活性弹性二聚体：细胞在刚性轨道上运动
Active elastic dimers: Cells moving on rigid tracks
摘要：
实验表明，某些细胞在三维细胞外基质中的迁移与一维细胞迁移具有很强的相似性。基于这一观察，我们构建并研究了一个由两个珠子和一个沿刚性轨道运动的主动弹簧组成的最小一维模型细胞。主动弹簧模型的应力纤维与肌球蛋白驱动的收缩性和α-辅肌动蛋白驱动的可伸展性，而两个珠子的摩擦系数描述的捕捉/滑动粘结行为的整联蛋白在局灶性粘连。在不存在主动噪声的情况下，净运动起因于应力纤维的主动收缩性（和被动伸展性）与细胞的前部和后部之间的不对称性之间的相互作用，所述不对称性是由于细胞前部处的整联蛋白的捕获结合行为和后部处的整联蛋白的滑动结合行为。我们通过独立估计的参数获得了合理的单元速度。我们还研究了滞后的影响，在主动弹簧，由于捕捉键的行为和动力学的交联，并增加了主动噪声的运动的细胞。我们的模型突出了α-辅肌动蛋白在三维细胞运动中的作用，不需要Arp 2/3肌动蛋白丝成核净运动。
英文摘要：
Experiments suggest that the migration of some cells in the three-dimensional extra cellular matrix bears strong resemblance to one-dimensional cell migration. Motivated by this observation, we construct and study a minimal one-dimensional model cell made of two beads and an active spring moving along a rigid track. The active spring models the stress fibers with their myosin-driven contractility and alpha-actinin-driven extendability, while the friction coefficients of the two beads describe the catch/slip bond behavior of the integrins in focal adhesions. In the absence of active noise, net motion arises from an interplay between active contractility (and passive extendability) of the stress fibers and an asymmetry between the front and back of the cell due to catch bond behavior of integrins at the front of the cell and slip bond behavior of integrins at the back. We obtain reasonable cell speeds with independently estimated parameters. We also study the effects of hysteresis in the active spring, due to catch bond behavior and the dynamics of cross-linking, and the addition of active noise on the motion of the cell. Our model highlights the role of alpha-actinin in three-dimensional cell motility and does not require Arp2/3 actin filament nucleation for net motion.
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