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层发育畸形越来越被认为是癫痫、智力迟钝和脑瘫的常见原因。双皮质素（DCX）基因对人类的神经元迁移至关重要，突变导致男性出现X连锁无脑畸形，女性出现双皮质，从而产生严重的神经认知缺陷。我们确定了DCX基因，并在患有这种疾病的患者中发现了突变。我们确定了其作为微管相关蛋白（MAP）的作用，并通过磷酸化和去磷酸化依赖机制参与关键信号通路。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，神经突“手腕”处微管凝聚的组织以及成体干细胞迁移的要求。Dcx是一个包含Dclk1和Dclk2的基因家族的一部分，每个基因都编码具有密切匹配的Dcx结构域和激酶结构域的强脑表达蛋白。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，与无脑畸形类似，而Dcx；Dclk2基因敲除显示出严重的癫痫发作，这也是无脑畸形临床表现的一部分。然而，激酶活性在神经元发育中的作用尚不清楚。这项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。我们将利用敲除、敲入和基因拯救实验，结合先进的活细胞成像能力和体内分析，为实现这些目标提供有力的方法。

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.