Demethylase Kdm6a epigenetically promotes IL-6 and IFN-β production in macrophages

Molecular regulation of innate signal-initiated proinflammatory cytokine production has been extensively investigated. However, the roles of epigenetic modifiers and their underlying mechanisms in regulating innate inflammatory response and development of autoimmune diseases need to be further understood. Demethylase Kdm6a promotes gene transcription in cell-lineage specification through demethylating histone H3 lysine di/tri-methylation (H3K27me2/3), and loss of Kdm6a results in developmental defects. However, the function of Kdm6a in innate immunity and inflammation remains largely unknown. Here we found that Kdm6a, significantly downregulated via JNK pathway upon innate stimuli, promotes cytokine IL-6 and IFN-β transcription in primary macrophages during innate response. Kdm6a promoted IL-6 expression through demethylating H3K27me3 at promoter in a demethylase enzymatic activity-dependent manner. Interestingly, Kdm6a promoted IFN-β expression independent of its demethylase enzymatic activity, but through increasing transcription of IFN-β-specific enhancer-derived RNA (eRNA) S-IRE1. For the underlying mechanism, Kdm6a interacted with MLL4 and promoted MLL4 recruitment and H3K4me2 level in S-IRE1 region of Ifnb1 gene for full activation of enhancer. Our results reveal a previously unknown role of kdm6a in promoting innate IFN-β gene transcription at enhancer, in addition to demethylation at promoter. The function of Kdm6a in promoting innate inflammatory response also adds insights to better understanding of epigenetic modifiers in inflammatory and autoimmune disease.