小鼠次级淋巴组织趋化因子的原核表达及纯化

背景：次级淋巴组织趋化因子(secondary lymphoid-tissue chemokine,SLC/CCL21)是近年来发现的,具有免疫调节作用及抗肿瘤活性。 目的：构建小鼠次级淋巴组织趋化因子原核表达载体,并在大肠杆菌中高效表达重组蛋白。 方法：取C57BL/6小鼠淋巴结细胞,体外用Poly(I:C)刺激后提取RNA并反转录,以此cDNA为模板,通过PCR技术扩增出CCL21成熟蛋白编码序列。克隆入原核表达载体pBEn-SBP-SET1a,构建融合表达载体pBEn-CCL21。将表达载体转化大肠杆菌BL21(DE3),经异丙基-β-D-硫代吡喃半乳糖苷诱导后TRICINE-SDS-PAGE电泳分析和鉴定重组蛋白的表达。CCL21融合蛋白经链霉亲和柱层析纯化。 结果与结论：实验成功构建了CCL21基因的原核表达载体pBEn-CCL21,并获得相应的融合蛋白。结果显示CCL21可在大肠杆菌中高效表达,经链霉亲和柱层析纯化即可获得CCL21重组目的蛋白。     

人IL-31的克隆表达及对表皮角化细胞的影响

目的克隆人IL-31基因,构建真核表达载体,研究人IL-31对表皮角化细胞HaCaT的影响及其作用机制。方法PMA、PHA刺激正常人外周血单个核细胞,提取细胞总RNA,采用RT-PCR克隆人IL-31基因,并将其克隆到真核表达载体pcDNA3.1/myc-His（-）A,进行PCR和双酶切鉴定,并进行序列测定。将重组质粒转染CHO细胞,用RT-PCR和Western blot分析rhIL-31在CHO细胞中的表达。用Ni^2＋树脂纯化his融合蛋白,用不同剂量rhIL-31刺激HaCaT细胞,利用Transwell穿孔板检测HaCaT细胞培养上清对外周血单个核细胞的趋化作用,荧光定量PCR检测rhIL-31对HaCaT表达趋化因子的影响,Western blot检测STAT3磷酸化。结果成功获得全长人IL-31基因,测序正确,经双酶切、PCR和序列测定鉴定,真核表达质粒构建正确,可在CHO细胞中表达;该目的蛋白刺激人表皮角化细胞HaCaT,细胞培养上清对外周血单个核细胞有趋化作用,HaCaT细胞表达趋化因子MDC、TARC、I-309;细胞STAT3磷酸化增加。结论IL-31作用于正常人表皮角化细胞,细胞培养上清对外周血单个核细胞有趋化作用,HaCaT细胞趋化因子表达增加,细胞STAT3磷酸化增加,提示IL-31可通过STAT3发挥作用。     

重组CCL2小鼠黑色素瘤B-16细胞的建立及生物学活性的鉴定

目的：在小鼠黑色素瘤B-16细胞中克隆表达趋化因子CCL2,以进一步研究趋化因子与肿瘤的关系。方法：从小鼠腹腔巨噬细胞中提取总RNA,RT-PCR扩增CCL2 cDNA,将此片段重组于真核表达载体peDNA3.0,脂质体FuGENE6转染鼠黑色素瘤B-16细胞,G-418筛选阳性克隆。结果：RT-PCR和免疫细胞化学鉴定转染B-16细胞中有较强CCL2的表达,体外趋化实验表明重组CCL2有生物学活性。结论：获得有趋化活性的重组CCL2的小鼠黑色素瘤B-16细胞。     

含3C蛋白酶切位点的人CD226胞膜外区Ig融合蛋白的真核表达及应用

目的：构建含3C蛋白酶酶切位点的人CD226(PTA1)分子胞膜外区Ig融合蛋白编码基因的真核表达载体，并进行表达和初步鉴定。方法：将人CD226分子的胞膜外区基因，克隆入含3C蛋白酶靶序列的Ig真核表达载体p-3c—Ig中。测序证实后，转染COS7细胞并进行瞬时表达。表达产物经亲和层析件纯化，并通过免疫荧光染色及3C蛋白酶酶切反应进行鉴定结果：经表达和纯化获得CD226胞膜外区的Ig融合蛋白。该融合蛋白可与表达于ECV304细胞表面的CD226配体有效结合。同时，融合蛋白的Fc段亦经3C蛋白酶切除，从而获得CD226胞膜外区的真核表达分子。结论：成功地获得了含有3C蛋白酶酶切位点的人CD226分子胞膜外区Ig真核表达产物，为进一步对CD226分子进行结构和功能研究，以及X线结晶衍射提供了重要条件。     

人CD40-Ig融合蛋白在CHO细胞中的表达与纯化研究

目的 建立稳定表达CD40－Ig融合蛋白的工程细胞株,获得大量融合蛋白以研究靶向阻断CD40：CD40L途径防治移植物抗宿主病（GVHD）策略的应用潜力。方法 自真核瞬时表达载体pIG／40Ig中切下CD40－Fc融合基因,插入pcDNA3．1载体中构建稳定表达载体。利用脂质体Lipo-fectamine将该载体转染CHO细胞,G418筛选抗性克隆;夹心ELISA法检测上清中CD40－Ig融合蛋白的表达;Westem blot法鉴定其免疫学活性。利用有限稀释法对筛选出的混合克隆单克隆化。滚瓶法无血清大批培养工程细胞,ProteinA亲和层析法纯化,SDS－PAGE后薄层扫描分析纯度。利用流式细胞术检测该蛋白与Jurkat细胞表面CD40L的结合功能。结果 CD40－Fc融合基因插入pcDNA3．1载体后构建成功稳定表达载体p3．1／40Ig,转染CHO细胞后经2次克隆化获得稳定表达CD40－Ig融合蛋白的基因工程细胞株,命名为p3．1／40Ig,转染CHO细胞后经2次克隆化获得稳定表达CD40－Ig融合蛋白的基因工程细胞株,命名为B2。ProteinA亲和层析纯化融合蛋白纯度达95％以上,该融合蛋白可特异结合Jukat细胞表面的CD40L。结论 CD40－Ig融合蛋白可模仿天然分子与其配基结合,为研究靶向CD40：CD40L途径的治疗制剂在防治GVHD中的潜在应用提供了有用的工具。     

人Toll-like receptor 2胞外段的克隆和表达

目的 克隆、表达人Toll-like receptor 2(TLR2)胞外段(A26-T588)基因，获得人TLR2胞外段蛋白。方法 RT-PCR扩增TLR2胞外段基因，以pcDNA3．1 质粒为载体在HEK293细胞中表达TLR2胞外段蛋白，同时以pcDNA3．1 ／TLR2(A26-T588)重组质粒免疫昆明鼠，制备抗TLR2胞外段蛋白多抗。结果 PCR扩增及重组质粒测序结果表明成功地构建了pcDNA3．1 ／TLR2(A26-T588)真核表达质粒，SDS-PAGE分析纯化产物在Mt为68000处出现明显蛋白条带。重组质粒DNA免疫小鼠3次后，血清抗体滴度可达1：250。TLR2胞外段蛋白可与LPS结合，并在一定的质量浓度范围内呈剂量依赖性。结论 构建的pcDNA3．1 ／TLR2(A26-T588)真核表达质粒可在哺乳动物细胞中表达TLR2胞外段蛋白，并与重组质粒DNA免疫小鼠抗血清及TLR2单克隆抗体TL2.1特异性反应，由此证明其表达正确。     

趋化因子配体18重组成熟肽段的表达

目的 构建PET SUMO-CCL18原核表达质粒,并表达、纯化获得重组趋化因子配体18成熟肽段.方法 从人卵巢癌组织中克隆CCL18基因全长,继而扩增表达成熟蛋白质的核酸序列,连接入PET SUMO载体,重组阳性克隆转入感受态细胞BL21(DE3)中IPTG诱导表达,基质辅助激光解吸/电离质谱技术(MALDI-TOF)验证后以SUMO蛋白酶切除载体部分,纯化浓缩,MALDI-TOF鉴定表达结果.结果 测序分析证实,克隆入PET SUMO载体的CCL18序列与Genbank中报道序列完全一致,纯化后蛋白质谱鉴定与天然CCL18成熟蛋白序列一致.结论 成功构建了高表达CCL18蛋白的表达系统,得到重组CCL18成熟肽段,为进一步研究CCL18蛋白在卵巢癌中的作用提供实验基础.     

趋化因子MIP-3α的克隆与表达

目的 克隆人趋化因子MIP-3α基因，表达并初步纯化MIP-3α融合蛋白。方法从扁桃体中提取总RNA，再进行RT-PCR，扩增MIP-3a成熟蛋白基因，并在5’和3’分别添加NcoⅠ和EcoRⅠ酶切位点，通过这两个酶切位点重组于pET32a( )载体上，转化E．coli．DH5α，筛选阳性克隆，酶切鉴定，DNA测序检测插入序列的正确性，缺失突变获得MIP-3α天然蛋白表达载体pET32a( )／MIP-3α，SDS-PAGE分析其表达，Westernblot验证融合蛋白。大量表达并初步纯化MIP-3α融合蛋白。结果 成功克隆了MIP-3α基因，表达并初步纯化得到MIP-3α融合蛋白。结论构建的MIP-3α硫氧还蛋白融合表达载体以可溶性蛋白的方式表达MIP-3α硫氧还蛋白。     

重组分泌型人CREG/myc-His融合糖蛋白的表达及功能分析

目的：构建人E1A激活基因阻遏子（Human cellular repressor of E1A-stimulated gene，hCREG）基因的真核表达载体并转染人293F细胞株，筛选稳定转染细胞克隆，鉴定重组的分泌型hCREG／myc．His融合蛋白的糖基修饰和生物学功能。方法：用RT-PCR技术扩增终止密码突变的hCREG开放读码框并构建pcDNA4myc．His／hCREG真核表达载体；Lipofeetamine2000转染人293F细胞株并筛选稳定表达细胞克隆，去血清法诱导重组蛋白表达；应用Westernblot方法鉴定分泌型hCREG／myc-His融合蛋白的表达，糖苷酶法及Westernblot行hCREG／myc-His融合蛋白的糖基化分析；用流式细胞周期分析分泌型hCREG／myc．His融合蛋白对体外培养的人胸廓内动脉平滑肌细胞（HITASY）增殖能力的影响。结果：RT-PCR扩增含终止密码突变的hCREGeDNA片段，经BamHⅠ和EcoRⅠ双酶切构建了pcDNA4myc．His／hCREG真核表达载体，酶切及测序结果证实构建的重组质粒正确；Westernblot证实转染pcDNA4myc．His／hCREG的293F细胞克隆可以稳定表达并分泌hCREG／myc-His融合蛋白；糖苷酶分析证实分泌型hCREG／myc-His融合蛋白是糖基化蛋白；流式细胞周期分析证实与正常培养HITASY细胞比较，添加含有分泌型hCREG／myc-His糖蛋白上清的H1TASY细胞出现明显的G1期细胞周期阻滞现象（58．88％vs62．89％，P〈0．005）。结论：构建了pcDNA4myc-His／hCREG真核表达载体并表达了具有生物学功能的分泌型重组hCREG／myc-His糖蛋白。     

带组氨酸标签的癌蛋白SET真核表达载体的构建及其表达

目的为研究三氯乙烯诱导的差异蛋白SET在肝细胞L-02中的相互作用,构建了癌蛋白SET和His标签融合表达的真核表达载体pcDNA3．1（＋）／SET—His。方法从L-02肝细胞中提取总RNA,采用RT-PCR扩增SET—His基因并进行双酶切,序列纯化后定向克隆至pcDNA3．1／zeo（＋）载体,阳性克隆载体进行双酶切和测序鉴定．阳性克隆载体瞬时转染入L-02肝细胞,利用Western blotting检测SET—His融合蛋白的表达。结果利用RT—PCR从L-02细胞总RNA中成功克隆出SET基因,经双酶切和测序鉴定证实pcDNA3．1（＋）／SET—His真核表达载体构建成功。经Western blotting验证表明,SET—His融合蛋白在肝细胞中获得高效表达。结论该结果为研究SET蛋白相互作用以及三氯乙烯致机体损伤的机理奠定了基础。     

Isolation and characterization of a novel HS1 SH3 domain binding protein, HS1BP3

We have isolated a novel gene, HS1BP3, which encodes an HS1 binding protein. Analysis of HS1BP3 cDNA indicates several potentially important segments, including a PX domain, a leucine zipper, immunoreceptor tyrosine-based inhibitory motif-like motifs and proline-rich regions. HS1BP3 associates with HS1 proteins in vivo as confirmed by immunoprecipitation in B and T cell lines. HS1BP3 preferentially associates with the HS1 SH3 domains rather than with other SH3 molecules, suggesting a role of HS1BP3 as an HS1 signaling mediator. Overexpression of mutant HS1BP3 protein in T cell lines results in decreased IL-2 production. Our data suggest a novel role for HS1BP3 in lymphocyte activation.     

Recombinant non-structural 1 (NS1) protein of dengue-2 virus interacts with human STAT3beta protein

A combination of yeast two-hybrid library screening, co-immunoprecipitation and immunofluorescence microscopy demonstrated that dengue-2 virus non-structural 1 (NS1) protein can interact with an N-terminally truncated form of human STAT3beta (DeltaN40-STAT3beta) protein. The NS1 protein interacted with the activated STAT3beta protein in vesicle-like structures in the cell cytoplasm. In addition, transfection of dendritic cells with plasmid expressing NS1 protein also resulted in significant induction of tumor necrosis factor-alpha (TNFalpha) and interleukin-6 (IL-6). Since the STAT3beta protein is an acute-phase response factor, its interaction with NS1 protein may influence the pathological changes observed in dengue fever, dengue hemorrhagic fever and dengue shock syndrome.     

Inhibition of M-tropic HIV-1 infection by the fd phage-gene 3 protein with MIP-1α-binding activity

CCR5 is a chemokine receptor with seven transmembrane-domains. It is expressed on T cells and macrophages and functions as the principal co-receptor for macrophage (M)-tropic strains of HIV-1. The anti-CCR5 monoclonal antibody (mAb) 2D7 inhibits the binding and chemotaxis of the three natural β-chemokine ligands of CCR5, macrophage inflammatory protein (MIP)-1α, MIP-1β, and RANTES, to CCR5⁺ cells. The mAb also efficiently blocks the infectivity of several M-tropic and dual-tropic HIV-1 strains in vitro.In this study, we attempted to determine the peptide motif recognized with the 2D7 mAb. We isolated phage clones by panning a phage display library using 2D7 and identified three peptide motifs. One of these phage clones (M23) showed a marked inhibitory activity on HIV-1 infection. The unique sequence of 15 amino acids with an internal disulfide bond was inserted in the g3p of the M23 phage clone (M23-g3p). The M23-g3p was purified by fast-performance liquid chromatography (FPLC). We show here that (1) M23-g3p was specifically recognized with anti-CCR5 mAb; (2) M23-g3p showed inhibitory activity on the infectivity of M-tropic but not T-tropic HIV-1 strains; (3) M23-g3p bound to MIP-1α, MIP-1β, and RANTES but not MCP-1. These results suggested that the M23-g3p might mimic the CCR5-binding domain shared by β-chemokines, MIP-1α, MIP-1β, and RANTES as well as the HIV-1 infection.     

Uncoupling protein 1 and 3 polymorphisms are associated with waist-to-hip ratio

Body weight regulation is a complex phenotype also depending on the action of uncoupling proteins (UCPs) that mediate the "uncoupling" of respiration leading to the dissipation of energy as heat. This study investigated whether genetic variants in the genes encoding UCP-1 and UCP-3 are associated with different obesity-related phenotypes in 162 whites with a wide range of body mass index. All subjects were genotyped for the polymorphisms UCP-1 A-3826G, UCP-1 Ala64Thr, and UCP-3 C-55T using a PCR-based restriction method with appropriate enzymes. The frequencies of the UCP-1 3826G, UCP-1 64Thr, and UCP-3 55T alleles were 27.2%, 12.0%, and 22.8%, respectively. No significant associations were observed between polymorphism and body mass index or obesity. However, after adjustment for gender, age, body mass index, and diabetes mellitus the waist-to-hip ratio was significantly associated with UCP-1 Ala64Thr ( P=0.003) and UCP-3 C-55T ( P=0.02) but not with UCP-1 A-3826G. The higher waist-to-hip ratios associated with the UCP-1 64Thr and UCP-3 55T alleles were due to higher waist circumference in these allele carriers. In conclusion, central obesity in whites as reflected by an increased waist-to-hip ratio is associated with the UCP-1 Ala64Thr and UCP-3 C-55T polymorphisms. To what extent these genotypes contribute to the overall cardiovascular risk remains to be elucidated.     

A protein assay program for Lotus 1-2-3

Protein assays have become a widespread procedure not only in biochemistry but in many disciplines. This paper describes a program that takes advantage of the capacity of a spreadsheet program such as Lotus 1-2-3 to produce a graph and perform the calculations necessary for such assays. Its simplicity allows users with little or no experience with Lotus 1-2-3 to run it once installed.     

In vitro interaction between coxsackievirus B3 VP1 protein and human pleckstrin homology domain retinal protein (PHR1)

Coxsackievirus B3 (CVB3) infection causes central nervous system diseases including aseptic meningitis and encephalitis. To understand the mechanism of this virus, a yeast two-hybrid system was used to screen cellular proteins from a human heart cDNA library. The results revealed that the human Pleckstrin Homology Domain Retinal protein (PHR1), a PH domain-containing protein with low expression in the heart and high expression in the brain, interacts with CVB3 VP1, a major structural protein of CVB3. Yeast mating assays and in vitro coimmunoprecipitation verified the interaction between CVB3 VP1 and PHR1. An α-galactosidase assay indicated that of α-galactosidase activity was higher in positive clones than in controls suggesting a strong interaction. Furthermore, assay of deletion mutants defined the minimal region of PHR1 required for its interaction with VP1 as amino acids 95–172 and two regions of VP1 required for its interaction with PHR1 as amino acids 729–767 and 811–859. The results revealed multiple binding sites between PHR1 and CVB3 VP1 and suggested that the strong interaction between these two proteins might play an important role in central nervous system disease in the human brain.     

A novel virus-encoded nucleocytoplasmic shuttling protein: the UL3 protein of herpes simplex virus type 1

Herpes simplex virus type 1 (HSV-1) UL3 protein is a nuclear protein. In this study, the molecular mechanism of the subcellular localization of UL3 was characterized by fluorescence microscopy in living cells. A nuclear localization signal (NLS) and a nuclear export signal (NES) were also identified. UL3 was demonstrated to target to the cytoplasm through the NES via chromosomal region maintenance 1 (CRM-1) dependent pathway, and to the nucleus through RanGTP-dependent mechanism. Heterokaryon assays confirmed that UL3 was capable of shuttling between the nucleus and the cytoplasm. These results demonstrate that the UL3 protein is a novel HSV-1 encoded nucleocytoplasmic shuttling protein.     

Stoichiometry of the antiviral protein APOBEC3G in HIV-1 virions

A host cytidine deaminase, APOBEC3G (A3G), inhibits replication of human immunodeficiency virus type 1 (HIV-1) by incorporating into virions in the absence of the virally encoded Vif protein (Deltavif virions), at least in part by causing G-to-A hypermutation. To gain insight into the antiretroviral function of A3G, we determined the quantities of A3G molecules that are incorporated in Deltavif virions. We combined three experimental approaches-reversed-phase high-pressure liquid chromatography (HPLC), scintillation proximity assay (SPA), and quantitative immunoblotting-to determine the molar ratio of A3G to HIV-1 capsid protein in Deltavif virions. Our studies revealed that the amount of the A3G incorporated into Deltavif virions was proportional to the level of its expression in the viral producing cells, and the ratio of the A3G to Gag in the Deltavif virions produced from activated human peripheral blood mononuclear cells (PBMC) was approximately 1:439. Based on previous estimates of the stoichiometry of HIV-1 Gag in virions (1400-5000), we conclude that approximately 7 (+/-4) molecules of A3G are incorporated into Deltavif virions produced from human PBMCs. These results indicate that virion incorporation of only a few molecules of A3G is sufficient to inhibit HIV-1 replication.     

红细胞带Ⅲ蛋白C1肽链的纯化及其功能的初步研究

目的：研究红细胞带Ⅲ蛋白Ｃ１肽链（带Ⅲ蛋白Ａｌａ８９３－Ｖａ１９１１）的特性及其功能。方法：以１００ｍｍｏｌ／ＬＮａＯＨ预处理红细胞膜血影，再用胰蛋白酶消化，采用高效液相色谱（ＨＰＬＣ）及氨基酸测序仪分析检定了从红细胞血影中释放的多肽，并纯化了带Ⅲ蛋白Ｃ１肽链，以不同浓度的Ｃ１肽链与新鲜的红细胞血影进行温浴。结果：Ｃ１肽链与红细胞内的新蛋白酶活性有关。