Roles of Integrins of Endothelial Cells in Response to Mechanical Stimuli

为了阐明内皮细胞对机械刺激的反应机制，利用共聚焦激光扫描显微镜精确观察了肌动蛋白丝和整合素的动态变化。将GFP-actin和RFP-FAT（focal adhesion targeting）载体分别转染培养的内皮细胞，施加剪切力、基底膜张力和静水压力等机械刺激，得到以下结论：1.将GFP-actin和RFP-FAT（focal adhesion targeting）载体转染培养的内皮细胞，施加剪切力。肌动蛋白丝被认为是感受张力并发生动态变化的第一步。第二阶段为板状伪足的形成。在此过程中，整合素的运动和分配可能是通过微管来控制的。2.将内皮细胞培养在浸没有盖玻片的硅橡胶膜上，形成不均匀的应变分布。将细胞暴露于非均匀应变下，发现肌动蛋白丝的分布和细胞核的位置依赖于应变分布。3.培养的内皮细胞对静水压有反应，表现为细胞呈多层结构，细胞伸长，无明显的取向，肌动蛋白丝呈特征性分布。为了阐明其机制，我们集中研究了作为粘附细胞的重要蛋白的VE-钙粘蛋白的表达和分布。提示静水压对VE-cadherin的表达有重要影响。

In order to elucidate the response mechanisms of endothelial cells to mechanical stimuli, dynamic changes in actin filaments and integrins were precisely observed using confocal laser scanning microscopy. Shear stress, membrane tension of substrate and hydrostatic pressure as mechanical stimuli were applied to cultured endothelial cells and the following conclusions were obtained.1.GFP-actin and RFP-FAT (focal adhesion targetting) vectors were transfected into cultured endothelial cells that were used to impose to shear stress. Actin filament was suggested to sense the tension and occur the dynamic changes as the first step. Secondly the lamellipodia were formed. During this process, it was suggested that the movement and allocation of integrins are possible to be controlled through microtubules.2.Endothelial cells were cultured on silicone membrane in which a cover glass was immersed to form heterogeneous strain distribution. A cell was exposed to non-uniform strain and showed that distribution of actin filaments and the location of nucleus was dependent on the strain distribution. It was suggested that the cell is able to sense mechanical stress and respond so as to keep the mechanical balance in the cell.3.We have reported the cultured endothelial cells respond to the hydrostatic pressure and show multilayering, cell elongation with no predominant orientation and characteristic distribution of actin filaments. To elucidate the mechanisms, we have focused on expression and distribution of VE-cadherin as an important protein to adhere the cells. It was suggested that the hydrostatic pressure has important effect on the expression of VE-cadherin.