Understanding the Role of N-WASP in the Intestinal Epithelium

描述(由申请人提供)：这个项目的总体目标是进一步深入了解肌动蛋白细胞骨架在维持肠上皮内环境平衡中所起的作用。尽管已知有广泛的细胞过程需要肌动蛋白细胞骨架的动态变化，但对调节高度专业化的肠道上皮细胞中肌动蛋白细丝组装速度的关键因素知之甚少。神经Wiskott-Aldrich综合征蛋白(N-WASP)是肌动蛋白组装的主要调节因子，在皮肤和肠道中广泛表达。为了研究它在上皮细胞中的作用，我们最近培育了一只肠道特异性缺失N-WASP的小鼠。肠道N-WASP基因敲除(INWKO)小鼠出生正常，有生育能力，但比野生型(WT)对照组小；它们具有大体正常的粘膜结构，保留了肠道细胞分化为所有肠道细胞系的能力，没有自发炎症。然而，这些小鼠表现出显著的顶端细胞异常，包括微绒毛缩短和簇状，形态异常的顶端连接复合体，以及缺乏通常与紧密连接(TJ)连续的肌动蛋白致密末端结构。INWKO小鼠在将TJ蛋白封闭蛋白靶向细胞-细胞接触部位方面也表现出缺陷。这些发现在临床上与肠道通透性的自发增加和葡聚糖硫酸钠(DSS)急性炎性损伤的敏感性显著增加有关。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发挥关键作用，而顶端细胞骨架结构是细胞间联系和细胞旁通透性调节所必需的。 公共卫生相关性：这项建议的总体目标是加深我们对调节肠道上皮结构的机制(S)的理解，使其能够在健康和疾病中发挥其屏障功能

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