Expression data from control and Pbx1-null CMPs and GMPs

The capacity of the hematopoietic system to promptly respond to peripheral demands relies on adequate pools of progenitors able to transiently proliferate and differentiate in a regulated manner. However, little is known about factors that may restrain progenitor maturation to maintain their reservoirs. In addition to a profound defect in hematopoietic stem cell (HSC) self-renewal, conditional knockout mice for the Pbx1 proto-oncogene have a significant reduction in lineage-restricted progenitors, including common myeloid progenitors (CMPs) and, to a lesser extent, granulocyte-monocyte progenitors (GMPs). Through analysis of purified progenitor proliferation, differentiation capacity and transcriptional profiling, we demonstrate that in the absence of Pbx1 the CMP pool is reduced due to aberrantly rapid myeloid maturation, associated with decreased expression of Meis1 and its targets including Flt3. BM cells were obtained from multiple bones of individual three to five week old Tie2Cre+.Pbx1-/f or Tie2Cre+.Pbx1+/f control mice (4-5 biological replicates/group). CMPs and GMPs were sorted by flow cytometry according to the following markers: Lin-/c-Kit+/Sca-/CD34+/CD16/32int, and Lin-/c-Kit+/Sca-/CD34+/CD16/32high, respectively, prior to RNA extraction.