title: Interaction between PAR-3 and the aPKC-PAR-6 complex is indispensable for apical domain development of epithelial cells.
abstract: 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.
authors.affiliation: Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Horikoshi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Sasaki
authors.forename: Keiko
authors.initials: K
authors.lastname: Mizuno
authors.forename: Hajime
authors.initials: H
authors.lastname: Sawada
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Yonemura
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ohno
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002450:Cell Communication; D018797:Cell Cycle Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D016764:Cell Polarity; D003094:Collagen / Q000378:metabolism; D003560:Cysts / Q000201:enzymology; D004285:Dogs; D004847:Epithelial Cells / Q000201:enzymology*; D005782:Gels; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D019108:Tight Junctions / Q000201:enzymology; D013997:Time Factors; D014162:Transfection; D014617:Vacuoles / Q000201:enzymology*; D028961:beta Karyopherins / Q000378:metabolism; D000099293:Protein Kinase C-lambda
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015815:Cell Adhesion Molecules; D018797:Cell Cycle Proteins; D003094:Collagen; D005782:Gels; D007527:Isoenzymes; D011493:Protein Kinase C; D034741:RNA, Small Interfering; D028961:beta Karyopherins; D000099293:Protein Kinase C-lambda; C499657:PARD6A protein, human; C115084:Pard3 protein, mouse; C424163:late gestation lung 2 karyopherin