Mechanism of HIV-1 Tat Potentiation of Methamphetamine Neurotoxicity

描述(由申请人提供)： 在中枢神经系统中，基底节结构极易感染人类免疫缺陷病毒-1(HIV)。参与病毒复制的HIV-1蛋白TAT在神经元损伤中也发挥着重要作用，并概括了HIV-1感染脑部的许多病理变化。HIV-1感染患者经常滥用甲基苯丙胺等药物，众所周知，这种药物也会导致基底节的长期结构和功能变化。我们实验室以前的研究已经证明，Tat蛋白和甲基苯丙胺相互作用，对基底节多巴胺能神经递质系统造成严重的损害。尽管我们早期的研究涉及到活性氧和细胞因子TNF-1，但我们的初步数据强烈表明，神经酰胺诱导的囊泡单胺转运体的改变可能在TAT暴露后MA的毒性增强中起重要作用。在这个提案中，我们将在特定的目标1中确定HIV-1 TAT是否改变了突触终末DA的区划。在特定的目标2中，我们将调查第二信使神经酰胺的产生是否参与了TAT诱导的多巴胺区域化的变化。最后，在具体目标3中，我们将确定神经酰胺是否介导TAT和甲基苯丙胺之间的协同作用。对神经酰胺合成的药理和遗传抑制都将继续进行。在研究这些相互作用时，我们将检测1)囊泡单胺转运体功能，2)多巴胺释放(囊泡和组织)，3)多巴胺末端完整性和4)行为测量。这些实验的结果将阐明神经酰胺信号在多巴胺能功能障碍中的新作用，不仅在HIV-1中，而且在与帕金森病相关的神经元损伤中。

DESCRIPTION (provided by applicant): In the central nervous system, basal ganglia structures are highly susceptible to infection with the human immunodeficiency virus-1 (HIV). The HIV-1 protein, Tat, which is involved in viral replication, also plays an important role in the neuronal injury and recapitulates much the pathology seen in HIV-1 infection of the brain. Patients with HIV-1 infection often abuse drugs such as methamphetamine, a drug that is well known to also cause long-term structural and functional changes of the basal ganglia. Previous studies from our laboratory have demonstrated that Tat protein and methamphetamine interacted synergistically to cause profound damage to the basal ganglia dopaminergic neurotransmitter system. Although our earlier studies implicated reactive oxygen species and the cytokine TNF-1, our preliminary data strongly suggest that ceramide-induced alterations of the vesicular monoamine transporter may play a prominent role in the enhanced toxicity of MA seen after exposure to Tat. In this proposal, we will in Specific Aim 1, determine whether HIV-1 Tat alters the compartmentalization of DA in the synaptic terminal. In Specific Aim 2, we will investigate whether the production of the second messenger ceramide is involved in Tat-induced changes in dopamine compartmentalization. Lastly, in Specific Aim 3, we will determine whether ceramide mediates the synergism between Tat and methamphetamine. Both pharmacological and genetic inhibition of ceramide synthesis will be pursued. In studying these interactions, we will examine 1) vesicular mononamine transporter function, 2) dopamine release (vesicular and tissue) 3) dopamine terminal integrity and 4) behavioral measures. The results of these experiments will elucidate a novel role for ceramide signaling in dopaminergic dysfunction, not only in HIV-1, but also in the neuronal injury associated with Parkinson's disease.