Induction of cell scattering by expression of β1 integrins in β1-deficient epithelial cells requires activation of members of the Rho family of GTPases and downregulation of cadherin and catenin function
Induction of cell scattering by expression of β1 integrins in β1-deficient epithelial cells requires activation of members of the Rho family of GTPases and downregulation of cadherin and catenin function
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DOI：
10.1083/jcb.147.6.1325
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发表时间：
1999-12-13
影响因子：
7.8
通讯作者：
Sonnenberg, A
中科院分区：
文献类型：
--
作者：
Gimond, C;van der Flier, A;Sonnenberg, A
黏附受体在控制组织结构和形态发生中起着至关重要的作用，它将细胞相互连接起来，并与周围的细胞外基质(ECM)相连。在这项工作中，我们研究了细胞间黏附分子和β1整合素是如何相互影响的，使用了两个不同的β1缺失细胞系，上皮Ge11和成纤维细胞样GD25细胞。在Ge11和GD25细胞中，表达β1A或胞质剪接变异体β1D均可导致细胞间黏附连接的破坏和细胞散射。在Ge11细胞中，形态变化与闭锁小带(ZO)-1在高细胞融合时从紧密连接重新分布到粘连连接有关。此外?Pi整合素的表达导致肌动蛋白细胞骨架和局灶性接触的戏剧性重组。β1整合素与它们各自的配体的相互作用是向纺锤形成纤维细胞样表型的完全形态转变所必需的。白介素2受体(IL2R)-β1A嵌合体的表达及其与局部黏附的整合也能诱导细胞黏附的破坏和细胞外基质-细胞接触的重组，但不能促进细胞在纤维连接蛋白上的迁移，这表明细胞-细胞黏附的破坏不仅仅是刺激细胞迁移的结果。在Ge11细胞中，β1整合素的表达导致钙粘附素和α-连环素蛋白水平的下降，并伴随着它们从细胞骨架相关部分重新分布到洗涤剂可溶部分，β1整合素对α-连环素蛋白水平的调节可能在细胞形态转变中发挥作用，因为在β1之前在Ge11细胞中过表达α-连环素阻止了细胞间黏附和细胞散射的破坏。此外：使用Rho样GTP酶的生化活性分析，我们表明在Ge11或GD25细胞中表达β1A、β1D或IL2R-β1A可同时激活RhoA和rac1，但不能激活CDc42。此外，显性负性Rad(N17rac1)在β1之前表达时可抑制细胞间黏附的破坏。然而，这三种GTP酶都可能参与了细胞形态的转变，因为N19RhoA、N17rac1或N17Cdc42的表达逆转了细胞的散射，部分恢复了Ge11-beta 1A细胞中基于钙粘附素的黏附。我们的结果表明，β1整合素通过诱导细胞内的分子事件来调节上皮细胞的极性和运动性，这些分子事件涉及α-连环蛋白功能的下调和Rho样G蛋白rac1和RhoA的激活。
Adhesion receptors, which connect cells to each other and to the surrounding extracellular matrix (ECM), play a crucial role in the control of tissue structure and of morphogenesis. In this work, we have studied how intercellular adhesion molecules and beta 1 integrins influence each other using two different beta 1-null cell lines, epithelial GE11 and fibroblast-like GD25 cells. Expression of beta 1A or the cytoplasmic splice variant beta 1D, induced the disruption of intercellular adherens junctions and cell scattering in both GE11 and GD25 cells. In GE11 cells, the morphological change correlated with the redistribution of zonula occluden (ZO)-1 from tight junctions to adherens junctions at high cell confluency. In addition? the expression of pi integrins caused a dramatic reorganization of the actin cytoskeleton and of focal contacts. Interaction of beta 1 integrins,with their respective ligands was required for a complete morphological transition towards the spindle-shaped fibroblast-like phenotype. The expression of an interleukin-2 receptor (IL2R)-beta 1A chimera and its incorporation into focal adhesions also induced the disruption of cadherin-based adhesions and the reorganization of ECM-cell contacts, but failed to promote cell migration on fibronectin, in contrast to full-length beta 1A, This indicates that the disruption of cell-cell adhesion is not simply the consequence of the stimulated cell migration. Expression of beta 1 integrins in GE11 cells resulted in a decrease in cadherin and alpha-catenin protein levels accompanied by their redistribution from the cytoskeleton-associated fraction to the detergent-soluble fraction, Regulation of alpha-catenin protein levels by beta 1 integrins is likely to play a role in the morphological transition, since overexpression of alpha-catenin in GE11 cells before beta 1 prevented the disruption of intercellular adhesions and cell scattering. In addition: using biochemical activity assays for Rho-like GTPases, we show that the expression of beta 1A, beta 1D, or IL2R-beta 1A in GE11 or GD25 cells triggers activation of both RhoA and Rac1, but not of Cdc42. Moreover, dominant negative Rad (N17Rac1) inhibited the disruption of cell-cell adhesions when expressed before beta 1. However, all three GTPases might be involved in the morphological transition, since expression of either N19RhoA, N17Rac1 or N17Cdc42 reversed cell scattering and partially restored cadherin-based adhesions in GE11-beta 1A cells. Our results indicate that beta 1 integrins regulate the polarity and motility of epithelial cells by the induction of intracellular molecular events involving a downregulation of alpha-catenin function and the activation of the Rho-like G proteins Rac1 and RhoA.