About This Project

Radiation damages DNA and contributes to aging, cancer, and other diseases. Deinococcus radiodurans survives radiation doses thousands of times higher than humans thanks in part to PprI, a protein that activates DNA repair. Remarkably, PprI may also protect human cells, but how it works remains unknown. We will test PprI in human cells to uncover its mechanism and identify the proteins it interacts with, laying the groundwork for new radiation-protective therapies.

Ask the Scientists

What is the context of this research?

Every day, human cells experience DNA damage from radiation, oxidative stress, aging, and disease. Although our cells possess sophisticated DNA repair pathways, these protective mechanisms are often insufficient after severe injury, contributing to tissue damage and disease.

One of the most radiation-resistant organisms ever discovered, Deinococcus radiodurans, survives by activating a coordinated stress response through a protein called PprI (also known as IrrE).

Previous studies have shown that PprI can also reduce radiation damage in mammalian cells, even though humans do not possess a known PprI pathway. How PprI produces this protective effect in human cells remains unknown.

This project will determine whether PprI enhances recovery from DNA damage in human cells and whether its protease activity is required for this effect.

What is the significance of this project?

If PprI activates endogenous repair pathways in mammalian cells, it could reveal a previously unrecognized mechanism for enhancing cellular resilience following DNA damage. Rather than replacing damaged cells or permanently altering the genome, this approach seeks to understand whether existing repair systems can be temporarily strengthened during periods of acute stress. Insights from this work could inform future strategies for protecting healthy tissues during radiation therapy, improving recovery after ischemic injury, enhancing organ preservation, and reducing cellular damage associated with disease. This project is designed as a proof-of-concept study to generate the first mechanistic evidence needed to determine whether PprI represents a promising lead for future therapeutic development or a gateway to discovering new regulators of human cellular repair.

What are the goals of the project?

The primary goal of this project is to determine whether the bacterial stress-response protein PprI enhances recovery from radiation-induced DNA damage in human cells and whether its protease activity is required for this effect. We will compare two PprI variants—wild-type and a catalytically inactive (protease-dead) mutant—alongside an empty-vector control in primary human endothelial cells and HEK293T cells for independent validation. Cell survival will be assessed following 0, 2, 4, and 6 Gy radiation. Mechanistic studies will evaluate γH2AX foci, RAD51 foci, and Annexin V staining, with all experiments performed in three independent biological replicates. Together, these studies will determine whether PprI provides reproducible radioprotection and define whether its protease activity is required to promote DNA repair in human cells, providing a strong foundation for future mechanistic studies.