周期性单轴拉伸力学刺激对哺乳动物细胞有丝分裂方向影响的研究

Effects of Cyclic Uniaxial Stretch on Mammalian Cell Division Direction

哺乳动物细胞的有丝分裂过程与细胞的增殖、分化以及生物体发育、组织器官形成、损伤组织的修复和疾病的发生有关.广泛存在的力学刺激能否对细胞有丝分裂方向产生影响,以及其影响有丝分裂定向的途径尚未完全阐明.采用小鼠成纤维细胞作为模型,研究周期性单轴拉伸力学刺激对细胞应力纤维排布和有丝分裂方向的影响.结果表明,周期性单轴拉伸诱导细胞有丝分裂与应力纤维垂直于拉伸方向排布.而阻断应力纤维的两种基本组成成分(微丝和肌球蛋白Ⅱ),会造成在周期性单轴拉伸条件下的应力纤维和有丝分裂方向重排.特别是,Y27632(10μmol/L)和低浓度的ML7(50μmol/L)、Blebbistatin(50μmol/L)可以诱导细胞有丝分裂与应力纤维平行于拉伸方向排布.统计结果表明,在不同实验条件下,应力纤维排布和有丝分裂方向均具有高度相关性.Western blot实验表明,肌球蛋白轻链磷酸化水平与周期性单轴拉伸刺激下的应力纤维排布和有丝分裂方向密切相关.上述结果提示:周期性单轴拉伸力学刺激通过诱导应力纤维的排布,决定了细胞的有丝分裂方向.

Mechanical forces are widely involved in regulating basic cellular functions, including proliferation, differentiation, adhesion, and migration. However, few studies show how the mechanical forces impact cell division direction, a crucial process in development, differentiation, embryogenesis and recovery of tissues. It has been documented that cell division direction is guided by stress fibers, which are cortical cues perpendicular to exogenous cyclic uniaxial stretch. In our study, we used the murine 3T3 fibroblasts as a model, to investigate the effect of uniaxial stretch on stress fiber alignment and cell division direction with custom-made stretch devices. We found that cyclic uniaxial stretch induced stress fiber alignment and cell division direction perpendicularly to the stretch direction. The blockage of actin assembly and myosin 1I, two basic components of stress fibers, resulted in a disoriented cell division under uniaxial stretch, which suggested that the cell division direction was secondary to the stress fiber alignment. Our data suggested that Rho/Rho-kinase/MLC （Myosin Light Chain） and MLCK/MLC pathways were involved in the process of stretch-induced stress fiber alignment and cell division direction. Taken together, the present work demonstrated an important effect of uniaxial stretch on cell division direction via affecting the stress fibers alignment.