Expression data from murine cell line transduced with epitope tagged forms of Hoxa9

Importantly increasing evidence shows that Hox genes such as Hoxa9 are key regulators of stem cell self-renewal and hematopoiesis. Hoxa9 is expressed in early hematopoietic progenitor cells and promotes stem cell expansion. In contrast Hoxa9 down regulation is associated with hematopoietic differentiation. In addition to its role in development, HOXA9 has been intensively studied because of its central role in human acute leukemias. Despite their obvious biomedical importance, the mechanisms through which Hoxa9 and its partner proteins exert their downstream functions are poorly understood. Using whole-genome gene expression profiling, we identified direct targets of Hoxa9 in murine MHPs after 4-OHT withdraw, resulting in cell differentiation. Bone marrow cells were harvested from 5-Fluorouracil treated female 6-8 week old C57BL/6 mice and transduced with an MSCV-based retrovirus expressing Hoxa9 fused to a modified estrogen receptor ligand binding domain (Hoxa9-ER). Hoxa9-ER cells were washed 3x and resuspended in IL-3+ media with/without 100 nM 4-OHT (Sigma). At selected intervals, cells were removed for flow cytometric analysis using anti-Gr1 and anti-Mac1 antibodies (BD biosciences), morphologic assessment by cytocentrifugation and staining with Diff-Quick reagents (Intl. Med. Equip.), and RNA collection. For RNA, Pellets were lysed in Trizol reagent (Invitrogen) and RNA was extracted following manufacturer's instructions until phase separation, after which RNeasy columns (Qiagen) were employed for further purification. cRNA probes were synthesized at the University of Michigan microarray core. Probes were hybridized to Affymetrix Mouse 430 2.0 array.