| 摘要: | 多細胞生物中，細胞爬行參與胚胎演化、傷口癒合等重要的生物過程。爬行時，細胞對稱性消失(極化)，並且藉由馬達蛋白的驅動、細胞骨架的聚合(解聚)、以及細胞前端新 (後端舊) 的黏著形成(消失)，周期性的伸出前端的突觸、收回後方的尾肢，向前移動。此稱之為纖維母細胞運動。大多數的研究多著重於解釋細胞極化、伸出突觸的過程，但對其尾肢的收縮機制卻不清楚，且顯少受到關注。在此工作中，我們藉由體外實驗，觀察培養於纖維網蛋白塗層上的狗腎臟外皮細胞(MDCK)，並且藉由活體或固定之肌動蛋白螢光染色，探討細胞尾肢之收縮機制。經由觀察，尾肢的收縮呈現粘滑運動。這可以藉由細胞黏著的輸送帶機制與鬆脫來解釋。根據外型，細胞的尾肢可以分為粗、細兩種。此外，在細尾肢的滑動運動中，其呈現腫凸、彎曲、漂移、斷裂等形態變化，顯示尾肢內物質的分布不均與黏彈性。另一方面，藉由螢光標記，可以得知尾肢的細胞骨架結構。在收縮時，尾肢內物質有壅塞的現象發生。最後，綜上所述，我們認為，肌動蛋白束與細胞黏著間不同的分解程度、與內部物質的壅塞，導致在收縮過程中，不同的尾肢型態變化。;Cell migration in multicellular organism participate embryonic development, wound healing, and several other important biological processes. In the beginning of migration, the cell polarize itself and then repeatedly extends its protrusion and retracts its rear tail, through motor driving, cytoskeleton polymerization (depolymerization), and the formation (releasing) of new front (old back) focal adhesions on the substrate, called fibroblast motion. Most of the studies focused on the process of polarization and protrusion, but the generic mechanism of tail retraction is still unclear. In our work, this elusive issue is experimentally investigated in vitro using MDCK cells on the fibronectin coated substrate, and the cytoskeleton structure of cells are labeled in live and fixed staining. On the basis of our analysis, the retraction tail exhibits stick-slip motion which is caused by tread-milling mechanism and releasing of focal adhesions respectively. Base on morphology, those tails can be classified into fat and narrow types. During the slipping motion, the shape of narrow tails exist bulging, wiggling, drifting, and breaking events, which imply the uneven distribution along the tail, and viscoelastic property. The fluorescence actin staining shows the retracting structure of tail, and jamming events of intercellular transportation. Finally, we propose that the different morphology evolutions during cell tail retraction are dominated by the jamming of inner material, and relatively decomposition rate of focal adhesions and actin filament bundles. |
