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，包括携带脆性X智力低下蛋白（FMRP）和Rett基因MeCP 2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错误突触接触的形成，而且还包括在儿童发育期间一旦形成或建立新连接就无法成功修剪突触。丝状伪足最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采样、测试并最终使接触和突触形成适当的回路。虽然许多树突棘在整个生命过程中都会保持，但许多棘会被消除，新的棘会形成，这可能反映了失去的记忆或新的联系，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的作用是一个基本上未知的调查领域。我们的实验室以前已经表明，Lis1显着影响小GTP酶RhoA，Rac 1和Cdc 42的调节，Lis1 happloinsufficiency削弱这些Rho家族GTP酶激活NMDA受体介导的钙离子内流，这是一致的信号转导作用Lis1。此外，Lis1 happloinsufficiency与海马和小脑神经元突起上的丝状伪足形成显著减少有关。我们建议证明，Lis1在树突丝状伪足和脊柱的形成和运动，转化为突触的形成和稳定性中发挥着重要作用。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。我们将调查的依赖性的Lis1水平的树突状丝状伪足和刺的运动。利用旋转圆盘共聚焦和双光子成像技术，我们将分别在体外和体内系统中分析丝状伪足和棘的发育和形态。最后，我们将进行实验，重点是通过分析已知的Lis1相互作用物，包括nudE亚型NudE样1（NDEL1）和NDEL1相互作用蛋白DISC1，了解控制这些事件的分子机制。Lis1可能提供了一个关键的外部线索和细胞骨架调制支持活动依赖性突触可塑性之间的联系。 公共卫生相关性：该项目结合了遗传学，细胞和系统神经生物学，旨在了解大脑如何影响精神健康障碍。精神健康疾病的潜在机制之一，特别是精神分裂症和自闭症，是神经元之间的不正确连接，从而导致整体异常的神经回路功能。我们将研究Lis1在调节神经元之间连接的正确形成和消除中的作用，这些连接必须在整个发育过程中精心策划。

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.