Unbiased Discovery of Heterogeneous DNA Repair Preferences

NOMIS Research Project

The DNA in our cells is damaged every time we go out in the sun, drink a glass of wine or even just sit perfectly still while our cells divide. To combat this threat, eukaryotes have evolved a dizzying number of ways to fix DNA damage, called the DNA-damage response (DDR). This complex, collective set of mechanisms detects DNA lesions, signals their presence and promotes their repair. Proper functioning of the DDR is critical to prevent somatic diseases such as cancer and inherited disorders such as Fanconi anemia.

Despite historical advances in understanding the overall regulation of the DDR in simple unicellular eukaryotes, there are fundamental gaps in transferring this knowledge to multicellular organisms such as humans.

While all eukaryotes share some core features, multicellular eukaryotes encompass a great diversity of specialized cell types. To determine how different tissues and cells within those tissues heterogeneously perform DNA double-strand break repair (DSBR), the Unbiased Discovery of Heterogeneous DNA Repair Preferences in Multiple Tissues of a Living Organism project aims to couple precise CRISPR-Cas–induced double-strand DNA breaks with single-cell multiomics of genotype and transcriptional state. Double-strand breaks (DSBs) are particularly noxious insults, since they disrupt the phosphate backbone and can lead to loss of chromosome integrity if unrepaired. DSBs are also central to CRISPR-Cas genome editing; the researchers thus anticipate the discovery of the mechanisms that underlie tissue-specific differences in genome-editing efficiency.

This approach has the potential to elucidate the cellular program active within each cell type that could determine a given repair outcome. The researchers hope their investigations will yield unparalleled insight into multiple levels of DSBR heterogeneity, from high-level pathway choice to molecular outcomes at single-base resolution, with paired information on cell identity and transcriptional state, to power decades of mechanistic follow-up.

The project is being led by Jacob Corn at ETH Zurich (Zurich, Switzerland). Corn is the Professor of Genome Biology at ETH Zurich.