Symmetry breaking in reconstituted actin cortices.
Symmetry breaking in reconstituted actin cortices.
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DOI：
10.7554/elife.01433
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发表时间：
2014-04-29
期刊：
影响因子：
7.7
通讯作者：
Keren K
中科院分区：
文献类型：
--
作者：
Abu Shah E;Keren K
肌动蛋白皮层在细胞分裂、产生和维持细胞极性以及运动中起着关键作用。在所有这些情况下，皮层网络必须打破对称性来产生极性细胞骨架动力学。尽管进行了广泛的研究，但体内调节皮质动力学和诱导对称性破坏的机制仍不清楚。在这里，我们介绍了一个在油包水乳液的内部界面上自组织成动态肌动蛋白皮质的重组系统。在肌球蛋白诱导的皮质肌动蛋白流动的驱动下，这种人工系统经历了自发的对称性破坏，这与许多物种胚胎的初始极化非常相似。我们的体外模型系统概括了肌动蛋白皮层在体内的丰富动态，揭示了皮层形成和对称性破坏的基本生物物理和生化要求。此外，该合成系统为进一步探索人工细胞以实现可移动和分裂的最小模型系统铺平了道路。DOI: http://dx.doi.org/10.7554/eLife.01433.001细胞极其复杂，因为它们必须执行大量的过程。然而，这也使得研究人员很难弄清楚细胞的各个部分是如何工作的。因此，人们对开发简单的人造细胞很感兴趣，这种细胞可以精确地模拟细胞特定部分的行为。细胞的一个重要过程叫做极化。这是细胞的内容物以一种不对称的方式排列自己的地方。极化是许多细胞功能所必需的，在胚胎发育过程中尤其重要，它有助于形成发育中的胚胎的复杂形状。细胞骨架——一种支持细胞并使其移动的动态结构——对极化至关重要。细胞骨架的一个重要部分是肌动蛋白皮层。这是一种薄薄的活性薄片，由一种叫做肌动蛋白的蛋白质的微小细丝组成，这种蛋白质聚集在细胞膜的内表面。肌动蛋白皮层的结构和行为的许多方面尚不清楚。Abu Shah和Keren现在已经开发出一种人工细胞系统，使用被油包围的水滴，可以在真实细胞中复制肌动蛋白皮层的行为。特定成核因子在液滴内表面的定位形成肌动蛋白皮层。人工皮质能够自发的对称性破坏，类似于胚胎细胞在发育过程中的初始极化。这种对称性破坏是由一种叫做肌凝蛋白的分子马达驱动的，它取决于皮层中肌动蛋白网络的连通性。在人造细胞上的实验也排除了其他几种解释对称性破缺的机制。Abu Shah和Keren的工作代表着朝着创造可以移动和分裂的简单人造细胞的目标又迈进了一步。DOI: http://dx.doi.org/10.7554/eLife.01433.002
The actin cortex plays a pivotal role in cell division, in generating and maintaining cell polarity and in motility. In all these contexts, the cortical network has to break symmetry to generate polar cytoskeletal dynamics. Despite extensive research, the mechanisms responsible for regulating cortical dynamics in vivo and inducing symmetry breaking are still unclear. Here we introduce a reconstituted system that self-organizes into dynamic actin cortices at the inner interface of water-in-oil emulsions. This artificial system undergoes spontaneous symmetry breaking, driven by myosin-induced cortical actin flows, which appears remarkably similar to the initial polarization of the embryo in many species. Our in vitro model system recapitulates the rich dynamics of actin cortices in vivo, revealing the basic biophysical and biochemical requirements for cortex formation and symmetry breaking. Moreover, this synthetic system paves the way for further exploration of artificial cells towards the realization of minimal model systems that can move and divide. DOI: http://dx.doi.org/10.7554/eLife.01433.001 Cells are extremely complex because they have to perform a vast number of processes. However, this also makes it difficult for researchers to figure out how the individual parts of the cell work. There is interest, therefore, in developing simple artificial cells that can accurately mimic how specific parts of a cell behave. An important process for a cell is called polarization. This is where the contents of the cell arrange themselves in a way that is not symmetrical. Polarization is necessary for many cellular functions, and is particularly important during embryonic development where it helps to form the complex shape of the developing embryo. The cytoskeleton—a dynamic structure that supports the cell and enables it to move—is crucial for polarization. An important part of the cytoskeleton is the actin cortex. This is a thin active sheet made up of a network of tiny filaments of a protein called actin that assembles at the inner face of the cell membrane. Many aspects of the structure and behavior of the actin cortex are not understood. Abu Shah and Keren have now developed an artificial cell system using aqueous droplets surrounded by oil that can reproduce the behavior of actin cortices in real cells. An actin cortex forms upon the localization of specific nucleation factors at the inner surface of the droplets. The artificial cortices are capable of spontaneous symmetry breaking, similar to the initial polarization in embryonic cells during development. This symmetry breaking is driven by molecular motors called myosins and depends on the connectivity of the actin network in the cortex. Experiments on the artificial cells also rule out several other mechanisms that have been proposed to explain symmetry breaking. The work of Abu Shah and Keren represents a further step towards the goal of creating simple artificial cells that can move and divide. DOI: http://dx.doi.org/10.7554/eLife.01433.002