PMID- 10231017
OWN - NLM
STAT- MEDLINE
DCOM- 19990823
LR  - 20051116
IS  - 1226-3613 (Print)
IS  - 1226-3613 (Linking)
VI  - 31
IP  - 1
DP  - 1999 Mar 31
TI  - Bricks and mortar of the epidermal barrier.
PG  - 5-19
AB  - A specialized tissue type, the keratinizing epithelium, protects terrestrial
      mammals from water loss and noxious physical, chemical and mechanical insults.
      This barrier between the body and the environment is constantly maintained by
      reproduction of inner living epidermal keratinocytes which undergo a process of
      terminal differentiation and then migrate to the surface as interlocking layers
      of dead stratum corneum cells. These cells provide the bulwark of mechanical and 
      chemical protection, and together with their intercellular lipid surroundings,
      confer water-impermeability. Much of this barrier function is provided by the
      cornified cell envelope (CE), an extremely tough protein/lipid polymer structure 
      formed just below the cytoplasmic membrane and subsequently resides on the
      exterior of the dead cornified cells. It consists of two parts: a protein
      envelope and a lipid envelope. The protein envelope is thought to contribute to
      the biomechanical properties of the CE as a result of cross-linking of
      specialized CE structural proteins by both disulfide bonds and
      N(epsilon)-(gamma-glutamyl)lysine isopeptide bonds formed by transglutaminases.
      Some of the structural proteins involved include involucrin, loricrin, small
      proline rich proteins, keratin intermediate filaments, elafin, cystatin A, and
      desmosomal proteins. The lipid envelope is located on the exterior of and
      covalently attached by ester bonds to the protein envelope and consists of a
      monomolecular layer of omega-hydroxyceramides. These not only serve of provide a 
      Teflon-like coating to the cell, but also interdigitate with the intercellular
      lipid lamellae perhaps in a Velcro-like fashion. In fact the CE is a common
      feature of all stratified squamous epithelia, although its precise composition,
      structure and barrier function requirements vary widely between epithelia. Recent
      work has shown that a number of diseases which display defective epidermal
      barrier function, generically known as ichthyoses, are the result of genetic
      defects of the synthesis of either CE proteins, the transglutaminase 1
      cross-linking enzyme, or defective metabolism of skin lipids.
FAU - Nemes, Z
AU  - Nemes Z
AD  - Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal
      and Skin Diseases, National Institutes of Health, Maryland 20892-2752, USA.
FAU - Steinert, P M
AU  - Steinert PM
LA  - eng
PT  - Journal Article
PT  - Review
PL  - United States
TA  - Exp Mol Med
JT  - Experimental & molecular medicine
JID - 9607880
RN  - 0 (Membrane Lipids)
RN  - 0 (Membrane Proteins)
RN  - EC 2.3.2.13 (Transglutaminases)
SB  - IM
MH  - Animals
MH  - Cell Membrane/metabolism
MH  - Epidermis/*chemistry/*metabolism
MH  - Humans
MH  - Ichthyosis/genetics/metabolism
MH  - Keratinocytes/chemistry/*metabolism
MH  - Membrane Lipids/*metabolism
MH  - Membrane Proteins/*metabolism
MH  - Transglutaminases/metabolism
RF  - 220
EDAT- 1999/05/07 00:00
MHDA- 1999/05/07 00:01
CRDT- 1999/05/07 00:00
PHST- 1999/05/07 00:00 [pubmed]
PHST- 1999/05/07 00:01 [medline]
PHST- 1999/05/07 00:00 [entrez]
AID - 10.1038/emm.1999.2 [doi]
PST - ppublish
SO  - Exp Mol Med. 1999 Mar 31;31(1):5-19. doi: 10.1038/emm.1999.2.