Engler Adam J, Chan May, Boettiger David, Schwarzbauer Jean E
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
J Cell Sci. 2009 May 15;122(Pt 10):1647-53. doi: 10.1242/jcs.040824. Epub 2009 Apr 28.
Cells within tissues are surrounded by fibrillar extracellular matrix (ECM) that supports cell adhesion via integrin receptors. The strength of cell interactions with fibrillar matrix and the effects of force on these interactions have not been quantified. To this end, we used a spinning disc device to apply radially increasing shear to human HT1080 fibrosarcoma cells attached to a cell-derived fibrillar fibronectin (FN) matrix. The shear required to detach 50% of HT1080 cells was eight times greater on a FN-coated, rigid glass substrate than on fibrillar FN matrix. Covalent crosslinking of the FN matrix increased its stiffness tenfold and produced a modest increase in shear detachment force for these cells. On FN-coated surfaces, cells detach by releasing interactions between alpha5beta1 integrin and FN. By contrast, cell detachment from fibrillar matrix occurred through a novel mechanism of fibril breakage, which left holes in the matrix visible by fluorescence microscopy. These results show that cells require less force to detach from fibrillar matrix than from FN adsorbed on glass and that detachment occurs through breaking fibrils instead of by release of integrin-matrix bonds. Thus, ECM fibril breakage is another molecular feature to consider when understanding cell and tissue homeostasis.
组织中的细胞被纤维状细胞外基质（ECM）所包围，该基质通过整合素受体支持细胞黏附。细胞与纤维状基质相互作用的强度以及力对这些相互作用的影响尚未得到量化。为此，我们使用了一种旋转盘装置，对附着在细胞衍生的纤维状纤连蛋白（FN）基质上的人HT1080纤维肉瘤细胞施加径向增加的剪切力。在FN包被的刚性玻璃基质上，使50%的HT1080细胞脱离所需的剪切力比在纤维状FN基质上大八倍。FN基质的共价交联使其刚度增加了十倍，并使这些细胞的剪切脱离力适度增加。在FN包被的表面上，细胞通过释放α5β1整合素与FN之间的相互作用而脱离。相比之下，细胞从纤维状基质上的脱离是通过一种新的纤维断裂机制发生的，这使得基质中的孔洞在荧光显微镜下可见。这些结果表明，细胞从纤维状基质上脱离所需的力比从吸附在玻璃上的FN上脱离所需的力小，并且脱离是通过纤维断裂而不是通过整合素-基质键的释放发生的。因此，ECM纤维断裂是理解细胞和组织稳态时需要考虑的另一个分子特征。
