Site-specific replication fork barriers (RFBs) have proven valuable tools for studying mechanisms of repair at sites of replication fork stalling in prokaryotes and yeasts. We adapted the Escherichia coli Tus-Ter RFB for use in mammalian cells and used it to trigger site-specific replication fork stalling and homologous recombination (HR) at a defined chromosomal locus in mammalian cells. By comparing HR responses induced at the Tus-Ter RFB with those induced by a site-specific double-strand break (DSB), we have begun to uncover how the mechanisms of mammalian stalled fork repair differ from those underlying the repair of a replication-independent DSB. Here, we outline how to transiently express the Tus protein in mES cells, how to use flow cytometry to score conservative and aberrant repair outcomes, and how to quantify distinct repair outcomes in response to replication fork stalling at the inducible Tus-Ter chromosomal RFB.
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http://dx.doi.org/10.1007/978-1-0716-0644-5_23 | DOI Listing |
Mol 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 PDFCell Death Dis
January 2025
Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China.
Mitochondrial oxidative phosphorylation (OXPHOS) is a therapeutic vulnerability in glycolysis-deficient cancers. Here we show that inhibiting OXPHOS similarly suppresses the proliferation and tumorigenicity of glycolytically competent colorectal cancer (CRC) cells in vitro and in patient-derived CRC xenografts. While the increased glycolytic activity rapidly replenished the ATP pool, it did not restore the reduced production of aspartate upon OXPHOS inhibition.
View Article and Find Full Text PDFNat Commun
January 2025
DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK.
Human DNA licensing initiates replication fork assembly and DNA replication. This reaction promotes the loading of the hMCM2-7 complex on DNA, which represents the core of the replicative helicase that unwinds DNA during S-phase. Here, we report the reconstitution of human DNA licensing using purified proteins.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Département de Biologie, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
To achieve replicative immortality, cancer cells must activate telomere maintenance mechanisms. In 10 to 15% of cancers, this is enabled by recombination-based alternative lengthening of telomeres pathways (ALT). ALT cells display several hallmarks including heterogeneous telomere length, extrachromosomal telomeric repeats, and ALT-associated PML bodies.
View Article and Find Full Text PDFDNA Repair (Amst)
December 2024
Department of Data Science, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Pathology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA.
Tandem duplications (TD) are among the most frequent type of structural variant (SV) in the cancer genome. They are characterized by a single breakpoint junction that defines the boundaries and the size of the duplicated segment. Cancer-associated TDs often increase oncogene copy number or disrupt tumor suppressor gene function, and thus have important roles in tumor evolution.
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