Tat Interaction with LRP and Its Role in AIDS Dementia

描述（由申请人提供）：HIV-1中枢神经系统感染在大多数艾滋病患者中发生，并引起各种神经功能障碍和神经病理。小胶质细胞/巨噬细胞是i - iv - i感染的主要靶细胞。人们普遍认为，hiv阳性个体大脑中受影响最大的神经元很少被HIV-1感染。因此，人们提出了一些与艾滋病相关的神经发病机制的间接机制。其中包括可溶性病毒蛋白Tat。我们最近发现HIV-1 Tat蛋白与低密度蛋白受体相关蛋白（LRP）相互作用并导致Tat蛋白的神经元摄取。此外，与LRP的相互作用导致LRP生理但神经毒性配体的细胞外积累，这表明艾滋病相关的神经病理学和其他神经退行性疾病（如阿尔茨海默病）可能具有最终导致痴呆的共同途径。我们的初步研究表明，多西环素（Dox）调控的Tat在大脑中的表达，大脑靶向Tat转基因小鼠导致神经病变，让人想起艾滋病患者的大脑中注意到的那些。这一提议的潜在假设是，Tat与LRP的相互作用有助于艾滋病相关的神经病理疾病，包括痴呆。我们认为HIV-1 Tat蛋白是导致hiv相关神经病理的主要神经致病因子。为了验证这一假设，我们提出了以下相关的具体目标：1)通过lrp摄取Tat来确定基因表达；2)确定lrp介导的Tat结合引发的细胞内信号传导；3)确定tat诱导的神经病理机制。实验方法包括使用原代小鼠皮质神经元培养，表达Tat的稳定细胞系，以及dox调节的脑靶向Tat转基因小鼠模型。这种结合分子、细胞、生化和遗传的方法将提供对高度重要和普遍存在的HIV-1 Tat蛋白的更好和独特的理解，以及它在HIV-1诱导的神经元损伤和艾滋病患者神经系统症状中的作用。此外，这些研究还将为开发抗hiv治疗策略提供新的线索，以治疗大多数艾滋病患者中发生的hiv相关神经系统疾病。

DESCRIPTION (provided by applicant): HIV-1 infection of the central nervous system occurs in a majority of AIDS patients, and causes a variety of neurologic dysfunction and neuropathologies. Microglia/macrophages are the major target cells for I-IIV-I infection. It has generally been accepted that neurons that are mostly affected in the brain of HIV-positive individuals are rarely infected by HIV-1. Therefore, a number of indirect mechanisms have been proposed for AIDS-associated neuropathogenesis. Among these is the soluble viral protein Tat. We have recently shown that HIV-1 Tat protein interacts with low-density protein receptor-related protein (LRP) and results in neuronal uptake of Tat protein. Moreover, Tat interaction with LRP leads to extracellular accumulation of LRP physiological but neurotoxic ligands, suggesting that AIDS-associated neuropathology and other neurodegenerative diseases such as Alzheimer's disease, may share a common pathway that eventually leads to dementia. Our preliminary studies demonstrated that Tat expression in the brain of doxycycline (Dox)-regulated, brain-targeted Tat transgenic mice results in neuropathologies, reminiscent of those noted in the brain of AIDS patients. The underlying hypothesis for this proposal is that Tat interaction with LRP contributes to AIDS-associated neuropathological disorders including dementia. We propose that HIV-1 Tat protein is a major neuropathogenic factor contributing to HIV-associated neuropathology. To test this hypothesis, we propose the following interrelated specific aims: 1) To determine gene expression by LRP-uptaken Tat; 2) To determine LRP-mediated intracellular signaling elicited by Tat binding; and 3) To determine mechanisms of Tat-induced neuropathology. Experimental approaches include use of the primary mouse cortical neuron cultures, Tat-expressing stable cell lines, and the Dox-regulated, brain-targeted Tat transgenic mouse model. This combined molecular, cellular, biochemical, and genetic approach will provide a better and unique understanding of the highly important and pervasive HIV-1 Tat protein, and its role in HIV-l-induced neuronal injury and neurologic symptoms of AIDS patients. In addition, these studies will also yield new clues for developing anti-HIV therapeutic strategies for treating HIV-associated neurological disorders occurring in the majority of AIDS patients.