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Objective To investigate the influence of early growth response gene-1 (EGR1) on the autophagy of host cells following infection with human T cell leukemia virus type 1 (HTLV-1).MethodsA HTLV-1-positive cell line MT2 was co-cultured with HeLa cells for 24 h to construct the virus early infection model.Immunoblotting assay was used to detect the expression of HTLV-1 core protein p19 and EGR1.Luciferase reporter gene analysis was used to detect the transcriptional activity of 5′-regulatory sequence of EGR1 at different time points after co-culturing.An effective small interfering RNA (siRNA) targeting EGR1 was screened out and transfected into HeLa cells by Lipofectamine 2000.Then the transfected HeLa cells were co-cultured with the HTLV-1-positive cell line MT2 for 24 h.Immunoblotting assay was used to detect HTLV-1 core protein p19, EGR1 and autophagy-related protein LC3.Real-time PCR was performed to detect viral load.Autophagosome was analyzed by immunofluorescence after co-culturing.Results The expression of EGR1 and the transcriptional activity of pEGR1-luc gradually increased after co-culturing HeLa cells with MT2 cells for 8 h (P<0.01).The expression of EGR1 was positively correlated with host cell autophagy following HTLV-1 infection.The effective siRNA for silencing the expression of EGR1 was obtained and named as siE2.The viral load, the expression of HTLV-1 core protein p19 and the proportion of LC3B/LC3A in the co-culture model were markedly down-regulated by RNA interference with siE2, which was concomitant with a persistent decrease of intracellular autophagosome (P<0.01).Conclusion EGR1 is associated with host cell autophagy and viral replication in HTLV-1 infection.
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Objective To explore the expression of early growth response gene-1 (EGR-1) in T cells that were positive for Tax protein of human T-cell leukemia virus type 1 (HTLV-1) and its possible reg-ulatory mechanism .Methods A series of expression structures carrying the regulatory elements of EGR-1 in different length and luciferase reporter genes were constructed .TaxP cells were transfected with the con-structs containing reporter genes and cultured with 5μmol/L of NF-κB inhibitor BAY 11-7082 or equal vol-ume of DMSO.After cultured for 24 hours the cells were collected to test the luciferase activity .BAY 11-7082 or equal volume of DMSO was added into the supernatant of TaxP cell culture to test the expression of EGR-1 protein by Western blot after 24 hours of culture .Tax and its mutants M22 and M47 were transfected into 293 T cells respectively to test the expression of EGR-1 protein by Western blot after 24 hours of culture . Results The expression structures carrying the regulatory elements of EGR-1 in different length and their mutants followed by luciferase reporter genes were successfully constructed .The luciferase activity in the cells transfected with the constructs containing the elements E 1 and E2 were higher than that transfected with E3, DelE and MutE, but the reporter gene expressions were decreased with the interference of BAY 11-7082 (P<0.01).However, there were no significant changes with the luciferase activity in the cells transfected by elements E3, DelE and MutE.Western blot analysis indicated that the expression of EGR-1 protein was significantly decreased with the interference of BAY 10-7082 .The expression of EGR-1 protein in M22 mu-tants-transfected 293 T cells were decreased significantly in comparison with those by wild type tax-and M47-transfected cells .Conclusion NF-κB was the key nuclear factor in regulating the expression of EGR-1 pro-tein in Tax-positive T cells .
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Objective:To discuss the effect and mechanism of autophagy inhibitor 3-MA on arsenic trioxide inducing apoptosis of acute T-cell leukemia cell line Jurkat cells.Methods:Proliferation inhibition of Jurkat cells treated with arsenic trioxide was detected by XTT.Morphological characteristics of Jurkat cells treated with different concentrations arsenic trioxide were observed by electron mi-croscope.Microtubule-associated protein 1 light chain 3B (LC-3B) protein expression was detected by Western blot and flow cytome-try.Apoptosis rates of Jurkat cells treated with 3-MA combining arsenic trioxide were detected by flow cytometry using AnnexinV-FITC/PI double staining.Results:Arsenic trioxide inhibited the growth of Jurkat cells in a dose and time dependence.We observed different morphological characteristics of autophagy , apoptosis and necrosis accompanying more autophagosomes in Jurkat cells which were treated with arsenic trioxide 2.5,5,10 μmol/L after 24 h.LC3B mean fluorescence intensity (MFI)relative multiples were(3.1±0.2) fold,(4.6±0.31)fold,(34.2±4.5)fold with 5 μmol/L arsenic trioxide treated Jurkat cells 0,24,48 h,and the P values between each of the two groups were less than 0.05,which increased depending time consistently with the growth inhibition rates.LC-3B protein expression gradually increased treated Jurkat cells with arsenic trioxide after 24 h,48 h.The growth inhibition rate (60.6±8.3)%was significantly different treated with arsenic trioxide combining 3-methyl adenine ( 3-MA ) while it was ( 33.4 ±9.1 )% treated with arsenic trioxide alone, however, LC-3B protein expression gradually decreased.Jurkat cell apoptosis rate ( 44.96 ±3.60 )% was significantly increased treated with arsenic trioxide combining autophagy inhibitor(3-MA) while it was (2.94±0.26)% treated with arsenic trioxide alone, and this difference was statistically significant.Conclusion: 3-MA increased apoptosis rates of Jurkat cells inducing by Arsenic trioxide and it may be related with inhibition of autophagy and induction of apoptosis.
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Objective To explore the regulatory effects of HTLV-1 ( human T-cell leukemia virus type 1 ) Tax protein on the expression of HMGB 1 ( high mobility group box 1 ) gene in T cells .Methods Total RNA and protein were extracted from Tax +-T cells ( TaxP ) , Tax--T cells ( TaxN ) and Jurkat cells which were stably transfected with pCMV-Tax and pCMV-Neo, respectively.Then, the expression levels of HMGB1 mRNA and protein in different CD 4+T cells were analyzed by real-time PCR and Western blot (WB).By using liposome-mediated method, pGL3-HMGB1-luc reporter genes and pGL3-neo-luc were tran-siently transfected into TaxP and TaxN cells and the basal transcriptional activity was observed in different T cells.Additionally, pCMV-Tax and pGL3-HMGB1-luc reporter genes were also co-transfected into Jurkat cells and the regulatory effects of Tax protein on HMGB 1 gene was detected .The chromatin immunoprecipi-tation (ChIP) assay was used to identify HMGB1 genomic sites directly targeted by Tax .Results The ex-pression levels of HMGB1 mRNA and protein in Tax+-T cells ( TaxP) were higher than those in Tax--T cells (TaxN).The transcription regulation trends for HMGB1 gene in TaxN and TaxP cells were similar but not identical in diverse T cells.pHLuc3 (containing -504-+83 HMGB1) showed the highest transcriptional ac-tivity of HMGB1 gene in both TaxP and TaxN cells , but HMGB1 transcriptional activity of pHLuc 6 in TaxP cells was significantly stronger than that in TaxN cells .Luciferase assays also showed that Tax protein promo-ted the transcription of HMGB1 gene in a dose-dependent manner .The ChIP assay further confirmed that Tax protein enriched at the HMGB1 region of -1163--1043.Conclusion The region of nt -504--383 is essen-tial for the basal promoter activity of -1163-+83 HMGB1 gene originated from pHLuc 6 reporter plasmid , and Tax protein enriched probably at the HMGB 1 site of -1163--1043 enhances HMGB1 transcription.
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Objective To study the role of endothelial cells on the inflammatory cytokine release in septic shock through the septic shock serum stimulating human primary endothelial cells (HPAEC) and peripheral blood mononuclear cells(PBMC).Methods PBMC isolated from healthy people by density gradient centrifugation.HPAEC cell surface markers CD144 and von Willebrand factor(vWF) molecule expression by RT-PCR and Western blot.Serum levels of IL-6,TNF-α,MCP-1 from septic shock patients and healthy human detected by ELISA.HPAEC and PBMC were stimulated with the isolated serums and LPS,respectively.ELISA was used to detect the supernatant IL-6,TNF-α,MCP-1 levels.HPAEC membrane molecules ICAM-1 expression was detected by flow cytometry with serum shock and LPS stimulation.Supernatant levels of IL-6,TNF-α,MCP-1 of HPAEC with S1P1 receptor agonist CYM-5442 pretreatment was detected by ELISA after shock serum stimulation.Results Endothelial cell markers CD144 and vWF molecules could be detected in the HPAEC.Levels of inflammatory cytokines IL-6,TNF-α,MCP-1 in patients with septic shock serum were significantly higher than healthy people (P＜0.01).PBMC and HPAEC with LPS or shock serum treatment respectively,compared with normal group,levels of inflammatory cytokines in the culture supernatant were significantly higher(P＜0.01).For PBMC,the level of inflammatory cytokines between shock group and LPS group were not significantly different (P＞0.05).But for HPAEC,levels of inflammatory cytokines in the supernatant of the shock group compared to the LPS group was significantly higher (P＜0.01).Similarly,when two cells after LPS stimulation,IL-6,TNF-α levels of HPAEC's supernatant were significantly lower than PBMC' s (P＜0.01),MCP-1 levels was no difference (P＞ 0.05).But when the stimulation of shock serum,HPAEC of IL-6,TNF-α levels and PBMC no significant difference (P ＞0.05).MCP-1 was significantly increased (P＜0.01).Shock patients serum stimulation S1P1 receptorspecific agonist CYM-5442 pretreatment of HPAEC with pretreatment of S1P1 receptor specific agonist CYM-5442,the culture supernatant of inflammatory cytokines IL-6,TNF-α,MCP-1 levels were significantly lower (P＜0.01).Conclusion Endothelial cells may play a central role on the release of inflammatory cytokine during septic shock.
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Objective To investigate the influence of extracellular high mobility group box 1 (HMGB1) on viral replication in HTLV-1 infected T cells.Methods HMGB1 in culture supernatants of adult T-cell leukemia virus 1 (HTLV-1) virus-negative cell:Jurkat,MOLT4 cells and HTLV-1 virus-positive cells:MT2,MT4,was detected by ELISA;The HTLV-1 long terminal repeat reporter gene (pHTLV-1-LTR-luc) was transfected into MT2 cells by Tfx-50-mediated transfection,and 0.25,0.50,0.75 μg/ml of HMGB1 polyclonal antibody(HMGB1 PcAb) and its isotype control rabbit IgG antibodies,0.03,0.1,0.3 μg/ml rhHMGB1 and its control PBS,were added into culture supernatant respectively,then luciferase activity was detected after 48 h;Similarly,0.25 μg/ml HMGB1 PcAb and the isotype control antibody,0.3 μg/ml rhH-MGB1 and the control PBS were added to the culture supernatant of MT2 cell,the viral gene,pol1,pol2,gag,env,etc,were performed by real-time PCR.Results Culture supernatant HMGB1 levels has no significant difference between HTLV-1 positive cells MT2 and MT4 and the other two virus-negative T cell lines;Compared with isotype control antibody group,the culture supernatant,to which is added 0.25 μg/ml HMGB1 PcAb,can significantly inhibit the HTLV-1-LTR transcriptional activity and suppress the expressions of the viral gene pol1,pol2,gag,env.Compared with the control PBS,0.3 μg/ml rhHMGB1 significantly promotes the transcriptional activity of the HTLV-1-LTR and the expressions of the viral gene pol1,pol2,gag,env.Conclusion The extracellular HMGB1 can promote viral replication of HTLV-1 infected T cells.
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Objective To explore the effect of HTLV-1 (human T-cell leukemia virus type 1 ) Tax protein on the DcR3 gene expression in T cells.Methods The construction of DcR3 (-1010 bp to +114 bp) luciferase reporter gene; MT2,TaxP,and Jurkat E6-1 cells were transfected with DcR3 luciferase reporter gene (pGL3-DcR3-1uc) using liposomes according to the manufacturer's instructions.For the control group,pGL3-basic replaced it respectively.At 48 h after incubation,luciferase activity was measured with a luciferase assay system; Jurkat cells were transfected with pCMV-Tax-Bam using liposomes,and total RNA was extracted from the cells at 48 h after incubation.Reverse transcription was performed using standard protocols.Then real time PCR with primers DcR3 and 3-actin was conducted;The expression of DcR3 protein was detected by flow cytometry in MT2,TaxP,and Jurkat cells.Results The construction of DcR3 luciferase reporter gene is identified correctly; The detection of luciferase activity showed that the luciferase activity of experimental group in MT2 cells was increased by (32.07±12.43)-fold,of which in TaxP cells was increased by ( 13.27±4.04)-fold,and the luciferase activity of experimental group in Jurkat cells was increased by ( 1.26±0.49 ) -fold.And there is statistic significance about the relative luciferase activity of experimental group in MT2 cells and TaxP cells compared to the relative lueiferase activity of experimental group in Jurkat cells respectively ( P＜0.01 ) ; The result of real-time PCR showed that the level of DcR3 mRNA in the experimental group was higher compared with the control group(P＜0.05) ; The result of FCM shows the expression of DcR3 protein in MT2,TaxP cells is higher than that in Jurkat cells( P＜0.05 ).Conclusion Tax protein can promote the expression of DcR3 gene in T cells.
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Objective To research the relation of early growth response gene-1(EGR-1) and NF-κB in human T-cell leukemia virus type 1(HTLV-1) Tax protein positive cells. Methods RT-PCR was used to amplify the aimed segments EGR-1 cDNA which was then inserted into an eukaryotic expression plasmid pcDNA3.0 to construct pcDNA3.0-EGR-1. The constructed plasmid was transfected into TaxN and TaxP cells by Tfx-50-mediated transfer method, the expression levels of EGR-1, p65 and Tax mRNA in transfected cells were assay by RT-PCR after 48 h post-transfection, the proteins of EGR-1 and p65 were detected by Western blot after 48 h post-transfection too. The constructed plasmid and pNF-κB-luc reporter gene plasmid was co-transfected into TaxN and TaxP cells by Tfx-50-mediated transfer method, and the activity of luciferase was assay after 48 h post-transfection. Results The results showed that the eukaryotic expression plasmid pcDNA3.0-EGR-1 was successfully constructed. The mRNA and protein expression of EGR-1 could be promoted significantly by Tax. EGR-1 can promote the mRNA and protein expressions of p65 in TaxP cells, the activity of NF-κB was up-regulated by EGR-1 too. Conclusion EGR-1 maybe involve in adult T-cell leukemia(ATL) by increasing the activation of NF-κB.
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Objective To study the effects of the adult T cell leukemia virus type 1(HTLV-1) Tax protein on T lymphocytes self-reactive growth hormone(GH). Methods The expression of the growth hormone protein was measured by Western blot in TaxP and TaxN cells, which expresses HTLV-1 Tax or no. The location of growth hormone in the TaxP and TaxN cells were detected by LSCM(laser scanning confocal microscope). The level of growth hormone mRNA in TaxP and TaxN cells was measured by RT-PCR. The pGL2-GH-luc was transfected in TaxN and TaxP cells by Tfx-50-mediated transfection to assay transcriptional activity. The pNF-κB-luc, pAP-1-luc and pNFAT-luc was transfected into TaxP cells with pcDNA3.0-GH by Tfx50 to test bioactivity of the nuclear transcription factors. Results The mRNA and protein expression of GH could be promoted significantly by Tax. Relative to the TaxN cells, the transcriptional activity of GH was significantly increased about 6.37 times in TaxP cells(P＜0.05). Overexpression of GH can increase the activity of NF-κB about 1.7 times in TaxP cells (P＜0.05). Conclusion GH maybe involve in adult T-cell leukemia(ATL) through activating NF-κB.