title: Ultrastructural localization of caspase-14 in human epidermis.
abstract: Caspase-14 has been implicated in the formation of stratum corneum because of its specific expression and activation in terminally differentiating keratinocytes. However, its precise physiological role and its protein substrate are elusive. We studied the ultrastructural localization of caspase-14 in human epidermis to compare its distribution pattern with that of well-characterized differentiation markers. Immunogold cytochemistry confirmed that caspase-14 is nearly absent in basal and spinous layers. In the granular, layer nuclei and keratohyalin granules were labeled with increasing intensity towards the transitional layer. Particularly strong caspase-14 labeling was associated with areas known to be occupied by involucrin and loricrin, whereas F-granules, occupied by profilaggrin/filaggrin, were much less labeled. A high density of gold particles was also present at the forming cornified cell envelope, including desmosomes. In corneocytes, intense labeling was both cytoplasmic and associated with nuclear remnants and corneodesmosomes. These observations will allow focusing efforts of biochemical substrate screening on a subset of proteins localizing to distinct compartments of terminally differentiated keratinocytes.
authors.affiliation: Dipartimento di Biologia Evoluzionistica Sperimentale, University of Bologna, Bologna, Italy. Alibardi@biblio.cib.unibo.it
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Alibardi
authors.forename: Michael
authors.initials: M
authors.lastname: Dockal
authors.forename: Christina
authors.initials: C
authors.lastname: Reinisch
authors.forename: Erwin
authors.initials: E
authors.lastname: Tschachler
authors.forename: Leopold
authors.initials: L
authors.lastname: Eckhart
mesh_terms: D053456:Caspase 14; D020169:Caspases / Q000378:metabolism*; D004817:Epidermis / Q000201:enzymology* / Q000648:ultrastructure; D005260:Female; D000091344:Filaggrin Proteins; D006801:Humans; D016253:Microscopy, Immunoelectron
chemical_list: C000717249:FLG protein, human; D000091344:Filaggrin Proteins; C506446:CASP14 protein, human; D053456:Caspase 14; D020169:Caspases