The mechanics of F-actin microenvironments depend on the chemistry of probing surfaces
The mechanics of F-actin microenvironments depend on the chemistry of probing surfaces
复制标题
DOI：
10.1016/s0006-3495(00)76558-1
复制
发表时间：
2000-12-01
影响因子：
3.4
通讯作者：
Kuo, SC
中科院分区：
文献类型：
--
作者：
McGrath, JL;Hartwig, JH;Kuo, SC
为了了解肌动蛋白网络的微观力学特性，我们通过控制表面特性来监测嵌入粒子的运动。这些粒子的高分辨布朗运动揭示了它们周围微环境的粘弹性特征。在非交联和高度交联的肌动蛋白网络中，结合f -肌动蛋白的颗粒报告的粘弹性模量与宏观流变学实验确定的模量相当。相比之下，为防止肌动蛋白结合而进行修饰的颗粒具有较弱的微环境，令人惊讶的是，微环境对丝交联的引入不敏感。即使在同一交联凝胶中相邻，肌动蛋白结合颗粒和非结合颗粒的粘弹性模量在低频时（0.5-1.5 rad/s）相差两个数量级，但在高频时（bbb10 (4) rad/s）会收敛。对于所有的粒子化学，电子显微镜和光学显微镜都没有显示f -肌动蛋白的聚集或消耗，因此f -肌动蛋白的微非均质性不能解释非结合粒子的深度穿透（类似于100 nm）。相反，我们假设非结合粒子周围交联的局部耗竭可以解释这一现象。考虑到细胞中细胞器的移动性，我们的研究结果表明，肌动蛋白结合是微环境反映宏观特性所必需的，相反，释放肌动蛋白可以增强颗粒的移动性，而不仅仅是生化解栓的影响。
To understand the microscopic mechanical properties of actin networks, we monitor the motion of embedded particles with controlled surface properties. The highly resolved Brownian motions of these particles reveal the viscoelastic character of the microenvironments around them. In both non-cross-linked and highly cross-linked actin networks, particles that bind F-actin report viscoelastic moduli comparable to those determined by macroscopic rheology experiments. By contrast, particles modified to prevent actin binding have weak microenvironments that are surprisingly insensitive to the introduction of filament cross-links. Even when adjacent in the same cross-linked gel, actin-binding and nonbinding particles report viscoelastic moduli that differ by two orders of magnitude at low frequencies (0.5-1.5 rad/s) but converge at high frequencies (> 10(4) rad/s). For all particle chemistries, electron and light microscopies show no F-actin recruitment or depletion, so F-actin microheterogeneities cannot explain the deep penetration (similar to 100 nm) of nonbinding particles. Instead, we hypothesize that a local depletion of cross-linking around nonbinding particles explains the phenomena. With implications for organelle mobility in cells, our results show that actin binding is required for microenvironments to reflect macroscopic properties, and conversely, releasing actin enhances particle mobility beyond the effects of mere biochemical untethering.