p53途径的双荧光素酶报告系统在食品致癌物筛选中的应用研究

目的应用p53途径的双荧光素酶报告系统筛选食品中的致癌物。方法双荧光素酶试验中,采用萤火虫荧光素酶检测食品中常见的致突变性/致癌性物质的p53基因表达水平,同时以海肾荧光素酶作为内对照。结果文献报道有致突变性/致癌性的8个样品中有7个双荧光素酶试验结果为阳性,而且阳性剂量低于大多数传统毒理试验,阳性样品的荧光素酶活性有随着处理剂量的增加而增高的趋势;缺乏致突变性/致癌性文献的隐色结晶紫的荧光素酶活性仅略有增加。结论 p53途径的双荧光素酶报告系统可能是一种比较理想的高通量食品致癌物筛选系统。     

生物发光技术在活体成像检测中的应用

生物发光体内成像检测技术已广泛应用于许多动物实验中,其优势在于可对特定的细胞和分子行为进行非侵入性的体内评价和连续动态研究,这些细胞和分子往往是药物作用或基因治疗的靶点。该技术有效减少了所需实验动物的数量,也减小了因个体差异引起的误差,改进了数据点的质量。     

HCV脱氧核酶在荧光素酶表达细胞中活性的初步观察

脱氧核酶 (ｄｅｏｘｙｒｉｂｏｚｙｍｅ ,ＤＲｚ)是具有生物催化活性的小分子酶性ＤＮＡ(ｃａｔａｌｙｔｉｃＤＮＡ) ,能定点剪切ＲＮＡ分子 ,其活性中心系所谓 10～ 2 3基序 (ｍｏｔｉｆ)。本研究对丙型肝炎病毒 (ＨＣＶ)靶向性ＤＲｚ、硫代修饰的ＤＲｚ (ｐｈｏｓｐｈｏｒｏｔｈｉｏａｔｅｄｅｏｘｙｒｉｂｏｚｙｍｅｓ,ＴＤＲｚ)和突变硫代ＤＲｚ(ｍｕｔａｎｔｐｈｏｓｐｈｏｒｏｔｈｉｏａｔｅＤＲｚ,ＭＤＲｚ)在靶基因调控性荧光素酶表达细胞中的活性进行了初步观察。ＤＲｚ、ＴＤＲｚ、ＭＤＲｚ由上海Ｓａｎｇｏｎ公司合成。ＨｅｐＧ2…     

P53对涎腺腺样囊性癌细胞端粒酶活性的抑制作用

目的为了探讨P53基因对腺样囊性癌细胞端粒酶活性的抑制作用及机制。方法构建携带人野生型P53基因的腺病毒表达载体，以脂质体法瞬时转染腺样囊性癌SACC-83细胞，RT-PCR检测转染细胞P53基因mRNA的表达，TRAP-PCR-ELISA法检测转染细胞端粒酶活性的改变。并将P53基因与含有hTERT启动子核心调控区的荧光素酶报告基因pGL2—630共转染SACC-83细胞，测定转染细胞荧光素酶报告基因活性。结果1．瞬时转染含人野生型P53基因的重组腺病毒表达载体p△E1-P53于腺样囊性癌SACC-83细胞后，其P53基因mRNA的表达明显增强；2．基因转染后，SACC-83细胞内源性端粒酶活性显著降低。3．P53基因与含有hTERT启动子核心调控区的荧光素酶报告基因pGL2-630共转染SACC-83细胞后，其荧光素酶活性显著下降。结论外源性表达P53基因可以降低腺样囊性癌细胞SACC-83细胞端粒酶活性，并可能通过抑制端粒酶hTERT基因启动子的转录活性实现。     

丙型肝炎病毒与荧光素酶融合基因细胞模型的初步建立

Objective　To establish HCV cell culture model which is easy to measure. Methods　Controllable retroviral vector with fusion gene of hepatitis C virus (HCV) cDNA and luciferase (luc) reporter gene was constructed by molecular cloning technique, the transfection of this retroviral vector in a human hepatic carcinoma cell (HHCC) line was performed by lipofectAMINE and then luciferase activity in the cellular lysate was measured by scintillation counter. Results　 ① Fusion gene of the HCV 5′ NCR-C region and luciferase reporter gene identified by restriction endonuclease cleavage have been cloned into pBPSTR1 vector. ② The luciferase activity could maintain up to 20 days at least, and could be increased by puromycin treatment and regulated by tetracycline. Conclusion　A cell model for expression of HCV C-E1 and luciferase genes was established for gene therapy studies against HCV C-E1 sequences.     

Effect of structural domain Ⅱ of HCV 5' noncoding region on its translation initiation activity

Objective To examine the role of domain Ⅱ of hepatitis C virus(HCV) 5'noncoding region (5'NCR) in its translation initiation activity. Methods The fragment of HCV 5' NCR with deletions of 5'-proximal 118 nucleotides were amplified with PCR, then was used to substitute for the full length HCV 5'NCR of plasmid pCMVNCRIuc, a firefly luciferase(Flue) eukaryotic expression plasmid regulated by HCV 5' NCR, to generate recombinant plasmid pCN1-d3, pCMVNCRIuc, pCN1-d2 (modified pCMVNCRluc with deletions of HCV 5' NCR nt1-43) and pCN1-d3 were transfected into HepG2 cells with liposome transfection protocol, respectively, and the relative luciferase activity was measured to analyze the regulatory effect of the truncated 5'NCR on Fluc gene expression. Meanwhile the Fluc mRNA levels were detected by RT-PCR. Results The recombinant plasmid was successfully constructed. The Fluc mRNA levels of the 3 plasmids were not significantly different(P 0.05), and there were also no significant difference between the relative luciferase activity of plasmids pCN1-d2 and pCMVNCRluc(P 0.05). However, that of pCN1-d3 was decreased significantly(P < 0.01, compared with pCN1-d2 or pCMVNCRluc). Conclusion Structural domain Ⅱ of HCV 5' NCR plays an important role in itstranslation initiation activity.     

虫荧光素酶的生物发光分析

萤火虫荧光素酶(firefly luciferase)发光系统是生物发光中研究得最透彻、深入的一种,也是生物发光分析在医学中应用得最广泛的一种。早在1885年Dubois就报     

Effect of structural domain Ⅱ of HCV 5' noncoding region on its translation initiation activity

Objective To examine the role of domain Ⅱ of hepatitis C virus(HCV) 5'noncoding region (5'NCR) in its translation initiation activity. Methods The fragment of HCV 5' NCR with deletions of 5'-proximal 118 nucleotides were amplified with PCR, then was used to substitute for the full length HCV 5'NCR of plasmid pCMVNCRIuc, a firefly luciferase(Flue) eukaryotic expression plasmid regulated by HCV 5' NCR, to generate recombinant plasmid pCN1-d3, pCMVNCRIuc, pCN1-d2 (modified pCMVNCRluc with deletions of HCV 5' NCR nt1-43) and pCN1-d3 were transfected into HepG2 cells with liposome transfection protocol, respectively, and the relative luciferase activity was measured to analyze the regulatory effect of the truncated 5'NCR on Fluc gene expression. Meanwhile the Fluc mRNA levels were detected by RT-PCR. Results The recombinant plasmid was successfully constructed. The Fluc mRNA levels of the 3 plasmids were not significantly different(P 0.05), and there were also no significant difference between the relative luciferase activity of plasmids pCN1-d2 and pCMVNCRluc(P 0.05). However, that of pCN1-d3 was decreased significantly(P < 0.01, compared with pCN1-d2 or pCMVNCRluc). Conclusion Structural domain Ⅱ of HCV 5' NCR plays an important role in itstranslation initiation activity.     

miR-1290与RASAL2基因靶向关系的探索

目的通过构建RASAL2 3′-非翻译区(3′-UTR)双荧光素酶报告载体,探索RASAL2与非编码核糖核酸(ncRNA)miR-1290的靶向调控情况。方法借助在线数据库Targetscan预测miR-1290与RASAL2结合位点;利用聚合酶链反应(PCR)技术扩增RASAL2基因3′-UTR序列,并以GV272为载体将其连接,分别构建野生型GV272-RASAL2-wt 3′-UTR和突变型GV272-RASAL2-mut 3′-UTR荧光素酶报告基因重组质粒;并将miR-1290及相应阴性对照分别与这两种重组质粒共转染到293T细胞中,通过检测各组荧光素酶活性,探索miR-1290与RASAL2基因的结合情况。结果酶切和测序数据表明:野生型GV272-RASAL2-wt 3′-UTR及突变型GV272-RASAL2-mut 3′-UTR双荧光素酶报告载体构建成功;相较于miR-1290与突变型GV272-RASAL2-mut 3′-UTR共转染组,miR-1290与野生型GV272-RASAL2-wt 3′-UTR共转染组的荧光素酶活性无明显变化(P＞0.05)。结论成功构建了RASAL2 3′-UTR的双荧光素酶报告基因载体,但miR-1290不能与RASAL2结合,不能抑制其表达。     

NNMT基因启动子双荧光素酶报告系统的构建及其与SND1靶向关系的验证

目的:构建尼克酰胺-N-甲基转移酶（NNMT）启动子区的双荧光素酶报告质粒并检测其活性,从而验证SND1蛋白对NNMT基因的调控作用。方法:根据NNMT基因启动子区上、下游-1 500至+200区间的序列设计引物,并以HepG2细胞提取的RNA逆转录得到cDNA为模板进行PCR扩增,得到的NNMT启动子区片段经酶切后连接到双荧光素报告载体GLuc-ONTM启动子报告克隆中,得到Gluc-NNMT 启动子重组质粒,分别与pLVX-IRES-Puro-Flag-SND1质粒和pLVX-IRES-Puro-vector质粒共同转染HeLa细胞,并检测启动子活性。然后用免疫共沉淀的方法验证NNMT蛋白是否与SND1蛋白之间存在相互作用。结果:重组质粒构建成功。双荧光素酶活性实验显示,共转染Gluc-NNMT启动子重组质粒和pLVX-IRES-Puro-Flag-SND1过表达质粒的实验组与对照组相比,NNMT启动子区活性明显增强。结合免疫共沉淀实验结果,证明NNMT与SND1存在相互作用。结论:成功构建了NNMT启动子双荧光素酶报告质粒,SND1对NNMT启动子活性有增强作用,SND1与NNMT蛋白之间存在相互作用。