有丝分裂微管星形细胞负端马达向DNA滑动的集体行为
Collective behavior of minus-ended motors in mitotic microtubule asters gliding towards DNA
摘要：
微管（MT）由中心体成核，形成星形结构，称为星状体。紫菀运动和动力学对于基因组稳定性、细胞分裂、极化和分化至关重要。紫菀要么向细胞中心移动，要么远离细胞中心。在这里，我们集中在非洲爪蟾细胞质卵提取物的膜非依赖性系统的定心机制。使用活显微镜和单粒子跟踪，我们发现，紫苑走向染色质化的DNA结构。的速度和方向性的配置文件表明，一个随机游走与漂移指向DNA。我们已经开发了一个理论模型，可以解释这种运动作为一个梯度的MT长度动态和MT滑动固定动力蛋白电机的结果。在模拟中，运动种类对MT的径向阵列的拮抗作用导致纯粹由于几何考虑的拔河，并且aster运动类似于定向随机行走。此外，我们的模型预测，星的速度不会随着DNA的初始距离的变化而变化很大。随着运动密度的增加，不对称紫苑的运动变得越来越超扩散，但对于对称紫苑，它变得不那么超扩散。对称星从超扩散到扩散流动性的转变是拔河比赛中束缚马达数量波动的结果。总的来说，我们的模型是在非洲爪蟾细胞质提取物的实验数据，并预测电机MT相互作用的集体效应的新功能。
英文摘要：
Microtubules (MTs) nucleated by centrosomes form star-shaped structures referred to as asters. Aster motility and dynamics is vital for genome stability, cell division, polarization and differentiation. Asters move either towards the cell center or away from it. Here, we focus on the centering mechanism in a membrane independent system of Xenopus cytoplasmic egg extracts. Using live microscopy and single particle tracking, we find that asters move towards chromatinized DNA structures. The velocity and directionality profiles suggest a random walk with drift directed towards DNA. We have developed a theoretical model that can explain this movement as a result of a gradient of MT length dynamics and MT gliding on immobilized dynein motors. In simulations, the antagonistic action of the motor species on the radial array of MTs leads to a tug-of-war purely due to geometric considerations and aster motility resembles a directed random-walk. Additionally our model predicts that aster velocities do not change greatly with varying initial distance from DNA. The movement of asymmetric asters becomes increasingly super-diffusive with increasing motor density, but for symmetric asters it becomes less super-diffusive. The transition of symmetric asters from superdiffusive to diffusive mobility is the result of number fluctuations in bound motors in the tug-of-war. Overall, our model is in good agreement with experimental data in Xenopus cytoplasmic extracts and predicts novel features of the collective effects of motor-MT interactions.
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