Sustained eIF5A hypusination at the core of brain metabolic dysfunction in TDP-43 proteinopathies

项目摘要/摘要 TAR DNA结合蛋白43(TDP-43)的病理与临床痴呆有关，并发生在更多的 超过一半的临床诊断为阿尔茨海默病(AD)的患者(1，2)。边缘主导型的发现 TDP-43脑病(晚期)强调与年龄相关的TDP-43蛋白病的重要性，伴有或 没有共病的AD病理特征。缺乏针对TDP-43病理的疾病修饰剂 迫切需要确定针对TDP-43蛋白病的新治疗途径。有趣的是， 葡萄糖摄取和利用的区域性中断与AD神经病理的进展有关(3-5)，以及 然而，关于TDP-43对患病大脑中葡萄糖和能量稳态的影响还没有达成共识(6)。 这项提案将通过研究eIF5A炒作的影响来解决这一重大的知识缺口 TDP-43病理学中大脑代谢状态的通路。EIF5A是一种起始/延伸因子，也是唯一 被激化的蛋白质(EIF5AHyp)。脱氧亚硫氨酸合成酶和脱氧亚精氨酸羟基酶 (DOHH)活性将单个赖氨酸转化为亚硫氨酸部分。我们的可行性数据发现，TDP-43病理在 AD脑和TDP-43小鼠模型可诱导DHS表达和亚硫氨酸水平。此外，我们还展示了 增强的低渗作用加剧TDP-43的病理，扰乱脑内葡萄糖稳态，并施加 线粒体生物能缺陷。我们的中心假设是，针对国土安全部的战略将减少 亚硫氨酸水平将通过恢复大脑葡萄糖代谢和改善TDP-43神经发病机制 线粒体生物能量学，认知衰退和神经退化的上游。在目标1中，我们将 建立TDP-43转基因小鼠成年前脑中DHS(DHSko)的条件性缺失 模型将通过纳米串分析影响大脑代谢转录图谱并确定生物学 定义eIF5AHyp-TDP-43表型的签名。我们还将利用CNS-Met代谢组学核心来 测量大脑代谢物水平，同时生化测定代谢蛋白、酶和TDP-43 病理学。我们将进一步阐明DHSko如何挽救LTP、认知能力和神经退行性变 与一种新的TDP-43动物模型的TDP-43表型相关。在目标2中，我们将定义eIF5AHyp的角色 神经元和星形胶质细胞反应神经元的线粒体生物能量学。我们将确定国土安全部如何 抑制作用挽救了线粒体生物能量学，并恢复了原代细胞的代谢平衡。我们还将 测定细胞和线粒体TDP-43蓄积及线粒体结构完整性。总体而言， 拟议的研究将提供证据表明，TDP-43表型中的eIF5AHyp途径位于 痴呆症的不可逆转阶段。它还提供了第一个详细的机制，说明如何减少亚硝胺的恢复 糖调节失调和线粒体功能障碍，维持神经-星形胶质细胞支持和健康神经元 活性，同时挽救TDP-43蛋白病动物模型的病理表型。

PROJECT SUMMARY/ ABSTRACT TAR DNA-binding protein 43 (TDP-43) pathology is associated with clinical dementia and occurs in more than half of clinically diagnosed Alzheimer’s disease (AD) patients (1, 2). The discovery of limbic-predominant TDP-43 encephalopathy (LATE) emphasized the importance of age-related TDP-43 proteinopathy, with or without co-morbid AD pathological hallmarks. The lack of disease-modifying agents against TDP-43 pathology creates an urgent need to identify novel therapeutic pathways against TDP-43 proteinopathy. Interestingly, regional disruption of glucose uptake and utilization is linked to the progression of AD neuropathology (3-5), and yet, there is no consensus on the effect of TDP-43 on glucose and energy homeostasis in the diseased brain (6). This proposal will address this significant gap in knowledge by studying the impact of the eIF5A hypusination pathway on the brain’s metabolic state in TDP-43 pathology. eIF5A is an initiation/elongation factor and the only protein undergoing hypusination (eIF5AHyp). Deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH) activity convert a single lysine to a hypusine moiety. Our feasibility data finds that TDP-43 pathology in AD brain and TDP-43 mouse models induces DHS expression and hypusine levels. Additionally, we show that enhanced hypusination exacerbates TDP-43 pathology, dysregulates brain glucose homeostasis and exerts mitochondrial bioenergetic defects. Our central hypothesis states that DHS-targeted strategies reducing hypusine levels will ameliorate TDP-43 neuropathogenesis by restoring brain glucose metabolism and mitochondrial bioenergetics, upstream of cognitive decline and neurodegeneration. In Aim 1, we will establish how conditional deletion of the DHS (DHSko) in the adult forebrain of the TDP-43 transgenic mouse model will affect the brain metabolic transcriptomic profile via NanoString analysis and determine biological signatures that define the eIF5AHyp - TDP-43 phenotype. We will also utilize the CNS-Met Metabolomics Core to measure brain metabolite levels, while biochemically determining metabolic proteins, enzymes, and TDP-43 pathology. We will further elucidate how DHSko can rescue LTP, cognitive performance, and neurodegeneration associated with TDP-43 phenotype of a novel TDP-43 animal model. In Aim 2, we will define the role of eIF5AHyp on the mitochondrial bioenergetics of neurons and astrocytic-responsive neurons. We will establish how DHS inhibition rescues mitochondrial bioenergetics and restores metabolite balance in primary cells. We will also determine the cellular and mitochondrial TDP-43 accumulation and mitochondrial structure integrity. Overall, the proposed studies will provide evidence that the eIF5AHyp pathway in the TDP-43 phenotype is upstream of irreversible stages of dementia. It also offers the first detailed mechanisms of how reducing hypusine restores glucose dysregulation and mitochondrial dysfunction, maintaining neuro-astrocytic support and healthy neuronal activity, while rescuing the pathological phenotype in animal models of TDP-43 proteinopathy.