Hyaluronan metabolism enhanced during epidermal differentiation is suppressed by vitamin C

Abstract

Background

Hyaluronan is a large, linear glycosaminoglycan present throughout the narrow extracellular space of the vital epidermis. Increased hyaluronan metabolism takes place in epidermal hypertrophy, wound healing and cancer. Hyaluronan is produced by hyaluronan synthases (HAS1-3) and catabolized by hyaluronidases (HYAL1 and -2), reactive oxygen species (ROS), and the KIAA1199 protein.

Objectives

To investigate the changes in hyaluronan metabolism during epidermal stratification and maturation, and the impact of vitamin C.

Methods

Hyaluronan synthesis and expression of the hyaluronan-related genes were analyzed during epidermal maturation from a simple epithelium to a fully differentiated epidermis in organotypic cultures of rat epidermal keratinocytes (REK) using qRT-PCR, immunostainings, and western blotting, in the presence and absence of vitamin C.

Results

With epidermal stratification, both the production and the degradation of hyaluronan were enhanced, resulting in an increase of hyaluronan fragments of various sizes. While the mRNA levels of Has3 and KIAA1199 remained stable during the maturation, Has1, Has2, and Hyal2 showed a transient upregulation during stratification, Hyal1 remained permanently increased, and the hyaluronan receptor Cd44 decreased. At maturation, Vitamin C downregulated Has2, Hyal2 and Cd44, while it increased high molecular mass hyaluronan in the epidermis, and reduced small fragments in the medium, suggesting stabilization of epidermal hyaluronan.

Conclusions

Epidermal stratification and maturation is associated with enhanced hyaluronan turnover, and release of large amounts of hyaluronan fragments. The high turnover is suppressed by vitamin C, which is suggested to enhance normal epidermal differentiation in part through its effect on hyaluronan.

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