Modeling and analysis of the mechanochemical processes that govern clathrin-mediated endocytosis

项目摘要 内吞作用是从细胞外空间到细胞内的货物和体液的摄取过程;内吞作用的缺陷， 细胞质增多导致包括癌症、神经变性和心脏病在内的多种疾病。网格蛋白- 介导的内吞作用（CME）是膜变形过程的典型实例，其中多个变量 例如预先存在的膜弯曲，由于蛋白质机械引起的膜弯曲，膜张力调节， 和肌动蛋白介导的力量支配的进展水泡。最近，成像技术的进步 导致了追踪CME进展的形态学和生物化学数据集的爆炸。当计算- 脂质双层的功能性建模提供了对膜的一般力学的深入了解， 可以将质膜组成和质膜-细胞骨架相互作用联系起来的预测框架， 缺乏对CME进展和稳健性的认识，导致实验进展之间存在差距 在CME的研究和预测，利用CME纳米医学的机制框架。初步 我们小组的数据表明，膜张力在控制CME的进展中起重要作用。 在存在膜蛋白相互作用的情况下，膜张力如何控制CME的进展， 膜-细胞骨架相互作用？本申请中的大量初步数据支持工作假设 膜张力是一个动态量，随着CME的进展而演变，以调节能量棒- 与水泡形成有关。特别是，主要研究者的工作，得到其他人发现的支持 艾德已经确定膜张力通过突变不稳定性控制CME。基于这些初步的 根据这些发现，拟议工作的目标是阐明CME的基本生物物理原理。拟议 在这项工作中，我们概述了三个假设和目标，这些目标将使我们能够缩小这一知识差距。目标1将测试 CME期间膜蛋白相互作用受膜张力动态调节的假设;这 假设将使用新的理论和计算模型进行测试，这些模型将结合能量学， 膜-蛋白质相互作用和蛋白质沿膜沿着的平面扩散。预计膜张力 将作为局部膜变形的动态调节剂出现，由于蛋白质相互作用。目标2将测试 假设CME期间力的产生取决于内吞凹周围的肌动蛋白组织;这种假设- esis将侧重于理论模型的发展，包括动态和随机肌动蛋白膜 相互作用和预测周围的内吞坑肌动蛋白的时空组织。目标3将测试 假设预先存在的曲率的膜可以修改能源景观的进展， 将开发CME模型，使用不同的基板初始曲率来测试这一假设。统称 在这三个目标中进行的建模工作所提供的见解将提供对膜蛋白如何 膜-细胞骨架相互作用影响CME的进展。

Project Summary Endocytosis is the process of uptake of cargo and fluid from the extracellular space to inside the cell; defects in endo- cytosis contribute to a wide spectrum of diseases including cancer, neurodegeneration, and heart disease. Clathrin- mediated endocytosis (CME) is an archetypal example of a membrane deformation process where multiple variables such as pre-existing membrane curvature, membrane bending due to the protein machinery, membrane tension regula- tion, and actin-mediated forces govern the progression of vesiculation. Advances in imaging technology have recently led to an explosion in morphological and biochemical data sets that track the progression of CME. While computa- tional modeling of lipid bilayers has provided insight into the mechanics of membranes in general, a mechanistic and predictive framework that can relate the plasma membrane composition and plasma membrane-cytoskeleton interac- tions to the progression and robustness of CME is missing, resulting in a gap between the experimental advances in the study of CME and a predictive, mechanistic framework for harnessing CME for nanomedicines. Preliminary data from our group has shown that membrane tension plays an important role in governing the progression of CME. How does membrane tension govern the progression of CME in the presence of membrane-protein interactions and membrane-cytoskeleton interactions? Substantial preliminary data in this application supports the working hypothesis that membrane tension is a dynamic quantity that evolves over the progression of CME to modulate the energy bar- rier associated with vesiculation. Specifically, the work of the principal investigator, supported by findings from others has identified that membrane tension governs CME through a snapthrough instability. Building on these preliminary findings, the goal of the proposed work is to elucidate the fundamental biophysical principles of CME. In the proposed work, we have outlined three hypotheses and aims aims that will enable us to close this knowledge gap. Aim 1 will test the hypothesis that membrane-protein interactions during CME are regulated by membrane tension dynamically; this hypothesis will be tested using new theoretical and computational models that will incorporate the energetics of mem- brane-protein interactions and in-plane diffusion of proteins along the membrane. It is expected that membrane tension will emerge as a dynamic modulator of local membrane deformations due to protein interactions. Aim 2 will test the hypothesis that force generation during CME depends on the actin organization around an endocytic pit; this hypoth- esis will focus on the development of theoretical models that incorporate the dynamic and stochastic actin-membrane interactions and predict the spatio-temporal organization of actin filaments around an endocytic pit. Aim 3 will test the hypothesis that pre-existing curvature of the membrane can modify the energy landscape of the progression of CME; models will be developed to test this hypothesis using different initial curvatures of the substrate. Collectively, the insights provided by the modeling effort conducted in these three aims will provide insight into how membrane-protein and membrane-cytoskeleton interactions affect the progression of CME.