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

项目摘要 内吞作用是将货物和fluid从细胞外空间摄取到细胞内的过程； 细胞增多症导致多种疾病，包括癌症、神经退行性变和心脏病。笼状蛋白- 介导性内吞作用(CME)是膜变形过程的一个典型例子，其中多个变量 如预先存在的膜曲率、蛋白质机械引起的膜弯曲、膜张力调节等。 和肌动蛋白介导的力量控制囊泡形成的进程。成像技术的进步最近 导致了追踪CME进展的形态和生化数据集的爆炸性增长。在计算时- 脂质双层的传统模型已经提供了对膜的一般力学的洞察，一种机理和 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。 缺乏对CME进展和稳健性的关注，导致实验进展之间存在差距 在继续医学教育和为纳米医学利用继续医学教育的预测性、机械性框架的研究中。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。 膜张力如何在膜-蛋白相互作用存在的情况下控制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说 膜张力是一个动态量，它在CME的发展过程中进化，以调节能量棒- 与囊泡形成有关的载体。SPECIfiCALLY，首席调查员的工作，由其他fi提供支持 fi已经证实，膜张力通过瞬变不稳定性来控制CME。在这些初步的基础上 fi指出，这项拟议工作的目标是阐明持续医学教育的基本生物物理原理。在建议的 在工作中，我们概述了三个假设和目标，这些假设和目标将使我们能够弥合这一知识差距。AIM 1将测试 认为CME过程中膜-蛋白质相互作用由膜张力动态调节的假说；这 假说将使用新的理论和计算模型进行检验，这些模型将结合mem的能量学-- 膜与蛋白质的相互作用和蛋白质沿膜的平面扩散。预计膜张力 将作为蛋白质相互作用引起的局部膜变形的动态调节器出现。目标2将测试 假设在CME过程中力量的产生依赖于内吞陷窝周围的肌动蛋白组织；这个假设- Esis将致力于发展包含动态和随机肌动蛋白膜的理论模型。 并预测肌动蛋白fi在胞内凹陷周围的时空组织。AIM 3将测试 假设预先存在的膜的曲率可以改变能量图景的进程 CME；将开发使用不同基片初始曲率的模型来检验这一假设。总体而言， 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.