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Objective: To establish a tetracycline-induced gene knockdown system and study the effect of YAP1 on the function of gastric cancer cells. Methods: We constructed pLKO.1-tetON-YAP1 knock-down lentivirus and detected the vector by enzyme digestion and sequencing. Gastric cancer cell lines SGC-7901 and MKN-28 were infected with lentivirus, and YAP1 knocked-down gastric cancer cell lines induced by DOX were established. The mRNA level of YAP1 was detected by RT-qPCR, and the protein level of YAP1 was detected by Western blotting. Cell proliferation was detected by plate cloning experiment, and cell migration was detected by scratch-healing assay and Transwell assay. Results: The results of double enzyme digestion showed two bands at 6 000 bp and 3 000 bp, and that the sequencing results were consistent with the designed shRNA sequence. In the DOX-induced group, the mRNA and protein levels of YAP1 in gastric cancer cells infected with pLKO.1-tetON-YAP1 lentivirus significantly decreased compared with those in non-induced group. In the plate cloning experiment, the number of clones in shYAP1 groups decreased significantly after DOX induction, but there was no significant change in the non-induced group. Scratch-healing assay and Transwell assay showed that after DOX induction, the cell migration ability of shYAP1 groups was inhibited, but without significant change in the non-induced group. Results: We have successfully established a tetracycline-induced lentivirus system, and knocked down YAP1 gene of gastric cancer cells with this system. The proliferation and migration of gastric cancer cells are inhibited by YAP1 in this tetracycline induced lentivirus system.
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Objective To construct recombinant plasmids of SIK2 cDNA and its truncated mutants and induce its expression in E.coil.Methods We designed primers of SIK2 and its truncated mutants.The gene fragments of SIK2,SIK2-Δ1 (280-926),SIK2-Δ2 (400-926),SIK2-Δ3 (1-400),and SIK2-Δ4 (700-926)were amplified by polymerase chain reaction (PCR)and cloned into pGEX-4T-2 vector to construct recombinant plasmids with GST. The plasmids were transformed into E.coil BL2 1 respectively,and induced with IPTG to express fusion protein. The results were confirmed by Coomassie blue staining and Western blot.Results We successfully constructed recombinant plasmid of SIK2 cDNA and its truncated mutants.Coomassie blue staining and Western blot resutls showed that these plasmids were induced to be expressed in E.coil BL21.Conclusion SIK2 cDNA and its truncated mutants were overexpressed in E.coil BL2 1 ,which lays expereimental foundation for further study on the function of each domain of SIK2 .
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Objective To construct a shuttle plasmid for inducible gene expression in Borrelia burgdorferi (B.burgdorferi) with an advantage of flexible genetic manipulation.Methods The IPTG-inducible lac repressor/operator system from Escherichia coli (E.coli) was adopted and modified in the current study.The plasmid shuttle vector was developed by inserting multiple cloning sites,FLAG and HA tags into the shuttle vector by molecular cloning approaches.The target gene was inserted at the site under the control of the promoter (Tn5 derivate) in plasmid pQE30.This promoter contained two lac operators and a codonoptimized lacI gene driven by flaB promoter.Results A plasmid shuttle vector,pJJ275,was successfully constructed with the ability to express target genes in B.burgdorferi in the presence of IPTG.By using this system,a HA-tagged rpoS gene was introduced into the typical infectious strain B.burgdorferi B31.The target gene expression induced by IPTG was confirmed at transcriptional and translational levels.The RpoS dependent virulence factor of Borrelia,OspC,was also detected,indicating that the expressed protein was functional.Conclusion The constructed plasmid shuttle vector can express exogenous genes in B.burgdorferi with an inducible feature and an advantage of flexible genetic manipulation.It can be applied for genetic manipulation of B.burgdorferi involved in gene regulation and complementation.
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Objective To construct the secretory expression vector of recombinant human C-reactive protein(rhCRP) for its se-cretory expression in Pichia pastoris ,rhCRP was expressed as a secretory protein and purified ,and the immunity reactivity of the purified protein was identified .Methods The DNA fragment of rhCRP which was designed and synthesized was cloned into pPICZαA vector .Recombinant plasmid pPICZαA/rhCRP was linearized by SacⅠand transformed into Pichia pastoris X-33 by elec-trotransformation .The rhCRP was secreted into the medium under the methanol induction .RhCRP was purified by Histamine affin-ity chromatography .The purified rhCRP was identified by SDS-PAGE and Western blotting ,and its immunity reactivity and stabili-ty was identified by indirect ELISA .Results The pPICZαA/rhCRP expression vector was successfully constructed .The rhCRP of 23 × 103 was inducted and successfully expressed as a secretory protein by the recombinant Pichia pastoris strains .The rhCRP was purified by one step up to 90 .42% purity ,and it was showed good immunity and stability by indirect ELISA .Conclusion The rh-CRP with higher purity and immunoreactivity was successfully obtained by using the Pichia pastoris expression system ,which pro-vided an important experimental basis for producing anti-human CRP antibodies and developing testing CRP reagent .
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We report the construction of two vectors for Escherichia coli: pUC72, for molecular cloning, and pPLT7, for thermal-induced expression. The main feature of pUC72 is a novel polylinker region that includes restriction sites for Nde I and Nco I which provide an ATG codon for proper translation initiation of expressed genes. Vector pPLT7 is ideal for thermo-inducible expression in host cells that carry the cI857 repressor gene. The use of pPLT7 was validated by the successful expression of the genes encoding carp and porcine growth hormones. These vectors provide novel cloning possibilities in addition to simple, non-expensive, high level expression of recombinant proteins in E. coli.
Subject(s)
Base Sequence , Cloning, Molecular , DNA Fragmentation , Escherichia coli/genetics , Gene Expression , In Vitro Techniques , Proteins/genetics , Methods , Polymerase Chain Reaction , MethodsABSTRACT
Objective:To obtain human S100A2-GST fusion protein for further research on human S100A2(hS100A2)protein function and its interactions with other proteins and systems.Methods:hS100A2 gene from pHAHA-hS100A2 was subcloned into an expression vector pGST-moluc to construct pGST-moluc-hS100A2.The new plasmid was identified by digestion with XhoⅠand EcoRⅠ.The recombinant BL21 was induced with IPTG to express recombinant fusion protein hS100A2-GST,which was purified by Glutathion-Sepharose 4B ball beads,identified by SDS-PAGE and Western Blot,and quantified by Bradford method.Results:After the digestion,the recombinant plasmid was cutted into two fragments,300 bp and 5kb.After treated with IPTG,the recombinant BL21 strain expressed a protein,which was about 36 kD and was recognized specifically by an-ti-hS100A2.Its yield was 5 mg/L bacterial culture.After isolated by Glutathion-Sepharose 4B ball beads,its purity was 92%.Conclusion:hS100A2-GST expression plasmid pGST-moluc-hS100A2 was constructed successfully.hS100A2-GST fusion pro-tein could be expressed in Escherichia coli with higher yield and isolated with higher purity,which lays the foundation for the follow-up of the hS100A2 research.
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In order to construct the expression recombinant of human receptor associated protein (RAP), optimize its expression condition and obtain the recombinant protein after expression with high efficiency, two prokaryotic expression vectors-pT7-PL and pET-28a(+) were used to construct the expression recombinant containing RAP cDNA, and the expression efficiency of two kinds of expression E. coli of BL21 strains was compared. The effect of different induction conditions on the expression of recombinant RAP was observed. After recombinant protein was purified with Ni+-nitrilotriacetic acid (Ni+-NTA) affinity chromatogram, its binding ability with microphage was observed. The results showed that two recombinant plasmids both obtained high expression of RAP. The expression levels of RAP in plasmid pT7-PL-RAP in BL21 (DE3, plysS) strain were significantly higher than in BL21 (DE3) strain. The expression of pT7-PL-RAP in the presence of chloramphenicol was higher than in the absence of chloramphenicol, and most of the inducible expressed RAP was soluble. The RAP which was purified by Ni+-NTA resin could strongly bind with the RAW264.7 cells rich in low density lipoprotein receptor (LDLR) family receptors. It was concluded that the expression condition of recombinant RAP was optimized and functional RAP was obtained, which offered a good foundation for the further production of RAP as research tool.
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Objective: To obtain a prokaryotic expression vector containing saliva binding region (SBR) gene of Streptococcus mutans. Methods: By directional cloning method, SBR gene fragment was cloned into the expression vector pcMVT7, the recombinant plasmid pcMVT7-SBR was transformed to E.coli JM109 (DE3). The gene expression was induced with IPTG. Restriction endonuclease and DNA sequencing techniques were used to identify the recombinant plasmid DNA, and finally target protein was purified by affinity chromatography. Results:The DNA sequence of SBR in the reconstructed vector pcMVT7-SBR was in corresponding with the initial design. The C-terminal 6?His tagged SBR fusion protein was expressed in JM109(DE3) and was purified by affinity chromatography. The expression rate of target protein was 29.73%. Conclusion:The recombinant expression plasmid pcMVT7-SBR was constructed.