Barriers and more: functions of tight junction proteins in the skin.
Although the existence of tight junction (TJ) structures (or a secondary epidermal barrier) was postulated for a long time, the first description of TJ proteins in the epidermis (occludin, ZO-1, and ZO-2) was only fairly recent. Since then, a wealth of new insights concerning TJs and TJ proteins, including their functional role in the skin, have been gathered. Of special interest is that the epidermis as a multilayered epithelium exhibits a very complex localization pattern of TJ proteins, which results in different compositions of TJ protein complexes in different layers. In this review, we summarize our current knowledge about the role of TJ proteins in the epidermis in barrier function, cell polarity, vesicle trafficking, differentiation, and proliferation. We hypothesize that TJ proteins fulfill TJ structure-dependent and structure-independent functions and that the specific function of a TJ protein may depend on the epidermal layer where it is expressed.
Department of Dermatology and Venerology, University Hospital Hamburg-Eppendorf, Germany.
Nina
N
Kirschner
Johanna M
JM
Brandner
D000818:Animals; D057167:Claudins / Q000502:physiology; D004817:Epidermis / Q000502:physiology*; D004848:Epithelium / Q000502:physiology; D006801:Humans; D062793:Occludin / Q000502:physiology; D021381:Protein Transport; D062725:Tight Junction Proteins / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology*; D062826:Zonula Occludens-1 Protein / Q000502:physiology; D062827:Zonula Occludens-2 Protein / Q000502:physiology
D057167:Claudins; D062793:Occludin; C569042:TJP1 protein, human; D062725:Tight Junction Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein