Construction and expression of trefoil factor 3 expressing vector for tandem affinity purification / 中国组织工程研究

BACKGROUND:As a novel growth factor, human intestinal trefoil factor (TFF3) can promote cel growth and migration, and increase cel resistance to apoptosis, and it plays a great role in maintaining the mucosa integrity, mucosa protection and repairing the injured mucosa, also it has been closely related to the tumor growth and progression. With the function of mucosa repair, and as the tumor biomarker, TFF3 has a promising clinical application, but its definite interacting protein and molecular mechanism is stil unclear. OBJECTIVE:To construct and express the TFF3 recombinant protein with the tandem tag of StrepII-6×His in the target cel s for further purifying its interaction protein in the native condition based on the tandem affinity purification technique. METHODS:The DNA sequence for the tag (StrepII-TEV-6×His) and TFF3 as template was got by chemical synthesis and PCR amplification respectively. They were fused by the restriction enzyme XbaI site, and the tag sequence was located at the C terminus of TFF3 protein. TFF3-tag fusion gene was cloned into the pCDNA3.0 using EcoRI+HindIII, thus the TFF3-tag expressing vector pTFF3-C-StH was constructed and transfected transiently into gastric cel AGS by lipofectin. The recombinant TFF3-tag protein was expressed and detected by western blot assay. RESULTS AND CONCLUSION:The expressing vector pTFF3-C-StH for tandem affinity purification was constructed successful y, and was confirmed further by restriction enzyme analysis and sequenced. The recombinant TFF3-C-StH protein of TFF3-tag was expressed in the AGS cel , and showed specific antigenicity by western blot assay. Thus this work provides experimental base for further purification of the TFF3 interacting proteins.

Reporter cell line-based screening for anti-varicella-zoster virus compounds / 中华微生物学和免疫学杂志

Objective To establish a novel method to screen for anti-varicella-zoster virus (VZV) compounds with our previously generated reporter cell line for VZV, MV9G. MethodsMV9G cells were directly infected with cell-free virus of Oka vaccine strain (vOka) for 2 hours( CFV direct-infection) or cocultured with vOka-infected MeWo cells containing cell-associated virus for 48 hours (CAV co-culture) to promote expression of the reporter gene firefly luciferase. Antiviral compounds including heparin, mannose-6-phosphate( M-6-P), acyclovir( ACV ), resveratrol and roscovitine were added in the medium before or after the virus infection. Inhibitory effects( IC50 ) of the antiviral compounds were analyzed by comparing firefly luciferase activities of MV9G cells in the presence of antiviral compounds with those in the absence. Results Antiviral compounds inhibited luciferase activities of MV9G cells activated by CFV direct-infection and/or CAV co-culture in different levels. The reductions of luciferase activities statistically correlated with those of viral foci shown by immunostaining with a monoclonal antibody against VZV immediate early 62 antigens (IE62) in controls. Among these compounds, heparin, M-6-P, and 2.5 μmol/L of roscovitine inhibited CFV-activated more strongly than CAV-activated luciferase activities, whereas ACV and resveratrol inhibited CAV-activated more strongly than CFV-activated luciferase activities. Cell-associated ACV-resistant strains,Kanno and rOka YSR, activated luciferase activities of MV9G cells, too. However, the inhibitory concentrations (IC50) of ACV to the ACV-resistant strains were much higher than those to the ACV-sensitive strains,pOka and CaGu. ConclusionThe CFV direct-infection and CAV co-culture assays were useful to screen for antiviral compounds targeting the early and late phases of VZV infection, respectively. The VZV reporter cell-based assays may provide a simple, rapid, sensitive, and high-throughput method to screen for anti-VZV compounds.

Biological synthesis and purification of spider dragline silk protein polymers containing RGD three peptide / 生物医学工程学杂志

Spider dragline silk is one of most perfect fibrous proteins in nature. As biomaterials, it has a wide application in tissue engineering due to its unique mechanical properties, good biocompatibility, slow degradation. In this paper, based on the highly repetitive sequence of spider dragline silk and with the introduced RGD peptide codons which involve cell adhesion, the DNA monomer sequence encoding RGD-spider dragline silk was synthesized, and then was used to construct the multimers by the strategy of "head to tail"; the multimers were ligated into prokaryotic expression vector pET-30a, and then the B121 (DE3) pLyS, were transformed the expression of recombinant protein was induced by the addition of IPTG. SDS-PAGE analysis shows that the molecular weight of products expressed here are 35KD and 60KD respectively in agreement with the desired. Western assay was used for determining the specification of products. Further, the purification process was groped for the producing of large quantity of synthetic proteins through high density fermentation.