Guérin Christophe, N'Diaye Anne-Betty, Gressin Laurène, Mogilner Alex, Théry Manuel, Blanchoin Laurent, Colin Alexandra
Cytomorpholab, Laboratoire de Physiologie Cellulaire and Végétale, Interdisciplinary Research Institute of Grenoble, University of Grenoble-Alpes, CEA, CNRS, INRA, 17 avenue des Martyrs, 38054 Grenoble, France.
Courant Institute of Mathematical Sciences and Department of Biology, New York University, 251 Mercer Street, New York, NY 10012, USA.
Curr Biol. 2025 Feb 3;35(3):500-513.e5. doi: 10.1016/j.cub.2024.11.067. Epub 2025 Jan 9.
In cells, multiple actin networks coexist in a dynamic manner. These networks compete for a common pool of actin monomers and actin-binding proteins. Interestingly, all of these networks manage to coexist despite the strong competition for resources. Moreover, the coexistence of networks with various strengths is key to cell adaptation to external changes. However, a comprehensive view of how these networks coexist in this competitive environment, where resources are limited, is still lacking. To address this question, we used a reconstituted system, in closed microwells, consisting of beads propelled by actin polymerization or micropatterns functionalized with lipids capable of initiating polymerization close to a membrane. This system enabled us to build dynamic actin architectures, competing for a limited pool of proteins, over a period of hours. We demonstrated the importance of protein turnover for the coexistence of actin networks, showing that it ensures resource distribution between weak and strong networks. However, when competition becomes too intense, turnover alone is insufficient, leading to a selection process that favors the strongest networks. Consequently, we emphasize the importance of competition strength, which is defined by the turnover rate, the amount of available protein, and the number of competing structures. More generally, this work illustrates how turnover allows biological populations with various competition strengths to coexist despite resource constraints.
在细胞中，多个肌动蛋白网络以动态方式共存。这些网络竞争肌动蛋白单体和肌动蛋白结合蛋白的共同库。有趣的是，尽管对资源存在激烈竞争，但所有这些网络都能设法共存。此外，不同强度网络的共存是细胞适应外部变化的关键。然而，对于这些网络在资源有限的竞争环境中如何共存，仍缺乏全面的认识。为了解决这个问题，我们使用了一个重构系统，在封闭的微孔中，该系统由通过肌动蛋白聚合推动的珠子或用能够在膜附近引发聚合的脂质功能化的微图案组成。这个系统使我们能够在数小时内构建动态肌动蛋白结构，竞争有限的蛋白质库。我们证明了蛋白质周转对于肌动蛋白网络共存的重要性，表明它确保了资源在弱网络和强网络之间的分配。然而，当竞争变得过于激烈时，仅靠周转是不够的，会导致一个有利于最强网络的选择过程。因此，我们强调竞争强度的重要性，它由周转率、可用蛋白量和竞争结构的数量来定义。更一般地说，这项工作说明了周转如何使具有不同竞争强度的生物群体在资源受限的情况下共存。
