β-Glucocerebrosidase activity in mammalian stratum corneum

Abstract

Although previous studies have demonstrated a crucial role for the enzyme ␤ -glucocerebrosidase (GlcCer'ase) in the final steps of membrane structural maturation in mammalian stratum cornuem (SC) and epidermal homeostasis, the precise in vivo localization of GlcCer'ase activity and protein is not known. Here, we developed a fluorogenic in situ assay on histologic sections (zymography) to elucidate the in vivo distribution of GlcCer'ase activity, and further characterized and localized the SC GlcCer'ase activity in vitro. The zymographic technique revealed higher GlcCer'ase activity in upper stratum granulosum and SC, both in murine and human SC; activity that was both inhibited by conduritol B epoxide, a specific GlcCer'ase inhibitor, and pH-dependent; i.e., present at pH 5.2, and absent or significantly reduced at neutral pH (7.4), consistent with the known pH optimum for epidermal GlcCer'ase in vitro. Immunohistochemical staining for GlcCer'ase protein showed enhanced fluorescent signal in the outer layers of human epidermis, concentrated at the apex and margins of stratum granulosum and lower SC. Moreover, in extracts from individual epidermal layers, GlcCer'ase activity was present throughout murine epidermis, with the highest activity in the SC, peaking in the lower-to-mid-SC. The SC activity was stimulated Ͼ 10-fold by sodium taurocholate, and inhibited by bromoconduritol B epoxide. Finally, isolated membrane couplets, prepared from SC sheets, also demonstrated significant GlcCer'ase activity. These data localize GlcCer'ase activity to the outer epidermis by three different techniques, and support the role of this enzyme in extracellular processing of glucosylceramides to ceramides, required for permeability barrier maturation and function. -Takagi, Y.

Cutting Edge of the Pathogenesis of Atopic Dermatitis: Sphingomyelin Deacylase, the Enzyme Involved in Its Ceramide Deficiency, Plays a Pivotal Role

“…In contrast, the SC from patients with contact dermatitis showed no increase in SM deacylase activity compared with HCs, which suggests that changes in SM deacylase activity are unlikely to be involved in the general etiology of cutaneous inflammation. Our earlier study on the epidermal localization of aCDase and BGCase, the latter being a hydrolytic enzyme localized in intercellular spaces between the SC and the granular layer, suggested that the activities of ceramide metabolism-related enzymes within the SC approximately represent the epidermal activities of the same enzymes [56][57][58]. Consistent with that relationship, a similar higher level of SM deacylase activity was detected in the epidermis from AD skin (Figure 15), whereas there was no significant difference in levels of aSMase between AD skin and HC skin [50], which suggests that epidermal cells from AD patients show abnormal production of the hitherto undiscovered epidermal enzyme termed SM deacylase.…”

Inherited disorders of complex lipid metabolism: A clinical review

“…Glucosylceramides can be further modified in the extracellular space associated with the lysosomal storage disorder, glucocerebrosidase is also located in the stratum corneum where its role in converting glucosylceramides into ceramides is required for lipid barrier maturation. 47 ULCFAs are also enriched in both brain and retina tissue. 48 In animal models, ULCFAs are found in phosphatidylcholine (PC) (discussed in the next section) in both these tissues.…”

The cutaneous lipid composition of bat wing and tail membranes: a case of convergent evolution with birds

“…Cerebrosides are absent in the mammalian SC because of the activity of the enzyme b-glucocerebrosidase, which cleaves the sugar moieties from cerebrosides to make ceramides in the basal layers of the epidermis [10]. Individuals deficient in b-glucocerebrosidase accumulate cerebrosides in the SC, a condition that results in Gaucher's disease, which substantially increases CEWL [3,10].…”

“…Cerebrosides are absent in the mammalian SC because of the activity of the enzyme b-glucocerebrosidase, which cleaves the sugar moieties from cerebrosides to make ceramides in the basal layers of the epidermis [10]. Individuals deficient in b-glucocerebrosidase accumulate cerebrosides in the SC, a condition that results in Gaucher's disease, which substantially increases CEWL [3,10]. The hexose moiety of cerebrosides can bind to molecules of water, which is thought to disrupt the lamellar packing; both characteristics that apparently increase rates of water loss [3,10].…”