Expression and distribution of ZO-3, a tight junction MAGUK protein, in mouse tissues.
BACKGROUND
Three related MAGUK proteins, ZO-1, ZO-2 and ZO-3, are concentrated at the cytoplasmic surface of tight junctions. However, in contrast to ZO-1/ZO-2, our knowledge of the expression and distribution of ZO-3 is still fragmentary, partly due to a lack of antibodies that specifically distinguish ZO-3 from ZO-1 and ZO-2.


RESULTS
We generated one pAb and one mAb that specifically recognized ZO-3 on Western blotting. The immunofluorescence signals obtained with these antibodies completely disappeared from ZO-1/ZO-2-positive tight junctions in the liver of ZO-3-deficient mice, indicating that the antibodies can be used to localize ZO-3 in various tissues by immunofluorescence microscopy. Immunofluorescence microscopy with these antibodies revealed that ZO-3 was concentrated at tight junctions in various types of epithelium, but not in endothelium or at cadherin-based cell-cell adhesion sites (spot adherens junctions of fibroblasts and intercalated discs of cardiac muscle cells), where ZO-1 and ZO-2 are concentrated.


CONCLUSIONS
We conclude that ZO-3 is expressed in a more epithelium-specific manner than ZO-1 and ZO-2. These observations provide for a better understanding of the functions of tight junction-associated MAGUKs.
Inoko
Akihito
A
Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Itoh
Masahiko
M
Tamura
Atsushi
A
Matsuda
Miho
M
Furuse
Mikio
M
Tsukita
Shoichiro
S
D000818:Animals; D000911:Antibodies, Monoclonal; D015152:Blotting, Northern; D015153:Blotting, Western; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D051528:Guanylate Kinases; D008099:Liver / Q000378:metabolism*; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D009703:Nucleoside-Phosphate Kinase / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D019108:Tight Junctions / Q000378:metabolism*; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; C569044:Tjp1 protein, rat; C569047:Tjp2 protein, mouse; C491774:Tjp3 protein, mouse; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; D005982:Glutathione Transferase; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases