Acylceramides and lanosterol-lipid markers of terminal differentiation in cultured human keratinocytes: Modulating effect of retinoic acid |
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Authors: | J Brod E Bavelier P Justine A Weerheim M Ponec |
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Institution: | (1) Department of Biology, L’Oréal Research Laboratories, 1 Av. E. Schueller, F-93600 Aulnay ss Bois, France;(2) Department of Dermatology, University Hospital Leiden, The Netherlands |
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Abstract: | Epidermal differentiation is accompanied by profound changes in the synthesis of a variety of intracellular proteins and intercellular
lipids. In conventional, submerged culture keratinocytes have been shown to lose the ability to synthesize the protein markers
of differentiation. They re-express them, however, when they are cultured in medium supplemented with delipidized retinoic
acid (RA)-depleted] serum or in air-exposed cultures using de-epidermized dermis (DED) as a substrate. Recent studies have
revealed that acylceramides (AC) and lanosterol (LAN), which are present only in trace amounts in cultures of keratinocytes
grown under submerged conditions on DED in medium supplemented with normal serum, become expressed in significant amounts
when the culture is lifted to the air-liquid interface. Inasmuch as culture conditions may markedly affect the extent of keratinocyte
differentiation, the present study aimed to investigate the effect of normal (RA-containing) or delipidized (RA-depleted)
serum and of RA administration on lipid composition (especially of the AC and LAN contents) in cells cultured under submerged
and air-exposed conditions. To test a possible effect of dermal substrate (used in the air-exposed model), the lipid composition
of keratinocytes grown under submerged conditions on a plastic and on a dermal substrate (de-epidermized dermis, DED) has
also been compared. The results revealed that under all culture conditions, RA deprivation of fetal bovine serum resulted
in a marked increase of total ceramide content. Even under submerged conditions, the presence of both AC and LAN could be
detected. In air-exposed culture, the content of these lipids was markedly increased. Addition of RA at 1 μM concentration to cultures grown in RA-depleted medium induced marked changes in lipid composition under all culture conditions
tested. In cells grown under submerged conditions (both on plastic and on DED) AC and LAN were no longer present in detectable
amounts. Also in air-exposed culture, a marked decrease in the content of these lipids was observed. These results suggest
that liposoluble serum components, like RA, control the synthesis of lipids that are present in later stages of epidermal
differentiation. |
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Keywords: | reconstructed epidermis keratinocyte differentiation lipids retinoic acid |
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