# The interplay of TIMELESS and PARP1 in DNA replication fork stability

> **NIH NIH R01** · STATE UNIVERSITY NEW YORK STONY BROOK · 2024 · $313,619

## Abstract

PROJECT SUMMARY
DNA is particularly vulnerable to damage during replication, and perturbation of the replisome activity leads to
the accumulation of stalled replication forks, causing DNA breakage and chromosomal abnormalities. Such
genome instability is aggravated when genome surveillance mechanisms get disrupted at replication forks,
which is known to be a key event for tumorigenesis. Hence, knowledge on the principles by which DNA
replication fork integrity is preserved is critical for understanding the molecular checkpoint that keeps genome
stable and developing strategies for the treatment of human diseases, including cancer where DNA replication
goes awry. The DNA replication fork is supported by the multi-protein replication machinery that coordinates
DNA unwinding and nascent strand synthesis, which is undertaken by the CMG helicase and DNA
polymerases. TIMELESS (TIM) and its heterodimeric partner TIPIN constitute a core scaffold of the fork
protection complex (FPC) that links the helicase-polymerase movement, thus preventing uncoupling of their
activities, which otherwise would destabilize the replisome structure and impair replication fork progression.
While its name implies a critical role in safeguarding DNA replication, the exact nature of the FPC in engaging
diverse protective functions coordinated at both active and stalled forks remains largely uncharacterized. Given
that active remodeling of stressed forks and collaboration of DNA replication and repair enzymes are
necessary for accommodating many DNA-protein transactions that stabilize and recover stalled forks, the FPC
is expected to function as a dynamic platform to coordinate DNA replication processes and adapt stress
response signaling to rescue damaged forks. We hereby propose to explicate the function of TIM in the FPC in
preserving replication fork integrity and protecting stalled forks. Guided by our extensive preliminary data
supporting its dynamic interaction with poly(ADP-ribose) polymerase 1 (PARP1), an emerging regulator of
DNA replication and a target of cancer therapy, we hypothesize that the intricate interplay of TIM and PARP1
constitutes a central, yet largely unexplored, mechanism to regulate DNA replication and protect stalled forks
at multiple levels, which is reinforced to counteract the fork instability of BRCA1/2-deficient cells. Using cellular,
biochemical, and genetic approaches in various engineered human cell lines, we will define the roles of the
TIM-PARP1 interaction (1) in the replisome function at active forks, focusing on Okazaki fragment processing,
(2) in the process of stalled fork protection via regulation of TIM proteolysis, and (3) in conjunction with the
BRCA1/2-dependent fork stabilization pathway. Together, our studies will reveal a new regulatory scheme for
the maintenance of DNA replication fork integrity through the collaborative action of TIM and PARP1 within the
FPC. Ultimately, such knowledge will provide valuable insight into how ...

## Key facts

- **NIH application ID:** 10875531
- **Project number:** 5R01GM144399-03
- **Recipient organization:** STATE UNIVERSITY NEW YORK STONY BROOK
- **Principal Investigator:** Hyungjin Kim
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $313,619
- **Award type:** 5
- **Project period:** 2022-09-01 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10875531

## Citation

> US National Institutes of Health, RePORTER application 10875531, The interplay of TIMELESS and PARP1 in DNA replication fork stability (5R01GM144399-03). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10875531. Licensed CC0.

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