Modified siRNA Sequences for Targeted PCSK9 Gene Silencing
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Solution Overview
Problem
Current drugs for treating hypercholesterolemia and dyslipidemia, such as statins and PCSK9 inhibitors, have limitations in effectively regulating PCSK9 gene expression, necessitating the development of more potent and specific siRNA sequences to inhibit PCSK9 expression.
Innovation Solution
Designing unique siRNA sequences with alternate modifications and specific template modifications, including 2'-methoxy and 2'-fluoro alternations, to enhance the inhibitory effect on PCSK9 gene expression, and conjugating them with ligands like GalNAc for efficient liver delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If unmodified siRNA sequences are used, then the synthesis process is simple, but the inhibitory effect on PCSK9 expression is insufficient
Solution Approach 1:
The patent applies chemical modifications to the siRNA sequences, changing the chemical parameters of the nucleic acid structure. Specifically, modifications are made to the sugar ring (2'-OMe, 2'-F), base (N6-methyladenosine, pseudouridine), and phosphate backbone (phosphorothioate) to enhance the inhibitory effect on PCSK9 expression while maintaining synthesis feasibility through established chemical modification methods
Solution Approach 2:
The patent creates composite modified siRNA molecules by combining multiple chemical modification types on a single siRNA sequence. The siRNA molecules incorporate various modifications simultaneously (e.g., 2'-OMe/2'-F on sugar ring, base modifications, phosphorothioate backbone), creating a composite structure that achieves superior inhibitory effect compared to unmodified sequences
2Device complexity
If classic siRNA sequences are used, then the design is straightforward, but the therapeutic efficacy is limited
Solution Approach 1:
The patent modifies the chemical parameters of the siRNA molecules through multiple modification types: sugar ring modifications (2'-OMe, 2'-F), base modifications (N6-methyladenosine, pseudouridine), and phosphate backbone modifications (phosphorothioate). These parameter changes enhance the therapeutic efficacy by improving nuclease resistance, affinity to target RNA, and overall stability, while the design process remains systematic and repeatable
Solution Approach 2:
The patent applies different chemical modifications to specific positions and regions of the siRNA sequence rather than uniform modification. Different modifications are placed at specific locations to optimize local interactions with the target PCSK9 mRNA, enhancing the overall therapeutic efficacy through localized chemical optimization
3Ease of manufacture
If natural oligonucleotide structure is used, then the synthesis is straightforward, but the stability to nucleases is poor
Solution Approach 1:
The patent changes the chemical parameters of the oligonucleotide structure by introducing modified sugar rings (2'-OMe, 2'-F), modified bases (N6-methyladenosine, pseudouridine), and phosphorothioate backbone linkages. These parameter changes significantly improve stability to nucleases by reducing recognition and cleavage by nucleolytic enzymes, while the synthesis remains straightforward using established chemical modification methods
Solution Approach 2:
The patent uses chemically modified oligonucleotides that are designed to be resistant to degradation by nucleases in the biological environment. The modifications create a more stable molecular structure that persists longer in the body, effectively acting as a durable therapeutic agent rather than a transient molecule
4Ease of manufacture
If unmodified siRNA is used, then the cellular endocytosis is basic, but the tissue targeting is insufficient
Solution Approach 1:
The patent modifies the chemical parameters of the siRNA to enhance tissue targeting capabilities. Chemical modifications such as phosphorothioate backbone, 2'-OMe/2'-F sugar modifications, and base modifications alter the molecular properties to improve cellular endocytosis efficiency and facilitate specific tissue targeting, particularly for liver delivery, while maintaining manufacturing simplicity through established modification protocols
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 siRNA sequences achieve significant inhibition of PCSK9 expression, reducing LDL-C and total cholesterol levels in serum by up to 90% and 40% improvement compared to unmodified sequences, demonstrating enhanced therapeutic efficacy.
Implementation Method 1
RNA interference (RNAi) is a natural defense mechanism against foreign genes. siRNA can knock out target genes by recognizing specific sequences and degrading target mRNA.
Implementation Method 2
siRNA executes its function by complete Watson-Crick base pairing with mRNA
Implementation Method 3
The complete complementarity between the siRNA (the antisense strand) and the target leads to the cleavage of the target transcript at the 10 to 11 position opposite the guide strand (antisense strand) under the catalysis of the AGO2 protein.
Implementation Method 4
Chemical modification of the oligonucleotide structure is an effective method of increasing its activity, which can improve its stability to nucleases and its affinity to RNA
Implementation Method 5
conjugating them with ligands like GalNAc for efficient liver delivery
Data Source
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AI summary
The present disclosure relates to siRNAs that target and regulate PCSK9 gene expression and use thereof. Experimental results show that some alternately modified and specific template-modified oligonucleotide sequences can significantly inhibit PCSK9 expression and can be used to develop drugs to treat PCSK9-related diseases.