Molecular mechanisms of IL-8 gene expression by the immediate early gene products of cytomegelovirus

我们先前观察到人类巨细胞病毒(CMV)感染可诱导THP-1细胞产生大量白介素8(IL-8)。因此，我们检测了巨细胞病毒即刻早期(IE)基因产物对人星形细胞瘤细胞系U373 MG产生IL-8的影响。与对照载体相比，瞬时或稳定地转染人CMV IE1而不转导CMV IE2基因可显著增加IL-8蛋白的分泌和IL-8mRNA的表达。此外，在由人IL-8基因转录调控区驱动的嵌合萤火虫荧光素酶报告基因和CMV IE1共转染的U373 MG细胞中，荧光素酶活性得到增强。此外，通过在IL-8基因调节区的AP-1或NF-kB因子结合元件中引入突变，IE1基因介导的荧光素酶活性的增强被取消，正如先前在CMV感染的细胞中观察到的那样。最后，Western blotting和免疫组织化学分析表明，CMV IE1基因产物增加了核因子-kB复合体p65移位到细胞核中的数量。总之，CMV IE1基因的表达可能足以激活AP-1和NF-kB，导致IL-8基因的表达。

We previously observed that human cytomegalovires (CMV) infection induced a massive production of an interleukin-8 (IL-8) in a THP-1 cell. Hence, we examined the effect of CMV immediate early (IE) gene products on IL-8 production by the human astrocytoma cell line, U373MG. Transiently or stably transfection with CMV IE1 but not with CMV IE2 gene significantly augmented IL-8 protein secretion and IL-8 mRNA expression, compared with transfection with a control vector. Moreover, luciferase activity was enhanced in U373MG cells that were co-transfected with CMV IE1 and a chimeric firefly luciferase reporter genes driven by the transcriptional regulatory region of the human IL-8 gene. Furthermore, IE1 gene-mediated enhancement of luciferase activities was abolished by the introduction of the mutation into AP-1 or NF-kB factor binding elements in the regulatory region of the IL-8 gene, as previously observed on CMV infected cells. Finally, Western blotting as well as an immunohistochemical analysis demonstrated that CMV IE1 gene products increased the amount of p65 of NF-kB complexes translocated into the nuclei. Collectively, CMV IE1 gene expression may be sufficient to activates AP-1 and NF-kB, resulting in IL-8 gene expressions.