# Defining DNA resection and protein localization changes that occur during DSB repair

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA SANTA BARBARA · 2024 · $352,679

## Abstract

DNA double strand break (DSB) repair pathways resolve DNA lesions that arise during cellular
metabolism or as the by-product of cell damage. Human DSB repair pathways fall into two distinct categories:
end joining (EJ) pathways that rejoin the DSB molecule, and homology directed repair (HDR) pathways that use
a template molecule to repair the DSB molecule. The factors that cells use to decide between EJ and HDR repair
pathways remain incompletely defined. Many studies have shown that the cell cycle regulates DSB pathway
choice, yet cultures arrested at points in the cell cycle that favor HDR still repair the majority of DSBs using EJ.
The long-term goal of the research in my lab is to comprehensively define factors that bias DSB repair in sufficient
detail that we can predict DSB repair outcomes based on the initial conditions inside a cell. Pursuit of this goal
will improve our understanding of DNA repair and related processes, enable new generations of gene editing
reagents with greatly increased efficacy, and suggest new strategies to diagnose and treat human DNA repair
pathologies, including cancer and aging.
 Over the next five years, we will develop a holistic model for DSB repair that describes DNA repair events
occurring on the DSB and template molecules. Our goals in generating this model are to define the irreversible
commitment step between EJ/HDR and to understand if cells sense their capacity to perform HDR before they
pass commitment. These are important challenges for the cell, because inappropriate HDR can cause cell death
or genomic instability. We hypothesize that cells have the heretofore unmeasured ability to develop DSB repair
complexes in parallel, and that parallel maturation of DSB repair complexes plays a role both in the EJ/HDR
commitment and as a checkpoint for these repair pathways. Parallel development of EJ and HDR complexes
either on the DSB molecule or split between the DSB and template molecule would allow cells to simultaneously
develop different types of repair before committing to one or the other. The ability to generate mature repair
complexes prior to commitment would make DNA repair substantially less risky. Our practical approach is to
develop genomic and proteomic techniques that allow us to measure DSB repair intermediates with
unprecedented temporal and spatial resolution. We will use these techniques to define how protein complexes
associate with chromatin over time and, crucially, the strandedness of DNA bound to DSB repair proteins.
Measuring this latter parameter will allow us to determine when events occur in relation to the EJ/HDR decision
and thus understand when and how this decision is made. We also explore mechanisms of communication
between multiple DSB repair complexes assembled in parallel onto chromatin. Parallel events are especially
informative because they indicate a dynamic system in which cells simultaneously explore multiple DSB repair
pathways, thereby preserving choice until repair...

## Key facts

- **NIH application ID:** 10846593
- **Project number:** 5R35GM142975-04
- **Recipient organization:** UNIVERSITY OF CALIFORNIA SANTA BARBARA
- **Principal Investigator:** Chris Richardson
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $352,679
- **Award type:** 5
- **Project period:** 2021-08-12 → 2026-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10846593

## Citation

> US National Institutes of Health, RePORTER application 10846593, Defining DNA resection and protein localization changes that occur during DSB repair (5R35GM142975-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10846593. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*