Regulation Of Cortical Neurogenesis By Apical Complex Proteins

描述（由申请人提供）：大脑皮质的正常发育取决于皮质祖细胞的增殖和分化的成功控制，这是由细胞和分子事件紧密协调的，所述细胞和分子事件平衡早期出生的神经元的产生与后期出生的神经元的祖细胞的维持。当这一关键的发育过程没有正常发生时，就会导致皮质结构的异常，通常会导致发育障碍，如智力迟钝、癫痫和自闭症。最近的研究表明，顶端复合物蛋白的功能是重要的，在维持祖细胞的命运。Pals 1是神经前体细胞中的支架蛋白和顶端复合物蛋白的中心组分。为了阐明顶端复合物蛋白控制祖细胞增殖的分子机制，建立了Pals 1条件性基因敲除小鼠模型。Pals 1的缺失导致神经上皮祖细胞自我更新的缺陷，导致它们过早地退出细胞周期。在Pals 1缺陷小鼠中观察到的细胞命运变化伴随着顶端复合物蛋白和粘附连接（AJ）蛋白的异常分布以及膜结构的破坏。基于这些观察结果，我们假设，Pals 1协调控制神经祖细胞增殖和最终的命运，在大脑皮层细胞通过调节膜结构和细胞极性，通过与顶端复合物蛋白和AJ组件的相互作用。为了检验这一假设，将检查Pals 1在放射状胶质祖细胞（RGP）的细胞命运决定中的功能，放射状胶质祖细胞（RGP）产生大多数神经元。Pals 1在细胞命运中的直接功能将通过表征RGP中Pals 1缺失引起的细胞命运变化以及通过分析蛋白质的极化形状和分布的变化来确定。为了确定Pals 1在有丝分裂中的分布和功能，我们将检查有丝分裂过程中Pals 1分布的动态，并根据Pals 1遗传或Pals 1亚细胞定位的变化来跟踪子细胞的命运;并通过分析Pals 1缺陷的RGP的有丝分裂缺陷来定义Pals 1在祖细胞分裂中的功能。最后，描绘的分子途径，根据Pals 1功能的细胞命运的决定，我们将检查Pals 1的功能，在调节形成的粘附细胞-细胞连接的顶端复合物的组装，并针对钙粘蛋白AJ和侧细胞连接。我们还将探索Pals 1在建立局部信号传导中的功能，该信号传导通过与Par复合物的相互作用对细胞命运决定至关重要。这项研究的结果将提供有关神经祖细胞的增殖控制在正常发育过程中是如何调节的有价值的信息，并可能导致对造成破坏性神经发育障碍的机制的重要见解。 公共卫生相关性：大脑皮层发育的异常往往会导致毁灭性的神经系统疾病，如精神发育迟滞、自闭症和癫痫。对神经前体细胞增殖调控分子机制的研究，不仅有助于更好地了解大脑皮层的正常发育，而且有助于了解疾病的发病机制，为将来的治疗和预防提供可能。

DESCRIPTION (provided by applicant): Normal development of the cerebral cortex depends upon the successful control of proliferation and differentiation of cortical progenitor cells, which is tightly orchestrated by cellular and molecular events that balance the generation of early-born neurons with the maintenance of progenitors for later-born neurons. When this crucial developmental process does not occur properly, abnormalities in the cortical structure are a result, often leading to developmental disabilities such as mental retardation, epilepsy, and autism. Recent studies have shown that the function of apical complex proteins is important in maintaining the progenitor fate. Pals1 is a scaffolding protein and a central component of apical complex proteins in the neural progenitor cells. To delineate the molecular mechanisms that control progenitor proliferation by apical complex proteins, Pals1 conditional knockout mouse model was generated. Loss of Pals1 causes defects in self-renewal of neural epithelial progenitors, leading to their exit of the cell cycle prematurely. The cell fate changes seen in the Pals1-deficient mice are accompanied by aberrant distribution of apical complex proteins and adherens junction (AJ) proteins, and disrupted membrane structure. Based on these observations, we hypothesize that Pals1 orchestrates the control of neural progenitor proliferation and the ultimate fate of cells in the cerebral cortex by regulating membrane architecture and cell polarity through interaction with apical complex proteins and AJ components. To test this hypothesis, the function of Pals1 in cell fate decision of radial glia progenitors (RGPs), which generate the majority of neurons, will be examined. The direct function of Pals1 in the cell fate will be determined by characterizing the cell fate changes elicited by Pals1 loss in the RGPs, and by analyzing the changes in the polarized shape and distribution of proteins. To determine the Pals1 distribution and function in mitosis, we will examine the dynamics of Pals1 distribution during mitosis and follow the fate of daughter cells, depending on Pals1 inheritance or changes in subcellular localization of Pals1; and define the Pals1 function in progenitor division by analyzing the mitosis defects of Pals1-deficient RGPs through time-lapse imaging. Lastly, to delineate the molecular pathways that underlie Pals1 function of cell fate decision, we will examine the Pals1 function in regulating the formation of adhesive cell-cell junction by the assembly of the apical complex, and targeting of cadherins to AJ and the lateral cell junction. We will also explore the Pals1 function in establishment of local signaling(s) that is essential for cell fate decision by interaction with the Par complex. The results of this study will provide valuable information regarding how proliferation control of neural progenitor cells is regulated during normal development, and may lead to important insights about the mechanisms causing devastating neurodevelopmental disorders. PUBLIC HEALTH RELEVANCE: Abnormalities in the development of cerebral cortex often cause devastating neurological disorders such as mental retardation, autism and epilepsy. The studies of molecular mechanisms that control neural progenitor proliferation will provide not only the better understanding of normal development of cerebral cortex, but also knowledge about disease causing mechanism that may lead to the potential therapeutics and possible prevention in the future.