Kaniowska Dorota, Kaminski Rafal, Amini Shohreh, Radhakrishnan Sujatha, Rappaport Jay, Johnson Edward, Khalili Kamel, Del Valle Luis, Darbinyan Armine
Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 1900 North 12th Street, Philadelphia, PA 19122, USA.
J Virol. 2006 Sep;80(18):9288-99. doi: 10.1128/JVI.02138-05.
The human polyomavirus JC virus (JCV) is the causative agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML), which is commonly seen in AIDS patients. The bicistronic viral RNA, which is transcribed at the late phase of infection, is responsible for expressing the viral capsid proteins and a small regulatory protein, agnoprotein. Immunohistochemical analysis of brain tissue from subjects with AIDS/PML revealed colocalization of the human immunodeficiency virus type 1 (HIV-1) transactivator, Tat, and JCV agnoprotein in nucleus and cytoplasm of "bizarre" astrocytes. In accord with this observation, we detected the copresence of agnoprotein and Tat in human astrocytes upon infection with JCV and HIV-1 or in astrocytic cells expressing these proteins after transfection. Interestingly, results from infection of human astrocytes with HIV-1 and JCV showed a decrease in the level of HIV-1 replication in cells that are coinfected with JCV. Conversely, a slight increase in the level of JCV replication was observed in the presence of HIV-1. The copresence of JCV and HIV-1 in astrocytes prompted us to investigate the possible cross-interaction of agnoprotein with Tat and its impact on HIV-1 gene transcription. Our results demonstrate that agnoprotein through its N-terminal domain associates with Tat and the interaction causes the suppression of Tat-mediated enhancement of HIV-1 promoter activity in these cells. Results from RNA and protein binding assays showed that agnoprotein can inhibit the association of Tat with its target RNA sequence, TAR, and with cyclin T1. Furthermore, agnoprotein is able to interfere with cross-interaction of Tat with the p65 subunit of NF-kappaB and Sp1, whose functions are critical for Tat activation of the long terminal repeat. These observations unravel a new pathway for the molecular interaction of these two viruses in biologically relevant cells in the brains of AIDS/PML patients.
人多瘤病毒JC病毒（JCV）是致命性脱髓鞘疾病进行性多灶性白质脑病（PML）的病原体，该病常见于艾滋病患者。在感染后期转录的双顺反子病毒RNA负责表达病毒衣壳蛋白和一种小的调节蛋白——agnoprotein。对艾滋病/PML患者脑组织的免疫组织化学分析显示，人类免疫缺陷病毒1型（HIV-1）反式激活因子Tat与JCV agnoprotein在“怪异”星形胶质细胞的细胞核和细胞质中共定位。与这一观察结果一致，我们在JCV和HIV-1感染后人星形胶质细胞中或转染后表达这些蛋白的星形胶质细胞中检测到agnoprotein和Tat的共存。有趣的是，HIV-1和JCV感染人星形胶质细胞的结果显示，与JCV共感染的细胞中HIV-1复制水平降低。相反，在存在HIV-1的情况下，观察到JCV复制水平略有增加。星形胶质细胞中JCV和HIV-1的共存促使我们研究agnoprotein与Tat可能的交叉相互作用及其对HIV-1基因转录的影响。我们的结果表明，agnoprotein通过其N端结构域与Tat结合，这种相互作用导致这些细胞中Tat介导的HIV-1启动子活性增强受到抑制。RNA和蛋白质结合试验结果表明，agnoprotein可以抑制Tat与其靶RNA序列TAR以及细胞周期蛋白T1的结合。此外，agnoprotein能够干扰Tat与NF-κB的p65亚基和Sp1的交叉相互作用，而NF-κB和Sp1的功能对Tat激活长末端重复序列至关重要。这些观察结果揭示了这两种病毒在艾滋病/PML患者大脑中生物学相关细胞中的分子相互作用的新途径。
