Wu C, Hughes P E, Ginsberg M H, McDonald J A
Department of Biochemistry and Molecular Biology, Samuel C. Johnson Medical Research Center, Mayo Clinic Scottsdale, AZ 85259, USA.
Cell Adhes Commun. 1996 Sep;4(3):149-58. doi: 10.3109/15419069609014219.
Fibronectin matrix assembly is a complex cellular process initiated by specific fibronectin-binding cell surface receptors. Although the integrin alpha 5 beta 1 has been implicated in the assembly of fibronectin matrices, fibroblastic cells derived from alpha 5 integrin null mutant embryos assemble a fibronectin matrix. Thus, alternative receptors must support this process. Although the platelet integrin alpha IIb beta 3 supports fibronectin matrix assembly, its expression is restricted to platelets. We report that alpha v beta 3 integrin, a fibronectin receptor expressed on many cell types provides an alternative pathway for the assembly of soluble fibronectin into the extracellular matrix. This process occurs independent of alpha 5 beta 1, is also modulated by activation, and the resulting matrix is biochemically indistinguishable from that assembled under the control of alpha 5 beta 1. Matrix assembly requires binding to the RGD site in the 10th type III repeat of fibronectin, as well as the participation of the amino-terminal matrix assembly domain. The participation of two distinct integrins in fibronectin matrix assembly suggests a model for the involvement of integrins in a dual system of extracellular matrix assembly and recognition controlled by intracellular activation of extracellular receptors.
纤连蛋白基质组装是一个由特定的纤连蛋白结合细胞表面受体启动的复杂细胞过程。尽管整合素α5β1与纤连蛋白基质的组装有关，但源自α5整合素基因敲除突变胚胎的成纤维细胞仍能组装纤连蛋白基质。因此，必定存在其他受体支持这一过程。尽管血小板整合素αIIbβ3支持纤连蛋白基质组装，但其表达仅限于血小板。我们报告称，αvβ3整合素作为一种在多种细胞类型上表达的纤连蛋白受体，为将可溶性纤连蛋白组装到细胞外基质中提供了一条替代途径。这个过程独立于α5β1发生，也受到激活的调节，并且所形成的基质在生化性质上与在α5β1控制下组装的基质没有区别。基质组装需要与纤连蛋白第10个III型重复序列中的RGD位点结合，以及氨基末端基质组装结构域的参与。两种不同的整合素参与纤连蛋白基质组装，这提示了一种关于整合素参与由细胞外受体的细胞内激活所控制的细胞外基质组装和识别双重系统的模型。
