β1-integrin orients epithelial polarity via Rac1 and laminin
β1-integrin orients epithelial polarity via Rac1 and laminin
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DOI：
10.1091/mbc.e04-05-0435
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发表时间：
2005-02-01
影响因子：
3.3
通讯作者：
Zegers, MMP
中科院分区：
文献类型：
--
作者：
Yu, W;Datta, A;Zegers, MMP
上皮细胞因细胞与细胞和细胞与基质的黏附而极化和定向。尽管最近在理解上皮细胞的一般极化机制方面取得了很大进展，但很大程度上还不清楚这种机制是如何受细胞外环境控制的。为了探索细胞-基质相互作用中控制细胞极性取向的信号，我们使用了三维培养系统，在该系统中，Madin-Darby犬肾(MDCK)细胞形成了极化的含腔结构。我们发现，在胶原覆盖极化的MDCK单层后，I型胶原与顶端β1整合素的相互作用诱导了rac1的激活，这是胶原覆盖诱导管囊形成所必需的。囊泡由包裹中央管腔的单层组成，在将单个细胞包埋在胶原蛋白中后形成。在这些培养物中，将β1整合素功能阻断抗体添加到胶原基质中会产生囊泡，这些囊泡在基底膜中层粘连蛋白的组织结构上存在缺陷，并具有反转的极性。激活的rac1的表达或过量的层粘连蛋白-1(LN-1)的加入可以恢复正常的极性。综上所述，我们的结果提示了一条信号通路，在该通路中，β1-内毒素的激活通过一种需要rac1激活和层粘连蛋白组织进入基底膜的机制来定位极化包囊的顶极。
Epithelial cells polarize and orient polarity in response to cell-cell and cell-matrix adhesion. Although there has been much recent progress in understanding the general polarizing machinery of epithelia, it is largely unclear how this machinery is controlled by the extracellular environment. To explore the signals from cell-matrix interactions that control orientation of cell polarity, we have used three-dimensional culture systems in which Madin-Darby canine kidney (MDCK) cells form polarized, lumen-containing structures. We show that interaction of collagen I with apical beta1-integrins after collagen overlay of a polarized MDCK monolayer induces activation of Rac1, which is required for collagen overlay-induced tubulocyst formation. Cysts, comprised of a monolayer enclosing a central lumen, form after embedding single cells in collagen. In those cultures, addition of a beta1-integrin function-blocking antibody to the collagen matrix gives rise to cysts that have defects in the organization of laminin into the basement membrane and have inverted polarity. Normal polarity is restored by either expression of activated Rac1, or the inclusion of excess laminin-1 (LN-1). Together, our results suggest a signaling pathway in which the activation of beta1-intearins orients the apical pole of polarized cysts via a mechanism that requires Rac1 activation and laminin organization into the basement membrane.