Eukaryotic chromatin consisting of nucleosomes connected by linker DNA is organized into higher order structures,which is facilitated by linker histone H1.Formation of chromatin compacts and protects the genome,but al...Eukaryotic chromatin consisting of nucleosomes connected by linker DNA is organized into higher order structures,which is facilitated by linker histone H1.Formation of chromatin compacts and protects the genome,but also hinders DNA transactions.Cells have evolved mechanisms to modify/remodel chromatin resulting in chromatin states suitable for genome functions.The high mobility group box(HMGB)proteins are non-histone chromatin architectural factors characterized by one or more HMGB motifs that bind DNA in a sequence nonspecific fashion.They play a major role in chromatin dynamics.The Saccharomyces cerevisiae(yeast hereafter)HMGB protein Hmo1 contains two HMGB motifs.However,unlike a canonical HMGB protein that has an acidic C-terminus,Hmo1 ends with a lysine rich,basic,C-terminus,resembling linker histone H1.Hmo1 exhibits characteristics of both HMGB proteins and linker histones in its multiple functions.For instance,Hmo1 promotes transcription by RNA polymerases I and II like canonical HMGB proteins but makes chromatin more compact/stable like linker histones.Recent studies have demonstrated that Hmo1 destabilizes/disrupts nucleosome similarly as other HMGB proteins in vitro and acts to maintain a common topological architecture of genes in yeast genome.This minireview reviews the functions of Hmo1 and the underlying mechanisms,highlighting recent discoveries.展开更多
真核细胞的房间的染色体在由环境代理人和内长的新陈代谢的副产品的连续袭击下面。在 DNA 导致的损坏通常导致细胞的事件的串联， DNA 损坏反应。DNA 损坏反应的失败能由减少 DNA 修理的效率和忠实导致恶意的开发。NBS1 蛋白质是在对 D...真核细胞的房间的染色体在由环境代理人和内长的新陈代谢的副产品的连续袭击下面。在 DNA 导致的损坏通常导致细胞的事件的串联， DNA 损坏反应。DNA 损坏反应的失败能由减少 DNA 修理的效率和忠实导致恶意的开发。NBS1 蛋白质是在对 DNA 损坏和 chromosomal 正直的维护的细胞的反应起一个关键作用的 MRE11/RAD50/NBS1 建筑群(MRN ) 的一个部件。在 NBS1 基因的变化为 Nijmegen 破裂症候群(NBS ) 负责，给予增加的倾向到恶意的开发的世袭混乱。从病人们在 DNA 双海滨裂缝的修理指向缺乏的 NBS 孤立的房间的 phenotypic 特征。这里，我们在 DNA 损坏反应考察 NBS1 的角色的当前的知识。强调在 DNA 双海滨修理，察觉到并且发信号的 DNA 损坏的调整，房间周期检查点控制和 telomere 稳定性的维护被放在 NBS1 的角色上。展开更多
Objective:Mitotic arrest-deficient protein 1(MAD1)is a kinetochore protein essential for the mitotic spindle checkpoint.Proteomic studies have indicated that MAD1 is a component of the DNA damage response(DDR)pathway....Objective:Mitotic arrest-deficient protein 1(MAD1)is a kinetochore protein essential for the mitotic spindle checkpoint.Proteomic studies have indicated that MAD1 is a component of the DNA damage response(DDR)pathway.However,whether and how MAD1 might be directly involved in the DDR is largely unknown.Methods:We ectopically expressed the wild type,or a phosphorylation-site--mutated form of MAD1 in MAD1 knockdown cells to look for complementation effects.We used the comet assay,colony formation assay,immunofluorescence staining,and flow cytometry to assess the DDR,radiosensitivity,and the G2/M checkpoint.We employed co-immunoprecipitation followed by mass spectrometry to identify MAD1 interacting proteins.Data were analyzed using the unpaired Student'st-test.Results:We showed that MAD1 was required for an optimal DDR,as knocking down MAD1 resulted in impaired DNA repair and hypersensitivity to ionizing radiation(IR).We found that IR-induced serine 214 phosphorylation was ataxia-telangiectasia mutated(ATM)kinase-dependent.Mutation of serine 214 to alanine failed to rescue the phenotypes of MAD1 knockdown cells in response to IR.Using mass spectrometry,we identified a protein complex mediated by MAD1 serine 214 phosphorylation in response to IR.Among them,we showed that KU80 was a key protein that displayed enhanced interaction with MAD1 after DNA damage.Finally,we showed that MAD1 interaction with KU80 required serine 214 phosphorylation,and it was essential for activation of DNA protein kinases catalytic subunit(DNA-PKcs).Conclusions:MAD1 serine 214 phosphorylation mediated by ATM kinase in response to IR was required for the interaction with KU80 and activation of DNA-PKCs.展开更多
AIM: To investigate the expression deficiency of key molecular markers in the homologous recombination pathway. METHODS: Expression loss of breast cancer type 1 susceptibility protein (BRCA1), ataxia telangiectasia mu...AIM: To investigate the expression deficiency of key molecular markers in the homologous recombination pathway. METHODS: Expression loss of breast cancer type 1 susceptibility protein (BRCA1), ataxia telangiectasia mutated (ATM), ATM-Rad3-related (ATR), mediator of DNA damage checkpoint protein 1 (MDC1) and meiotic recombination 11 (Mre11) were correlated with their clinicopathological parameters in gastric cancer (GC). One hundred and twenty treatment-naive GC samples were formalin-fixed and paraffin-embedded into tissue blocks. Two representative cores from each block were extracted and constructed into tissue microarrays. Expression levels of BRCA1, ATM, ATR, MDC1 and Mre11 were determined using immunohistochemical analysis, and correlated with clinical parameters, including age, gender, Lauren subtype, tumor grades, clinical stage and overall survival.RESULTS: Expression loss of BRCA1, ATM, ATR, MDC1, and Mre11 was found in 21.4%, 20.2%, 21.0%, 11.1% and 4.6%, respectively, of interpretable cases. BRCA1 loss was significantly associated with patients of diffused subtype (intestinal vs diffused, 8.2% vs 31.7%, P = 0.001), higher tumor grade (Ⅰ/Ⅱ vs Ⅲ, 10.7% vs 20.5;Ⅰ/Ⅱ vs Ⅳ, 10.7% vs 54.5%, P = 0.047) and advanced clinical stage (Ⅰ/Ⅱ vs Ⅲ, 12.9% vs 16.9%;Ⅰ /Ⅱ vs Ⅳ, 12.9% vs 45.5%, P = 0.006). MDC1 loss was significantly associated with patients of diffused subtype (intestinal vs diffused, 0% vs 19.7%, P = 0.001) and higher tumor grade (Ⅰ/Ⅱ vs Ⅲ, 0% vs 12%;Ⅰ/Ⅱ vs Ⅳ, 0% vs 30.8%, P = 0.012). In addition, the survival time of the patients with expression loss of BRCA1 was significantly shorter than those with positive expression of BRCA1 (2-year survival rate, 32.4% vs 62.8%, P = 0.015). No correlations were found between clinicopathological parameters and expression loss of ATM, ATR and Mre11. CONCLUSION: Our results support the hypothesis that homologous recombination deficiency plays an important role in the progression of gastric carcinoma. Loss of expression of BRCA1 and MDC1 may serve as predictive factors in tumor development or progression in GC patients.展开更多
目的探讨miR-590-5p、DNA损伤检查点蛋白调节子1(mediator of DNA damage checkpoint 1,MDC1)在高级别胶质瘤(high-grade glioma,HGG)组织中的表达及与胶质瘤病人术后放疗效果的关系,并明确二者对胶质瘤细胞增殖、凋亡的影响。方法选取2...目的探讨miR-590-5p、DNA损伤检查点蛋白调节子1(mediator of DNA damage checkpoint 1,MDC1)在高级别胶质瘤(high-grade glioma,HGG)组织中的表达及与胶质瘤病人术后放疗效果的关系,并明确二者对胶质瘤细胞增殖、凋亡的影响。方法选取2019年1月至2021年2月河北北方学院附属第一医院64例HGG患者,评估放疗效果。实时荧光定量PCR(qRT-PCR)法检测miR-590-5p水平,免疫组织化学染色检测MDC1表达情况,分析miR-590-5p、MDC1表达与胶质瘤病人术后放疗效果的关系,多因素Logistic回归分析影响HGG患者术后放疗效果的因素;体外培养胶质瘤U87MG细胞,并分别转染miR-590-5p mimic、MDC1-shRNA及其阴性对照,CCK-8法和流式细胞术分别检测细胞增殖和凋亡;构建裸鼠移植瘤模型,观察过表达miR-590-5p和敲低MDC1对肿瘤生长的影响。结果MDC1在HGG组织中的表达较正常脑组织中升高,mi R-590-5p表达较正常脑组织降低,二者表达水平呈负相关;MDC1表达升高、miR-590-5p表达降低,其放疗效果越差;Logistic回归分析显示,MDC1高表达、miR-590-5p低表达均是影响HGG患者放疗效果的危险因素。过表达miR-590-5p和敲低MDC1后,U87MG细胞增殖力降低,凋亡率升高,移植瘤体积和重量下降,Ki-67阳性细胞比例减少。过表达miR-590-5p后MDC1蛋白表达明显下降。结论HGG组织中miR-590-5p呈低表达,MDC1呈高表达,二者表达与HGG的发生和患者术后放疗效果关系密切;过表达miR-590-5p和敲低MDC1表达可抑制胶质瘤细胞增殖并促进凋亡。展开更多
文摘Eukaryotic chromatin consisting of nucleosomes connected by linker DNA is organized into higher order structures,which is facilitated by linker histone H1.Formation of chromatin compacts and protects the genome,but also hinders DNA transactions.Cells have evolved mechanisms to modify/remodel chromatin resulting in chromatin states suitable for genome functions.The high mobility group box(HMGB)proteins are non-histone chromatin architectural factors characterized by one or more HMGB motifs that bind DNA in a sequence nonspecific fashion.They play a major role in chromatin dynamics.The Saccharomyces cerevisiae(yeast hereafter)HMGB protein Hmo1 contains two HMGB motifs.However,unlike a canonical HMGB protein that has an acidic C-terminus,Hmo1 ends with a lysine rich,basic,C-terminus,resembling linker histone H1.Hmo1 exhibits characteristics of both HMGB proteins and linker histones in its multiple functions.For instance,Hmo1 promotes transcription by RNA polymerases I and II like canonical HMGB proteins but makes chromatin more compact/stable like linker histones.Recent studies have demonstrated that Hmo1 destabilizes/disrupts nucleosome similarly as other HMGB proteins in vitro and acts to maintain a common topological architecture of genes in yeast genome.This minireview reviews the functions of Hmo1 and the underlying mechanisms,highlighting recent discoveries.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.81672743 and 81974464)Beijing Tianjin Hebei Basic Research Cooperation Project(Grant No.19JCZDJC64500(Z))+4 种基金Shenzhen Basic Research Project(Grant No.JCYJ20160331114230843)Tianjin Municipal Health Commission(Grant Nos.2015KR11 and 2013KG134)Tianjin Municipal Science and Technology Bureau(Grant No.18JCYBJC27800)US NIH grant RO 1 CAI33093,the Alabama Innovation Fund of the United Statesthe Tianjin Medical University Cancer Institute and Hospital Innovation Fund(Grant No.1803)。
文摘Objective:Mitotic arrest-deficient protein 1(MAD1)is a kinetochore protein essential for the mitotic spindle checkpoint.Proteomic studies have indicated that MAD1 is a component of the DNA damage response(DDR)pathway.However,whether and how MAD1 might be directly involved in the DDR is largely unknown.Methods:We ectopically expressed the wild type,or a phosphorylation-site--mutated form of MAD1 in MAD1 knockdown cells to look for complementation effects.We used the comet assay,colony formation assay,immunofluorescence staining,and flow cytometry to assess the DDR,radiosensitivity,and the G2/M checkpoint.We employed co-immunoprecipitation followed by mass spectrometry to identify MAD1 interacting proteins.Data were analyzed using the unpaired Student'st-test.Results:We showed that MAD1 was required for an optimal DDR,as knocking down MAD1 resulted in impaired DNA repair and hypersensitivity to ionizing radiation(IR).We found that IR-induced serine 214 phosphorylation was ataxia-telangiectasia mutated(ATM)kinase-dependent.Mutation of serine 214 to alanine failed to rescue the phenotypes of MAD1 knockdown cells in response to IR.Using mass spectrometry,we identified a protein complex mediated by MAD1 serine 214 phosphorylation in response to IR.Among them,we showed that KU80 was a key protein that displayed enhanced interaction with MAD1 after DNA damage.Finally,we showed that MAD1 interaction with KU80 required serine 214 phosphorylation,and it was essential for activation of DNA protein kinases catalytic subunit(DNA-PKcs).Conclusions:MAD1 serine 214 phosphorylation mediated by ATM kinase in response to IR was required for the interaction with KU80 and activation of DNA-PKCs.
文摘AIM: To investigate the expression deficiency of key molecular markers in the homologous recombination pathway. METHODS: Expression loss of breast cancer type 1 susceptibility protein (BRCA1), ataxia telangiectasia mutated (ATM), ATM-Rad3-related (ATR), mediator of DNA damage checkpoint protein 1 (MDC1) and meiotic recombination 11 (Mre11) were correlated with their clinicopathological parameters in gastric cancer (GC). One hundred and twenty treatment-naive GC samples were formalin-fixed and paraffin-embedded into tissue blocks. Two representative cores from each block were extracted and constructed into tissue microarrays. Expression levels of BRCA1, ATM, ATR, MDC1 and Mre11 were determined using immunohistochemical analysis, and correlated with clinical parameters, including age, gender, Lauren subtype, tumor grades, clinical stage and overall survival.RESULTS: Expression loss of BRCA1, ATM, ATR, MDC1, and Mre11 was found in 21.4%, 20.2%, 21.0%, 11.1% and 4.6%, respectively, of interpretable cases. BRCA1 loss was significantly associated with patients of diffused subtype (intestinal vs diffused, 8.2% vs 31.7%, P = 0.001), higher tumor grade (Ⅰ/Ⅱ vs Ⅲ, 10.7% vs 20.5;Ⅰ/Ⅱ vs Ⅳ, 10.7% vs 54.5%, P = 0.047) and advanced clinical stage (Ⅰ/Ⅱ vs Ⅲ, 12.9% vs 16.9%;Ⅰ /Ⅱ vs Ⅳ, 12.9% vs 45.5%, P = 0.006). MDC1 loss was significantly associated with patients of diffused subtype (intestinal vs diffused, 0% vs 19.7%, P = 0.001) and higher tumor grade (Ⅰ/Ⅱ vs Ⅲ, 0% vs 12%;Ⅰ/Ⅱ vs Ⅳ, 0% vs 30.8%, P = 0.012). In addition, the survival time of the patients with expression loss of BRCA1 was significantly shorter than those with positive expression of BRCA1 (2-year survival rate, 32.4% vs 62.8%, P = 0.015). No correlations were found between clinicopathological parameters and expression loss of ATM, ATR and Mre11. CONCLUSION: Our results support the hypothesis that homologous recombination deficiency plays an important role in the progression of gastric carcinoma. Loss of expression of BRCA1 and MDC1 may serve as predictive factors in tumor development or progression in GC patients.
文摘目的探讨miR-590-5p、DNA损伤检查点蛋白调节子1(mediator of DNA damage checkpoint 1,MDC1)在高级别胶质瘤(high-grade glioma,HGG)组织中的表达及与胶质瘤病人术后放疗效果的关系,并明确二者对胶质瘤细胞增殖、凋亡的影响。方法选取2019年1月至2021年2月河北北方学院附属第一医院64例HGG患者,评估放疗效果。实时荧光定量PCR(qRT-PCR)法检测miR-590-5p水平,免疫组织化学染色检测MDC1表达情况,分析miR-590-5p、MDC1表达与胶质瘤病人术后放疗效果的关系,多因素Logistic回归分析影响HGG患者术后放疗效果的因素;体外培养胶质瘤U87MG细胞,并分别转染miR-590-5p mimic、MDC1-shRNA及其阴性对照,CCK-8法和流式细胞术分别检测细胞增殖和凋亡;构建裸鼠移植瘤模型,观察过表达miR-590-5p和敲低MDC1对肿瘤生长的影响。结果MDC1在HGG组织中的表达较正常脑组织中升高,mi R-590-5p表达较正常脑组织降低,二者表达水平呈负相关;MDC1表达升高、miR-590-5p表达降低,其放疗效果越差;Logistic回归分析显示,MDC1高表达、miR-590-5p低表达均是影响HGG患者放疗效果的危险因素。过表达miR-590-5p和敲低MDC1后,U87MG细胞增殖力降低,凋亡率升高,移植瘤体积和重量下降,Ki-67阳性细胞比例减少。过表达miR-590-5p后MDC1蛋白表达明显下降。结论HGG组织中miR-590-5p呈低表达,MDC1呈高表达,二者表达与HGG的发生和患者术后放疗效果关系密切;过表达miR-590-5p和敲低MDC1表达可抑制胶质瘤细胞增殖并促进凋亡。
