1
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Benedict B, Kristensen SM, Duxin JP. What are the DNA lesions underlying formaldehyde toxicity? DNA Repair (Amst) 2024; 138:103667. [PMID: 38554505 DOI: 10.1016/j.dnarep.2024.103667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/22/2024] [Accepted: 03/01/2024] [Indexed: 04/01/2024]
Abstract
Formaldehyde is a highly reactive organic compound. Humans can be exposed to exogenous sources of formaldehyde, but formaldehyde is also produced endogenously as a byproduct of cellular metabolism. Because formaldehyde can react with DNA, it is considered a major endogenous source of DNA damage. However, the nature of the lesions underlying formaldehyde toxicity in cells remains vastly unknown. Here, we review the current knowledge of the different types of nucleic acid lesions that are induced by formaldehyde and describe the repair pathways known to counteract formaldehyde toxicity. Taking this knowledge together, we discuss and speculate on the predominant lesions generated by formaldehyde, which underly its natural toxicity.
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Affiliation(s)
- Bente Benedict
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Stella Munkholm Kristensen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Julien P Duxin
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
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2
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Audrey A, Kok YP, Yu S, de Haan L, van de Kooij B, van den Tempel N, Chen M, de Boer HR, van der Vegt B, van Vugt MATM. RAD52-dependent mitotic DNA synthesis is required for genome stability in Cyclin E1-overexpressing cells. Cell Rep 2024; 43:114116. [PMID: 38625790 DOI: 10.1016/j.celrep.2024.114116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/28/2024] [Accepted: 03/29/2024] [Indexed: 04/18/2024] Open
Abstract
Overexpression of Cyclin E1 perturbs DNA replication, resulting in DNA lesions and genomic instability. Consequently, Cyclin E1-overexpressing cancer cells increasingly rely on DNA repair, including RAD52-mediated break-induced replication during interphase. We show that not all DNA lesions induced by Cyclin E1 overexpression are resolved during interphase. While DNA lesions upon Cyclin E1 overexpression are induced in S phase, a significant fraction of these lesions is transmitted into mitosis. Cyclin E1 overexpression triggers mitotic DNA synthesis (MiDAS) in a RAD52-dependent fashion. Chemical or genetic inactivation of MiDAS enhances mitotic aberrations and persistent DNA damage. Mitosis-specific degradation of RAD52 prevents Cyclin E1-induced MiDAS and reduces the viability of Cyclin E1-overexpressing cells, underscoring the relevance of RAD52 during mitosis to maintain genomic integrity. Finally, analysis of breast cancer samples reveals a positive correlation between Cyclin E1 amplification and RAD52 expression. These findings demonstrate the importance of suppressing mitotic defects in Cyclin E1-overexpressing cells through RAD52.
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Affiliation(s)
- Anastasia Audrey
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Yannick P Kok
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Shibo Yu
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Lauren de Haan
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Bert van de Kooij
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Nathalie van den Tempel
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Mengting Chen
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - H Rudolf de Boer
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Bert van der Vegt
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Marcel A T M van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands.
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3
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Bournaka S, Badra-Fajardo N, Arbi M, Taraviras S, Lygerou Z. The cell cycle revisited: DNA replication past S phase preserves genome integrity. Semin Cancer Biol 2024; 99:45-55. [PMID: 38346544 DOI: 10.1016/j.semcancer.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/23/2024] [Accepted: 02/05/2024] [Indexed: 02/20/2024]
Abstract
Accurate and complete DNA duplication is critical for maintaining genome integrity. Multiple mechanisms regulate when and where DNA replication takes place, to ensure that the entire genome is duplicated once and only once per cell cycle. Although the bulk of the genome is copied during the S phase of the cell cycle, increasing evidence suggests that parts of the genome are replicated in G2 or mitosis, in a last attempt to secure that daughter cells inherit an accurate copy of parental DNA. Remaining unreplicated gaps may be passed down to progeny and replicated in the next G1 or S phase. These findings challenge the long-established view that genome duplication occurs strictly during the S phase, bridging DNA replication to DNA repair and providing novel therapeutic strategies for cancer treatment.
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Affiliation(s)
- Spyridoula Bournaka
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece
| | - Nibal Badra-Fajardo
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece
| | - Marina Arbi
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece
| | - Stavros Taraviras
- Department of Physiology, Medical School, University of Patras, Patras 26504, Greece
| | - Zoi Lygerou
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece.
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4
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Leung W, Baxley RM, Traband E, Chang YC, Rogers CB, Wang L, Durrett W, Bromley KS, Fiedorowicz L, Thakar T, Tella A, Sobeck A, Hendrickson EA, Moldovan GL, Shima N, Bielinsky AK. FANCD2-dependent mitotic DNA synthesis relies on PCNA K164 ubiquitination. Cell Rep 2023; 42:113523. [PMID: 38060446 PMCID: PMC10842461 DOI: 10.1016/j.celrep.2023.113523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/09/2023] [Accepted: 11/15/2023] [Indexed: 12/30/2023] Open
Abstract
Ubiquitination of proliferating cell nuclear antigen (PCNA) at lysine 164 (K164) activates DNA damage tolerance pathways. Currently, we lack a comprehensive understanding of how PCNA K164 ubiquitination promotes genome stability. To evaluate this, we generated stable cell lines expressing PCNAK164R from the endogenous PCNA locus. Our data reveal that the inability to ubiquitinate K164 causes perturbations in global DNA replication. Persistent replication stress generates under-replicated regions and is exacerbated by the DNA polymerase inhibitor aphidicolin. We show that these phenotypes are due, in part, to impaired Fanconi anemia group D2 protein (FANCD2)-dependent mitotic DNA synthesis (MiDAS) in PCNAK164R cells. FANCD2 mono-ubiquitination is significantly reduced in PCNAK164R mutants, leading to reduced chromatin association and foci formation, both prerequisites for FANCD2-dependent MiDAS. Furthermore, K164 ubiquitination coordinates direct PCNA/FANCD2 colocalization in mitotic nuclei. Here, we show that PCNA K164 ubiquitination maintains human genome stability by promoting FANCD2-dependent MiDAS to prevent the accumulation of under-replicated DNA.
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Affiliation(s)
- Wendy Leung
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ryan M Baxley
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Emma Traband
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ya-Chu Chang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Colette B Rogers
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Liangjun Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Wesley Durrett
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kendall S Bromley
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA
| | - Lidia Fiedorowicz
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA
| | - Tanay Thakar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Anika Tella
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Alexandra Sobeck
- Institute for Human Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Eric A Hendrickson
- Department of Medicine, University of Virginia, Charlottesville, VA 22903, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Naoko Shima
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22903, USA.
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5
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Traband EL, Hammerlund SR, Shameem M, Narayan A, Ramana S, Tella A, Sobeck A, Shima N. Mitotic DNA Synthesis in Untransformed Human Cells Preserves Common Fragile Site Stability via a FANCD2-Driven Mechanism That Requires HELQ. J Mol Biol 2023; 435:168294. [PMID: 37777152 PMCID: PMC10839910 DOI: 10.1016/j.jmb.2023.168294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/14/2023] [Accepted: 09/25/2023] [Indexed: 10/02/2023]
Abstract
Faithful genome duplication is a challenging task for dividing mammalian cells, particularly under replication stress where timely resolution of late replication intermediates (LRIs) becomes crucial prior to cell division. In human cancer cells, mitotic DNA repair synthesis (MiDAS) is described as a final mechanism for the resolution of LRIs to avoid lethal chromosome mis-segregation. RAD52-driven MiDAS achieves this mission in part by generating gaps/breaks on metaphase chromosomes, which preferentially occur at common fragile sites (CFS). We previously demonstrated that a MiDAS mechanism also exists in untransformed and primary human cells, which is RAD52 independent but requires FANCD2. However, the properties of this form of MiDAS are not well understood. Here, we report that FANCD2-driven MiDAS in untransformed human cells: 1) requires a prerequisite step of FANCD2 mono-ubiquitination by a subset of Fanconi anemia (FA) proteins, 2) primarily acts to preserve CFS stability but not to prevent chromosome mis-segregation, and 3) depends on HELQ, which potentially functions at an early step. Hence, FANCD2-driven MiDAS in untransformed cells is built to protect CFS stability, whereas RAD52-driven MiDAS in cancer cells is likely adapted to prevent chromosome mis-segregation at the cost of CFS expression. Notably, we also identified a novel form of MiDAS, which surfaces to function when FANCD2 is absent in untransformed cells. Our findings substantiate the complex nature of MiDAS and a link between its deficiencies and the pathogenesis of FA, a human genetic disease.
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Affiliation(s)
- Emma L Traband
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Sarah R Hammerlund
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Mohammad Shameem
- Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Ananya Narayan
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Sanjiv Ramana
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Anika Tella
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
| | - Alexandra Sobeck
- Department of Biochemistry, Molecular Biology, and Biophysics, College of Biological Sciences, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, Minneapolis, MN 55455, USA
| | - Naoko Shima
- Department of Genetics, Cell Biology and Development, Medical School, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, Minneapolis, MN 55455, USA.
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6
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Osia B, Merkell A, Lopezcolorado FW, Ping X, Stark JM. RAD52 and ERCC6L/PICH have a compensatory relationship for genome stability in mitosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.23.554522. [PMID: 37662271 PMCID: PMC10473716 DOI: 10.1101/2023.08.23.554522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
The mammalian RAD52 protein is a DNA repair factor that has both strand annealing and recombination mediator activities, yet is dispensable for cell viability. To characterize genetic contexts that reveal dependence on RAD52 to sustain cell viability (i.e., synthetic lethal relationships), we performed genome-wide CRISPR knock-out screens. Subsequent secondary screening found that depletion of ERCC6L in RAD52-deficient cells causes reduced viability and elevated genome instability, measured as accumulation of 53BP1 into nuclear foci. Furthermore, loss of RAD52 causes elevated levels of anaphase ultrafine bridges marked by ERCC6L, and conversely depletion of ERCC6L causes elevated RAD52 foci both in prometaphase and interphase cells. These effects were enhanced with combination treatments using hydroxyurea and the topoisomerase IIα inhibitor ICRF-193, and the timing of these treatments are consistent with defects in addressing such stress in mitosis. Thus, loss of RAD52 appears to cause an increased reliance on ERCC6L in mitosis, and vice versa. Consistent with this notion, combined depletion of ERCC6L and disrupting G2/M progression via CDK1 inhibition causes a marked loss of viability in RAD52-deficient cells. We suggest that RAD52 and ERCC6L play compensatory roles in protecting genome stability in mitosis.
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7
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Yu Y, Xu W, Wen C, Zhao S, Li G, Liu R, Chen ZJ, Qin Y, Ma J, Yang Y, Zhao S. UBE2T resolves transcription-replication conflicts and protects common fragile sites in primordial germ cells. Cell Mol Life Sci 2023; 80:92. [PMID: 36928776 PMCID: PMC11072727 DOI: 10.1007/s00018-023-04733-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 02/04/2023] [Accepted: 02/22/2023] [Indexed: 03/18/2023]
Abstract
The proper development of primordial germ cells (PGCs) is an essential prerequisite for gametogenesis and mammalian fertility. The Fanconi anemia (FA) pathway functions in maintaining the development of PGCs. FANCT/UBE2T serves as an E2 ubiquitin-conjugating enzyme that ubiquitylates the FANCD2-FANCI complex to activate the FA pathway, but its role in the development of PGCs is not clear. In this study, we found that Ube2t knockout mice showed defects in PGC proliferation, leading to severe loss of germ cells after birth. Deletion of UBE2T exacerbated DNA damage and triggered the activation of the p53 pathway. We further demonstrated that UBE2T counteracted transcription-replication conflicts by resolving R-loops and stabilizing replication forks, and also protected common fragile sites by resolving R-loops in large genes and promoting mitotic DNA synthesis to maintain the genome stability of PGCs. Overall, these results provide new insights into the function and regulatory mechanisms of the FA pathway ensuring normal development of PGCs.
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Affiliation(s)
- Yongze Yu
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Weiwei Xu
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Canxin Wen
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Simin Zhao
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Guangyu Li
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Ran Liu
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Zi-Jiang Chen
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences, Jinan, 250021, Shandong, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, 200135, China
- Center for Reproductive Medicine, School of Medicine, Ren Ji Hospital, Shanghai Jiao Tong University, Shanghai, 200135, China
| | - Yingying Qin
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China
| | - Jinlong Ma
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China.
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China.
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China.
| | - Yajuan Yang
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China.
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China.
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China.
| | - Shidou Zhao
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, China.
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, Shandong, China.
- Shandong Key Laboratory of Reproductive Medicine, Jinan, 250012, Shandong, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, 250012, Shandong, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, 250012, Shandong, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, 250012, Shandong, China.
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8
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Mitotic DNA synthesis in response to replication stress requires the sequential action of DNA polymerases zeta and delta in human cells. Nat Commun 2023; 14:706. [PMID: 36759509 PMCID: PMC9911744 DOI: 10.1038/s41467-023-35992-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/11/2023] [Indexed: 02/11/2023] Open
Abstract
Oncogene activation creates DNA replication stress (RS) in cancer cells, which can generate under-replicated DNA regions (UDRs) that persist until cells enter mitosis. UDRs also have the potential to generate DNA bridges in anaphase cells or micronuclei in the daughter cells, which could promote genomic instability. To suppress such damaging changes to the genome, human cells have developed a strategy to conduct 'unscheduled' DNA synthesis in mitosis (termed MiDAS) that serves to rescue under-replicated loci. Previous studies have shown that MiDAS proceeds via a POLD3-dependent pathway that shows some features of break-induced replication. Here, we define how human cells utilize both DNA gap filling (REV1 and Pol ζ) and replicative (Pol δ) DNA polymerases to complete genome duplication following a perturbed S-phase. We present evidence for the existence of a polymerase-switch during MiDAS that is required for new DNA synthesis at UDRs. Moreover, we reveal that, upon oncogene activation, cancer cell survival is significantly compromised when REV1 is depleted, suggesting that REV1 inhibition might be a feasible approach for the treatment of some human cancers.
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9
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Barnes RP, Thosar SA, Opresko PL. Telomere Fragility and MiDAS: Managing the Gaps at the End of the Road. Genes (Basel) 2023; 14:genes14020348. [PMID: 36833275 PMCID: PMC9956152 DOI: 10.3390/genes14020348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/20/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Telomeres present inherent difficulties to the DNA replication machinery due to their repetitive sequence content, formation of non-B DNA secondary structures, and the presence of the nucleo-protein t-loop. Especially in cancer cells, telomeres are hot spots for replication stress, which can result in a visible phenotype in metaphase cells termed "telomere fragility". A mechanism cells employ to mitigate replication stress, including at telomeres, is DNA synthesis in mitosis (MiDAS). While these phenomena are both observed in mitotic cells, the relationship between them is poorly understood; however, a common link is DNA replication stress. In this review, we will summarize what is known to regulate telomere fragility and telomere MiDAS, paying special attention to the proteins which play a role in these telomere phenotypes.
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Affiliation(s)
- Ryan P. Barnes
- Department of Environmental and Occupational Health, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
- Correspondence: (R.P.B.); (P.L.O.)
| | - Sanjana A. Thosar
- Department of Environmental and Occupational Health, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
| | - Patricia L. Opresko
- Department of Environmental and Occupational Health, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Correspondence: (R.P.B.); (P.L.O.)
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10
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Said M, Barra V, Balzano E, Talhaoui I, Pelliccia F, Giunta S, Naim V. FANCD2 promotes mitotic rescue from transcription-mediated replication stress in SETX-deficient cancer cells. Commun Biol 2022; 5:1395. [PMID: 36543851 PMCID: PMC9772326 DOI: 10.1038/s42003-022-04360-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Replication stress (RS) is a leading cause of genome instability and cancer development. A substantial source of endogenous RS originates from the encounter between the transcription and replication machineries operating on the same DNA template. This occurs predominantly under specific contexts, such as oncogene activation, metabolic stress, or a deficiency in proteins that specifically act to prevent or resolve those transcription-replication conflicts (TRCs). One such protein is Senataxin (SETX), an RNA:DNA helicase involved in resolution of TRCs and R-loops. Here we identify a synthetic lethal interaction between SETX and proteins of the Fanconi anemia (FA) pathway. Depletion of SETX induces spontaneous under-replication and chromosome fragility due to active transcription and R-loops that persist in mitosis. These fragile loci are targeted by the Fanconi anemia protein, FANCD2, to facilitate the resolution of under-replicated DNA, thus preventing chromosome mis-segregation and allowing cells to proliferate. Mechanistically, we show that FANCD2 promotes mitotic DNA synthesis that is dependent on XPF and MUS81 endonucleases. Importantly, co-depleting FANCD2 together with SETX impairs cancer cell proliferation, without significantly affecting non-cancerous cells. Therefore, we uncovered a synthetic lethality between SETX and FA proteins for tolerance of transcription-mediated RS that may be exploited for cancer therapy.
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Affiliation(s)
- Maha Said
- grid.14925.3b0000 0001 2284 9388CNRS UMR9019, Université Paris-Saclay, Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Viviana Barra
- grid.10776.370000 0004 1762 5517Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Elisa Balzano
- grid.7841.aDepartment of Biology & Biotechnology “Charles Darwin”, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Ibtissam Talhaoui
- grid.14925.3b0000 0001 2284 9388CNRS UMR9019, Université Paris-Saclay, Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Franca Pelliccia
- grid.7841.aDepartment of Biology & Biotechnology “Charles Darwin”, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Simona Giunta
- grid.7841.aDepartment of Biology & Biotechnology “Charles Darwin”, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Valeria Naim
- grid.14925.3b0000 0001 2284 9388CNRS UMR9019, Université Paris-Saclay, Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
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11
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Bhat DS, Spies MA, Spies M. A moving target for drug discovery: Structure activity relationship and many genome (de)stabilizing functions of the RAD52 protein. DNA Repair (Amst) 2022; 120:103421. [PMID: 36327799 PMCID: PMC9888176 DOI: 10.1016/j.dnarep.2022.103421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/18/2022] [Accepted: 10/24/2022] [Indexed: 02/02/2023]
Abstract
BRCA-ness phenotype, a signature of many breast and ovarian cancers, manifests as deficiency in homologous recombination, and as defects in protection and repair of damaged DNA replication forks. A dependence of such cancers on DNA repair factors less important for survival of BRCA-proficient cells, offers opportunities for development of novel chemotherapeutic interventions. The first drugs targeting BRCA-deficient cancers, poly-ADP-ribose polymerase (PARP) inhibitors have been approved for the treatment of advanced, chemotherapy resistant cancers in patients with BRCA1/2 germline mutations. Nine additional proteins that can be targeted to selectively kill BRCA-deficient cancer cells have been identified. Among them, a DNA repair protein RAD52 is an especially attractive target due to general tolerance of the RAD52 loss of function, and protective role of an inactivating mutation. Yet, the effective pharmacological inhibitors of RAD52 have not been forthcoming. In this review, we discuss advances in the state of our knowledge of the RAD52 structure, activities and cellular functions, with a specific focus on the features that make RAD52 an attractive, but difficult drug target.
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Affiliation(s)
- Divya S Bhat
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA; Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA.
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12
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Hassani MA, Murid J, Yan J. Regulator of telomere elongation helicase 1 gene and its association with malignancy. Cancer Rep (Hoboken) 2022; 6:e1735. [PMID: 36253342 PMCID: PMC9875622 DOI: 10.1002/cnr2.1735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND With the progression of next-generation sequencing technologies, researchers have identified numerous variants of the regulator of telomere elongation helicase 1 (RTEL1) gene that are associated with a broad spectrum of phenotypic manifestations, including malignancies. At the molecular level, RTEL1 is involved in the regulation of the repair, replication, and transcription of deoxyribonucleic acid (DNA) and the maintenance of telomere length. RTEL1 can act both as a promotor and inhibitor of tumorigenesis. Here, we review the potential mechanisms implicated in the malignant transformation of tissues under conditions of RTEL1 deficiency or its aberrant overexpression. RECENT FINDINGS A major hemostatic challenge during RTEL1 dysfunction could arise from its unbalanced activity for unwinding guanine-rich quadruplex DNA (G4-DNA) structures. In contrast, RTEL1 deficiency leads to alterations in telomeric and genome-wide DNA maintenance mechanisms, ribonucleoprotein metabolism, and the creation of an inflammatory and immune-deficient microenvironment, all promoting malignancy. Additionally, we hypothesize that functionally similar molecules could act to compensate for the deteriorated functions of RTEL1, thereby facilitating the survival of malignant cells. On the contrary, RTEL1 over-expression was directed toward G4-unwinding, by promoting replication fork progression and maintaining intact telomeres, may facilitate malignant transformation and proliferation of various pre-malignant cellular compartments. CONCLUSIONS Therefore, restoring the equilibrium of RTEL1 functions could serve as a therapeutic approach for preventing and treating malignancies.
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Affiliation(s)
- Mohammad Arian Hassani
- Department of Hematology, Liaoning Medical Center for Hematopoietic Stem Cell Transplantation, Liaoning Key Laboratory of Hematopoietic Stem Cell Transplantation and Translational Medicine, Dalian Key Laboratory of HematologySecond Hospital of Dalian Medical UniversityDalianChina,Department of Hematology, Endocrinology and Rheumatology, Ali Abad Teaching HospitalKabul University of Medical SciencesJamal menaKabulAfghanistan
| | - Jamshid Murid
- Department of Hematology, Endocrinology and Rheumatology, Ali Abad Teaching HospitalKabul University of Medical SciencesJamal menaKabulAfghanistan
| | - Jinsong Yan
- Department of Hematology, Liaoning Medical Center for Hematopoietic Stem Cell Transplantation, Liaoning Key Laboratory of Hematopoietic Stem Cell Transplantation and Translational Medicine, Dalian Key Laboratory of HematologySecond Hospital of Dalian Medical UniversityDalianChina,Diamond Bay Institute of HematologySecond Hospital of Dalian Medical UniversityDalianChina
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13
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Processing DNA lesions during mitosis to prevent genomic instability. Biochem Soc Trans 2022; 50:1105-1118. [PMID: 36040211 PMCID: PMC9444068 DOI: 10.1042/bst20220049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 11/17/2022]
Abstract
Failure of cells to process toxic double-strand breaks (DSBs) constitutes a major intrinsic source of genome instability, a hallmark of cancer. In contrast with interphase of the cell cycle, canonical repair pathways in response to DSBs are inactivated in mitosis. Although cell cycle checkpoints prevent transmission of DNA lesions into mitosis under physiological condition, cancer cells frequently display mitotic DNA lesions. In this review, we aim to provide an overview of how mitotic cells process lesions that escape checkpoint surveillance. We outline mechanisms that regulate the mitotic DNA damage response and the different types of lesions that are carried over to mitosis, with a focus on joint DNA molecules arising from under-replication and persistent recombination intermediates, as well as DNA catenanes. Additionally, we discuss the processing pathways that resolve each of these lesions in mitosis. Finally, we address the acute and long-term consequences of unresolved mitotic lesions on cellular fate and genome stability.
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14
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Brenner KA, Nandakumar J. Consequences of telomere replication failure: the other end-replication problem. Trends Biochem Sci 2022; 47:506-517. [PMID: 35440402 PMCID: PMC9106919 DOI: 10.1016/j.tibs.2022.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/28/2022] [Accepted: 03/17/2022] [Indexed: 01/14/2023]
Abstract
Telomeres are chromosome-capping structures that protect ends of the linear genome from DNA damage sensors. However, these structures present obstacles during DNA replication. Incomplete telomere replication accelerates telomere shortening and limits replicative lifespan. Therefore, continued proliferation under conditions of replication stress requires a means of telomere repair, particularly in the absence of telomerase. It was recently revealed that replication stress triggers break-induced replication (BIR) and mitotic DNA synthesis (MiDAS) at mammalian telomeres; however, these mechanisms are error prone and primarily utilized in tumorigenic contexts. In this review article, we discuss the consequences of replication stress at telomeres and how use of available repair pathways contributes to genomic instability. Current research suggests that fragile telomeres are ultimately tumor-suppressive and thus may be better left unrepaired.
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Affiliation(s)
- Kirsten A Brenner
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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15
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DNA replication is highly resilient and persistent under the challenge of mild replication stress. Cell Rep 2022; 39:110701. [PMID: 35443178 PMCID: PMC9226383 DOI: 10.1016/j.celrep.2022.110701] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 12/21/2021] [Accepted: 03/28/2022] [Indexed: 12/25/2022] Open
Abstract
Mitotic DNA synthesis (MiDAS) has been proposed to restart DNA synthesis during mitosis because of replication fork stalling in late interphase caused by mild replication stress (RS). Contrary to this proposal, we find that cells exposed to mild RS in fact maintain continued DNA replication throughout G2 and during G2-M transition in RAD51- and RAD52-dependent manners. Persistent DNA synthesis is necessary to resolve replication intermediates accumulated in G2 and disengage an ATR-imposed block to mitotic entry. Because of its continual nature, DNA synthesis at very late replication sites can overlap with chromosome condensation, generating the phenomenon of mitotic DNA synthesis. Unexpectedly, we find that the commonly used CDK1 inhibitor RO3306 interferes with replication to preclude detection of G2 DNA synthesis, leading to the impression of a mitosis-driven response. Our study reveals the importance of persistent DNA replication and checkpoint control to lessen the risk for severe genome under-replication under mild RS. DNA synthesis persists during G2-M transition to counteract replication stress (RS) RAD51/RAD52-mediated HR pathways facilitate the continuation of G2-M DNA synthesis Continued G2 DNA synthesis relieves RS-induced G2/M checkpoint for mitotic entry RO3306, but not CDK1 inhibition, non-specifically interferes with DNA synthesis
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16
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Li JN, Wang MY, Chen YT, Kuo YL, Chen PS. Expression of SnoRNA U50A Is Associated with Better Prognosis and Prolonged Mitosis in Breast Cancer. Cancers (Basel) 2021; 13:cancers13246304. [PMID: 34944924 PMCID: PMC8699759 DOI: 10.3390/cancers13246304] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/22/2021] [Accepted: 11/26/2021] [Indexed: 11/24/2022] Open
Abstract
Simple Summary SnoRNAs are essential for fundamental cellular processes. However, emerging evidence shows that snoRNAs play regulatory roles during cancer progression. The snoRNA U50A (U50A) is a newly-identified putative tumor suppressor, but its clinical and mechanistic impacts in breast cancer remain elusive. In this study, we quantified the copy number of U50A in breast cancer patient tissues and found that a higher level of U50A expression is correlated with better overall survival in breast cancer patients. By utilizing transcriptomic analysis, we demonstrated that U50A prolongs mitosis and reduces colony-forming ability through downregulating mitosis-related genes. Consistent with these in vitro results, breast cancer tissues expressing higher U50A significantly exhibited accumulated mitotic tumor cells and were associated with reduced tumor size. Altogether, this is the first study showing the clinical, cellular, and regulatory impacts of snoRNA U50A in human breast cancer. Abstract Small nucleolar RNAs (snoRNAs) are small noncoding RNAs generally recognized as housekeeping genes. Genomic analysis has shown that snoRNA U50A (U50A) is a candidate tumor suppressor gene deleted in less than 10% of breast cancer patients. To date, the pathological roles of U50A in cancer, including its clinical significance and its regulatory impact at the molecular level, are not well-defined. Here, we quantified the copy number of U50A in human breast cancer tissues. Our results showed that the U50A expression level is correlated with better prognosis in breast cancer patients. Utilizing RNA-sequencing for transcriptomic analysis, we revealed that U50A downregulates mitosis-related genes leading to arrested cancer cell mitosis and suppressed colony-forming ability. Moreover, in support of the impacts of U50A in prolonging mitosis and inhibiting clonogenic activity, breast cancer tissues with higher U50A expression exhibit accumulated mitotic tumor cells. In conclusion, based on the evidence from U50A-downregulated mitosis-related genes, prolonged mitosis, repressed colony-forming ability, and clinical analyses, we demonstrated molecular insights into the pathological impact of snoRNA U50A in human breast cancer.
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Affiliation(s)
- Jie-Ning Li
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
| | - Ming-Yang Wang
- Department of Surgery, National Taiwan University Hospital, Taipei 100, Taiwan;
| | - Yi-Ting Chen
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
- Department of Medicine, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Yao-Lung Kuo
- Department of Surgery, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
- Breast Medical Center, National Cheng Kung University Hospital, Tainan 701, Taiwan
- Correspondence: (Y.-L.K.); or (P.-S.C.); Tel.: +886-6-2353535 (ext. 5224) (Y.-L.K.); +886-6-2353535 (ext. 6233) (P.-S.C.); Fax: +886-6-2368549 (Y.-L.K.); +886-6-2363956 (P.-S.C.)
| | - Pai-Sheng Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
- Correspondence: (Y.-L.K.); or (P.-S.C.); Tel.: +886-6-2353535 (ext. 5224) (Y.-L.K.); +886-6-2353535 (ext. 6233) (P.-S.C.); Fax: +886-6-2368549 (Y.-L.K.); +886-6-2363956 (P.-S.C.)
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17
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Abstract
Unlike bacteria, mammalian cells need to complete DNA replication before segregating their chromosomes for the maintenance of genome integrity. Thus, cells have evolved efficient pathways to restore stalled and/or collapsed replication forks during S-phase, and when necessary, also to delay cell cycle progression to ensure replication completion. However, strong evidence shows that cells can proceed to mitosis with incompletely replicated DNA when under mild replication stress (RS) conditions. Consequently, the incompletely replicated genomic gaps form, predominantly at common fragile site regions, where the converging fork-like DNA structures accumulate. These branched structures pose a severe threat to the faithful disjunction of chromosomes as they physically interlink the partially duplicated sister chromatids. In this review, we provide an overview discussing how cells respond and deal with the under-replicated DNA structures that escape from the S/G2 surveillance system. We also focus on recent research of a mitotic break-induced replication pathway (also known as mitotic DNA repair synthesis), which has been proposed to operate during prophase in an attempt to finish DNA synthesis at the under-replicated genomic regions. Finally, we discuss recent data on how mild RS may cause chromosome instability and mutations that accelerate cancer genome evolution.
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Affiliation(s)
- Camelia Mocanu
- Chromosome Dynamics and Stability Group, Genome Damage and Stability Centre, University of Sussex, Brighton BN1 7BG, UK
| | - Kok-Lung Chan
- Chromosome Dynamics and Stability Group, Genome Damage and Stability Centre, University of Sussex, Brighton BN1 7BG, UK
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18
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Atkins A, Xu MJ, Li M, Rogers NP, Pryzhkova MV, Jordan PW. SMC5/6 is required for replication fork stability and faithful chromosome segregation during neurogenesis. eLife 2020; 9:e61171. [PMID: 33200984 PMCID: PMC7723410 DOI: 10.7554/elife.61171] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/16/2020] [Indexed: 12/21/2022] Open
Abstract
Mutations of SMC5/6 components cause developmental defects, including primary microcephaly. To model neurodevelopmental defects, we engineered a mouse wherein Smc5 is conditionally knocked out (cKO) in the developing neocortex. Smc5 cKO mice exhibited neurodevelopmental defects due to neural progenitor cell (NPC) apoptosis, which led to reduction in cortical layer neurons. Smc5 cKO NPCs formed DNA bridges during mitosis and underwent chromosome missegregation. SMC5/6 depletion triggers a CHEK2-p53 DNA damage response, as concomitant deletion of the Trp53 tumor suppressor or Chek2 DNA damage checkpoint kinase rescued Smc5 cKO neurodevelopmental defects. Further assessment using Smc5 cKO and auxin-inducible degron systems demonstrated that absence of SMC5/6 leads to DNA replication stress at late-replicating regions such as pericentromeric heterochromatin. In summary, SMC5/6 is important for completion of DNA replication prior to entering mitosis, which ensures accurate chromosome segregation. Thus, SMC5/6 functions are critical in highly proliferative stem cells during organism development.
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Affiliation(s)
- Alisa Atkins
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Michelle J Xu
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Maggie Li
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Nathaniel P Rogers
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Marina V Pryzhkova
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Philip W Jordan
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
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19
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Macheret M, Bhowmick R, Sobkowiak K, Padayachy L, Mailler J, Hickson ID, Halazonetis TD. High-resolution mapping of mitotic DNA synthesis regions and common fragile sites in the human genome through direct sequencing. Cell Res 2020; 30:997-1008. [PMID: 32561860 PMCID: PMC7784693 DOI: 10.1038/s41422-020-0358-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/31/2020] [Indexed: 12/22/2022] Open
Abstract
DNA replication stress, a feature of human cancers, often leads to instability at specific genomic loci, such as the common fragile sites (CFSs). Cells experiencing DNA replication stress may also exhibit mitotic DNA synthesis (MiDAS). To understand the physiological function of MiDAS and its relationship to CFSs, we mapped, at high resolution, the genomic sites of MiDAS in cells treated with the DNA polymerase inhibitor aphidicolin. Sites of MiDAS were evident as well-defined peaks that were largely conserved between cell lines and encompassed all known CFSs. The MiDAS peaks mapped within large, transcribed, origin-poor genomic regions. In cells that had been treated with aphidicolin, these regions remained unreplicated even in late S phase; MiDAS then served to complete their replication after the cells entered mitosis. Interestingly, leading and lagging strand synthesis were uncoupled in MiDAS, consistent with MiDAS being a form of break-induced replication, a repair mechanism for collapsed DNA replication forks. Our results provide a better understanding of the mechanisms leading to genomic instability at CFSs and in cancer cells.
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Affiliation(s)
- Morgane Macheret
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Rahul Bhowmick
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Katarzyna Sobkowiak
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Laura Padayachy
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Jonathan Mailler
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark.
| | - Thanos D Halazonetis
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland.
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20
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Under-Replicated DNA: The Byproduct of Large Genomes? Cancers (Basel) 2020; 12:cancers12102764. [PMID: 32992928 PMCID: PMC7601121 DOI: 10.3390/cancers12102764] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 12/28/2022] Open
Abstract
In this review, we provide an overview of how proliferating eukaryotic cells overcome one of the main threats to genome stability: incomplete genomic DNA replication during S phase. We discuss why it is currently accepted that double fork stalling (DFS) events are unavoidable events in higher eukaryotes with large genomes and which responses have evolved to cope with its main consequence: the presence of under-replicated DNA (UR-DNA) outside S phase. Particular emphasis is placed on the processes that constrain the detrimental effects of UR-DNA. We discuss how mitotic DNA synthesis (MiDAS), mitotic end joining events and 53BP1 nuclear bodies (53BP1-NBs) deal with such specific S phase DNA replication remnants during the subsequent phases of the cell cycle.
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