乙型肝炎病毒X蛋白通过降低P4启动子甲基化水平上调人IGF-II基因的转录

目的:构建稳定表达乙型肝炎病毒X蛋白(HBx)的肝癌细胞株HepG2-HBx,探讨HBx对胰岛素样生长因子 II(IGF-II)基因P4启动子甲基化水平及转录表达的影响。方法:应用基因重组技术,构建含HBx基因的重组逆转录病毒载体pBABE-puro-HBx,采用磷酸钙共沉淀法将其转染293FT包装细胞产生逆转录病毒,感染HepG2肝癌细胞,采用嘌呤霉素进行阳性克隆筛选,Western blotting鉴定表达HBx蛋白的肝癌细胞株HepG2-HBx。采用亚硫酸氢盐测序法及实时荧光定量RT-PCR检测HepG2-HBx细胞中P4启动子甲基化水平及P4 mRNA表达水平变化。进一步将体外甲基化的人IGF-II基因P4启动子驱动的荧光素酶报告载体pGL3-P4及含HBx基因的pCMV-tag2B-X质粒共转染HepG2肝癌细胞,采用亚硫酸氢盐测序法及双萤光素酶实验检测pGL3-P4载体上P4启动子甲基化水平及转录调控活性变化。结果:(1)经Western blotting鉴定,成功构建了稳定表达HBx蛋白的肝癌细胞株HepG2-HBx;(2)表达HBx蛋白的HepG2-HBx细胞中P4启动子甲基化CpG位点的比例(9.0%)明显低于对照细胞HepG2-control(25.0%)(P<0.01),而其P4 mRNA表达水平则为对照细胞HepG2-control的2.8倍;(3)共转染pCMV-tag2B-X质粒的HepG2细胞中pGL3-P4载体上P4启动子甲基化CpG位点的比例(60.8%)明显低于共转染对照质粒pCMV-tag2B的HepG2细胞(84.1%)(P<0.01),而前者P4启动子相对萤光素酶活性(14.12±0.89)则明显高于后者(4.61±0.76)(P<0.01)。结论:HBx蛋白可降低IGF-II基因P4启动子甲基化水平,进而上调其转录表达。     

蛋白激酶PKR的克隆表达及与其相互作用的蛋白质的亲和纯化

目的:克隆并表达双链RNA调节的蛋白激酶(PKR)基因,以纯化分离与PKR相互作用的蛋白质。方法:设计特异性引物,PCR扩增分别得到FLAG-PKR-HA和HA-PKR-FLAG基因片段,克隆至表达载体pSG5中。将重组质粒通过脂质体法转染PKR稳定沉默(PKRkd)的HeLa细胞,Western blot检测PKR及标签表达情况;最后,利用HA、FLAG串联亲和纯化系统(TAP)纯化分离与PKR相互作用的蛋白,Western blot技术及银染SDS-PAGE验证PKR蛋白复合物的纯化和分离情况。结果:成功构建了PKR融合蛋白表达载体及FLAG、HA亲和纯化系统,SDS-PAGE和银染结果显示TAP系统分离得到了PKR蛋白带和两条可能与PKR相互作用的蛋白质片段。结论:成功纯化和分离了与PKR相互作用的蛋白质,为进一步研究奠定了基础。     

RORγt蛋白复合体在Th17细胞分化中的“阴-阳”调节

Th17细胞是诱导组织炎症反应的辅助性T细胞,而维甲酸相关孤核受体γt(RORγt)是Th17细胞的主要转录因子(TF)。目前普遍认为转录因子不会单独发挥功能,因此RORγt会形成介导Th17细胞分化的蛋白复合体。鉴于RORγt及其潜在复合体在Th17细胞发育和功能中的重要性,本综述总结了近期有关RORγt和潜在伙伴蛋白之间相互作用的进展,特别讨论了导致Th17细胞分化的机制及其炎症反应疾病中的潜在临床干预靶点。     

RORγt基因启动子的鉴定和特征分析

目的以RORγt转录起始位点5’上游4.8 kb基因序列为研究对象,初步鉴定分析是否存在RORγt单独的启动子,并且探讨β-Catenin/Tcf1信号途经对RORγt启动子转录活性的影响。方法用带有不同长度的5’上游基因的5个报告质粒,与pSV-40-renilla Luc共转染Jurkat、EL-4、NIH 3T3和293T细胞系,与报告质粒的空载相比较,根据荧光强度的相对值的大小确定启动子存在的可能性和所在的位置;利用野生型β-Catenin、激活突变型β-Catenin和Tcf1表达质粒及RORγt启动子报告载体共转染,观察β-Catenin/Tcf1信号途径对RORγt启动子活性的影响。结果不同长度的启动子报告质粒在Jurkat、EL-4、NIH 3T3和293T细胞中均呈现启动子活性,其中所有报告质粒在Juakat和EL-4等T细胞系中的活性均高于其他2个上皮细胞系,而RORγt上游0.5 kb的报告质粒启动子活性在所有的细胞系中均呈最高活性。野生型β-Catenin、激活突变型β-Catenin和Tcf1对RORγt启动子报告有强激活作用。结论 RORγt转录表达由独立启动子控制,β-Catenin/Tcf1信号途径能够增强该启动子的转录活性。     

红系分化相关基因相互作用蛋白质的分离与鉴定

目的制备红系分化相关基因(erythroid differentiation-associated gene,EDAG)蛋白的单克隆抗体,利用免疫沉淀联合质谱技术对EDAG相互作用蛋白质进行分离与鉴定。方法构建EDAG原核表达载体,通过诱导、表达、纯化获得EDAG融合蛋白,杂交瘤技术建立分泌EDAG单克隆抗体的杂交瘤细胞株,利用Western印迹筛选阳性杂交瘤细胞,免疫小鼠得腹水,最后用免疫共沉淀与质谱联合鉴定EDAG相互作用蛋白。结果纯化获得EDAG重组蛋白,筛选出4株分泌EDAG单克隆抗体的杂交瘤细胞株,并制备了腹水。该抗体均可用于内源EDAG蛋白的检测,其中两种抗体可用于免疫共沉淀实验,运用质谱技术筛选获得EDAG候选相互作用蛋白。结论利用EDAG单克隆抗体,筛选到EDAG候选相互作用蛋白质13种,涉及细胞增殖及转录等过程,为EDAG的功能研究及其分子机制的阐明提供了新的线索。     

转录因子JunB在肝癌细胞中的表达、定位及其转录作用研究

目的:构建表达转录因子JunB的真核表达质粒,观察外源JunB分子在细胞中的表达、亚细胞定位及其对下游分子的转录调控作用。方法:采用PCR方法从人源肝cDNA文库中扩增JunB基因片段,克隆入T载体进行测序鉴定。而后将测序正确的基因片段分别亚克隆入pcDNA3.1(-)和pEGFP-C3真核表达载体中,获得重组载体pcDNA-JunB和pEGFP-JunB。采用脂质体瞬时转染法分别将pEGFP-JunB和pcDNA-JunB导入肝癌细胞HepG2中,用Westernblot法观察外源JunB在肝癌细胞中的表达;用荧光显微镜观察其在细胞内的定位;用双荧光素酶报告基因检测法观察JunB对下游靶分子VEGF的转录调控作用。结果:分别构建表达转录因子JunB和增强型绿色荧光蛋白融合JunB分子的重组表达质粒,并经KpnI/BamHI双酶切鉴定正确。将重组表达质粒转染HepG2细胞后,经免疫印迹法和荧光显微镜检测,可见外源导入的JunB分子在细胞中成功表达并特异性定位定位于细胞核内。荧光素酶报告系统检测显示:JunB对VEGF分子在转录水平具有明显的激活作用。结论:成功构建了增强型绿色荧光蛋白基因和转录因子JunB基因融合表达的重组质粒。在肝癌细胞中观察到外源瞬时表达的JunB定位于细胞核中,提示其可能发挥转录因子的活性。报告基因结果显示其对肿瘤血管生成密切相关的分子VEGF发挥转录激活的作用,提示JunB分子有可能成为抑制肝癌血管生成的新靶点。     

ATF-2基因RNA干扰表达载体的构建及鉴定

目的:构建活化转录因子2(ATF-2)基因RNA干扰的真核表达载体,观察其对HepG2肝癌细胞株增殖及凋亡的影响。方法:根据ATF-2 mRNA序列,合成两条寡聚DNA片段,退火后克隆入质粒载体PBA-siU6,DNA测序鉴定重组质粒PBA-siATF-2。脂质体介导质粒转染HepG2细胞。Westernblot法检测ATF-2蛋白表达;MTT方法检测细胞增殖率,流式细胞术(FCM)检测细胞凋亡率。结果:ATF-2基因RNA干扰载体经测序分析证实插入64 bp序列正确无误;Westernblot法显示干扰组细胞内ATF-2蛋白表达量明显降低;ATF-2基因的下调导致HepG2细胞增殖阻滞和凋亡发生。结论:成功构建了ATF-2基因RNAi真核表达载体,下调HepG2细胞ATF-2基因表达,抑制细胞增殖,诱导细胞凋亡。     

HBV preS2S-rhGM-CSF融合基因表达质粒的构建和表达

目的：研究GM-CSF和preS2对乙肝DNA疫苗的免疫增强作用。方法：采用PCR方法，扩增HBV preS2 S基因约846 bp的片段和rhGM-CSF(包括甘氨酸接头)基因450bp的片段。通过T-A克隆技术和基因定向克隆，构建融合基因的真核表达质粒pcDNA3．1-S2S-rhGM-CSF，并在HepG2细胞中表达。结果：经酶切、PCR及DNA测序鉴定，融合基因表达质粒HBV preS2S-rhGM-CSF成功地构建。将其转染HepG2细胞后，目的基因的转录通过RT-PCR得到证实，而且表达的融合蛋白能与抗-HBs、抗-preS2和抗-GM-CSF单克隆抗体(mAb)均产生特异性反应。结论：融合基因表达载体pcDNA3．1-S2S-rhGM-CSF的成功构建并表达，为进一步研究乙肝DNA疫苗奠定了实验基础。     

人组蛋白H3真核表达载体的构建及功能初步检测

目的构建带myc标签的人组蛋白H3基因真核表达载体,获得Myc-H3融合表达蛋白,并对其功能进行初步检测。方法采用PCR技术从乳腺文库中扩增人H3基因编码序列,将其正确插入pXJ-40-myc载体,重组质粒转染人胚肾293T细胞,Western blot法检测融合蛋白表达,通过免疫共沉淀技术检测融合蛋白与已知结合蛋白组蛋白赖氨酸特异性去甲基化酶(LSD1)和组蛋白甲基转移酶(EZH2)的相互作用。结果构建得到组蛋白H3基因的真核表达载体,双酶切鉴定得到与预期片段大小相符的外源基因插入片段,经测序与目的序列完全一致;经Western blot法检测,融合蛋白成功表达;免疫共沉淀检测证实Myc-H3融合蛋白可以和已知相互作用蛋白LSD1及EZH2相互作用。结论成功构建组蛋白H3真核表达载体,该融合蛋白正确表达。     

丙型肝炎双移位F蛋白抑制肝癌细胞p16、p21的表达

目的:探讨丙型肝炎双移位F(DF)蛋白对肝癌细胞抑癌基因p16、p21转录与表达的影响。方法:PCR扩增HCV1b型DF基因,构建pCDNA3.0/HCV-DF真核表达载体。再转染至肝癌细胞HepG2中,G418筛选稳定表达细胞株,Western blot检测p16、p21蛋白表达及半定量RT-PCR法检测p16、p21基因转录,并以pCDNA3.0空质粒作为阴性对照。结果:重组质粒pCDNA3.0/HCV-DF蛋白在HepG2细胞中稳定表达,pCDNA3.0/HCV-DF转染细胞中p16、p21 mR-NA转录水平和蛋白表达水平较空质粒转染的细胞明显下降。结论:HCV-DF蛋白能够抑制p16、p21表达,提示可能参与肝细胞癌变发生发展。     

Regulated expression of nuclear receptor RORγt confers distinct functional fates to NK cell receptor-expressing RORγt(+) innate lymphocytes

Whether the recently identified innate lymphocyte population coexpressing natural killer cell receptors (NKRs) and the nuclear receptor RORγt is part of the NK or lymphoid tissue inducer (LTi) cell lineage remains unclear. By using adoptive transfer of genetically tagged LTi-like cells, we demonstrate that NKR?RORγt(+) innate lymphocytes but not NK cells were direct progenitors to NKR(+)RORγt(+) cells in vivo. Genetic lineage tracing revealed that the differentiation of LTi-like cells was characterized by the stable upregulation of NKRs and a progressive loss of RORγt expression. Whereas interleukin-7 (IL-7) and intestinal microbiota stabilized RORγt expression within such NKR-LTi cells, IL-12 and IL-15 accelerated RORγt loss. RORγt(+) NKR-LTi cells produced IL-22, whereas RORγt? NKR-LTi cells released IFN-γ and were potent inducers of colitis. Thus, the RORγt gradient in NKR-LTi cells serves as a tunable rheostat for their functional program. Our data also define a previously unappreciated role of RORγt? NKR-LTi cells for the onset or maintenance of inflammatory bowel diseases.     

Tubulin和HSP90在氧化应激预适应中的作用

目的：探讨热休克蛋白90和细胞骨架蛋白tubulin在氧化应激预适应中的作用。方法:应用不同浓度H2O2作用于HepG2细胞,建立HSP90不同表达量的模型后,MTT比色法检测细胞活力,Western blotting 定量检测各模型中HSP90、tubulin量,激光扫描共聚焦显微镜测定该两种蛋白在对照、预适应、氧化应激、预适应后氧化应激下的分布和共定位。 结果:MTT比色法结果提示预适应可提高应激状态下的细胞生存活力;Western blotting结果显示氧化应激预适应可提高细胞内HSP90 和 tubulin含量,减轻再次应激所致的HSP90 和 tubulin总量下降;激光共聚焦显示该两种蛋白有相似的细胞分布。结论:Tubulin可能协同HSP90在氧化应激预适应中起保护作用。     

Specific expression of human interferon-gamma controls hepatitis B virus replication in vitro in secreting hepatitis B surface antigen hepatocytes

Interferon-gamma (IFN-γ) has been reported to have antiviral activity against Hepatitis B virus (HBV) and to suppress HBV replication noncytolytically in vivo. Since systemic administration of IFN-γ may cause severe adverse effects, studies of the effects of liver-specific IFN-γ expression from adenoviral vectors in vivo have been investigated. In this study, a novel strategy has been described that drives specific expression of human IFN-γ in HBsAg-secreting hepatocytes. A bicistronic expression vector has been developed, pcDNA3.1-HBV antisense S gene-HCV core protein gene-HCV internal ribosome entry sites (IRES)-IFN-γ (pcDNA-SCIγ), by inserting four DNA fragments into pcDNA3.1. Tight modulation of HCV IRES-dependent translation by the HCV core protein was achieved using an antisense RNA technique with a bicistronic expression vector. HepG2 cells and HepG2.2.15 cells stably expressing HBV were transduced with pcDNA-SCIγ to test the responsiveness of IFN-γ to HBsAg expression. Gene transfer resulted in a low background and a 30-fold induction of IFN-γ expression from pcDNA-SCIγ in a cell-specific fashion. Hepatocyte-specific IFN-γ expression controlled effectively HBV replication in HBsAg-secreting HepG2.2.15 cells without cell toxicity.     

Suppression of furin by interferon-γ and the impact on hepatitis B virus antigen biosynthesis in human hepatocytes

The roles of furin and intrahepatic cytokines in chronic heptatitis B virus (HBV) infection remain largely unknown. Here, we examined the relations between furin, IL-10, IL-12β, interferon (IFN)-γ, programed death (PD)-1, programed death ligand (PD-L)1, and the suppression of hepatitis B e antigen (HBeAg) and surface antigen (HBsAg) biosynthesis. Liver biopsies were performed on 20 chronically HBV-infected (15 HBeAg-positive and 5 HBeAg-negative) patients to assess liver inflammation/fibrosis, and mRNA levels of furin, IL-10, IL-12β, IFN-γ, PD-1, and PD-L1 were assessed by quantitative real-time PCR. IFN-γ mRNA abundance was associated with lower furin mRNA levels and higher PD-1 and PD-L1 mRNA levels in liver tissue from HBeAg-positive patients. IL-10 and IL-12β mRNA levels positively correlated with IFN-γ expression levels (P < 0.05). PD-L1 and furin mRNA levels were further assessed in IFN-γ-stimulated hepatoma cell lines with (HepG2.2.15 cells) and without (HepG2 and Huh7 cells) HBV replication. IFN-γ enhanced PD-L1 expression in hepatoma cells. In HepG2.2.15 cells, IFN-γ further suppressed furin and HBeAg expression. Furin inhibition and knockdown in HepG2.2.15 cells also down-regulated HBeAg and HBsAg biosynthesis. These data suggest that IFN-γ modulates the inflammatory response to avoid excessive hepatocyte damage through the enhancement of PD-1/PD-L1 expression, whereas furin suppression may contribute to a reduction in HBeAg/HBsAg biosynthesis.     

固有免疫调控蛋白PKR串联亲和纯化系统的建立及应用

目的 构建固有免疫调控蛋白--双链RNA(dsRNA)调控的蛋白激酶(PKR)的串联亲和纯化系统(TAP),初步研究PKR蛋白功能,以用于与PKR相互作用的新蛋白的鉴定与功能分析.方法 通过PCR扩增PKR目的基因,克隆至真核表达载体pcTAP-A中.将重组质粒pcTAP-PKR通过脂质体法转染PKR稳定沉默(PKRk...     

乙型肝炎病毒上调HepG2细胞表面HLA-I表达的机制

目的 :探讨HBV野生株 (WT)及核壳蛋白变异株L97、V6 0上调HepG2细胞表面HLA I表达的机制。方法 :将已构建的重组表达载体EBO WT、EBO L97及EBO V6 0 ,分别经脂质体介导转染HepG2细胞 ,以空载体EBO作为对照。用RT PCR半定量法 ,检测细胞内HLA A基因及抗原提呈相关基因LMP2、TAP1和tapasinmRNA的表达 ;用Westernblot测定细胞内HLA I蛋白的表达。结果 :3株HBV重组表达载体转染的细胞 ,均呈现明显的HLA AcDNA的PCR扩增条带及HLA I蛋白条带 ,但其条带的强度有差异 ,EBO L97、EBO WT和EBO V6 0依次减弱。TAP1cDNA扩增带清晰 ,3株HBV间无明显差别。对照细胞未呈现HLA A的条带和仅呈现微弱的TAP1扩增带。各转染细胞均未检出LMP2及tapasinmRNA的表达。 结论 :HBV能诱导HepG2细胞内HLA I分子的合成量 ,使TAP1基因转录增强 ,HLA I的表达上调。核壳蛋白变异株L97和V6 0 ,可使宿主细胞内HLA ImRNA和其蛋白的表达水平发生变化     

The role of alkaline phosphatase in intracellular lipid accumulation in the human hepatocarcinoma cell line,HepG2

Inhibition of tissue non-specific alkaline phosphatase (TNALP) decreases intracellular lipid accumulation in human preadipocytes and the murine preadipocyte cell line, 3T3-L1. Therefore, the current study was performed to determine if TNALP is required for intracellular lipid deposition in the human hepatocyte cell line, HepG2. Intracellular lipid accumulation, TNALP activity and peroxisome proliferator activated receptor (PPAR) γ gene expression were measured in HepG2 and 3T3-L1 cells in the presence and absence of the TNALP inhibitors levamisole and histidine. Sub-cellular TNALP activity was localized using cytochemical analysis. Both PPARγ gene expression and TNALP activity increased during intracellular lipid accumulation in HepG2 and 3T3-L1 cells. Inhibition of TNALP blocked intracellular lipid accumulation but did not alter expression of the PPARγ gene. In HepG2 cells, TNALP co-localized with adipophilin on the lipid droplet membrane. These data suggest a role for TNALP in lipid droplet formation, possibly downstream from PPARγ, within HepG2 and 3T3-L1 cells.