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

项目总结 概述：该项目侧重于了解如何破坏钙稳态的分子基础。 导致海马网络活动中断，导致患有TSC的神经元出现适应不良反应 信号不充分。 大约33%患有自闭症谱系障碍(ASD)的儿童也有癫痫。幼儿时期 癫痫发作会导致突触可塑性受损和认知障碍，这表明 海马体可能容易受到网络兴奋性变化的影响。尽管这个问题很重要，但 癫痫发作活动与ASD的发展之间的联系尚不清楚。哺乳动物的靶标 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。 精神错乱。在拟议的研究中，我们专注于ASD的小鼠模型，结节性硬化症(TSC)， 这是一种由TSC1或2基因突变引起的疾病。我们认为，有缺陷的TSC 信号导致mTOR过度活跃和蛋白质合成不足，表现为癫痫和自闭症。那里 TSC无法治愈，治疗方法有限，需要新的治疗靶点。我们之前的工作是 证明mTOR活性抑制癫痫相关离子通道的表达。建议数 研究扩展了我们的工作，以解决海马区网络的分子机制 TSC的过度兴奋性。我们将采取多学科的方法来批判性地测试 电压门控性钙通道亚单位α-2∂-2的过度激活导致TSC 钙稳态失调和海马网活动异常。(1)在分子水平上，我们 问α-2-∂-2的表达是如何受mTOR调控的；(2)在细胞水平上，我们问α-2-∂-2‘在树突状细胞中的作用是什么 TSC缺乏树突状细胞中的钙信号和谷氨酸受体循环；以及(3)在网络水平上，我们 探讨α-2、∂-2在促进异常海马区网络活动中的作用。拟议中的工作是第一个 弥合潜在的分子/细胞机制和海马区网络之间的差距 TSC的过度兴奋性，使用新的临床前模型测量第一次的棘波和惊厥阈值 时间到了。我们的方法的优势使我们还可以使用我们的新型光遗传学测试几种干预措施 网络活动的临床前模型。值得注意的是，癫痫药物并不只针对大脑中 癫痫发作源于大脑的其他部分，如海马体，但会减少过度兴奋的神经元。 自闭症紧密相连的地方。因此，我们假设患有TSC的儿童的海马体是脆弱的。 到神经元和网络的超兴奋性。这些研究为有希望的新疗法奠定了基础。 TSC和其他与mTOR相关的复杂脑部疾病的策略，具有可能的临床应用。

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.