Verma Deepika, Meng Fanjie, Sachs Frederick, Hua Susan Z
b Department of Mechanical and Aerospace Engineering ; SUNY-Buffalo ; Buffalo , NY USA.
a Department of Physiology and Biophysics ; SUNY-Buffalo , Buffalo , NY USA.
Cell Adh Migr. 2015;9(6):432-40. doi: 10.1080/19336918.2015.1089379.
Cells respond to fluid shear stress through dynamic processes involving changes in actomyosin and other cytoskeletal stresses, remodeling of cell adhesions, and cytoskeleton reorganization. In this study we simultaneously measured focal adhesion dynamics and cytoskeletal stress and reorganization in MDCK cells under fluid shear stress. The measurements used co-expression of fluorescently labeled paxillin and force sensitive FRET probes of α-actinin. A shear stress of 0.74 dyn/cm(2) for 3 hours caused redistribution of cytoskeletal tension and significant focal adhesion remodeling. The fate of focal adhesions is determined by the stress state and stability of the linked actin stress fibers. In the interior of the cell, the mature focal adhesions disassembled within 35-40 min under flow and stress fibers disintegrated. Near the cell periphery, the focal adhesions anchoring the stress fibers perpendicular to the cell periphery disassembled, while focal adhesions associated with peripheral fibers sustained. The diminishing focal adhesions are coupled with local cytoskeletal stress release and actin stress fiber disassembly whereas sustaining peripheral focal adhesions are coupled with an increase in stress and enhancement of actin bundles. The results show that flow induced formation of peripheral actin bundles provides a favorable environment for focal adhesion remodeling along the cell periphery. Under such condition, new FAs were observed along the cell edge under flow. Our results suggest that the remodeling of FAs in epithelial cells under flow is orchestrated by actin cytoskeletal stress redistribution and structural reorganization.
细胞通过涉及肌动球蛋白和其他细胞骨架应力变化、细胞黏附重塑以及细胞骨架重组的动态过程对流体剪切应力作出反应。在本研究中，我们在流体剪切应力作用下同时测量了MDCK细胞中的粘着斑动态以及细胞骨架应力和重组情况。测量使用了荧光标记的桩蛋白和α - 辅肌动蛋白的力敏感FRET探针的共表达。0.74达因/平方厘米的剪切应力作用3小时导致细胞骨架张力重新分布以及显著的粘着斑重塑。粘着斑的命运由相连的肌动蛋白应力纤维的应力状态和稳定性决定。在细胞内部，成熟的粘着斑在流动下35 - 40分钟内解体，应力纤维瓦解。在细胞周边附近，垂直于细胞周边锚定应力纤维的粘着斑解体，而与周边纤维相关的粘着斑持续存在。逐渐减少的粘着斑与局部细胞骨架应力释放和肌动蛋白应力纤维解体相关联，而持续存在的周边粘着斑与应力增加和肌动蛋白束增强相关联。结果表明，流动诱导的周边肌动蛋白束的形成沿着细胞周边为粘着斑重塑提供了有利环境。在这种情况下，在流动下沿着细胞边缘观察到了新的粘着斑。我们的结果表明，上皮细胞在流动下粘着斑的重塑是由肌动蛋白细胞骨架应力重新分布和结构重组精心安排的。
