Analysis of differential protein expression profile of HeLa cells stably transfected with Chlamydia trachomatis pORF5 gene / 中华微生物学和免疫学杂志

Objective To analyze the protein expression profile of HeLa cells transfected with pORF5 gene of Chlamydia trachomatis. Methods A lentiviral expression vector containing pORF5 gene was constructed. The lentiviral expression vector and helper plasmids were co-transfected into 293T cells to construct the recombinant lentivirus, which was used to infect HeLa cells. HeLa cells transfected with pORF5 gene and control HeLa cells were sorted out by flow cytometry. The isobaric tags for relative and absolute quantitation ( iTRAQ) approach combined with nano-liquid chromatography-tandem mass spec-trometry ( NanoLC-MS/MS) analysis was performed to understand protein expression profiles and to iden-tify and quantify the differentially expressed proteins in the pORF5-transfected HeLa cells ( pORF5-Hela) and the control HeLa cells. Quantitative real-time PCR ( qRT-PCR ) and Western blot analysis were performed to detect the expression of some proteins at mRNA and protein levels, respectively. Results HeLa cell line stably transfected with pORF5 gene and control HeLa cell line were constructed successful-ly. Totally 314 proteins were differentially expressed between the pORF5-HeLa and control HeLa cells, 159 of which showed increased expression and the other 155 showed decreased expression in pORF5-HeLa cells. The differentially expressed proteins were involved in many processes, such as metabolic process, immune response, biological adhesion and so on. Results of qRT-PCR showed that the expression of HIST1H1C(histone H1. 2C), HBA1(hemoglobin subunit alpha), PARK7(parkinson disease protein 7), HMGB1(high mobility group protein B1) and HMGB2 at mRNA level in pORF5-HeLa cells were up-regulated, while the expression of CLIC1 ( chloride intracellular channel protein 1 ) , KRT7 ( typeⅡ cy-toskeletal 7), SFN(14-3-3 protein sigma) and CDKN2A(cyclin-dependent kinase inhibitor 2A) were down-regulated. Western blot analysis confirmed the enhanced expression of HMGB1 and PRAK7 at pro-tein level. The results of qRT-PCR and Western blot analysis were consistent with proteomic data. Con-clusion Expression profiles for differentially expressed proteins between pORF5-HeLa and control HeLa cells were established successfully. The differentially expressed proteins regulated by pORF5 gene were found to be related to cell metabolism, proliferation, adhesion and so on, suggesting that pORF5 might promote the growth and proliferation of Ct by regulating protein expression and biological behavior of host cells.

Screen and identification of immunodominant fragment of pORF5 plasmid protein from Chlamydia trachomatis / 中国免疫学杂志

Objective:To investigate the immunogenicity of pORF5 plasmid protein,and further to screen and identify its im-munodominant domian.Methods: 10 different fragments of pORF5 gene including full length were amplified from the DNA of Chlamydia trachomatis serovar D by PCR and cloned into appropriate site of pGEX-6p vector to construct recombinant vectors after digested with BamHⅠand NotⅠrestriction endonucleases.After identification by PCR and sequencing,the recombinant plasmids were transformed into XL1 Blue E.coli to express the GST fusion proteins.ELISA and Western blot were carried out to identify the immunogenicity and immunoreaction of pORF5 plasmid protein.10 different fragments were reacted with sera from patients urogenitally infected with Chlamydia trachomatis, mouse polyclonal antibodies and mouse monoclonal antibodies of pORF5 plasmid protein with ELISA method.Results: pORF5 plasmid protein displayed strong immunogenicity and could induce a strong antibody response in human.The reactivity of human antibodies almost completely disappeared,when the native structure of pORF5 plasmid protein was de-stroyed.F6 that only lacked the N-terminal 66 amino acids was recognized by antibodies in ELISA as strongly as the whole pORF5 plasmid protein was.However,no other fragments were significantly recognized although there was a minimal reactivity of F2 and F3 with antibodies.Conclusion:pORF5 plasmid protein was an immunodominant antigen containing conformation-dependent epitope,and the C-terminal three quarters of pORF5 amino acid sequence was required for maintaining its immune dominance and conformation.The significance of the above findings lay a foundation for the further study on pORF5 protein function and vaccine development.

pORF5 plasmid protein of Chlamydia trachomatis induces IL-1βand IL-18 production through NALP3 inflammasome activation / 中国免疫学杂志

Objective:To investigate whether pORF5 plasmid protein of Chlamydia trachomatis(Ct) induces 1L-1βand 1L-18 production in THP-1 cells,and its potential molecular mechanism.Methods:pORF5 plasmid protein was used to stimulate THP-1 cells at different concentrations(0,3,6,12,24,36 μg/ml),then the inflammatory cytokines IL-18 and IL-1βwere detected by ELISA at the time of 0,8,16,24,36 h;The mRNA expression of NALP3 inflammasome were detected by Realtime-PCR,and Caspase-1 activity was determined by Western blot analysis.THP-1 cells were transfected with siRNA targeting NALP3 and ASC gene for 24 h or pretreated with Caspase-1 inhibitor(Z-YVAD-FMK) for 30 min,and subsequently stimulated with pORF5(24 μg/ml) for 24 h,then secretion of IL-1βand IL-18 were analyzed by ELISA.Results: The pORF5 plasmid protein induced THP-1 cells to secrete IL-1βand IL-18 by dose-and time-dependent manners,production of IL-1βand IL-18 reached their peaks(491 pg/ml and 186 pg/ml) at concentration of 24 μg/ml,and the peak amount of IL-1βand IL-18 occurred at 24 h and 16 h post-stimulation respectively.pORF5 plasmid protein in-creased mRNA expression of NALP3 inflammasome and activated Caspase-1 in THP-1 cells.NALP3 siRNA,ASC siRNA and Z-YVAD-FMK reduced pORF5-induced IL-1βand IL-18 production when compared with control groups(P<0.05).Conclusion:pORF5 plasmid protein could induce THP-1 cells to produce IL-1βand IL-18 through NALP3 inflammasome activation,which may play an important role in the pathogenesis in Ct infection.

Localization of human papillomavirus type 16 E6 protein and hDaxx in a human cervical carcinoma cell line HeLa and their effects on cell apoptosis / 中华皮肤科杂志

ObjectiveTo determine the subcellular localization of exogenous human papillomavirus type 16 E6 protein(HPV16 E6) and hDaxx in HeLa cells and their effects on tumor necrosis factor (TNF)-α-induced apoptosis.MethodsHeLa cells were transfected with plasmids pDsRed-monomer-C1/HPV16 E6,pEGFP-CI/hDaxx,pEGFP-C1 and pDsRed-monomer-C1 respectively.Subsequently,Western blot was carried out to quantify the expression of fusion proteins DsRed-HPV16E6 and EGFP-hDaxx in transfected cells,and laser scanning confocal microscopy to observe the subcellular distribution of HPV16 E6 protein and hDaxx.Some HeLa cells were divided into 5 groups:untransfected (control group),untransfected and treated with TNF-α(TNF-ot group),transfected with pcDNA3.1 (-) and treated with TNF-α(empty vector group),transfected with pcDNA3.1 (-)/HPV16 E6 and treated with TNF-α (HPV16 E6 group),cotransfected with pcDNA3.1(-)/HPV16 E6 and pcDNA3.1 (-)/hDaxx and treated with TNF-α (cotransfected group).After additional culture,the cells were collected and subjected to flow cytometry(FCM) to evaluate the apoptosis of cells as well as spectrophotometry to determine the relative activity of Caspase-8 and Caspase-3.ResultsWestern blot showed that both DsRed-HPV16 E6 and EGFP-hDaxx were expressed in HeLa cells.In Hela cells transfected with pDsRedmonomer-C1/HPV16 E6 or pEGFP-C1/hDaxx alone,the red fluorescence of HPV16 E6 was observed in the nucleus and cytoplasm,while the green fluorescence of hDaxx only in the nucleus; in those cotransfected with pDsRed-monomer-C1/HPVl6 E6,HPV16 E6 and hDaxx proteins were regionally aggregated near the nuclear membrane in nuclei,and hDaxx was partly translocated from the nucleus to the cytoplasm.The apoptosis rate and relative activity of Caspase-8 and Caspase-3 were statistically lower in HPV16 E6 group than in the empty vector group and cotransfected group(21.4％ ± 1.1％ vs.27.0％ ± 0.9％ and 32.5％ ± 2.1％,0.057 ± 0.003 vs.0.092 ±0.012 and 0.109 ± 0.013,0.054 ± 0.006 vs.0.093 ± 0.005 and 0.110 ± 0.004,all p＜ 0.01).Conclusions HPV16 E6 protein induces the partial translocation of hDaxx from the nucleus into the cytoplasm and colocalizes with hDaxx in the cells.The apoptosis of HeLa cells induced by TNF-α can be suppressed by HPV16 E6 protein,while the overexpression of hDaxx can attenuate the suppressing effect of HPV16 E6 protein on apoptosis in Hela cells.

Purification and immunological characteristics of monoclonal antibody 2H4 against Chlamydia trachomatis pORF5 plasmid protein / 中华微生物学和免疫学杂志

ObjectiveTo purify and characterize the monoclonal antibody (McAb) against Chlamydia trachomatis pORF5 plasmid protein.Methods The hybridoma cells stably secreting specific McAb against pORF5 were cultured in a large scale,and protein G purification by affinity chromatography was used to purify 2H4 McAb.ELISA was used to determine the antibody titer,and identify McAb isotype.Immunofluorescence assay (IFA) and Western blot were performed to detect McAb specificity.Results The purity of 2H4 antibody was 93％,the titer reached 1:1024,and 2H4 McAb was identified to belong to IgG2a isotype,2H4 McAb reacted strongly with the GST-pORF5 fusion protein and endogenous pORF5 protein expressed by Chlamydia trachomatis serovar A,D,L2,Chlamydia muridarum ( MoPn ),Chlamydia psittaci 6BC,but not other chlamydial plasmid proteins and Chlamydia pneumoniae(Cpn) AR39 strain.Conclusion2H4 McAb against pORF5 protein was successfully purified with a high titer and specificity which lay a foundation for further study on pORF5 protein structure and function.