Subcellular distribution of tight junction-associated proteins (occludin, ZO-1, ZO-2) in rodent skin.
Occludin is an integral membrane protein that is concentrated at tight junctions (zonulae occludentes) in simple epithelial cells. ZO-1 and ZO-2 are peripheral membrane proteins that are localized at tight junctions in simple epithelial cells and at cadherin-based adherens junctions in nonepithelial cells. In this study, we investigated the expression and subcellular distribution of occludin, ZO-1, and ZO-2 in rodent skin. Immunoblotting detected all of these molecules in isolated epidermis, but the occludin/ZO-1 (or occludin/ZO-2) ratio was significantly lower than that in cultured simple epithelial cells. In the epidermis of adult skin, occludin was concentrated at cell-cell borders only in the most superficial zone of the granular cell layer, whereas ZO-1 and ZO-2 were distributed in a much broader zone from the spinous to the granular layers. During mouse skin development, this peculiar distribution of occludin in the epidermis appeared when the periderm, a simple epithelium bearing typical occludin-based tight junctions, was sloughed off at embryonic day 16.5 of gestation. Freeze-fracture electron microscopy identified the so-called focal strands or maculae occludentes, i.e., spot tight junction-like structures, between adjacent granular cells, and anti-occludin monoclonal antibody exclusively labeled these focal strands. In hair follicles, occludin and ZO-1 were colocalized at cell-cell borders in Henle's layer and the cornifying cuticle of the inner root sheath. In addition, ZO-1 but not occludin were localized weakly at the outer root sheath and intensely at the hair cortex/matrix.
Morita
K
K
Department of Cell Biology, Faculty of Medicine, Kyoto University, Japan.
Itoh
M
M
Saitou
M
M
Ando-Akatsuka
Y
Y
Furuse
M
M
Yoneda
K
K
Imamura
S
S
Fujimoto
K
K
Tsukita
S
S
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000737:chemistry; D005260:Female; D005614:Freeze Fracturing; D005629:Frozen Sections; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D062793:Occludin; D010750:Phosphoproteins / Q000032:analysis; D012867:Skin / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000737:chemistry; D019108:Tight Junctions / Q000737:chemistry* / Q000648:ultrastructure; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; C569047:Tjp2 protein, mouse; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein