Fibrillin Assembly Requires Fibronectin
Fibrillin Assembly Requires Fibronectin
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DOI：
10.1091/mbc.e08-08-0830
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发表时间：
2009-02-01
影响因子：
3.3
通讯作者：
Reinhardt, Dieter P.
中科院分区：
文献类型：
--
作者：
Sabatier, Laetitia;Chen, Daliang;Reinhardt, Dieter P.
纤维蛋白构成弹性和非弹性细胞外基质中多功能微原纤维的主要骨干。适当的组装机制对这些微原纤维的形成和功能至关重要，在马凡氏综合征和其他纤原性病变等病理情况下，它们的特性往往受到损害。在这里，我们使用人类真皮成纤维细胞来分析依赖于其他基质形成蛋白的纤维蛋白-1的组装。siRNA敲低实验表明，纤维蛋白1的组装严格依赖于细胞外纤维连接蛋白原纤维的存在。在光镜和电镜水平上进行的免疫标记显示，在组装过程的早期阶段，纤连蛋白-1与纤连蛋白原纤维共定位。蛋白结合试验表明纤维连接蛋白与纤维蛋白1、-2和-3的c端区域以及纤维蛋白1的n端区域相互作用。纤维蛋白-2和-3的c端一半具有多聚化的倾向，正如先前在纤维蛋白-1中所显示的那样。所有三种纤维蛋白的c端与纤维连接蛋白作为多聚体而不是作为单体强烈相互作用。图谱研究显示，纤维蛋白和纤维连接蛋白之间的主要结合相互作用涉及结构域FNI6和FNI9之间的胶原/明胶结合区。
Fibrillins constitute the major backbone of multifunctional microfibrils in elastic and nonelastic extracellular matrices. Proper assembly mechanisms are central to the formation and function of these microfibrils, and their properties are often compromised in pathological circumstances such as in Marfan syndrome and in other fibrillinopathies. Here, we have used human dermal fibroblasts to analyze the assembly of fibrillin-1 in dependence of other matrix-forming proteins. siRNA knockdown experiments demonstrated that the assembly of fibrillin-1 is strictly dependent on the presence of extracellular fibronectin fibrils. Immunolabeling performed at the light and electron microscopic level showed colocalization of fibrillin-1 with fibronectin fibrils at the early stages of the assembly process. Protein-binding assays demonstrated interactions of fibronectin with a C-terminal region of fibrillin-1, -2, and -3 and with an N-terminal region of fibrillin-1. The C-terminal half of fibrillin-2 and -3 had propensities to multimerize, as has been previously shown for fibrillin-1. The C-terminal of all three fibrillins interacted strongly with fibronectin as multimers, but not as monomers. Mapping studies revealed that the major binding interaction between fibrillins and fibronectin involves the collagen/gelatin-binding region between domains FNI6 and FNI9.