Synaptic changes and hypersynchronous network activity in mTORopathies

项目摘要 超激活雷帕霉素（mTOR）信号传导机制靶点的遗传变异是最常见的遗传变异之一。 与难治性小儿癫痫相关的常见病理基质，以及 mTOR通路也被提出介导癫痫发生以响应脑损伤。虽然改变了 神经元迁移和形态学是许多已知mTOR相关神经疾病的标志 在人类中，动物模型的研究表明，异常的突触传递和网络 活动先于或发生在没有明显结构变化的情况下， 并不能预防神经系统症状这突出表明需要更好地了解 大脑的功能变化。这项提议将检验异常同步神经元 由mTOR信号通路的遗传超活化引起的活性是由突触的变化驱动的。 传输长期目标是了解这种异常的成因，然后预防或挽救这种异常 活动，这可能是mTORopathies患者癫痫和自闭症高发病率的基础。 在目标1中，我们将通过测试mTORopathies的四种遗传模型（Tsc1，Pten，Pik3ca，Szt2）和 确定是否有共同的突触变化。不同的mTOR病变是否有共同的 突触改变是理解这些分子机制相似性的一个基本问题， 相关疾病。在目标2中，我们将使用分子遗传拯救策略来分离形态学 和mTOR超激活的突触效应，以测试突触变化是否足以诱导 超同步活动和癫痫。在目标3中，我们将使用宽场和双光子钙的组合 成像以跟踪体内超同步活动的发展和特征。然后我们将测试 我们在体外观察到的突触变化是否存在于超同步的时间和地点， 活动开始，以及它们是否可以驱动异常的网络活动。我们预计定义函数 与增强的神经元兴奋性相关的mTOR超活化的后果将导致显著的 在疾病机制的理解的进步，并帮助治疗策略的发展， mTOR病和其他神经系统疾病。

Project Summary Genetic variants that hyperactivate mechanistic target of rapamycin (mTOR) signaling are among the most common pathological substrates associated with intractable pediatric epilepsy, and hyperactivation of the mTOR pathway is also proposed to mediate epileptogenesis in response to brain injury. Although altered neuronal migration and morphology are hallmarks of many known mTOR-related neurological diseases (mTORopathies) in humans, studies in animal models show that abnormal synaptic transmission and network activity precede or occur in the absence of overt structural changes, and that preventing structural changes does not prevent the neurological symptoms. This highlights the need for a better understanding of the functional changes in the brain. This proposal will test the hypothesis that abnormal synchronous neuronal activity caused by genetic hyperactivation of the mTOR signaling pathway is driven by changes in synaptic transmission. The long-term goal is to understand the genesis of, and then prevent or rescue, this abnormal activity, which may underlie both the high incidence of epilepsy and autism in humans with mTORopathies. In Aim 1, we will address this by testing four genetic models of mTORopathies (Tsc1, Pten, Pik3ca, Szt2) and determining whether there are common synaptic changes. Whether different mTORopathies share common synaptic alterations is an essential question to understanding the mechanistic similarity of these molecularly related diseases. In Aim 2, we will use molecular genetic rescue strategies that dissociate the morphological and synaptic effects of mTOR hyperactivation to test whether synaptic changes are sufficient to induce hypersynchronous activity and epilepsy. In Aim 3, we will use a combination of widefield and 2-photon calcium imaging to track the development and characteristics of hypersynchronous activity in vivo. We will then test whether the synaptic changes we observe in vitro are present at the time and place of hypersynchronous activity onset, and whether they can drive aberrant network activity. We anticipate that defining the functional consequences of mTOR hyperactivation relevant to enhanced neuronal excitability will lead to significant advances in the understanding of disease mechanisms, and aid the development of treatment strategies for mTORpathies and other neurological diseases.