Analyses of the universal molecular machinary involved in cell polarization

参与细胞极化的通用分子机制的分析

基本信息

批准号：
11480182
负责人：
OHNO Shigeo
金额：
$ 9.86万
依托单位：
Yokohama City University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11480182/
关键词：
aPKC ASIP PAR-3 PAR-6 C.elegans asymmetric cell division polarity epithelia

项目摘要

We as well as other people working on C.elegans and Drosophia revealed that aPKC, PAR-3 and PAR-6 are polarity proteins that co-operate in the establishment of cell polarity in C.elegans and Drosophila embryos. These three proteins co-localize asymjmetrically in C.elegans one-cell ambryo and in Drosophial epithelial cells and neuroblasts. Here we have shown that, in mammalian elitheial cells, these three proteins co-localize to the apical end of the junctional complex, tight junctions. Furthermore, we have shown that aPKC is required for the formation of the epithelia-specific cell-cell junctional structure, and thus plays an indispensable role in the establishment of mammalian epithelial cell polarity. The formation of a ternary complex with aPKC, as well as co-localization at the most apical end of the junctional complex, also suggest the involvement of a mammalian homologue of PAR-6 and PAR-3, ASIP, in this aPKC function in epithelial cell polarization. We also show that the pre-existing ternary complex translocates to the cell-cell contact region in response to cell adhesion. Furthermore, overexpression of PAR-6 mutant lacking the aPKC-binding region in MDCK cells disturbs the cell-cell contact-induced junctional localization of tight junction proteins, as well as inhibiting TER development. These results not only indicate the involvement of the ternary complex in aPKC function. Consistent with this, the binding of Cdc42 : GTP to the CRIB/PDZ domain of PAR-6 enhances the kinase activity of PAR-6-bound aPKC.Detailed analyses suggest that the binding of PAR-6 to the N-terminal region of aPKC has the intrinsic potential to activate aPKC, which is released only when Cdc42 : GTP binds to the CRIB/PDZ domain. Taken together, the results suggest not only a novel mode of aPKC activation, but also the possible involvement of this regulation in the early phase of epithelial cell polarization.

我们以及其他从事C.Elegans和rotosophia的人都表明，APKC，PAR-3和PAR-6都是极性蛋白，它们在C.Elegans和果蝇胚胎中建立细胞极性方面合作。这三种蛋白质在C.Elegans One-cell Ambryo以及果蝇上皮细胞和神经细胞中均一地共定位。在这里，我们已经表明，在哺乳动物的元素细胞中，这三种蛋白会共定位到连接络合物，紧密连接的顶端。此外，我们已经表明，APKC是上皮特异性细胞连接结构所必需的，因此在哺乳动物上皮细胞极性的建立中起着不可或缺的作用。三元复合物与APKC的形成以及在连接络合物的最根尖端的共定位也表明，该APKC在上皮细胞极化中的作用。我们还表明，预先存在的三元复合物响应细胞粘附而转移到细胞 - 细胞接触区域。此外，MDCK细胞中缺乏APKC结合区域的Par-6突变体的过表达干扰了细胞 - 细胞接触诱导的紧密连接蛋白的连接点定位，并抑制了TER发育。这些结果不仅表明了三元复合物在APKC函数中的参与。 Consistent with this, the binding of Cdc42 : GTP to the CRIB/PDZ domain of PAR-6 enhances the kinase activity of PAR-6-bound aPKC.Detailed analyses suggest that the binding of PAR-6 to the N-terminal region of aPKC has the intrinsic potential to activate aPKC, which is released only when Cdc42 : GTP binds to the CRIB/PDZ domain.综上所述，结果不仅表明了一种新型的APKC激活模式，而且还表明了该调节在上皮细胞极化的早期阶段的可能参与。