Leveraging Circular Polymerization and Extension Cloning (CPEC) Method for Construction of CRISPR Screening Libraries

Area of Science:

• Genomics and Molecular Biology
• Cancer Research
• CRISPR Technology

Background:

• High-throughput functional genomics advances cancer research by identifying therapeutic targets.
• CRISPR screening is key for understanding gene function and cancer cell survival pathways.
• Custom CRISPR libraries offer enhanced specificity and flexibility over commercial options.

Purpose of the Study:

• To present a protocol for constructing custom CRISPR knockout gRNA libraries using circular polymerase extension cloning (CPEC).
• To demonstrate the application of CPEC for creating the EpiTransNuc library targeting epigenetic regulators, transcription factors, and nuclear proteins.
• To highlight the efficiency and flexibility of CPEC for diverse gRNA library construction needs.

Main Methods:

• Utilized circular polymerase extension cloning (CPEC), a PCR-based method, for DNA fragment assembly.
• Constructed a custom CRISPR library (EpiTransNuc) targeting epigenetic regulators, transcription factors, and nuclear proteins.
• Employed PCR-based backbone linearization and skipped traditional restriction digestion and ligation steps.

Main Results:

• Successfully assembled the EpiTransNuc gRNA library with 40,820 gRNAs (10 per gene) and 100 non-targeting controls on a lentiGuide-Puro backbone.
• Demonstrated CPEC as an efficient and cost-effective cloning technique for large-scale gRNA library construction.
• Showcased the flexibility of CPEC for tailoring gRNA composition and number in custom libraries.

Conclusions:

• CPEC is a streamlined and efficient method for constructing custom CRISPR gRNA libraries.
• The developed protocol facilitates the creation of targeted libraries for specific research applications in cancer genomics.
• This approach enhances the identification of novel cancer gene targets and therapeutic strategies.