Induction of OCT2 contributes to regulate the gene expression program in human neutrophils activated via TLR8

The transcription factors (TFs) that regulate inducible genes in activated neutrophils are not yet completely characterized. Herein, we show that the genomic distribution of the histone modification H3K27Ac, as well as PU.1 and C/EBPβ, two myeloid-lineage-determining TFs (LDTFs), significantly changes in human neutrophils treated with R848, a ligand of Toll-like receptor 8 (TLR8). Interestingly, differentially acetylated and LDTF-marked regions reveal an over-representation of OCT-binding motifs that are selectively bound by OCT2/POU2F2. Analysis of OCT2 genomic distribution in primary neutrophils and of OCT2-depletion in HL-60-differentiated neutrophils proves the requirement for OCT2 in contributing to promote, along with nuclear factor κB (NF-κB) and activator protein 1 (AP-1), the TLR8-induced gene expression program in neutrophils. Altogether, our data demonstrate that neutrophils, upon activation via TLR8, profoundly reprogram their chromatin status, ultimately displaying cell-specific, prolonged transcriptome changes. Data also show an unexpected role for OCT2 in amplifying the transcriptional response to TLR8-mediated activation. [Display omitted] •Activation of neutrophils via TLR8 promotes a cell-specific transcriptional program•OCT motifs emerge from H3K27Ac, PU.1, and C/EBPβ ChIP-seq in R848-treated neutrophils•OCT motifs bind de novo synthesized OCT2 in TLR8-activated human neutrophils•OCT2 acts as a transcriptional amplifier in TLR8-activated human neutrophils Tamassia et al. report that activation of neutrophils via TLR8 promotes a cell-specific transcriptional program, as well as increased H3K27Ac levels and PU.1 and C/EBPβ DNA binding. By ChIP-seq, the authors also reveal a concomitant enrichment of OCT motifs to which de novo synthesized OCT2 binds and functions as a transcriptional amplifier.