Department of Biomedical Sciences, The Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
Exp Cell Res. 2009 Nov 15;315(19):3312-24. doi: 10.1016/j.yexcr.2009.09.022. Epub 2009 Sep 29.
Cell surface integrins are the primary receptors for cell migration on extracellular matrix, and exist in several activation states regulated in part by ectodomain conformation. The alpha9 integrin subunit, which pairs only with beta1, has specific roles in the immune system and may regulate cell migration. Melanoma cells express abundant alpha9beta1 integrin, and its role in cell migration was assessed. Ligands derived from Tenascin-C and ADAM12 supported alpha9beta1 integrin-mediated cell attachment and GTP-Rac dependent migration, but not focal adhesion formation. Manganese ions induced alpha9beta1 integrin- and Rho kinase-dependent focal adhesion and stress fibre formation, suggesting that the activation status of alpha9beta1 integrin was altered. The effect of manganese ions in promoting focal adhesion formation was reproduced by beta1 integrin activating antibody. The alpha9beta1 integrin translocated to focal adhesions, where active beta1 integrin was also detected by conformation-specific antibodies. Focal adhesion assembly was commensurate with reduced cell migration. Endogenous alpha9beta1 integrin-mediated adhesion was sensitive to the PP1 chemical inhibitor and an inhibitor of endosomal vesicle recycling, but not inhibitors of protein kinase C or the small GTPase Rho. Our results demonstrated that although alpha9beta1 integrin can induce and localise to focal adhesions in a high activation state, its intermediate activity state normally supports cell adhesion consistent with migration.
细胞表面整合素是细胞在细胞外基质上迁移的主要受体，存在几种激活状态，部分受细胞外结构域构象调节。仅与β1 亚基结合的α9 整合素亚基在免疫系统中具有特定作用，并且可能调节细胞迁移。黑色素瘤细胞表达丰富的α9β1 整合素，评估了其在细胞迁移中的作用。来源于 Tenascin-C 和 ADAM12 的配体支持α9β1 整合素介导的细胞附着和 GTP-Rac 依赖性迁移，但不支持焦点粘附的形成。锰离子诱导α9β1 整合素和 Rho 激酶依赖性焦点粘附和应力纤维形成，表明α9β1 整合素的激活状态发生了改变。锰离子促进焦点附着形成的作用可被β1 整合素激活抗体重现。α9β1 整合素易位到焦点粘连处，在那里也通过构象特异性抗体检测到活性β1 整合素。焦点附着的组装与细胞迁移减少相称。内源性α9β1 整合素介导的黏附对 PP1 化学抑制剂和内体小泡再循环抑制剂敏感，但对蛋白激酶 C 或小 GTPase Rho 的抑制剂不敏感。我们的研究结果表明，尽管α9β1 整合素可以在高激活状态下诱导并定位于焦点粘连，但它的中间活性状态通常支持与迁移一致的细胞附着。
