off-target effects.
Solution Approach 2:
The patent changes the parameter of sequence identity distribution by limiting identical nucleotide stretches to specific length ranges (9-15 nt at 3' end, 11-18 nt centrally) and specific positional regions. This parameter control transforms the silencing mechanism from full-length matching to region-specific matching, achieving both efficacy and specificity.
2Object-affected harmful factors
If siRNAs with partial sequence identity are used, then off-target effects are reduced, but gene silencing efficacy decreases
Solution Approach 1:
The patent maintains gene silencing efficacy by preserving local sequence identity in critical regions (3' end and central region) while reducing identity in other regions. This localized approach ensures sufficient binding affinity for target recognition while minimizing overall similarity that could lead to off-target effects.
Solution Approach 2:
The patent optimizes the parameter of contiguous identical nucleotide length to specific ranges (9-15 nt at 3' end, 11-18 nt centrally) to balance binding strength and specificity. This parameter optimization maintains enough identity for effective silencing while limiting excessive identity that would cause off-target effects.
3Object-affected harmful factors
If siRNA pools are used, then off-target effects are minimized, but design complexity increases
Solution Approach 1:
The patent segments the siRNA design into distinct functional regions with specific identity requirements: a 3' end region with 9-15 contiguous identical nucleotides and a central region with 11-18 contiguous identical nucleotides. This segmentation provides a systematic framework for designing siRNA pools, reducing complexity by establishing clear design rules for each region.
Solution Approach 2:
The patent establishes specific parameter ranges for contiguous identical nucleotides (9-15 nt at 3' end, 11-18 nt centrally) that serve as design guidelines. These quantified parameters simplify the design process by providing concrete targets for sequence selection, making pool design more systematic and less complex.
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
This approach enhances the specificity of gene silencing, allowing for effective targeting of intended genes while minimizing off-target effects, thereby improving the accuracy of gene function studies and therapeutic applications.
Implementation Method 1
RNA interference (RNAi) is a potent method to suppress gene expression in mammalian cells
Implementation Method 2
These short duplexes associate with a multiprotein complex termed RISC, and direct this complex to mRNA transcripts with sequence similarity to the siRNA
Data Source
AI summary
The invention provides methods and compositions for gene silencing by RNA interference. In particular, the invention provides methods for gene silencing or RNA knockdown using small interfering RNAs (siRNAs) having partial sequence homology to its target gene. The invention also provides methods for identifying common and/or differential responses to a plurality of different siRNAs targeting a gene. The invention also provides methods for evaluating the relative activity of the two strands of an siRNA. The invention further provides methods of designing siRNAs for gene silencing. The invention further provides methods of using siRNAs as therapeutics for treatment of diseases.