Molecular mechanisms for active DNA demethylation in cellular immune models

Abstract

[eng] Secondly, we also explored the role of DNA demethylation in the regulation of immunosuppressive phenotype of monocyte- (MO) derived dendritic cells (DC) differentiated in presence of vitamin D, focusing on the interplay among different signal-dependent transcription factors (TF) and the DNA demethylation machinery. In this study, we performed high-throughput DNA methylation screening of both inflammatory DCs and DCs differentiated in presence of vitamin D (TL). DNA methylation analysis revealed extensive condition-specific DNA demethylation events associated with differential immune properties. As expected, we observed that demethylation occurs in enhancer regions and displays an inverse correlation with gene expression. We proved that, vitamin D receptor (VDR) can bind to closed chromatin and correlates with TL-specific demethylation. Interestingly, we observed that tolerogenic properties in DCs are acquired together with activation of the IL- 6/JAK/STAT3 pathway. In fact, VDR directly binds the IL-6 gene and JAK2- mediated STAT3 phosphorylation is specific to vitamin D-stimulation. In addition, we also observed that VDR interacts with both STAT3 and TET2. Finally, we reported that pharmacological inhibition of STAT3 phosphorylation reverts the vitamin–induced tolerogenic properties of DCs.