Patel Charvi A, Mukhtar Muhammad, Harley Stephen, Kulkosky Joseph, Pomerantz Roger J
The Dorrance H. Hamilton Laboratories, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
J Neurovirol. 2002 Apr;8(2):86-99. doi: 10.1080/13550280290049552.
Our recent studies have demonstrated that extracellular, recombinant human immunodeficiency virus type I (HIV-1) Vpr protein is highly neurotoxic in the microenvironment of differentiated mature human neurons and undifferentiated neuronal precursors. Although most of the direct neurotoxic effects of HIV-1 have been attributed previously to the envelope gene product, gp120, and the Tat regulatory protein, it was demonstrated that Vpr protein caused apoptosis comparable to that induced by gp120 protein in a dose-dependent manner in the neuronal system. Having observed the neurocytopathic effects of extracellular Vpr protein previously, the effects of virally expressed Vpr on nondividing, terminally differentiated human neurons were investigated. An HIV-1-based three-plasmid expression vector system was utilized to study the effects of intracellularly expressed Vpr. These virion preparations were then used to transduce neurons generated from the human neuronal precursor NT2 cell-line. Intracellularly expressed Vpr induced apoptosis within terminally differentiated neurons, as demonstrated by TUNEL assays. Additionally, virions lacking Vpr expression did not significantly induce apoptosis within these neurons. These results suggest that HIV-1 Vpr may also be leading directly to selective neurotoxicity through intracellular expression. Furthermore, human apoptosis gene microarray comparisons exhibited an up-regulation of Bcl-2-related mRNA, as well as other apoptosis genes involved in the mitochondrial apoptotic pathway, for the Vpr-transduced neuronal cells, when compared to Vpr-negative controls. Thus, Vpr delivered intracellularly, as well as extracellularly, is involved in the induction of significant neuronal apoptosis and may be one of the molecular mechanisms in HIV-1-induced encephalopathy.
我们最近的研究表明，细胞外重组人免疫缺陷病毒I型（HIV-1）Vpr蛋白在分化成熟的人类神经元和未分化的神经元前体细胞的微环境中具有高度神经毒性。尽管HIV-1的大多数直接神经毒性作用先前被归因于包膜基因产物gp120和Tat调节蛋白，但已证明Vpr蛋白在神经元系统中以剂量依赖的方式诱导与gp120蛋白相当的细胞凋亡。此前观察到细胞外Vpr蛋白的神经细胞病变效应后，研究了病毒表达的Vpr对不分裂的终末分化人类神经元的影响。利用基于HIV-1的三质粒表达载体系统研究细胞内表达的Vpr的作用。然后用这些病毒粒子制剂转导从人类神经元前体NT2细胞系产生的神经元。TUNEL分析表明，细胞内表达的Vpr在终末分化的神经元内诱导细胞凋亡。此外，缺乏Vpr表达的病毒粒子在这些神经元内未显著诱导细胞凋亡。这些结果表明，HIV-1 Vpr也可能通过细胞内表达直接导致选择性神经毒性。此外，与Vpr阴性对照相比，人类凋亡基因微阵列比较显示，Vpr转导的神经元细胞中Bcl-2相关mRNA以及参与线粒体凋亡途径的其他凋亡基因上调。因此，细胞内和细胞外递送的Vpr均参与显著的神经元凋亡诱导，可能是HIV-1诱导脑病的分子机制之一。
