Composition, sorting, and morphology of the apical plasma membrane in epithelial cells.

上皮细胞顶端质膜的组成、分类和形态。

基本信息

批准号：
10386333
负责人：
Carolyn Renee Shurer
金额：
$ 6.76万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-12-23 至 2024-12-22
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10386333
关键词：
Achievement Address Affect Affinity Apical Automobile Driving Behavior Binding Binding Proteins Biogenesis Biological Process Biology Biophysics Cell Separation Cell membrane Cells Cellular Membrane Cholesterol Cilia Client Complement Development Diffusion Elements Embryonic Development Engineering Epithelial Epithelial Cells Extracellular Space Family Formulation Galactose Binding Lectin Generations Glycocalyx Glycolipids Glycoproteins Goals Homeostasis Human body Imaging Techniques Integral Membrane Protein Knowledge Lateral Lectin Lipids Maintenance Mass Spectrum Analysis Mediating Membrane Membrane Biology Membrane Lipids Membrane Microdomains Membrane Proteins Methods Molecular Morphogenesis Morphology Mucins Nature Organelles Phase Phenotype Physiological Polysaccharides Post-Translational Protein Processing Process Property Protein Engineering Protein Sorting Signals Protein Sortings Proteins Regulation Role Shapes Signal Transduction Sorting - Cell Movement Sphingolipids Structure Surface System Testing Tissues Transmembrane Domain Uncertainty Vesicle Work apical membrane basolateral membrane biophysical properties cellular microvillus crosslink driving force environmental enrichment for laboratory animals experimental study extracellular fluidity glycosylation insight lipidome lipidomics membrane biogenesis organizational structure polarized cell prevent saturated fat sugar trafficking uptake wound healing

项目摘要

Project Summary Epithelial cell polarization is an essential biological process, serving many physiological roles including tissue morphogenesis and wound healing. A defining feature of polarization is the separation of cell plasma membrane (PM) lipids and proteins into apical and basolateral compartments between which molecular exchange is restricted. Decades ago, the apical PM was found to be enriched in saturated lipids, glycolipids, and cholesterol. Mechanistic hypotheses to explain the biogenesis and unique composition of the apical PM include self- assembling membrane domains (i.e., lipid rafts), specific protein sorting motifs, and post-translational modifications mediating protein sorting. However, neither the detailed composition nor the mechanisms of protein and lipid sorting between PM domains in epithelial cells have been resolved. The lipid profile of the basolateral PM remains unresolved, leaving doubts about the differentiation and lipid separation of the apical and basolateral PM. The general determinants of protein sorting are poorly understood, with past studies focusing on either specific proteins or trafficking machinery. Importantly, the apical PM hosts an extensive extracellular glycocalyx consisting of glycolipids, glycoproteins, and polysaccharides, which can be crosslinked by sugar binding proteins called lectins natively present in the extracellular space. The role of these glycocalyx molecules on protein sorting has not been revealed, despite a major fraction of apical proteins being glycosylated. Finally, the apical PM of polarized epithelia takes on highly outward-curved membrane shapes such as cilia or microvilli, but must also be simultaneously capable of forming inward membrane invaginations for cell signaling and uptake from the extracellular space. The driving forces for the formation of these highly-curved membrane structures remain undetermined. We will investigate these knowledge gaps in membrane and epithelial biology. In Aim 1, we will use advanced lipidomics and imaging techniques to characterize the changes in lipid organization, membrane composition, and membrane properties during the cellular polarization process. We hypothesize that the apical PM will be enriched in highly saturated lipids and glycolipids relative to the basolateral PM, with apical PM biophysical properties reflecting a raft-enriched environment. In Aim 2, we will systematically evaluate the transmembrane protein structural determinants of apical versus basolateral sorting including transmembrane domain features, protein raft affinity, and glycosylation. We hypothesize that these protein features cooperatively direct protein sorting to the apical PM. In Aim 3, we will explore the role of the apical PM glycocalyx in driving membrane bending. We hypothesize that lectin-mediated interactions control the curvature and organization of membranes. Successful execution of these aims will address several largely open questions in membrane biology about how lipid composition, membrane properties, and protein structural features coordinate to organize composition and structure of the polarized cell PM.

项目概要上皮细胞极化是一个重要的生物过程，具有许多生理作用，包括组织形态发生和伤口愈合。极化的一个决定性特征是细胞质膜的分离 (PM) 脂质和蛋白质进入顶侧和基底侧室，其间进行分子交换受限制的。几十年前，人们发现顶端PM富含饱和脂质、糖脂和胆固醇。解释顶端 PM 的生物发生和独特组成的机制假说包括自组装膜结构域（即脂筏）、特定蛋白质分选基序和翻译后介导蛋白质分选的修饰。然而，无论是蛋白质的详细组成还是机制都没有得到证实。上皮细胞中 PM 结构域之间的脂质分选已得到解决。基底外侧的脂质分布 PM仍未解决，对顶端和基底外侧的分化和脂质分离留下了疑问下午。人们对蛋白质分选的一般决定因素知之甚少，过去的研究集中在特定的蛋白质或贩运机制。重要的是，顶端 PM 拥有广泛的细胞外糖萼由糖脂、糖蛋白和多糖组成，可通过糖结合蛋白交联称为凝集素，天然存在于细胞外空间。这些糖萼分子对蛋白质分选的作用尽管大部分顶端蛋白被糖基化，但尚未被揭示。最后，最高 PM 极化上皮细胞呈现高度向外弯曲的膜形状，例如纤毛或微绒毛，但也必须同时能够形成向内的膜内陷，用于细胞信号传递和从细胞中摄取细胞外空间。这些高度弯曲的膜结构形成的驱动力仍然存在未确定。我们将研究膜和上皮生物学中的这些知识差距。在目标 1 中，我们将使用先进的脂质组学和成像技术来表征脂质组织、膜的变化细胞极化过程中的成分和膜特性。我们假设顶端相对于基底外侧 PM，PM 富含高度饱和的脂质和糖脂，顶端 PM 反映筏丰富环境的生物物理特性。在目标 2 中，我们将系统地评估顶端与基底外侧分选（包括跨膜）的跨膜蛋白结构决定因素结构域特征、蛋白筏亲和力和糖基化。我们假设这些蛋白质具有协同作用直接将蛋白质分选至顶端 PM。在目标 3 中，我们将探讨顶端 PM 糖萼在驱动中的作用膜弯曲。我们假设凝集素介导的相互作用控制着曲率和组织膜。这些目标的成功实现将解决膜领域的几个悬而未决的问题关于脂质成分、膜特性和蛋白质结构特征如何协调组织的生物学极化电池PM的组成和结构。