ZO-1 and ZO-2 independently determine where claudins are polymerized in tight-junction strand formation.
A fundamental question in cell and developmental biology is how epithelial cells construct the diffusion barrier allowing them to separate different body compartments. Formation of tight junction (TJ) strands, which are crucial for this barrier, involves the polymerization of claudins, TJ adhesion molecules, in temporal and spatial manners. ZO-1 and ZO-2 are major PDZ-domain-containing TJ proteins and bind directly to claudins, yet their functional roles are poorly understood. We established cultured epithelial cells (1(ko)/2(kd)) in which the expression of ZO-1/ZO-2 was suppressed by homologous recombination and RNA interference, respectively. These cells were well polarized, except for a complete lack of TJs. When exogenously expressed in 1(ko)/2(kd) cells, ZO-1 and ZO-2 were recruited to junctional areas where claudins were polymerized, but truncated ZO-1 (NZO-1) containing only domains PDZ1-3 was not. When NZO-1 was forcibly recruited to lateral membranes and dimerized, claudins were dramatically polymerized. These findings indicate that ZO-1 and ZO-2 can independently determine whether and where claudins are polymerized.
Umeda
Kazuaki
K
Department of Cell Biology, Kyoto University Faculty of Medicine, Yoshida-Konoe, Kyoto 606-8501, Japan.
Ikenouchi
Junichi
J
Katahira-Tayama
Sayaka
S
Furuse
Kyoko
K
Sasaki
Hiroyuki
H
Nakayama
Mayumi
M
Matsui
Takeshi
T
Tsukita
Sachiko
S
Furuse
Mikio
M
Tsukita
Shoichiro
S
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D016764:Cell Polarity; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D019108:Tight Junctions / Q000378:metabolism* / Q000648:ultrastructure; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
D008565:Membrane Proteins; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; C569047:Tjp2 protein, mouse; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein