title: Hyaluronan Does Not Regulate Human Epidermal Keratinocyte Proliferation and Differentiation.
abstract: Hyaluronan (HA) is synthesized by three HA synthases (HAS1, HAS2, and HAS3) and secreted in the extracellular matrix. In human skin, large amounts of HA are found in the dermis. HA is also synthesized by keratinocytes in the epidermis, although its epidermal functions are not clearly identified yet. To investigate HA functions, we studied the effects of HA depletion on human keratinocyte physiology within in vitro reconstructed human epidermis. Inhibition of HA synthesis with 4-methylumbelliferone (4MU) did not modify the expression profile of the epidermal differentiation markers involucrin, keratin 10, and filaggrin during tissue reconstruction. In contrast, when keratinocytes were incubated with 4MU, cell proliferation was decreased. In an attempt to rescue the proliferation function, HA samples of various mean molecular masses were added to keratinocyte cultures treated with 4MU. These samples were unable to rescue the initial proliferation rate. Furthermore, treatments with HA-specific hyaluronidase, although removing almost all HA from keratinocyte cultures, did not alter the differentiation or proliferation processes. The differences between 4MU and hyaluronidase effects did not result from differences in intracellular HA, sulfated glycosaminoglycan concentration, apoptosis, or levels of HA receptors, all of which remained unchanged. Similarly, knockdown of UDP-glucose 6-dehydrogenase (UGDH) using lentiviral shRNA effectively decreased HA production but did not affect proliferation rate. Overall, these data suggest that HA levels in the human epidermis are not directly correlated with keratinocyte proliferation and differentiation and that incubation of cells with 4MU cannot equate with HA removal.
authors.affiliation: From the URPHYM, NARILIS, University of Namur, B-5000 Namur, Belgium.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Malaisse
authors.affiliation: the UMR5165/U1056, CNRS-INSERM, University of Toulouse, UDEAR, 31013 Toulouse CEDEX 6, France, and.
authors.forename: Valérie
authors.initials: V
authors.lastname: Pendaries
authors.affiliation: the URVI, NARILIS, University of Namur, B-5000 Namur, Belgium.
authors.forename: Fanny
authors.initials: F
authors.lastname: Hontoir
authors.affiliation: From the URPHYM, NARILIS, University of Namur, B-5000 Namur, Belgium.
authors.forename: Valérie
authors.initials: V
authors.lastname: De Glas
authors.affiliation: From the URPHYM, NARILIS, University of Namur, B-5000 Namur, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Van Vlaender
authors.affiliation: the UMR5165/U1056, CNRS-INSERM, University of Toulouse, UDEAR, 31013 Toulouse CEDEX 6, France, and.
authors.forename: Michel
authors.initials: M
authors.lastname: Simon
authors.affiliation: From the URPHYM, NARILIS, University of Namur, B-5000 Namur, Belgium.
authors.forename: Catherine
authors.initials: C
authors.lastname: Lambert de Rouvroit
authors.affiliation: From the URPHYM, NARILIS, University of Namur, B-5000 Namur, Belgium.
authors.forename: Yves
authors.initials: Y
authors.lastname: Poumay
authors.affiliation: From the URPHYM, NARILIS, University of Namur, B-5000 Namur, Belgium, Bruno.Flamion@unamur.be.
authors.forename: Bruno
authors.initials: B
authors.lastname: Flamion
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D000078404:Epidermal Cells; D000091344:Filaggrin Proteins; D055785:Gene Knockdown Techniques; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism; D006820:Hyaluronic Acid / Q000737:chemistry / Q000502:physiology*; D006821:Hyaluronoglucosaminidase / Q000737:chemistry / Q000494:pharmacology; D015603:Keratinocytes / Q000502:physiology*; D008970:Molecular Weight
chemical_list: D001426:Bacterial Proteins; C497483:CD44 protein, human; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase
keywords: 4-methylumbelliferone; differentiation; epidermis; hyaluronan; hyaluronidase; keratinocyte; proliferation