Heterogeneity and quantitative differences of type 1 5 alpha-reductase expression in cultured skin epithelial cells.

Steroid 5α-reductase is the enzyme that converts testosterone to 5α-dihydrotestosterone (DHT). Two isoenzymes have been identified, namely type 1 and type 2 [1]. The conversion of testosterone to DHT is irreversible and the androgenic potency of DHT was shown to be at least 2–5 times stronger than that of testosterone [2, 3]. The hyperactivity of this enzyme is, therefore, supposed to play an important role in the etiopathogenesis of many androgen-dependent skin disorders, such as acne, hirsutism, androgenetic alopecia and seborrhea. Since the 1950s, the relevant studies in the field of dermatology have been concentrating on two major subjects: (i) the androgen metabolism in the skin by incubating the skin specimens with radiolabeled testosterone [4–6] and (ii) the distribution or localization of the isoenzymes in the skin by using polyclonal or monoclonal antibodies on paraffin sections [7, 8]. However, the following issues remain not fully clarified: (i) the subcellular localization of the enzyme, (ii) the mRNA expression and (iii) the quantitative enzyme expression in different skin components or skin cells from different regions. In this study, by using skin epithelial cell cultures, we have demonstrated immunocytochemically the subcellular localization of type 1 5α-reductase in the cytoplasm/cell membrane compartment. Evidence of the protein heterogeneity was observed in Western blotting studies. Facial sebocytes were found to exhibit the most abundant type 1 5αreductase expression among cultured adult skin epithelial cells. Materials and Methods