Arnold Sommerfeld Center for Theoretical Physics (ASC) and Center for NanoScience (CeNS), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstraße 37, D-80333 München, Germany.
Cells. 2020 Jun 23;9(6):1524. doi: 10.3390/cells9061524.
Important cellular processes, such as cell motility and cell division, are coordinated by cell polarity, which is determined by the non-uniform distribution of certain proteins. Such protein patterns form via an interplay of protein reactions and protein transport. Since Turing's seminal work, the formation of protein patterns resulting from the interplay between reactions and diffusive transport has been widely studied. Over the last few years, increasing evidence shows that also advective transport, resulting from cytosolic and cortical flows, is present in many cells. However, it remains unclear how and whether these flows contribute to protein-pattern formation. To address this question, we use a minimal model that conserves the total protein mass to characterize the effects of cytosolic flow on pattern formation. Combining a linear stability analysis with numerical simulations, we find that membrane-bound protein patterns propagate against the direction of cytoplasmic flow with a speed that is maximal for intermediate flow speed. We show that the mechanism underlying this pattern propagation relies on a higher protein influx on the upstream side of the pattern compared to the downstream side. Furthermore, we find that cytosolic flow can change the membrane pattern qualitatively from a peak pattern to a mesa pattern. Finally, our study shows that a non-uniform flow profile can induce pattern formation by triggering a regional lateral instability.
重要的细胞过程，如细胞运动和细胞分裂，是通过细胞极性协调的，细胞极性由特定蛋白质的不均匀分布决定。这种蛋白质模式通过蛋白质反应和蛋白质运输的相互作用形成。自图灵的开创性工作以来，由于反应和扩散运输之间的相互作用而形成的蛋白质模式已被广泛研究。在过去的几年中，越来越多的证据表明，细胞质和皮质流动引起的对流运输也存在于许多细胞中。然而，目前尚不清楚这些流动是如何以及是否有助于蛋白质模式的形成。为了解决这个问题，我们使用了一个保持总蛋白质质量的最小模型来描述细胞质流动对模式形成的影响。我们通过线性稳定性分析和数值模拟相结合，发现膜结合蛋白模式沿着细胞质流动的方向传播，在中等流动速度下速度最快。我们表明，这种模式传播的机制依赖于与下游相比，模式上游的蛋白质流入量更高。此外，我们发现细胞质流动可以通过触发局部横向不稳定性将膜图案从峰图案定性地改变为台面图案。最后，我们的研究表明，非均匀的流动剖面可以通过触发局部横向不稳定性来诱导图案形成。
