ESPCI Paris, PSL Research University, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, Physique et Mécanique des Milieux Hétérogénes, UMR 7636, Paris, 75005, France.
Technical University of Denmark, Department of Energy of Conversion and Storage, Roskilde, Denmark.
Sci Rep. 2017 Nov 16;7(1):15688. doi: 10.1038/s41598-017-15638-5.
We measured mechanical properties and dynamic assembly of actin networks with a new method based on magnetic microscopic cylinders. Dense actin networks are grown from the cylinders' surfaces using the biochemical Arp2/3-machinery at play in the lamellipodium extension and other force-generating processes in the cell. Under a homogenous magnetic field the magnetic cylinders self-assemble into chains in which forces are attractive and depend on the intensity of the magnetic field. We show that these forces, from piconewtons to nanonewtons, are large enough to slow down the assembly of dense actin networks and controlled enough to access to their non linear mechanical responses. Deformations are measured with nanometer-resolution, well below the optical resolution. Self-assembly of the magnetic particles into chains simplifies experiments and allows for parallel measurements. The combination of accuracy and good throughput of measurements results in a method with high potential for cell and cytoskeleton mechanics. Using this method, we observed in particular a strong non linear mechanical behavior of dense branched actin networks at low forces that has not been reported previously.
我们使用一种新的基于磁性微圆柱的方法来测量肌动蛋白网络的力学性能和动态组装。致密的肌动蛋白网络从圆柱表面生长，使用的是在片状伪足延伸和细胞中其他产生力的过程中起作用的生化 Arp2/3 机制。在均匀磁场下，磁性圆柱会自组装成链状，其中的力是吸引力，并取决于磁场的强度。我们表明，这些力从皮牛顿到纳牛顿不等，足以减缓致密肌动蛋白网络的组装速度，并且足够精确以访问其非线性力学响应。变形以纳米分辨率测量，远低于光学分辨率。磁性颗粒自组装成链状简化了实验，并允许进行并行测量。测量的准确性和高通量相结合，使该方法在细胞和细胞骨架力学方面具有很大的潜力。使用这种方法，我们特别观察到在低力下密集分支的肌动蛋白网络具有以前未报道过的强非线性力学行为。
