Compact and highly active next-generation libraries for CRISPR-mediated gene repression and activation

Area of Science:

• Molecular Biology
• Genomics
• Gene Editing Technologies

Background:

• Nucleosomes impede CRISPR/Cas9 access to DNA, limiting its application.
• Previous CRISPR/Cas9 systems showed non-specific toxicity.
• Need for precise tools for transcriptional repression and activation.

Purpose of the Study:

• Develop a predictive algorithm for highly effective single-guide RNAs (sgRNAs).
• Design next-generation genome-scale CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa) libraries.
• Establish CRISPRi and CRISPRa as premier tools for functional genomics.

Main Methods:

• Developed a comprehensive algorithm integrating chromatin, position, and sequence features.
• Designed genome-scale CRISPRi and CRISPRa libraries for human and mouse genomes.
• Performed CRISPRi screens in K562 cells to assess sgRNA activity and toxicity.

Main Results:

• The algorithm accurately predicts effective sgRNAs for CRISPRi and CRISPRa.
• Designed CRISPRi and CRISPRa libraries show high sgRNA activity.
• CRISPRi demonstrated no detectable non-specific toxicity.
• Over 90% of essential genes detected with minimal false positives using a compact library.

Conclusions:

• CRISPRi and CRISPRa are powerful tools for loss- and gain-of-function studies.
• The developed algorithm provides a general strategy for identifying Cas9 target sites.
• This work advances the precision and safety of CRISPR-based functional genomics.