CRISPR-Cas9 Guide RNA Programming for Scalable, Precise Genome Editing
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Solution Overview
Problem
Current genome-editing technologies, such as designer zinc fingers and TALEs, are costly, complex, and not scalable for targeting multiple positions within the eukaryotic genome, necessitating a more affordable and efficient method for precise genome perturbation.
Innovation Solution
The CRISPR-Cas system is utilized with engineered Cas9 enzymes and guide RNAs for targeted genome editing, incorporating mutations and chimeric proteins to enhance specificity and reduce toxicity, delivered via vectors like AAV and lentivirus for cell-type-specific applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If designer zinc fingers or TALEs are used for genome editing, then targeted genome perturbation can be achieved, but the cost is high and the system is complex and not scalable
Solution Approach 1:
The CRISPR-Cas9 system employs a universal Cas9 enzyme that can be programmed to target multiple different genomic loci through exchange of guide RNA molecules. This single enzyme system replaces the need for custom-designed zinc finger or TALE proteins for each target site, achieving multi-functionality and scalability while maintaining targeting precision
Solution Approach 2:
The system changes the programmable parameter from protein sequence (in zinc fingers and TALEs) to RNA sequence (guide RNA). This parameter change simplifies the design process, reduces complexity, and enables easier scaling to multiple target sites while preserving the ability to achieve precise genome editing
2Productivity
If wild-type Cas9 is used for genome editing, then efficient cleavage is achieved, but off-target effects and toxicity increase
Solution Approach 1:
The patent introduces point mutations at specific locations within the Cas9 enzyme (such as D10A, H840A, N863A, N854A) to create nickase or dead Cas9 variants. These localized changes modify the enzyme's catalytic activity to reduce off-target cleavage while maintaining on-target binding affinity and specificity
Solution Approach 2:
The patent converts the potentially harmful double-strand break activity of wild-type Cas9 into a beneficial nicking activity by introducing specific mutations. The nickase activity creates single-strand breaks that are less toxic and can be repaired more faithfully, reducing off-target effects while still enabling genome editing when two nickases target opposite strands
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 simplifies genome editing by enabling precise and scalable targeting of genetic elements, reducing off-target effects and enhancing therapeutic applications in gene therapy, drug discovery, and disease diagnosis.
Implementation Method 1
a guide sequence directs sequence-specific binding of a CRISPR complex to a target sequence
Implementation Method 2
the guide sequence is linked to a tracr mate sequence, which in turn hybridizes to a tracr sequence
Implementation Method 3
precise genome targeting technologies are needed to enable systematic reverse engineering of causal genetic variations by allowing selective perturbation of individual genetic elements
Data Source
AI summary
The invention provides for delivery, engineering and optimization of systems, methods, and compositions for manipulation of sequences and/or activities of target sequences. Provided are delivery systems and tissues or organ which are targeted as sites for delivery. Also provided are vectors and vector systems some of which encode one or more components of a CRISPR complex, as well as methods for the design and use of such vectors. Also provided are methods of directing CRISPR complex formation in eukaryotic cells to ensure enhanced specificity for target recognition and avoidance of toxicity and to edit or modify a target site in a genomic locus of interest to alter or improve the status of a disease or a condition.