HIV modulation of BAG3 impacting quality control of Tau in neuronal cells

HIV 对 BAG3 的调节影响神经元细胞中 Tau 的质量控制

• 批准号: 9922215
• 负责人: Kamel Khalili
• 金额: $ 39.63万
• 依托单位: TEMPLE UNIV OF THE COMMONWEALTH
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-30 至 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9922215
• 关键词: Affect; Alzheimer' s Disease; Alzheimer' s disease brain; Animal Model; Animals; Apoptosis; Attention; Autophagocytosis; BAG3 gene; Biochemical; Bioenergetics; Brain; CRISPR/Cas technology; Calcium Signaling; Cause of Death; Cell Culture Techniques; Cell physiology; Cells; Clinical Research; Clustered Regularly Interspaced Short Palindromic Repeats; Data; Deposition; Development; Disease; Down-Regulation; Energy Metabolism; Ensure; Environment; Equilibrium; Event; Excision; Generations; Genome; HIV; HIV Infections; HIV Seronegativity; HIV Seropositivity; HIV tat Protein; HIV-1; HIV-associated neurocognitive disorder; Heat-Shock Proteins 70; Homeostasis; In Vitro; Infection; Interruption; Investigation; Laboratories; Life; Light; Mediating; Membrane Potentials; Memory; Microelectrodes; Microtubule-Associated Proteins; Microtubules; Mitochondria; Modeling; Molecular; Molecular Chaperones; Neurodegenerative Disorders; Neurofibrillary Tangles; Neurons; Organelles; Outcome; Outcome Study; Pathogenesis; Pathogenicity; Pathway interactions; Patients; Physiological; Process; Production; Proteins; Quality Control; Risk; Risk Factors; Role; Signal Transduction; Stress; Stress-Induced Protein; System; Thinking; Toxic effect; Transgenic Animals; United States; Up-Regulation; Viral Proteins; Virus; aging brain; antiretroviral therapy; brain tissue; endoplasmic reticulum stress; experimental study; human old age (65+); in vivo; interest; misfolded protein; mitochondrial membrane; mutant; neuron loss; neuronal circuitry; neurotoxic; parkin gene/protein; premature; protein aggregation; proteostasis; small hairpin RNA; tat Protein; tau Proteins; tau aggregation; tau phosphorylation; tau-1; transmission process; treatment effect

PROJECT SUMMARY It is estimated that more than 10% of the 1.1 million HIV positive patients in United States will be over 65 years old in less than ten years, a critical stage in life where the the risk for developing Alzheimer’s disease (AD) increases. Earlier results from clinical studies showed several abnormalities including difficulties with memory, thinking, and reasoning become more common in older HIV positive patients, implying that their risk factors may be elevated when compared with their HIV negative counterparts. This notion brings up the concept that HIV infection, even in patients whose virus is well controlled by antiretroviral therapy (ART), may be more prone to developing neurodegenerative disorders including AD. Considering the inability of ART to effectively suppress expression of viral proteins, including HIV Tat, which is a profoundly neurotoxic protein, we envision a scenario in which, by dysregulating the protein quality control (PQC) pathway, Tat may perturb homeostasis of key proteins associated with the pathogenesis of AD and set the stage for the development of disease. Several data from our and other laboratories support this concept. First, we demonstrated that Tat inhibits expression of BAG3, a co-chaperone/partner of HSP70 that is involved in the removal of dysfunctional and obsolete organelles including mitochondria through a process called mitophagy, and participates in autophagy and clearance of damaged and misfolded proteins by the protein quality control (PQC) pathway. Second, activation of BAG3 is concurrent with a decrease in the level of phosph-tau and an increase in the clearance of tau in neuronal cells. Third, soon after destabilization of microtubules, tau associates with Hsp70/Hsc70, a key partner of BAG3. Fourth, induction of Tat in the brains of transgenic animals increases accumulation of phospho-tau. Thus, Tat- mediated reduction in the level of BAG3 may have a damaging effect on neuronal cells by interrupting the process that ensures intracellular removal of the toxic from of tau, yet maintains the healthy species of tau that is critical for neuronal cell function. Hyper-phosphorylation of tau, which contributes to its misfolding and toxicity, may be attributed to Tat via induction of ROS, ER stress, and mitochondrial dysfunctionality. The latter is of particular interest as truncated tau has been implicated in dysregulation of mitochondrial dynamics and healty energy metabolism. These observations prompted us to hypothesize that, on one hand, Tat impacts the quality and concentration of proper levels of functional tau and the clearance of its toxic form by suppressing expression of BAG3, and on the other hand, Tat contributes to the generation of the toxic tau and dysfunctionality of bioenergetic pathways and mitochondria by inducing stress conditions in cells. To examine this model, we will employ in vitro primary neuronal cultures, ex vivo animal brain tissue, and an in vivo animal model to unravel the underlying molecular basis of HIV-1/Tat-induced perturbation of PQC and homeostasis of tau in neuronal cell function.

项目摘要 据估计，美国110万艾滋病毒阳性患者中有10%以上将超过65岁 在不到十年的时间里就变老了，这是生命中的一个关键阶段， 增大早期的临床研究结果显示了几种异常，包括记忆困难， 思考和推理在老年艾滋病毒阳性患者中变得更加普遍，这意味着他们的风险因素可能 与艾滋病毒阴性者相比，其感染率有所上升。这个概念提出了一个概念， 感染，即使在病毒通过抗逆转录病毒疗法（ART）得到很好控制的患者中， 发展成神经退行性疾病，包括AD。考虑到ART无法有效抑制 表达病毒蛋白，包括HIV达特，这是一个深刻的神经毒性蛋白，我们设想一个场景 其中，通过蛋白质质量控制（PQC）途径的失调，达特可能扰乱关键的 与AD发病机制相关的蛋白质，并为疾病的发展奠定基础。几个数据 我们的实验室和其他实验室都支持这一概念。首先，我们证明了达特抑制BAG 3的表达， 一种参与清除功能失调和过时细胞器的HSP 70的共同伴侣/伴侣 包括线粒体通过一个过程称为线粒体自噬，并参与自噬和清除 通过蛋白质质量控制（PQC）途径破坏和错误折叠的蛋白质。第二，BAG 3的激活是 同时神经元细胞中磷酸化-tau水平降低和tau清除率增加。 第三，在微管不稳定后不久，tau与BAG 3的关键伙伴Hsp 70/Hsc 70相关联。 第四，转基因动物脑中达特的诱导增加了磷酸化tau的积累。因此，达特- 介导的BAG 3水平的降低可能通过中断神经元细胞的生长而对神经元细胞产生损伤作用。 这一过程确保细胞内去除有毒的tau，但仍保持健康的tau种类， 对神经细胞功能至关重要tau蛋白的过度磷酸化导致其错误折叠和毒性， 可能归因于达特通过诱导ROS、ER应激和线粒体功能障碍。后者是 特别令人感兴趣的是，截短的tau蛋白与线粒体动力学和健康的失调有关。 能量代谢这些观察促使我们假设，一方面，达特影响质量 以及适当水平的功能性tau的浓度和通过抑制表达清除其毒性形式 而另一方面，达特有助于产生毒性tau蛋白和BAG 3的功能障碍。 生物能途径和线粒体通过诱导细胞应激条件。为了检验这个模型，我们将 使用体外原代神经元培养物、离体动物脑组织和体内动物模型来阐明神经元的功能。 HIV-1/Tat诱导神经细胞PQC和tau蛋白稳态紊乱的分子基础 功能