MOLECULAR AND CELL BIOLOGICAL STUDY ON CELLULAR RESPONSE TO MECHANICAL STRESS

应力纤维是维持细胞结构的最重要的细胞骨架成分之一。人们普遍认为，在循环拉伸时，细胞及其应力纤维都会垂直于拉伸方向。然而，使用我们最新开发的拉伸装置，我们最近发现了相反的证据，即内皮细胞中的应力纤维以相对于拉伸方向特定的倾斜角度迅速重排。根据这一发现，我们试图从实验或理论上建立对这种现象的解释。结果表明，在循环变形场中，应力纤维以特定的角度排列，以减小其长度变化。在这个角度上的应力纤维的重新排列可能是由于避免了压缩应力而发生的，并且可以被解释为将机械应力降低到。它们在变形过程中受到影响。这一假设不仅很好地解释了应力纤维在特定倾斜角度下存活的原因，也解释了在循环变形场的其他角度上应力纤维数量减少的原因。此外，理论研究支持循环变形下细胞内应力纤维取向的假说，并将我们的研究从微观层面扩展到宏观层面，即个体人类。从人体细胞的角度出发，骨骼肌收缩运动可被认为是机械应力。我们研究了细胞对耐力运动和阻力运动的反应。

The stress fiber is one of the most prominent cytoskeletal components that contribute to the maintenance of cell architecture. It has generally been believed that upon cyclic stretching, both cells and their stress fibers become perpendicularly aligned to the direction of stretching. However, using our newly developed stretching device, we have recently found the contrary evidence that stress fibers in endothelial cells rapidly become rearranged at a specific oblique angle relative to the direction of stretching. In light of this finding, we attempted to establish the explanation for such a phenomenon either experimentally or theoretically. It was thus revealed that stress fibers align at a particular angle so as to minimize their length alterations in cyclic deforming fields. Rearrangement of the stress fibers at this angle probably occurs as a result of avoiding compressive stress and may be interpreted as a way of reducing the mechanical stress to which. they are subjected during the deformation. This hypothesis explains well the reason not only for the survival of the stress fibers at a particular oblique angle, but also for the reduced numbers of stress fibers found, at the other angles on cyclic deforming fields. Moreover, theoretical study supports this hypothesis of intracellular stress fiber orientation under cyclic deformation.We also expand our study from microscopic level to macroscopic level, that is, individual human being. Exercise with skeletal muscle contraction can be considered to mechanical stress from the standpoint of cells in body. We studied cellular response to both endurance and resistance exercise.