title: Formation of the epidermal calcium gradient coincides with key milestones of barrier ontogenesis in the rodent.
abstract: The epidermal permeability barrier forms late in gestation, coincident with decreased lipid synthesis, increased lipid processing, and development of a mature, multi-layered stratum corneum. Prior studies have shown that changes in the epidermal Ca++ gradient in vivo regulate lamellar body secretion and lipid synthesis, and modulations in extracellular Ca++ in vitro also regulate keratinocyte differentiation. We asked here whether a Ca++ gradient forms in fetal epidermis in utero, and whether its emergence correlates with key developmental milestones of barrier formation and stratum corneum development. Using either ion precipitation or proton induced X-ray emission analysis of fetal mouse and rat skin, we showed that a Ca++ gradient is not present at gestational days 16-18, prior to barrier formation, and that a gradient forms coincident with the emergence of barrier competence (day 19, mouse; day 20, rat) prior to birth. These results are consistent with a role for Ca++ in the regulation of key metabolic events leading to barrier formation. Whether the calcium gradient is formed actively or passively remains to be determined.
authors.affiliation: Dermatology and Medicine (Metabolism) Services, Veterans Administration Medical Center, Department of Dermatology, University of California School of Medicine, San Francisco 94121, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Elias
authors.forename: P
authors.initials: P
authors.lastname: Nau
authors.forename: K
authors.initials: K
authors.lastname: Hanley
authors.forename: C
authors.initials: C
authors.lastname: Cullander
authors.forename: D
authors.initials: D
authors.lastname: Crumrine
authors.forename: G
authors.initials: G
authors.lastname: Bench
authors.forename: E
authors.initials: E
authors.lastname: Sideras-Haddad
authors.forename: T
authors.initials: T
authors.lastname: Mauro
authors.forename: M L
authors.initials: ML
authors.lastname: Williams
authors.forename: K R
authors.initials: KR
authors.lastname: Feingold
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005314:Embryonic and Fetal Development / Q000502:physiology; D004817:Epidermis / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D005333:Fetus / Q000378:metabolism* / Q000502:physiology; D006651:Histocytochemistry; D008297:Male; D051379:Mice / Q000196:embryology; D008854:Microscopy, Electron; D010539:Permeability; D051381:Rats / Q000196:embryology; D017207:Rats, Sprague-Dawley; D013052:Spectrometry, X-Ray Emission
chemical_list: D002118:Calcium