Jensen Mikkel H, Morris Eliza J, Goldman Robert D, Weitz David A
a School of Engineering and Applied Sciences ; Harvard University ; Cambridge , Massachusetts USA.
Bioarchitecture. 2014;4(4-5):138-43. doi: 10.4161/19490992.2014.989035.
The semiflexible polymers filamentous actin (F-actin) and intermediate filaments (IF) both form complex networks within the cell, and together are key determinants of cellular stiffness. While the mechanics of F-actin networks together with stiff microtubules have been characterized, the interplay between F-actin and IF networks is largely unknown, necessitating the study of composite networks using mixtures of semiflexible biopolymers. We employ bulk rheology in a simplified in vitro system to uncover the fundamental mechanical interactions between networks of the 2 semiflexible polymers, F-actin and vimentin IF. Surprisingly, co-polymerization of actin and vimentin can produce composite networks either stronger or weaker than pure F-actin networks. We show that this effect occurs through steric constraints imposed by IF on F-actin during network formation and filament crosslinking, highlighting novel emergent behavior in composite semiflexible networks.
半柔性聚合物丝状肌动蛋白（F-肌动蛋白）和中间丝（IF）都在细胞内形成复杂网络，并且共同构成细胞硬度的关键决定因素。虽然F-肌动蛋白网络与刚性微管的力学特性已得到表征，但F-肌动蛋白网络与IF网络之间的相互作用在很大程度上尚不清楚，因此有必要使用半柔性生物聚合物混合物来研究复合网络。我们在一个简化的体外系统中采用本体流变学方法，以揭示两种半柔性聚合物（F-肌动蛋白和波形蛋白IF）网络之间的基本力学相互作用。令人惊讶的是，肌动蛋白和波形蛋白的共聚可产生比纯F-肌动蛋白网络更强或更弱的复合网络。我们表明，这种效应是通过IF在网络形成和细丝交联过程中对F-肌动蛋白施加的空间位阻约束而产生的，突出了复合半柔性网络中的新型涌现行为。
