A 4kb Fragment of the Desmocollin 3 Promoter Directs Reporter Gene Expression to Parakeratotic Epidermis and Primary Hair Follicles

The study identified a 4kb fragment of the desmocollin 3 (Dsc3) promoter that directed the expression of a β-galactosidase reporter gene specifically to parakeratotic epidermis and the bulb region of primary hair follicles in transgenic mice. This expression pattern was distinct from the native Dsc3, which was present in both parakeratotic and orthokeratotic epidermis. The findings suggested that the 4kb promoter fragment contained elements responsible for tissue-specific expression, but not all necessary regulatory elements for full expression patterns. The study provided early evidence for a transgene marker for parakeratotic epidermis, potentially useful for studying differentiation programs and testing antipsoriatic drugs.