慢病毒Lenti-CXCR4-siRNA载体的构建

目的构建介导CXCR4 RNA干扰的Lenti-CXCR4-siRNA慢病毒载体。方法将人工合成的CXCR4 siRNA经PCR扩增聚合后与线化的载体GV115连接,XhoI酶切及测序鉴定该表达质粒pLenti-CXCR4-siRNA,按Lenti-X Bicis-tronic Expression System操作手册构建Lenti-CXCR4-siRNA慢病毒,纯化后测定其滴度。结果凝胶电泳显示PCR扩增聚合产物大小正确(约60 bp)。表达质粒pLenti-CXCR4-siRNA可被XhoI内切酶线化。碱基测序证实碱基序列与设计序列一致。重组Lenti-CXCR4-siRNA慢病毒的包装细胞293T可见绿色荧光,纯化后测定其滴度,病毒滴度为2×109TU/ml。结论成功构建了高滴度的重组Lenti-CXCR4-siRNA慢病毒。     

大鼠心肌素慢病毒RNA干扰载体的构建及其对血管平滑肌细胞分化的影响

目的: 构建大鼠心肌素(myocardin)慢病毒RNA干扰(RNAi)重组质粒,分析该RNAi质粒的干扰效果及其对血管平滑肌细胞(VSMCs)分化的影响。方法: 设计并合成3对针对大鼠myocardin的shRNA片段,退火后将双链oligo-DNA克隆入慢病毒质粒载体pGCSIL- GFP获得重组干扰质粒pGCSIL- GFP-shMyocd。以pEGFP-N1 / X124G表达载体构建含Flag标签的myocardin表达质粒pEGFP-N1- Myocd。将重组干扰质粒和过表达质粒共转染293T细胞,Western blotting分析Flag标签蛋白的表达,筛选出干扰效率最好的干扰质粒并大量扩增。干扰质粒转染大鼠主动脉VSMCs,RT-PCR和Western blotting检测myocardin及分化标志物SM22α的表达。结果: 成功构建大鼠myocardin的慢病毒干扰质粒pGCSIL- GFP-shMyocd和过表达质粒pEGFP-N1-Myocd。上述2种质粒共转染293T细胞后,1号干扰质粒转染组Flag标签蛋白表达下降最显著。将1号质粒进行大包装,获得滴度为1×10¹² TU/L的慢病毒颗粒,该病毒转染VSMCs后,myocardin表达明显下调并伴随分化标志物SM22α表达的显著下降。结论: 成功构建大鼠myocardin慢病毒重组干扰质粒pGCSIL- GFP-shMyocd;抑制基因myocardin表达后伴随VSMCs分化的表达下降,提示myocardin在VSMCs分化过程中的重要性。pGCSIL- GFP-shMyocd重组质粒的成功构建为后续研究特定病理条件下(如动脉粥样硬化)VSMCs表型转变的分子机制奠定了基础。     

组织转谷氨酰胺酶基因RNA干扰慢病毒载体的构建及其对肝星状细胞的影响

目的 构建组织转谷氨酰胺酶(tTG)RNA干扰(RNAi)慢病毒载体,研究其对肝星状细胞(HSC)的影响.方法 设计、合成tTG基因RNAi有效靶序列,与慢病毒载体系统进行连接、转染,获得表达tTG基因的RNAi慢病毒载体质粒(Lenti-siRNA-tTG);将大鼠活化HSC分成阴性对照组(CON)、siRNA-GFP对照组(GFP)和siRNA-tTG组(nTG).应用real-time PCR、Western blot和MTT法检测Lenti-siRNA-tTG感染后HSC中tTG、α-平滑肌肌动蛋白(α-SMA)和Ⅰ型胶原(collagen-1)的mRNA和蛋白表达情况以及HSC的增殖情况.结果 成功构建siRNA-tTG慢病毒载体;Lenti-siRNA-tTG感染后,HSC中tTG和collagen-1的mRNA表达水平降低(P<0.05),HSC中tTG、lysine和collagen-1的蛋白表达水平下降(P<0.01),HSC的增殖能力降低(P<0.05).结论 Lenti-siRNA-tTG能通过抑制HSC中tTG基因的表达而抑制HSC的增殖,并降低HSC中collagen-1合成和交联的形成,具有潜在的抗纤维化形成的功能.     

慢病毒介导MAT2A及2B双重小干扰RNA对肝癌的抑制作用

目的 观察慢病毒载体携带的针对MAT2A和MAT2B基因双重小干扰RNA(dual siRNA)对肝癌的抑制作用.方法 分别构建靶向MAT2A、MAT2B基因的siRNA质粒,酶切、连接,构建同时针对MAT2A和MAT2B基因的慢病毒载体siMAT2A/2B,感染肝癌HepG2细胞,逆转录-聚合酶链反应(RT-PCR)测定MAT2A和MAT2B mRNA水平,细胞计数;流式细胞仪测定细胞凋亡,测定作用前后肝癌细胞内S-腺苷甲硫氨酸(SAMe)的水平.结果 成功构建慢病毒载体携带的针对MAT2A和MAT2B基因双重小干扰RNA,LV-siMAT2A/2B同时抑制肝癌MAT2A和MAT2B基因表达分别达到89.5%和97.8%,肝癌HepG2细胞生长抑制率大于50%,促进细胞凋亡,提高肝癌细胞内SAMe的水平上升了2倍.结论 同时抑制肝癌内MAT2A、MAT2B基因的表达可以抑制肝癌的生长.     

慢病毒对大鼠骨髓间充质干细胞生物学特性的影响

目的 探讨慢病毒对大鼠骨髓间充质干细胞(rMSCs)生物学特性的影响.方法 将含有绿色荧光蛋白基因的慢病毒感染第3代rMSCs.观察感染的rMSCs的形态学;感染的rMSCs与FITC标记的抗大鼠CD29抗体、PE标记的抗大鼠CD90抗体及APC标记的抗大鼠CIM5抗体孵育后,立即检测细胞表面CD29、CD90、CD45的表达水平;感染的rMSCs在成骨诱导培养基中培养21 d时,观察骨细胞的形成情况;感染的rMSCs在成脂肪诱导培养基中培养14 d时,观察脂肪细胞的形成情况;感染的rMSCs培养1、2、3、4、5、6、7、8 d时测定细胞活力;感染的rMSCs在琼脂培养基中培养21 d时,观察细胞克隆的形成情况;将感染的rMSCs接种于BALB/c-nu/nu裸鼠背部,观察接种后42 d内接种部位肿瘤的形成情况.结果 感染的rMSCs的形态学无改变,表达CD29+ CD90+ CD45-,具有形成骨细胞和脂肪细胞的能力,细胞活力无明显改变,无细胞克隆形成,接种裸鼠后接种部位未见肿瘤形成.结论 慢病毒对大鼠骨髓间充质干细胞生物学特性无影响.     

Lentiviral RNAi-induced downregulation of adenosine kinase in human mesenchymal stem cell grafts: a novel perspective for seizure control

Cell therapies based on focal delivery of the inhibitory neuromodulator adenosine were previously shown to provide potent seizure suppression in animal models of epilepsy. However, hitherto used therapeutic cells were derived from rodents and thus not suitable for clinical applications. Autologous patient-derived adenosine-releasing cell implants would constitute a major therapeutic advance to avoid both xenotransplantation and immunosuppression. Here we describe a novel approach based on lentiviral RNAi mediated downregulation of adenosine kinase (ADK), the major adenosine-removing enzyme, in human mesenchymal stem cells (hMSCs), which would be compatible with autologous cell grafting in patients. Following lentiviral transduction of hMSCs with anti-ADK miRNA expression cassettes we demonstrate up to 80% downregulation of ADK and a concentration of 8.5 ng adenosine per ml of medium after incubating 10(5) cells for 8 h. hMSCs with a knockdown of ADK or cells expressing a scrambled control sequence were transplanted into hippocampi of mice 1 week prior to the intraamygdaloid injection of kainic acid (KA). While mice with control implants expressing a scrambled miRNA sequence or sham treated control animals were characterized by KA-induced status epilepticus and subsequent CA3 neuronal cell loss, animals with therapeutic ADK knockdown implants displayed a 35% reduction in seizure duration and 65% reduction in CA3 neuronal cell loss, when analyzed 24 h after KA-injection. We conclude that lentiviral expression of anti-ADK miRNA constitutes a versatile tool to generate therapeutically effective adenosine releasing hMSCs, thus representing a model system to generate patient identical autologous adult stem cell grafts.     

VP_(22)修饰的CD基因工程化神经干细胞治疗大鼠C6脑胶质瘤体外实验研究

目的 探讨病毒蛋白VP_(22)在胞嘧啶脱氨酶(cytosine deaminase,CD)基因工程化神经干细胞治疗大鼠C6胶质瘤中的作用.方法 质粒pAdTrack-CMV-CD中PCR获取CD片段,克隆到慢病毒(lentivirus)质粒pHIV-EGFP和pHIV-VP_(22)-EGFP载体上,获得重组质粒pHIV-CD-EGFP和pHIV-VP_(22)-CD-EGFP,采用酶切和PCR技术进行鉴定.病毒包装采用三质粒系统共同转染293T细胞.CD基因的表达采用逆转录-聚合酶链式反应(RT-PCR)方法鉴定.Lentivirus-EGFP、lentivirus-CD-EGFP、lentivirus-VP_(22)-EGFP和lentivirus-VP_(22)-CD-EGFP四种慢病毒感染经体外原代培养、扩增的SD大鼠胎脑神经干细胞(Nerual stem cells,NSCs),体外与C6细胞按1:1比例共培养,并加入终浓度100 mg/L的5-氟胞嘧啶(5-FC)培养3 d后,MTT比色法测定细胞存活率.结果 酶切和PCR证实,重组的慢病毒中含有CD基因.慢病毒lentivirus-EGFP、lentivirus-CD-EGFP、lentivirus-VP_(22)-EGFP和lentivirus-VP_(22)-CD-EGFP分别感染NSCs后与C6细胞共培养,在5-FC作用下,其细胞存活率分别为(95.57±4.83)%,(49.96±7.19)%,(94.25±4.32)%和(28.06±6.26)%.统计学处理,转染lentivirus-CD-EGFP和lentivirus-VP_(22)-CD-EGFP组的细胞存活率明显低于其相应对照组lentivirus-EGFP和lentivirus-VP_(22)-EGFP(P<0.01);其中转染lentivirus-VP_(22)-EGFP组的细胞存活率又明显低于lentivirus-EGFP组(P<0.01).结论 VP_(22)能够在体外增强CD基因修饰的NSCs抗C6胶质瘤疗效.     

Survivin shRNA重组慢病毒构建及对A549细胞增殖的影响

背景与目的 Survivin是凋亡抑制蛋白(inhibitor of apoptosis protein,IAP)家族的成员,在多种肿瘤组织中高度表达而在终末分化细胞中极少表达,因此可以作为癌症治疗的理想靶点.本研究旨在通过构建Survivin基因shRNA的慢病毒质粒并干扰肺癌细胞A549中Survivin的表达,分析其对细胞增殖的影响.方法 设计Survivin干扰靶序列,构建重组质粒;将pLL3.7-Survivin转染293T细胞后利用Hela细胞检测病毒的滴度并感染A549细胞,应用RTPCR和Western blot检测干扰效果;MTT与流式细胞术分析其对细胞增殖的影响.结果 本研究成功构建了重组质粒;重组质粒可抑制A549细胞中Survivin基因的表达;细胞受阻于G2/M期.结论 本研究构建的重组质粒可抑制Survivin基因的表达并影响细胞的增殖,其为研究RNAi介导的肺癌基因治疗打下基础.     

Vaccine-induced enhancement of viral infections

Examples of vaccine-induced enhancement of susceptibility to virus infection or of aberrant viral pathogenesis have been documented for infections by members of different virus families. Several mechanisms, many of which still are poorly understood, are at the basis of this phenomenon. Vaccine development for lentivirus infections in general, and for HIV/AIDS in particular, has been little successful. Certain experimental lentiviral vaccines even proved to be counterproductive: they rendered vaccinated subjects more susceptible to infection rather than protecting them. For vaccine-induced enhanced susceptibility to infection with certain viruses like feline coronavirus, Dengue virus, and feline immunodeficiency virus, it has been shown that antibody-dependent enhancement (ADE) plays an important role. Other mechanisms may, either in the absence of or in combination with ADE, be involved. Consequently, vaccine-induced enhancement has been a major stumble block in the development of certain flavi-, corona-, paramyxo-, and lentivirus vaccines. Also recent failures in the development of a vaccine against HIV may at least in part be attributed to induction of enhanced susceptibility to infection. There may well be a delicate balance between the induction of protective immunity on the one hand and the induction of enhanced susceptibility on the other. The present paper reviews the currently known mechanisms of vaccine-induced enhancement of susceptibility to virus infection or of aberrant viral pathogenesis.     

携带DREAM基因shRNA的慢病毒载体的构建及其对坐骨神经缩窄损伤大鼠的镇痛作用

目的：构建含下游调控元件的拮抗分子（downstream regulatory element antagonistic modulator,DREAM）基因有效短发夹RNA(shRNA)的慢病毒载体, 利用RNA干扰技术抑制DREAM基因表达,开展对神经病理性疼痛基因治疗的实验研究。方法：将靶向大鼠DREAM基因的shRNA重组到慢病毒穿梭质粒中,将重组质粒pKCSHR-puro/GFP-DREAM和慢病毒包装系统共转染293T细胞包装成慢病毒,收集病毒上清并进行载体病毒滴度的测定。将纯种健康清洁级成年雄性SD大鼠36只随机分为6组: 正常对照组(N)、假手术组(S),根据干预手段的不同将大鼠坐骨神经缩窄损伤（chronic constriction injury of sciatic nerve, CCI）模型组分为4组:CCI(C0)组, CCI疼痛模型建立后不给任何干预措施,生理盐水对照（C1）组,空白载体对照（C2）组,LV-shRNADREAM慢病毒载体治疗（C3）组。该3组大鼠于CCI后第7天分别于蛛网膜下腔注射生理盐水、空白载体、LV-shRNADREAM慢病毒载体。观察各组大鼠术后3,7,10,14,21 d的疼痛行为学的改变。实验结束取腰段脊髓荧光显微镜检测绿色荧光蛋白(GFP)的表达,Realtime-PCR测定DREAM基因的mRNA 含量、Western印迹测定DREAM 蛋白含量。结果：测序分析证实载体构建成功,成功进行慢病毒包装,得到病毒液滴度为1.0×108 IFU/mL慢病毒载体。鞘内注射LV-shRNADREAM慢病毒载体后, CCI大鼠热痛阈和机械痛阈的异常明显得到改善（P<0.01）, 腰段脊髓神经细胞DREAM基因mRNA和 DREAM蛋白的表达均显著降低（P<0.01）。结论：成功构建了携带大鼠DREAM基因有效shRNA的慢病毒载体,慢病毒携带的短发夹干扰ＲＮＡ能干扰脊髓中DREAM的表达,为神经病理性疼痛的治疗提供了实验基础。