Skip Navigation
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Your Environment. Your Health.

Publication Detail

Title: Ubiquitinated-PCNA protects replication forks from DNA2-mediated degradation by regulating Okazaki fragment maturation and chromatin assembly.

Authors: Thakar, Tanay; Leung, Wendy; Nicolae, Claudia M; Clements, Kristen E; Shen, Binghui; Bielinsky, Anja-Katrin; Moldovan, George-Lucian

Published In Nat Commun, (2020 05 01)

Abstract: Upon genotoxic stress, PCNA ubiquitination allows for replication of damaged DNA by recruiting lesion-bypass DNA polymerases. However, PCNA is also ubiquitinated during normal S-phase progression. By employing 293T and RPE1 cells deficient in PCNA ubiquitination, generated through CRISPR/Cas9 gene editing, here, we show that this modification promotes cellular proliferation and suppression of genomic instability under normal growth conditions. Loss of PCNA-ubiquitination results in DNA2-dependent but MRE11-independent nucleolytic degradation of nascent DNA at stalled replication forks. This degradation is linked to defective gap-filling in the wake of the replication fork and incomplete Okazaki fragment maturation, which interferes with efficient PCNA unloading by ATAD5 and subsequent nucleosome deposition by CAF-1. Moreover, concomitant loss of PCNA-ubiquitination and the BRCA pathway results in increased nascent DNA degradation and PARP inhibitor sensitivity. In conclusion, we show that by ensuring efficient Okazaki fragment maturation, PCNA-ubiquitination protects fork integrity and promotes the resistance of BRCA-deficient cells to PARP-inhibitors.

PubMed ID: 32358495 Exiting the NIEHS site

MeSH Terms: Cell Line, Tumor; Chromatin Assembly and Disassembly/genetics; Chromatin Assembly and Disassembly/physiology; Comet Assay; DNA Damage/genetics; DNA Damage/physiology; DNA Repair/genetics; DNA Repair/physiology; DNA Replication/genetics; DNA Replication/physiology; DNA/genetics; Fluorescent Antibody Technique; Genomic Instability/genetics; Genomic Instability/physiology; HEK293 Cells; HeLa Cells; Humans; Proliferating Cell Nuclear Antigen/genetics; Proliferating Cell Nuclear Antigen/metabolism*; Protein Binding; Ubiquitination/genetics; Ubiquitination/physiology

to Top