Gene expression analysis of hematopoetic progenitors

Bivalency has been postulated to be a ‘poised’ state from which removal of one or the other mark permits gene activation or repression. To determine whether gene expression changes accompanied resolution of bivalent genes, we first obtained the expression pattern of hematopoietic stem cells (HSC), lymphoid-primed multipotent progenitors (LMPP), common lymphoid progenitors (CLP) , early thymic precursors (ETP), double negative 2 (DN2) and double negative 3 (DN3) cells using Affymetrix arrays. Consistent with trends noted in earlier studies, K4+ genes were, on average, expressed at higher levels compared to K4+K27+ or K27+ genes in all subsets. Hematopoietic stem cells (HSC), lymphoid-primed multipotent progenitors (LMPP) and common lymphoid progenitors (CLP) were purified from bone marrow of C57BL/6J mice; early thymic precursors (ETP), double negative 2 (DN2) and double negative 3 (DN3) cells were purified from C57BL6 thymus and used to obtained an expression pattern of each cell subset using Affymetrix arrays.