Epigenetic Regulation of Filaggrin Gene Expression in Human Epidermal Keratinocytes

BACKGROUND: Loss-of-function mutations in the filaggrin gene (FLG), which encodes an epidermal protein crucial for the formation of a functional skin barrier, have been identified as a major predisposing factor in the etiopathogenesis of atopic dermatitis (AD). Recent reports of relatively low frequencies of FLG-null mutations among specific ethnic groups with AD necessitated analysis of the epigenetic regulation which may control FLG expression without altering its DNA sequence.OBJECTIVE: The study aimed to identify DNA methylation-dependent regulation of FLG expression.METHODS: Quantitative polymerase chain reaction was performed to determine the restoration of FLG mRNA expression in normal human epidermal keratinocyte (NHEK) cells after treatment with epigenetic modulating agents. Bisulfite genomic sequencing and pyrosequencing analyses of the FLG promoter region were conducted to identify the citical CpG sites relevant to FLG expression. We performed small-scale pilot study for epidermal tissues obtained from Korean patients with severe AD.RESULTS: We here show that DNA methylation in the FLG with non-CpG island promoter is responsible for the transcriptional regulation of FLG in undifferentiated NHEK cells. The methylation frequencies in a single CpG site of the FLG promoter were significantly higher in lesional epidermis than those in matched nonlesional epidermis of subjects with severe AD.CONCLUSION: Our in vitro and clinical studies point to this unique CpG site as a potential DNA methylation marker of FLG, which can be a promising therapeutic target in the complications of filaggrin-related skin barrier dysfunction as well as in AD.

Beta-Defensin 124 Is Required for Efficient Innate Immune Responses in Prostate Epithelial RWPE-1 Cells

PURPOSE: The present study aimed to determine the role played by beta-defensin 124 (DEFB124) in the innate immunity of prostate epithelial RWPE-1 cells during bacterial infection. MATERIALS AND METHODS: The expression of DEFB124 was examined by quantitative real-time polymerase chain reaction (PCR), Western blotting, and immunocytochemistry. Enzyme-linked immunosorbent assays and quantitative real-time PCR were performed to determine the production of cytokines and chemokines. Western blotting and chromatin immunoprecipitation studies were performed to assess the interaction between DEFB124 and nuclear factor-kappa B (NF-kappaB) in peptidoglycan (PGN)-stimulated RWPE-1 cells. By chemotaxis assay, we assessed the effect of DEFB124 on the migration of monocytes. RESULTS: Exposure to PGN induced DEFB124 upregulation and NF-kappaB activation through IkappaBalpha phosphorylation and IkappaBalpha degradation. Bay11-7082, an NF-kappaB inhibitor, blocked PGN-induced DEFB124 production. Also, NF-kappaB was shown to be a direct regulator and to directly bind to the -3.14 kb site of the DEFB124 promoter in PGN-treated human prostate epithelial RWPE-1 cells. When DEFB124 was overexpressed in RWPE-1 cells, interestingly, the production of cytokines (interleukin [IL] 6 and IL-12) and chemokines (CCL5, CCL22, and CXCL8) was significantly increased. These DEFB124-upregulated RWPE-1 cells markedly induced chemotactic activity for THP-1 monocytes. CONCLUSIONS: Taken together, these results provide strong evidence for the first time that increased DEFB124 expression via NF-kappaB activation in PGN-exposed RWPE-1 cells enhances the production of cytokines and chemokines, which may contribute to an efficient innate immune defense.