Researchers Identified POLD3 Function in DNA Synthesis
Scientists discovered how the POLD3 subunit coordinates essential DNA replication during mitosis.
Updated on Sept. 19, 2026 in Life Sciences
Researchers have identified that the POLD3 protein plays a critical role in coordinating leading and lagging strand DNA synthesis during mitosis. This function is essential for completing replication at MiDAS sites, a variant of Break-Induced Replication.
Why it matters
Understanding this mechanism reveals how cancer cells manage oncogene-induced DNA replication stress, providing potential targets for new therapeutic pathways. Targeting these specific replication processes could help develop treatments for complex cancers.
Experiments using high-resolution mapping of DNA replication sites demonstrated that POLD3 interacts directly with PCNA to sustain synthesis. Testing in HeLa cell clones showed that while S-phase replication remains stable, mutations to the POLD3 PCNA-interacting domain disrupt mitosis.
The players
POLD3
This protein serves as the third subunit of DNA polymerase delta and acts as a key coordinator during mitosis.
HeLa
These immortal cell lines were used as the experimental model to map DNA replication and test the effects of protein mutations.
The details
The study utilized HeLa cell clones with targeted mutations to examine how POLD3 functions during Mitotic DNA Synthesis (MiDAS). Findings indicate that POLD3 is required to bridge replication gaps, specifically during the specialized process of Break-Induced Replication.
Timeline
September 19, 2026: The research findings were published.
The Big Picture
This discovery updates the prevailing understanding of Break-Induced Replication pathways by defining the specific molecular machinery required for mitosis-specific synthesis. It shifts the theoretical framework for how cells overcome replication stress during division.
This insight into cellular division provides a foundation for the future development of targeted cancer therapies. By mapping how malignant cells manage replication stress, scientists may eventually create treatments that selectively inhibit these pathways in tumor environments.
The takeaway
The identification of POLD3 as a coordinator of mitotic synthesis offers a new angle for researchers studying oncogenic replication stress. This finding highlights the complex adjustments cells make to ensure genomic stability under extreme physiological pressure.
Further reading
For more on the molecular mechanisms of cellular division, explore our Life Sciences section.
Source note: This article includes information reported by Nature.
