Molecular Mechanism of Hippocampal network excitability in a novel, in vivo model of Tuberous Sclerosis Complex

新型结节性硬化症体内模型中海马网络兴奋性的分子机制

• 批准号: 10188655
• 负责人: Kimberly Frances Raab-Graham
• 金额: $ 33.6万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-15 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10188655
• 关键词: Address; Affect; Antiepileptic Agents; Back; Behavior; Behavioral; Biochemistry; Biological Assay; Bipolar Disorder; Brain; Brain Diseases; Brain region; Calcium; Calcium Channel; Calcium Signaling; Child; Code; Complex; Data; Dendrites; Development; Disease; Epilepsy; FRAP1 gene; Foundations; Future; Genes; Genetic; Genetic Translation; Glutamate Receptor; Health; Hereditary Disease; Hippocampus (Brain); Homeostasis; Human; Hyperactivity; Image; Impaired cognition; In Vitro; Individual; Infant; Intervention; Ion Channel; Isoxazoles; Knowledge; L-Type Calcium Channels; Lead; Learning; Life; Link; Major Depressive Disorder; Measures; Membrane; Memory impairment; Modeling; Molecular; Mus; Mutation; Nature; Neurobiology; Neurologic; Neurons; Organism; Pathway interactions; Pharmaceutical Preparations; Pharmacologic Substance; Pharmacology; Phosphotransferases; Play; Pre-Clinical Model; Prevention; Propionates; Protein Biosynthesis; Proteins; Recycling; Regulation; Research Personnel; Rodent Model; Role; Schizophrenia; Seizures; Signal Pathway; Signal Transduction; Surface; Synapses; Synaptic plasticity; TSC1 gene; Testing; Time; Tuberous sclerosis protein complex; Work; autism spectrum disorder; awake; burden of illness; clinical application; comorbidity; disability; early childhood; experimental study; gene therapy; in vivo; in vivo Model; individuals with autism spectrum disorder; interdisciplinary approach; link protein; mouse model; network dysfunction; network models; neuronal excitability; new therapeutic target; novel; novel therapeutic intervention; optogenetics; overexpression; prevent; receptor recycling; response; tool; voltage

PROJECT SUMMARY Overview: The project focuses on understanding the molecular basis of how disrupted calcium homeostasis leads to disrupted hippocampal network activity that results in maladaptive responses in neurons with TSC deficient signaling. Approximately 33% of children who have autism spectrum disorder (ASD) also have epilepsy. Early childhood seizures can result in compromised synaptic plasticity and cognitive impairment, suggesting that the hippocampus may be vulnerable to changes in network excitability. Despite the importance of this problem, the connection between seizure activity and development of ASD is poorly understood. Mammalian Target of rapamycin (mTOR) is a kinase that regulates protein synthesis and is overactive in many complex brain disorders. In the proposed studies, we focus on a mouse model of ASD, Tuberous Sclerosis Complex (TSC), which is a disorder that results from mutations in either the tsc1 or 2 genes. We propose that deficient TSC signaling leads to overactive mTOR and deficient protein synthesis that manifests as epilepsy and ASD. There is no cure for TSC, treatments are limited, and new therapeutic targets are needed. Our previous work has demonstrated that mTOR activity represses the expression of epilepsy-linked ion channels. The proposed studies extend our work to address the molecular mechanisms underlying hippocampal network hyperexcitability in TSC. We will take a multidisciplinary approach to critically test the prediction that reduced expression of the voltage-gated calcium channel subunit α2∂2 by overactive mTOR signaling in TSC leads to dysregulated calcium homeostasis and aberrant hippocampal network activity. (1) At the molecular level, we ask how α2∂2 expression is regulated by mTOR; (2) at the cellular level, we ask what is α2∂2’s role in dendritic calcium signaling and glutamate receptor recycling in TSC deficient dendrites; and (3) at the network level, we address the effect of α2∂2 in promoting aberrant hippocampal network activity. The proposed work is the first to bridge the gap between underlying molecular/cellular mechanisms and hippocampal network hyperexcitability in TSC, using a novel preclinical model to measure spike and seizure threshold for the first time. The strength of our approach allows us to also test several interventions using our novel optogenetic preclinical model of network activity. Notably, seizure medications do not target only the region of the brain that seizures originate, but can reduce hyperexcitable neurons in other parts of the brain, such as the hippocampus where ASD is tightly linked. Thus, we hypothesize that the hippocampus is vulnerable in children with TSC due to neuronal and network hyperexcitabillity. These studies form the foundation for promising new therapeutic strategies for TSC and other mTOR-related, complex brain disorders, with possible clinical applications.

项目摘要 概述：该项目的重点是了解如何破坏钙稳态的分子基础， 导致海马网络活动中断，导致TSC神经元的适应不良反应 信号不足 大约33%患有自闭症谱系障碍（ASD）的儿童也患有癫痫。幼儿 癫痫发作可导致突触可塑性受损和认知障碍，这表明 海马可能易受网络兴奋性变化的影响。尽管这个问题很重要， 癫痫发作活动和ASD发展之间的联系知之甚少。的哺乳动物靶标 雷帕霉素（mTOR）是一种调节蛋白质合成的激酶，在许多复杂的大脑中过度活跃 紊乱在所提出的研究中，我们专注于ASD的小鼠模型，即巨噬细胞性硬化症复合体（TSC）， 这是一种由TSC 1或TSC 2基因突变引起的疾病。我们认为，缺乏TSC 信号传导导致mTOR过度活跃和蛋白质合成不足，表现为癫痫和ASD。那里 TSC无法治愈，治疗方法有限，需要新的治疗靶点。我们之前的工作 表明mTOR活性抑制癫痫相关离子通道的表达。拟议 研究扩展了我们的工作，以解决海马网络的分子机制 TSC中的过度兴奋。我们将采取多学科的方法来严格测试预测，减少 电压门控钙通道亚单位α2 β 2通过TSC中过度活跃的mTOR信号传导的表达导致 钙稳态失调和海马网络活动异常。(1)在分子水平上，我们 问mTOR如何调节α2 β 2表达;（2）在细胞水平，我们问α2 β 2在树突状细胞中的作用是什么， 钙信号和谷氨酸受体在TSC缺陷树突的再循环;和（3）在网络水平，我们 阐明α2 β 2在促进异常海马网络活动中的作用。提出的工作是第一个 弥合潜在分子/细胞机制与海马网络之间的差距 TSC的过度兴奋，使用一种新的临床前模型来测量第一次发作的尖峰和癫痫发作阈值。 时间我们方法的优势使我们能够使用我们的新型光遗传学方法测试几种干预措施。 网络活动的临床前模型。值得注意的是，癫痫药物不仅针对大脑的区域， 癫痫发作起源，但可以减少大脑其他部位的过度兴奋神经元，如海马体 ASD是紧密相连的因此，我们假设，海马是脆弱的TSC儿童，由于 神经元和网络的过度兴奋。这些研究为有前途的新治疗方法奠定了基础。 策略TSC和其他mTOR相关的，复杂的大脑疾病，可能的临床应用。