Kujiol A Inhibits Interferon-γ and Interleukin-2 Expression and the NFATc2 Interaction with Their Promoters in T Cells

Kujiol A is one of the kujigamberol-related compounds isolated from Kuji amber. We previously demonstrated that kujiol A exhibited multiple biological activities, including the inhibition of Ca2+ signal transduction. In the present study, we found that kujiol A prevented the transcription of interferon-γ (IFN-γ), interleukin (IL)-2, IL-4, and Fas ligand in T-box transcription factor Eomesodermin (Eomes)-transfected murine T cell lymphoma BW5147 cells stimulated with phorbol ester and ionomycin (a calcium ionophore). In the murine cytotoxic T cell line CTLL-2, kujiol A reduced ionomycin-induced increases in IFN-γ mRNA expression. Luciferase reporter assays revealed that kujiol A inhibited the transcriptional activities of nuclear factor of activated T cells (NFAT) and, to a lesser extent, nuclear factor κB in human embryonic kidney 293T cells. Kujiol A did not affect NFATc2 (also known as NFAT1) protein expression. However, a chromatin immunoprecipitation assay showed that kujiol A prevented the NFATc2 protein from interacting with the IFN-γ and IL-2 promoters in Eomes-transfected BW5147 cells. Collectively, these results demonstrate that kujiol A is a potent immunosuppressant that inhibits T cell cytokine expression by targeting the NFAT pathway.