HIV interaction with drugs of abuse and adult neurogenesis

描述（由申请人提供）：这是一份响应PAR-09-222题为“前沿基础研究奖（CEBRA）”的R21申请。这项I期CEBRA应用的主要目标是创建和表征一种新的小鼠模型，用于研究HIV感染和药物滥用对成人神经发生的综合影响。在整个成年期，侧脑室的室下区和齿状回（DG）的颗粒下区都有活跃的神经发生；后者在海马体中产生颗粒细胞，这些颗粒细胞与神经认知功能有关，并受到药物滥用和艾滋病毒感染等病理刺激的负调节。众所周知，滥用药物包括阿片类药物、可卡因和甲基苯丙胺（冰毒）会抑制成人神经发生。相比之下，人们对HIV感染对成人神经发生的影响、病毒决定因素以及潜在的细胞和分子机制知之甚少。此外，关于HIV感染和药物滥用对成人神经发生的综合影响的信息很少。我们最近建立了一个多西环素（Dox）诱导的脑特异性HIV-1 Tat双基因小鼠模型（iTat），在该模型中，Tat的表达可以被诱导在大脑中完全表达，并且我们已经证明，在没有HIV-1感染的情况下，Tat蛋白在大脑中的表达足以诱导神经行为和神经病理，这些神经行为和神经病理概括了HIV-1感染个体大脑中的一些重要特征（Kim等人，Am）。[j] .环境科学与技术，2003(2)。我们的研究表明Tat对成人神经发生有潜在的抑制作用。该项目的总体假设是，HIV病毒与滥用药物相互作用，导致HIV感染成人神经发生减少，并导致这些个体的神经认知功能障碍。为了验证这一假设，在I期CEBRA提案中，我们建议通过将iTat基因小鼠与巢蛋白GFP转基因小鼠杂交，建立可诱导的脑特异性Tat/神经元祖细胞（NPC）特异性巢蛋白启动子驱动的GFP小鼠模型（iTat/巢蛋白GFP）。通过对暴露于甲基甲醚和表达甲基甲醚的iTat/ nesting - gfp小鼠中鼻咽癌的时空分布、分化和存活特征的表征，为研究Tat效应和Tat/METH联合作用对成体神经发生的影响提供了独特的机会；功能后果将与这些小鼠的神经认知功能相关。完成这些研究将使我们能够确定II期Tat/ meth改变神经发生的细胞和分子机制，我们相信这将最终有助于确定促进新生神经发生的治疗方法（分子），以功能性替代HIV介导的神经变性，预防、改善或逆转HIV感染者和HIV感染的药物滥用者的HIV相关痴呆或轻度认知和运动障碍的并发症。

DESCRIPTION (provided by applicant): This is a R21 application in response to PAR-09-222 entitled "Cutting-Edge Basic Research Award (CEBRA)". The main goal of this Phase I CEBRA application is to create and characterize a novel mouse model for studies on the combined impact of HIV infection and drug abuse on adult neurogenesis. Active neurogenesis continues throughout adulthood in both the subventricular zone of the lateral ventricle and the subgranular zone of the dentate gyrus (DG); the latter gives rise to granule cells in the hippocampus, which has been linked to neurocognitive function and is negatively regulated by pathological stimuli such as drug abuse and HIV infection. It is well established that drugs of abuse including opiates, cocaine, and methamphetamine (METH) inhibit adult neurogenesis. In contrast, not much is known about the effects of HIV infection on adult neurogenesis, the responsible viral determinants and the underlying cellular and molecular mechanisms. Furthermore, there is scant information about the combined impact of HIV infection and drug abuse on adult neurogenesis. We have recently established an doxycycline (Dox)-inducible brain-specific HIV-1 Tat bigenic mouse model (iTat) in which Tat expression can be induced to exclusively express in the brain, and we have demonstrated that expression of Tat protein in the brain in the absence of HIV-1 infection is sufficient to induce neurobehavioral and neuropathologies that recapitulate some important features in the brain of HIV-1-infected individuals (Kim et al., Am. J. Path, 162:1693-707, 2003). Our studies suggest a potential inhibitory role of Tat on adult neurogenesis. The overall hypothesis of this project is that HIV Tat interacts with drugs of abuse, leading to decreased neurogenesis in HIV-infected adults and contributing to the neurocognitive dysfunction in these individuals. To test this hypothesis, in this Phase I CEBRA proposal, we propose to create an inducible brain-specific Tat/neuron progenitor cells (NPC)-specific nestin promoter-driven GFP mouse model (iTat/nestin-GFP) by breeding the iTat bigenic mice with nestin-GFP transgenic mice. Direct, convenient and reproducible visualization and tracking of NPC in this new model will provide a unique opportunity for us to study Tat effects and Tat/METH combined effects on adult neurogenesis through characterization of the temporal and spatial distribution, differentiation and survival of NPC in METH-exposed and Tat-expressing iTat/nestin-GFP mice; the functional consequences will be correlated with the neurocognitive function of these mice. Completing the studies will allow us to define the cellular and molecular mechanisms responsible for Tat/METH-altered neurogenesis at Phase II, which we believe will eventually help identify therapeutic approaches (molecules) that promote de novo neurogenesis for functional replacement of HIV-mediated neurodegeneration and prevent, ameliorate, or reverse the complications of HIV- associated dementia or mild cognitive and motor disorders of HIV-infected individuals and HIV-infected drug abusers. PUBLIC HEALTH RELEVANCE: The HIV/AIDS epidemic has posed a great social, economic and political challenge in the 21st century. As of December 2008, 34.0 million adults and 2.1 million children are estimated to have acquired HIV infection worldwide. HIV infection of the brain occurs early in the course of infection and often leads to cognitive, motor, and other behavioral problems. In the era of highly active antiretroviral therapy, a milder form of HIV-associated dementia so-called minor cognitive and motor disorder has become predominant and prevalent among the HIV-infected population. While our understanding of the disease mechanisms remains incomplete, there are no effective therapies to reduce, prevent, or reverse HIV-mediated cognitive, motor and behavioral problems at the present time. On the other hand, HIV infection and drug abuse are interlinked epidemics throughout the world, while each alone is capable of causing cognitive deficits. In this current study, we propose to create a novel mouse model for studies on the connection between HIV infection, drug abuse and cognitive dysfunction. This model shall eventually lead to development of therapeutic strategies to restore the normal cognitive function of HIV-infected individuals and HIV-infected drug abusers.