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.

项目总结 据估计，在美国110万艾滋病毒阳性患者中，超过10%的人将超过65岁 在不到十年的时间里变老，这是人生中一个关键阶段，在这个阶段，患阿尔茨海默病(AD)的风险很大 增加。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HIV阳性患者中变得更加常见，这意味着他们的风险因素可能 与艾滋病毒阴性的同龄人相比，这一比例有所提高。这一概念提出了艾滋病毒的概念 感染，即使在病毒被抗逆转录病毒疗法(ART)很好地控制的患者中，可能更容易发生 出现包括阿尔茨海默病在内的神经退行性疾病。考虑到ART无法有效地压制 病毒蛋白的表达，包括HIV Tat，这是一种深刻的神经毒性蛋白，我们设想了一个场景 其中，通过蛋白质质量控制(PQC)途径的失调，TAT可能扰乱KEY的动态平衡。 与阿尔茨海默病发病相关的蛋白质，为疾病的发展奠定基础。几个数据 来自我们和其他实验室的专家支持这一概念。首先，我们证明了TAT抑制BAG3的表达， HSP70的辅助伴侣/伴侣，参与功能失调和陈旧细胞器的移除 包括线粒体，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蛋白质。第二，BAG3的激活是 同时神经细胞内磷酸化tau蛋白水平下降，tau蛋白清除率增加。 第三，在微管失稳后不久，tau与BAG3的关键合作伙伴Hsp70/Hsc70联系在一起。 第四，转基因动物大脑中TAT的诱导增加了磷酸-tau的积累。因此，TAT- 介导的BAG3水平的降低可能通过阻断BAG3的表达而对神经细胞产生损伤作用 确保从tau的细胞内去除有毒物质的过程，同时保持tau的健康物种 对神经细胞功能至关重要。Tau的过度磷酸化，导致其错误折叠和毒性， 这可能归因于TAT通过诱导ROS、内质网应激和线粒体功能障碍。后者是 特别感兴趣的是，截短的tau与线粒体动力学和健康的失调有关 能量代谢。这些观察结果促使我们假设，一方面，TAT会影响质量 和适当水平的功能tau的浓度以及通过抑制表达来清除其毒性形式 另一方面，TAT促进了有毒tau的产生和BAG3的功能障碍 通过在细胞中诱导应激条件的生物能量途径和线粒体。为了检验这个模型，我们将 采用体外原代神经元培养、体外动物脑组织和体内动物模型来解开 HIV-1/Tat诱导神经细胞PQC紊乱和tau蛋白稳态的分子基础 功能。