Mtg16 regulates E protein activity and lineage specification in dendritic cell development (gene expression)

E protein transcription factors specify major immune cell lineages including lymphocytes and interferon-producing plasmacytoid dendritic cells (pDCs). Corepressors of the ETO family can bind to and block transactivation by E proteins, but the physiological role of these interactions remained unclear. We report that ETO protein Mtg16 binds chromatin primarily through the pDC-specific E protein E2-2 in human pDCs. Mtg16-deficient mice showed impaired pDC development and functionality, whereas the specification of the classical dendritic cells (cDCs) was enhanced. The deletion of Mtg16 caused aberrant expression of E protein antagonist Id2 in pDCs. Thus, Mtg16 acts as a cofactor of E2-2 to promote pDC differentiation and restrict cDC development, revealing an unexpected positive role of ETO proteins in E protein activity. pDC from BM of WT and mtg16-KO mice were negatively selected (lin-CD19, Tcrb, Ter119, NK1.1) and sorted as CD11c+Bst2+ population directly in Trizol. RNA was prepared and deposited for microarray processing.