Regulation of cell function by mechanical properties of biopolymer networks and lipid bilayers

通过生物聚合物网络和脂质双层的机械特性调节细胞功能

基本信息

批准号：
10380120
负责人：
Paul A Janmey
金额：
$ 53.94万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-04-15 至 2025-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10380120
关键词：
3-Dimensional Actins Affect Area Atherosclerosis Binding Proteins Biochemical Biological Process Biophysics Biopolymers Cell Nucleus Cell membrane Cell physiology Cells Cellular biology Cholesterol Chromatin Cytoplasm Cytoskeleton DNA Development Disease Filament Future Grain Gravitation Intermediate Filament Proteins Lateral Lipid Bilayers Lipids Liquid substance Malignant Neoplasms Mechanical Stress Mechanics Membrane Metabolic Methods Microtubules Modeling Molecular Molecular Structure Motion Movement Nuclear Matrix Organelles Organism Phase Transition Phenotype Phosphatidylinositol 4,5-Diphosphate Phospholipids Physical Chemistry Physics Physiology Polymers Process Property Proteins Reaction Regulation Signal Transduction Spatial Distribution Structure Surface System Testing Thinness Time Tissues Vimentin Work chemical property crosslink extracellular flexibility materials science mechanical properties molecular dynamics nanoscale particle physical model response simulation viscoelasticity

项目摘要

Project Summary Many aspects of cell biology as well as tissue physiology and the proper functioning of organisms are essentially problems in material science. The structures and reactions that enable proper functioning of an organism need to produce movements that are greater than those generated by random Brownian motion. Cells need to build structures that are strong enough to resist gravitational forces as well as the mechanical stresses that are generated by the same molecular structures and cellular assemblies that evolved to generate movement and force. A related problem in soft matter is to understand the physical chemistry and dynamics of the phospholipid bilayer that forms the cell membrane and orchestrates the signals generated at the cell membrane and sent to the interior. This MIRA application combines two physical studies. One is focused on the mechanical properties of purified biopolymer networks, intact cells, and whole tissues. The second involves biophysical and biochemical characterizations of lipid bilayers containing anionic signaling lipids to determine how these lipids distribute in the dynamic membrane and how this organization impacts their control of intracellular protein targets. We have characterized and worked with theorists to explain the striking nonlinear elastic response of semi-flexible polymeric networks, with emphasis on the cytoskeletal intermediate filament protein vimentin, and shown how these physical models help explain cell and tissue mechanism. We have also shown how important viscoelastic properties of the substrate are to cell phenotypes and have developed new materials by which to study them. In membrane studies, we collaborate with molecular dynamics experts to produce a coherent model of the structures and motions of anionic signaling lipids such as PIP2 ranging from the atomic to the molecular, to the macroscopic membrane scale. Biochemical and cellular studies show that the spatial distribution of these lipids in bilayers impacts the way they control cytoskeletal actin assembly at the cytoplasm/membrane interface. Future work will build on these studies in three different areas. We will use our established models of semiflexible networks to determine why vimentin networks, in contrast to those formed by stiffer polymers, become stiffer when compressed, whereas crosslinked actin or microtubules become softer. We will also extend our studies of extracellular polymers and cells to intracellular systems: cytoskeletal networks containing membrane-bounded organelles, and crosslinked DNA or chromatin with the liquid particles and organelles contained in the nuclear matrix. Here we will use our newly developed method to prepare intact metabolically active nuclei surrounded by a thin layer or cytoplasm and a plasma membrane, and determine how the perinuclear vimentin cage influences the structure and mechanical response of the nucleus. Membrane studies will use our previous methods to alter PIP2 distribution in artificial bilayers and isolated cell membranes, to study how similar changes in PIP2 distribution triggered by changes in intracellular Ca2+ or cholesterol affect actin assembly in intact cells. We will also build on the MD simulations of relatively small membrane systems to coarse grain simulations using the essential features identified by current all-atom simulations. These will enable studies of systems that are large enough and followed for sufficient time to produce phase transitions and nano-scale lipid clusters. These models will be used to predict how different PIP2 binding proteins respond to lateral distribution of the lipid and test these ideas biochemically and in cells.

项目概要细胞生物学以及组织生理学和生物体的正常功能的许多方面都是本质上是材料科学的问题。使物质能够正常运作的结构和反应有机体需要产生比随机布朗运动更大的运动。细胞需要构建足够坚固的结构来抵抗重力和机械力由相同的分子结构和细胞组装体产生的应力，这些分子结构和细胞组装体进化为产生运动和力量。软物质的一个相关问题是了解软物质的物理化学和动力学形成细胞膜并协调细胞产生的信号的磷脂双层膜并传送至内部。此 MIRA 应用程序结合了两项物理研究。一是专注于纯化的生物聚合物网络、完整细胞和整个组织的机械性能。第二个涉及含有阴离子信号脂质的脂质双层的生物物理和生化特征确定这些脂质如何在动态膜中分布以及该组织如何影响它们的控制细胞内蛋白质靶标。我们表征了并与理论家合作来解释显着的非线性弹性响应半柔性聚合物网络，重点是细胞骨架中间丝蛋白波形蛋白，以及展示了这些物理模型如何帮助解释细胞和组织机制。我们还表明了其重要性基材的粘弹性特性与细胞表型相关，并开发了新材料研究他们。在膜研究中，我们与分子动力学专家合作，产生一致的阴离子信号脂质（例如 PIP2）的结构和运动模型，范围从原子到分子分子、宏观膜尺度。生化和细胞研究表明，空间这些脂质在双层中的分布影响它们控制细胞骨架肌动蛋白组装的方式细胞质/膜界面。未来的工作将建立在三个不同领域的这些研究的基础上。我们将使用我们已建立的模型半柔性网络来确定为什么波形蛋白网络与由较硬的聚合物形成的网络相比，压缩时变得更硬，而交联肌动蛋白或微管则变得更软。我们也会将我们对细胞外聚合物和细胞的研究扩展到细胞内系统：细胞骨架网络含有膜结合的细胞器，以及与液体颗粒交联的 DNA 或染色质，核基质中含有的细胞器。在这里我们将使用我们新开发的方法来准备完整的代谢活跃的细胞核被薄层或细胞质和质膜包围，并确定核周波形蛋白笼如何影响细胞核的结构和机械反应。膜研究将使用我们之前的方法来改变 PIP2 在人工双层和分离细胞中的分布细胞膜，研究细胞内 Ca2+ 的变化如何引发 PIP2 分布的类似变化或胆固醇影响完整细胞中肌动蛋白的组装。我们还将建立相对较小的 MD 模拟使用当前全原子确定的基本特征将膜系统进行粗粒模拟模拟。这些将使研究足够大并跟踪足够时间的系统产生相变和纳米级脂质簇。这些模型将用于预测如何不同 PIP2 结合蛋白对脂质的横向分布做出反应，并在生化和细胞中测试这些想法。