Skalski M, Alfandari D, Darribère T
Equipe Adhesion et Migration Cellulaires, Université P. et M. Curie, CNRS UMR 7622, 9 Quai Saint-Bernard, Paris Cedex 05, 75252, France.
Dev Biol. 1998 Mar 15;195(2):158-73. doi: 10.1006/dbio.1997.8838.
During cleavage of Pleurodeles waltl amphibian embryos, inner cells of the blastocoel roof (presumptive ectodermal and mesodermal cells) organize a fibrillar extracellular matrix (ECM) containing fibronectin on their basal surface by a beta1-integrin-dependent process. This matrix is used as a migratory substrate by mesodermal cells during gastrulation. While alpha5beta1 integrin is expressed on both ectodermal and mesodermal cell surface, we have shown previously that alphav containing integrins are essentially restricted to the surface of mesodermal cells (Alfandari, D., Whittaker, C. A., DeSimone, D. W., and Darribère, T., Dev. Biol. 170, 249-261, 1995). To investigate the function of alphav integrins during gastrulation, we have generated a function blocking antibody directed against the extracellular domain of the Pleurodeles integrin alphav subunit. The antibody did not prevent fibronectin fibril formation, whereas an antibody against the alpha5beta1 integrin did. When injected into the blastocoel, the antibody against integrin alphav subunit perturbed gastrulation and further development in a stage-dependent manner. Developmental defects were correlated to an abnormal positioning of the mesoderm layer. In vitro, the antibody blocked spreading of mesodermal cell to fibronectin or blastocoel roof ECM but not their attachment. In contrast, the antibody directed against the alpha5beta1 integrin inhibited both cell attachment and spreading to the same substrates. We propose that the alpha5beta1 integrin is required for fibronectin assembly into fibrils and mesodermal cell attachment to the blastocoel roof ECM, while the alphav containing integrins are necessary for cell spreading, and possibly migration, on this complex network.
在有尾两栖动物疣螈胚胎的卵裂过程中，囊胚腔顶的内层细胞（预定外胚层和中胚层细胞）通过β1整合素依赖性过程在其基底面组织形成含有纤连蛋白的纤维状细胞外基质（ECM）。在原肠胚形成过程中，这种基质被中胚层细胞用作迁移底物。虽然α5β1整合素在外胚层和中胚层细胞表面均有表达，但我们之前已表明，含αv的整合素基本局限于中胚层细胞表面（Alfandari, D., Whittaker, C. A., DeSimone, D. W., and Darribère, T., Dev. Biol. 170, 249 - 261, 1995）。为了研究原肠胚形成过程中αv整合素的功能，我们制备了一种针对疣螈整合素αv亚基细胞外结构域的功能阻断抗体。该抗体并未阻止纤连蛋白纤维的形成，而针对α5β1整合素的抗体则可以。当注射到囊胚腔中时，针对整合素αv亚基的抗体以阶段依赖性方式干扰原肠胚形成和进一步发育。发育缺陷与中胚层层的异常定位相关。在体外，该抗体阻断中胚层细胞在纤连蛋白或囊胚腔顶ECM上的铺展，但不影响它们的附着。相反，针对α5β1整合素的抗体抑制细胞在相同底物上的附着和铺展。我们提出，α5β1整合素是纤连蛋白组装成纤维以及中胚层细胞附着于囊胚腔顶ECM所必需的，而含αv的整合素对于细胞在这个复杂网络上的铺展以及可能的迁移是必需的。
