RESUMO
The requirement of the transcription factor PU.1 for macrophage development has been well documented. However, the target genes regulated by PU.1 controlling macrophage maturation are not known. A granulocyte macrophage colony stimulating factor (GM-CSF)-dependent PU.1 null monocytic precursor cell was stably transduced with a PU.1-expressing retrovirus. The expression of PU.1 altered the surface expression of a few proteins expressed on monocytes; these cells, however, remained GM-CSF dependent and maintained an immature phenotype. In contrast to the PU.1 null cells, the cells expressing PU.1 responded to macrophage colony stimulating factor (M-CSF) with subsequent development into mature macrophages. Using suppressive subtractive hybridization between the PU.1 null and immature PU.1 rescued cells, three genes, MRP-14, Dap12 and CD53, were found expressed in the rescued cells, but not in the PU.1 null cells. In addition, these genes were modulated during M-CSF-induced maturation of the PU.1 rescued cells. The PU.1 null and rescued early monocytic cells provide a useful model to study the role of PU.1 in macrophage development.