Davies P F, Robotewskyj A, Griem M L
Department of Pathology, Pritzker School of Medicine, University of Chicago, Illinois 60637.
J Clin Invest. 1994 May;93(5):2031-8. doi: 10.1172/JCI117197.
Focal adhesion sites were observed in cultured endothelial cells by tandem scanning confocal microscopy and digitized image analysis, techniques that provide real-time images of adhesion site area and topography in living cells. Image subtraction demonstrated that in the presence of unidirectional steady laminar flow (shear stress [tau] = 10 dyn/cm2) a substantial fraction of focal adhesion sites remodeled in the direction of flow. In contrast, focal adhesions of control (no flow) cells remodeled without preferred direction. In confluent monolayers subjected to shear stresses of 10 dyn/cm2, cells began to realign in the direction of flow after 7-9 h. This was accompanied by redistribution of intracellular stress fibers, alignment of individual focal adhesion sites, and the coalescence of smaller sites resulting in fewer, but larger, focal adhesions per cell. Cell adhesion, repeatedly calculated in the same cells as a function of the areas of focal contact and the separation distances between membrane and substratum, varied by < 10% during both short (30 min), or prolonged (< or = 24 h), periods of exposure to flow. Consistent with these measurements, the gains and losses of focal adhesion area as each site remodeled were approximately equivalent. When the glass substratum was coated with gelatin, rates of remodeling were inhibited by 47% during flow (tau = 10 dyn/cm2). These studies: (a) reveal the dynamic nature of focal adhesion; (b) demonstrate that these sites at the ablumenal endothelial membrane are both acutely and chronically responsive to frictional shear stress forces applied to the opposite (lumenal) cell surface; and (c) suggest that components of the focal adhesion complex may be mechanically responsive elements coupled to the cytoskeleton.
通过串联扫描共聚焦显微镜和数字化图像分析技术，在培养的内皮细胞中观察到了粘着斑，这些技术能够提供活细胞中粘着斑面积和拓扑结构的实时图像。图像减法显示，在单向稳定层流（剪切应力[τ]=10达因/平方厘米）存在的情况下，相当一部分粘着斑会沿流动方向重塑。相比之下，对照（无流动）细胞的粘着斑重塑没有优先方向。在承受10达因/平方厘米剪切应力的汇合单层细胞中，7 - 9小时后细胞开始沿流动方向重新排列。这伴随着细胞内应力纤维的重新分布、单个粘着斑的排列以及较小粘着斑的合并，导致每个细胞的粘着斑数量减少但尺寸增大。在短时间（30分钟）或长时间（≤24小时）暴露于流动过程中，在同一细胞中反复计算的细胞粘附力，根据粘着接触面积和膜与基质之间的分离距离而变化，变化幅度<10%。与这些测量结果一致，每个粘着斑重塑时粘着斑面积的增加和减少大致相当。当玻璃基质用明胶包被时，流动过程中（τ = 10达因/平方厘米）重塑速率被抑制了47%。这些研究：（a）揭示了粘着斑的动态性质；（b）证明了在无腔面内皮细胞膜处的这些位点对施加于相对（腔面）细胞表面的摩擦剪切应力力既有急性反应又有慢性反应；（c）表明粘着斑复合体的成分可能是与细胞骨架相连的机械反应元件。
