Subcellular distribution of tight junction-associated proteins (occludin, ZO-1, ZO-2) in rodent skin

J Invest Dermatol. 1998 Jun;110(6):862-6. doi: 10.1046/j.1523-1747.1998.00209.x.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Cells, Cultured
  • Epithelial Cells / chemistry
  • Female
  • Freeze Fracturing
  • Frozen Sections
  • Immunoblotting
  • Immunohistochemistry
  • Male
  • Membrane Proteins / analysis
  • Mice
  • Microscopy, Fluorescence
  • Microscopy, Immunoelectron
  • Occludin
  • Phosphoproteins / analysis
  • Skin / chemistry*
  • Skin / cytology
  • Skin / ultrastructure
  • Subcellular Fractions / chemistry
  • Tight Junctions / chemistry*
  • Tight Junctions / ultrastructure
  • Zonula Occludens-1 Protein
  • Zonula Occludens-2 Protein

Substances

  • Membrane Proteins
  • Occludin
  • Ocln protein, mouse
  • Phosphoproteins
  • Tjp1 protein, mouse
  • Tjp2 protein, mouse
  • Zonula Occludens-1 Protein
  • Zonula Occludens-2 Protein