ZNF580-EGFP融合蛋白的亚细胞定位研究

目的：构建增强型绿色荧光报告蛋白(EGFP)与人ZNF580融合蛋白的真核表达载体，转染MGC803细胞进行表达，研究ZNF580-EGFP融合蛋白在MGC803细胞的亚细胞定位。方法：利用PCR技术扩增ZNF580基因cDNA开放阅读框架全编码区、N端编码区、C端编码区，分别克隆到真核表达载体pEGFP-C1，BglⅡ及HindⅢ双酶切电泳筛选、鉴定并测序。荧光显微镜下观察ZNF580-EGFP在MGC803细胞中的表达及亚细胞定位。结果：酶切pEGFP-ZNF580(1-172)、pEGFP-ZNF580(1-93)、pEGFP- ZNF580(94-172)，电泳分析插入片段长度分别为：526 bp、289 bp、247 bp，经连接点两端进行测序证实连接正确。pEGFP-ZNF580(1-172)、pEGFP-ZNF580(94-172)表达的ZNF580-EGFP融合蛋白定位在MGC803细胞核。结论：成功构建真核表达载体并在MGC803细胞中得到表达，分析其核定位信号可能位于ZNF580蛋白的C端C2H2型锌指主构域94-172位氨基酸区间。     

IL-13及其变异体真核表达载体的构建表达与亚细胞定位

目的：体外构建野生型人白细胞介素-13（whIL-13）及变异型人白细胞介素-13（mhIL-13）与增强型绿色荧光蛋白（EGFP）融和蛋白真核表达载体，分析其在COS-7细胞中的表达和亚细胞定位。方法：以RT-PCR方法扩增whIL-13、mhIL-13全长编码基因，构建EGFP-whIL-13、EGFP-mhIL-13融和蛋白真核表达载体，转染COS-7细胞，以激光扫描共聚焦显微镜观察融合蛋白的表达及其在细胞内的分布情况。结果：两种融和蛋白表达载体均构建正确，将其转染COS-7细胞后，在阳性克隆胞浆内均可见明亮的绿色荧光，胞核空虚。结论：成功构建EGFP-whIL-13、EGFP-mhIL-13融和蛋白表达载体，并在COS-7细胞中得到表达，表达的两种融和蛋白细胞内分布特征没有区别，均位于胞浆内。     

SIGIRR-EGFP真核表达载体构建及在H292细胞中的亚细胞定位研究

目的 通过增强型绿色荧光蛋向示踪技术,观察SIGIRR(single Ig IL,1R-related molecule)在人气道上皮细胞株H292中的分布特点及对上皮细胞天然免疫功能的影响.方法 构建SIGIRR-EGFP融和蛋白的真核表达载体,运用脂质体转染的方法转染人气道上皮细胞株H292,再利用激光共聚焦显微镜对其进行亚细胞定位研究.经LPS刺激后,ELISA检测转染前 后上皮细胞TNF-α分泌水平的差异.结果 构建的融和蛋白表达载体SIGIRR-EGFP经EooR Ⅰ和BamH Ⅰ双酶切后,电泳显 示其条带大小为4.7 kh和1.23 kb左右,经测序证实SIGIRR的序列与GenBank公布的人cDNA序列完全一致.激光共聚焦显示pEGFP-N1空载体转染表达的绿色荧光蛋白在H292细胞中均匀分布,而重组载体SIGIRR-ECFP表达的融和蛋白在H292细胞核周(膜)和细胞膜边缘上有连续分布现象.经LPS刺激后,pEGFP-N1转染的细胞和未转染细胞TNF-α水平无显著性差异(P＞0.05),而SIGIRR-EGFP转染细胞与pEGFP-N1转染细胞相比,显著降低了TNF-α的产生(P＜0.01).结论 成功构建了SI-GIRR-EGFP融和蛋白的真核表达载体,并利用绿色荧光蛋白标记的方法显示了SIGIRR分子在H292细胞中细胞膜分布.过表达的SIGIRR降低了上皮细胞IPS诱导的炎症因子TNF-α产生.     

IDO-EGFP表达载体的构建及其在人软骨细胞中的表达

目的 克隆人吲哚胺双加氧酶(IDO)基因并构建IDO与增强型绿色荧光蛋白(EGFP)融合蛋白哺乳动物细胞表达载体。方法 利用RT-PCR方法从人白细胞克隆IDO基因并构建IDO-EGFP融合蛋白表达载体。通过细胞核转染仪将表达载体转人人软骨细胞进行瞬时表达，以共聚焦显微镜对表达的绿色荧光进行分析。结果 从活化的人白细胞中克隆到IDO基因编码区全长，并构建了IDO-EFFP融合蛋白表达载体。以该表达载体转染原代人软骨细胞，表达的融合蛋白较均匀地分布于整个细胞。结论 成功构建了IDO-EGFP哺乳动物细胞表达载体，为进一步研究IDO奠定了基础。     

CTLA4—lg融合蛋白基因的表达及其生物学功能的初步研究

获得ＣＴＬＡ４全长基因并在真核表达系统中表达。方法通过ＲＴ－ＰＣＲ方法，从ＭＴ２细胞系克隆ＣＴ－ＬＡ４全长基因；经直物重叠和半巢式ＰＣＲ改造，获得含抑瘤素Ｍ信号肽的ＣＴＬＡ４胞外段ＤＮＡ，然后克隆至真核表达载体ｐＩｇ，转染ＣＯＳ和ＣＨＯ－Ｋ细胞表达。结论真核表达体系表达了有生物学活性的ＣＴＬＡ４－Ｉｇ。     

PD-L2剪切异构体与EGFP融合蛋白的表达及其亚细胞定位研究

目的　探讨PD L2的剪切异构体在哺乳动物细胞的表达和亚细胞定位。方法　以RT PCR方法克隆人PD L2基因的常规剪切体和新型剪切异构体的cDNA ,构建其与EGFP融合的表达载体 ,分别转染K5 6 2细胞进行表达 ,经抗PD L2抗体染色后以流式细胞仪和激光共聚焦显微镜分析融合蛋白的表达及其亚细胞定位。结果　从活化的人白细胞中克隆到常规剪切体PD L2Ⅰ和新型剪切异构体PD L2Ⅱ的cDNA ,后者删除了编码胞外区Ig C结构域的外显子 3。进而构建了PD L2Ⅰ EGFP和PD L2Ⅱ EGFP融合蛋白表达载体 ,分别转染K5 6 2细胞。流式细胞仪分析显示 ,转染前者的细胞中既可检测到EGFP的表达又可在细胞膜上检测到PD L2表达 ;而转染后者的细胞中只能检测到EGFP的表达 ,在其细胞膜上不能检测到PD L2表达。共聚焦显微镜观察显示 ,PD L2Ⅰ EGFP主要分布于细胞膜表面 ,PD L2Ⅱ EGFP则主要分布于细胞内。结论　常规剪切体PD L2Ⅰ能正确定位于细胞膜表面 ,而新型剪切异构体PD L2Ⅱ则位于细胞内 ,不能运输至细胞膜 ,提示不同PD L2剪切异构体可能与其功能的调变有关     

HLA-A*0201与EGFP融合蛋白表达载体的构建及其在K562细胞的表达和定位

目的:构建增强型绿色荧光蛋白(EGFP)与HLA-A^*0201(A^*0201)融合蛋白哺乳动物细胞表达载体,分析其在K562细胞中的表达和亚细胞定位。方法:以RT-PCR方法克隆A^*0201cDNA,构建A^*0201-EGFP融合蛋白表达载体,转染K562细胞,以流式细胞仪和激光共聚焦显微镜分析融合蛋白的表达及其亚细胞定位。结果:从两个HLA-A2阳性供者外周血细胞中克隆到A^*0201cDNA编码区全长序列。通过PCR方法在起始位点前加入Kozak序列并删除终止密码,成功构建A^*0201-EGFP融合蛋白表达载体。以该质粒转染K562细胞,5h后A^*0201和EGFP的表达百分率分别为25.12±2.26、27.37±3.59,24h后表达水平无明显提高。表达的融合蛋白主要分布于细胞膜上,胞内分布较少。相反,转染空载体的细胞不表达A^*0201分子,仅表达EGFP,且其在细胞内呈弥散样分布。结论:成功构建A^*0201-EGFP融合蛋白表达载体,并在K562细胞中得到表达,表达产物主要分布于细胞膜表面,提示表达该融合蛋白的K562细胞是潜在的人工抗原提呈细胞。     

银屑病患者外周血单个核细胞中CTLA4 mRNA及蛋白的表达

目的：了解细胞毒性T淋巴细胞相关抗原4（CTLA4、CD152）mRNA及蛋白在银屑病患者外周血单个核细胞（PBMC）中的表达情况。方法：利用金葡菌肠毒素B（SEB）刺激PBMC体外增殖，采用原位杂交和ABC免疫组化方法检测寻常型现患者PBMC中CTLA4的表达。结果：银屑病患者PBMC中CTLA4 mRNA及蛋白的表达明显弱于正常人，其中进行期更弱于静止期。结论 CTLA4在银屑病患者PBMC中的表达缺陷提示CTLA4可能在银屑病发病中起一定作用。     

CTLA4-Ig在树突状细胞中的表达及效应研究

目的 获得CTLA4-Ig转基因修饰的DC细胞,分析表达产物CTLA4-Ig对T细胞活化功能的影响。方法 采用脂质体转染方法将CTLA4-Ig表达载体转入DC细胞,通过ELISA法鉴定转染DC细胞48和72h培养上清液及稳定表达的培养上清液,分离Balb/c小鼠和C57BL/10J小鼠淋巴细胞为反应细胞和刺激细胞,观察CTLA4-Ig对同种细胞混合培养反应的影响。结果 将鼠CTLA4-Ig表达载体转入DC细胞,获得瞬时表达及稳定表达,CTLA4-Ig可抑制单向混合淋巴细胞反应,且效应亦呈剂量依赖性。结论 鼠CTLA4-Ig表达产物对同种细胞刺激的增殖反应有抑制作用,其抑制作用随表达载体转染细胞培养上清液的增加而增强。同时获得了稳定表达CTLA4-Ig融合蛋白的CTLA4-Ig转基因修饰的DC细胞,为以后的工作奠定了基础。     

CTLA—4及其在T细胞活化中的作用

细胞毒性Ｔ淋巴细胞相关分子－４和ＣＤ２８的结构相似，在转录水平和蛋白 亚细胞运输水平对其表达进行调控，和Ｂ７－１，Ｂ７－２的亲和力极高，主要与Ｂ７－１分子形成受体／配体对，相互作用可以抑制Ｔ细胞的增殖，活化，是机体维持淋巴细胞稳态平衡的关键环节。     

Ovine dendritic cells transduced with an adenoviral CTLA4eEGFP fusion protein construct induce hyporesponsiveness to allostimulation

CTLA4 (CD152) is a transmembrane molecule expressed on activated T cells and functions as a negative regulator of T cell activation upon binding to the costimulatory molecules CD80/86. In this study, CTLA4eEGFP constructs were engineered by cloning the extracellular domains of ovine and human CTLA4 (CTLA4e) 'in frame' with the enhanced green fluorescent protein (EGFP). Recombinant adenoviral vectors were generated by incorporation of the CTLA4eEGFP sequence into the adenoviral genome using homologous recombination in Esherichia coli. The functional activity of the adenoviral vectors was shown by the secretion of the CTLA4eEGFP upon infection of ovine fibroblasts and the binding of the fusion protein to the target ovine and human dendritic cells expressing CD80/86 receptors by flow cytometry. The EGFP tag facilitated molecular size determinations and quantification of the secreted ovine CTLA4 fusion protein by immunoprecipitation and enzyme-linked immunosorbent assay (ELISA), respectively, using anti-GFP mAbs. Ovine dendritic cells obtained from pseudoafferent lymphatic cannulation of sheep were characterized based on high major histocompatibility complex (MHC) class II expression and cross-reactivity with monoclonal antibodies to the human dendritic cell markers, CD83 and CMRF-56. In addition, ovine dendritic cells (DC) were transfected with the adenoviral CTLA4eEGFP and when used as stimulators in a mixed lymphocyte reaction showed a reduced capacity to induce allogeneic lymphocyte proliferation. This study verifies that the ovine CTLA4eEGFP fusion protein functions similarly to its human homologue and that DC modified with adenoviral CTLA4-EGFP may provide an effective therapeutic approach in targeting alloreactive T cells to prolong allograft acceptance in a preclinical ovine model of renal transplantation.     

T细胞衔接活化因子-绿色荧光蛋白真核表达质粒的构建及其在Jurkat细胞的定位

目的:构建增强型绿色荧光蛋白(EGFP)与T细胞衔接活化因子(Linker for activated ofT cells,LAT)融合蛋白的真核表达载体,观测LAT-EGFP在Jurkat细胞中的定位表达.方法:利用RT-PCR技术提取并扩增LAT除去终止密码子外的全部序列,克隆到真核表达载体PEGFP-N3,酶切鉴定并测序.瞬时转染到Jurkat细胞中进行表达,荧光共聚焦显微镜观察LAT-EGFP在Jurkat细胞中的表达及细胞定位.提取转染后细胞总RNA,通过RT-PCR的方法检测LAT-EGFP在转录水平的表达.利用Western blot法进一步鉴定融合蛋白的表达.结果:重组载体经酶切鉴定,切出片段长度在750 bp左右与插入序列长度相符,并进一步进行测序鉴定证实连接完全正确.共聚焦显微镜观察表达的LAT-EGFP融合蛋白定位在细胞膜上,并呈点簇状聚集状态.RT-PCR扩增证实了LAT和EGFP的融合蛋白在Jurkat细胞中在转录水平的表达,Western blot分析进一步证明了LAT和EGFP融合蛋白构建成功,并在蛋白水平上有明显的融合表达.结论:成功构建真核表达载体LAT-EGFP,且融合蛋白LAT-EGFP与野生型LAT在Jurkat细胞中的定位一致,具有功能表达效应,这为后续准确研究具有棕榈酰化位点的跨膜接头蛋白的信号转导作用提供了一种良好的研究载体和方法.     

硫氧还蛋白和氧化/还原因子的融合荧光蛋白载体的构建及在293T细胞中的分布

目的构建硫氧还蛋白和氧化/还原因子的融合荧光蛋白真核表达载体,并在293T细胞中得到表达和定位。方法以RT-PCR方法从PC12细胞中克隆氧化/还原因子(APE/ref-1)的cDNA,然后亚克隆构建APE/ref-1-GFP融合真核表达载体。以PCR方法将质粒pQE30-TRX上的硫氧还蛋白cDNA亚克隆到pDsred1-1质粒上,然后将硫氧还蛋白-DsRed融合基因序列亚克隆到pCMV5质粒上,构建硫氧还蛋白-DsRed融合真核表达载体.通过磷酸钙转染293T细胞,以荧光显微镜分析融合蛋白的表达及其亚细胞定位。结果成功构建了硫氧还蛋白-DsRed和APE/ref-1-GFP融合表达载体,并在293T细胞中得到表达,APE/ref-1-GFP融合蛋白定位在293T细胞核内;硫氧还蛋白-DsRed融合蛋白定位在293T细胞质和细胞核内。结论为进一步研究硫氧还蛋白和APE/ref-1之间的动态相互作用奠定基础。     

Local gene therapy with CTLA4-immunoglobulin fusion protein in experimental allergic encephalomyelitis

It has been reported previously that the induction phase of experimental allergic encephalomyelitis (EAE) is highly sensitive to systemic blockade of stimulation via MHC class II molecules and co-stimulation via the CD28 : CD80/CD86 pathways. In contrast, the effector phases of EAE were relatively unaffected by similar treatments using MHC class II antigen (Ag)-specific mAb and cytotoxic T lymphocyte antigen (CTLA)4-Ig fusion proteins in some studies. This has been attributed to different sensitivities of effector cell function or the poor penetrance of inhibitory proteins into the central nervous system (CNS). To examine this question further, MHC class II Ag-specific mAb and CTLA4-Ig were delivered directly into the CNS following EAE induction, and both were found to inhibit disease. While it was found that systemic administration of mouse CTLA4-Ig could also inhibit the progression of effector immune responses when administered shortly before or during clinical disease, these were significantly more active when delivered directly into the CNS, which probably involved an action on both CD28 ligands, CD80 and CD86. Although mouse CTLA4-human Ig was therapeutically less efficient than mouse CTLA4-mouse Ig protein, probably due to the enhanced immunogenicity and lower functional activity, gene delivery of CTLA4-human Ig into the CNS using a non-replicating adenoviral vector was more effective than a single injection of CTLA4-human Ig protein. Gene delivery significantly ameliorated the development of EAE, without necessarily inhibiting unrelated peripheral immune responsiveness. Local gene delivery of CTLA4-Ig may thus be an important target for immunotherapy of human autoimmune conditions such as multiple sclerosis.     

CTLA4Fcε, a novel soluble fusion protein that binds B7 molecules and the IgE receptors,and reduces human in vitro soluble CD23 production and lymphocyte proliferation

Immunoglobulin E‐mediated allergy and certain autoimmune diseases are characterized by the presence of a T helper type 2 (Th2) immune response and allergen‐specific or self‐reactive IgE. Soluble CD23 (sCD23) is a B‐cell factor that fosters IgE class‐switching and synthesis, suggesting that sCD23 may be a therapeutic target for these pathologies. We produced a recombinant protein, CTLA4Fcε, by fusing the ectodomain of the immunoregulatory molecule cytotoxic T‐lymphocyte antigen 4 (CTLA‐4) with a fragment of the IgE H‐chain constant region. In SDS–PAGE/inmunoblot analyses, CTLA4Fcε appeared as a 70 000 MW polypeptide that forms homodimers. Flow cytometry showed that CTLA4Fcε binds to IgE receptors FcεRI and FcεRII/CD23, as well as to CTLA‐4 counter‐receptors CD80 and CD86. Binding of CTLA4Fcε to FcεRII/CD23 appeared stronger than that of IgE. Since the cells used to study CD23 binding express CD80 and CD86, simultaneous binding of CTLA4Fcε to CD23 and CD80/CD86 seems to occur and would explain this difference. As measured by a human CD23‐specific ELISA, CTLA4Fcε – but not IgE – induced a concentration‐dependent reduction of sCD23 in culture supernatants of RPMI‐8866 cells. Our results suggest that the simultaneous binding of CTLA4Fc? to CD23‐CD80/CD86 may cause the formation of multi‐molecular complexes that are either internalized or pose a steric hindrance to enzymatic proteolysis, so blocking sCD23 generation. CTLA4Fcε caused a concentration‐dependent reduction of lymphocyte proliferation in human peripheral blood mononuclear cell samples stimulated in vitro with concanavalin A. The ability to bind IgE receptors on effector cells, to regulate the production of sCD23 and to inhibit lymphocyte proliferation suggests that CTLA4Fc? has immunomodulatory properties on human Th2 responses.