During nuclear DNA replication, proofreading-deficient DNA polymerase α (Pol α) initiates Okazaki fragment synthesis with lower fidelity than bulk replication by proofreading-proficient Pol δ or Pol ε. Here, we provide evidence that the exonuclease activity of mammalian flap endonuclease (FEN1) excises Pol α replication errors in a MutSα-dependent, MutLα-independent mismatch repair process we call Pol α-segment error editing (AEE). We show that MSH2 interacts with FEN1 and facilitates its nuclease activity to remove mismatches near the 5' ends of DNA substrates. Mouse cells and mice encoding FEN1 mutations display AEE deficiency, a strong mutator phenotype, enhanced cellular transformation, and increased cancer susceptibility. The results identify a novel role for FEN1 in a specialized mismatch repair pathway and a new cancer etiological mechanism.
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http://dx.doi.org/10.15252/embj.201489865 | DOI Listing |
J Biol Chem
January 2025
Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), The province and ministry co-sponsored collaborative innovation center for medical epigenetics, Tianjin Key Laboratory of Medical Epigenetics, Tianjin Medical University, 300070 Tianjin, P. R. CHINA. Electronic address:
Ubiquitination of the proliferating cell nuclear antigen (PCNA) by the budding yeast protein Rad5 have important functions in replication stress responses. Rad5 together with the Ubc13-Mms2 complex attaches Lys63-linked ubiquitin chain to a highly conserved Lys164 residue in PCNA. The reaction requires prior PCNA mono-ubiquitination by the Rad6-Rad18 complex and signals for error-free DNA damage tolerance responses.
View Article and Find Full Text PDFMol Cell
January 2025
Institute for Cancer Genetics and Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Pediatrics and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA. Electronic address:
DNA replication, a fundamental process in all living organisms, proceeds with continuous synthesis of the leading strand by DNA polymerase ε (Pol ε) and discontinuous synthesis of the lagging strand by polymerase δ (Pol δ). This inherent asymmetry at each replication fork necessitates the development of methods to distinguish between these two nascent strands in vivo. Over the past decade, strand-specific sequencing strategies, such as enrichment and sequencing of protein-associated nascent DNA (eSPAN) and Okazaki fragment sequencing (OK-seq), have become essential tools for studying chromatin replication in eukaryotic cells.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Chromosome Biomedical Engineering, School of Life Science, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori, 683‑8503, Japan.
Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutations of the dystrophin gene, which spans 2.4 Mb on the X chromosome. Creatine kinase (CK) activity in blood and titin fragment levels in urine have been identified as biomarkers in DMD to monitor disease progression and evaluate therapeutic intervention.
View Article and Find Full Text PDFEur J Pharm Sci
February 2025
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan. Electronic address:
The formation of protein aggregates, which can be immunogenic and lower the efficacy and safety of protein drugs, has been an issue in biopharmaceutical development for more than a decade. Although protein drugs are often shipped as frozen material, the effect of the accidental dropping of frozen proteins, which can occur during shipping and handling, on the physical stability has not been studied. Here, a frozen Fc fusion protein was subjected to dropping stress and the increase in the aggregate concentration was evaluated.
View Article and Find Full Text PDFACS Phys Chem Au
November 2024
Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom.
Time-resolved extreme ultraviolet spectroscopy was used to investigate photodissociation within the iodobenzene C-band. The carbon-iodine bond of iodobenzene was photolyzed at 200 nm, and the ensuing dynamics were probed at 10.3 nm (120 eV) over a 4 ps range.
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