Simon Camille, Caorsi Valentina, Campillo Clément, Sykes Cécile
Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 75005, Paris, France. Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France.
Phys Biol. 2018 Jul 30;15(6):065004. doi: 10.1088/1478-3975/aad1ab.
The ability of mammalian cells to deform their membrane relies on the action of the cytoskeleton. In particular, the dynamics of the actin cytoskeleton, assembling at the plasma membrane, plays a crucial role in controlling cell shape. Many proteins are involved to ensure proper growth of the actin network at the cell membrane. The detailed structure of this network regulates the force that is necessary for membrane deformation. We address here how the presence of capping proteins, which limit the length of actin filaments and thus affects network topology, influences membrane shape. We use a system of liposomes, activated to polymerize actin at their surface, and placed in a mixture of purified proteins that reconstitutes actin dynamics. Our system also allows the variation of membrane tension by deflating the liposomes. We show that membrane deformations are clearly favored in the presence of capping proteins in the actin network. Moreover, in the absence of capping proteins, membrane deformations appear only when the liposomes are deflated. Our results unveil that the interplay between membrane tension and actin network structure and dynamics governs cell shape.
哺乳动物细胞使细胞膜变形的能力依赖于细胞骨架的作用。特别是，在质膜处组装的肌动蛋白细胞骨架的动力学在控制细胞形状方面起着关键作用。许多蛋白质参与其中，以确保细胞膜处肌动蛋白网络的正常生长。该网络的详细结构调节了膜变形所需的力。我们在此探讨帽蛋白的存在如何影响膜形状，帽蛋白会限制肌动蛋白丝的长度，从而影响网络拓扑结构。我们使用了一种脂质体系统，该系统被激活以在其表面聚合肌动蛋白，并放置在重构肌动蛋白动力学的纯化蛋白质混合物中。我们的系统还允许通过使脂质体放气来改变膜张力。我们表明，在肌动蛋白网络中存在帽蛋白的情况下，膜变形明显更易发生。此外，在没有帽蛋白的情况下，只有当脂质体放气时才会出现膜变形。我们的结果揭示，膜张力与肌动蛋白网络结构和动力学之间的相互作用决定了细胞形状。
