Aid is a key regulator of myeloid/erythroid differentiation and DNA methylation in murine hematopoietic stem/progenitor cells (ERRBS)

Recent studies have uncovered that activation-induced cytidine deaminase (AID) and ten-eleven-translocation (TET) family members regulate active DNA demethylation. Genetic alterations of TET2 in various myeloid malignancies and aberrant hematopoietic stem cell (HSC) self-renewal/differentiation in mice with hematopoietic tissue specific loss of Tet2 have been reported, indicating that TET2 is a master regulator of normal and malignant hematopoiesis. Despite a functional link between AID and TET in epigenetic gene regulation, the role of AID loss in normal hematopoiesis and myeloid transformation remains to be investigated. Here, we show that Aid loss in mice leads to expansion of myeloid cells and contraction in erythroid progenitors resulting in pathologic anemia possibly due to dysregulated expression of Cebpa and Gata1, myeloid/erythroid lineage specific transcription factors. Consistent with data in the murine context, silencing of AID skews differentiation towards myelomonocytic lineage in human BM cells. However, in contrast to Tet2, Aid loss does not contribute to enhanced HSC self-renewal or cooperate with Flt3-ITD in myeloid leukemogenesis. Genome-wide transcription and differential methylation analysis uncover critical role of Aid as a key epigenetic regulator. These results indicate that AID and TET2 share common effects on myeloid and erythroid lineage differentiation, and that their role is non-redundant in regulating HSC self-renewal and in myeloid transformation. Overall design: We utilized germ line Aid knockout mice for our study and examined transcriptome of FACS-sorted LSK populations from WT, Aid(+/-) and Aid(-/-) animals at 12 months of age.