Mechanisms of retrovirus-induced T and neural cell death

描述（由申请人提供）：我们研究的一个主要目标是使用名为ts 1的MoMuLV-TB病毒突变体了解神经和免疫系统中逆转录病毒诱导细胞死亡的致病机制。ts 1感染的小鼠通常表现出T细胞和神经元的选择性耗竭，导致的疾病类似于人类艾滋病。像HIV一样，ts 1似乎直接破坏T细胞，但间接破坏神经元。后者可能是由于神经胶质氧化还原支持的丧失以及从受感染的神经胶质细胞释放氧化剂、神经毒素（例如谷氨酸）和促炎细胞因子。直到最近，我们对艾滋病病毒或ts 1感染后导致神经元和T细胞损失的原因知之甚少。我们所知道的是，tslenv基因中的单个突变导致tslgPr 80 ENV在感染细胞的内质网（ER）中积累，并且这种异常是感染动物中免疫缺陷和神经变性的原因。ts 1感染多种细胞类型，但仅在感染的T细胞和星形胶质细胞中gPr 80 ENV的转运是低效的，导致gPr 80 ENV在ER中积累。因此，我们实验室的工作一直集中在ts 1感染对这两种细胞类型的影响上。我们现在知道，这种细胞类型特异性的异常病毒蛋白积累（至少在星形胶质细胞中）在这些细胞中选择性诱导凋亡中起着关键作用。鉴于ts 1诱导的疾病和HIV诱导的疾病之间的几个相似性，有趣的是注意到最近其他人的研究表明，ER中gp 160的保留与HIV感染在CD 4 + T细胞中的细胞病变效应之间存在类似的关系。我们的中心假设是，ER是ts 1 gPr 80 ENV介导的细胞凋亡效应启动的主要位点，并且ts 1 gPr 80 ENV未能移出ER激活ER超载反应（EOR）和未折叠蛋白反应（UPR），随后钙超载诱导线粒体应激，并在受感染的星形胶质细胞中产生过量的活性氧和谷胱甘肽，导致星形胶质细胞和T细胞死亡。随着星形胶质细胞巯基氧化还原支持的丧失以及氧化剂和神经毒素从受感染的星形胶质细胞的释放，最终结果是神经元死亡。我们现在提出确定上述假设是否正确，以确定星形胶质细胞如何杀死神经元，并确定由ts 1诱导的T细胞死亡是否也涉及gPr 80 ENV积累和氧化应激。更重要的是，我们希望我们从这些研究中获得的知识将使我们能够找到预防这些事件的方法。我们的具体目标是：1）证实gPr 80 ENV积累，以及由此产生的ER应激和线粒体应激诱导ts 1感染的星形胶质细胞的氧化性凋亡，并鉴定预防这些事件的方法; 2）确定未感染的神经元在培养物和感染动物的脑中被邻近的tsl感染的星形胶质细胞间接杀死的机制，并确定预防这些事件的方法，和3）确定gPr 80 ENV积累是否引起ER/线粒体应激，导致感染动物的T细胞中的氧化应激，如在感染的星形胶质细胞中那样，并鉴定预防这些事件的方法。

DESCRIPTION (provided by applicant): A major goal of our research is to understand the pathogenic mechanisms involved in retrovirus-induced cell death in the nervous and immune systems using a mutant of MoMuLV-TB virus called ts 1. ts 1 infected mice typically exhibit selective depletion of T cells and neurons, and the disease that results resembles human AIDS. Like HIV, ts 1 appears to destroy T cells directly but neurons indirectly. The latter is likely due to loss of glial redox support and by release of oxidants, neurotoxins (e.g. glutamate) and proinflammatory cytokines from infected glial cells. Until recently, we have understood very little about what leads to the loss of neurons and T cells after HIV or ts 1 infection. What we do know is that a single mutation in the ts 1 env gene results in accumulation of tsl gPr80ENV in the endoplasmic reticulum (ER) in infected cells, and that this abnormality is responsible for immunodeficiency and neurodegeneration in infected animals. ts 1 infects a number of cell types, but only in infected T cells and astrocytes is the transport of gPr80ENV-inefficient, resulting in accumulation of gPr80ENV in the ER. For this reason, work in our laboratory has been focused on the effects of ts 1 infection on these two cell types. We now know that this cell type-specific abnormal viral protein accumulation (at least in astrocytes) plays a critical role in the selective induction of apoptosis in these cells. In view of the several similarities between ts 1-induced and HIV-induced disease, it is interesting to note that recent studies by others now suggest a similar relationship between the retention of gp 160 in the ER and the cytopathic effects of HIV infection in CD4+ T cells. Our central hypotheses are that the ER is the primary site where ts 1 gPr80ENV-mediated apoptotic effects are initiated, and that the failure of tsl gPr80ENV to move out of the ER activates the ER overload response (EOR) and the unfolded protein response (UPR), with a subsequent calcium overload-induced mitochondrial stress, and with overproduction of reactive oxygen species and loss of glutathione in infected astrocytes, leading to death of astrocytes and T cells. With loss of thiol redox support from astrocytes and release of oxidants and neurotoxins from infected astrocytes, neuronal death is the end result. We propose now to determine whether the above hypotheses are correct, to determine how astrocytes kill neurons and to ascertain whether T cell death induced by ts 1 also involves gPr80ENV accumulation and oxidant stress. More important, we hope that the knowledge we gain from these studies will allow us to identify ways to prevent these events. Our Specific Aims are: 1) To confirm that gPr80ENV accumulation, with resultant ER stress and mitochondrial stress induces oxidative apoptosis of ts 1-infected astrocytes, and to identify ways to prevent these events; 2) To determine the mechanisms by which uninfected neurons are indirectly killed by adjacent tsl-infected astrocytes in culture and in the brains of infected animals, and to identify ways to prevent these events, and 3) to determine whether gPr80ENV accumulation causes ER/mitochondrial stress leading to oxidant stress in T cells of infected animals, as it is in infected astrocytes, and to identify ways to prevent these events.