Expression of peroxisome proliferator-activated receptor and CCAAT/ enhancer binding protein transcription factors in cultured human sebocytes

Lipid synthesis and accumulation represent a major step in sebocyte differentiation and it may be of importance for sebocytes to express two families of transcription factors, CCAAT/enhancer binding proteins (c/EBPs) and peroxisome proliferator-activated receptors (PPARs), which were found to play a crucial role in the differentiation of adipocytes. Using the immortalized human sebaceous gland cell line SZ95 we examined the expression of the molecules before and after treatment with testosterone, 5α-dihydrotestosterone, dexamethasone, 17β-estradiol and genistein, at 6, 12, 24, and 48 h, respectively. Reverse transcription-PCR analysis showed expression of peroxisome proliferator-activated receptors -α, -δ, -γ1, -γ2 and CCAAT/enhancer binding proteins-α, -β, -γ -δ in native SZ95 sebocytes. In western blot studies, high levels of CCAAT/enhancer binding proteins-α and -β, and peroxisome proliferator-activated receptors-γ were expressed at 6, 24, and 12 h, respectively. Immunostaining of the cultured sebocytes showed the CCAAT/ enhancer binding proteins-α and -β mainly localized within nuclei, whereas peroxisome proliferator-activated receptors-γ in the cytoplasm. Strong staining of sebocytes was immunohistochemically revealed in the basal layer of sebaceous glands in human scalp and sebaceous nevus. Genistein down-regulated the expression of CCAAT/enhancer binding proteins-α and -β, and peroxisome proliferator-activated receptors-γ on the protein level. Treatment with linoleic acid for 48 h induced further differentiation of sebocytes leading to abundant lipid synthesis.