Maximizing CRISPRi efficacy and accessibility with dual-sgRNA libraries and optimal effectors

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• CRISPR interference (CRISPRi) allows tunable gene knockdown in mammalian cells.
• Previous CRISPRi screens were limited by large sgRNA libraries and inconsistent knockdown.
• Wider CRISPRi screening deployment faced challenges in cell model generation.

Purpose of the Study:

• To develop next-generation CRISPRi tools for robust and consistent gene knockdown.
• To create ultra-compact sgRNA libraries and efficient effector constructs.
• To establish best practices for CRISPRi genetic screening in mammalian systems.

Main Methods:

• Empirical sgRNA selection combined with dual-sgRNA library design for library compactness and activity.
• Comparison of CRISPRi effectors, identifying Zim3-dCas9 for strong on-target knockdown with minimal off-target effects.
• Engineering of cell lines with stable Zim3-dCas9 expression for reproducible knockdown.

Main Results:

• Development of an ultra-compact (1-3 elements per gene) and highly active CRISPRi sgRNA library.
• Zim3-dCas9 demonstrated superior performance with strong knockdown and low non-specific effects.
• Engineered cell lines exhibited stable Zim3-dCas9 expression and robust gene knockdown.

Conclusions:

• The developed CRISPRi reagents and methods enable efficient and consistent gene knockdown.
• These advancements overcome previous limitations, facilitating broader application of CRISPRi screening.
• The study establishes best practices for CRISPRi genetic screening, supported by publicly available reagents.