Regulation of CRABP II mRNA expression in human keratinocytes

Cultured human neonatal keratinocytes were used to study the mechanisms and factors involved in the regulation of CRABP II gene expression. Post-confluent, relatively differentiated keratinocyte cultures had higher levels of CRABP II mRNA, but nuclear run-on experiments detected no sustained increase in CRABP II gene transcription rate between pre-confluent and post-confluent cells. Also, our studies could detect no change in the long half-life (> 32 hours) of this message in pre- and post-confluent cultures. Hydrocortisone was found to reduce the confluency-related increase in CRABP II mRNA in keratinocyte cultures. Because corticosteroids are known to reduce the effect of various cytokines, a series of epidermal cytokines were examined for a modulating effect on CRABP II mRNA content in cultured keratinocytes. IL1 alpha produced the greatest increase and IL6 the strongest reduction in the level of this message in cells grown in serum-free, defined medium. These data support a role for CRABP II in the proliferation and differentiation of human keratinocytes and suggest that epidermal cytokines may at least in part regulate the expression of the CRABP II gene at the mRNA level.