Yoshida Aiko, Sakai Nobuaki, Uekusa Yoshitsugu, Deguchi Katashi, Gilmore Jamie L, Kumeta Masahiro, Ito Shuichi, Takeyasu Kunio
Graduate School of Biostudies, Kyoto University, Yoshida-konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
Genes Cells. 2015 Feb;20(2):85-94. doi: 10.1111/gtc.12204. Epub 2014 Nov 30.
The dynamics of the cell membrane and submembrane structures are closely linked, facilitating various cellular activities. Although cell surface research and cortical actin studies have shown independent mechanisms for the cell membrane and the actin network, it has been difficult to obtain a comprehensive understanding of the dynamics of these structures in live cells. Here, we used a combined atomic force/optical microscope system to analyze membrane-based cellular events at nanometer-scale resolution in live cells. Imaging the COS-7 cell surface showed detailed structural properties of membrane invagination events corresponding to endocytosis and exocytosis. In addition, the movement of mitochondria and the spatiotemporal dynamics of the cortical F-actin network were directly visualized in vivo. Cortical actin microdomains with sizes ranging from 1.7×10(4) to 1.4×10(5) nm2 were dynamically rearranged by newly appearing actin filaments, which sometimes accompanied membrane invaginations, suggesting that these events are integrated with the dynamic regulation of submembrane organizations maintained by actin turnovers. These results provide novel insights into the structural aspects of the entire cell membrane machinery which can be visualized with high temporal and spatial resolution.
细胞膜与膜下结构的动态变化紧密相连，促进了各种细胞活动。尽管细胞表面研究和皮层肌动蛋白研究已揭示了细胞膜和肌动蛋白网络各自独立的机制，但要全面了解活细胞中这些结构的动态变化一直颇具难度。在此，我们使用了原子力显微镜与光学显微镜联用系统，以纳米级分辨率分析活细胞中基于膜的细胞事件。对COS - 7细胞表面进行成像，显示出了与内吞作用和外排作用相对应的膜内陷事件的详细结构特性。此外，还在体内直接观察到了线粒体的移动以及皮层F - 肌动蛋白网络的时空动态变化。大小在1.7×10⁴至1.4×10⁵ nm²之间的皮层肌动蛋白微结构域会因新出现的肌动蛋白丝而动态重排，这些肌动蛋白丝有时会伴随膜内陷，这表明这些事件与由肌动蛋白周转维持的膜下组织的动态调节相互整合。这些结果为整个细胞膜机制的结构方面提供了新的见解，且这些机制能够以高时空分辨率进行可视化。
