Focal adhesion sites and the removal of substratum-bound fibronectin.
Focal adhesion sites and the removal of substratum-bound fibronectin.
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DOI：
10.1083/jcb.103.6.2697
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发表时间：
1986-12
影响因子：
7.8
通讯作者：
Grinnell, F
中科院分区：
文献类型：
--
作者：
Grinnell, F
当成纤维细胞在吸附的纤连蛋白基质上的无血清培养基中扩散时，或当成纤维细胞在共价交联的纤连蛋白基质上的含血清培养基中扩散时，纤连蛋白未从粘着斑部位下方的基质中去除。在这些条件下，140-kD纤连蛋白受体和粘着斑之间存在共定位。得出的结论是，从粘着斑下方去除吸附的纤连蛋白是一个机械过程，需要血清。血清的作用是非特异性的，因为血清可以用同等浓度的血清白蛋白、卵清蛋白或γ球蛋白代替。定量测量表明，孵育介质中蛋白质的存在减弱了纤连蛋白与基质的相互作用，从而使吸附的蛋白质从高应力位点的基质中去除。从基质中去除纤连蛋白后，细胞将这种物质重组成细胞下方的斑块和原纤维，重组后的纤连蛋白与纤连蛋白受体共定位。一些纤连蛋白斑块被吞噬。观察到纤连蛋白原纤维与肌动蛋白丝束对齐，有时易位到细胞表面。有人提出，从粘着斑下方去除纤连蛋白是细胞如何通过收缩活性来修饰其细胞外基质的一个例子。
Fibronectin was not removed from the substratum beneath focal adhesion sites when fibroblasts spread in serum-free medium on adsorbed fibronectin substrata, or when fibroblasts spread in serum-containing medium on covalently cross-linked fibronectin substrata. Under these conditions, there was colocalization between 140-kD fibronectin receptors and focal adhesion sites. It was concluded that removal of adsorbed fibronectin from beneath focal adhesion sites was a mechanical process that required serum. The effect of serum was nonspecific since serum could be replaced by equivalent concentrations of serum albumin, ovalbumin, or gamma globulins. Quantitative measurements indicated that the presence of proteins in the incubation medium weakens the interaction of fibronectin with the substratum, thereby allowing the adsorbed protein to be removed from the substratum at sites of high stress. After removing fibronectin from the substratum, cells reorganized this material into patches and fibrils beneath cells, and the reorganized fibronectin colocalized with fibronectin receptors. Some of the patches of fibronectin were phagocytosed. The fibronectin fibrils were observed to be in register with actin filament bundles and sometimes translocated to the upper cell surfaces. It is proposed that removal of fibronectin from beneath focal adhesion sites is an example of how cells can modify their extracellular matrices through contractile activity.