Interleukin-6 regulates human ODAM gene expression in gingival epithelial cells

Odontogenic ameloblast-associated protein (ODAM) is a small secretory protein produced by the junctional epithelium (JE) and mature ameloblasts. It plays a role in odontogenesis and mediates the adhesion of JE to enamel. We used human gingival epithelial cells to evaluate the mechanism of ODAM gene expression regulation in the JE by interleukin (IL)-6.

Ca9-22, Sa3, and HSY cells were stimulated with IL-6 (10 ng/mL), after which total RNA and proteins were extracted. Real-time polymerase chain reaction and Western blot analyses were performed to assess the expression levels of ODAM mRNA and protein. Luciferase (LUC) assays were employed using LUC constructs with varying lengths of the ODAM gene promoter sequence. Gel mobility shift and chromatin immunoprecipitation (ChIP) analyses were conducted to investigate the binding of transcription factors to response elements within the gene promoter.

Treatment with IL-6 increased the expressions of ODAM mRNA and protein. Additionally, it induced promoter activity of the ODAM gene, while LUC activity was suppressed by inhibitors of protein kinase A, tyrosine kinase, MEK1/2, phosphatidylinositol 3-kinase, nuclear factor-κB, signal transducer and activator of transcription (STAT) 3, and glycoprotein 130. Gel mobility shift and ChIP analyses revealed that IL-6 induced the binding of yin yang 1 (YY1), CCAAT/enhancer-binding protein (C/EBP) β, GATA binding protein (GATA), and phospho-STAT3 to the YY1, C/EBP, GATA, and interferon-γ activated transcriptional element (GATE) 1-3 elements.

These findings indicate that IL-6 upregulates ODAM gene expression by targeting the YY1, C/EBP, GATA, and GATE1-3 elements in the promoter region of the human ODAM gene.