Wang A Z, Ojakian G K, Nelson W J
Institute for Cancer Research, Philadelphia, PA 19111.
J Cell Sci. 1990 Jan;95 ( Pt 1):137-51. doi: 10.1242/jcs.95.1.137.
The development of cell polarity in Madin-Darby canine kidney (MDCK) cells has been analyzed under conditions in which cells are induced to form multicellular epithelial cysts in stages that mimic the ontogeny of epithelial tissues and organs in vivo. The morphogenesis of MDCK cysts in suspension culture or in a collagen gel proceeds in distinct stages involving the initial aggregation of cells followed by development of a closed monolayer of polarized epithelial cells that surrounds a central lumen. The polarity of cells was determined at each stage by analyzing the distributions of marker proteins of the apical (gp135) and basal-lateral (Na+,K(+)-ATPase) domains of the plasma membrane, the tight junction (ZO-1) and proteins involved in cell-cell (uvomorulin) and cell-substratum contact (type IV collagen). We show that cells have a distinctive and opposite polarity in cysts formed in suspension culture compared to those formed in collagen gels. In suspension culture, the basal-lateral membrane faces the central lumen and the apical membrane faces the outside, whereas in collagen gel, the basal-lateral membrane faces the outside collagen and the apical membrane faces the central lumen. Detailed analysis of the distributions of marker proteins during the morphogenesis of these three-dimensional structures indicates that: (1) cell-cell contact is sufficient to trigger the segregation of marker proteins of the apical and basal-lateral membrane domains to distinct regions of the membrane; (2) cell-cell contact induces association of the tight junction protein ZO-1 with the contact zone between cells; (3) localization of the tight junction protein ZO-1 to the apex of the lateral membrane and the establishment of the epithelial axis, however, requires the formation of a basal lamina and cell-substratum contact; (4) in suspension culture, MDCK cysts secrete and establish a basal lamina in the central lumen. These results show that cell-cell and cell-substratum contact have distinct roles in the morphogenesis of polarized epithelia. We suggest that the mechanisms involved in triggering cell polarity may be common to different polarized epithelia in vivo.
在模拟体内上皮组织和器官个体发育阶段诱导细胞形成多细胞上皮囊肿的条件下，对马-达二氏犬肾（MDCK）细胞中细胞极性的发育进行了分析。悬浮培养或胶原凝胶中MDCK囊肿的形态发生分不同阶段进行，包括细胞的初始聚集，随后是围绕中央管腔的极化上皮细胞封闭单层的形成。通过分析质膜顶端（gp135）和基底外侧（Na +，K（+）-ATP酶）结构域、紧密连接（ZO-1）以及参与细胞-细胞（桥粒芯蛋白）和细胞-基质接触（IV型胶原）的标记蛋白的分布，确定每个阶段细胞的极性。我们发现，与胶原凝胶中形成的囊肿相比，悬浮培养中形成的囊肿细胞具有独特且相反的极性。在悬浮培养中，基底外侧膜面向中央管腔，顶端膜面向外部，而在胶原凝胶中，基底外侧膜面向外部胶原，顶端膜面向中央管腔。对这些三维结构形态发生过程中标记蛋白分布的详细分析表明：（1）细胞-细胞接触足以触发顶端和基底外侧膜结构域的标记蛋白在膜的不同区域分离；（2）细胞-细胞接触诱导紧密连接蛋白ZO-1与细胞间接触区结合；（3）然而，紧密连接蛋白ZO-1定位于外侧膜顶端以及上皮轴的建立需要基膜的形成和细胞-基质接触；（4）在悬浮培养中，MDCK囊肿在中央管腔中分泌并形成基膜。这些结果表明，细胞-细胞和细胞-基质接触在极化上皮的形态发生中具有不同作用。我们认为，触发细胞极性的机制可能在体内不同的极化上皮中是共同的。
