Atypical protein kinase C is involved in the evolutionarily conserved par protein complex and plays a critical role in establishing epithelia-specific junctional structures.
We have previously shown that during early Caenorhabditis elegans embryogenesis PKC-3, a C. elegans atypical PKC (aPKC), plays critical roles in the establishment of cell polarity required for subsequent asymmetric cleavage by interacting with PAR-3 [Tabuse, Y., Y. Izumi, F. Piano, K.J. Kemphues, J. Miwa, and S. Ohno. 1998. Development (Camb.). 125:3607--3614]. Together with the fact that aPKC and a mammalian PAR-3 homologue, aPKC-specific interacting protein (ASIP), colocalize at the tight junctions of polarized epithelial cells (Izumi, Y., H. Hirose, Y. Tamai, S.-I. Hirai, Y. Nagashima, T. Fujimoto, Y. Tabuse, K.J. Kemphues, and S. Ohno. 1998. J. Cell Biol. 143:95--106), this suggests a ubiquitous role for aPKC in establishing cell polarity in multicellular organisms. Here, we show that the overexpression of a dominant-negative mutant of aPKC (aPKCkn) in MDCK II cells causes mislocalization of ASIP/PAR-3. Immunocytochemical analyses, as well as measurements of paracellular diffusion of ions or nonionic solutes, demonstrate that the biogenesis of the tight junction structure itself is severely affected in aPKCkn-expressing cells. Furthermore, these cells show increased interdomain diffusion of fluorescent lipid and disruption of the polarized distribution of Na(+),K(+)-ATPase, suggesting that epithelial cell surface polarity is severely impaired in these cells. On the other hand, we also found that aPKC associates not only with ASIP/PAR-3, but also with a mammalian homologue of C. elegans PAR-6 (mPAR-6), and thereby mediates the formation of an aPKC-ASIP/PAR-3-PAR-6 ternary complex that localizes to the apical junctional region of MDCK cells. These results indicate that aPKC is involved in the evolutionarily conserved PAR protein complex, and plays critical roles in the development of the junctional structures and apico-basal polarization of mammalian epithelial cells.
Department of Molecular Biology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan.
A
A
Suzuki
T
T
Yamanaka
T
T
Hirose
N
N
Manabe
K
K
Mizuno
M
M
Shimizu
K
K
Akimoto
Y
Y
Izumi
T
T
Ohnishi
S
S
Ohno
D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D018797:Cell Cycle Proteins; D002460:Cell Line; D016764:Cell Polarity; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D005456:Fluorescent Dyes / Q000378:metabolism; D018014:Gene Transfer Techniques; D015801:Helminth Proteins / Q000378:metabolism*; D046911:Macromolecular Substances; D008563:Membrane Lipids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D015820:Cadherins; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D018797:Cell Cycle Proteins; D005456:Fluorescent Dyes; D015801:Helminth Proteins; D046911:Macromolecular Substances; D008563:Membrane Lipids; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; C115084:Pard3 protein, mouse; D010750:Phosphoproteins; D011506:Proteins; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; C512642:par-6 protein, C elegans; C097238:PAR-3 protein, C elegans; D017346:Protein Serine-Threonine Kinases; C115015:PKC-3 protein; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium