Control of Retrovirus CNS Disease by redox modulation

描述（由申请人提供）：人类免疫缺陷病毒（HIV）介导的中枢神经系统（CMS）细胞死亡的机制尚不明确，但有证据表明氧化应激在HIV相关痴呆（HAD）的神经发病机制中起关键作用。目前已经建立了几种HAD小鼠模型，但很少有适合研究HAD中氧化应激和细胞死亡途径的模型。在我们的HAD模型中，FVB/N小鼠感染了Moloney小鼠白血病病毒的突变体，称为te1，它会导致进行性神经免疫变性，在许多方面与HAD相似。与HAD一样，神经胶质细胞被te1感染，但神经元没有，尽管神经元丢失是CMS中最严重的病理特征。我们实验室的工作重点是氧化应激在te1感染星形胶质细胞死亡中的作用，以及通过抗氧化治疗预防神经变性（ND）。我们假设te1介导的氧化应激导致星形胶质细胞功能障碍，功能障碍的星形胶质细胞无法支持附近的神经元，从而导致神经元死亡。为了支持这一观点，我们已经证明了活性氧（ROS）在te1感染的星形胶质细胞中积累。在te1感染的星形胶质细胞和te1感染小鼠的中枢神经系统中，用抗氧化剂GVT （a-鲁米诺）治疗可减少ROS积累并防止细胞死亡。我们还发现，p53磷酸化发生在te1感染小鼠的星形胶质细胞和神经元中，这些细胞的死亡可能涉及p53依赖性细胞死亡途径的激活。此外，te1感染的星形细胞通过激活共济失调毛细血管扩张突变（ATM）、细胞外信号调节激酶（ERK）和哺乳动物雷帕霉素靶点（mTOR）来响应ROS的增加。所有这三种激酶都被证明能够使p53磷酸化。在te1感染的星形胶质细胞中，p53靶促凋亡因子PUMA、Bax和细胞周期抑制剂p21上调，抗凋亡因子Bcl-2和Bcl-xL降低。已知所有这些事件都发生在HAD中。我们假设类似的细胞死亡机制有助于te1相关的ND和HAD。因此，我们的目标是了解te1介导的ND中星形细胞功能障碍和神经元死亡的机制。我们将专注于三个具体目标：1)确定p53如何促进氧化应激；2)证实神经元通过星形胶质细胞共享的途径受到氧化应激的损害；3)确定抗氧化剂和硫醇补充剂是否对星形胶质细胞和神经元具有保护作用。我们的研究可能为HAD和其他与氧化应激、p53激活和线粒体死亡途径相关的神经退行性疾病的治疗找到新的靶点。

DESCRIPTION (provided by applicant): The mechanisms underlying human immunodeficiency virus (HIV)-mediated cell death in the central nervous system (CMS) are not well defined, but evidence suggests that oxidative stress plays a critical role in neuropathogenesis in HIV-associated dementia (HAD). Several mouse models of HAD have been developed, but few are suitable to the study of oxidative stress and cell death pathways in HAD. In our model of HAD, FVB/N mice are infected with a mutant of the Moloney murine leukemia virus, called te1, which causes progressive neuroimmunodegeneration that is in many ways similar to that of HAD. As in HAD, glial cells are infected by te1, but neurons are not, although neuronal loss is the most severe pathological feature in the CMS. Work in our lab has focused on the role of oxidative stress in the death of te1 -infected astrocytes, and on prevention of neurodegeneration (ND) via antioxidant treatment. We hypothesize that te1 -mediated oxidative stress causes astrocyte dysfunction, that dysfunctional astrocytes are unable to support nearby neurons, and that neurons die as a result. In support of this idea, we have demonstrated that reactive oxygen species (ROS) accumulate in te1-infected astrocytes. Treatment with an antioxidant called GVT (a-luminol) decreases ROS accumulation and prevents cell death in te1-infected astrocytes and in CNS of te1-infected mice. We have also shown that p53 phosphorylation occurs in astrocytes and neurons of te1 -infected mice, and that death of these cells may involve activation of p53-dependent cell death pathways. Further, te1- infected astrocytes respond to ROS increases via activation of ataxia telangiectasia mutated (ATM), extracellular signal-regulated kinases (ERK), and mammalian target of rapamycin (mTOR). All these three kinases have been shown to be able to phosphorylate p53. In te1 -infected astrocytes, the p53-target proapoptotic factors PUMA, Bax, and cell cycle inhibitor p21 are upregulated, and the antiapoptotic factors Bcl-2 and Bcl-xL decrease. All of these events are known to occur in HAD. We hypothesize that similar cell death mechanisms contribute to te1 -associated ND and HAD. Our goal is therefore to understand the mechanisms underlying astrocyte dysfunction and neuronal death in te1 -mediated ND. We will focus on three specific aims: 1) to determine how p53 contributes to oxidative stress; 2) to confirm that neurons are damaged by oxidative stress through pathways shared by astrocytes; and 3) to determine whether antioxidants and thiol-repleting agents provide protection for astrocytes and neurons. Our studies may identify new targets for treatment of HAD and of other neurodegenerative diseases associated with oxidative stress, p53 activation and the mitochondrial death pathway.