Analysis of mechanisms of demyelination in progressive multifocal leukoencephalopathy

JC病毒（JC virus，JCV）可引起人类进行性多灶性白质脑病（progressive multifocal leukoencephalopathy，PML），但其脱髓鞘机制尚不清楚。为了研究JC病毒感染的早期事件，包括病毒的附着、穿透和转运到细胞核，在此病毒复制发生，我们使用半定量PCR检测、ISH、激光扫描共聚焦显微镜和病毒复制测定。在接种后10分钟内在所有细胞系中观察到JCV进入。通过抗JCV VP 1抗体和唾液酸酶处理去除唾液酸残基来抑制病毒进入，这支持JCV VP 1作为配体发挥功能，并且JCV受体是含有唾液酸的细胞表面分子。此外，氯丙嗪，网格蛋白依赖性途径抑制剂，显着抑制JCV进入细胞核，表明JCV利用网格蛋白途径在进入细胞。Fr ...更多信息 由于近年来临床病理学研究发现人类嗜T淋巴细胞病毒I型（HTLV-I）可能是PML的一种潜在疾病，我们研究了HTLV-I编码的调节蛋白Tax是否激活JCV的转录。利用双荧光素酶分析和电泳迁移率变动分析（EMSA），我们发现HTLV-I Tax的表达以NF-κ B依赖的方式激活人神经细胞中JCV早期和晚期启动子的转录潜能。此外，我们还发现Tax结合蛋白特异性地存在于非神经细胞中，我们还发现，作为JCV晚期蛋白之一的未知蛋白增强了JCV启动子本身。这些结果使得基于病毒感染和在神经细胞中增殖的机制来建立针对PML的有效治疗成为可能。少

JC virus (JCV) causes in humans a demyelinating disease, progressive multifocal leukoencephalopathy (PML), but mechanisms of demyelination by JCV remain unknown.To investigate early events of JCV infection including attachment, penetration, and transport to the nuclei where viral replication occurs, we have analyzed the susceptibility of 15 different cell lines to infection using a semi-quantitative PCR assay, ISH, laser scanning confocal microscopy and a viral replication assay. JCV entry was observed in all cell lines within 10 min after inoculation. Inhibition of viral entry both by an anti-JCV VP1 antibody and sialidase treatment to remove sialic acid residues argues in favor that JCV VP1 functions as ligand and that JCV receptor is the cellular surface molecules containing sialic acids. In addition, chlorpromazine, a clathrin-dependent pathway inhibitor, significantly suppressed entry of JCV into nuclei, suggesting that JCV utilizes a clathrin pathway during the entry to cells. Fr … More om these observations it has been proved that JCV receptor is broadly expressed in the cells originated from various tissues and species.Because the recent clinicopathological analyses have disclosed that human T-lymphotropic virus type I (HTLV-I) could be an underlying disease of PML, we have examined whether the HTLV-I encoded regulatory protein Tax activates JCV transcription. Using a dual luciferase assay and an electrophoretic mobility shift assay (EMSA), we found the expression of HTLV-I Tax activated the transcriptional potential of both early and late promoters of JCV in human neural cells in a NF-κB-dependent manner. In addition, we demonstrated the presence of Tax-bound protein(s) which were specifically present in non-neural cells.We also found that agnoprotein, one of the JCV late proteins, enhanced the JCV promoter itself. These results make it possible to establish an effective therapy against PML based on the mechanism of viral infection and multiplication in the neural cells. Less