Tat Interaction with LRP and Its Role in AIDS Dementia

描述(申请人提供)：HIV-1感染中枢神经系统在大多数艾滋病患者中发生，并导致各种神经功能障碍和神经病理。小胶质细胞/巨噬细胞是I-IIV-I感染的主要靶细胞。人们普遍认为，艾滋病毒阳性者大脑中受影响最大的神经元很少感染艾滋病毒-1。因此，许多间接机制被提出与艾滋病相关的神经发病机制。其中包括可溶性病毒蛋白Tat。我们最近发现HIV-1Tat蛋白与低密度蛋白受体相关蛋白(LRP)相互作用，导致神经元摄取Tat蛋白。此外，TAT与LRP的相互作用导致LRP生理但神经毒性的配体在细胞外积累，这表明艾滋病相关的神经病理和其他神经退行性疾病，如阿尔茨海默病，可能共享一条最终导致痴呆的共同途径。我们的初步研究表明，在多西环素(Dox)调节的、脑靶向TAT转基因小鼠的大脑中，TAT的表达导致了神经病理，这与艾滋病患者的大脑中发现的类似。这一提议的基本假设是，TAT与LRP的相互作用有助于艾滋病相关的神经病理疾病，包括痴呆症。我们认为HIV-1Tat蛋白是导致HIV相关神经病理的主要神经致病因子。为了验证这一假说，我们提出了以下相关的具体目标：1)通过LRP摄取TAT来确定基因的表达；2)确定LRP介导的由TAT结合的细胞内信号；以及3)确定TAT诱导的神经病理机制。实验方法包括使用原代培养的小鼠皮质神经元，表达TAT的稳定细胞系，以及Dox调控的脑靶向TAT转基因小鼠模型。这种分子、细胞、生化和遗传学相结合的方法将使我们更好和独特地了解HIV-1Tat蛋白及其在HIV-L诱导的神经元损伤和艾滋病患者神经症状中的作用。此外，这些研究还将为开发抗艾滋病毒治疗策略提供新的线索，以治疗大多数艾滋病患者发生的艾滋病毒相关神经疾病。

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.