Interaction between PAR-3 and the aPKC-PAR-6 complex is indispensable for apical domain development of epithelial cells
Interaction between PAR-3 and the aPKC-PAR-6 complex is indispensable for apical domain development of epithelial cells
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DOI：
10.1242/jcs.043174
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发表时间：
2009-05-15
影响因子：
4
通讯作者：
Ohno, Shigeo
中科院分区：
文献类型：
--
作者：
Horikoshi, Yosuke;Suzuki, Atsushi;Ohno, Shigeo
进化上保守的极性蛋白PAR-3、非典型蛋白激酶C(APKC)和PAR-6对上皮器官发育所需的顶膜发育起着关键的调节作用。然而，其作用的分子机制仍有待阐明。我们证明，在MDCK细胞中，PAR-3基因敲除阻碍了顶端蛋白向质膜的运输，并最终导致在二维和三维培养系统中在细胞间区错误定位的顶端区域的形成。野生型PAR-3可以有效地修复PAR-3基因敲除细胞中的缺陷，但缺乏与aPKC相互作用能力的点突变(S827/829A)却不能有效地修复这些缺陷，这表明PAR-3-aPKC-PAR-6复合体的形成是顶膜发育所必需的。这与紧密连接成熟形成鲜明对比，紧密连接成熟不一定依赖于aPKC-PAR-3相互作用，表明上皮极性所必需的两个基本过程受这些极性蛋白的不同调控。重要的是，高度去极化的细胞在含有顶端蛋白的液泡上积累aPKC和PAR-6，而不是PAR-3，在复极化过程的初始阶段，这些液泡成为PAR-3阳性的原始细胞-细胞接触部位的靶点。因此，PAR-3-aPKC-PAR-6复合体的形成可能不仅需要靶向aPKC-PAR-6复合体，而且还需要将顶端蛋白载体囊泡靶向原始连接结构。
The evolutionarily conserved polarity proteins PAR-3, atypical protein kinase C (aPKC) and PAR-6 critically regulate the apical membrane development required for epithelial organ development. However, the molecular mechanisms underlying their roles remain to be clarified. We demonstrate that PAR-3 knockdown in MDCK cells retards apical protein delivery to the plasma membrane, and eventually leads to mislocalized apical domain formation at intercellular regions in both two-dimensional and three-dimensional culture systems. The defects in PAR-3 knockdown cells are efficiently rescued by wild-type PAR-3, but not by a point mutant (S827/829A) that lacks the ability to interact with aPKC, indicating that formation of the PAR-3-aPKC-PAR-6 complex is essential for apical membrane development. This is in sharp contrast with tight junction maturation, which does not necessarily depend on the aPKC-PAR-3 interaction, and indicates that the two fundamental processes essential for epithelial polarity are differentially regulated by these polarity proteins. Importantly, highly depolarized cells accumulate aPKC and PAR-6, but not PAR-3, on apical protein-containing vacuoles, which become targeted to PAR-3-positive primordial cell-cell contact sites during the initial stage of the repolarization process. Therefore, formation of the PAR-3-aPKC-PAR-6 complex might be required for targeting of not only the aPKC-PAR-6 complex but also of apical protein carrier vesicles to primordial junction structures.