Pub Date : 2025-10-08DOI: 10.1016/j.dnarep.2025.103902
Joshua L. Turner, Georgia Moore, Tyler J. McCraw, Jennifer M. Mason
Homologous recombination proteins maintain genome stability by repairing double strand breaks and protecting replication fork stability. Defects in homologous recombination results in cancer predisposition but can be exploited due to increased sensitivity to certain chemotherapeutics such as PARP inhibitors. The NEK8 kinase has roles in the replication response and homologous recombination. NEK8 is overexpressed in breast cancer, but the impact of NEK8 overexpression on homologous recombination has not been determined. Here, we demonstrate NEK8 overexpression inhibits RAD51 focus formation resulting in a defect in homologous recombination and degradation of stalled replication forks. Importantly, NEK8 overexpression sensitizes cells to the PARP inhibitor, Olaparib. Together, our results suggest NEK8 overexpressing tumors may be recombination-deficient and respond to chemotherapeutics that target defects in recombination such as Olaparib.
{"title":"Overexpression of the NEK8 kinase inhibits homologous recombination","authors":"Joshua L. Turner, Georgia Moore, Tyler J. McCraw, Jennifer M. Mason","doi":"10.1016/j.dnarep.2025.103902","DOIUrl":"10.1016/j.dnarep.2025.103902","url":null,"abstract":"<div><div>Homologous recombination proteins maintain genome stability by repairing double strand breaks and protecting replication fork stability. Defects in homologous recombination results in cancer predisposition but can be exploited due to increased sensitivity to certain chemotherapeutics such as PARP inhibitors. The NEK8 kinase has roles in the replication response and homologous recombination. NEK8 is overexpressed in breast cancer, but the impact of NEK8 overexpression on homologous recombination has not been determined. Here, we demonstrate NEK8 overexpression inhibits RAD51 focus formation resulting in a defect in homologous recombination and degradation of stalled replication forks. Importantly, NEK8 overexpression sensitizes cells to the PARP inhibitor, Olaparib. Together, our results suggest NEK8 overexpressing tumors may be recombination-deficient and respond to chemotherapeutics that target defects in recombination such as Olaparib.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"155 ","pages":"Article 103902"},"PeriodicalIF":2.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.dnarep.2025.103900
James Eduardo Lago Londero , Rayana dos Santos Feltrin , Ana Lucia Anversa Segatto , André Passaglia Schuch
The UV-sensitivity hypothesis for amphibian decline proposes that interspecific variation in cyclobutane pyrimidine dimer (CPD) photolyase activity determines species’ UV sensitivity, which is linked to their natural history and population trends. Here, to shed light on the molecular basis of UV resistance variation, we investigated the evolutionary dynamics of CPD photolyases in amphibians focusing on regions and sites relevant to protein function. Our evolutionary analyses revealed that amino acids critical for CPD photolyase function are highly conserved and their codons have been evolving under purifying selection. Three tryptophan residues, critical for light-dependent repair and potentially for dark repair, are highly conserved in CPD photolyases across species. Nevertheless, we identified variations in functionally relevant CPD photolyase amino acids across amphibian clades, some of which are predicted to contract the active site and destabilize the protein structure. Caudata CPD photolyases contain functionally relevant variations likely linked to the high UV sensitivity of salamanders and newts. In Gymnophiona, we found relaxed purifying selection in CPD photolyase codons, as well as functionally relevant amino acid variations, likely reflecting the fossorial, dark-dwelling lifestyle of caecilians. Strikingly, most amphibian species with decreasing populations exhibit CPD photolyases with functionally relevant amino acid variations, and this pattern is even stronger for variations that disrupt protein structure. For example, two structurally disruptive, functionally relevant amino acid variations co-occur in CPD photolyases of species from the genera Bombina (Anura) and Ambystoma (Caudata), most of which exhibit declining populations. This study shows that species-specific differences in CPD photolyases underscore the UV-sensitivity hypothesis in amphibian ecology and conservation.
{"title":"CPD photolyase evolution supports amphibian UV-sensitivity hypothesis","authors":"James Eduardo Lago Londero , Rayana dos Santos Feltrin , Ana Lucia Anversa Segatto , André Passaglia Schuch","doi":"10.1016/j.dnarep.2025.103900","DOIUrl":"10.1016/j.dnarep.2025.103900","url":null,"abstract":"<div><div>The UV-sensitivity hypothesis for amphibian decline proposes that interspecific variation in cyclobutane pyrimidine dimer (CPD) photolyase activity determines species’ UV sensitivity, which is linked to their natural history and population trends. Here, to shed light on the molecular basis of UV resistance variation, we investigated the evolutionary dynamics of CPD photolyases in amphibians focusing on regions and sites relevant to protein function. Our evolutionary analyses revealed that amino acids critical for CPD photolyase function are highly conserved and their codons have been evolving under purifying selection. Three tryptophan residues, critical for light-dependent repair and potentially for dark repair, are highly conserved in CPD photolyases across species. Nevertheless, we identified variations in functionally relevant CPD photolyase amino acids across amphibian clades, some of which are predicted to contract the active site and destabilize the protein structure. Caudata CPD photolyases contain functionally relevant variations likely linked to the high UV sensitivity of salamanders and newts. In Gymnophiona, we found relaxed purifying selection in CPD photolyase codons, as well as functionally relevant amino acid variations, likely reflecting the fossorial, dark-dwelling lifestyle of caecilians. Strikingly, most amphibian species with decreasing populations exhibit CPD photolyases with functionally relevant amino acid variations, and this pattern is even stronger for variations that disrupt protein structure. For example, two structurally disruptive, functionally relevant amino acid variations co-occur in CPD photolyases of species from the genera <em>Bombina</em> (Anura) and <em>Ambystoma</em> (Caudata), most of which exhibit declining populations. This study shows that species-specific differences in CPD photolyases underscore the UV-sensitivity hypothesis in amphibian ecology and conservation.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"154 ","pages":"Article 103900"},"PeriodicalIF":2.7,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.dnarep.2025.103899
Xingkai He , Feng Chen , Linmin Zhou , Yuanqing Sun , Qi Liu , Weicheng Chen , Luyao Zhu , Jun Zhang , Wei-Guo Zhu
The comet assay has evolved into a high-resolution, multifunctional technique for evaluating DNA damage, repair capacity, and epigenetic modifications. Over the past fifteen years, significant advancements-including the enzyme-modified comet assays (EMCA), Comet-FISH, and high-throughput platforms have substantially expanded its analytical capabilities. Specialized formats like the Flash comet assay and the BrdU comet assay further enhance the discrimination of DNA strand break types and replication-associated damage. Despite these innovations, issues related to standardization, reproducibility, and inter-laboratory consistency remain. Initiatives such as the Minimum Information for Reporting Comet Assay (MIRCA) guidelines, alongside the integration of automated imaging and machine learning, are being implemented to address these challenges. With its growing applications in environmental toxicology, biomonitoring, and clinical research, the comet assay is increasingly recognized as a key tool in precision toxicology and personalized medicine. This review highlights major technical developments and emerging applications of the comet assay over the past fifteen years, discusses sources of experimental variability and strategies for optimization, and provides an update on current laboratory protocols for assessing DNA damage induced by genotoxic agents.
彗星分析已经发展成为一种高分辨率、多功能的技术，用于评估DNA损伤、修复能力和表观遗传修饰。在过去的15年里，包括酶修饰彗星测定法（EMCA）、comet - fish和高通量平台在内的重大进步大大扩展了其分析能力。Flash彗星分析和BrdU彗星分析等专门格式进一步增强了DNA链断裂类型和复制相关损伤的区分。尽管有这些创新，与标准化、可重复性和实验室间一致性相关的问题仍然存在。为了应对这些挑战，正在实施诸如报告彗星分析（MIRCA）指南的最低信息（Minimum Information for Reporting Comet Assay）以及自动化成像和机器学习的集成等举措。随着彗星分析在环境毒理学、生物监测和临床研究中的应用越来越广泛，彗星分析越来越被认为是精确毒理学和个性化医疗的关键工具。本综述重点介绍了过去15年来彗星分析的主要技术发展和新兴应用，讨论了实验变异性的来源和优化策略，并提供了评估遗传毒性物质诱导的DNA损伤的当前实验室方案的更新。
{"title":"The comet assay: A contemporary approach for detecting genomic instability","authors":"Xingkai He , Feng Chen , Linmin Zhou , Yuanqing Sun , Qi Liu , Weicheng Chen , Luyao Zhu , Jun Zhang , Wei-Guo Zhu","doi":"10.1016/j.dnarep.2025.103899","DOIUrl":"10.1016/j.dnarep.2025.103899","url":null,"abstract":"<div><div>The comet assay has evolved into a high-resolution, multifunctional technique for evaluating DNA damage, repair capacity, and epigenetic modifications. Over the past fifteen years, significant advancements-including the enzyme-modified comet assays (EMCA), Comet-FISH, and high-throughput platforms have substantially expanded its analytical capabilities. Specialized formats like the Flash comet assay and the BrdU comet assay further enhance the discrimination of DNA strand break types and replication-associated damage. Despite these innovations, issues related to standardization, reproducibility, and inter-laboratory consistency remain. Initiatives such as the Minimum Information for Reporting Comet Assay (MIRCA) guidelines, alongside the integration of automated imaging and machine learning, are being implemented to address these challenges. With its growing applications in environmental toxicology, biomonitoring, and clinical research, the comet assay is increasingly recognized as a key tool in precision toxicology and personalized medicine. This review highlights major technical developments and emerging applications of the comet assay over the past fifteen years, discusses sources of experimental variability and strategies for optimization, and provides an update on current laboratory protocols for assessing DNA damage induced by genotoxic agents.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"154 ","pages":"Article 103899"},"PeriodicalIF":2.7,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145214977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.dnarep.2025.103898
Marie-France Langelier, John M. Pascal
Poly(ADP-ribose) or PAR is a versatile signaling molecule with a broad impact on human biology. PAR is a prominent indicator of cellular DNA damage and genomic transactions such as replication and transcription. Canonically, human PARP enzymes create PAR as a modification on proteins. Recently, PARP enzymes were found to create free PAR molecules that are not attached to protein. Free PAR has been implicated in cell death signaling, but the production of free PAR was assumed to be generated by glycohydrolases breaking down protein-linked PAR into smaller fragments. The direct de novo production of free PAR by PARP1 occurs alongside the synthesis of protein-linked PAR in response to DNA damage, suggesting a more prevalent role for free PAR in DNA damage signaling. This review outlines the discovery of free PAR synthesis in biochemical reactions and in cellular models of the DNA damage response. The implications for this finding are summarized in the context of DNA damage signaling and associated processes of biomolecular condensate formation and Parthanatos cell death signaling.
{"title":"PARP enzyme synthesis of protein-free poly(ADP-ribose): Implications for DNA damage signaling and repair","authors":"Marie-France Langelier, John M. Pascal","doi":"10.1016/j.dnarep.2025.103898","DOIUrl":"10.1016/j.dnarep.2025.103898","url":null,"abstract":"<div><div>Poly(ADP-ribose) or PAR is a versatile signaling molecule with a broad impact on human biology. PAR is a prominent indicator of cellular DNA damage and genomic transactions such as replication and transcription. Canonically, human PARP enzymes create PAR as a modification on proteins. Recently, PARP enzymes were found to create free PAR molecules that are not attached to protein. Free PAR has been implicated in cell death signaling, but the production of free PAR was assumed to be generated by glycohydrolases breaking down protein-linked PAR into smaller fragments. The direct de novo production of free PAR by PARP1 occurs alongside the synthesis of protein-linked PAR in response to DNA damage, suggesting a more prevalent role for free PAR in DNA damage signaling. This review outlines the discovery of free PAR synthesis in biochemical reactions and in cellular models of the DNA damage response. The implications for this finding are summarized in the context of DNA damage signaling and associated processes of biomolecular condensate formation and Parthanatos cell death signaling.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"154 ","pages":"Article 103898"},"PeriodicalIF":2.7,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.dnarep.2025.103901
Qin Hu , Kewu Wang , Chuanrong Chen , Jian Ding , Yang He , Zhaoning Ji
Background
Triple-negative breast cancer (TNBC), characterized by its aggressiveness, constitutes a unique breast cancer subtype, lacking effective targeted therapies. Its progression is often driven by cell cycle control dysfunction, impaired DNA damage handling, and resistance to apoptosis. Ubiquitin-conjugating enzyme E2C (UBE2C), an essential mitotic regulator, has been implicated in tumorigenesis and therapy resistance in several tumor types, but its relevance in TNBC is still poorly understood. This study focused on investigating the expression and functional importance of UBE2C in TNBC development.
Methods
UBE2C levels and their clinical relevance in TNBC were evaluated via transcriptomic data from TCGA and GTEx. Gene set enrichment analysis (GSEA) was performed to pinpoint UBE2C-associated biological pathways. Functional validation was conducted in MDA-MB-231 TNBC cell lines via qRT-PCR, Western blotting, flow cytometry, comet assay, and TUNEL staining to examine the effects of UBE2C modulation on cell cycle dynamics, DNA damage response, and apoptosis.
Results
UBE2C exhibited marked overexpression in TNBC tissues and cell lines relative to normal controls (P < 0.01), and its high expression was correlated with reduced overall survival (P = 0.01). GSEA indicated enrichment of cell cycle and DNA repair pathways in UBE2C-high samples, while apoptosis pathways were suppressed (FDR < 0.25). Functional assays demonstrated that UBE2C overexpression accelerated G1/S and G2/M transitions (P < 0.01), reduced DNA damage accumulation (P < 0.01), and suppressed apoptotic processes (P < 0.01), while UBE2C knockdown elicited the opposite effects.
Conclusion
UBE2C promotes TNBC cell survival through modulation of cell cycle progression, DNA repair mechanisms, and apoptosis signaling. These results suggested that UBE2C could be considered a promising biomarker and therapeutic target, particularly in combination with DNA-damaging agents for personalized TNBC therapy.
{"title":"UBE2C promotes cell cycle progression and suppresses DNA damage-induced apoptosis in triple-negative breast cancer","authors":"Qin Hu , Kewu Wang , Chuanrong Chen , Jian Ding , Yang He , Zhaoning Ji","doi":"10.1016/j.dnarep.2025.103901","DOIUrl":"10.1016/j.dnarep.2025.103901","url":null,"abstract":"<div><h3>Background</h3><div>Triple-negative breast cancer (TNBC), characterized by its aggressiveness, constitutes a unique breast cancer subtype, lacking effective targeted therapies. Its progression is often driven by cell cycle control dysfunction, impaired DNA damage handling, and resistance to apoptosis. Ubiquitin-conjugating enzyme E2C (UBE2C), an essential mitotic regulator, has been implicated in tumorigenesis and therapy resistance in several tumor types, but its relevance in TNBC is still poorly understood. This study focused on investigating the expression and functional importance of UBE2C in TNBC development.</div></div><div><h3>Methods</h3><div>UBE2C levels and their clinical relevance in TNBC were evaluated via transcriptomic data from TCGA and GTEx. Gene set enrichment analysis (GSEA) was performed to pinpoint UBE2C-associated biological pathways. Functional validation was conducted in MDA-MB-231 TNBC cell lines via qRT-PCR, Western blotting, flow cytometry, comet assay, and TUNEL staining to examine the effects of UBE2C modulation on cell cycle dynamics, DNA damage response, and apoptosis.</div></div><div><h3>Results</h3><div>UBE2C exhibited marked overexpression in TNBC tissues and cell lines relative to normal controls (P < 0.01), and its high expression was correlated with reduced overall survival (P = 0.01). GSEA indicated enrichment of cell cycle and DNA repair pathways in UBE2C-high samples, while apoptosis pathways were suppressed (FDR < 0.25). Functional assays demonstrated that UBE2C overexpression accelerated G1/S and G2/M transitions (P < 0.01), reduced DNA damage accumulation (P < 0.01), and suppressed apoptotic processes (P < 0.01), while UBE2C knockdown elicited the opposite effects.</div></div><div><h3>Conclusion</h3><div>UBE2C promotes TNBC cell survival through modulation of cell cycle progression, DNA repair mechanisms, and apoptosis signaling. These results suggested that UBE2C could be considered a promising biomarker and therapeutic target, particularly in combination with DNA-damaging agents for personalized TNBC therapy.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"154 ","pages":"Article 103901"},"PeriodicalIF":2.7,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145294840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eukaryotic cells organize their genomic DNA into chromatin to achieve both compact packaging and precise regulation of essential processes, including DNA repair. Depending on the type of damage, distinct repair pathways are activated through the targeted recruitment of repair factors to chromatin. RAD51 is the central recombinase in homologous recombination (HR) and forms nucleoprotein filaments, but its mode of chromatin engagement has remained elusive. In this review, we summarize recent progress in the structural and biochemical understanding of DNA repair within chromatin, with a particular focus on RAD51 and its role in HR. Specifically, we review newly determined cryo-electron microscopy (cryo-EM) structures of RAD51 bound to nucleosomes, revealing how RAD51 assembles on chromatin, recognizes DNA damage sites, and remodels nucleosomes into filamentous intermediates. We summarize current insights into how HR-associated proteins regulate RAD51 activity on chromatin, ensuring the fidelity of each step in HR. We conclude by outlining future directions for elucidating the downstream mechanisms of RAD51-mediated HR in the chromatin context.
{"title":"Mechanistic insights into RAD51-mediated nucleosome binding and remodeling in homologous recombination","authors":"Takuro Shioi , Suguru Hatazawa , Yoshimasa Takizawa , Hitoshi Kurumizaka","doi":"10.1016/j.dnarep.2025.103891","DOIUrl":"10.1016/j.dnarep.2025.103891","url":null,"abstract":"<div><div>Eukaryotic cells organize their genomic DNA into chromatin to achieve both compact packaging and precise regulation of essential processes, including DNA repair. Depending on the type of damage, distinct repair pathways are activated through the targeted recruitment of repair factors to chromatin. RAD51 is the central recombinase in homologous recombination (HR) and forms nucleoprotein filaments, but its mode of chromatin engagement has remained elusive. In this review, we summarize recent progress in the structural and biochemical understanding of DNA repair within chromatin, with a particular focus on RAD51 and its role in HR. Specifically, we review newly determined cryo-electron microscopy (cryo-EM) structures of RAD51 bound to nucleosomes, revealing how RAD51 assembles on chromatin, recognizes DNA damage sites, and remodels nucleosomes into filamentous intermediates. We summarize current insights into how HR-associated proteins regulate RAD51 activity on chromatin, ensuring the fidelity of each step in HR. We conclude by outlining future directions for elucidating the downstream mechanisms of RAD51-mediated HR in the chromatin context.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"154 ","pages":"Article 103891"},"PeriodicalIF":2.7,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145088633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01DOI: 10.1016/j.dnarep.2025.103862
Penny Jeggo, Bennett Van Houten
{"title":"Editors’ note Penny Jeggo and Bennett Van Houten","authors":"Penny Jeggo, Bennett Van Houten","doi":"10.1016/j.dnarep.2025.103862","DOIUrl":"10.1016/j.dnarep.2025.103862","url":null,"abstract":"","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"153 ","pages":"Article 103862"},"PeriodicalIF":2.7,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144565567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01DOI: 10.1016/j.dnarep.2025.103878
Min-Guk Cho , Gaorav P. Gupta
{"title":"Corrigendum to “Unveiling cGAS mechanisms: Insights into DNA damage and immune sensing in cancer” [DNA Repair 152 (2025) 103868]","authors":"Min-Guk Cho , Gaorav P. Gupta","doi":"10.1016/j.dnarep.2025.103878","DOIUrl":"10.1016/j.dnarep.2025.103878","url":null,"abstract":"","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"153 ","pages":"Article 103878"},"PeriodicalIF":2.7,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144769462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01DOI: 10.1016/j.dnarep.2025.103888
Maria Berruezo-Llacuna , Eleni Kabrani , Michela Di Virgilio
The ability of B lymphocytes to diversify immunoglobulin (Ig) genes is central to the generation of high-affinity, class-switched antibodies and the establishment of effective humoral immunity. This diversification is achieved through three DNA remodeling processes that occur at defined stages of B cell development and maturation: V(D)J recombination, somatic hypermutation (SHM), and class switch recombination (CSR). These reactions all rely on the induction of programmed DNA lesions at Ig genes and their productive resolution by ubiquitous DNA repair pathways. However, such physiological sources of genotoxic stress render B cells vulnerable to genome instability, including mutations and chromosomal translocations that drive malignancies. Therefore, B cells have evolved complex regulatory networks that ensure efficient Ig gene diversification while minimizing the risk of unproductive or deleterious repair outcomes. In this review, we integrate foundational studies with recent mechanistic advances to outline how B cells exploit, coordinate, and constrain DNA repair to balance immune receptor diversification with the preservation of genome integrity.
{"title":"The B cell dilemma: Diversity or fidelity?","authors":"Maria Berruezo-Llacuna , Eleni Kabrani , Michela Di Virgilio","doi":"10.1016/j.dnarep.2025.103888","DOIUrl":"10.1016/j.dnarep.2025.103888","url":null,"abstract":"<div><div>The ability of B lymphocytes to diversify immunoglobulin (<em>Ig</em>) genes is central to the generation of high-affinity, class-switched antibodies and the establishment of effective humoral immunity. This diversification is achieved through three DNA remodeling processes that occur at defined stages of B cell development and maturation: V(D)J recombination, somatic hypermutation (SHM), and class switch recombination (CSR). These reactions all rely on the induction of programmed DNA lesions at <em>Ig</em> genes and their productive resolution by ubiquitous DNA repair pathways. However, such physiological sources of genotoxic stress render B cells vulnerable to genome instability, including mutations and chromosomal translocations that drive malignancies. Therefore, B cells have evolved complex regulatory networks that ensure efficient <em>Ig</em> gene diversification while minimizing the risk of unproductive or deleterious repair outcomes. In this review, we integrate foundational studies with recent mechanistic advances to outline how B cells exploit, coordinate, and constrain DNA repair to balance immune receptor diversification with the preservation of genome integrity.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"153 ","pages":"Article 103888"},"PeriodicalIF":2.7,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01DOI: 10.1016/j.dnarep.2025.103889
Gerarda van de Kamp , Israel Tojal da Silva , Sander Barnhoorn , Roland Kanaar , Jeroen Essers
DNA crosslink-inducing drugs are widely used in clinical settings for treatment of solid tumors. Double strand breaks (DSBs) that arise during interstrand crosslink (ICL) repair are crucial determinants of the therapeutic response, as they lead to cell death if not repaired. DSBs can be repaired through non-homologous end joining (NHEJ), theta-mediated end joining (TMEJ), and homologous recombination (HR). HR is considered a major pathway for repairing DSBs induced during ICL repair. In this study, we examine the roles of NHEJ, TMEJ, and HR in ICL repair using mouse embryonic stem (mES) cells. We show that DNA-PKcs-deficient mES cells are resistant to the crosslinkers mitomycin C (MMC), cisplatin and carboplatin, contrasting with the increased sensitivity observed in mES cells lacking Rad54. Furthermore, the absence of DNA-PKcs correlates with enhanced HR activity, as evidenced by an increased number of Rad54 foci following MMC treatment. The combined knock-outof DNA-PKcs and Rad54 reduces sensitivity to crosslinkers compared to cells lacking only Rad54, suggesting the involvement of another DSB repair pathway besides HR. We found that TMEJ deficiency can sensitize cells to cisplatin, particularly in those lacking NHEJ and HR repair. This suggests that TMEJ contributes to cell survival following cisplatin treatment. In clinical settings, higher PRKDC expression correlates with poorer survival, while elevated RAD54L and POLQ expression correlates with better survival in cisplatin-treated cervical and head and neck cancers. These findings reflect the opposing roles of NHEJ versus HR and TMEJ in replication-associated DSB repair, as observed in vitro.
{"title":"Contributions of DNA double strand break repair pathways to DNA crosslink repair","authors":"Gerarda van de Kamp , Israel Tojal da Silva , Sander Barnhoorn , Roland Kanaar , Jeroen Essers","doi":"10.1016/j.dnarep.2025.103889","DOIUrl":"10.1016/j.dnarep.2025.103889","url":null,"abstract":"<div><div>DNA crosslink-inducing drugs are widely used in clinical settings for treatment of solid tumors. Double strand breaks (DSBs) that arise during interstrand crosslink (ICL) repair are crucial determinants of the therapeutic response, as they lead to cell death if not repaired. DSBs can be repaired through non-homologous end joining (NHEJ), theta-mediated end joining (TMEJ), and homologous recombination (HR). HR is considered a major pathway for repairing DSBs induced during ICL repair. In this study, we examine the roles of NHEJ, TMEJ, and HR in ICL repair using mouse embryonic stem (mES) cells. We show that DNA-PK<sub>cs</sub>-deficient mES cells are resistant to the crosslinkers mitomycin C (MMC), cisplatin and carboplatin, contrasting with the increased sensitivity observed in mES cells lacking Rad54. Furthermore, the absence of DNA-PK<sub>cs</sub> correlates with enhanced HR activity, as evidenced by an increased number of Rad54 foci following MMC treatment. The combined knock-outof DNA-PK<sub>cs</sub> and Rad54 reduces sensitivity to crosslinkers compared to cells lacking only Rad54, suggesting the involvement of another DSB repair pathway besides HR. We found that TMEJ deficiency can sensitize cells to cisplatin, particularly in those lacking NHEJ and HR repair. This suggests that TMEJ contributes to cell survival following cisplatin treatment. In clinical settings, higher <em>PRKDC</em> expression correlates with poorer survival, while elevated <em>RAD54L</em> and <em>POLQ</em> expression correlates with better survival in cisplatin-treated cervical and head and neck cancers. These findings reflect the opposing roles of NHEJ versus HR and TMEJ in replication-associated DSB repair, as observed <em>in vitro</em>.</div></div>","PeriodicalId":300,"journal":{"name":"DNA Repair","volume":"153 ","pages":"Article 103889"},"PeriodicalIF":2.7,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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