Cellular and molecular mechanisms of gp120 neurotoxicity

gp120神经毒性的细胞和分子机制

基本信息

批准号：
8263182
负责人：
Italo Mocchetti
金额：
$ 23.25万
依托单位：
GEORGETOWN UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-09-30 至 2013-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8263182
关键词：
AIDS Dementia Complex Affect Apoptosis Apoptotic Axon Axonal Transport Back Behavioral Binding Biochemical Brain CXCR4 Receptors CXCR4 gene Cells Cytoplasmic Organelle Cytoskeleton Data Dementia Development Disease Dynein ATPase Endocytosis Endosomes Event Exhibits Functional disorder Glycoproteins Goals HIV HIV Envelope Protein gp120 HIV-1 Impaired cognition In Vitro Individual Infection Inflammatory Inflammatory Response Injury Invaded Investigation Kinesin Knowledge Lead Length Lysosomes Maintenance Mediating Membrane Microtubule-Associated Proteins Microtubules Mitochondria Molecular Motor Mus Nature Nerve Degeneration Neuraxis Neurodegenerative Disorders Neurologic Neurons Neurotoxins Organelles Pathology Pathway interactions Pattern Phosphorylation Phosphotransferases Physiological Play Process Proteins Rattus Rodent Role Series Signal Pathway Site Sorting - Cell Movement Spinal Ganglia Staging Survival Rate Symptoms Synapses Testing Time Toxic effect Tubulin Vascularization Viral Envelope Proteins Viral Proteins Virus axonal degeneration base caspase-3 chemokine receptor cytokine design effective therapy env Gene Products fast axonal transport immunoreactivity in vivo inhibitor/antagonist injured neuron apoptosis neuron loss neuronal cell body neuronal survival neurotoxic neurotoxicity overexpression postsynaptic presynaptic prevent protein expression receptor research study tau Proteins

项目摘要

DESCRIPTION (provided by applicant): Axonal injury is seen in subjects with Human Immunodeficiency Virus type 1 (HIV) associated dementia (HAD). The lack of documented evidence of direct infection of neurons by HIV has prompted studies to reveal possible mechanisms for HIV-mediated axonal damage. However, the nature and the site of initial injury to the neuron are unknown; in particular it is unclear if the process starts in the axons itself or in the neuronal cell body. Several lines of independent investigations have shown that the viral envelope protein gp120 promotes neuronal degeneration. The neurotoxic effect of gp120 occurs through chemokine receptors. Preliminary evidence has shown that the chemokine receptor CXCR4 promotes endocytosis of T-tropic gp120 into neurons. Endocytosis of gp120 is followed by axonal transport through microtubules. The length of axons and survival rate of neurons that do not internalize gp120 is significantly greater when compared to those accumulating gp120. Moreover, agents that block axonal transport are neuroprotective against gp120 even in the presence of cytokines, suggesting that the toxic effect of gp120 may not necessarily require an inflammatory response. Most importantly, gp120 endocytosis and transport precede synaptic simplification and caspase-3 activation and therefore neuronal cell death, suggesting that accumulation and axonal transport of gp120 are crucial to its toxicity. These data lead to a new challenging hypothesis that gp120 binding to CXCR4 receptor initiates a series of events that triggers direct axonal toxicity. However, little is known about the cellular and molecular mechanisms of this effect. Internalized gp120 could cause axonal damage and neuronal apoptosis by affecting axonal proteins or impairing the axonal transport of important molecules that are necessary for neuronal survival and maintenance. The experiments planned in this project will examine whether gp120 affects selected regulatory kinases of axonal transport, or microtubule-associated protein such as Tau, or other cytoskeleton proteins that when impaired, promote the "dying-back" pattern of degeneration. These experiments will be accompanied by histological analysis of gp120 immunoreactivity within endosomes or other cellular organelles, as well as by biochemical analyses of pro-inflammatory cytokines. The ability of gp120 to induce a rapid axonal/dendritic degeneration raises the hypothesis that this protein is sufficient to initiate an irreversible neurodegenerative process even in the absence of other endogenous neurotoxins or other patho-physiological insults. If proven, our hypothesis that gp120 injures neurons by being internalized and transported to their cell bodies will lead to a major discovery in this field. Overall, we expect to provide new significant data that help in the design of adjunct therapies against synaptic simplifications caused by HIV. PUBLIC HEALTH RELEVANCE: Human Immunodeficiency Virus invades the brain and causes degeneration of neurons. Currently, there is no effective therapy to reverse HIV-mediated neuronal degeneration. Key to develop new therapies is the understanding of the mechanisms of HIV neurotoxicity. In this proposal, we will test the hypothesis that the virus promotes degeneration of axons through its envelope protein gp120. This viral protein is internalized into neurons and transported to cell bodies. Neurons internalizing gp120 exhibit short processes and apoptosis. These phenomena are blocked by inhibitors of axonal transport. Therefore, we propose to explore the hypothesis that axonal transport of gp120 is an intracellular mechanism crucial for its neurotoxic effect.

描述（由申请人提供）：在患有人类免疫缺陷病毒1型（HIV）相关痴呆（HAD）的受试者中，轴突损伤可见。缺乏艾滋病毒直接感染神经元的证据，促使研究揭示了HIV介导的轴突损伤的可能机制。但是，神经元的初始损伤的性质和部位尚不清楚。特别是目前尚不清楚该过程是在轴突本身还是在神经元细胞体中开始的。几条独立研究表明，病毒包膜蛋白GP120促进了神经元变性。 GP120的神经毒性作用是通过趋化因子受体发生的。初步证据表明，趋化因子受体CXCR4可促进T-Tropic GP120在神经元中的内吞作用。 GP120的内吞作用，然后是通过微管的轴突运输。与累积GP120的轴突的长度和未内化GP120的神经元的存活率明显更大。此外，即使在存在细胞因子的情况下，封闭轴突转运的药物也对GP120具有神经保护作用，这表明GP120的毒性作用不一定需要炎症反应。最重要的是，GP120内吞和转运先于突触简化和caspase-3激活，因此是神经元细胞死亡，这表明GP120的积累和轴突运输对其毒性至关重要。这些数据导致了一个新的具有挑战性的假设，即GP120与CXCR4受体的结合启动了一系列触发直接轴突毒性的事件。然而，对于这种作用的细胞和分子机制知之甚少。内部化的GP120可能会通过影响轴突蛋白或损害神经元存活和维持所需的重要分子的轴突转运而引起轴突损伤和神经元细胞凋亡。该项目中计划的实验将检查GP120是否会影响轴突转运的选定调节激酶，还是微管相关的蛋白（例如Tau），或其他细胞骨架蛋白，而当受损时，这些蛋白会促进“垂死的”模式。这些实验将伴有内体或其他细胞细胞器内GP120免疫反应性的组织学分析，以及对促炎性细胞因子的生化分析。 GP120诱导快速轴突/树突变性的能力提出了这样的假设，即即使没有其他内源性神经毒素或其他致病生理学侮辱，该蛋白也足以引发不可逆的神经退行性过程。如果被证明，我们的假设是GP120通过内在化并将其运输到细胞体内会损害神经元，这将导致该领域的重大发现。总体而言，我们希望提供新的重要数据，以帮助设计辅助疗法，以防止艾滋病毒引起的突触简化。公共卫生相关性：人免疫缺陷病毒侵入大脑并引起神经元的变性。当前，尚无有效的疗法来逆转HIV介导的神经元变性。开发新疗法的关键是对HIV神经毒性机制的理解。在此提案中，我们将检验以下假设：病毒通过其包膜蛋白GP120促进轴突的变性。该病毒蛋白被内化为神经元并运输到细胞体中。神经元内部化GP120表现出短暂的过程和凋亡。这些现象被轴突运输的抑制剂阻塞。因此，我们建议探讨以下假设：GP120的轴突转运是其神经毒性作用至关重要的细胞内机制。