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- Title
PAR-6 regulates aPKC activity in a novel way and mediates cell-cell contact-induced formation of the epithelial junctional complex.
- Authors
Yamanaka, Tomoyuki; Horikoshi, Yosuke; Suzuki, Atsushi; Sugiyama, Yuki; Kitamura, Koichi; Maniwa, Rika; Nagai, Yoko; Yamashita, Akio; Hirose, Tomonori; Ishikawa, Hiroko; Ohno, Shigeo
- Abstract
Background PAR-6, aPKC and PAR-3 are polarity proteins that co-operate in the establishment of cell polarity in Caenorhabditis elegans and Drosophila embryos. We have recently shown that mammalian aPKC is required for the formation of the epithelia-specific cell-cell junctional structure. We have also revealed that a mammalian PAR-6 forms a ternary complex with aPKC and ASIP/PAR-3, and localizes at the most apical end of the junctional complex in epithelial cells. Results The ternary complex formation and junctional co-localization of PAR-6 with aPKC and ASIP/PAR-3 are observed during the early stage of epithelial cell polarization. In addition, over-expression of the PAR-6 mutant with CRIB/PDZ domain in MDCK cells disturbs the cell-cell contact-induced junctional localization of tight junction proteins, as well as inhibiting TER development. Furthermore, 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 aPKC has the intrinsic potential to activate aPKC, which is only released when Cdc42:GTP binds to the CRIB/PDZ domain. Conclusion The results indicate the involvement of PAR-6 in the aPKC function which is required for the cell-cell adhesion-induced formation of epithelial junctional structures, possibly through the cooperative regulation of aPKC activity with Cdc42.
- Subjects
EPITHELIAL cells; IMMUNOFLUORESCENCE
- Publication
Genes to Cells, 2001, Vol 6, Issue 8, p721
- ISSN
1356-9597
- Publication type
Article
- DOI
10.1046/j.1365-2443.2001.00453.x