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1.
Monoclonal antibody production (mAb) first requires the availability of large amounts of pure immunogen for animal immunisation and fusion screening procedures. To overcome this obstacle, we have developed a simple method for rapid generation of pure antigen by generation of recombinant protein containing the antigen of interest fused to the hinge and Fc domains of human immunoglobulin (Ig). The Fc domain forms a convenient 'tag' to enable detection of the protein in supernatant of transfected cells and for purification of immunogen by protein A affinity chromatography. The only requirement for immunogen preparation using this methodology is that a DNA sequence encoding a portion of the molecule of interest is known and that a suitable PCR template is available. Antibody production can be tailored to specific protein domains, for example functional domains, by expressing solely those domains in the fusion protein. We illustrate the technique with two different fusions used to raise antibodies against the porcine and human analogues of a complement (C) regulatory protein, decay accelerating factor (DAF) (CD55). Use of the specific Ig-fusion protein and a control protein facilitated screening of fusions by ELISA. We demonstrate two expression systems used to generate Ig fusion proteins, the first utilised a commercial vector to incorporate an amino terminal leader sequence and carboxy terminal Ig domains. Low levels of expression required subcloning into a high expression vector and resulted in yields of fusion protein at between 2 and 10 mg per litre of supernatant. The second expression system utilised the high expression vector directly, Ig domains of the chosen immunoglobulin isotype were amplified from peripheral blood mononuclear cell (PBMC) RNA and ligated into the vector in frame with DNA encoding the antigen. We describe potential pitfalls that may be encountered while using Ig fusion proteins as immunogen and demonstrate ways in which to tailor their design for optimal mAb production.  相似文献   

2.
目的实现人补体受体1型功能域SCR1-3基因的克隆、表达及生物学活性鉴定。方法从人外周血中提取总RNA,通过逆转录获得cDNA,PCR扩增获得编码CR1-SCR1-3基因序列;克隆到毕赤酵母分泌表达质粒pPIC9K,构建重组质粒pPIC9K-CR1-SCR1-3,菌落PCR、双酶切鉴定后测序;线性化重组质粒电转化毕赤酵母KM71基因组中,经菌落PCR技术筛选在G418平板上生长的多拷贝阳性转化子;摇瓶发酵和甲醇诱导,SDS-PAGE和Western-blot鉴定目的蛋白表达;镍柱亲和层析纯化目的蛋白;用体外抑制补体溶血反应实验测定目的蛋白的生物活性。结果获得了人CR1-SCR1-3编码区序列,测序结果与与GenBank中的相应序列一致;SDS-PAGE和Western-blot表明目的基因在毕赤酵母中实现了分泌表达;体外实验证实经纯化后的CR1-SCR1-3能够明显抑制补体溶血。结论成功构建重组表达质粒pPIC9K-CR1-SCR1-3,在毕赤酵母中实现了CR1-SCR1-3的分泌表达,该蛋白具有较高的抑制补体生物活性。  相似文献   

3.
Complement system is an important arm of the immune system that promotes inflammation. Complement Factor H (FH) is a critical regulator of the alternative complement pathway. Its absence causes pathology in different organs resulting in diseases such as age related macular degeneration and dense deposit disease. Recent studies suggest that the complement system plays a role in bone development and homeostasis. To determine the role of FH in bone architecture, we studied the FH knockout (fh-/-) mice. 3D reconstructions of femur from 16 week old fh-/- mice reveal significant changes, such as decreased BV/TV (4.5%, p?<?0.02), trabecular number (22%, p?<?0.01), tissue mineral density (16%, p?<?0.04), and increased marrow area (16% p?<?0.01), compared to their wild type (WT) counterparts. Kidney function and histology remained normal indicating that bone changes occurred prior to kidney dysfunction. Next we examined cultured osteoblasts and osteoclasts isolated from bone marrow. FH is expressed ubiquitously in the osteoblasts and in the cytoplasm of osteoclasts. The changes caused by absence of FH include: increase in number of osteoblasts (362%) and osteoclasts (342%), increase in RNA (180%) and protein expression of cathepsin K and increased osteoclast function (pit formation, 233%). Actin rearrangement in both osteoblasts and osteoclasts was altered, with a loss of integrity of the F-actin ring at the periphery of the osteoclasts. For the first time our studies demonstrate a direct role of FH in the maintenance of bone structure and function and is highlighted as a promising therapeutic target in bone diseases.  相似文献   

4.
目的:表达重组人可溶性成纤维细胞生长因子受体1(soluble fibroblast growth factor receptor 1,sFGFR1),研究其对成纤维细胞生长因子(FGF)生物学活性的拮抗作用。方法:采用逆转录-PCR(PT-PCR)技术自人肺成纤维细胞获得sFGFR1 cDNA,测序确证后,将其克隆人酵母细胞表达载体pYEX4T-1;重组质粒转化入酵母细胞(DY150)中进行诱导表达,表达产物经SDS-PAGE及 Western blot鉴定。利用 NIH3T3细胞增殖抑制实验检测重组人 sFGFR1的生物学活性。结果:经 CuSO4诱导,酵母细胞表达出重组谷胱苷肽转移酶(GST)-sFGFR1融合蛋白,此蛋白在凝胶上表现为 1条约 60kD的阳性区带,在 Western blot实验中可被GST特异性抗体识别。重组GST-sFGFR1融合蛋白的粗提物在体外能够桔抗FGF介导的促NIH3T3细胞增殖的活性。结论:重组GST-sFGFR1融合蛋白在酵母表达系统中得到有效表达,并具有很好的生物活性。  相似文献   

5.
Previous reports have shown production of complement components C4, C2 and factor B by renal tissue. We have shown recently that human proximal tubular epithelial cells (PTEC) synthesize C3 in vitro, and that IL-2 enhances this production. In the present study we demonstrate that human mesangial cells (MC) in culture produce factor H and that supernatants of activated peripheral blood mononuclear cells (T cell growth factor (TCGF)) induce C3 production and enhance factor H synthesis in both a time- and dose-dependent manner. To investigate whether certain defined cytokines from TCGF were responsible for the observed effect, we tested various cytokines for their effect on complement production by MC. It is shown that IL-1 induces C3 synthesis whereas factor H production is up-regulated by IFN-gamma, in both a dose- and time-dependent manner. Antibody blocking experiments revealed that C3 synthesis induced by both TCGF and IL-1 could be blocked with antibodies specific for IL-1, and also that TCGF and IFN-gamma enhanced factor H synthesis could both be blocked with antibodies specific for IFN-gamma. Cycloheximide was able to inhibit C3 and factor H production, suggesting de novo synthesis of the proteins. mRNA-polymerase chain reaction (PCR) analysis revealed mRNA encoding for C3 after stimulation with TCGF and IL-1. Factor H genes are constitutively expressed in cultured mesangial cells and its expression is up-regulated by TCGF and IFN-gamma. Northern blot analysis with specific probes for C3 and factor H revealed bands which support the results obtained by PCR analysis.  相似文献   

6.
7.
A large number of proteins and peptides have been identifiedin the endometrium where they are likely to exert local biologicaleffects. These substances may be enzymes, their inhibitors,proteinases, proteinase inhibitors, hormones, or bioactive peptideswith diverse functions. Endometrial function and embryo—endometrialinteractions require synchronized actions between endocrineand local factors. As examples of local factors recent studieson the insulin-like growth factor (IGF) system and placentalprotein 14 (PP14) are reviewed. IGF binding protein-1 (IGFBP-1)and PP14 are products of the secretory phase endometrium: IGFBP-1is produced by decidualized stromal cells and PP14 by glandularepithelial cells. IGFBP-1 may inhibit the action of IGFs atthe endometrial-trophoblastic interphase, and it may also havea role in stromal—epithelial interaction. PP14 has immunosuppressiveproperties, and recent findings indicate that it may play apart in the fertilization process by inhibiting binding of spermatozoato the zona.  相似文献   

8.
目的:构建甲型H1N1流感病毒非结构蛋白NS1真核表达载体并表达其编码蛋白(转染293T细胞)。方法:从江苏首例甲型H1N1流感病毒毒株(A/Nan jing/1/2009(H1N1))提取病毒RNA,采用RT-PCR技术扩增NS1全长基因,将其克隆至pMD18-T Vector中构建pMD18-T-NS1质粒,双酶切pMD18-T-NS1与PXJ40-HA后,构建真核表达载体PXJ40-HA-NS1,经酶切及测序鉴定后将质粒转染到293T细胞中,通过Western blot鉴定NS1蛋白的表达。结果:经双酶切、测序鉴定证实NS1基因的真核表达载体构建成功。West-ern blot法可见NS1基因编码蛋白的成功表达。结论:成功克隆NS1全长基因,并构建了其真核表达载体,该表达载体的构建为后期建立稳定表达NS1蛋白的细胞模型和NS1蛋白功能研究提供了材料。  相似文献   

9.
人胰岛素样生长因子1的真核细胞表达及其鉴定   总被引:1,自引:0,他引:1  
目的 构建人胰岛素样生长因子1(IGF-1)的真核细胞表达质粒。方法 用PCR方法从人的肝细胞cDNA文库中克隆出IGF-1cDNA,然后定向插入真核细胞表达载体pcDNA3中,并用脂质体方法转染COS7细胞。用ELISA法和人胚肺纤维母细胞以及NIH3T3纤维细胞增殖法分别测定转染细胞上清液中IGF-1的含量和生物活性。结果 重组的真核细胞表达质粒pcDNA3-IGF-1所含的IGF-1cDNA序列和插入方向均正确,其转染的COS7细胞分泌较高浓度的IGF-1,并且具有明显促进纤维细胞增殖的能力。结论 本实验所构建的重组真核细胞表达质粒pcDNA3-IGF-1能够高效表达有活性的IGF-1,对进一步研究IGF-1体内表达的生理和病理作用有一定意义。  相似文献   

10.
In order to study the effects of insulin-like growth factor (IGF-I) and insulin-like growth factor binding protein (IGFBP-1) on human granulosa cell proliferation after in vitro fertilization, cells were obtained after oocyte retrieval and cultured in the presence or absence of graded amounts of recombinant IGF-I, purified IGFBP-1 and [3H]thymidine. Physiological concentrations of IGF-I (2-200 ng/ml) were found to stimulate [3H]thymidine incorporation into the cells in a concentration-dependent manner. Half-maximal stimulation of [3H]thymidine incorporation was obtained with 10 ng/ml exogenous IGF-I, which was chosen for suppression experiments with graded amounts of purified IGFBP-1. Suppression of IGF-stimulated thymidine incorporation was observed when 200 ng/ml or more of IGFBP-1 was added to the culture medium. The same concentration of IGFBP-1 also markedly inhibited binding of [125I]iodotyrosyl IGF-I to the cells. It is concluded that: (i) after a refractory period, granulosa cells from hyperstimulated follicles retained their mitogenic activity; (ii) IGF-I is capable of stimulating DNA amplification in granulosa cells; and (iii) IGFBP-1 inhibits the IGF-I stimulated proliferation in these cells. In view of our previous studies showing that IGFBP-1 is synthesized by the granulosa cells as they luteinize, the present results suggest that IGFBP-1 is one of the endogenous factors locally regulating the growth and differentiation of granulosa cells.  相似文献   

11.
目的通过体外结合实验验证EHEC O157:H7内膜素受体偶联细胞骨架蛋白重复片段与人肠上皮细胞IRTKS蛋白SH3结构域之间的相互作用,并制备二者蛋白复合体,为利用晶体学方法研究其相互作用奠定基础。方法将IRTKS蛋白的SH3结构域cDNA序列克隆至pET30a表达质粒,转化BL21(DE3),诱导表达纯化SH3(IRTKS)蛋白;制备TCCP重复片段TC-CP(3R)蛋白;将SH3(IRTKS)与TCCP(3R)按照不同比例混合后,非变性丙烯酰胺凝胶电泳鉴定两者相互结合后产物;利用分子筛层析收集标准蛋白、TCCP(3R)、SH3(IRTKS)和TCCP(3R)-SH3(IRTKS)复合体的出峰体积,回归计算复合物的分子量,分析蛋白相互结合的比例。结果成功克隆表达了SH3(IRTKS)重组质粒;并制备了高纯度的SH3(IRTKS)和TCCP(3R)蛋白;非变性丙烯酰胺凝胶电泳结果证实TCCP(3R)与SH3(IRTKS)发生相互作用形成了蛋白质复合体;复合体的分子量约为33 000,二者相互结合的比例约为1:1。结论本研究为TCCP重复片段与SH3(IRTKS)相互作用提供了直接证据,同时复合体的制备,为利用晶体学研究两者的相互作用奠定了基础。  相似文献   

12.
HIV-1 in contrast to animal retroviruses, is not lysed by human complement, but is readily inactivated by the sera from different animal species. To identify a possible species-specific protection mechanism, HIV-1 was expressed in cells of non-human origin. Recombinant HIV-1 virions that could encode the chloramphenicol acetyltransferase (CAT) protein were produced in African green monkey COS-1 cells, mink cells and, as a control, in human HEp-2 cells and were then used to infect CD4-positive target cells. Analysis of the CAT activity of the target cells' revealed that fresh HIV-1-negative human serum reduced the infectivity of HIV-1 derived from monkey and mink cells five- to tenfold, but had no effect on HIV-1 produced in human cells. In addition, human serum efficiently lysed HIV-1 produced in non-human cells in contrast to HIV-1 originating from human cells, suggesting lysis as an important mechanism of virus inactivation. Mammalian cells are protected against lysis by homologous complement by membrane-bound regulatory molecules. Two of these complement inhibitors, namely decay-accelerating factor (DAF) and, to a lesser extent, CD59 were found on the surface of HIV-1 virions by means of a virus capture assay. Antibodies against DAF, but not against other host cell molecules found on the viral surface, efficiently blocked the resistance of HIV-1 produced in human cells to human complement. These results suggest that the acquisition of DAF during the budding process from human cells protects HIV-1 in a species-specific way against the attack of human complement.  相似文献   

13.
人衰变加速因子的二级结构与B细胞表位预测   总被引:2,自引:0,他引:2  
目的分析预测人衰变加速因子的二级结构特征及B细胞表位。方法比较Chou&Fasman经典方案和基于多重序列比较的PHDsec二级结构预测方案的预测准确率,应用较优方案对DAF的二级结构进行预测分析;运用Hopp&Woods的亲水性方案及PHDacc可及性方案预测DAF的亲水性和可及性,结合DAF的二级结构特征,分析预测DAF的B细胞表位。结果PHDsec方案对SCR的预测准确率明显高于Chou&Fasman方案,DAF的SCR1-4中无α螺旋,仅包含β折叠及袢;推测最可能的抗原表位位于Pro73-Val79、Arg130-Leu139及Glu156-Cys163;SCR1、SCR2与SCR3、SCR4在亲水性及二级结构分布方面具有较大差异。结论研究的分析预测结果将有助于确定DAF的B细胞表位及其生物学活性部位。  相似文献   

14.
Borrelia hermsii, the primary etiological agent of tick-borne relapsing fever in North America, binds the complement regulatory protein factor H (FH) as a means of evading opsonophagocytosis and the alternative complement pathway. The ability of FH-binding protein A (FhbA) to bind FH-like protein 1 (FHL-1) has not been assessed previously. In this study, using a whole-cell absorption assay, we demonstrated that B. hermsii absorbs both FH and FHL-1 from human serum. Consistent with this, affinity ligand binding immunoblot analyses revealed that FH constructs spanning short consensus repeats 1 to 7 and 16 to 20 bind to FhbA. To investigate the molecular basis of the interaction of FhbA with FH/FHL-1, recombinant FhbA truncated proteins were generated and tested for FH/FHL-1 binding. Binding required determinants located in both the N- and C-terminal domains of FhbA, suggesting that long-range intramolecular interactions are involved in the formation and presentation of the FH/FHL-1-binding pocket. To identify specific FhbA residues involved in binding, random mutagenesis was performed. These analyses identified a loop region of FhbA that may serve as a contact point for FH/FHL-1. The data presented here expand our understanding of the pathogenic mechanisms of the relapsing fever spirochetes and of the molecular nature of the interaction between FH/FHL-1 and FhbA.  相似文献   

15.
The 155-kDa complement regulator factor H (FH) is the predominant soluble regulatory protein of the complement system. It acts as a cofactor for the factor I-mediated conversion of the component C3b to iC3b, competes with factor B for a binding site on C3b and C3(H2O) and promotes the dissociation of the C3bBb complex. The primary site of synthesis is the liver, i.e. FH-specific mRNA and protein were identified in both hepatocytes (HC) and Kupffer cells (KC). Previous studies in rat primary HC and KC had shown that the proinflammatory cytokine IFN-gamma influences the balance between activation and inhibition of the complement system through up-regulation of the inhibitory FH. In this study we show that C5a, as a product of complement activation, stimulates the expression of FH-specific mRNA and protein in KC and thus induces a negative feedback. Quantitative-competitive RT-PCR showed an approximate threefold C5a-induced up-regulation of FH. ELISA analyses revealed a corresponding increase in FH protein in the supernatants of KC. The up-regulation of FH was completely inhibited by the C5a-blocking monoclonal antibody 6-9F. Furthermore, an involvement of LPS and IFN-gamma was excluded, which strongly indicates a direct effect of C5a on the expression of FH in KC.  相似文献   

16.
衰变加速因子在非小细胞肺癌中的表达及其临床意义   总被引:1,自引:1,他引:0  
目的 检测衰变加速因子(decay accelerating factor,DAF,CD55)在非小细胞肺癌(non-small cell lung carcinoma,NSCLC)中的表达,分析其表达与临床分期、化疗用药及预后的关系。方法 免疫组化法检测8例NSCLC癌旁组织和36例NSCLC手术标本中DAF的蛋白表达,分析临床资料。结果 免疫组化结果显示36例NSCLC标本中,共有18例(50.0%)表达DAF,其中18例肺鳞癌中有15例(83.3%)表达,而16例肺腺癌中有3例(18.8%)表达,两者有显著差异(P〈0.05);不同的病理分期的DAF免疫组化平均积分光密度表达有显著性差异(P〈0.05);DAF的表达与无病生存期无相关关系(P〉0.05)。结论 NSCLC中有DAF的表达,尤其是肺鳞癌;提示在NSCLC抗体治疗中应同时阻断DAF的免疫抑制效应。  相似文献   

17.
目的:克隆、表达猪链球菌2型四川人源分离株ZYH24细胞外蛋白因子基因片段,分析蛋白活性。方法:根据GenBank S.suis 2 epf基因序列设计引物,克隆ZYH24株epf基因片段并进行序列分析;构建原核表达质粒pGEX4T-2-epf,在大肠杆菌中诱导带有谷胱苷肽转移酶(GST)标签的融合蛋白EF-GST的表达;亲和层析法纯化融合蛋白EF-GST,用凝血酶切除重组蛋白中的GST,获得纯化的EF抗原;SDS-PAGE和Western blot分析诱导表达及纯化的重组蛋白。结果:序列分析表明,获得的epf基因片段长895bp;原核表达的融合蛋白EF-GST分子量约62000,凝血酶处理后的EF抗原分子量约35000,两者均可与制备的EF多克隆抗血清发生特异性反应。结论:成功克隆了人源分离株ZYH24 epf基因片段,在原核系统实现高效的功能性表达,为开展EF蛋白的相关研究奠定了基础。  相似文献   

18.
Microbial pathogens often exploit human complement regulatory proteins such as factor H (FH) and factor H-like protein 1 (FHL-1) for immune evasion. Fba is an FH and FHL-1 binding protein expressed on the surface of the human pathogenic bacterium Streptococcus pyogenes, a common agent of pharyngeal, skin, and soft-tissue infections. Fba has been shown to contribute to phagocytosis resistance, intracellular invasion, and virulence in mice. Here, we look at the role of Fba in recruitment of FH and FHL-1 by five serotype M1 isolates of streptococci. Inactivation of fba greatly inhibited binding of FH and FHL-1 by all isolates, indicating that Fba is a major FH and FHL-1 binding factor of serotype M1 streptococci. For three isolates, FH binding was significantly reduced in stationary-phase cultures and correlated with high levels of protease activity and SpeB (an extracellular cysteine protease) protein in culture supernatants. Analysis of a speB mutant confirmed that SpeB accounts for the loss of Fba from the cell surface, suggesting that the protease may modulate FH and FHL-1 recruitment during infection. Comparisons of fba DNA sequences revealed that the FH and FHL-1 binding site in Fba is conserved among the M1 isolates. Although the ligand binding site is not strictly conserved in Fba from a serotype M49 isolate, the M49 Fba protein was found to bind both FH and FHL-1. Collectively, these data indicate that binding of FH and FHL-1 is a conserved function of Fba while modulation of Fba function by SpeB is variable.  相似文献   

19.
《Molecular immunology》2015,68(2):584-595
The regulators of complement activation gene cluster encodes a group of proteins that have evolved to control the amplification of complement at the critical step of C3 activation. Complement receptor 1 (CR1) is the most versatile of these inhibitors with both receptor and regulatory functions. While expressed on most peripheral blood cells, the only epithelial site of expression in the kidney is by the podocyte. Its expression by this cell population has aroused considerable speculation as to its biologic function in view of many complement-mediated renal diseases. The goal of this investigation was to assess the role of CR1 on epithelial cells. To this end, we utilized a Chinese hamster ovary cell model system. Among our findings, CR1 reduced C3b deposition by ∼ 80% during classical pathway activation; however, it was an even more potent regulator (>95% reduction in C3b deposition) of the alternative pathway. This inhibition was primarily mediated by decay accelerating activity. The deposited C4b and C3b were progressively cleaved with a t½ of ∼ 30 min to C4d and C3d, respectively, by CR1-dependent cofactor activity. CR1 functioned intrinsically (i.e, worked only on the cell on which it was expressed). Moreover, CR1 efficiently and stably bound but didn't internalize C4b/C3b opsonized immune complexes. Our studies underscore the potential importance of CR1 on an epithelial cell population as both an intrinsic complement regulator and an immune adherence receptor. These results provide a framework for understanding how loss of CR1 expression on podocytes may contribute to complement-mediated damage in the kidney.  相似文献   

20.
PROBLEM: In order to investigate the role of macrophage colony-stimulating factor (M-CSF) and monocyte chemoattractant protein -1 (MCP-1) in human ovulation, we studied the regulation of M-CSF and MCP-1 in cultured human granulosa cells. METHOD OF STUDY: Immortalized granulosa cells (GC1a) were cultured in serum-free medium, and incubated with interleukin (IL)-1alpha, IL-1 receptor antagonist (ra) and tumor necrosis factor (TNF)-alpha. The supernatants were collected, and M-CSF and MCP-1 were measured by ELISA. RESULTS: The levels of M-CSF and MCP-1 were increased after treatment with IL-1alpha (1 nm) and TNF-alpha (1 nm) in a time-dependent manner. The levels of M-CSF and MCP-1 were significantly increased after treatment with IL-1alpha and TNF-alpha in a dose-dependent manner. However, the levels of M-CSF and MCP-1 were significantly decreased by treatment with IL-1alpha (1 nm) and/or increasing concentrations of IL-1 ra. CONCLUSIONS: Our data indicated that M-CSF and MCP-1 were regulated by IL-1alpha and TNF-alpha. It was suggested that M-CSF and MCP-1 may play an important role in human preovulatory processes.  相似文献   

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