Mechanism of Action of the Lissencephaly Gene LIS-1

描述（由申请人提供）：I型无脑回畸形是一种严重的脑发育疾病，涉及大脑皮层形成期间神经祖细胞迁移缺陷。它是由LIS1单倍不足引起的，由LIS1基因的零星突变引起。LIS1与血小板活化因子和细胞质动力蛋白通路有关，但目前的证据表明，后者的缺陷是脑发育疾病的原因。该实验室的工作表明，LIS1与细胞质动力蛋白一起在着丝粒和分裂细胞的皮质中，在迁移成纤维细胞的前沿，以及在生长锥重塑期间发挥作用。该实验室最近的结果已经通过脑切片的实时成像确定了LIS1 RNAi对神经前体细胞行为的严重影响，从神经发生到放射状迁移的整个过程。本项目的目的是进一步研究LIS1和细胞质动力蛋白及其相互结合伙伴NudE和NudEL之间的功能相互作用。蛋白磷酸化在调节这些相互作用中的作用，以及LIS1、NudE和NudEL对动力蛋白机械化学活性的影响将被确定。目的II将是确定的作用LIS1，NudE和NudEL双极神经祖细胞的形态发生和运动。目的III将确定的作用，LIS1，NudE和NudEL在核内振荡和细胞分裂周期的神经前体细胞在放射状胶质阶段。将对对照、突变体或RNAi处理的动物进行胚胎啮齿动物脑切片和分离的神经祖细胞的实时成像，以评价对核分裂、细胞分裂、通过核位置控制分裂、胶质细胞引导的迁移和过程动力学的影响。将监测微管细胞骨架、中心体、细胞核、LIS1、NudE和NudEL的行为，以了解观察到的脑表型效应的潜在细胞原因。这些研究对于理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.