Biomechanics on nano- and micro-mechanical systems in bone cells

骨细胞可以感受机械刺激，但其感受机械刺激并将其转化为细胞内生化信号的机制尚不清楚。本研究的重点是肌动蛋白细胞骨架作为机械感觉系统的功能成分。首先，在成骨细胞中，肌动蛋白应力纤维中的细胞内张力被局部释放，并且发现张力释放的应力纤维被选择性地分解，这表明张力对于应力纤维的稳定性是必不可少的。第二，利用微针对单个细胞施加机械扰动，并利用多重荧光标记技术观察细胞内钙离子共振和膜变形。这些研究结果表明，力学和生物化学因素之间的相互作用将是探索力学感觉机制的关键问题。 ...更多信息 细胞骨架肌动蛋白丝的计算机模拟。首先，使用爬行细胞在基板上，我们研究了时空调控的肌动蛋白丝网络在板状伪足中的机械和生化因素之间的相互作用。对肌动蛋白网络结构应变场的定量分析表明，在平行于爬行方向的板状伪足中存在负增量应变。这一结果表明，生物力学因素，如张力释放的细丝参与调节肌动蛋白丝解聚，从而有助于调节细胞动力学。此外，我们还对单个肌动蛋白丝进行了分子动力学模拟，研究了张力对肌动蛋白丝扭转行为的影响，发现肌动蛋白丝存在张力-扭转耦合行为，其扭转角度依赖于张力本身，表明张力释放引发的解聚可能涉及生物力学和生物化学耦合。少

It is recognized that bone cells can sense mechanical stimuli, however, the mechanism by which cells sense mechanical stimulus and transduce it into intracellular biochemical signals is still not clearly understood. This study focuses on actin cytoskeleton as a functional component in the mechanosensory system. First, intracellular tension in the actin stress fibers was locally released in an osteoblastic cell, and it was found that tension-released stress fibers were selectively disassembled, suggesting that tension is essential for a stability of the stress fibers. Second, mechanical perturbation was applied to a single cell using a microneedle, and the calcium resoponse and membrane deformation were simultaniously observed using multiple fluorescent labeling techniques. These studies suggested that interactions among mechanical and biochemical factors would be key issues to explore detail mechanosensory mechanism.Based on these results, we further conducted an in vitro experiment an … More d in silico simulation for cytoskeletal actin filament. First, using a crawling cells on the substrate, we investigated a spatiotemporal regulation of the actin filament network in the lamellipodium in which the interactions among mechanical and biochemical factors are involved. Quantitative evaluation of the strain field of actin network struture revealed that the presense of negative incremental strains in the lamellipodium whose direction is parallel to the crawling direction. This result suggests that biomechanical factors such as tension release in the filament is involed in the regulation of actin filament depolymerization, thereby contributiong to the regulation of cell dynamics. Furthermore, we conducted a molecular dynamics simulation for a single actin filament to clarify the effect of acting tensile force on the twisting behavior, and we found that the tension-twisting coupling behavior was observed and its twisting angle depends on the tensile force itself, suggesting a biomechanical and biochemical coupling may be involved in the depolymerization initiated by the tension release. Less