PDF(Pubmed)
Abstract：
HIV infection of astrocytes leads to restricted gene expression and replication but abundant expression of HIV early genes Tat, Nef and Rev. A great deal of neuroHIV research has so far been focused on Tat protein, its effects on astrocytes, and its roles in neuroHIV. In the current study, we aimed to determine effects of Nef expression on astrocytes and their function. Using transfection or infection of VSVG-pseudotyped HIV viruses, we showed that Nef expression down-modulated glial fibrillary acidic protein (GFAP) expression. We then showed that Nef expression also led to decreased GFAP mRNA expression. The transcriptional regulation was further confirmed using a GFAP promoter-driven reporter gene assay. We performed transcription factor profiling array to compare the expression of transcription factors between Nef-intact and Nef-deficient HIV-infected cells and identified eight transcription factors with expression changes of 1.5-fold or higher: three up-regulated by Nef (Stat1, Stat5, and TFIID), and five down-regulated by Nef (AR, GAS/ISRE, HIF, Sp1, and p53). We then demonstrated that removal of the Sp1 binding sites from the GFAP promoter resulted in a much lower level of the promoter activity and reversal of Nef effects on the GFAP promoter, confirming important roles of Sp1 in the GFAP promoter activity and for Nef-induced GFAP expression. Lastly, we showed that Nef expression led to increased glutamate uptake and decreased glutamate release by astrocytes and increased astrocyte proliferation. Taken together, these results indicate that Nef leads to down-modulation of GFAP expression and alteration of glutamate metabolism in astrocytes, and astrocyte proliferation and could be an important contributor to neuroHIV.
摘要：
HIV感染星形胶质细胞导致基因表达和复制受限，但HIV早期基因Tat的大量表达，Nef和Rev.到目前为止，大量的神经HIV研究都集中在Tat蛋白上，它对星形胶质细胞的影响，以及它在神经HIV中的作用。在目前的研究中,我们旨在确定Nef表达对星形胶质细胞及其功能的影响。使用VSVG假型HIV病毒的转染或感染，我们发现Nef的表达下调了胶质纤维酸性蛋白（GFAP）的表达。然后我们发现Nef表达也导致GFAPmRNA表达降低。使用GFAP启动子驱动的报告基因测定进一步证实转录调节。我们进行了转录因子谱分析阵列，以比较Nef完整和Nef缺陷的HIV感染细胞之间转录因子的表达，并确定了八种表达变化为1.5倍或更高的转录因子：三种由Nef上调（Stat1，Stat5和TFIID）。和五个由Nef下调(AR，气体/ISRE，HIF,Sp1和p53）。然后，我们证明了从GFAP启动子中去除Sp1结合位点导致启动子活性水平低得多，并且对GFAP启动子的Nef效应逆转，证实Sp1在GFAP启动子活性和Nef诱导的GFAP表达中的重要作用。最后,我们发现Nef的表达导致星形胶质细胞对谷氨酸的摄取增加、谷氨酸的释放减少以及星形胶质细胞的增殖增加。一起来看,这些结果表明，Nef导致星形胶质细胞GFAP表达下调和谷氨酸代谢改变，和星形胶质细胞增殖，可能是神经HIV的重要贡献者。
