Yochelis A, Ebrahim S, Millis B, Cui R, Kachar B, Naoz M, Gov N S
Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 84990, Israel.
Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, 50 South Drive, Bethesda, MD 20892-8027, USA.
Sci Rep. 2015 Sep 3;5:13521. doi: 10.1038/srep13521.
Actin-based cellular protrusions are an ubiquitous feature of cells, performing a variety of critical functions ranging from cell-cell communication to cell motility. The formation and maintenance of these protrusions relies on the transport of proteins via myosin motors, to the protrusion tip. While tip-directed motion leads to accumulation of motors (and their molecular cargo) at the protrusion tip, it is observed that motors also form rearward moving, periodic and isolated aggregates. The origins and mechanisms of these aggregates, and whether they are important for the recycling of motors, remain open puzzles. Motivated by novel myosin-XV experiments, a mass conserving reaction-diffusion-advection model is proposed. The model incorporates a non-linear cooperative interaction between motors, which converts them between an active and an inactive state. Specifically, the type of aggregate formed (traveling waves or pulse-trains) is linked to the kinetics of motors at the protrusion tip which is introduced by a boundary condition. These pattern selection mechanisms are found not only to qualitatively agree with empirical observations but open new vistas to the transport phenomena by molecular motors in general.
基于肌动蛋白的细胞突起是细胞普遍存在的特征，执行从细胞间通讯到细胞运动等各种关键功能。这些突起的形成和维持依赖于蛋白质通过肌球蛋白马达向突起尖端的运输。虽然尖端定向运动导致马达（及其分子货物）在突起尖端积累，但据观察，马达也会形成向后移动、周期性且孤立的聚集体。这些聚集体的起源和机制，以及它们是否对马达的循环利用很重要，仍然是未解之谜。受新型肌球蛋白XV实验的启发，提出了一个质量守恒的反应 - 扩散 - 平流模型。该模型包含马达之间的非线性协同相互作用，使其在活性状态和非活性状态之间转换。具体而言，形成的聚集体类型（行波或脉冲序列）与突起尖端马达的动力学相关，这是由边界条件引入的。发现这些模式选择机制不仅在定性上与实证观察结果一致，而且总体上为分子马达的运输现象开辟了新的视野。
