Comparison of DNA Methylation and Expression Pattern of S100 and Other Epidermal Differentiation Complex Genes in Differentiating Keratinocytes.

Epidermal Differentiation Complex (EDC) is a gene cluster on human chromosome 1 q21, which comprises genes encoding four protein families: S100, S100 fused (SFTP), small proline-rich region (SPRR) and late cornified envelope (LCE) proteins. Contrary to the latter three families, which group proteins important for skin barrier formation, the role of S100 proteins has not been well defined and there are no systematic comparative data concerning their expression in the epidermis. Furthermore, little is known about epigenetic mechanisms controlling changes in S100 and other EDC genes expression in differentiating epidermis. In our study, using real-time PCR, we followed the expression of nine S100 genes at subsequent stages of differentiation of primary human keratinocytes and found that they exhibited different expression patterns. Then, we confronted the expression level in undifferentiated and differentiated keratinocytes with the extent of DNA methylation within their promoter or intragenic regions assessed by bisulfite sequencing. Methylation analysis was also performed for three other EDC genes of known expression pattern (involucrin, loricrin, and NICE-1) and a recently identified evolutionary conserved region with defined enhancer properties. The results indicate that altered EDC genes expression is not accompanied by major changes in DNA methylation.