Binding targets of transcription factor E2-2 in human plasmacytoid dendritic cells

The interferon-producing plasmacytoid dendritic cells (PDC) share common progenitors with antigen-presenting classical dendritic cells (cDC), yet they possess distinct morphology and molecular features resembling those of lymphocytes. It is unclear whether the unique cell fate of PDC is actively maintained in the steady state. We report that the deletion of transcription factor E2-2 from mature peripheral PDC caused their spontaneous differentiation into cells with cDC properties. This included the loss of PDC markers, increase in MHC class II expression and T cell priming capacity, acquisition of dendritic morphology and induction of cDC signature genes. Genome-wide chromatin immunoprecipitation revealed direct binding of E2-2 to key PDC-specific and lymphoid genes, as well as to certain genes enriched in cDC. Thus, E2-2 actively maintains the cell fate of mature PDC and opposes the “default” cDC fate, in part through direct regulation of lineage-specific gene expression programs. Cells of the human PDC lymphoma line CAL-1 (Maeda et al., Int J Hematol 2005) were crosslinked with formaldehyde, sonicated, and subjected to immunoprecipitation with anti-E2-2 mAb (Bain et al., Mol Cell Biol 1993) or mouse IgG control as described (Cisse et al., Cell 2008). After crosslink reversal, the isolated chromatin was amplified, labeled and hybridized to Human Promoter ChIP-on-chip Microarray Set (Agilent Technologies). Hybridized microarrays were scanned and analyzed using DNA Analytics software (Agilent Technologies).