High-Throughput Methodology Allows Direct Visualization of DNA Repair

Two new high-throughput systems have been developed to facilitate the study of DNA repair kinetics. The systems, which could advance development of new cancer therapies, are described in a paper published today in Cell Reports.

The goal of chemotherapy is to kill tumor cells by inducing DNA lesions, which cause cancer cell collapse and death. “By knowing how DNA lesions occur and how they are repaired, we will learn more about how cancer develops and how we can fight it. Any new discovery in DNA repair will help develop better cancer therapies, whilst protecting our healthy cells,” says Barbara Martinez-Pastor, senior author of the study.

The team’s new methodology uses machine learning analysis to enable the tracking of DNA repair kinetics with what they say is a degree of detail and precision never before achieved. “Until now, one limiting factor in tracking DNA repair kinetics was the inability to process and analyze the amount of data generated from images taken by the microscope,” Martinez explains.

Using high-throughput microscopy that allows the acquisition of thousands of pictures of cells after induction of genetic damage, the team introduced more than 300 different proteins into the cells and evaluated in a single experiment whether they interfered with DNA repair over time. This technique has led to the discovery of nine new proteins that are involved in DNA repair.

The team also visually monitored the 300 proteins after generating genetic damage. “We saw that many proteins adhered to damaged DNA, and others did just the opposite: they moved away from the DNA lesions. The fact that they either bind to or remove themselves from damaged DNA, to allow the recruitment of repair proteins to the lesion, is a common feature of DNA repair proteins. Both phenomena are relevant,” Martinez adds.

One of the proteins discovered is PHF20. The authors showed that this protein moves away from lesions within seconds after damage to facilitate the recruitment of 53BP1, a protein critical in DNA repair. Cells without PHF20 cannot repair their DNA properly and are more sensitive to irradiation than normal cells, indicating that PHF20 is important for DNA repair.

These technologies offer new opportunities to study DNA repair and to manipulate it. “An advantage is that both platforms are very versatile and can be used to discover new genes or chemical compounds that affect DNA repair. We have evaluated hundreds of proteins in minimal time by using techniques allowing direct visualization of DNA repair.”