Interferon-Stimulated Genes Response in Endothelial Cells Following Hantaan Virus Infection

The regulation mechanism of interferon (IFN) and IFN-stimulated genes is a very complex procedure and is dependent on cell types and virus species. We observed molecular changes related to anti-viral responses in endothelial cells during Hantaan virus (HTNV) infection. We found that there are two patterns of gene expression, the first pattern of gene expression being characterized by early induction and short action, as in that of type I IFNs,' and the other being characterized by delayed induction and long duration, as those of IRF-7, MxA, and TAP-1/2. Even though there are significant differences in their induction folds, we found that all of IFN-alpha/beta , IRF- 3/7, MxA, and TAP-1/2 mRNA expressions reached the peak when the viral replication was most active, which took place 3 days of post infection (d.p.i.). In addition, an interesting phenomenon was observed; only one gene was highly expressed in paired genes such as IFN-alpha/beta??(3/277-folds), IRF-3/7 (2.2/29.4-folds), and TAP- 1/2 (26.2/6.1-folds). Therefore, IFN-beta, IRF-7, and TAP-1 seem to be more important for the anti-viral response in HTNV infection. MxA was increased to 296-folds at 3 d.p.i. and kept continuing 207-folds until 7 d.p.i.. The above results indicate that IFN-beta works for an early anti-viral response, while IRF7, MxA, and TAP-1 work for prolonged anti-viral response in HTNV infection.

Colocalization of Interferon Regulatory Factor 7 (IRF7) with Latent Membrane Protein 1 (LMP1) of Epstein-Barr Virus

Interferon regulatory factor 7 (IRF7) is one of the transcriptional factors for the activation of type I Interferon (IFN) genes. It is known that IRF7 and the latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) are highly expressed in EBV type III latency cells, and LMP1 induces mRNA expression of IRF7. In this study, the expression pattern of endogenous IRF7 was observed in several B cell lines with or without EBV infection by immunofluorescence staining. IRF7 was localized in the cytoplasm of EBV-negative B cells and EBV type I latency B cell lines. However, IRF7 was located both in the cytoplasm and nucleus of EBV type III latency cell lines. In the Jijoye cell (type III latency cell), IRF7 was colocalized with LMP1 in the cytoplasm in a capping configuration, and their interaction was confirmed by co-immunoprecipitation of LMP1 and IRF7. This colocalization was confirmed by co-transfection of IRF7 and LMP1 plasmids in EBV-negative B cells. These results suggest that the IRF7 and LMP1 interact with each other, and this may relate to the mechanism whereby LMP1 exerts functional effects in B-lymphocytes.

The Effect of Naringin on the Lysophosphatidylcholine-induced Proliferation of Vascular Smooth Muscle Cells

BACKGROUND AND OBJECTIVES: Lysophosphatidylcholine (lysoPC), an atherogenic lysophospholipid, is known to induce the proliferation of vascular smooth muscle cells (VSMCs). Naringin is a flavonoid in grapes and grapefruits and has anti-inflammatory as well as antioxidative effects. We investigated whether naringin could protect VSMCs from the effect of lysoPC. Additionally, we investigated the changes of nuclear translocation of nuclear factor-kappa B (NF-kappa B). MATERIALS AND METHODS: VSMCs were prepared from the aorta of Sprague-Dawley rats. Near-confluent VSMCs were preincubated in media containing 0, 10, 100 micrometer naringin, and incubated with 0, 10, 20, 100 micrometer lysoPC. The degree of proliferation of VSMCs was evaluated with [H3]-thymidine incorporation and MTT assay. The changes of nuclear translocation of NF-kappa B in VSMCs were investigated with EMSA. RESULTS: LysoPC promoted the growth of VSMCs, whereas naringin inhibited the proliferative effect of lysoPC on VSMCs. MTT assay showed a 63+/-24% and 89+/-17% increase of cellular growth in the 10 and 20 micrometer lysoPC groups, respectively, as compared with the control group with media only (p<0.01). [H3]-thymidine incorporation assay also showed 61+/-25% and 92+/-25% increase in the 10 and 20 micrometer lysoPC groups, respectively (p<0.01). However, the growth of VSMCs was suppressed in the 100 micrometer lysoPC group (p<0.01). Naringin inhibited the proliferative effects of lysoPC on VSMCs by 34+/-5% (MTT assay) and 35+/-5% ([H3]-thymidine incorporation assay) in the 100 micrometer naringin group (p=0.01). The nuclear translocation of NF-kappa B was stimulated by lysoPC and suppressed by naringin. CONCLUSION: LysoPC promoted the growth of VSMCs, whereas naringin inhibited the proliferative effect of lysoPC on VSMCs. These effects of lysoPC and naringin are associated with the regulation of nuclear translocation of NF-kappa B.