Cavalcanti-Adam Elisabetta Ada, Volberg Tova, Micoulet Alexandre, Kessler Horst, Geiger Benjamin, Spatz Joachim Pius
Max-Planck-Institute for Metals Research, Department of New Materials and Biosystems, Stuttgart, Germany.
Biophys J. 2007 Apr 15;92(8):2964-74. doi: 10.1529/biophysj.106.089730. Epub 2007 Feb 2.
Integrin-mediated adhesion is regulated by multiple features of the adhesive surface, including its chemical composition, topography, and physical properties. In this study we investigated integrin lateral clustering, as a mechanism to control integrin functions, by characterizing the effect of nanoscale variations in the spacing between adhesive RGD ligands on cell spreading, migration, and focal adhesion dynamics. For this purpose, we used nanopatterned surfaces, containing RGD-biofunctionalized gold dots, surrounded by passivated gaps. By varying the spacing between the dots, we modulated the clustering of the associated integrins. We show that cell-surface attachment is not sensitive to pattern density, whereas the formation of stable focal adhesions and persistent spreading is. Thus cells plated on a 108-nm-spaced pattern exhibit delayed spreading with repeated protrusion-retraction cycles compared to cells growing on a 58-nm pattern. Cell motility on these surfaces is erratic and nonpersistent, leaving thin membrane tethers bound to the RGD pattern. Dynamic molecular profiling indicated that the adhesion sites formed with the 108-nm pattern undergo rapid turnover and contain reduced levels of zyxin. These findings indicate that a critical RGD density is essential for the establishment of mature and stable integrin adhesions, which, in turn, induce efficient cell spreading and formation of focal adhesions.
整合素介导的黏附受黏附表面的多种特性调节，包括其化学成分、拓扑结构和物理性质。在本研究中，我们通过表征黏附性RGD配体之间间距的纳米级变化对细胞铺展、迁移和黏着斑动力学的影响，研究整合素侧向聚集作为控制整合素功能的一种机制。为此，我们使用了纳米图案化表面，其包含RGD生物功能化的金点，并被钝化间隙包围。通过改变点之间的间距，我们调节了相关整合素的聚集。我们发现细胞表面附着对图案密度不敏感，而稳定黏着斑的形成和持续铺展则敏感。因此，与在58纳米图案上生长的细胞相比，接种在间距为108纳米图案上的细胞表现出延迟铺展，伴有反复的突出-回缩循环。这些表面上的细胞运动不稳定且不持久，留下与RGD图案结合的薄细胞膜系链。动态分子分析表明，由108纳米图案形成的黏附位点经历快速周转，并且含有较低水平的桩蛋白。这些发现表明，临界RGD密度对于建立成熟且稳定的整合素黏附至关重要，而这反过来又诱导有效的细胞铺展和黏着斑的形成。
