# Regulation of the DNA damage Response

> **NIH NIH R01** · STANFORD UNIVERSITY · 2020 · $422,754

## Abstract

PROJECT SUMMARY
The long-term goal of this research program is to understand how human cells respond to replication stress,
the slowing or stalling of DNA replication induced by barriers to replication fork progression. Fork stalling
barriers can be induced environmentally by alkylating agents, crosslinking agents and aldehydes, or they can
arise from endogenous DNA damage, secondary DNA structures or interference with transcription. Prolonged
replication fork stalling can lead to DNA break formation and a failure to complete DNA replication. This is turn
can result in genome instability and mutagenesis, properties that drive cancers and affect their sensitivity to
chemotherapy. Fortunately, cells can respond to replication stress in multiple ways, depending on the barrier
encountered. Two crucial components of the replication stress response involve fork slowing and replication
fork reversal, a process that involves reannealing of the unwound template DNA and annealing of nascent
DNA strands. Fork reversal is thought to promote DNA repair, stabilize the replication fork and facilitate certain
forms of fork restart. It can also allow for the error-free replication of damaged DNA by providing the
undamaged sister chromatid as a template for DNA replication. When fork reversal occurs and how it is
regulated in the cell are poorly understood. In the previous funding period, we made the surprising finding that
the DNA translocase and fork reversal enzyme, HLTF, is needed to slow replication forks during replication
stress. This fork slowing requires HLTF's fork reversal activity. HLTF-deficient cells also proliferate better under
replication stress conditions. This combination of unusual phenotypes is unique to HLTF among fork
remodelers. The objective of this application is to characterize this stress-resistant, potentially error-prone
replication mode at the molecular and cellular level, thereby addressing fundamental questions about the
balance of replication fork progression and fork reversal during replication stress. In the first aim, we will
explore how HLTF processes replication forks to slow their progression and induce DNA breaks. In the second
aim, we will determine the mechanisms and mutagenic consequences of stress-resistant DNA replication and
unrestrained fork progression. Finally, in the third aim, we will probe the mechanisms of cell survival under
replication stress, searching for targets that contribute to stress resistance in HLTF-deficient cells. These
experiments will capitalize on cutting-edge genomic and proteomic approaches to solve fundamental problems
regarding replication fork reversal and replication stress resistance.
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## Key facts

- **NIH application ID:** 9899103
- **Project number:** 5R01ES016486-18
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** Karlene A Cimprich
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $422,754
- **Award type:** 5
- **Project period:** 2002-05-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9899103

## Citation

> US National Institutes of Health, RePORTER application 9899103, Regulation of the DNA damage Response (5R01ES016486-18). Retrieved via AI Analytics 2026-06-10 from https://api.ai-analytics.org/grant/nih/9899103. Licensed CC0.

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