Abstract

 Cellular distribution of organelles in living cells is achieved via a variety of transport mechanisms, including directed motion, mediated by molecular motors along microtubules (MTs), and diffusion which is predominantly heterogeneous in space. In this paper, we introduce a model for particle transport in elongated cells that couples poleward drift, long-range bidirectional transport and diffusion with spatial heterogeneity in a three-dimensional space. Using stochastic simulations and analysis of a related population model, we find parameter regions where the three-dimensional model can be reduced to a coupled one-dimensional model or even a one-dimensional scalar model. We explore the efficiency with which individual model components can overcome drift towards one of the cell poles to reach an approximately even distribution. In particular, we find that if lateral movement is well mixed, then increasing the binding ability of particles to MTs is an efficient way to overcome a poleward drift, whereas if lateral motion is not well mixed, then increasing the axial diffusivity away from MTs becomes an efficient way to overcome the poleward drift. Our three-dimensional model provides a new tool that will help to understand the mechanisms by which eukaryotic cells organize their organelles in an elongated cell, and in particular when the one-dimensional models are applicable.

Graphic abstract

中文翻译：

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通过异质漂移-扩散和远程传输的协调模拟细长细胞中细胞器的运动

摘要

 活细胞中细胞器的细胞分布是通过多种运输机制实现的，包括由分子马达沿微管 (MT) 介导的定向运动，以及主要在空间中异质性的扩散。在本文中，我们介绍了一个细长细胞中的粒子传输模型，该模型将向极漂移、远程双向传输和扩散与三维空间中的空间异质性相结合。使用相关人口模型的随机模拟和分析，我们找到了可以将三维模型简化为耦合一维模型甚至一维标量模型的参数区域。我们探索了单个模型组件可以克服向单元极之一的漂移以达到近似均匀分布的效率。特别是，我们发现，如果横向运动混合得很好，那么增加粒子与 MTs 的结合能力是克服向极漂移的有效方法，而如果横向运动混合得不好，那么增加远离 MTs 的轴向扩散率成为一种有效的方法克服向极漂移。我们的三维模型提供了一种新工具，有助于理解真核细胞在细长细胞中组织细胞器的机制，特别是当一维模型适用时。

图形摘要