CULTURED HUMAN KERATINOCYTES EXPRESS TROPOELASTIN

We detected elastin mRNA in cultured normal human keratinocytes by RNa se protection assay. The content of elastin mRNA was estimated at appr oximately one-twentieth of that of cultured skin fibroblasts. Tropoela stin polypeptide with a molecular weight of 68 kDa was detected in the preparation of culture medium of normal human keratinocytes by wester n blot assays using anti-tropoelastin antibody. Immunohistochemical st udies also demonstrated positive staining in cultured normal human ker atinocytes as well as in skin fibroblasts. The expression of elastin b y normal human keratinocytes was found to reach a maximum level at the quiescent phase of keratinocyte growth. When normal human keratinocyt es were cultured on tropoelastin-coated dishes, their growth potential was greatly suppressed compared with other matrix protein-coated dish es. These results suggest that cultured normal human keratinocytes can actively synthesize elastin and that keratinocyte elastin may act as a growth-regulator for keratinocytes.