Characterisation of alternative expression vectors for recombinant Bacillus Calmette-Guérin as live bacterial delivery systems

BACKGROUND Bacillus Calmette-Guérin (BCG) is considered a promising live bacterial delivery system. However, several proposals for rBCG vaccines have not progressed, mainly due to the limitations of the available expression systems. OBJECTIVES To obtain a set of mycobacterial vectors using a range of promoters with different strengths based on a standard backbone, previously shown to be stable. METHODS Mycobacterial expression vectors based on the pLA71 vector as backbone, were obtained inserting different promoters (PAN, PαAg, PHsp60, PBlaF* and PL5) and the green fluorescence protein (GFP) as reporter gene, to evaluate features such as their relative strengths, and the in vitro (inside macrophages) and in vivo stability. FINDINGS The relative fluorescence observed with the different vectors showed increasing strength of the promoters: PAN was the weakest in both Mycobacterium smegmatis and BCG and PBlaF* was higher than PHsp60 in BCG. The relative fluorescence observed in a macrophage cell line showed that PBlaF* and PHsp60 were comparable. It was not possible to obtain strains transformed with the extrachromosomal expression vector containing the PL5 in either species. MAIN CONCLUSION We have obtained a set of potentially stable mycobacterial vectors with a arrange of expression levels, to be used in the development of rBCG vaccines.

Construction and identification of ST8Sial gene over-expression vector and its effect on proliferation of human melanoma cells / 中国药理学通报

Aim To construct different over-expression vectors of ST8Sial gene and establish a cell line with stable ST8Sial over-expression , and to check the proliferation of cells with ST8Sial over-expression. Methods Polymerase chain reaction ( PCR) was used to amplify the code region of ST8Sial. The amplified ST8Sial fragment and pEGFP-Cl vector, pHBLV-CMV-MCS-3flag-EFl-ZsGreen-T2A-Puro vector were digested with restriction enzymes. The target gene fragment and the different vectors were ligated to obtain the ST8Sial-pEGFP-Cl recombinant vector and the recombinant lentiviral vector, respectively. PCR and DNA sequencing were used to identify recombinant vectors. Melanoma cells WM451 were transfected with different vectors. Cell line with stable ST8Sial over-expressing was established. ST8Sial mRNA level was checked by real-time PCR. STSSial protein expression level was checked by Western blot. Proliferation of the stable cells was assayed by CCK-8 method. The clony formation of stable cells was also performed. Results Both ST8Sial-pEGFP-Cl recombinant plasmid and STSSial over-expression lentiviral vectors were successfully constructed. The transfection efficiency of ST8Sial over-expression lentiviral vector was much higher than that of ST8Sial-pEGFP-Cl recombinant plasmid. A WM451 cell line with stable ST8Sial over-expression lentiviral vectors was established. Results showed that the over-expression of ST8Sial promoted the proliferation and colony formation of cells. Conclusions ST8Sial over-expression vectors are successfully constructed. The over-expression of ST8Sial promotes the proliferation and colony formation of WM451 cells.

A protein expression system for tandem affinity purification in Xanthomonas citri subsp. citri

Abstract Citrus canker, caused by the Gram-negative bacterium Xanthomonas citri subsp. citri (Xac), is one of the most devastating diseases to affect citrus crops. There is no treatment for citrus canker; effective control against the spread of Xac is usually achieved by the elimination of affected plants along with that of asymptomatic neighbors. An in depth understanding of the pathogen is the keystone for understanding of the disease; to this effect we are committed to the development of strategies to ease the study of Xac. Genome sequencing and annotation of Xac revealed that ∼37% of the genome is composed of hypothetical ORFs. To start a systematic characterization of novel factors encoded by Xac, we constructed integrative-vectors for protein expression specific to this bacterium. The vectors allow for the production of TAP-tagged proteins in Xac under the regulation of the xylose promoter. In this study, we show that a TAP-expression vector, integrated into the amy locus of Xac, does not compromise its virulence. Furthermore, our results also demonstrate that the polypeptide TAP can be overproduced in Xac and purified from the soluble phase of cell extracts. Our results substantiate the use of our vectors for protein expression in Xac thus contributing a novel tool for the characterization of proteins and protein complexes generated by this bacterium in vivo.

Construction of three new Gateway® expression plasmids for Trypanosoma cruzi

We present here three expression plasmids for Trypanosoma cruzi adapted to the Gateway® recombination cloning system. Two of these plasmids were designed to express trypanosomal proteins fused to a double tag for tandem affinity purification (TAPtag). The TAPtag and Gateway® cassette were introduced into an episomal (pTEX) and an integrative (pTREX) plasmid. Both plasmids were assayed by introducing green fluorescent protein (GFP) by recombination and the integrity of the double-tagged protein was determined by western blotting and immunofluorescence microscopy. The third Gateway adapted vector assayed was the inducible pTcINDEX. When tested with GFP, pTcINDEX-GW showed a good response to tetracycline, being less leaky than its precursor (pTcINDEX).

Cloning, sequence analysis, and prokaryotic expression vector construction of glycosyltransferase gene BcUGT8 from Bupleurum chinense / 中草药

Objective: To clone the full-length cDNA of the uridine diphosphate glycosyltransferase (UGT) gene in Bupleurum chinense (BcUGT8), which may be involved with the saikosaponin biosynthesis, and to construct the prokaryotic expression vector. The work will provide the foundation for its further function verification by in vitro expression and activity analysis of the purified protein. Methods: RACE and LD-PCR were used to clone the full-length cDNA of BcUGT8, on the basis of its partial cDNA sequence obtained from our previous high-flux sequencing by Roche (454) GS FLX system. The open reading form (ORF) was PCR cloned using primers with corresponding restriction enzymes cutting sites. The PCR products were digested with corresponding restriction enzymes and then were inserted in expression vector pET-28a (+) to construct the recombinant expression vectors. Results: The full-length cDNA of UGT gene was cloned from B. chinense, and the prokaryotic expression vector was obtained. Conclusion: The full-length cDNA cloning, sequence analysis, and prokaryotic expression vector construction provide a substantial foundation for follow-up bio-function analysis of BcUGT8 through protein expression, purification, and activity analysis in vitro.

Construction and identification of specific shRNA interference plasmid vector targeted to uPAR gene / 中国癌症杂志

Background and purpose: Urokinase-type plasminogen activator receptor is related to invasion and metastasis of tumor. Inhibition of uPAR expression in tumor cells results in reducing its metastasis. This study was aimed to construct an expression vector with short hairpin RNA (shRNA) of uPAR, which could pave the way for RNAi-mediated tongue squamous cell carcinoma therapy. Methods: Genome sequences of uPAR gene were retrieved from Genhank and cDNA was designed to code expression of shRNA for uPAR gene. The cDNA was synthesized and inserted into the eukaryotic expression vector pWH1, and the recombinant pWH1-uPAR expression vector was identified by enzyme cutting method. Then, pWH1-uPAR expression vector was transfected into tongue squamous cell carcinoma Ts cells by Lipofectomine 2000. At last, the expression of uPAR in Ts cells transfected with pWH1-uPAR expression vector was observed by RT-PCR, immunocytochemistry staining and Western blot. MTT assay was performed to measure the proliferation of Ts cell. Results: The uPAR shRNA eukaryotic expression vector was successfully constructed. Compared with Ts cells and Ts cells transfected with plasmid pWH1, the Ts cells transfected with pWHI-uPAR expression vector showed a lower mRNA and protein expression of uPAR. The inhibition rate of proliferation was 32.9% of Ts cells by transfected with pWHl- uPAR. Conclusion: The constructed uPAR shR.NA expression vector could inhibit the expression of uPAR in tongue squamous cell carcinoma, which may be helpful for further research on the function of uPAR and provide effective methods for therapy of tongue squamous cell carcinoma.

Establishment of PC12 cell line with stable inhibition of DAPK expression / 基础医学与临床

Objective To screen a cell line which stably suppresses DAPK expression and to observe the growth characters.Methods Four pairs of shRNA were designed,synthesized and inserted into the pDsRed1-N1-U6 vector.The recombinant plasmids were purified and transfected into PC12 cell.Meanwhile,a pDsRed1-N1-U6 vector was transfected as control.The cell clones were screened by G418,and the stable PC12 cell line was established.DAPK expression was detected by Western blot.MTT method and Flow Cytometry(FCM) assay were used to assess the growth characters of the cell line.Results The shRNAs were transfected into PC12 cell and the cell clones were successfully screened out.Of the four recombinant plasmids,the F2 was the best interfering shRNA.Beyond our expectation,the F1 recombinant plasmid had an enhanced effect on DAPK expression.Conclusion A stable PC12 cell line with stable inhibition of DAPK expression by was established using siRNA expression vectors.

Introduction To Basic Molecular Biologic Techniques For Molecular Imaging Researches / 대한핵의학회잡지

Molecular imaging is a rapidly growing field due to the advances in molecular biology and imaging technologies. With the introduction of imaging reporter genes into the cell, diverse cellular processes can be monitored, quantified and imaged non-invasively in vivo. These processes include the gene expression, protein-protein interactions, signal transduction pathways, and monitoring of cells such as cancer cells, immune cells, and stem cells. In the near future, molecular imaging analysis will allow us to observe the incipience and progression of the disease. These will make us easier to give a diagnosis in the early stage of intractable diseases such as cancer, neuro-degenerative disease, and immunological disorders. Additionally, molecular imaging method will be a valuable tool for the real-time evaluation of cells in molecular biology and the basic biological studies. As newer and more powerful molecular imaging tools become available, it will be necessary to corporate clinicians, molecular biologists and biochemists for the planning, interpretation, and application of these techniques to their fullest potential. In order for such a multidisciplinary team to be effective, it is essential that a common understanding of basic biochemical and molecular biologic techniques is achieved. Basic molecular techniques for molecular imaging methods are presented in this paper.