The Lis1-Nde1 pathway in cerebral cortical development

描述(由申请人提供)：大脑皮质发育遗传畸形是癫痫和智力低下临床病例的一大部分基础。了解这些发育障碍的一个有力工具是分析它们的致病基因。众所周知，Lis1基因的杂合突变会导致无脑(平滑大脑)，这是一种严重的神经遗传综合征，表现为顽固性癫痫、严重的智力低下和婴儿早期死亡。Lis1基因编码的是一种细胞质蛋白，没有明显的内在酶活性，其分子和细胞功能可能是通过蛋白质之间的相互作用来发挥作用的。我们证明了Lis1与NDE1在物理和功能上都相互作用。通过对Lis1-NDE1双突变小鼠的一系列等位基因的分析，我们证明了Lis1和NDE1在调节神经前体细胞的自我更新和分化方面形成了剂量依赖性的复合体。在大脑皮层神经发生初期，功能突变的双缺失导致神经前体细胞出现严重的有丝分裂、形态和黏附缺陷，导致大脑皮层体积缩小80%以上，皮质神经元严重紊乱。我们建议针对特定目的1对突变小鼠的皮质发育缺陷进行详细的分析，以了解神经前体细胞的增殖自我更新和神经源性分化是如何受到其基本结构特征如形态、有丝分裂模式、侧向粘连和细胞结构组织的控制的。我们还将通过研究培养中的Lis1-NDE1突变前体细胞和分析NDE1结合蛋白来探索特定目的2中Lis1-NDE1复合体控制神经发生的细胞分子机制。这项工作将有助于理解Lis1-NDE1通路对皮质神经发生的分子调控，也将有助于更广泛地了解大脑皮层发育的机制以及无脑和其他遗传性皮质畸形疾病的发病机制。 与公共卫生相关：LIS1基因突变导致无脑综合征(平滑大脑)，这是一种严重的发育遗传疾病，大脑皮层畸形，顽固性癫痫和严重的精神发育迟滞。该提案概述了结合小鼠遗传学和细胞生物学实验来研究Lis1及其相关NDE1基因在大脑皮层发育过程中调节自我更新和神经发生的功能。

DESCRIPTION (provided by applicant): Developmental genetic malformations of the cerebral cortex underlie a large fraction of clinical cases of epilepsy and mental retardation. A powerful tool for understanding these developmental disorders is to analyze their causative genes. Heterozygous mutations of the LIS1 gene are known to cause lissencephaly (smooth brain), a severe neurogenetic syndrome manifested by intractable epilepsy, profound mental retardation and early infantile death. LIS1 gene encodes a cytoplasmic protein with no apparent intrinsic enzymatic activity; its molecular and cellular function may act via protein-protein interactions. We show that LIS1 interacts with Nde1 both physically and functionally. By analyzing an allelic series of Lis1-Nde1 double mutant mice, we demonstrated that Lis1 and Nde1 form a dosage dependent complex in regulating the self-renewal and differentiation of neural progenitors. Lis1-Nde1 double loss of functional mutations resulted in severe mitotic, morphological and adhesion defects of neural progenitors at the onset of cerebral cortical neurogenesis, leading to an over 80% reduction in the size of the cerebral cortex and severe disorganizations of cortical neurons. We propose to perform detailed analyses on cortical developmental defects of Lis1 and Nde1 mutant mice in Specific Aim 1 to understand how the proliferative self-renewal and the neurogenic differentiation of neural progenitors are controlled by their basic structural features such as morphology, mitotic pattern, lateral adhesions and cytoarchitectural organizations. We will also explore the cell molecular mechanisms that underlie the neurogenesis control by the Lis1-Nde1 complex in Specific Aim 2 through studying Lis1- Nde1 mutant progenitors in cultures and analyzing Nde1 binding proteins. The proposed work will help to understand the molecular control of cortical neurogenesis by the Lis1- Nde1 pathway, and will also gain a broader insight into mechanisms governing cerebral cortex development as well as pathogenesis of lissencephaly and other genetic cortical malformation diseases. PUBLIC HEALTH RELEVANCE: Mutations of the LIS1 gene cause lissencephaly syndrome (smooth brain), a severe developmental genetic disorder with a malformed cerebral cortex, intractable epilepsy and profound mental retardation. The proposal outlines combined mouse genetic and cell biological experiments to study the function of LIS1 and its associated Nde1 genes in regulating the self- renewal and neurogenesis during cerebral cortical development.