title: Hyaluronan suppresses epidermal differentiation in organotypic cultures of rat keratinocytes.
abstract: Hyaluronan (hyaluronic acid, HA) is an abundant matrix component between keratinocytes of the epidermis in vivo, but its function there remains unclear. We used a lift culture model, in which rat epidermal keratinocytes (REKs) stratify at an air-liquid interface, to ask whether HA may regulate epidermal proliferation and/or differentiation. In this model, early markers of differentiation (keratin 10), and later markers (profilaggrin, keratohyalin granules, cornified layers) are faithfully expressed, both temporally and spatially. HA, measured using two different analytical techniques, accumulated to high levels only in the presence of an intact basement membrane that seals the epidermal compartment. To test whether HA has a functional role in differentiation, Streptomyces hyaluronidase (StrepH, 1 U/ml; digests >95% of HA within 4 h) was added daily to lift cultures during stratification time-course experiments over 5 days. In StrepH-treated cultures, the expression of profilaggrin and the number and size of keratohyalin granules were significantly increased relative to controls using semiquantitative histological analyses. The StrepH-related accumulation of K10 protein and profilaggrin/filaggrin were confirmed by Western analyses. Thus, it appears that the presence of intercellular HA in the epidermis acts as a brake upon intracellular events that occur during keratinocyte differentiation.
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, University of Insubria, Varese, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Passi
authors.forename: Parrish
authors.initials: P
authors.lastname: Sadeghi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kawamura
authors.forename: Sanjay
authors.initials: S
authors.lastname: Anand
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Sato
authors.forename: Laura E
authors.initials: LE
authors.lastname: White
authors.forename: Vincent C
authors.initials: VC
authors.lastname: Hascall
authors.forename: Edward V
authors.initials: EV
authors.lastname: Maytin
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D002478:Cells, Cultured; D000078404:Epidermal Cells; D004817:Epidermis / Q000254:growth & development; D000091344:Filaggrin Proteins; D006820:Hyaluronic Acid / Q000032:analysis / Q000502:physiology*; D006821:Hyaluronoglucosaminidase / Q000494:pharmacology; D007381:Intermediate Filament Proteins / Q000032:analysis; D053550:Keratin-10; D015603:Keratinocytes / Q000166:cytology*; D007633:Keratins / Q000032:analysis; D011498:Protein Precursors / Q000032:analysis; D051381:Rats; D013997:Time Factors
chemical_list: D015415:Biomarkers; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D011498:Protein Precursors; C001500:keratohyalin; D053550:Keratin-10; D007633:Keratins; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase