Mechanism of Action of the Lissencephaly Gene LIS-1

描述(申请人提供)：I型无脑畸形是一种严重的大脑发育疾病，涉及大脑皮层形成过程中神经前体细胞迁移的缺陷。它是由Lis1基因的零星突变引起的Lis1单倍体不足引起的。Lis1与血小板活化因子和胞浆动力蛋白通路有关，但目前的证据表明后者的缺陷与脑发育疾病有关。本实验室的研究表明，Lis1与细胞质动力蛋白一起作用于运动中枢和分裂细胞的皮质，位于迁移的成纤维细胞的前沿，并在生长锥体重塑过程中发挥作用。本实验室的最新结果通过对脑片的实时成像，证实了从神经发生到神经迁移的整个过程中，Lis1 RNAi对神经前体细胞的行为产生了严重的影响。本项目的第一个目标是进一步研究Lis1和细胞质动力蛋白之间的功能相互作用，以及它们相互结合的伙伴nude和Nudel。将确定蛋白质磷酸化在调节这些相互作用中的作用，以及Lis1、nude和Nudel对动力蛋白机械力化学活性的影响。目的II确定Lis1、nude和Nudel在双极神经前体细胞形态发生和运动中的作用。目的III确定Lis1、nude和Nudel在神经前体细胞在放射状神经胶质细胞分裂周期中的运动间期核振荡中的作用。胚胎啮齿动物脑片和分离的神经前体细胞将在对照、突变或RNAi处理的动物上进行活体成像，以评估对核分裂、细胞分裂、核位置控制分裂、神经胶质引导迁移和过程动力学的影响。将监测微管细胞骨架、中心体、核、Lis1、裸体和Nudel的行为，以了解观察到的脑表型效应的潜在细胞原因。这些研究对于了解正常和异常的大脑发育、细胞迁移、细胞分裂、智力低下的原因和干细胞行为具有相当大的相关性。

DESCRIPTION (provided by applicant): Type I lissencephaly is a severe brain developmental disease which involves defects in neural progenitor cell migration during the formation of the cerebral cortex. It is caused by LIS1 haploinsufficiency, resulting from sporadic mutations in the LIS1 gene. LIS1 has been implicated in the platelet activating factor and cytoplasmic dynein pathways, but current evidence suggests that defects in the latter are responsible for the brain developmental disease. Work from this lab has indicated that LIS1 functions together with cytoplasmic dynein at kinetochores and the cortex of dividing cells, at the leading edge of migrating fibroblasts, and during growth cone remodeling. Recent results from this lab have identified severe effects of LIS1 RNAi on the behavior of neural progenitor cells from neurogenesis through the entire course of radial migration by live imaging of brain slices. Aim I of this project will be to characterize further functional interactions between LIS1 and cytoplasmic dynein and their mutual binding partners NudE, and NudEL. The role of protein phosphorylation in regulating these interactions, and the effects of LIS1, NudE, and NudEL on dynein mechanochemical activity will be determined. Aim II will be to define the role of LIS1, NudE and NudEL in the morphogenesis and locomotion of bipolar neural progenitors. Aim III will be to define the role of LIS1, NudE and NudEL in the interkinetic nuclear oscillations and cell division cycle of neural progenitor cells at the radial glial stage. Live imaging of embryonic rodent brain slices and isolated neural progenitors will be performed on control, mutant, or RNAi-treated animals to evaluate effects on nucleokinesis, cell division, control of division by nuclear position, glial guided migration, and process dynamics. The behavior of the microtubule cytoskeleton, centrosomes, nuclei, LIS1, NudE, and NudEL will be monitored to understand the underlying cellular causes for observed brain phenotypic effects. These studies are of considerable relevance to understanding normal and abnormal brain development, cell migration, cell division, the causes of mental retardation, and stem cell behavior.