Understanding the Role of N-WASP in the Intestinal Epithelium

描述（由申请人提供）：本项目的总体目标是进一步了解肌动蛋白细胞骨架在维持肠上皮内稳态中的作用。尽管广泛的细胞过程中，已知需要动态变化的肌动蛋白细胞骨架，很少有人知道的因素，是至关重要的调节率肌动蛋白丝组装在高度专业化的上皮细胞的肠。神经Wiskott-Aldrich综合征蛋白（N-WASP）是肌动蛋白组装的主要调节剂，其广泛表达，包括在皮肤和肠道中。为了研究其在上皮细胞中的作用，我们最近产生了一只肠道特异性缺失N-WASP的小鼠。肠N-WASP敲除（iNWKO）小鼠正常出生并且是可生育的，但是比野生型（WT）对照小;它们具有大体上正常的粘膜结构，肠细胞分化成所有肠细胞谱系的能力得以保留，并且没有自发性炎症。然而，这些小鼠表现出惊人的顶端细胞异常，包括缩短和成簇的微绒毛和形态异常的顶端连接复合体和肌动蛋白致密的末端结构，通常是在连续的紧密连接（TJ）的情况下。iNWKO小鼠在将TJ蛋白闭合蛋白靶向细胞-细胞接触位点方面也表现出缺陷。这些发现在临床上与肠通透性的自发增加和对葡聚糖硫酸钠（DSS）的急性炎症损伤的敏感性的显著增加相关。我们的总体假设是，N-WASP在顶端细胞骨架结构的动态调节中起着至关重要的作用，这些结构对于细胞间接触和细胞旁通透性的调节至关重要。 公共卫生相关性：本提案的总体目标是进一步了解调节肠上皮结构的机制，使其能够在健康和疾病中发挥屏障功能

DESCRIPTION (provided by applicant): The overall goal of this project is to gain further insight into the role that the actin cytoskeleton plays in maintaining homeostasis in the intestinal epithelium. Despite the broad range of cellular processes that are known to require dynamic changes in the actin cytoskeleton, very little is known about the factors that are critical for regulating the rate of actin filament assembly in the highly specialized epithelial cells of the intestine. The Neural Wiskott-Aldrich Syndrome protein (N-WASP) is a major regulator of actin assembly that is ubiquitously expressed, including in the skin and the gut. In order to study its role in epithelial cells, we have recently generated a mouse with gut-specific deletion of N-WASP. Intestinal N-WASP knock-out (iNWKO) mice are born normally and are fertile but are smaller than wild type (WT) controls; they have grossly normal mucosal architecture, with preserved ability of the enterocytes to differentiate into all intestinal cell lineages, and there is no spontaneous inflammation. These mice however exhibit striking apical cell abnormalities, including shortened and clustered microvilli and morphologically abnormal apical junction complexes and the absence of actin dense terminal structures that normally are in continuity with the tight junctions (TJs). iNWKO mice also exhibit defects in targeting the TJ protein occludin to sites of cell-cell contact. These findings correlate clinically with a spontaneous increase in intestinal permeability and dramatic increase in susceptibility to acute inflammatory insult with dextran sodium sulfate (DSS). Our overall hypothesis is that N-WASP plays a critical role in the dynamic regulation of apical cytoskeletal structures which are essential for intercellular contacts and the regulation of paracellular permeability. PUBLIC HEALTH RELEVANCE: The overall goal of this proposal is to further our understanding of the mechanism(s) that regulate intestinal epithelial structure and enable it to perform its barrier function in both health and disease