CD46 RNAi对CD59介导的T细胞信号转导的作用研究

目的构建携带针对CD46基因的pSUPER retro RNAi逆转录病毒载体,研究糖基磷脂酰肌醇(GPI)锚定蛋白CD59与CD46在介导T细胞信号转导中的相关性。方法将能转录产生靶向CD46小发夹RNA(shRNA)的寡核苷酸序列,克隆入逆转录病毒载体pSUPER retro,转化大肠杆菌JM109并转染Jurkat细胞。将Jurkat细胞分为未转染的Jurkat细胞组(Ⅰ组)、转染空质粒的Jurkat细胞组(Ⅱ组)、转染CD59干扰质粒的Jurkat细胞组(Ⅲ组)及转染CD46干扰质粒的Jurkat细胞组(Ⅳ组)。用RT-PCR、Western blot技术检测各组细胞中的CD59、CD46基因的表达水平。用噻唑蓝(MTT)比色法检测CD46与CD59联合作用对4组Jurkat细胞的增殖效应。结果重组载体经PCR及限制性内切酶酶切鉴定初步成功后送测序,结果表明序列正确,构建成功,稳定转染后,Ⅳ组细胞CD46分子的表达被成功抑制,Ⅲ组细胞CD59分子的表达被抑制。Ⅰ组和Ⅱ组细胞CD46与CD59单抗联合作用后,增殖能力明显高于Ⅲ组、Ⅳ组(P<0.05);但Ⅰ组和Ⅱ组,Ⅲ组和Ⅳ组之间无差异。结论 CD59可增强CD46对T细胞信号转导的效应。     

CD59锚定蛋白对CD55介导的T细胞信号转导的增强效应

目的:研究糖基磷脂酰肌醇(GPI)锚定蛋白CD59对CD55介导T细胞信号转导的增强效应。方法:实验分为未转染的Jurkat细胞组(Ⅰ组)、转染空质粒的Jurkat细胞组(Ⅱ组)及转染CD59干扰质粒的Jurkat细胞组(Ⅲ组)。用RT-PCR检测3组细胞中的CD59基因表达水平。用噻唑蓝(MTT)比色法、免疫印迹技术和激光共聚焦扫描显微镜分别检测CD55与CD59联合作用对3组Jurkat细胞的增殖效应,Src家族酪氨酸激酶(SrcPTK)磷酸化的水平及细胞内钙离子的变化。结果:稳定转染后,Ⅲ组细胞CD59分子的表达被成功抑制。Ⅰ组和Ⅱ组细胞CD55与CD59联合作用后增殖能力,SrcPTK磷酸化水平及钙离子浓度均明显高于Ⅲ组(P<0.05);但Ⅰ组和Ⅱ组之间无差异。结论:CD59可增强CD55对T细胞信号转导的效应。     

CD45在细胞信号转导中的调节机制

CD45是位于白细胞表面的白细胞共同抗原 (leukocytecommonantigen, L CA), 属于单链跨膜大分子糖蛋白家族,高水平地表达在淋巴细胞以及除红细胞和血小板之外的所有造血细胞上。现已证实至少有 9种异构体 (isoform), 由 4 ~6个外显子交替剪接而成。这些异构体的胞外结构各不相同,但却有相同的胞质结构 [1]。单个淋巴细胞可同时表达多个异构体, T细胞和B细胞表达的异构体则有所不同, 在T细胞各个亚群以及不同发育阶段也存在明显差异 [2]。CD45分子参与多种免疫功能, 其高度保守的胞质区具有磷酸酪氨酸酯酶(PTPase)活性, 使得其在信…     

CD59真核表达载体的构建及其对Jurkat细胞增殖的影响

目的构建pIRES-CD59融合基因真核表达载体,探讨重组CD59在Jurkat细胞增殖中的作用。方法 RT-PCR法选择性扩增编码CD59的基因片段,克隆入pIRES真核表达质粒。脂质体法将重组载体转染Jurkat细胞,通过G418筛选获得稳定表达CD59的细胞克隆,利用RT-PCR和Western blot检测细胞中CD59的表达,通过MTT法检测Jurkat细胞的增殖。结果经酶切和测序鉴定表明携带CD59基因的重组质粒构建成功,RT-PCR和Western blot结果显示转染Jurkat细胞的CD59基因高表达,MTT实验显示转染CD59重组质粒的Jurkat细胞增殖速度明显快于对照组(P<0.05)。结论 pIRES-CD59真核表达载体在转染细胞Jurkat中可高表达CD59分子,并可影响Jurkat细胞的增殖,为研究CD59的生物学作用奠定了基础。     

SH2A 基因对细胞信号转导的影响及其亚细胞定位

目的 研究Src同源域2(src homology 2，SH2)A基因在细胞信号转导中的作用并进行亚细胞定位。方法 通过RT—PCR方法扩增SH2A cDNA编码序列，构建真核重组表达载体pcDNA3．1-SH2A，利用脂质体转染肝癌Bel7402细胞、COS7细胞，检测蛋白酶C(protein kinaseC，PKC)、酪氨酸蛋白激酶(tyrosine protein kinase，TPK)、丝裂原激活蛋白激酶(mitogen activated protein kinase，MAPK)活性的改变；另构建pEGEP—SH2A，转染同前，荧光显微镜观察荧光定位。结果 测序结果显示真核重组表达载体pcDNA3．1-SH2A及pEGFP—SH2A中均含有SH2AcDNA编码序列；肝癌Bel7402细胞、COS7细胞转染pcDNA3．1-SH2A后，胞浆PKC的活性下降了40％左右，MAPK和TPK活性未见明显改变。荧光显微镜观察发现SH2A基因在细胞质中表达。结论 SH2A基因编码蛋白在PKC信号转导通路中起抑制作用；SH2A基因编码蛋白定位于细胞质。     

LAT介导GPI锚固蛋白CD59对Jurkat细胞的生物学效应研究

目的探讨在T系急性白血病的Jurkat细胞中,GPI类锚固蛋白CD59通过LAT介导的细胞增殖、活化、凋亡等相关的生物学效应,研究GPI锚固类膜蛋白分子对细胞调控的作用方式。方法分别构建LAT-EGFP、neg-EGFP融合蛋白慢病毒载体,转染Jurkat细胞,建立稳定表达株(LAT-EGFP作为实验组,neg-EGFP转染空病毒组作为对照组)。利用CD59单克隆抗体刺激实验组及对照组细胞后,通过CCK-8检测细胞的增殖活性,利用流式细胞术检测细胞凋亡状况,并通过激光共聚焦显微镜观察LAT与CD59分子在细胞中的定位表达。最后利用免疫印迹技术检测细胞内相关信号转导蛋白的表达情况。结果 CD59单抗交联刺激后,细胞增殖活性增加。实验组细胞出现明显晚期凋亡甚至坏死现象。而免疫荧光显示LAT-EGFP组细胞中LAT分子高亮聚集于脂筏区,相较于对照组细胞呈现明显的戒指环状。Western blot显示,CD59抗体交联后,ZAP70、Fyn、LCK的表达均下降且LATEGFP组蛋白表达量低于对照组。结论 GPI锚固蛋白CD59通过T细胞活化连接蛋白LAT对T细胞信号转导发挥正向调控作用,转染LAT-EGFP的Jurkat细胞处于活化状态,LAT呈戒指环状定位于脂筏。     

CD59锚定蛋白对CD3介导Jurkat细胞活化信号转导中的增强效应

目的用前期构建好的CD59pSUPER-RNAi质粒转染Jurkat细胞,探讨CD59特异性沉默前后CD59对CD3介导Jurkat细胞活化信号转导的相关作用。方法采用Lipofectamine2000转染Jurkat细胞,经G418筛选建立稳定转染细胞系,利用RT-PCR检测转染后CD59在基因水平的表达抑制效果。实验分为未转染的Jurkat细胞组(A组),转染空质粒pSUPER组(B组)和转染CD59pSUPER-RNAi质粒的Jurkat细胞组(C组),用噻唑蓝(MTT)比色法,Western blot技术和激光共聚焦扫描显微镜分别检测交联CD59单抗与固相化CD3单抗联合作用对3组Jurkat细胞的增殖效应,ZAP-70酪氨酸磷酸化的水平及细胞浆内钙离子的变化。结果重组载体转染后,经G418筛选得到稳定转染细胞系,RT-PCR结果表明转染CD59pSUPER-RNAi质粒的Jurkat细胞组CD59分子的表达受到抑制。转染干扰质粒Jurkat细胞组CD59与CD3联合作用后细胞增殖能力,ZAP-70酪氨酸磷酸化水平及钙离子浓度均明显低于未转染组和转染空质粒组(P<0.05);但未转染组和转染空质粒组之间无差异。结论 CD59对CD3介导T细胞活化信号转导有增强效应。     

锚定蛋白CD59与接头分子Cbp在T细胞上的定位及功能研究

目的 研究CD59、Src羧基末端激酶结合蛋白(Cbp)在细胞膜的定位,及其在细胞活化及增殖中的相互作用.方法 应用免疫荧光细胞化学技术,通过荧光显微镜分析系统对CD59、Cbp的定位进行了分析;Jurkat细胞转染pSUPER-siCD59重组质粒,并行RT-PCR和Western blot法检测转染细胞中CD59的表达及蛋白酪氨酸激酶癌基因家族(fyn)磷酸化水平.利用MTT比色法检测转染各组细胞的增殖效应.结果 CD59、Cbp主要分布在细胞膜上.转染pSUPER-siCD59重组质粒的Jurkat细胞中CD59表达量减少,磷酸化的fyn含量也随之减少,细胞增殖能力也低于其他各组.结论 CD59是一种膜蛋白,在细胞活化及增殖中与Cbp分子共同发挥作用.     

下调CD59 对急性T 系白血病细胞株Jurkat 凋亡相关分子的影响

目的:探讨下调CD59 对急性T 系白血病细胞株Jurkat 凋亡相关分子的影响。方法:运用RNAi 慢病毒为载体下调急性T 系白血病Jurkat 细胞株CD59 的表达;激光共聚焦观察转染效率及CD59 分子的定位;Real-time-PCR、Western blot 筛选下调效果最好的一组细胞,用其做后续的分子生物学水平的实验; Western blot 检测Bcl-2、Bax、Caspase-3、Survivin 蛋白表达量的变化;ELISA 检测各组的细胞培养上清中IL-3、TNF-α的表达。结果:激光共聚焦观察到转染各组的转染效率在90%以上,CD59 分子主要位于细胞膜;Real-time-PCR 筛选得出下调A 组的转染效果最好; Western blot 结果显示下调A 组的CD59 蛋白的表达量减少最明显,将RNAi-CD59-A 定义为RNAi-CD59 作为实验组进行后续实验;实验组能增强Bax、Caspase-3蛋白的表达(P<0.05),抑制Bcl-2、Survivin 蛋白的表达(P<0.05);ELISA 结果显示下调组IL-3 表达水平降低(P<0.05), TNF-α的表达水平升高(P<0.05)。结论:下调D59 基因表达可使急性T 系白血病细胞株Jurkat 的促凋亡分子表达增高,促增殖分子表达降低。     

下调CD59对急性T系白血病细胞株Jurkat凋亡相关分子的影响北大核心CSCD

目的:探讨下调CD59对急性T系白血病细胞株Jurkat凋亡相关分子的影响。方法:运用RNAi慢病毒为载体下调急性T系白血病Jurkat细胞株CD59的表达;激光共聚焦观察转染效率及CD59分子的定位;Real-time-PCR、Western blot筛选下调效果最好的一组细胞,用其做后续的分子生物学水平的实验;Western blot检测Bcl-2、Bax、Caspase-3、Survivin蛋白表达量的变化;ELISA检测各组的细胞培养上清中IL-3、TNF-β的表达。结果:激光共聚焦观察到转染各组的转染效率在90%以上,CD59分子主要位于细胞膜;Real-time-PCR筛选得出下调A组的转染效果最好;Western blot结果显示下调A组的CD59蛋白的表达量减少最明显,将RNAi-CD59-A定义为RNAi-CD59作为实验组进行后续实验;实验组能增强Bax、Caspase-3蛋白的表达(P<0.05),抑制Bcl-2、Survivin蛋白的表达(P<0.05);ELISA结果显示下调组IL-3表达水平降低(P<0.05),TNF-β的表达水平升高(P<0.05)。结论:下调D59基因表达可使急性T系白血病细胞株Jurkat的促凋亡分子表达增高,促增殖分子表达降低。     

A transfected human muscarinic receptor fails to substitute for the T cell antigen receptor complex in CD2-initiated signal transduction

Several T cell surface molecules can activate signal transduction pathways that lead to T cell activation. Like the T cell antigen receptor (TCR), several other molecules, including the sheep erythrocyte receptor CD2, are able to activate the phosphatidylinositol (PI) signal transduction pathway upon stimulation with appropriate agonists. However, CD2-initiated activation of this pathway is dependent on the functional expression of the TCR. Since the T cell does not express other known receptors that activate the PI pathway independent of the TCR, the specificity of the CD2 requirement for a functional TCR is not known. To evaluate the specificity of this requirement, we examined the functional capacity of CD2 to activate the PI pathway in a TCR-deficient cell which had been transfected with a heterologous receptor, the human muscarinic subtype 1 receptor (HM1). HM1 is a member of the cholinergic family of receptors and is known to activate the PI pathway. HM1 can function in the absence of the TCR in a Jurkat-derived T cell host. Here we demonstrate through calcium fluorimetry and PI metabolism assays that HM1 is unable to substitute functionally for the TCR in CD2-initiated signal transduction. These results suggest a specific functional interaction between CD2 and the TCR in CD2-mediated activation of the PI pathway in T cells.     

Impaired T cell signal transduction through CD28 in a patient with idiopathic thrombocytopenia.

We describe an infant whose peripheral blood mononuclear cells were unable to proliferate or synthesize IL-2 in response to a mitogenic combination of antibodies directed against CD2 and CD28. This peculiar defect, which has been stable to date, was attributed to an impairment in CD28-mediated T cell activation, because further comitogenic combinations containing anti-CD28 monoclonals also failed to induce normal proliferation of the patient's T cells. In contrast, proliferation after membrane stimulation (with anti-CD2, recombinant IL-2, or certain lectins) or transmembrane activation (with phorbol ester and calcium ionophore) was normal, suggesting that his lymphocytes did not have a general membrane or intracellular signalling impairment. A T cell line derived from the patient confirmed the existence of a severe defect in CD28-mediated T cell proliferation, but also showed a profound impairment in CD3-induced T cell proliferation. Other cell surface molecules like CD2 and CD25 were, in contrast, capable of transducing normal proliferation signals. As all relevant molecules were detectable by cytofluorography and immunoprecipitation, we conclude that the patient's lymphocytes had an intrinsic defect in the delivery of CD28-mediated signals which, in the absence of monocytes, also affected CD3-mediated proliferation. The study of this novel kind of immunodeficiency may help to unravel the complex interactions that take place among CD2, CD3 and CD28 during T cell activation. The presence of an idiopathic thrombocytopenia in the patient suggests the intriguing possibility of a role for CD28 in the maintenance of peripheral blood platelets levels, although alternative interpretations are not ruled out.     

Characterization of p59fyn-mediated signal transduction on T cell activation

Protein tyrosine kinase p59^fyn is associated with the TCR -CD3 complex and is suggested to play a role in T cell activation.To determine the molecular mechanism of p59^fyn-medlated signaltransduction in T cell activation, we established murine T cellhybridoma lines that expressed an elevated amount of wild-typeor mutant fyn. Clones that expressed high levels of normal p59^fynand active p59^fyn, encoded by wild-type and f-14 mutant fynrespectively, showed enhanced IL-2 production upon stimulationby anti-CD3 antibodies or natural antigen. On the other hand,clones that expressed kinase negative p59^fyn and p59^fyn withan SH2 (Src-homology 2) deletion encoded by t-1 mutant fyn showedlittle induction of IL-2 production upon stimulation. Thesedata suggest that p59^fyn is important in T cell signaling andthat the SH2 sequence plays a critical role in the reaction.Induction of tyrosine phosphorylatlon of multiple proteins uponantigenic stimulation was augmented similarly in the cells thatrespectively expressed wild-type and f-14 mutant fyn at elevatedlevels. The proteins that became highly tyrosine-phosphorylatedincluded phospholipase C (PLC-1), P95^vav, ZAP-70, the MAP kinase,CD3 and unidentified proteins of 120, 100 and 80 kDa. Tyrosinephosphorylation of the 120, 95 and 68 kDa proteins associatedwith PLC-1 was also observed in these cells upon stimulation.In contrast, only the 100 kDa protein and the MAP kinase wereincreasingly tyrosine phosphorylated in the antigen-stimulatedcells expressing t-1 fyn. These data suggest that PLC-1, PLC-1associated molecules, p95^vav, the 80 kDa protein, ZAP-70 andthe CD3 chain may be substrates of p59^fyn or of other tyrosinekJnases regulated by p59^fyn and be important in T cell signaling.     

The T cell receptor associated CD3-ϵ protein is phosphorylated upon T cell activation in the two tyrosine residues of a conserved signal transduction motif

Signal transduction through the Tcell receptor for antigen, the TcR/CD3 complex, involves phosphorylation of tyrosine residues in the CD3-? chain. Since both CD3-?and the ζ, chain contain a tyrosine-based signaling motif, we examine phosphorylation of CD3-? in human T cells. Engagement of the TcR/CD3 complex induced tyrosine phosphorylation of CD3-? in vivo. Induction of CD3-? phosphorylation followed similar kinetics to that of the ζ, chain phosphorylation. In contrast to ζ, CD3-? phosphorylation was strictly dependent upon cell surface expression of this member of the TcR/CD3 complex. Chemical and proteolytic cleavage combined with peptide-specific Western blotting established that CD3-? phosphorylation occurred in the two tyrosine residues located in the signal transduction motif in the C-terminal portion of the molecule. Taken together, these data indicated that phosphorylation of CD3-? by tyrosine protein kinases may serve to couple the TcR/CD3 complex to other effector molecules in the signaling cascade.     

埃兹蛋白参与调控的信号转导通路研究进展

埃兹蛋白（Ezrin）是细胞骨架连接蛋白（Ezrin-Radixin-Moesin,ERM）家族成员之一,主要分布于细胞皮层。Ezrin作为膜蛋白和肌动蛋白连接蛋白,在调控细胞的形态、生长、生存、黏附、增殖和迁徙等生物学功能中发挥重要作用。其作用机制复杂,涉及Rho、PKA、PKC、MAPK及细胞凋亡等多条信号传导通路。因此,研究Ezrin相关的信号转导,对认识疾病的发展及治疗具有重要意义。