title: Acid and neutral sphingomyelinase, ceramide synthase, and acid ceramidase activities in cutaneous aging.
abstract: In aged skin, decreased levels of stratum corneum ceramides have been described. Epidermal ceramides are generated by sphingomyelin hydrolysis or synthesis from sphingosin and fatty acids and are degraded by ceramidase. We recently showed that epidermal acid sphingomyelinase (A-SMase) generates ceramides with structural function in the stratum corneum lipid bilayers, which provide for the permeability barrier function of the skin. Here, we examined the activities of epidermal A-SMase, ceramide synthase, and ceramidase in chronologically aged versus young hairless mouse skin. We found reduced A-SMase and ceramide synthase activities in the epidermis of aged mice. However, studies on enzyme localization revealed unchanged, ongoing high A-SMase activity in the outer epidermis, which correlated with reported normal barrier function found in aged skin under basal conditions. Reduced A-SMase and ceramide synthase activity was noted in the inner epidermis, correlating with reduced capacity for permeability barrier repair in aging. Ceramidase activity was not age dependent. In summary, we found reduced activities of ceramide-generating SMase and ceramide synthase in the inner epidermis of aged skin, explaining its reduced capacity in barrier repair. In contrast, A-SMase activity in the outer epidermis was unchanged, indicating that this enzyme is crucially involved in basal permeability barrier homeostasis.
authors: Department of Dermatology, University of Kiel, Germany.
authors: Jens-Michael
authors: JM
authors: Jensen
authors: Michael
authors: M
authors: Förl
authors: Supandi
authors: S
authors: Winoto-Morbach
authors: Sophie
authors: S
authors: Seite
authors: Michael
authors: M
authors: Schunck
authors: Ehrhardt
authors: E
authors: Proksch
authors: Stefan
authors: S
authors: Schütze
mesh_terms: D000375:Aging; D000818:Animals; D004817:Epidermis / Q000378:metabolism; D005083:Exfoliatins / Q000378:metabolism; D002517:Galactosylgalactosylglucosylceramidase / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry; D051379:Mice; D008812:Mice, Hairless; D010088:Oxidoreductases / Q000378:metabolism*; D010539:Permeability; D012867:Skin / Q000378:metabolism / Q000473:pathology; D015595:Skin Aging; D012879:Skin Physiological Phenomena; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D013109:Sphingomyelins
chemical_list: D005083:Exfoliatins; D008051:Lipid Bilayers; D013109:Sphingomyelins; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D013108:Sphingomyelin Phosphodiesterase; D002517:Galactosylgalactosylglucosylceramidase