Dimensional and mechanical dynamics of active and stable edges in motile fibroblasts investigated by using atomic force microscopy
Dimensional and mechanical dynamics of active and stable edges in motile fibroblasts investigated by using atomic force microscopy
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DOI：
10.1073/pnas.96.3.921
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发表时间：
1999-02-02
影响因子：
11.1
通讯作者：
Radmacher, M
中科院分区：
文献类型：
--
作者：
Rotsch, C;Jacobson, K;Radmacher, M
利用原子力显微镜观察了培养的3 T3成纤维细胞突起边缘和稳定边缘的伸缩动态。这种动力学与早期使用视频显微镜的研究结果密切相似，表明原子力显微镜力映射技术不会明显干扰这些动力学。力扫描允许确定活动边缘和稳定边缘的高度，而活动边缘的轮廓是平坦的，平均高度为0.4-0.8 μ m，稳定边缘在边缘约6 μ m内平滑上升至2-3 μ m。在前缘区域，高度波动高达平均值的50%（SD），远大于稳定边缘;这种波动可能反映了潜在的细胞骨架活性的差异。此外，力映射产生局部杨氏模量或弹性模量（E，皮质刚度）的估计。该刚度将与“皮质张力”有关，对于稳定边缘可以精确计算，在这种情况下近似为12 kPa。前缘的薄度妨碍了E值的精确估计，但在边缘的4 μ m内，它比稳定边缘的E值小得多，稳定边缘的上限为3-5 kPa。虽然不能绝对排除起泡作为一种机制的延伸，数据是一致的肌动蛋白聚合和/或肌球蛋白马达机制，其中的平均材料性能的延伸边缘将是几乎恒定的边缘。由于前缘比稳定缘软，这些数据也与延伸优先发生在皮质张力较低的区域的概念一致。
The atomic force microscope (AFM) was employed to investigate the extension and retraction dynamics of protruding and stable edges of motile 3T3 fibroblasts in culture. Such dynamics closely paralleled the results of earlier studies employing video microscopy that indicated that the AFM force-mapping technique does not appreciably perturb these dynamics, Force scans permitted height determinations of active and stable edges, Whereas the profiles of active edges are flat with average heights of 0.4-0.8 mu m, stable edges smoothly ascend to 2-3 mu m within about 6 mu m of the edge. In the region of the leading edge, the height fluctuates up to 50% (SD) of the mean value, much more than the stable edge; this fluctuation presumably reflects differences in underlying cytoskeletal activity. In addition, force mapping yields an estimate of the local Young's modulus or modulus of elasticity (E, the cortical stiffness). This stiffness will be related to "cortical tension," can be accurately calculated for the stable edges, and is approximate to 12 kPa in this case, The thinness of the leading edge precludes accurate estimation of the E values, but within 4 mu m of the margin it is considerably smaller than that for stable edges, which have an upper limit of 3-5 kPa. Although blebbing cannot absolutely be ruled out as a mechanism of extension, the data are consistent with an actin polymerization and/or myosin motor mechanism in which the average material properties of the extending margin would be nearly constant to the edge. Because the leading edge is softer than the stable edge, these data also are consistent with the notion that extension preferentially occurs in regions of lower cortical tension.