Corneodesmosin, a corneodesmosome-specific basic protein, is expressed in the cornified epithelia of the pig, guinea pig, rat, and mouse.
ABSTRACT Proteolysis of corneodesmosin, a 52- to 56-kDa basic protein located in the extracellular part of the modified desmosomes (corneodesmosomes) of human cornified epithelia, is thought to be a key event of desquamation. Three monoclonal antibodies specific for human corneodesmosin were used to search for the expression of the protein in other mammals. Cryosections of pig, guinea pig, rat, and mouse cornified tissues and proteins sequentially extracted from the corresponding epithelia were analyzed by immunofluorescence and immunoblotting, respectively. Two of the antibodies (F28-27 and B17-21) showed, on the epidermis of the four species and on the cornified epithelia of the rat tongue and esophagus, the same labeling as on human epidermis. Cytoplasmic in the lower granular layer, then pericellular microgranular, the labeling progressively disappeared in the lower cornified layer. By contrast, it persisted up to the surface in the rat tail epidermis. The two antibodies immunodetected basic proteins extracted with isotonic buffer from the epidermis of the pig (50 kDa), guinea pig (52 kDa), and mouse (75 kDa) and from the cornified epithelia of the rat (75 kDa). Immunoreactive proteins of lower Mr were also extracted partly with urea and partly with a reducing agent. The third antibody (G36-19) presented the same reactivities except on murine tissues, where it was unreactive. Our results show that the location, the biochemical characteristics, and the processing of corneodesmosin are similar in five mammals, including humans, suggesting an important role for this protein. They open the way to studies of its function in desquamation using various animal models.
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ABSTRACT: Although the acidic surface pH of the skin has been known for over a century, the stratum corneum (SC) pH gradient has been discovered only recently. After removal of SC layers with sequential tape strips, in humans, surface pH starts at 4.5–5.3, increasing by about 2–3 units until it reaches 6.8 in the lower SC. Both exogenous [free fatty acids (FFA) from sebaceous lipid, microbial metabolites, lactic acid from eccrine glands] and endogenous epidermal (enzymatic; membrane antiporters/pumps) mechanisms have been hypothesized to contribute to SC acidification. Three endogenous mechanisms have been identified to date that not only could influence SC pH, but also regulate one or more key SC functions: (1) the histidine-to-urocanic-acid pathway; (2) the phospholipid-to-FFA pathway, and (3) the sodium proton antiporter (NHE1). Additional factors that influence human surface pH have been detected. Endogenous factors, unrelated to pathological features, such as racial differences, topographical variation, gender differences, developmental and age-related changes have been reported. In contrast to adults, human newborn SC displays a near-neutral surface pH, which declines rapidly over the first postnatal month. Furthermore, endogenous factors have been described, as in atopic dermatitis, seborrheic dermatitis, diabetes, renal insufficiency and ichthyosis associated with an increased pH. Exogenous factors, like the use of detergents and cleansing products as well as SC hydration, can modify the surface pH. The consequences of SC acidification for several key SC functions are becoming clear, including (1) the role of an acidic pH for SC permeability barrier homeostasis, (2) the pH dependence of extracellular lipid processing and (3) SC integrity/cohesion. Integrity is defined as a measure of resistance to dissociation of adjacent corneocytes by tape stripping (cohesion is a related index defined as the amount of protein removed per stripping). (4) Proteolytic processes leading to desquamation are pH dependent, and (5) an acidic pH provides important antimicrobial resistance.Exogenous Dermatology 01/2002; 1(4):163-175.
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ABSTRACT: To understand the biochemical abnormalities that underlie the reduced desquamation observed in dry skin, we analyzed corneodesmosome degradation in normal and winter xerosis skin. Western blotting of total proteins from corneocytes obtained by varnish-strippings from the legs of 56 volunteers with normal (26) or xerotic (30) skin was performed using antibodies specific for (corneo)desmosome proteins. In the whole population, the amounts of desmoglein 1 and plakoglobin were found to be correlated, but were not related to the amounts of corneodesmosin. This suggests simultaneous proteolysis for the former proteins differing from that of corneodesmosin. Neither entire desmoplakins nor any proteolysis-derived fragments were detected. The amounts of corneodesmosin, desmoglein 1, and plakoglobin detected were found to be significantly higher in xerotic compared with normal skin extracts. Conventional and freeze-fracture electron microscopy showed the absence of nonperipheral corneodesmosomes in the upper stratum corneum of normal skin but the presence of a significant number of these structures in the same layer of winter xerosis skin. These results provide a more precise description of the proteolysis of corneodesmosome components in the upper cornified layer of the epidermis. They support previous studies demonstrating the importance of corneodesmosome degradation in desquamation and reveal that the nonperipheral corneodesmosomes, which are totally degraded during maturation of the stratum corneum in normal skin, persist in winter xerosis, probably leading to abnormal desquamation.Keywords: desmosomes, epidermis, keratinocytes, proteasesJournal of Investigative Dermatology 12/2000; 116(1):23-30. · 6.37 Impact Factor
- American Journal of Infection Control 12/2006; 34(10). · 2.33 Impact Factor