Ruggiero F, Champliaud M F, Garrone R, Aumailley M
Institut de Biologie et Chimie des Protéines, Centre National de la Recherche Scientifique UPR 412, Lyon, France.
Exp Cell Res. 1994 Feb;210(2):215-23. doi: 10.1006/excr.1994.1032.
Acid-soluble and pepsin-treated collagen V were prepared from fetal human bones or human placenta, respectively, to be tested for potential cell adhesion promoting activity. Out of 14 different collagen I-adhering cell lines, 10 showed distinct adhesion to collagen V. In all cases adhesion was followed by spreading. The activities of intact and pepsin-solubilized collagen V were similar, suggesting that the cell binding sites are restricted to the triple-helical domain of the molecules. Cell adhesion was also induced by the unfolded form of collagen V and after separation of the alpha chains by heparin affinity chromatography. Isolated alpha 2(V) chains, rich in RGD sequences, were more efficient than isolated alpha 1(V) chains. However, cell adhesion to native or denatured collagen V did not proceed by the same molecular mechanisms as shown by cell adhesion inhibition experiments. Cell adhesion to native collagen V was insensitive to the presence of RGD-containing synthetic peptides while adhesion to denatured collagen V was inhibited by the peptides. Furthermore, the results strongly suggested a major role for alpha 1 beta 1 and alpha 2 beta 1 integrins in the RGD-independent cell adhesion to native collagen V. These data indicate that collagen V is a specific adhesive substrate for different cell types. It also suggests that distinct sets of RGD-dependent and RGD-independent receptors mediate cell attachment to unfolded and native collagen V, respectively. This mechanism is shared by at least the interstitial collagens I and VI, which supports the hypothesis that when included in the triple-helical conformation of collagens, RGD sequences are either not accessible to cells or exhibit specific conformations recognized by different integrins.
分别从人胎儿骨骼或人胎盘中制备酸溶性和经胃蛋白酶处理的Ⅴ型胶原蛋白，以测试其潜在的促进细胞黏附活性。在14种不同的能黏附Ⅰ型胶原蛋白的细胞系中，有10种对Ⅴ型胶原蛋白表现出明显的黏附。在所有情况下，黏附之后都会发生铺展。完整的和经胃蛋白酶溶解的Ⅴ型胶原蛋白的活性相似，这表明细胞结合位点局限于分子的三螺旋结构域。Ⅴ型胶原蛋白的未折叠形式以及通过肝素亲和层析分离α链后也能诱导细胞黏附。富含RGD序列的分离的α2（Ⅴ）链比分离的α1（Ⅴ）链更有效。然而，细胞对天然或变性Ⅴ型胶原蛋白的黏附所涉及的分子机制与细胞黏附抑制实验所显示的不同。细胞对天然Ⅴ型胶原蛋白的黏附对含RGD的合成肽不敏感，而对变性Ⅴ型胶原蛋白的黏附则被这些肽抑制。此外，结果强烈表明α1β1和α2β1整合素在细胞对天然Ⅴ型胶原蛋白的不依赖RGD的黏附中起主要作用。这些数据表明Ⅴ型胶原蛋白是不同细胞类型的特异性黏附底物。这也表明不同组的依赖RGD和不依赖RGD的受体分别介导细胞与未折叠和天然Ⅴ型胶原蛋白的附着。至少Ⅰ型和Ⅵ型间质胶原也有这种机制，这支持了这样一种假说，即当RGD序列包含在胶原蛋白的三螺旋构象中时，细胞无法接近它们，或者它们呈现出不同整合素识别的特定构象。
