Keratinocyte Growth Factor Stimulates Migration and Hyaluronan Synthesis in the Epidermis by Activation of Keratinocyte Hyaluronan Synthases 2 and 3

Abstract

Keratinocyte growth factor (KGF) activates keratinocyte migration and stimulates wound healing. Hyaluronan, an extracellular matrix glycosaminoglycan that accumulates in wounded epidermis, is known to promote cell migration, suggesting that increased synthesis of hyaluronan might be associated with the KGF response in keratinocytes. Treatment of monolayer cultures of rat epidermal keratinocytes led to an elongated and lifted cell shape, increased filopodial protrusions, enhanced cell migration, accumulation of intermediate size hyaluronan in the culture medium and within keratinocytes, and a rapid increase of hyaluronan synthase 2 (Has2) mRNA, suggesting a direct influence on this gene. In stratified, organotypic cultures of the same cell line, both Has2 and Has3 with the hyaluronan receptor CD44 were up-regulated and hyaluronan accumulated in the epidermis, the spinous cell layer in particular. At the same time the expression of the early differentiation marker keratin 10 was inhibited, whereas filaggrin expression and epidermal permeability were less affected. The data indicate that Has2 and Has3 belong to the targets of KGF in keratinocytes, and support the idea that enhanced hyaluronan synthesis acts an effector for the migratory response of keratinocytes in wound healing, whereas it may delay keratinocyte terminal differentiation.

Cellular Content of UDP-N-acetylhexosamines Controls Hyaluronan Synthase 2 Expression and Correlates with O-Linked N-Acetylglucosamine Modification of Transcription Factors YY1 and SP1

“…The synthesis of hyaluronan by epidermal keratinocytes and its content are tightly controlled by local growth factors such as heparin-binding EGF (50) and keratinocyte growth factor (13) and systemic effectors such as cortisol (51) and retinoids (9,11,16,52). Our results suggest that the metabolic state of the keratinocytes also contributes to the regulation of epidermal hyaluronan at both the substrate and gene expression levels.…”

“…ELISA for Hyaluronan-Media from the cultures were assayed for the concentration of hyaluronan using a sandwichtype ELISA as described previously (13,18).…”

“…Of the three genes, particularly HAS2 is subject to regulation by growth factors, cytokines, and hormones (4,14,15). In keratinocyte cultures, EGF, keratinocyte growth factor, TNF␣, and retinoic acid induce, whereas TGF␤ inhibits, HAS2 expression (8,10,13,16). Accordingly, the HAS2 promoter has been shown to contain functional response elements (REs) 3 for different transcription factors, including retinoid acid receptor, NF-B, CREB1 (cAMP response elementbinding protein 1), and SP1 (specificity protein 1) (7,11,16).…”

“…Changes in hyaluronan production have been associated mostly with the expression level of HAS genes (3-6), especially in keratinocytes (7)(8)(9)(10)(11)(12)(13). Of the three genes, particularly HAS2 is subject to regulation by growth factors, cytokines, and hormones (4,14,15).…”

Plasma Membrane Residence of Hyaluronan Synthase Is Coupled to Its Enzymatic Activity

“…This time was consistent with the 4 -5-h total turnover time of the GFP-HAS3, suggested by the cycloheximide experiments, and also with the steady state distribution of the GFP signal in the different compartments of REKs. Assuming a chain elongation rate of three monosaccharides/s (32), ϳ3 h would be required for the synthesis of a 6 ϫ 10 6 Da hyaluronan polymer, the size found in REKs (33). Based on these estimates, each HAS protein synthesizes only one hyaluronan chain in REKs, as also suggested by Ref.…”