Regulation of Apical Specific Endocytosis in the C. elegans Intestine

描述（由申请人提供）：我们在本提案中的目标是识别和理解将内吞货物从顶端质膜内化和运输到肠上皮细胞（肠细胞）溶酶体的细胞成分。许多上皮细胞表面受体、离子通道和其他与人类疾病有关的整体膜蛋白特异性地定位于顶膜。它们在根尖表面的稳态丰度很大程度上取决于它们通过分泌和内吞作用从质膜中插入和移除的相对速率。为了获得驱动这一途径的机制的新见解，我们建议在这些研究中率先使用微观线虫C. elegans。我们将利用这一系统独特的实验特点，为这一研究领域创造一个新的、高度简化的、基因可操纵的范式。使秀丽隐杆线虫在几乎所有现代生物学研究领域成为领先模式生物的主要特征是其高度先进的遗传学，包括极其容易的基因敲除、敲除和转基因技术，再加上透明的身体，可以在完整生物体的生理相关背景下可视化荧光标记的分子。我们的初步研究已经发现了一种通过Rac1/CED-10调控根尖内吞的新途径。进一步的分析将剖析这一途径控制根尖内吞作用的机制。此外，我们计划应用秀丽隐杆线虫中可用的独特遗传工具来鉴定哺乳动物中保守的顶端内吞作用的其他调节因子。秀丽隐杆线虫作为具有真正肠上皮的最简单的动物模型，有可能回答关于顶端肠功能机制的关键问题，并可以为催化未来研究哺乳动物肠上皮中高度相关的通路提供关键框架。公共卫生相关性。我们的目标是鉴定和理解将大分子从顶质膜内化和运输到肠上皮细胞（肠细胞）溶酶体的细胞成分。许多与人类疾病相关的重要蛋白质都是通过肠细胞内吞作用从顶膜上特异性摄取的，这与其他类型细胞的相关过程有重要区别。因此，这项研究将与营养摄取、体液平衡和痢疾以及胎儿抗体转运有关。

DESCRIPTION (provided by applicant): Our goal in this proposal is to identify and understand the cellular components that internalize and transport endocytic cargo from the apical plasma membrane to the lysosomes of intestinal epithelial cells (enterocytes). Many epithelial cell surface receptors, ion channels, and other integral membrane proteins implicated in human disease are specifically localized to the apical membrane. Their steady-state abundance on the apical surface is largely controlled by their relative rates of insertion and removal from the plasma membrane by secretion and endocytosis. To gain new insight into the mechanisms that drive this pathway, we propose to pioneer the use of the microscopic nematode worm C. elegans for these studies. We will take advantage of the unique experimental features of this system, creating a new, highly simplified, and genetically manipulatable paradigm for this research area. Chief among the features that have made C. elegans a leading model organism in nearly all areas of modern biological research are its highly advanced genetics, including extremely facile gene knockdown, knockout, and transgenic technology, coupled with a transparent body that allows visualization of fluorescently tagged molecules in the physiologically relevant context of the intact living organism. Our preliminary studies have already uncovered a novel regulatory pathway controlling apical endocytosis through Rac1/CED-10. Further analysis will dissect the mechanisms by which this pathway controls apical endocytosis. In addition, we plan to apply the unique genetic tools available in C. elegans to identify additional regulators of apical endocytosis conserved with mammals. As the simplest animal model possessing a true intestinal epithelium, C. elegans has the potential to answer key questions regarding the mechanism of apical intestinal function, and can provide a key framework that catalyzes future investigation into the highly related pathways in mammalian intestinal epithelia. PUBLIC HEALTH RELEVANCE. Our goal in this proposal is to identify and understand the cellular components that internalize and transport macromolecules from the apical plasma membrane to the lysosomes of intestinal epithelial cells (enterocytes). Many important proteins implicated in human disease are specifically taken up from the apical membrane by endocytosis, which is specialized in enterocyte cells, and displays important differences from related processes in other types of cells. Thus this research will be relevant to nutrient uptake, fluid homeostasis and dysentery, and fetal antibody transport.