Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Structure. 2021 May 6;29(5):488-498.e4. doi: 10.1016/j.str.2020.12.014. Epub 2021 Jan 20.
The actin cytoskeleton plays a fundamental role in numerous cellular processes, such as cell motility, cytokinesis, and adhesion to the extracellular matrix. Revealing the polarity of individual actin filaments in intact cells would foster an unprecedented understanding of cytoskeletal processes and their associated mechanical forces. Cryo-electron tomography provides the means for high-resolution structural imaging of cells. However, the low signal-to-noise ratio of cryo-tomograms obscures the high frequencies, and therefore the polarity of actin filaments cannot be directly measured. Here, we developed a method that enables us to determine the polarity of actin filaments in cellular cryo-tomograms. We applied it to reveal the actin polarity distribution in focal adhesions, and show a linear relation between actin polarity and distance from the apical boundary of the adhesion site.
肌动蛋白细胞骨架在许多细胞过程中起着基本作用，如细胞运动、胞质分裂和与细胞外基质的黏附。揭示完整细胞中单个肌动蛋白丝的极性将促进对细胞骨架过程及其相关机械力的空前理解。冷冻电子断层扫描为细胞的高分辨率结构成像提供了手段。然而，冷冻断层扫描的低信噪比掩盖了高频，因此无法直接测量肌动蛋白丝的极性。在这里，我们开发了一种方法，使我们能够确定细胞冷冻断层扫描中肌动蛋白丝的极性。我们将其应用于揭示焦点黏附中的肌动蛋白极性分布，并显示肌动蛋白极性与黏附位点顶边界的距离之间存在线性关系。
