Epithelial barrier function: assembly and structural features of the cornified cell envelope.
Terminally differentiating stratified squamous epithelial cells assemble a specialized protective barrier structure on their periphery termed the cornified cell envelope (CE). It is composed of numerous structural proteins that become cross-linked by several transglutaminase enzymes into an insoluble macromolecular assembly. Several proteins are involved in the initial stages of CE assembly, but only certain proteins from a choice of more than 20 different proteins are used in the final stages of CE reinforcement, apparently to meet tissue-specific requirements. In addition, a variable selection of proteins may be upregulated in response to genetic defects of one of the CE proteins or tissue injury, in an effort to maintain an effective barrier. Additionally, in the epidermis and hair fiber cuticle, a layer of lipids is covalently attached to the proteins, which provides essential water barrier properties. Here we describe our current understanding of CE structure, a possible mechanism of its assembly, and various disorders that cause a defective barrier.
Kalinin
Andrey E
AE
Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Kajava
Andrey V
AV
Steinert
Peter M
PM
D000818:Animals; D003598:Cytoskeletal Proteins / Q000737:chemistry; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D051179:Plakins; D011392:Proline / Q000737:chemistry; D011498:Protein Precursors / Q000737:chemistry; D011503:Transglutaminases / Q000737:chemistry
D003598:Cytoskeletal Proteins; D008055:Lipids; D008565:Membrane Proteins; C491674:PPL protein, human; D051179:Plakins; D011498:Protein Precursors; C100754:envoplakin; C032253:involucrin; D011392:Proline; D011503:Transglutaminases