The eukaryotic genome is folded into higher-order conformation accompanied with constrained dynamics for coordinated genome functions.However,the molecular machinery underlying these hierarchically organized three-dim...The eukaryotic genome is folded into higher-order conformation accompanied with constrained dynamics for coordinated genome functions.However,the molecular machinery underlying these hierarchically organized three-dimensional(3D)chromatin architecture and dynamics remains poorly understood.Here by combining imaging and sequencing,we studied the role of lamin B1 in chromatin architecture and dynamics.We found that lamin B1 depletion leads to detachment of lamina-associated domains(LADs)from the nuclear periphery accompanied with global chromatin redistribution and decompaction.Consequently,the interchromosomal as well as inter-compartment interactions are increased,but the structure of topologically associating domains(TADs)is not affected.Using live-cell genomic loci tracking,we further proved that depletion of lamin B1 leads to increased chromatin dynamics,owing to chromatin decompaction and redistribution toward nucleoplasm.Taken together,our data suggest that lamin B1 and chromatin interactions at the nuclear periphery promote LAD maintenance,chromatin compaction,genomic compartmentalization into chromosome territories and A/B compartments and confine chromatin dynamics,supporting their crucial roles in chromatin higher-order structure and chromatin dynamics.展开更多
目的探讨核纤层蛋白B1(lamin B1,LMNB1)对肝癌进展的影响,发掘肝癌新的治疗靶点。方法利用工具网站基因表达水平值的交互式分析平台(Gene Expression Profiling Interactive Analysis,GEPIA)分析癌症基因组图谱数据库(The Cancer Genome...目的探讨核纤层蛋白B1(lamin B1,LMNB1)对肝癌进展的影响,发掘肝癌新的治疗靶点。方法利用工具网站基因表达水平值的交互式分析平台(Gene Expression Profiling Interactive Analysis,GEPIA)分析癌症基因组图谱数据库(The Cancer Genome Atlas,TCGA)中肝癌组织及癌旁组织LMNB1的表达水平,使用Kaplan-Meier分析LMNB1表达水平差异对肝癌患者预后的影响。采用实时定量聚合酶链式反应(polymerase chain reaction,PCR)检测正常肝细胞系及肝癌细胞系中LMNB1表达水平。选取LMNB1表达水平较高的两种人肝癌细胞株Hep3B、HepG2,转染小干扰RNA敲低LMNB1表达,在LMNB1表达水平较低的细胞SUN475中构建LMNB1稳定过表达细胞系并使用Western blot验证转染效率,采用CCK8法检测敲低或过表达LMNB1后肝癌细胞的增殖能力,采用平板克隆形成检测敲低或过表达LMNB1后细胞形成克隆的能力。采用Transwell检测敲低或过表达LMNB1后细胞侵袭及迁移能力的变化。采用Western blot实验检测磷酸化蛋白激酶B(phosphorylated protein kinase B,p-AKT)、蛋白激酶B(protein kinase B,AKT)、磷酸化细胞外调节蛋白激酶(phosphorylated extracellular regulated protein kinases,p-ERK)及细胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)的变化。结果TCGA数据库分析表明肝癌组织中LMNB1表达水平较癌旁正常组织高(P<0.05),且LMNB1表达水平与肝癌患者预后呈负相关(P=0.003)。实时定量PCR显示相对正常人肝细胞系,肝癌细胞中LMNB1 mRNA表达量分别为MHCC97H:1.80±0.10(t=11.08,P<0.001);SUN475:1.29±0.03(t=5.88,P=0.004);HepG2:2.97±0.04(t=39.68,P<0.001);PLC/Prf/5:1.74±0.04(t=14.51,P<0.001);HuH7:1.70±0.02(t=15.22,P<0.001);SK-HEP-1:1.59±0.05(t=11.17,P<0.001);Hep3B:2.27±0.09(t=18.50,P<0.001);均显著高于正常人肝细胞系。Westernblot结果显示在HepG2及Hep3B细胞系中,与siScramble阴性对照组相比,转染siLMNB1实验组的LMNB1表达水平显著降低(HepG2:0.60±0.10 vs 1.60±0.10,t=11.55,P<0.001;Hep3B:0.40±0.10 vs 1.70±0.10;t=15.61,P<0.001);而SUN475中转染质粒后LMNB1表达显著增加(0.70±0.20 vs 0.07±0.04;t=5.541,P=0.005)。敲低LMNB1后培养96 h,与对照组相比,Hep3B(10.81±0.67 vs 15.48±0.62;t=8.86,P<0.001)及HepG2(9.45±0.61 vs17.08±0.75;t=13.67,P<0.001)细胞增殖能力被显著抑制;而在SUN475中过表达LMNB1后,实验组细胞增殖活性显著增加(16.94±1.52 vs 12.65±1.06;t=3.99,P=0.016)。在HepG2及Hep3B细胞系中敲低LMNB1后,细胞克隆形成数显著减少[HepG2:(90.30±7.24)个vs(382.01±25.27)个,t=19.24,P<0.001;Hep3B:(128.03±8.24)个vs(395.85±28.27)个,t=15.76,P<0.001],在SUN475中过表达LMNB1组比对照组克隆形成个数显著增加[(467.82±42.45)个vs(85.31±15.32)个;t=14.87,P=0.001]。在HepG2及Hep3B细胞系中敲低LMNB1后,肝癌细胞迁移数量显著减少[HepG2:(75.25±8.10)个vs(15.02±3.50)个,t=11.90,P<0.001;Hep3B:(168.20±12.26)个vs(34.83±7.61)个,t=15.96,P<0.001],侵袭的细胞数量同样显著减少[HepG2:(110.21±12.01)个vs(25.76±4.03)个,t=11.50,P<0.001;Hep3B:(150.22±15.16)个vs(22.03±14.26)个,t=10.65,P<0.001];在SUN475中,过表达LMNB1组比对照组细胞迁移数量显著增加[(50.11±5.55)个vs(349.85±25.26)个;t=11.33,P<0.001],侵袭的细胞数量同样显著增加[(40.11±5.26)个vs(80.13±12.20)个;t=5.21,P=0.007]。与对照组相比,敲低LMNB1后,AKT的磷酸化活性形式p-AKT表达水平显著下降,而过表达LMNB1可导致p-AKT表达升高(P均<0.05)。而敲低或过表达LMNB1后,p-ERK表达水平无显著变化,AKT和ERK的本底表达水平均未发生明显变化。结论抑制LMNB1可通过抑制PI3K/AKT信号转导通路的激活抑制肝癌的发生发展,可作为诊断肝癌的生物标记物和潜在的治疗靶点。展开更多
基金This work is supported by grants from National Key R&D Program of China,No.2017YFA0505302the National Science Foundation of China 21573013,21825401 for Y.S.+1 种基金Chinese National Key Projects of Research and Development,No.2016YFA0100103,Peking-Tsinghua Center for Life SciencesNational Natural Science Foundation of China Key Research Grant 31871266 for C.L。
文摘The eukaryotic genome is folded into higher-order conformation accompanied with constrained dynamics for coordinated genome functions.However,the molecular machinery underlying these hierarchically organized three-dimensional(3D)chromatin architecture and dynamics remains poorly understood.Here by combining imaging and sequencing,we studied the role of lamin B1 in chromatin architecture and dynamics.We found that lamin B1 depletion leads to detachment of lamina-associated domains(LADs)from the nuclear periphery accompanied with global chromatin redistribution and decompaction.Consequently,the interchromosomal as well as inter-compartment interactions are increased,but the structure of topologically associating domains(TADs)is not affected.Using live-cell genomic loci tracking,we further proved that depletion of lamin B1 leads to increased chromatin dynamics,owing to chromatin decompaction and redistribution toward nucleoplasm.Taken together,our data suggest that lamin B1 and chromatin interactions at the nuclear periphery promote LAD maintenance,chromatin compaction,genomic compartmentalization into chromosome territories and A/B compartments and confine chromatin dynamics,supporting their crucial roles in chromatin higher-order structure and chromatin dynamics.
文摘目的探讨核纤层蛋白B1(lamin B1,LMNB1)对肝癌进展的影响,发掘肝癌新的治疗靶点。方法利用工具网站基因表达水平值的交互式分析平台(Gene Expression Profiling Interactive Analysis,GEPIA)分析癌症基因组图谱数据库(The Cancer Genome Atlas,TCGA)中肝癌组织及癌旁组织LMNB1的表达水平,使用Kaplan-Meier分析LMNB1表达水平差异对肝癌患者预后的影响。采用实时定量聚合酶链式反应(polymerase chain reaction,PCR)检测正常肝细胞系及肝癌细胞系中LMNB1表达水平。选取LMNB1表达水平较高的两种人肝癌细胞株Hep3B、HepG2,转染小干扰RNA敲低LMNB1表达,在LMNB1表达水平较低的细胞SUN475中构建LMNB1稳定过表达细胞系并使用Western blot验证转染效率,采用CCK8法检测敲低或过表达LMNB1后肝癌细胞的增殖能力,采用平板克隆形成检测敲低或过表达LMNB1后细胞形成克隆的能力。采用Transwell检测敲低或过表达LMNB1后细胞侵袭及迁移能力的变化。采用Western blot实验检测磷酸化蛋白激酶B(phosphorylated protein kinase B,p-AKT)、蛋白激酶B(protein kinase B,AKT)、磷酸化细胞外调节蛋白激酶(phosphorylated extracellular regulated protein kinases,p-ERK)及细胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)的变化。结果TCGA数据库分析表明肝癌组织中LMNB1表达水平较癌旁正常组织高(P<0.05),且LMNB1表达水平与肝癌患者预后呈负相关(P=0.003)。实时定量PCR显示相对正常人肝细胞系,肝癌细胞中LMNB1 mRNA表达量分别为MHCC97H:1.80±0.10(t=11.08,P<0.001);SUN475:1.29±0.03(t=5.88,P=0.004);HepG2:2.97±0.04(t=39.68,P<0.001);PLC/Prf/5:1.74±0.04(t=14.51,P<0.001);HuH7:1.70±0.02(t=15.22,P<0.001);SK-HEP-1:1.59±0.05(t=11.17,P<0.001);Hep3B:2.27±0.09(t=18.50,P<0.001);均显著高于正常人肝细胞系。Westernblot结果显示在HepG2及Hep3B细胞系中,与siScramble阴性对照组相比,转染siLMNB1实验组的LMNB1表达水平显著降低(HepG2:0.60±0.10 vs 1.60±0.10,t=11.55,P<0.001;Hep3B:0.40±0.10 vs 1.70±0.10;t=15.61,P<0.001);而SUN475中转染质粒后LMNB1表达显著增加(0.70±0.20 vs 0.07±0.04;t=5.541,P=0.005)。敲低LMNB1后培养96 h,与对照组相比,Hep3B(10.81±0.67 vs 15.48±0.62;t=8.86,P<0.001)及HepG2(9.45±0.61 vs17.08±0.75;t=13.67,P<0.001)细胞增殖能力被显著抑制;而在SUN475中过表达LMNB1后,实验组细胞增殖活性显著增加(16.94±1.52 vs 12.65±1.06;t=3.99,P=0.016)。在HepG2及Hep3B细胞系中敲低LMNB1后,细胞克隆形成数显著减少[HepG2:(90.30±7.24)个vs(382.01±25.27)个,t=19.24,P<0.001;Hep3B:(128.03±8.24)个vs(395.85±28.27)个,t=15.76,P<0.001],在SUN475中过表达LMNB1组比对照组克隆形成个数显著增加[(467.82±42.45)个vs(85.31±15.32)个;t=14.87,P=0.001]。在HepG2及Hep3B细胞系中敲低LMNB1后,肝癌细胞迁移数量显著减少[HepG2:(75.25±8.10)个vs(15.02±3.50)个,t=11.90,P<0.001;Hep3B:(168.20±12.26)个vs(34.83±7.61)个,t=15.96,P<0.001],侵袭的细胞数量同样显著减少[HepG2:(110.21±12.01)个vs(25.76±4.03)个,t=11.50,P<0.001;Hep3B:(150.22±15.16)个vs(22.03±14.26)个,t=10.65,P<0.001];在SUN475中,过表达LMNB1组比对照组细胞迁移数量显著增加[(50.11±5.55)个vs(349.85±25.26)个;t=11.33,P<0.001],侵袭的细胞数量同样显著增加[(40.11±5.26)个vs(80.13±12.20)个;t=5.21,P=0.007]。与对照组相比,敲低LMNB1后,AKT的磷酸化活性形式p-AKT表达水平显著下降,而过表达LMNB1可导致p-AKT表达升高(P均<0.05)。而敲低或过表达LMNB1后,p-ERK表达水平无显著变化,AKT和ERK的本底表达水平均未发生明显变化。结论抑制LMNB1可通过抑制PI3K/AKT信号转导通路的激活抑制肝癌的发生发展,可作为诊断肝癌的生物标记物和潜在的治疗靶点。
