Zeb1 Regulates the Function of Lympho-Myeloid Primed Progenitors after Transplantation

Zeb1, a zinc finger E-box binding homeobox epithelial-mesenchymal (EMT) transcription factor, acts as a critical regulator of hematopoietic stem cell (HSC) self-renewal and multi-lineage differentiation. Whether Zeb1 directly regulates the function of multi-potent progenitors primed for hematopoietic lineage commitment remains ill defined. By using an inducible Mx-1 Cre conditional mouse model where Zeb1 was genetically engineered to be deficient in the adult hematopoietic system (hereafter Zeb1^-/-), we found that the absolute cell number of immunophenotypically defined lympho-myeloid primed progenitors (LMPPs) from Zeb1^-/- mice was reduced. Myeloid- and lymphoid-biased HSCs in Zeb1^-/- mice were unchanged, implying that defective LMPP generation from Zeb1^-/- mice was not directly caused by an imbalance of lineage-biased HSCs. Functional analysis of LMPP from Zeb1^-/- mice, as judged by competitive transplantation, revealed an overall reduction in engraftment to hematopoietic organs over 4 weeks, which correlated with minimal T-cell engraftment, reduced B-cell and monocyte/macrophage engraftment, and unperturbed granulocyte engraftment. Thus, Zeb1 regulates LMPP differentiation potential to select lympho-myeloid lineages in the context of transplantation.