Transcription profiling of mouse normal LT-HSC vs ST-HSC

Self-renewal is a defining characteristic of stem cells, however the molecular pathways underlying its regulation are poorly understood. Here we demonstrate that conditional inactivation of the Pbx1 proto-oncogene in the hematopoietic compartment results in a progressive loss of long-term hematopoietic stem cells (LT-HSCs) that is associated with concomitant reduction in their quiescence, leading to a defect in the maintenance of self-renewal as assessed by serial transplantation. Transcriptional profiling revealed that multiple stem cell maintenance factors are perturbed in Pbx1-deficient LT-HSCs, which prematurely express a large subset of genes, including cell cycle regulators, normally expressed in non-self-renewing multipotent progenitors. Experiment Overall Design: LT-HSC (Lin-cKit+Sca1+CD34-CD135-) and ST-HSC (Lin-cKit+Sca1+CD34+CD135-) cells were prospectively sorted from the BM of MxCre-.Pbx1f/f control mice harvested 4 weeks after the last injection of poly(I:C).