ASM真核表达载体的构建与鉴定

目的:构建含有酸性鞘磷脂酶(Acid sphingomyelinase,ASM)融合基因片段的质粒,并在真核细胞中表达、鉴定。方法:由人淋巴结cDNA文库中扩增基因片段,将ASM基因插入真核表达载体pEGFP-N1中,获得融合基因构建真核表达载体ASM-pEGFP-N1。以其瞬时转染Hela细胞,应用免疫印迹与流式细胞术检测融合蛋白与绿色荧光蛋白的表达。结果:正确获得ASM融合基因,DNA序列分析表明所构建的含ASM融合基因的质粒与设计相同,融合蛋白与绿色荧光蛋白均正确表达。结论:成功构建了含有ASM融合基因的真核表达载体,并在真核细胞中正确表达,为进一步研究肿瘤与ASM表达之间的关系奠定了基础。

Construction and Preliminary Identification of Eukaryotic Expression Vector of Cryptosporidium parvum miR-2980

[Objective] This study aimed to construct and preliminarily identify the eu- karyotic expression vector of Cryptosporidium parvum miR-2980. [Method] The cp-miR- 2980 precursor was amplified from C. parvum genomic DNA and cloned into pMD18- T vector. The amplified precursor was then subcloned into pVAX I vector and identi- fied with restriction endonuclease digestion and sequencing. The recombinant plasmid pVAX-miR2980 was transfected into HCT-8 cells. Total RNA was extracted and the expression of cp-miR-2980 was evaluated by RT-PCR detection. [Result] The results showed that the recombinant eukaryotic expression vector pVAX-miR2980 was suc- cessfully constructed, which can express cp-miR-2980 in HCT-8 cell. [Conclusion] This study laid the foundation for further exploring the biological function of cp-miR-2980.

Construction and Characterization of an Antisense RNA Eukaryotic Expression Vector for Survivin

Objective: To inhibit specifically survivin expression and block its function in leukemia cells, an antisense RNA expression plasmid for survivin was constructed and transfected into a leukemia cell line.Methods: A cDNA fragment of survivin obtained by RT-PCR was inserted into a plasmid vector named pcDNA3 in the reverse direction. Antisense RNA of survivin was confirmed by restriction enzyme digestion and DNA sequencing. The recombinant plasmid was transfected into the cell line HL-60 by electroporation. The effect of survivin antisense RNA on survivin mRNA expression in transfected cells was examined by RT-PCR.Results: The correct construction of the recombinant plasmid has been shown by restriction enzyme digestion and DNA sequencing. As compared to controls, the level of survivin mRNA expression in transfected cells decreased significantly.Conclusion: An antisense RNA vector for survivin has been successfully constructed and may be useful as a specific inhibitor in leukemia cells. Thus, antisense therapy on the basis of survivin can be further explored in leukemia. Key words leukemia - survivin - antisense RNA This project was supported by a grant from National Key Basis Research Program of China (No. CB 513109) and the National Natural Sciences Foundation of China (No. 39970693).

Construction of Eukaryotic Expression Vector for Pig Ghrelin Gene

[Objective] This study aimed to investigate the functions of transgenic growth related gene in pig growth. [Method] A pair of primers containing Nhe I and Hind Ⅲ restriction sites were designed by referring to the pig Ghrelin mRNA sequence published in Genbank. Total RNA was extracted from the small intestine tissue of 13/17 Robertson translocation heterozygous pig, and then was purified and used as the template in later RT-PCR reaction to amplify the full-length pig Ghrelin gene. The correct pig Ghrelin gene fragment was cloned into the pMD19-T simple vector for sequencing analysis. The obtained full-length cDNA of pig Ghrelin gene fragment was digested with both Nhe I and Hind Ⅲ, and then was linked into the eukaryotic expression vector pEGFP-N1 to obtain the recombinant plasmid pEGFPGhrelin. The recombinant plasmid was transected into the fibroblast cells to detect the fluorescence labeled gene expression. [Result] The nucleotide sequence extracted from 13/17 Robertson translocation heterozygous pig was the same as expected; and the eukaryotic expression vector pEGFP-Ghrelin was successfully constructed. [Conclusion] The eukaryotic expression vector constructed in this study can be further used in research on transgenic pigs, but also lays foundation for research on the regulatory mechanism of Ghrelin gene.

Construction of RNAi Vector Which Resist Cucumber Mosaic Virus and Transformation of Tobacco

[Objective] Aimed to construct RNAi vector resistant to cucumber mosaic virus and transferred this vector into tobacco. [Method] RT-PCR method was used to amplify cucumber mosaic virus NS04 and process RNA2 gene sequen of tomato isolates. The analysis results of phylogenetic tree demonstrated that the sequence in RNA2 encoded CMV-2a had 98.0% and 96.5% homology with nucleotide and amino acid of DQ412731 isolate of Zhejiang,China. The replicase fragment in CMV RAN2 gene was taken as target sequence to construct pBi35SCR2 eukaryotic expression vector,then the expression vector was identified. Through agrobacterium-mediated method,the expression vector was transferred into tabacco and PCR method was used to check the transfer. The PCR results demonstrated that the experiment had successfully construct eukaryotic expression vector of pBi35SCR2 and the expression vector was successfully transferred into tabacco. [Conclusion] The obtained transgenic tobacco could be used as challenge test material in following experiment and provided foundation for studying processing tomato resist cucumber mosaic virus.

Expression and Purification of Enterovirus Type 71 Polyprotein P1 using Pichia pastoris system

Enterovirus type 71（EV71） causes severe hand-foot-and-mouth disease （HFMD） resulting in hundreds of deaths of children every year; However, currently, there is no effective treatment for EV71. In this study, the EV71 poly-protein （EV71-P1 protein） gene was processed and cloned into the eukaryotic expression vector pPIC9k and then expressed in Pichia pastoris strain GSll5. The EV71 P1 protein with a molecular weight of 100 kD was produced and secreted into the medium. The soluble EV71 P1 protein was purified by column chromatography with a recovery efficiency of 70%. The result of the immunological analysis showed that the EV71 P1 protein had excellent immunogenicity and could stimulate the production of EV71-VP1 IgG antibody in injected rabbits. We suggest that EV71-P1 protein is an ideal candidate for an EV71 vaccine to prevent EV71 infection.

Effects of HMGB1 Expression Suppressed by siRNA on Cell Cycle and Proliferation of Human Cervical Cancer Cell Line HeLa

OBJECTIVE In this study, RNA interference was used to evaluate the effects of HMGB1 expression on cell cycle and proliferation of the human cervical cancer cell line HeLa.METHODS We had previously constructed and screened effective eukaryotic expression vectors carrying PGCsi3.0-1/ HMGB1 siRNA and PGCsi3.0-3/HMGB1 siRNA, then the vectors were transfected into HeLa cells. The expression of HMGB1 before and after transfection in HeLa cells were detected by RT-PCR and Western blot. The cell viability and proliferating activity was tested by Trypan blue dye test and MTT, and the cell cycle was determined bv flow cvtometry.RESULTS The introduction of PGCsi3.0-1/HMGB1 siRNA and PGCsi3.0-3/HMGB1 siRNA inhibited the expression of HMGB1 mRNA and protein efficiently and specifically, there was a significant difference between the siRNA groups and the control groups （P 〈 0.05）. The proliferation speed of PGCsi3.0-1 group and PGC si3.0-3 group were obviously slower than those of PGCsi3.0- Neg group and non-transfected group. Flow cytometry showed that the content of DNA in G2 phase in PGCsi3.0-1 group and PGCsi3.0-3 group were obviously more than those in PGCsi3.0- Neg group and non-transfected group, but the content in S phase was less （P 〈 0.01）. The progression of cell cycle was arrested from G2 to S phase.CONCLUSION PGCsi3.0-1/HMGB1 siRNA and PGCsi3.0-3 /HMGB1 siRNA could specially suppress the expression of HMGB1 gene, inhibit the proliferation speed of HeLa cells effectively, and arrest the progression of cell cycle from G2 to S phase. RNAi provides a new approach to the bio-therapy of cervical cancer.

Construction of eukaryotic expression vector carrying human TSLC1 gene and its expression in HepG2 cells

Objective： To construct the eukaryotic expression vector for human TSLC1 gene, and to express TSLC1 in HepG2 cells for investigating its effect on HepG2 cell growth. Methods： Full length of TSLC1 cDNA was amplified from RNA of normal human liver by RT-PCR, and cloned into pCI-neo expression vector. The recombinant plasmid pCI-TSLC1 was identified with restriction enzyme and sequenced, and then was stably transfected into HepG2 cells with lipofectamine 2000. The positive clones were examined by western-blotting and immunofluorescence, cell growth was analyzed with MTT assay. Results： The eukaryotic expression vector pCI-TSLC1 was successfully constructed and the stable cell line highly expressing TSLC1 protein was obtained. The growth of TSLCl-transfected cells was significantly suppressed in vitro. Conclusion： The HepG2 stable cell line could highly express TSLC1 protein, which provided a basis for further exploring the roles of TSLC1 in hepatocellular carcinoma.

Cxcl16 Interact With SARS-CoV N Protein In and Out Cell

Our study investigated the host cell protein which can interact with SARS-CoV N protein, and explored the functional connections. The eukaryotic expression vectors pEGFP-N1/SARS-CoVN and pdsRed2-N1/ CXCL16 were constructed and used to co-transfect HEK293FT cells by the calcium phosphate method. The HIS-tagged fusion protein SARS-CoVN-GFP was then built and purified for the binding assay in vitro. The co-localization of SARS-CoVN and CXCL16 in the cytoplasm of HEK293FT cells was also shown using confocal laser scanning microscopy. It is suggested that their interaction might be through direct combination. Under a fluorescence microscope, it was observed that the purified fusion protein SARS-CoVN-GFP was attached to the cell membrane of CXCL16-transfected cells, indicating that SARS-CoVN and CXCL16 can be mutually combined.

Decreasing Pin1 suppressed the properties of migratory and invasive in colorectal carcinoma SW620 cells

Objective:The aim of our study was to investigate the effect of Pin1 on the expression of MMP-2 and MMP-9 in human colorectal carcinoma SW620 cells. Methods: We constructed a eukaryotic expression vector of RNA interfering (shRNA) for Pin1 gene (pGenesil-1-Pin1), and then observed its expression in SW620 cells by Western blotting. The cells motility were tested by wound healing assay and Boyden chamber assay. The protein levels and activity of MMP-2 and MMP-9 were tested by Western blotting and Gelatin zymography in SW620 cells after transfected with pGenesil-1-PIN1. Results: pGenesil-1-PIN1 was successfully constructed, which was confirmed by sequencing. Silencing the Pin1 by RNAi significantly decreased the cells motility from 96.4±3.9 per field (×10 objective) to 52.7±4.4 per field (P<0.05, Student's t-test) for SW620 cells transfected with pGenesil-1-PIN1 (SW620/p-shRNA) in Boyden chamber assay, and reduced the MMP-2 and MMP-9 expressions and activity in SW620 cells. The protein relative levels of MMP-2 were 0.32±0.04 for SW620/p-shRNA, and 0.76±0.03 for SW620/p-Con; MMP-9 were 0.41±0.09 for SW620/p-shRNA, and 0.94±0.07 for SW620/p-Con (p<0.05). Conclusion: Inhibited Pin1 expression may contribute to the suppression of the invasive and metastatic capacity of colon cancer cells in vitro.

Construction of a HERG mutant L539fs/47-*558W pEGFP vector and the expression of the fusion protein in HEK293 cells

Objective： To construct a human ether-a-go-go-related gene （HERG） nonsense mutant L539fs/47-558W into the autonomously fluorescent, eukaryotic expression vector pEGFP-C2, and to verify expression of the reconstruct in human embryonic kidney-293 （HEK293） cells. Methods： The mutational fragment was subcloned into pEGFP-C2-HERG by double digestion of Sbf I, Eco91 1 and rejoining of T4 ligase. After verification, the recombinant pEGFP-C2-L539fs/47-558W and pEGFP-C2-HERG were respectively transfected into HEK293 cells for 48 h by the Lipofect method to observe the expression location of the fusion protein by laser confocal imaging scanning in vivo. pcDNA3 -L539fs/47-＊558W and pcDNA3-HERG were transfected to observe the expression location of the HERG protein by immunofluoresceoce. The mutant protein size was determined by Western blotting. Results： The about 1 kb-sized mutation region cDNA fragment from pcDNA3-L539fs/47-＊558Wand the about 7.2 kb-sized target vector fragment from pcDNA3-HERG were ligated after purification and gel recovery pEGFP-C2-L539fs/47＊-558W, approximately 8.2 kb, was demonstrated successfully been constructed under agarose gel electrophoresis and further sequencing. Laser confocal imaging showed that pEGFP-C2-HERG was mainly expressed in the membrane, whereas truncated mutant-type HERG in the pEGFP-C2 vector was partially located in the cytoplasm, the others were transported to the cell membrane in living HEK293 cells. The same as the immunofluoresceoce results after transfection of pcDNA3-HERG and pcDNA3-L539fs/47-558W. Wild-type HERG-GFP fusion protein expressed 160 and 180 kDa bands. The mutant and mutant-GFP fusion proteins were 70 and 100 kDa, respectively. Conclusion： pEGFP-C2-L539fs/47-＊558W was successfully constructed by double digestion method GFP had no effect on its protein expression and trafficking in HEK293 cells, which laid a foundation for the further study on L539fs/47-＊558W

Expression of Recombinant Protein Bovine Prion pCIp264 in COS-7 Cells and Its Detection

Bovine spongiform encephalopathy （BSE） is thought to be caused by prions initially derived from sheep scrapie, and epidemiological studies suggest that new viriant form of CJD manifest in Great Britain may be caused by BSE prions. PrP^Sc is thought to pathogenic factor of transmissible spongiform encephalopathy （TSE）, which invariably involve a post-translational modification process of PrPc encoded by the host euchromosome PrP gene during the period it converted into the pathogenic form （PrP^Sc）, PrP is nomal cellular protein which has been found in both neuronal and nonneuronal tissues. Since the crucial infectious event in protein-transmitted diseases is an induced misfolding of prion proteins （PrP^c） catalyzed by already misfolded PrP^Sc, it is of high importance that such collisions are enhanced by two-dimensional diffusion in cell membranes is of high importance compared to three-dimensional diffusion in solution. The level of PrP mRNA in brain is higher than other tissue, but purification of PrPc from rodent has been difficult. To understand the formation of PrP^Sc, it seemed useful to develop a system for produced a large quantities of PrPc since there is no nature source of PrP^c. The pCI-neo mammalian expression vector contains the neomycin phosphtransferase gene which serves as a marker for the selection of stable transfected cells with G418. COS-7 cells constitutively express simian viruse 40 （SV40） T-antigen and support replication of expression plasmids containing the SV40 origin of replication, amplifying the introduced expression cassettes, now become important routine of expression a large number of heterologous gene products. In this paper, the authors used pCI-neo vector to construct a recombnant pCIp264 （cotains mPrP, N-signalpeptide and C-GPI anchor） plasmid to express it in the COS-7 cells and meanwhile detect the expression fusion using IN-ELISA, IN-IFA and western blot, and obtain some approximative nature PrPc.