Institute of Molecular Psychology and Life Science Training Facility, Biozentrum, University of Basel, Klingelbergstr. 60/70, CH-4056 Basel, Switzerland.
Dev Biol. 2011 Feb 1;350(1):24-31. doi: 10.1016/j.ydbio.2010.10.026. Epub 2010 Oct 26.
Cell junctions are essential to maintain polarity and tissue integrity. Epithelial cell junctions are composed of distinct sub-compartments that together ensure the strong adhesion between neighboring cells. In Caenorhabditis elegans epithelia, the apical junction (CeAJ) forms a single electron-dense structure, but at the molecular level it is composed of two sub-compartments that function redundantly and localize independently as two distinct but adjacent circumferential rings on the lateral plasma membrane. While investigating the role of the multi PDZ-domain containing protein MAGI-1 during C. elegans epidermal morphogenesis, we found that MAGI-1 localizes apical to both the Cadherin/Catenin (CCC) and AJM-1/DLG-1 (DAC) containing sub-domains. Removal of MAGI-1 function causes a loss of junctional compartmentalization along the lateral membrane and reduces the overall robustness of cell-cell adhesion mediated by either type of cell junctions. Our results suggest that MAGI-1 functions as an "organizer" that ensures the correct segregation of different cell adhesion complexes into distinct domains along the lateral plasma membrane. Thus, the formation of stable junctions requires the proper distribution of the CCC and DAC adhesion protein complexes along the lateral plasma membrane.
细胞连接对于维持极性和组织完整性至关重要。上皮细胞连接由不同的亚区组成，这些亚区共同确保相邻细胞之间的紧密粘附。在秀丽隐杆线虫的上皮细胞中，顶端连接（CeAJ）形成一个单一的电子致密结构，但在分子水平上，它由两个亚区组成，这些亚区冗余地发挥作用，并独立地定位在侧向质膜上两个相邻的但不同的环形区域。在研究多 PDZ 结构域蛋白 MAGI-1 在秀丽隐杆线虫表皮形态发生中的作用时，我们发现 MAGI-1 定位于 Cadherin/Catenin (CCC) 和 AJM-1/DLG-1 (DAC) 包含的亚区的顶端。去除 MAGI-1 的功能会导致沿侧向膜失去连接区隔，并降低由任何一种细胞连接介导的细胞间粘附的整体稳健性。我们的结果表明，MAGI-1 作为一种“组织者”发挥作用，确保不同的细胞粘附复合物沿着侧向质膜正确地分隔成不同的区域。因此，稳定连接的形成需要 CCC 和 DAC 粘附蛋白复合物沿着侧向质膜的正确分布。
