Motor Proteins in Brain Development

描述（由申请人提供）：新皮层神经发生和迁移缺陷导致严重的脑发育疾病。LIS 1突变导致无脑畸形（平滑脑），是第一个被发现的神经元迁移基因。LIS 1在细胞质动力蛋白通路中发挥作用，表明微管运动蛋白在脑发育中发挥作用。在早期的研究中，我们确定了神经发生和迁移中多个离散的LIS 1和动力蛋白需要阶段，从而建立了经典（I型）无脑回畸形细胞基础的综合模型。我们还发现LIS 1是长期神秘的细胞周期依赖性核间迁移（INM）所必需的，这是神经上皮和放射状胶质祖细胞（RGPC）行为的一般特征。我们已经进一步确定，INM需要相反方向的微管马达蛋白，正末端定向的非常规驱动蛋白Kif 1a和细胞质动力蛋白的活性。这一模式似乎解释了INM的基本机制，并应使我们能够进一步解决有关其功能和目的的基本和长期问题。具体目的是确定Kif 1a的核转运机制;确定基底和顶端INM的特异性抑制如何影响细胞周期进程和细胞命运;以及确定使用小分子蛋白激酶抑制剂和其他试剂控制INM的细胞周期机制。这些问题对于理解大脑的大小、组成和组织是如何控制的，以及干细胞增殖在正常或肿瘤条件下是如何调节的具有重要意义。对负责INM的基因的分析和小分子细胞周期抑制剂的使用也将确定在早期脑发育期间调节神经发生和迁移的潜在靶点。 公共卫生相关性：该提案涉及发育中大脑中神经祖细胞行为的机制。我们将测试抑制特定基因和蛋白激酶对祖细胞发育命运的影响。这些研究将确定重要的新的治疗目标的发展条件，并阐明小头畸形，无脑畸形，异位性疾病的原因。

DESCRIPTION (provided by applicant): Defects in neocortical neurogenesis and migration cause severe brain developmental disease. LIS1, mutations in which cause lissencephaly (smooth brain), was the first neuronal migration gene to be identified. LIS1 functions in the cytoplasmic dynein pathway, indicating that microtubule motor proteins play a role in brain development. In earlier work supported by this grant we identified multiple discrete LIS1- and dynein- requiring stages in neurogenesis and migration, leading to a comprehensive model for the cellular basis of classical (type I) lissencephaly. We also found LIS1 to be required for the long-mysterious cell-cycle- dependent interkinetic nuclear migration (INM), a general feature of neuroepithelial and radial glial progenitor cell (RGPC) behavior. We have determined further that INM requires the activity of opposite-directed microtubule motor proteins, the plus end-directed unconventional kinesin Kif1a and cytoplasmic dynein. This model appears to explain the underlying mechanism for INM, and should allow us to address further basic and long-standing questions regarding its function and purpose. The Specific Aims are to determine the mechanism of nuclear transport by Kif1a; to determine how specific inhibition of basal and apical INM affect cell cycle progression and cell fate; and to determine the mechanisms for cell cycle control of INM using small molecule protein kinase inhibitors and other reagents. These issues have important implications for understanding how brain size, composition, and organization are controlled, and how stem cell proliferation is regulated under normal or neoplastic conditions. The analysis of genes responsible for INM and the use of small molecule cell cycle inhibitors will also identify potential targets for modulating neurogenesis and migration during early brain development. PUBLIC HEALTH RELEVANCE: This proposal addresses the mechanisms responsible for neural progenitor cell behavior in the developing brain. We will test the consequences of inhibiting specific genes and protein kinases on the developmental fate of progenitor cells. These studies will identify important new therapeutic targets for developmental conditions, and elucidate the causes of microcephaly, lissencephaly, and heterotopic disorders.