Université Paris-Saclay, CNRS, LPTMS, Orsay, France.
PMMH, CNRS, ESPCI Paris, PSL University, Sorbonne Université, Université de Paris, Paris, France.
Elife. 2020 Mar 9;9:e51751. doi: 10.7554/eLife.51751.
Bundles of cytoskeletal filaments and molecular motors generate motion in living cells, and have internal structures ranging from very organized to apparently disordered. The mechanisms powering the disordered structures are debated, and existing models predominantly predict that they are contractile. We reexamine this prediction through a theoretical treatment of the interplay between three well-characterized internal dynamical processes in cytoskeletal bundles: filament assembly and disassembly, the attachement-detachment dynamics of motors and that of crosslinking proteins. The resulting self-organization is easily understood in terms of motor and crosslink localization, and allows for an extensive control of the active bundle mechanics, including reversals of the filaments' apparent velocities and the possibility of generating extension instead of contraction. This reversal mirrors some recent experimental observations, and provides a robust criterion to experimentally elucidate the underpinnings of both actomyosin activity and the dynamics of microtubule/motor assemblies in vitro as well as in diverse intracellular structures ranging from contractile bundles to the mitotic spindle.
细胞骨架丝束和分子马达在活细胞中产生运动，其内部结构从非常有序到明显无序不等。驱动无序结构的机制存在争议，现有的模型主要预测它们是收缩性的。我们通过对细胞骨架束中三种特征内部动力学过程之间相互作用的理论处理来重新审视这一预测：丝束的组装和拆卸、马达的附着-脱离动力学以及交联蛋白的动力学。根据马达和交联蛋白的定位，这种自组织很容易理解，并允许对活性束力学进行广泛的控制，包括反转丝束的表观速度，以及产生延伸而不是收缩的可能性。这种反转反映了一些最近的实验观察结果，并提供了一个稳健的标准，用于实验阐明肌动球蛋白活性以及体外和各种细胞内结构（从收缩束到有丝分裂纺锤体）中微管/马达组装的动力学的基础。
