Maternal gene Ooep may participate in homologous recombination-mediated DNA double-strand break repair in mouse oocytes

DNA damage in oocytes can cause infertility and birth defects. DNA double-strand breaks （DSBs） are highly deleterious and can substantially impair genome integrity. Homologous recombination （HR）-mediated DNA DSB repair plays dominant roles in safeguarding oocyte quantity and quality. However, little is known regarding the key players of the HR repair pathway in oocytes. Here, we identified oocyte-specific gene Ooep as a novel key component of the HR repair pathway in mouse oocytes. OOEP was required for efficient ataxia telangiectasia mutated （ATM） kinase activation and Rad51 recombinase （RAD51） focal accumulation at DNA DSBs. Ooep null oocytes were defective in DNA DSB repair and prone to apoptosis upon exogenous DNA damage insults. Moreover, Ooep null oocytes exhibited delayed meiotic maturation. Therefore, OOEP played roles in preserving oocyte quantity and quality by maintaining genome stability. Ooep expression decreased with the advance of maternal age, suggesting its involvement in maternal aging.

Homologous recombination in DNA repair and DNA damage tolerance

Homologous recombination （HR） comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks （DSBs） and interstrand crosslinks （ICLs）. In addition, recombination provides critical support for DNA replication in the recovery of stalled or broken replication forks, contributing to tolerance of DNA damage. A central core of proteins, most critically the RecA homolog Rad51, catalyzes the key reactions that typify HR： homology search and DNA strand invasion. The diverse functions of recombination are reflected in the need for context-specific factors that perform supplemental functions in conjunction with the core proteins. The inability to properly repair complex DNA damage and resolve DNA replication stress leads to genomic instability and contributes to cancer etiology. Mutations in the BRCA2 recombination gene cause predisposition to breast and ovarian cancer as well as Fanconi anemia, a cancer predisposition syndrome characterized by a defect in the repair of DNA interstrand crosslinks. The cellular functions of recombination are also germane to DNA-based treatment modalities of cancer, which target replicating cells by the direct or indirect induction of DNA lesions that are substrates for recombination pathways. This review focuses on mechanistic aspects of HR relating to DSB and ICL repair as well as replication fork support.

Low testing rates and high BRCA prevalence: Poly (ADP-ribose) polymerase inhibitor use in Middle East BRCA/homologous recombination deficiency-positive cancer patients

BACKGROUND Poly(ADP-ribose)polymerase inhibitors(PARPis)are approved as first-line therapies for breast cancer gene(BRCA)-positive,human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer.They are also effective for new and recurrent ovarian cancers that are BRCA-or homologous recombination deficiency(HRD)-positive.However,data on these mutations and PARPi use in the Middle East are limited.AIM To assess BRCA/HRD prevalence and PARPi use in patients in the Middle East with breast/ovarian cancer.METHODS This was a single-center retrospective study of 57 of 472 breast cancer patients tested for BRCA mutations,and 25 of 65 ovarian cancer patients tested for HRD.These adult patients participated in at least four visits to the oncology service at our center between August 2021 and May 2023.Data were summarized using descriptive statistics and compared using counts and percentages.Response to treatment was assessed using Response Evaluation Criteria in Solid Tumors criteria.RESULTS Among the 472 breast cancer patients,12.1%underwent BRCA testing,and 38.5%of 65 ovarian cancer patients received HRD testing.Pathogenic mutations were found in 25.6%of the tested patients:26.3%breast cancers had germline BRCA(gBRCA)mutations and 24.0%ovarian cancers showed HRD.Notably,40.0%of gBRCA-positive breast cancers and 66.0%of HRD-positive ovarian cancers were Middle Eastern and Asian patients,respectively.PARPi treatment was used in 5(33.3%)gBRCA-positive breast cancer patients as first-line therapy(n=1;7-months progression-free),for maintenance(n=2;>15-months progression-free),or at later stages due to compliance issues(n=2).Four patients(66.6%)with HRD-positive ovarian cancer received PARPi and all remained progression-free.CONCLUSION Lower testing rates but higher BRCA mutations in breast cancer were found.Ethnicity reflected United Arab Emirates demographics,with breast cancer in Middle Eastern and ovarian cancer in Asian patients.

DNA同源重组修复与乳腺癌的研究进展

双链断裂是真核细胞最严重的DNA损伤类型,主要依赖同源重组途径进行修复。BRCA1/2是该修复通路中的关键因子,以其为核心组成的BRCA肿瘤抑制因子网络中多种致病性突变均可损伤基因组完整性和稳定性,增高乳腺癌易感性。该文结合最新研究进展,对DNA同源重组修复网络中关键基因突变与乳腺癌易感性及个体化治疗策略进行综述,旨在促进相关突变携带者的乳腺癌早期预防、分子诊断和精准治疗。

DNA双链断裂修复基因遗传多态性与非小细胞肺癌预后的相关性

目的探讨DNA双链断裂修复(DSBR)基因遗传多态性与非小细胞肺癌(NSCLC)预后的关联。方法应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)和TaqMan探针技术检测679例NSCLC新发病例的DSBR 10个SNP(rs6869366、rs1056503、rs3734091、rs861539、rs861537、rs1799794、rs16942、rs144848、rs1805794、rs2735383)的基因分型,应用Kaplan-Meier、Log rank检验和Cox回归模型进行预后分析。结果患者总体5年生存率为29.8%(95%CI:26.1%~33.5%)。化疗患者携带XRCC3 rs861539 CT+TT基因型的死亡风险低于携带CC基因型患者(MST:32月vs.60月HR=0.629,95%CI:0.411~0.962,P=0.032;aHR=0.623,95%CI:0.399~0.973,P=0.038);鳞癌患者携带BRCA1 rs16942 AG+GG等位基因型比携带AA基因型的预后差(MST:24月vs.31月;aHR=1.622,95%CI:1.139~2.310,P=0.007);非吸烟女性腺癌患者携带NBS1 rs2735383GC+CC基因型较携带GG基因型的死亡风险低(MST:41月vs.32月;aHR=0.420,95%CI:0.247~0.714,P=0.0 0 1);携带X R C C 3r s 8 6 1 5 3 9 C T+T T基因型的临床早期病例较携带CC基因型的死亡风险降低(aHR=0.444,95%CI:0.192~1.025,P=0.057);男性吸烟的早期患者携带NBS1 rs1805794CG+GG基因型比CC基因型的死亡风险高(aHR=2.768,95%CI:1.273~6.017,P=0.010);携带XRCC3 rs861537 AA基因型的临床晚期病例较携带GG基因型的死亡风险增加(aHR=1.750,95%CI:1.021~3.001,P=0.042)。联合分析发现,患者携带4个或5个不利基因型比携带≤3个不利基因型的死亡风险增加(aHR=1.153,95%CI:1.005~1.322,Ptrend=0.042)。结论DSBR基因遗传多态性可作为NSCLC患者预后评价的参考。

Role of deubiquitinating enzymes in DNA double-strand break repair

DNA is the hereditary material in humans and almost all other organisms. It is essential for maintaining accurate transmission of genetic information. In the life cycle, DNA replication, cell division, or genome damage, including that caused by endogenous and exogenous agents, may cause DNA aberrations. Of all forms of DNA damage, DNA double-strand breaks(DSBs) are the most serious. If the repair function is defective, DNA damage may cause gene mutation, genome instability, and cell chromosome loss, which in turn can even lead to tumorigenesis. DNA damage can be repaired through multiple mechanisms. Homologous recombination(HR) and non-homologous end joining(NHEJ) are the two main repair mechanisms for DNA DSBs. Increasing amounts of evidence reveal that protein modifications play an essential role in DNA damage repair.Protein deubiquitination is a vital post-translational modification which removes ubiquitin molecules or polyubiquitinated chains from substrates in order to reverse the ubiquitination reaction. This review discusses the role of deubiquitinating enzymes(DUBs) in repairing DNA DSBs. Exploring the molecular mechanisms of DUB regulation in DSB repair will provide new insights to combat human diseases and develop novel therapeutic approaches.

p53 and its isoforms in DNA double-stranded break repair

DNA double-stranded break(DSB)is one of the most catastrophic damages of genotoxic insult.Inappropriate repair of DNA DSBs results in the loss of genetic information,mutation,and the generation of harmful genomic rearrangements,which predisposes an organism to immunodeficiency,neurological damage,and cancer.The tumor repressor p53 plays a key role in DNA damage response,and has been found to be mutated in 50%of human cancer.p53,p63,and p73 are three members of the p53 gene family.Recent discoveries have shown that human p53 gene encodes at least 12 isoforms.Different p53 members and isoforms play various roles in orchestrating DNA damage response to maintain genomic integrity.This review briefly explores the functions of p53 and its isoforms in DNA DSB repair.

The DNA damage and regulatory strategy in hematopoietic stem cells after irradiation exposure:Progress and challenges

The hematopoietic system is susceptible to ionizing radiation(IR),which can cause acute hematopoietic failure or long-term myelosuppression.As the most primitive cells of the hematopoietic hierarchy,hematopoietic stem cells(HSCs)maintain lifelong hematopoietic homeostasis and promote hematopoietic regeneration during stress.Numerous studies have shown that nuclear and mitochondrial genomes are the main targets of radiation injury in HSCs.More importantly,the damage of DNA may trigger a series of biological responses that largely determine HSC fate following IR exposure.Although some essential pathways and factors involved in DNA injury and damage in HSCs have been revealed,a comprehensive understanding of the biological effects of radiation on HSCs still needs to be improved.This review focuses on recent insights into the molecular mechanisms underlying DNA damage and repair in HSCs after IR.Then summarize corresponding regulatory measures,which may provide a reference for further research in this field.

沉默PeroxiredoxinⅠ基因对乳腺癌裸鼠移植瘤放射敏感性的影响

目的探讨PeroxiredoxinⅠ(PrxⅠ)沉默后对乳腺癌裸鼠移植瘤放射敏感性的影响及其作用机制。方法将稳定表达PrxⅠshRNA的pGPU6-PrxⅠ和阴性对照pGPU6-HK细胞接种于裸鼠皮下,建立乳腺癌裸鼠移植瘤模型。实验共分为4组:pGPU6-HK组、pGPU6-PrxⅠ组、pGPU6-HK+照射(ionizing radiation,IR)组、pGPU6-PrxⅠ+IR组。用6MVX线照射裸鼠瘤组织,测量肿瘤体积,称取肿瘤质量,计算抑瘤率;免疫组化检测肿瘤组织中PrxⅠ和Caspase3蛋白表达;电镜观察肿瘤细胞超微结构,Western blot测定肿瘤组织中γ-H2AX和Rad51蛋白表达。结果成功构建了裸鼠移植瘤模型,pGPU6-PrxⅠ+IR组裸鼠移植瘤生长肿瘤明显迟缓,体积较小,抑瘤率为79.76%,与pGPU6-PrxⅠ(34.92%)和pGPU6-HK+IR(56.94%)比较差异具有显著性(P<0.05);给予pGPU6-PrxⅠ及IR处理后,肿瘤细胞凋亡和坏死增多,PrxⅠ和Rad51蛋白表达减少,而Caspase3和γ-H2AX蛋白表达增加,以pGPU6-PrxⅠ+IR组更为显著,其Rad51蛋白下降了84.8%,γ-H2AX蛋白表达升高5.6倍(P<0.05)。结论沉默PrxⅠ表达可提高乳腺癌移植瘤的放射敏感性,其作用机制与DNA双链断裂增加、DNA损伤后修复能力降低有关。PrxⅠ可能是一个理想的乳腺癌放射增敏分子靶点。

DSB修复基因hKu70反义RNA真核表达载体构建

目的 构建人DNA双链断裂 (DSB)修复基因hKu70反义RNA真核表达载体pEGFP C1 K ,为以后的hKu70基因功能和毒理学研究提供实验材料。方法 提取人胚肺成纤维细胞 (HLF)总RNA ,逆转录酶 多聚酶链式反应 (RT PCR)扩增hKu70基因cDNA保守序列 ,经与pGEM T载体连接、筛选、克隆、抽提质粒和双酶切后 ,将纯化的hKu70基因cDNA保守序列反向插入绿色荧光蛋白表达载体pEGFP C1中 ,筛选、克隆、抽提质粒 ,从而构建hKu70基因反义RNA真核表达载体pEGFP C1 K。结果 经RT PCR获得 467bp含限制性内切酶位点的DNA片段 ,T载体克隆后经双酶切、测序 ,确定该片段为hKu70基因cDNA ,进而构建反义RNA真核表达载体pEGFP C1 K ,并双酶切 ,测序确证。结论 成功构建hKu70基因反义RNA真核表达载体pEGFP C1 K ,为建立该基因低表达细胞株。

CAS9 is a genome mutator by directly disrupting DNA-PK dependent DNA repair pathway

With its high efficiency for site-specific genome editing and easy manipulation,the clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR associated protein 9(CAS9)system has become the most widely used gene editing technology in biomedical research.In addition,significant progress has been made for the clinical development of CRISPR/CAS9 based gene therapies of human diseases,several of which are entering clinical trials.Here we report that CAS9 protein can function as a genome mutator independent of any exogenous guide RNA(gRNA)in human cells,promoting genomic DNA double-stranded break(DSB)damage and genomic instability.CAS9 interacts with the KU86 subunit of the DNA-dependent protein kinase(DNA-PK)complex and disrupts the interaction between KU86 and its kinase subunit,leading to defective DNA-PK-dependent repair of DNA DSB damage via non-homologous end-joining(NHEJ)pathway.XCAS9 is a CAS9 variant with potentially higher fidelity and broader compatibility,and dCAS9 is a CAS9 variant without nuclease activity.We show that XCAS9 and dCAS9 also interact with KU86 and disrupt DNA DSB repair.Considering the critical roles of DNA-PK in maintaining genomic stability and the pleiotropic impact of DNA DSB damage responses on cellular proliferation and survival,our findings caution the interpretation of data involving CRISPR/CAS9-based gene editing and raise serious safety concerns of CRISPR/CAS9 system in clinical application.

Ⅲ型家族性噬血细胞性淋巴组织细胞增生症易感基因UNC13D参与同源重组修复

本研究从DNA双链断裂同源重组修复角度探讨UNC13D(秀丽新小杆线虫)基因参与Ⅲ型家族性噬血细胞性淋巴组织细胞增生症(familial hemophagocytic lymphohistiocytosis type 3,FHL3)的发病机制。利用DNA同源重组修复方法,检测正常对照组及UNC13D基因下调后DR-U2OS细胞同源重组修复率的变化情况,并研究此基因的相关功能。结果表明:下调DR-U2OS细胞的UNC13D基因表达后,同源重组修复率较正常对照组明显下降,且差异有统计学意义(P<0.05),提示UNC13D编码蛋白Munc13-4不仅参与到细胞毒颗粒的胞吐过程中,而且在DNA双链断裂修复中也起作用。结论:UNC13D基因突变可能通过抑制细胞毒颗粒的胞吐和降低DNA双链断裂后的同源重组修复率参与FHL3发病过程,这一研究结果为揭示FHL3的发病机制提供新的理论基础。

基于同源重组的CRISPR精准基因编辑技术及其在农作物育种中的应用

随着CRISPR基因编辑技术的出现,几乎在任何动植物细胞基因组的特定目标位点,DNA大片段的“无缝”插入或替换,均可在CRISPR核酸酶产生双链切口后,在供体DNA存在的情况下,诱导同源定向修复来实现。目前,这种基于同源重组的CRISPR精准基因编辑在农作物基因功能分析和新技术育种中正发挥着越来越重要的作用。围绕在植物细胞中高效实现同源重组介导的CRISPR精准编辑这一目标,简述CRISPR精准编辑依赖的两种主要的基于同源重组的细胞修复机制,即合成依赖的链退火修复机制和非同源末端连接辅助的单链退火修复机制;在此基础上,详述产生DNA双链切口并诱导同源重组定向修复的CRISPR核酸酶和供体DNA/RNA,主要包括Cas9/12及其融合蛋白、sgRNA/crRNA及其修饰物、供体DNA/RNA及其修饰物;进而总结在植物遗传转化中为保障DNA双链切口和供体DNA/RNA发生的时空一致性以提高同源重组效率,而通常采用的CRISPR组分及供体DNA/RNA细胞递送方式;最后从功能基因组学研究和农作物新技术育种等方面,展望基于同源重组的CRISPR精准基因编辑技术的应用前景。

Exploiting DNA repair pathways for tumor sensitization,mitigation of resistance,and normal tissue protection in radiotherapy

More than half of cancer patients are treated with radiotherapy,which kills tumor cells by directly and indirectly inducing DNA damage,including cytotoxic DNA double-strand breaks(DSBs).Tumor cells respond to these threats by activating a complex signaling network termed the DNA damage response(DDR).The DDR arrests the cell cycle,upregulates DNA repair,and triggers apoptosis when damage is excessive.The DDR signaling and DNA repair pathways are fertile terrain for therapeutic intervention.This review highlights strategies to improve therapeutic gain by targeting DDR and DNA repair pathways to radiosensitize tumor cells,overcome intrinsic and acquired tumor radioresistance,and protect normal tissue.Many biological and environmental factors determine tumor and normal cell responses to ionizing radiation and genotoxic chemotherapeutics.These include cell type and cell cycle phase distribution;tissue/tumor microenvironment and oxygen levels;DNA damage load and quality;DNA repair capacity;and susceptibility to apoptosis or other active or passive cell death pathways.We provide an overview of radiobiological parameters associated with X-ray,proton,and carbon ion radiotherapy;DNA repair and DNA damage signaling pathways;and other factors that regulate tumor and normal cell responses to radiation.We then focus on recent studies exploiting DSB repair pathways to enhance radiotherapy therapeutic gain.

Profiling of the assembly of RecA nucleofilaments implies a potential target for environmental factors to disturb DNA repair

Double-strand breaks(DSBs),one class of the most harmful DNA damage forms that bring elevated health risks,need to be repaired timely and effectively.However,an increasing number of environmental pollutants have been identified to impair DSB repair from various mechanisms.Our previous work indicated that the formation of unsaturated Rec A nucleofilaments plays an essential role in homology recombination(HR) pathway which can accurately repair DSBs.In this study,by developing a benzonase cutting protection assay and combining it with traditional electrophoretic mobility shift assay(EMSA) analysis,we further investigated the assembly patterns of four Rec A mutants that display differential DSB repair ability and ATPase activity.We observed that the mutants(G204S and S69G) possessing both ATP hydrolysis and DSB repair activities form unsaturated nucleofilaments similar to that formed by the wild type Rec A,whereas the other two ATP hydrolysis-deficient mutants(K72R and E96D) that fail to mediate HR form more compacted nucleofilaments in the presence of ATP.These results establish a coupling of ATPase activity and effective DSB repair ability via the assembly status of Rec A nucleofilaments.This linkage provides a potential target for environmental factors to disturb the essential HR pathway for DSB repair by suppressing the ATPase activity and altering the assembly pattern of nucleofilaments.

DNA双链断裂修复基因NBS1多态性与肺癌易感性的关联研究

目的探讨DNA双链断裂修复基因NBSI多态性与肺癌遗传易感性的关系。方法采用病例对照设计，应用PCR—RFLP技术检测575例患者和575名对照的NBS1基因多态。结果对照组和病例组NBSlrsl805794的C／C、C／G、G／G基因型频率分别为25．9％、51．8％、22．3％和20．5％、52．3％、27．1％，两组分布差异有统计学意义（χ^2=6．38，P=0．04），携带C／G＋G／G基因型个体患肺癌的风险是携带C／C基因型者的1．46倍（OR=1．46，95％CI：1．09～1．97）。对照组和病例组NBSlrs2735383的G／G、G／C、C／C基因型频率分别为37．9％、47．0％、15．1％和35．5％、48．5％、16．0％，两组分布差异无统计学意义（χ^2=0．75，P=0．69）。携带Hap4-GC单体型或Hap4／Hap2单体型对者患肺癌的风险增加，OR值分别为1．70（95％CI：1．24～2．31）和1．75（95％CI：1．11～2．76），NBSl基因多态与吸烟有联合作用（P〈0．05）。结论NBSlrsl805794G／G基因型可能是肺癌的易感基因型，rsl805794和rs2735383位点构建的Hap4-GC单体型及Hap4／Hap2单体型对可能是肺癌的易感单体型和单体型对。

植物DNA断裂修复基因对农杆菌T-DNA整合的作用

转基因植物在作物新品种培育和生物制药中已发挥了巨大作用。农杆菌介导的遗传转化是广泛用于基因组分析的强大工具,也是获得转基因植物的主导技术。农杆菌介导的基因转移是极其复杂的生物学过程,需要许多农杆菌和植物的遗传因子协同参与完成。经过20多年的研究,人们对T-DNA产生和转运的分子机制以及农杆菌与寄主植物的互作已有所了解。T-DNA整合是农杆菌介导转化过程中最为关键的一步,但对于其整合机制所知仍有限。越来越多的证据表明,寄主植物细胞的DNA断裂修复基因对农杆菌T-DNA整合具有重要作用。该文首先介绍T-DNA转移的大致过程,重点讨论DNA断裂损伤修复相关基因对T-DNA整合的作用,为通过DNA损伤修复基因的遗传操纵来提高农杆菌介导植物遗传转化的效率提供参考。

DNA双链断裂修复基因XRCC5、LIG4的多态性与脑胶质瘤的相关性分析

目的探讨DNA双链断裂修复基因XRCC5、LIG4的多态性与脑胶质瘤的相关性。方法以126例脑胶质瘤患者以及120例健康志愿者作为研究对象,检测XRCC5基因rs828704、rs9288516位点以及LIG4基因rs3093737、rs3093739、rs10131位点的多态性,分析其与脑胶质瘤易感性的关系。结果XRCC5基因rs828704、rs9288516位点及LIG4基因rs3093737、rs3093739、rs10131位点在两组的分布均满足Hardy-Weinberg平衡(P>0.05)。病例组XRCC5基因rs9288516位点的A等位基因、LIG4基因rs10131位点的T等位基因频率高于对照组(P<0.05)。XRCC5基因rs9288516位点、LIG4基因rs10131位点在显性模型及加性模型下与胶质瘤易感性具有相关性(P<0.05);LIG4基因rs3093739位点在显性模型下与胶质瘤的易感性相关(P<0.05)。结论XRCC5基因rs9288516位点、LIG4基因rs10131位点与胶质瘤的易感性存在相关性。

DNA双链断裂修复基因3′UTR的多态性与汉族人年龄相关性白内障的关系

目的探讨DNA双链断裂修复基因3′非翻译区(3′UTR)的单核苷酸多态性(SNP)与汉族人年龄相关性白内障(ARC)的关系。方法提取无锡滨湖区和盐城阜宁县ARC患者(ARC组,789例)及正常人(对照组,789例)的全血基因组DNA;采用Taqman荧光探针和实时荧光定量PCR法分析4个双链断裂修复基因3′UTR的4个SNP位点的基因型,比较各位点在两组之间的分布差异并计算相对危险度(OR)。结果 XRCC5-rs1051685与ARC、皮质性和混合性ARC密切相关(OR=1.61、2.12和1.89,P<0.01),RAD52-rs1051669与ARC、皮质性和核性ARC密切相关(OR=0.72、0.69和0.71,P<0.05)。结论 XRCC5、RAD52基因3′UTR的多态性在汉族人ARC的发生、发展中起重要作用,不同亚型的ARC可能具有特异性的危险因素和致病机制。

Rad51基因沉默对铅诱导TK6细胞DNA双链断裂损伤修复的影响

目的研究Rad51基因沉默后对醋酸铅染毒致人淋巴母细胞(TK6细胞)DNA双链断裂损伤的修复作用的影响。方法构建Rad51沉默慢病毒载体及阴性对照,感染对数期TK6细胞,荧光定量PCR和Western blot验证感染效果。运用480μmol/L的醋酸铅染毒TK6细胞24 h(Control组、shRNA-NC组和shRNA-Rad51组),采用免疫荧光法检测TK6细胞的磷酸化组蛋白H2AX(γ-H2AX)的表达,Western Blot检测TK6细胞的Rad51、BRCA1、53BP1蛋白的表达。结果 shRNA-Rad51组的Rad51 mRNA表达水平和Rad51蛋白表达水平均低于Control组及shRNA-NC组(P <0.01);shRNA-Rad51组的γ-H2AX阳性率为(27.48±1.66)%,与Control组的(14.77±1.21)%及shRNA-NC组的(14.04±1.31)%比较,差异均有统计学意义(P <0.01);shRNA-Rad51组的BRCA1蛋白表达水平为(0.25±0.03),与Control组的(0.55±0.04)及shRNA-NC组的(0.51±0.04)比较,差异均有统计学意义(P <0.01);shRNARad51组的53BP1蛋白表达水平为(3.24±0.27),与Control组的(2.01±0.19)及shRNA-NC组的(2.11±0.17)比较,差异均有统计学意义(P <0.01)。结论 Rad51基因沉默后,TK6细胞HR修复通路受抑制和NHEJ修复通路激活,TK6细胞对铅遗传毒性的敏感性增强。