CopyCatchers are versatile active genetic elements that detect and quantify inter-homolog somatic gene conversion.

Area of Science:

• Molecular Biology
• Genetics
• Gene Editing Technologies

Background:

• CRISPR-based gene drives utilize homology-directed repair (HDR) for super-Mendelian transmission in germlines.
• Widespread somatic mutations from active genetic elements are observed, but their genetic basis is unclear, often assumed to be non-homologous end-joining (NHEJ).

Purpose of the Study:

• To develop and utilize CopyCatcher systems for detecting and quantifying somatic gene conversion (SGC) events.
• To investigate the genetic underpinnings of somatic mutations induced by gene-drive elements.
• To identify factors influencing SGC efficiency and explore their implications for gene therapy.

Main Methods:

• Development of CopyCatcher systems in Drosophila to measure SGC rates at distinct genetic loci.
• Implementation of RNAi-based genetic screens to identify genes affecting SGC efficiency.
• Validation of findings in human HEK293T cells, examining SGC with different template types.

Main Results:

• CopyCatcher systems revealed unexpectedly high rates of SGC in Drosophila eye and thoracic epidermis.
• Genetic screens identified several novel loci that modulate SGC efficiency.
• Downregulation of c-MYC enhanced SGC mediated by both plasmid and homologous chromosome templates in human cells.

Conclusions:

• CopyCatcher systems are effective tools for discovering mechanisms of SGC.
• The findings challenge assumptions about somatic mutation generation and highlight the role of SGC.
• This research provides insights into potential gene therapy strategies by understanding and manipulating SGC.