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

项目概要 内吞作用是将货物和液体从细胞外空间摄取到细胞内部的过程；内缺陷 细胞增多症会导致多种疾病，包括癌症、神经变性和心脏病。网格蛋白- 介导的内吞作用（CME）是膜变形过程的典型例子，其中多个变量 例如预先存在的膜曲率、由于蛋白质机械导致的膜弯曲、膜张力调节 和肌动蛋白介导的力量控制囊泡的进展。近年来成像技术的进步 导致追踪 CME 进展的形态学和生化数据集激增。虽然计算 脂质双层的模拟模型提供了对一般膜力学的深入了解，这是一种机械和 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 缺少对 CME 进展和稳健性的关注，导致实验进展之间存在差距 研究 CME 以及利用 CME 进行纳米医学的预测、机制框架。初步 我们小组的数据表明，膜张力在控制 CME 的进展中起着重要作用。 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 的进展而变化，以调节能量棒- 与水泡相关的 rier。具体来说，主要研究者的工作得到其他人的研究结果的支持 已经确定膜张力通过突袭不稳定性控制 CME。在此基础上 根据研究结果，拟议工作的目标是阐明 CME 的基本生物物理原理。在提议的 在工作中，我们概述了三个假设和目标，这将使我们能够缩小这一知识差距。目标 1 将进行测试 CME 过程中膜蛋白相互作用受膜张力动态调节的假设；这个 假设将使用新的理论和计算模型进行测试，该模型将结合记忆的能量学 膜-蛋白质相互作用和蛋白质沿膜的平面内扩散。预计膜张力 由于蛋白质相互作用，它将成为局部膜变形的动态调节剂。目标 2 将测试 假设 CME 过程中力的产生取决于内吞坑周围的肌动蛋白组织；这个假设—— esis将重点开发结合动态和随机肌动蛋白膜的理论模型 相互作用并预测内吞坑周围肌动蛋白丝的时空组织。目标 3 将进行测试 假设膜的预先存在的曲率可以改变进展的能量景观 继续医学教育；将开发模型来使用基材的不同初始曲率来测试这一假设。总的来说， 在这三个目标中进行的建模工作所提供的见解将深入了解膜蛋白如何 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.