Mapping the dynamics of shear stress-induced structural changes in endothelial cells
Mapping the dynamics of shear stress-induced structural changes in endothelial cells
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DOI：
10.1152/ajpcell.00457.2006
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发表时间：
2007-11-01
影响因子：
5.5
通讯作者：
Helmke, Brian P.
中科院分区：
文献类型：
--
作者：
Mott, Rosalind E.;Helmke, Brian P.
血流动力学切应力调节内皮细胞的生化过程，该生化过程控制细胞骨架的收缩、局部黏附动力学和细胞外基质(ECM)的组装。由于剪应力导致细胞骨架中离散位置的快速应变集中，我们假设剪应力在几分钟的时间尺度上协调改变细胞骨架、焦点粘连部位和细胞外基质的结构动力学。使用多波长四维荧光显微镜，我们测量了在稳定的单向切应力开始前后，罗丹明-纤维连接蛋白和绿色荧光蛋白标记的肌动蛋白、波形蛋白、帕西林和/或纽蛋白在主动脉内皮细胞中的位移。在细胞骨架中，剪应力增加了肌动蛋白聚合成片状脂膜，改变了肌动蛋白应力纤维和波形蛋白细丝的侧向位移角度，减少了亚融合和融合细胞层肌动蛋白应力纤维的向心性重塑。剪切应力诱导了新的焦点复合体的形成，并减少了新的肌动蛋白聚合区焦点粘连的向心性重塑。局灶性粘连和纤维连接蛋白基质的结构动力学随细胞密度的不同而变化。在亚融合细胞层，剪应力的开始减少了局灶性粘连和纤维连接蛋白纤维的移位。在融合单层中，在切应力开始后1min内，纤维连接蛋白和粘着斑位移的方向明显向下游方向移动。这些细胞骨架、局灶性粘连和细胞外基质的结构动力学在空间上的协调快速变化与剪应力介导的机械转导主要部位附近的机械应力和/或应变的集中一致。
Hemodynamic shear stress regulates endothelial cell biochemical processes that govern cytoskeletal contractility, focal adhesion dynamics, and extracellular matrix (ECM) assembly. Since shear stress causes rapid strain focusing at discrete locations in the cytoskeleton, we hypothesized that shear stress coordinately alters structural dynamics in the cytoskeleton, focal adhesion sites, and ECM on a time scale of minutes. Using multiwavelength four-dimensional fluorescence microscopy, we measured the displacement of rhodamine-fibronectin and green fluorescent protein-labeled actin, vimentin, paxillin, and/or vinculin in aortic endothelial cells before and after onset of steady unidirectional shear stress. In the cytoskeleton, the onset of shear stress increased actin polymerization into lamellipodia, altered the angle of lateral displacement of actin stress fibers and vimentin filaments, and decreased centripetal remodeling of actin stress fibers in subconfluent and confluent cell layers. Shear stress induced the formation of new focal complexes and reduced the centripetal remodeling of focal adhesions in regions of new actin polymerization. The structural dynamics of focal adhesions and the fibronectin matrix varied with cell density. In subconfluent cell layers, shear stress onset decreased the displacement of focal adhesions and fibronectin fibrils. In confluent monolayers, the direction of fibronectin and focal adhesion displacement shifted significantly toward the downstream direction within 1 min after onset of shear stress. These spatially coordinated rapid changes in the structural dynamics of cytoskeleton, focal adhesions, and ECM are consistent with focusing of mechanical stress and/or strain near major sites of shear stress-mediated mechanotransduction.