Doublecortin in Neuronal Migration

描述(由申请人提供)：由于神经元迁移障碍引起的皮质发育畸形日益被认为是癫痫、智力低下和脑性瘫痪的常见原因。双重皮质素(DCX)基因对人类神经元迁移至关重要，因为突变会导致男性X连锁无脑，女性双皮质，导致严重的神经认知缺陷。我们鉴定了DCX基因，并在患有这种疾病的患者中发现了突变。我们确定了它作为微管相关蛋白(MAP)的作用，以及它通过磷酸化和去磷酸化依赖的机制参与关键的信号通路。我们发现了DCX在细胞中的重要细胞作用，包括介导核-中心体偶联，在轴突“腕”处组织微管凝聚，以及成年干细胞迁移所必需的。DCX是一个基因家族的一部分，该家族还包含Dclk1和Dclk2，每个基因都编码一个强脑表达的蛋白，具有紧密匹配的DCX结构域和激活域。我们发现，Dcx；Dclk1基因敲除显示出严重的皮质神经元迁移缺陷，反映了无脑畸形，而Dcx；Dclk2基因敲除显示出严重的癫痫发作，这也是无脑畸形的临床图景的一部分。然而，该激酶活性在神经元发育中的作用尚不清楚。这一更新应用的总体目标是阐明DCX基因家族在神经元发育和脑功能中的信号机制。我们将利用小鼠的基因敲除、敲入和遗传拯救实验，结合先进的活细胞成像能力和体内分析，这将协同提供一种强大的方法来实现这些目标。 公共卫生相关性：双皮质素基因家族在大脑发育中发挥关键作用，当突变时会导致严重形式的癫痫和智力低下。我们将研究双皮质素基因家族的信号机制，以了解这些人类疾病的基础。

DESCRIPTION (provided by applicant): Malformations of cortical development due to disorder of neuronal migration are increasingly recognized as a common cause of epilepsy, mental retardation, and cerebral palsy. The doublecortin (DCX) gene is critical for neuronal migration in humans, as mutations result in X- linked lissencephaly in males and double cortex in females, producing severe neurocognitive deficits. We identified the DCX gene and found mutations in patients with this condition. We identified its role as a microtubule-associated protein (MAP) and its involvement in critical signaling pathways through phosphorylation- and dephosphorylation-dependent mechanisms. We uncovered important cellular roles for Dcx in cells, including mediation of nuclear-centrosome coupling, organization of microtubule condensation at the neurite "wrist" and a requirement in adult stem cell migration. Dcx is part of a gene family also containing Dclk1 and Dclk2, each encoding a strongly brain-expressed protein with a closely matching Dcx domain and kinase domain. We found that Dcx;Dclk1 knockouts displays severe cortical neuronal migration defects that mirror lissencephaly, whereas Dcx;Dclk2 knockouts displays severe seizures, also part of the clinical picture of lissencephaly. However, the role of the kinase activities in neuronal development are unknown. The overall goal of this renewal application is to elucidate the signaling mechanisms of the Dcx gene family in neuronal development and brain function. We will utilize knockout and knock-in and genetic rescue experiments in mice combined with advanced live-cell imaging capabilities and in vivo analysis that will synergize to provide a powerful approach to address these goals. PUBLIC HEALTH RELEVANCE: The doublecortin gene family plays critical roles in brain development, resulting in severe forms of epilepsy and mental retardation when mutated. We will study the signaling mechanisms of the doublecortin gene family, in order to understand the basis of these human diseases.