# Mechanisms of chromosome damage repair in human cells

> **NIH NIH R01** · COLORADO STATE UNIVERSITY · 2022 · $292,893

## Abstract

PROJECT SUMMARY
 DNA repair by homologous recombination (HR) in tumor cells accelerates the development of resistance to
chemo- and radiotherapy and leads to the recurrence of disease. Hence, inducing HR deficiency in HR-proficient
tumors is a promising strategy to increase the efficacy of DNA-targeted therapies. Yet, we still do not know which
stage of the HR reaction is the most sensitive to inhibition and consequently the most promising to target.
However, inhibition of HR pathway intermediates during synapsis and strand invasion may be particularly
effective.
 The long-term goal of our study is to lay the groundwork for the development of novel HR-directed anti-
cancer therapeutics. The central hypothesis of our project is that human cells have evolved multiple pathways
of strand invasion. The rationale for this project is that a detailed understanding of the molecular mechanisms of
the multiple pathways of strand invasion is likely to offer a strong scientific framework whereby new strategies to
cancer therapy can be developed. The overall objectives in this application are to (i) elucidate the molecular
mechanisms of the multiple pathways of strand invasion in HR in human cells, and (ii) determine the steps in
these pathways in which the HR functions of the RAD51 activators RAD51AP1, RAD54L, and RAD54B intersect.
The central hypothesis will be tested by pursuing two specific aims: 1) Dissect the non-epistatic and epistatic
relationships between RAD51AP1, RAD54L, and RAD54B; and 2) Determine the functional roles of the
RAD51AP1-RAD54L and RAD51AP1-RAD54B protein complexes. Under the first aim, isogenic human cancer
cell lines will be used to determine the phenotypic consequences of RAD51AP1, RAD54L and/or RAD54B
deletion. Proven knockout strategies and assays to evaluate the effect that loss-of-function has on cytotoxicity,
genome stability, replication and recombination will be employed. For the second aim, biochemical assays of
strand invasion utilizing nucleosome-free and nucleosome-containing DNA substrates will be carried out, and
mutants defective in protein complex formation will be tested for complementation in cell survival assays.
 The research proposed in this application is innovative in the applicant’s opinion, because it focuses on
unraveling the poorly understood interplay between the multiple pathways of strand invasion that exist in human
cells, the intra-pathway synthetic interaction between RAD51AP1 and RAD54L, and the role of human RAD54B
in HR. The proposed research is significant because it is expected to provide strong scientific justification for the
continued development of inhibitors that target HR stimulators of strand invasion. The knowledge gained herein
also has the potential of offering new opportunities for the development of novel cancer therapies.

## Key facts

- **NIH application ID:** 10521815
- **Project number:** 1R01GM144579-01A1
- **Recipient organization:** COLORADO STATE UNIVERSITY
- **Principal Investigator:** Claudia Wiese
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $292,893
- **Award type:** 1
- **Project period:** 2022-09-01 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10521815

## Citation

> US National Institutes of Health, RePORTER application 10521815, Mechanisms of chromosome damage repair in human cells (1R01GM144579-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10521815. Licensed CC0.

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