Disruption of Excitable Axonal Domains by Glucose Metabolite Methylglyoxal

葡萄糖代谢物甲基乙二醛对可兴奋轴突结构域的破坏

• 批准号: 10247444
• 负责人: Keiichiro Susuki
• 金额: $ 33.05万
• 依托单位: WRIGHT STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10247444
• 关键词: Action Potentials; Affect; Age; Alzheimer' s Disease; Axon; Behavior; Brain; Brain Injuries; Brain region; Calcium; Calpain; Caspase; Characteristics; Chronic; Corpus Callosum; Data; Diabetes Mellitus; Disease; Electron Microscopy; Enzymes; Functional disorder; Glucose; Hippocampus (Brain); Immunofluorescence Immunologic; Immunofluorescence Microscopy; Impaired cognition; Impairment; In Vitro; Injections; Knockout Mice; Knowledge; Lactoylglutathione Lyase; Learning; Length; Link; Measures; Mediating; Mediator of activation protein; Metabolic; Modeling; Molecular; Mus; Mutant Strains Mice; Natural regeneration; Nerve; Nerve Degeneration; Nervous System Physiology; Nervous system structure; Neural Conduction; Neurologic; Neurologic Symptoms; Neurons; Nodal; Non-Insulin-Dependent Diabetes Mellitus; Optic Nerve; Optics; Patients; Peptides; Pharmacology; Prefrontal Cortex; Process; Public Health; Pyruvaldehyde; Ranvier' s Nodes; Reporting; Research; Role; Short-Term Memory; Signal Transduction; Structure; Testing; Time; Transgenic Mice; Translational Research; Wild Type Mouse; calpain inhibitor; calpastatin; cognitive function; comorbidity; db/db mouse; diabetic; genetic manipulation; glucose metabolism; in vivo; inhibitor/antagonist; innovation; morris water maze; multi-electrode arrays; nerve conduction study; neural network; neuronal excitability; nodal protein; non-diabetic; novel; prevent; protein complex; sciatic nerve; therapeutic target

Project summary/abstract Alterations in the excitable domains of myelinated axons, specifically the axon initial segment (AIS) and the nodes of Ranvier, are key pathophysiologies in various neurodegenerative conditions, including diabetes. Shortening of AIS length has been shown to lower neuronal excitability, and is also implicated in cognitive impairment in type 2 diabetes and Alzheimer’s disease. However, the cellular and molecular mechanisms of how these domains are altered in disease conditions remain poorly understood. This critical gap in knowledge limits the field’s ability to manipulate the AIS and nodes for treatment. The current proposal seeks to elucidate this important aspect of nervous system pathophysiology. The overall objective of this application is to identify a critical molecular link in the process of AIS and nodal disruption. The prior studies and preliminary data provided here have identified elevations in methylglyoxal (MG), a highly reactive byproduct of glucose metabolism, as a potential mediator for AIS and nodal disruption. These data also support that calpains, calcium-dependent intracellular cysteine proteases, are involved in this process. The central hypothesis is that methylglyoxal disrupts AIS and nodal protein complexes via calpain activation and inhibits nervous system function. We will test this hypothesis via three Specific Aims. Aim 1: Test the hypothesis that reduction of MG levels with novel scavenging peptides will ameliorate AIS shortening and cognitive impairment in db/db mice, an established model for type 2 diabetes. Aim 2: Test the hypothesis that elevated MG causes AIS/node changes, reduced neural network activity (Aim 2A, in vitro; mouse cortical neuron culture and multi-electrode arrays), and cognitive impairment (Aim 2B, in vivo; systemic administration of MG or inhibitor of glyoxalase 1, an enzyme that detoxifies MG, in wild-type mice). Aim 3: Test the hypothesis that calpains mediate the effects of MG on AIS/node structures, neural network activity (Aim 3A, in vitro; pharmacological calpain inhibition), and cognitive function (Aim 3B, C, in vivo; genetic manipulation of calpastatin, a specific endogenous inhibitor of calpains). Aim 3B will assess combined effects of increased MG and calpain over-activation in calpastatin knockout mice; and Aim 3C will assess increased MG and calpain inhibition in mice over-expressing calpastatin. This application is conceptually innovative, as we propose that the key targets of elevated MG are the structures of the AIS and nodes of Ranvier in live neurons. Innovative use of multi-electrode arrays will determine the effects of increased MG and AIS shortening on neural network function. The proposed research is significant, because completion of the aims will validate MG and calpains as potential targets for translational research aimed at treatments – such as the novel MG scavengers tested in Aim 1 – for comorbid cognitive impairment in type 2 diabetes. These results also have potential to impact a wide variety of neurodegenerative conditions, such as Alzheimer’s, thus ultimately providing a sustained and powerful influence on the field.

项目摘要/摘要 骨髓轴突的激动域的变化，特别是轴突初始段（AIS）和 Ranvier的节点是包括糖尿病在内的各种神经退行性疾病中的关键病理生理。 AIS长度的缩短已显示出降低神经元令人兴奋的降低，并且也与认知有关 2型糖尿病和阿尔茨海默氏病的损害。但是，细胞和分子机制 在疾病条件下，这些领域的改变如何仍然知之甚少。这一重要差距 限制了该领域操纵AIS和节点进行治疗的能力。当前的提议旨在阐明 神经系统病理生理学的这一重要方面。该应用程序的总体目的是确定 在AIS和节点破坏过程中的关键分子联系。先前的研究和初步数据 此处提供的已经确定了甲基乙醛（MG）的升高，这是一种高反应性的葡萄糖副产品 代谢，作为AIS和淋巴结中断的潜在介体。这些数据也支持calpains， 依赖钙的细胞内半胱氨酸蛋白酶参与此过程。中心假设是 甲基甘氨酸通过钙蛋白酶激活破坏AIS和淋巴结蛋白复合物，并抑制神经系统 功能。我们将通过三个特定目标检验这一假设。 AIM 1：检验降低Mg的假设 新型清除肽的水平可以改善DB/DB小鼠的AIS缩短和认知障碍， 2型糖尿病的既定模型。 AIM 2：测试升高MG引起AIS/节点的假设 变化，降低神经元网络活性（AIM 2A，体外；小鼠皮质神经元培养和多电极 阵列）和认知障碍（AIM 2B，体内；全身施用Mg或糖酶1的抑制剂， 一种在野生型小鼠中排毒Mg的酶。目标3：检验calpains介导效果的假设 MG在AIS/节点结构上，神经网络活性（AIM 3A，体外；药物钙蛋白酶抑制）和 认知功能（AIM 3B，C，In Vivo； Calpastatin的遗传操纵，Calpastatin，一种特定的内源性抑制剂 calpains）。 AIM 3B将评估CALPASTATIN中Mg和Calpain过度激活增加的综合作用 淘汰小鼠； AIM 3C将评估过度表达的小鼠中增加的Mg和Calpain抑制 calpastatin。该应用在概念上是创新的，因为我们建议升高的毫克的关键目标是 活神经元中Ranvier的AIS和节点的结构。多电极阵列的创新使用将 确定MG增加和AIS缩短对神经网络功能的影响。拟议的研究 很重要，因为目标的完成将验证Mg和Calpains作为转化的潜在目标 旨在治疗的研究 - 例如在AIM 1中测试的新型MG清除剂 - 用于合并的认知 2型糖尿病的损害。这些结果也有可能影响多种神经退行性的 因此，阿尔茨海默氏症等条件最终为该领域提供了持续和强大的影响。