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Updated: Jun 13, 2026
07:27
Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
Published on: April 29, 2010
Continued primer synthesis at stalled replication forks contributes to checkpoint activation
Christopher Van1, Shan Yan, W Matthew Michael
1Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA.
The Journal of Cell Biology
|April 14, 2010
Summary
Replication forks stall but continue DNA synthesis via new primers, independent of the ATR checkpoint. Accumulation of these primers enhances checkpoint activation, aiding fork recovery in higher eukaryotes.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- DNA Replication
Background:
- Stalled replication forks trigger the ATR-mediated checkpoint for stabilization.
- The precise mechanism of single-stranded DNA (ssDNA) generation at stalled forks and subsequent recovery in eukaryotes remains unclear.
Purpose of the Study:
- Investigate how stalled replication forks generate checkpoint signals.
- Elucidate the mechanisms of replication fork recovery and restart in higher eukaryotes.
Main Methods:
- Utilized Xenopus laevis egg extracts for in vitro replication studies.
- Employed defined DNA structures to analyze DNA synthesis and checkpoint activation.
Main Results:
- DNA replication persists at stalled forks through new primer synthesis, independent of the ATR checkpoint.
- This synthesis relies on proliferating cell nuclear antigen (PCNA), Pol-delta, and Pol-epsilon, contributing to Chk1 phosphorylation.
- Increasing primer-template junctions amplifies Chk1 phosphorylation, even with a fixed ssDNA amount.
Conclusions:
- New primers are synthesized by leading and lagging strand polymerases at stalled forks.
- Accumulation of these primers likely contributes to activating the DNA replication checkpoint.
- This process is crucial for replication fork recovery and restart in higher eukaryotes.
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