Role of neuronal migration genes in synaptogenesis and plasticity

描述（由申请人提供）：在自闭症和精神分裂症的临床材料和动物模型中，包括在脆性- x智力迟钝蛋白（FMRP）和Rett基因MeCP2突变的小鼠中，脊柱和突触密度异常。心理健康研究的一个主要焦点是确定发育中的大脑突触形成和持续的调节机制。目前关于自闭症行为的假设不仅包括突触接触错误的形成，还包括在儿童发育过程中未能成功修剪已形成的突触或建立新的连接。丝状足极有可能是树突棘的前身，树突棘是大多数突触的所在地，两者都依赖于它们的运动性来取样、测试，并最终形成接触和突触，形成适当的回路。虽然许多树突棘在一生中都保持着，但许多棘被消除，新的棘形成，这些新棘可以反映失去的记忆或新的接触，从而获得记忆。虽然有强烈的迹象表明其潜在的重要性，Lis1在信号转导和迁移后神经元运动中的作用基本上是一个未知的研究领域。我们实验室之前的研究表明，Lis1显著影响小gtpase RhoA、Rac1和Cdc42的调控，Lis1单倍不足会损害这些rho家族gtpase在nmda受体介导的钙内流中的激活，这与Lis1的信号转导作用是一致的。此外，Lis1单倍不全与海马和小脑神经元神经突丝状足形成的显著减少有关。我们提出证明Lis1在树突丝状伪足和脊柱的形成和运动中起着重要作用，并转化为突触的形成和稳定性。这将进一步阐明Lis1作为突触发生和可塑性重要分子的新作用。我们将研究Lis1水平对树突丝状足和棘运动的依赖性。利用旋转盘共聚焦和双光子成像，我们将分别分析体外和体内系统中丝状足和脊柱的发育和形态。最后，我们将进行实验，通过分析已知的Lis1相互作用物，包括nudE异构体nde -like 1 （NDEL1）和NDEL1相互作用蛋白DISC1，重点了解控制这些事件的分子机制。Lis1可能在外部线索和支撑活动依赖性突触可塑性的细胞骨架调节之间提供了一个关键的联系。

DESCRIPTION (provided by applicant): Spine and synapse density are abnormal in clinical material and in animal models of autism and schizophrenia, including in mice bearing mutations in the fragile-X mental retardation protein (FMRP) and the Rett gene, MeCP2. A major focus in mental health research is defining the mechanisms regulating formation and persistence of synapses in developing brain. Current hypotheses regarding autistic behaviors include not only formation of faulty synaptic contacts but also failure to successfully prune synapses once formed or make new connections during childhood development. Filopodia are the most likely predecessor of dendritic spines, the sites of most synapses, and both rely on their motility in order to sample, test and finally make contacts and synapses to form proper circuits. While a lot of dendritic spines are maintained throughout life, many spines are eliminated and new spines are formed that could reflect memories lost or new contacts, and thus memories, gained. While there are strong indications of its potential importance, the role of Lis1 in signal transduction and post-migration neuronal motility is an essentially uncharted area of investigation. Our laboratory has previously shown that Lis1 significantly influences the regulation of small GTPases RhoA, Rac1 and Cdc42, that Lis1 happloinsufficiency impairs the activation of these Rho-family GTPases upon NMDA-receptor mediated calcium influx, and that is consistent with a signal transduction role for Lis1. Moreover, Lis1 happloinsufficiency is associated with marked reduction in filopodia formation on neurites of hippocampal and cerebellar neurons. We propose to demonstrate that Lis1 plays a prominent role in dendritic filopodia and spine formation and motility that translates into synapse formation and stability. This will further elucidate a new role of Lis1, as a molecule important for synaptogenesis and plasticity. We will investigate the dependence of Lis1 levels on the motility of dendritic filopodia and spines. Using spining-disc confocal and two-photon imaging, we will analyze development and morphology of both filopodia and spines in in vitro and in vivo systems, respectively. Finally, we will conduct experiments that will focus on understanding molecular mechanisms governing these events by analyzing known Lis1 interactors, including the nudE isoform NudE-like 1 (NDEL1) and NDEL1 interacting protein DISC1. Lis1 may provide a critical link between external cues and cytoskeletal modulation underpinning activity-dependent synaptic plasticity. PUBLIC HEALTH RELEVANCE: This project combines genetics, cellular and systems neurobiology with the goal of understanding how the brain is affected in mental health disorders. One of the mechanisms underlying mental health diseases, specifically of schizophrenia and autism, is improper connection between neurons that in turn results in overall abnormal neural circuit function. We will investigate the role of Lis1 in the regulation of proper formation and elimination of connections between neurons that must be carefully orchestrated throughout development.