Poster presentation, P113

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Depigmentation by keratinocyte-derived, Wnt inhibitor sFRP2

BACKGROUND: A link between Wnt/β-catenin signaling and melanocyte differentiation has been revealed by the finding that β-catenin forms a complex with lymphocyte enhancer factor-1 to up-regulate expression of the MITF gene. Also, β-catenin directly interacts with the MITF protein itself and then activates MITF-specific target genes. Conversely, the inhibitor for Wnt/β-catenin such as DKK1 is known to inhibit melanocyte growth and function. OBJECTIVES: In this study, we found that another Wnt/β-catenin inhibitor sFRP2 was increased in epidermis of palmoplantar skin. METHODS: To investigate the effect of sFRP2, we set the co-culture model in which HaCaT keratinocytes and melanocytes were incubated using Boyden’s chamber. After transduction of HaCaT with the recombinant adenovirus expressing sFRP2, cells were loaded into upper chamber, and melanocytes were seeded in lower chamber. Results: Interestinlgy, the β-catenin level was significantly decreased in melanocytes by co-culture with sFRP2 overexpressing HaCaT cells. In addition, the protein levels for pigmentation-related molecules including MITF and TYR were also down-regulated by co-culture with sFRP2 overexpressing HaCaT. CONCLUSIONS: These results suggest that increase of sFRP2 in epidermal keratinocytes of palmoplantar skin comparing to trunk (or non-palmoplantar) one may decrease the melanogenic potential of melanocytes, contributing the depigmentation and relate clinically with the whitening of the palmoplantar areas.

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