Glypican3 N端融合基因构建及鉴定

目的 构建人磷酯酰肌醇蛋白聚糖3(glypican3,GPC3)N端融合基因.方法 采用RT-PCR技术,从人肝癌细胞株HepG2 mRNA中扩增GPC3 N端基因片段,经双酶切后,T4DNA连接酶将此片段定向连接至质粒pcDNA3.1,并转化大肠埃希菌DH5a,增菌培养后提取质粒并PCR扩增、酶切鉴定及序列测定.结果 GPC3 N端基因片段正确插入质粒pcDNA3.1,片段大小及序列正确.结论 成功构建重组质粒pcDNA3.1-GPC3N.     

干细胞因子基因cDNA克隆及其在造血干细胞中的表达

目的:克隆人干细胞因子基因cDNA,构建真核表达载体并转导脐带血造血干细胞,观察干细胞因子在造血干细胞中的表达,从而为脐血造血干细胞扩增及移植奠定实验基础。方法:实验于2005-09/12在承德医学院基础医学研究所和湖南师范大学医学院寄生虫病研究室完成。①实验材料:健康胎儿脐带由承德医学院附属医院提供,产妇均签署知情同意书;pcDNA3.1.大肠杆菌E.coliDH5α由本室保存;pUCm-T vector (promega公司);BamHⅠ,XbaⅠ(New England BioLabs公司):②实验方法:无菌收集胎儿脐带,胶原酶 胰蛋白酶 乙二胺四乙酸联合消化,分离培养人脐带内皮细胞。从上述含脐带内皮细胞的培养液中分离提取干细胞因子mRNA,用反转录-聚合酶链反应扩增干细胞因子cDNA.纯化的PCR产物与载体pUCm-T加入连接反应体系,构建及克隆pUCm-T/SCF质粒,其与pcDNA3.1分别进行BamHⅠ、XbaⅠ双酶切反应,产物经琼脂糖凝胶电泳后回收干细胞因子cDNA和pcDNA3.1片段,构建真核表达型载体pcDNA3.1/SCF。以密度梯度法 免疫磁珠法分离收集人脐血CD34~ 造血干细胞.导入pcDNA3.1/SCF,设立未转导对照组。③实验评估:转导后1～7 d检测两组细胞上清液中干细胞因子水平的表达。结果:①人于细胞因子基因cDNA克隆:扩增的人干细胞因子基因cDNA理论上应为690 bp,实际PCR产物经琼脂糖凝胶电泳后,紫外线下可见-预期大小的条带,证明干细胞因子mRNA提取成功,反转录合成的cDNA完整。②分泌型真核表达质粒pcDNA3.1/SCF的构建:BamHⅠ和XbaⅠ双酶切后电泳可见690 bp的插入片段,与干细胞因子基因序列相同,表明分泌型真核表达质粒pcDNA3.1/SCF构建成功。③脐血造血干细胞培养上清中的干细胞因子水平:培养第1～7天.转导pcDNA3.1/SCF的脐血造血干细胞上清中的干细胞因子表达水平均明显高于未转导对照组(P<0.01)。结论:成功克隆人干细胞因子基因cDNA,并构建了重组质粒pcDNA3.1/SCF,该质粒转导脐血造血干细胞后.能在短期内有效表达。     

弓形虫致密颗粒蛋白GRA4真核表达质粒的构建

目的构建弓形虫致密颗粒蛋白GRA4的真核表达重组质粒。方法设计合成GRA4引物,运用PCR方法扩增其基因片段,经克隆至pMD18-T载体后,亚克隆至真核表达质粒pcDNA3.1(-)而构建重组表达质粒pcDNA3.1-GRA4。结果PCR扩增GRA4基因序列正确,构建的重组表达质粒pcDNA3.1-GRA4经PCR、EcoRⅠ/HindⅢ双酶切和测序鉴定正确。结论成功获得真核表达重组质粒pcDNA3.1-GRA4,为进一步研究弓形虫疫苗的免疫保护性奠定基础。     

脆性X综合征致病基因FMR1一个新型隐匿外显子发现及其鉴定

目的 分析脆性X智力障碍1基因(FMR1基因)可变剪接表达类型.方法 采用克隆-测序技术,从RNA途径分析人FMR1基因的可变剪接表达.结果 构建健康人外周血cDNA 53个T克隆,测序结果显示4个T克隆均有140 bp大小的插入片段(NG_007529:21452-21591),为FMR1内含子9的一部分,生物信息学比对显示该片段上下游具有4个经典的剪接信号,可能为新的隐匿外显子.巢式PCR显示健康人多种组织cDNA中普遍存在该片段.杂种小基因剪接试验显示该片段可通过可变剪接,与上游的外显子9和下游的外显子10同时出现在体外培养真核细胞的成熟mRNA中.结论 该研究发现人FMR1基因的新型隐匿外显子,丰富了人FMR1基因可变剪接的内容,也为进一步研究可变剪接与脆性X综合征发病机制之间的关系和脆性X智力障碍1蛋白的功能奠定了基础.     

人肝细胞生长因子与肝再生增强因子融合基因真核表达质粒的构建及鉴定

目的:构建人肝细胞生长因子(hHGF)与肝再生增强因子(hALR)融合基因的真核表达质粒并进行鉴定,为促肝细胞再生研究奠定实验基础.方法:首先分别以重组质粒pUC18-hHGF和Puc18-hALR为模板,进行PCR扩增,获得hHGF和hALR的基因序列,然后利用重叠延伸PCR方法将获得的基因序列通过一个连接序列进行连接,构建融合基因hHGF/hALR.最后将融合基因定向插入到真核表达质粒pcDNA3.1的Nhe I和Xba I酶切住点之间,构建重组真核表达质粒pcDNA3.1-hHGF/hALR,并进行双酶切及测序鉴定.结果:hHGF和hALR的PCR扩增产物电泳后分别观察到2.2 kb和0.4kb的单一DNA条带,与理论值相符.重叠延伸PCR扩增后的融合基因产物电泳后观察到2.6kb的单一DNA条带,与预期值一致.重组真核表达质粒pcDNA3.1-hHGF/hALR经双酶切,电泳后观察到2.6 kb和5.4kb的两条DNA条带,与预期值相符,测序鉴定结果表明序列正确.结论:成功构建了hHGF与hALR融合基因的真核表达质粒,为促肝细胞再生研究奠定实验基础.     

人PIF1全长基因及其截短体真核表达载体的构建及鉴定

目的构建人PIF1基因5端、3端及全长基因的真核表达载体。方法从pCR2.1-TOPO-PIF1原始质粒中,采用PCR方法扩增目的基因PIF1,PIF1N及PIF1C,将目的基因和目的载体pcDNA3.1(-)分别酶切;纯化酶切产物后定向连接,并将其转化大肠杆菌DH5α,对生长出的克隆行特异限制性内切酶酶切鉴定,鉴定为阳性的克隆送样测序。结果凝胶成像结果显示重组基因pcDNA3.1(-)-PIF1,pcDNA3.1(-)-PIF1N及pcDNA3.1(-)-PIF1C酶切后条带大小分别为1 926,540,1 428bp。结论成功构建hPIF1基因5端、3端及全长基因表达载体,分别为pcDNA3.1(-)-PIF1N,pcDNA3.1(-)-PIF1C及pcDNA3.1(-)-PIF1。     

Myc/his-TDP-43融合蛋白对tau外显子10可变剪接的影响

目的:构建带myc/his标签的pcDNA3.1/TDP-43及其截断体质粒,探讨myc/his-TDP-43融合蛋白对tau外显子10可变剪接的影响。方法:采用PCR法扩增TDP-43基因及其各截断体,将扩增产物和载体pcDNA3.1双酶切后回收,连接载体和目的片段,获得重组质粒。在HEK-293FT细胞中转染pcDNA3.1/TDP-43·myc·his及其截断体质粒,Western印迹法检测相关蛋白的表达。TDP-43或siTDP-43和tau迷你基因SI9/SI10共转,RT-PCR检测TDP-43对tau外显子10可变剪接的影响。结果:成功构建了pcDNA3.1/TDP-43·myc·his全长及各截断体质粒,并在HEK-293FT细胞中检测到其蛋白表达。Myc/his-TDP-43融合蛋白可呈剂量依赖性促进4R-tau的表达(P0.05或0.01)。结论:Myc/his-TDP-43融合蛋白可促进4R-tau的表达,携带myc/his标签不影响TDP-43对tau外显子10可变剪接的促进作用,为后续研究奠定了基础。     

新型内源性磁共振报告基因——小鼠铁蛋白基因的构建

目的 应用pcDNA3.1(-)质粒载体系统构建携带小鼠铁蛋白重链全基因质粒,并探讨铁蛋白基因作为一种新型内源性磁共振分子影像报告基因的可行性和优越性.方法 从来源于小鼠肌肉的mRNA,应用一对含有限制性内切酶Not Ⅰ和BamH Ⅰ酶切位点的引物进行逆转录聚合酶链反应(RT-PCR),扩增出铁蛋白重链全基因(Fth)片断.通过限制性内切酶Not Ⅰ和BamH Ⅰ酶切和T4连接酶的作用,将铁蛋白重链全基因插入到载体pcDNA3.1(-)中,构建铁蛋白重链全基因质粒pcDNA3.1(-)-Fth.结果 质粒pcDNA3.1(-)-Fth成功构建,符合酶切和测序鉴定结果.结论 初步构建的小鼠铁蛋白重链质粒,为进一步探讨铁蛋白基因作为一种新型内源性磁共振分子影像报告基因在细胞示综和基因显像中的应用奠定了基础.     

弓形体RH株抗原基因SAG1的扩增克隆及鉴定

目的：体外扩增弓形体主要表面抗原SAG1基因,构建pcDNA3-SAG1真核表达质粒,为研制弓形体疫苗奠定基础。方法：采用PCR技术,自行设计一对寡核酸引物（P1,P2）,从弓形体RH株基因组DNA中特异扩增出编码SAG1抗原的基因片段,扩增的目的片段经纯化后用EcoR1和HindⅢ双酶切后,克隆到真核表达质粒pcDNA3中,转化入大肠杆菌TG1,用氨苄青霉素和PCR初筛,将PCR扩增阳性的重组子分别用Sac1单酶切、EcoR1和HindⅢ双酶切鉴定,结果成功地构建真核型表达质粒pcDNA3-SAG1,从而为进一步SAG1重组抗原的体外表达创造有利条件。结果：从RH株基因组DNA中特异扩增出编码SAG1的全基因序列,扩增目的基因片段大小与预期长度（1025bp),相符;将分离、纯化的目的基因片段SAG1任入pcDNA3质粒HindⅢt和EcoR1位点,构建重组质粒pcDNA3-SAG1。结论：成功构建重组质粒pcDNA3-SAG1。     

乙型肝炎病毒X基因真核表达载体的构建

目的构建含有乙型肝炎病毒(HBV)X基因的真核表达载体,并对其表达进行鉴定。方法用聚合酶链反应(PCR)方法扩增X基因序列,对pcDNA6(+)载体及X基因PCR产物双酶切并转化大肠杆菌DH5α,筛选阳性克隆,并对其进行双酶切和测序鉴定,构建HBV X基因真核表达载体pcDNA6(+)-HBx。以多聚乙烯酰胺(PEI)法将其转染到HepG2细胞,Western Blot鉴定目的蛋白。结果 pcDNA6-HBx酶切后,琼脂糖电泳可见到HBx基因片段,经序列测定其含有完整的X基因片段;Western Blot结果显示pcDNA6(+)-HBx能在HepG2细胞中表达X蛋白。结论成功构建了真核表达载体pcDNA6(+)-HBx,并能在HepG2细胞中表达X蛋白,为进一步研究HBV X基因与慢性乙型肝炎及肝癌的关系提供便利条件。     

Anticancer drugs affect the alternative splicing of Bcl-x and other human apoptotic genes

Inducing an apoptotic response is the goal of most current chemotherapeutic interventions against cancer. However, little is known about the effect of chemotherapeutic agents on the alternative splicing of apoptotic genes. Here, we have tested 20 of the mainstream anticancer drugs for their ability to influence the production of Bcl-x splice isoforms. We find that many drugs shift splicing toward the proapoptotic Bcl-x(S) splice variant in 293 cells. The drugs modulate splicing decisions most likely through signaling events because the splicing switch is not compromised by inhibiting de novo protein synthesis or the activity of caspases. Several drugs also shift Bcl-x splicing in cancer cell lines (MCF-7, HeLa, PC-3, PA-1, and SKOV-3), but the set of active drugs varies between cell lines. We also examined the effect of anticancer agents on the alternative splicing of 95 other human apoptotic genes in different cell lines. Almost every drug can alter a subset of alternative splicing events in each cell line. Although drugs of the same class often influence the alternative splicing of the same units in individual cell lines, these units differ considerably between cell lines, indicating cell line-specific differences in the pathways that control splicing.     

Point mutations regarded as missense mutations cause splicing defects in the factor XI gene

See also Duga S, Asselta R. Mutations in disguise. This issue, pp 1973–6. Summary. Background: Point mutations within exons are frequently defined as missense mutations. In the factor (F)XI gene, three point mutations, c.616C>T in exon 7, c.1060G>A in exon 10 and c.1693G>A in exon 14 were reported as missense mutations P188S, G336R and E547K, respectively, according to their exonic positions. Surprisingly, expression of the three mutations in cells yielded substantially higher FXI antigen levels than was expected from the plasma of patients bearing these mutations. Objectives: To test the possibility that the three mutations, albeit their positions within exons, cause splicing defects. Methods and results: Platelet mRNA analysis of a heterozygous patient revealed that the c.1693A mutation caused aberrant splicing. Platelet mRNA of a second compound heterozygote for c.616T and c.1060A mutations was undetectable suggesting its degradation. Cells transfected with a c.616T minigene favored production of an aberrantly spliced mRNA that skips exon 7. Cells transfected with a mutated minigene spanning exons 8–10 exhibited a significant decrease in the amount of normally spliced mRNA. In silico analysis revealed that the three mutations are located within sequences of exonic splicing enhancers (ESEs) that bind special proteins and are potentially important for correct splicing. Compensatory mutations created near the natural mutations corrected the putative function of ESEs thereby restoring normal splicing of exons 7 and 10. Conclusions: The present findings define a new mechanism of mutations in F11 and underscore the need to perform expression studies and mRNA analysis of point mutations before stating that they are missense mutations.     

A novel transgenic mouse model for immunological evaluation of carcinoembryonic antigen-based DNA minigene vaccines

A lack of relevant animal models has hampered preclinical screening and critical evaluation of the efficacy of human vaccines in vivo. Carcinoembryonic antigen-A2Kb (CEA-A2Kb) double transgenic mice provide a biologically relevant model for preclinical screening and critical evaluation of human CEA vaccine efficacy in vivo, particularly because such animals are peripherally tolerant of CEA. We established the utility of this model by demonstrating that an oral DNA minigene vaccine induces effective HLA-A2-restricted, CEA-specific antitumor CTL responses. This finding is supported by three lines of evidence: (a). an effective HLA-A2-restricted, CEA(691)-specific CTL response; (b). specific in vitro killing of CEA-A2Kb transduced MC-38 colon carcinoma cells; and (c). protective immunity induced in vaccinated mice against challenges of these tumor cells. Importantly, peripheral T cell tolerance against CEA in CEA-A2Kb double transgenic mice was broken by the CEA(691) (IMIGVLVGV) minigene vaccine. In conclusion, CEA-A2Kb double transgenic mice were demonstrated to be good candidates for in vivo testing of human CEA-based vaccines. This result suggests a potential for these vaccines in future human vaccine development. The feasibility of using nonmutated self-antigens as targets for therapeutic vaccinations was indicated, provided that such antigens are presented in an immunogenic context; that is, as a DNA minigene in a bacterial carrier system.     

A novel DHPLC-based procedure for the analysis of COL1A1 and COL1A2 mutations in osteogenesis imperfecta

Approximately 90% of patients with osteogenesis imperfecta (OI) exhibit dominant COL1A1 or COL1A2 mutations; however, molecular analysis is difficult because these genes span 51 and 52 exons, respectively. We devised a PCR-denaturing high-performance liquid chromatography (DHPLC) procedure to analyze the COL1A1 or COL1A2 coding regions and validated it using 130 DNA samples from individuals without OI, 25 DNA samples from two cells to investigate the procedure's potential for preimplantation diagnosis, and DNA samples from 10 patients with OI. Three novel intronic variants in vitro were expressed using a minigene assay to assess their effects on splicing. The procedure is rapid, inexpensive, and reproducible. Analysis of samples from individuals without OI revealed six novel and some known polymorphisms useful for linkage diagnosis because of high heterozygosity. Analysis of two-cell samples confirmed the known genotype in 24 of 25 experiments; DNA failed to amplify in only one case. No incidence of allele dropout was recorded. DHPLC revealed six novel mutations, three of which were intronic, in all patients with OI, and these results were confirmed by means of COL1A1 and COL1A2 direct sequencing. Expression of intronic mutations demonstrated that variant 804 + 2_804 + 3delTG in intron 11 disrupts normal splicing, thereby leading to formation of two alternative products. Variants c.3046-4_3046-5dupCT (COL1A1) and c.891 + 77A>T (COL1A2) did not affect splicing. The described DHPLC protocol combined with the minigene assay may contribute to molecular diagnosis in OI. Moreover, this protocol will aid in counseling about prenatal and preimplantation diagnosis.     

Prevention of the dystrophic phenotype in dystrophin/utrophin-deficient muscle following adenovirus-mediated transfer of a utrophin minigene

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder caused by the lack of a subsarcolemmal protein, dystrophin. We have previously shown that the dystrophin-related protein, utrophin is able to compensate for the lack of dystrophin in the mdx mouse, the mouse model for DMD. Here, we explore whether utrophin delivered to the limb muscle of dystrophin/utrophin-deficient double knockout (dko) neonatal mice can protect the muscle from subsequent dystrophic damage. Utrophin delivery may avoid the potential problems of an immune response associated with the delivery of dystrophin to a previously dystrophin-deficient host. Dko muscle (tibialis anterior) was injected with a first generation recombinant adenovirus containing a utrophin minigene. Up to 95% of the fibres continued expressing the minigene 30 days after injection. Expression of utrophin caused a marked reduction from 80% centrally nucleated fibres (CNFs) in the uninjected dko TA to 12% in the injected dko TA. Within the region of the TA expressing the utrophin minigene, a significant decrease in the prevelance of necrosis was noted. These results demonstrate that the utrophin minigene delivered using an adenoviral vector is able to afford protection to the dystrophin/utrophin-deficient muscle of the dko mouse. Gene Therapy (2000) 7, 201-204.     

卵巢癌细胞ERCC1基因VIII外显子剪接变异及功能研究

目的　确认卵巢癌细胞ERCC1基因VIII外显子剪接变异的存在 ,探讨该剪接变异对ERCC1基因表达的作用及其对卵巢癌细胞对铂类药物耐药性的影响。方法　采用Northern杂交及RNA酶保护分析确认人卵巢癌细胞内ERCC1基因调控区在RNA水平存在剪接变异。分别构建野生型及缺失VIII外显子的ERCC1表达载体 ,转染中国仓鼠卵巢 4 3 3B细胞 ,采用Westernblot检测ERCC1表达水平研究该剪接变异对ERCC1基因表达水平的影响 ,采用MTT和细胞克隆形成实验研究该剪接变异细胞对铂类药物耐药性的影响。结果　卵巢癌细胞ERCC1基因VIII外显子存在剪接变异。Westernblot结果显示该剪接变异不显著影响ERCC1表达水平 ,但CHO 4 3 3B细胞MTT及细胞克隆形成实验表明 ,该剪接变异显著影响细胞对顺铂的耐药性。结论　本研究首次证明人卵巢癌细胞、组织ERCC1基因VIII外显子存在剪接变异 ,该变异不显著影响ERCC1基因的绝对表达水平 ,但影响细胞对顺铂的耐药性