Transforming fundamental biological questions about cell membranes into quantitative experiments using model and cell systems

包括人类在内的哺乳动物都是由细胞构成的。哺乳动物细胞由脂质、胆固醇和蛋白质组成的外膜包围。这三种类型的分子不均匀地分布在细胞的外膜上，据报道这种异质性会影响疾病的过程。然而，科学家们目前对这种异质性如何在细胞膜中产生知之甚少。这个问题和许多其他关于细胞膜的基本问题在完整细胞中解决是不切实际的。因此，该项目将利用更简单，更易处理的膜系统。在第一种情况下，膜将仅由脂质和胆固醇组成。在第二种情况下，膜将衍生自哺乳动物细胞外膜。在这两种情况下，膜将是不均匀的。在这个项目中，研究人员将进行一系列实验，以了解脂质膜内异质性产生的条件。该项目的长期目标是发现脂质膜的基本物理现象，随后将证明其适用于生物细胞膜和生物技术应用。研究人员将通过新闻稿、公开讲座、K-12外联和科学期刊文章在全国范围内传达他们的研究结果的兴奋和相关性。主要研究者将培养研究生和本科生在STEM领域的职业生涯，并将指导STEM教师。膜的行为，即使是相对简单的模型膜，也是非常丰富的。本项目将研究在模型脂质双层和细胞系统衍生的膜中分离成富含特定脂质（和蛋白质）类型的域的膜。该研究的目的是了解什么物理机制使域稳定，什么物理参数区分域从其他膜区域，以及脂质的结构特征是域形成所需的。这项研究是问题驱动的，而不是技术驱动的;将部署一系列工具，包括原子力显微镜对固体支持物上的膜的成像和荧光显微镜对自由漂浮囊泡的成像。

Mammals, including humans, are built out of cells. Mammalian cells are bounded by an outer membrane composed of lipids, cholesterol, and proteins. These three types of molecules are distributed nonuniformly across the cell's outer membrane, and this heterogeneity is reported to influence disease processes. However, scientists currently have little understanding of how this heterogeneity arises in cell membranes. This issue and a host of other fundamental questions about cell membranes are impractical to address in intact cells. As a result, this project will utilize simpler, tractable membrane systems. In the first case, membranes will be composed of only lipids and cholesterol. In the second case, membranes will be derived from mammalian cell outer membranes. In both cases, the membranes will be nonuniform. In this project, the researchers will conduct a series of experiments to understand the conditions underwhich heterogeneity arises within lipid membranes. The long-­term goal of the project is to discover fundamental physical phenomena of lipid membranes that will subsequently prove applicable and relevant to biological cell membranes and to biotechnological applications. The researchers will convey the excitement and relevance of their results nationwide through press releases, public lectures, K-­12 outreach, and scientific journal articles. The principal investigator will train graduate students and undergraduates for careers in STEM fields and will mentor STEM faculty.The behavior of membranes, even of relatively simple model membranes, is remarkably rich.This project will investigate membranes that segregate into domains enriched in specific lipid (and protein) types in both model lipid bilayers and in membranes derived from cell systems. The objective of the research is to understand what physical mechanisms render domains stable, what physical parameters distinguish domains from other membrane regions, and which structural features of lipids are required for domain formation. The research is question-­driven rather than technique-­driven; an array of tools will be deployed including imaging of membranes on solid supports by atomic force microscopy and imaging of free-­floating vesicles by fluorescence microscopy.