Xuxia Song

HCMV Induces Dysregulation of Glutamate Uptake and Transporter Expression in Human Fetal Astrocytes

Human cytomegalovirus (HCMV) infections are the leading cause of viral induced birth defects, affecting the central nervous system (CNS) primarily. Fetal CNS is especially vulnerable to CMV induced injury. As HCMV permissive cells, astrocytes are responsible for major glutamate transport and regulate extracellular levels of glutamate avoiding its accumulation which is implicated in neurodegenerative disorders. In this study, highly purified astrocytes isolated from human first trimester aborted fetal brain were infected with HCMV AD169, glutamate uptake function was detected by 3H labeling technic, and the expression level alterations of glutamate transporters (GLAST, GLT-1), glutamine synthetase (GS) and its activity were also investigated. Protein kinases C (PKC) inhibitor treatment was to identify whether PKC signalling involved in regulating glutamate uptake, protein expression of GLAST, GLT-1, GS and GS activity. Results indicated HCMV AD169 infection could modulate glutamate uptake, expression levels of GLAST, GLT-1, GS and it activity through PKC signalling, suggesting a great susceptibility of human fetal astrocytes to HCMV infection, which significantly alters the uptake and metabolism of an important excitatory amino acid, glutamate, may be a potential mechanism for HCMV associated neurological disease, and an effective therapeutic target in neural diseases.

Inhibitory effects of Ginsenoside Rb1 on apoptosis caused by HSV-1 in human glioma cells.

To investigate the inhibitory effects of Ginsenoside Rb1 (GRb1) on apoptosis caused by Herpes Simplex Virus-1(HSV-1) in Human Glioma Cells (U251), U251 cells were infected by HSV-1 at a multiplicity of infection of 5 and GRb1, GRb1+HSV-1, HSV-1 and control groups. MTT and cell apoptosis assays were used to detect the inhibitory effects of GRb1 on the apoptosis of U251 cells that caused by HSV-1 infection for various concentrations of drug and virus treatments by MTT assay. We found that in the 400 μg/mL GRb1 and 400 μg/mL GRb1+HSV-1 groups, MTT values were higher than control group at all times (P<0. 05). Moreover, the apoptosis rate in the 400 μg/mL GRb1+HSV-1 group was lower than the HSV-1 group (P<0. 05). These results confirmed that, at appropriate concentrations, GRb1 could inhibit nerve cell apoptosis in HSV-1 infections.

High-level expression, purification and study of bioactivity of fusion protein M-IL-2(88Arg, 125Ala) in Pichia pastoris

M-IL-2((88)Arg, (125)Ala) is a fusion protein comprising melittin genetically linked to a mutant human interleukin 2((88)Arg, (125)Ala). In this study, we constructed an expression system of M-IL-2((88)Arg, (125)Ala) in Pichia pastoris: GS115/pPICZα A/M-IL-2((88)Arg, (125)Ala), and achieved the high-level expression of the fusion protein. The maximum yield of the fusion protein M-IL-2((88)Arg, (125)Ala) reached up to 814.5mg/L, higher than the system in Escherichiacoli. The fusion protein was purified by means of ammonium sulfate fractionation, dialysis and nickel ion affinity chromatography. The molecular weight of the fusion protein is about 26kDa, conforming the theoretical value. And M-IL-2((88)Arg, (125)Ala) possesses strong antigen-specificity by Western blot detection. Bioassay results indicated that the fusion protein could directly inhibit the growth of human ovarian cancer SKOV3 cells and Hela cells in vitro. This study provides an alternative strategy for large-scale production of bioactive M-IL-2((88)Arg, (125)Ala) using P. pastoris as an expression host and paves the way to clinical practice.

Expression, Purification, and Characterization of a Functional Mutant Recombinant Human Interleukin-2

In the current study, a mutant recombinant human interleukin-2 (MhIL-2) was generated using site-directed mutagenesis. The bacteria transformed with plasmid pET15b-MhIL-2 were cultured in LB medium containing 0.6mM IPTG for 8 hours at 27°C. Approximately 90% of His-MhIL-2 was efficiently expressed in soluble form. Purification efficiency was optimized using a number of strategies, including nickel ion chelating chromatography, desalting chromatography, thrombin cleavage and Superdex 75 gel filtration chromatography. The final product had >95% purity. PBMCs, CD4+ and CD8+ T cell proliferation assays revealed that one such mutant has identical functional property to the wild-type hIL-2. In summary, we generated a mutant hIL-2 that is functionally identical to wild-type hIL-2.

DNA methylation level of promoter region of activating transcription factor 5 in glioma

Transcription factors, which represent an important class of proteins that play key roles in controlling cellular proliferation and cell cycle modulation, are attractive targets for cancer therapy. Previous researches have shown that the expression level of activating transcription factor 5 (ATF5) was frequently increased in glioma and its acetylation level was related to glioma. The purposes of this study were to explore the methylation level of ATF5 in clinical glioma tissues and to explore the effect of ATF5 methylation on the expression of ATF5 in glioma. Methylation of the promoter region of ATF5 was assayed by bisulfite-specific polymerase chain reaction (PCR) sequencing analysis in 35 cases of glioma and 5 normal tissues. Quantitative real-time PCR (qRT-PCR) was also performed to detect ATF5 mRNA expression in 35 cases of glioma and 5 normal tissues. Clinical data were collected from the patients and analyzed. The percentages of methylation of the ATF5 gene in the promoter region in healthy control, patients with well-differentiated glioma, and those with poorly differentiated glioma were 87.78%, 73.89%, and 47.70%, respectively. Analysis of the methylation status of the promoter region of the ATF5 gene showed a gradually decreased methylation level in poorly differentiated glioma, well-differentiated glioma, and normal tissues (P<0.05). There was also a significant difference between well-differentiated glioma and poorly differentiated glioma (P<0.05). ATF5 mRNA expression in glioma was significantly higher than that in the normal tissues (P<0.05). This study provides the first evidence that the methylation level of ATF5 decreased, and its mRNA expression was evidently up-regulated in glioma.中文概要目的研究临床胶质瘤标本中激活转录因子5 (ATF5) 启动子区CpG岛甲基化状态及临床意义。创新点首次发现在胶质瘤标本中ATF5的甲基化水平下调, 其表达水平下调。方法收集35临床胶质瘤组织及5例急性脑外伤组织作为对照, 应用亚硫酸盐测序技术检测ATF5的甲基化水平, 并结合临床病理资料进行分析;实时荧光定量聚合酶链式反应 (qRT-PCR) 检测所有标本中ATF5mRNA的表达水平变化。结论5例正常脑组织、10例低级别胶质瘤及25例高级别胶质瘤的甲基化比例分别为87.78%、73.89%和47.70% (图2), 两组相比差异有统计学意义 (P<0.05;图3a和3b);qRT-PCR结果表明, 与对照相比, 胶质瘤标本中ATF5表达水平上升 (P<0.05;图3d)。综上所述, 胶质瘤组织中ATF5基因启动子区CpG岛的甲基化状态对该基因的表达有重要意义。

Inhibition of Human Cytomegalovirus Infection by IE86-Specific Short Hairpin RNA-Mediated RNA Interference

To develop a gene therapeutic method for human cytomegalovirus (HCMV), the IE86 specific short hairpin (sh) RNA expressing vector was constructed and subsequently transfected into MRC-5 cells. After infection of these cells with HCMV AD169, expression of IE86 was reduced strikingly as compared to the control. In addition, the inhibitory effect corresponded to a decrease in viral DNA replication and the virus-induced cytopathic effect. Measurement of the virus yield demonstrated that infection of cells expressing IE86-specific shRNA resulted in suppression of the formation of infectious viral progeny. These observations indicate that IE86 can be used as an effective target against HCMV infection using RNA interference (RNAi) technology, which provides new possibilities for anti-HCMV studies.

Effect of Inducible Expressed Human Cytomegalovirus Immediate Early 86 Protein on Cell Apoptosis

Human cytomegalovirus is a common human pathogen that can cause life-threatening disease under certain conditions. During infection of host cells, the virus expresses regulatory proteins such as IE72 and IE86 that are important for viral propagation. IE86 plays a critical role in the modulation of viral replication as well as host cell cycle control and apoptosis. In this study, a Tet-On system was used to quantify the effect of IE86 on apoptosis and p53 expression. Our results indicate that IE86 inhibits tumor necrosis factor (TNF)-α induced apoptosis and that the anti-apoptotic activity of this viral protein correlates with its expression levels. In addition, IE86 did not alter the mRNA level of p53. The system developed should provide a method for functional analysis of human cytomegalovirus (HCMV) IE86 protein.

Antiviral effects of IFIT1 in human cytomegalovirus-infected fetal astrocytes

The prominent feature of human cytomegalovirus (HCMV) is cell tropism specificity for human fetal nervous system, which leads to severe fetal nervous system damage especially in first‐trimester gestation. In this study, human astrocytes isolated from fetal brain were infected with HCMV AD169 and whole genome transcriptome profile was performed. The results showed that the gene expression of interferon stimulated genes (ISGs), chemokine and chemokine receptors were significantly up‐regulated (P < 0.01). The antiviral replication effects of IFIT1 (Interferon‐induced protein with tetratricopeptide repeats 1, Fc = 148.17) was investigated. Lentivirus with IFIT1 overexpression or knockdown was transduced into astrocytes, respectively. The viral mRNA, protein expression and HCMV titers were determined. The results showed that IE1, IE2, pp65, and viral titers were significantly decreased in IFIT1 overexpression group and enhanced in the knockdown group compared with control one (P < 0.01). Taken together, this study revealed IFIT1 played an important antiviral role in HCMV infected fetal astrocytes. The prominent feature of human cytomegalovirus (HCMV) is cellular tropism specificity for human fetal brain nervous system leading to severe fetal nervous damage especially in first‐trimester gestation. In this study, human astrocytes isolated from first‐trimester fetal brain were infected with HCMV AD169 and IFIT1 was studied for its antiviral replication effects. The results provided insights into the function of IFIT1 as a key factor in antiviral defense contributing to development of targeted therapeutics to fetal brain with HCMV infection. J. Med. Virol. 89:672–684, 2017.

Effect of Human Cytomegalovirus Infection on Nerve Growth Factor Expression in Human Glioma U251 Cells

OBJECTIVE To explore the change of endogenic nerve growth factor (NGF) expression in human glioma cells infected with human cytomegalovirus (HCMV). METHODS U251 cells were cultured in RPMI 1640 culture medium and infected with HCMV AD169 strain in vitro to establish a cell model of viral infection. Morphologic changes of U251 cells were observed under inverted microscope before and after infection with HCMV. Expression of NGF gene and protein of cells was detected by RT-PCR and Western blotting before and after infection with HCMV. RESULTS The cytopathic effects of HCMV-infected cells appeared on day 5 after infection. However, differential NGF expression was evident on day 7. NGF expression was decreased significantly in U251 cells on day 7 after infection in comparison with control group (P < 0.05). CONCLUSION HCMV can down-regulate endogenous NGF levels in human glioma cell line U251.

Using the SELDI ProteinChip system to detect changes in protein expression in Vero cells after infection

Human herpes simplex virus 1 (HSV-1) causes facial, ocular, and encephalitic disease and is associated with latent infection and cancer. Here, we developed a means of studying the pathogenesis of HSV-1 infection at the protein level by using the SELDI Protein Chip to detect changes of protein expression in Vero cells cultured in vitro. After infection with HSV-1 and culture for 12, 24 or 48 h, cells were harvested and lysed. IMAC3 arrays were applied to SELDI-TOF-MS to detect proteomic differences before and after infection. The chip detected a series of differentially expressed protein peaks. Inte-restingly, both peaks at 16 912 Da and 17 581 Da corresponded precisely with the molecular mass of ISG15, which may participate in antiviral activity during the process of infection. Thus, the results we obtained can serve as a basis to study the pathogenesis of HSV-1 and the interaction between the virus and its host. In addition, they can help in the discovery of new therapeutic targets for treatment of HSV-1 infection.