PU.1 regulates both cytokine-dependent proliferation and differentiation of granulocyte/macrophage progenitors.
PU.1 is a unique regulatory protein required for the generation of both the innate and the adaptive immune system. It functions exclusively in a cell-intrinsic manner to control the development of granulocytes, macrophages, and B and T lymphocytes. We demonstrate that mutation of the PU.1 gene causes a severe reduction in myeloid (granulocyte/macrophage) progenitors. PU.1 -/- myeloid progenitors can proliferate in vitro in response to the multilineage cytokines interleukin-3 (IL-3), IL-6 and stem cell factor but are unresponsive to the myeloid-specific cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF and M-CSF. The failure of PU.1 -/- progenitors to respond to G-CSF is bypassed by transient signaling with IL-3. In the presence of IL-3 and G-CSF, PU.1 -/- progenitors can differentiate into granulocytic precursors containing myeloperoxidase-positive granules. Thus PU.1 is not essential for specification of granulocytic precursors, but is required for their further differentiation. The failure of PU.1 -/- progenitors to respond to M-CSF is due to lack of c-fms gene transcription. Transduction of c-fms into PU.1 -/- myeloid progenitors bypasses the block to M-CSF-dependent proliferation but does not induce detectable macrophage differentiation. Therefore, PU. 1 appears to be essential for specification of monocytic precursors. Importantly, retroviral transduction of PU.1 into mutant progenitors restores responsiveness to myeloid-specific cytokines and development of mature granulocytes and macrophages. Thus PU.1 controls myelopoiesis by regulating both proliferation and differentiation pathways.
DeKoter
R P
RP
Department of Molecular Genetics and Cell Biology, The University of Chicago, IL 60637, USA.
Walsh
J C
JC
Singh
H
H
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D003114:Colony-Forming Units Assay; D016207:Cytokines / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D016236:Genes, fms / Q000235:genetics; D016179:Granulocyte Colony-Stimulating Factor / Q000502:physiology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000502:physiology; D006098:Granulocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D007377:Interleukin-3 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D016173:Macrophage Colony-Stimulating Factor / Q000502:physiology; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D012190:Retroviridae / Q000235:genetics; D019089:Stem Cell Factor / Q000494:pharmacology; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D014161:Transduction, Genetic; D000099232:Proto-Oncogene Protein Spi-1
D016207:Cytokines; D016179:Granulocyte Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D007377:Interleukin-3; D015850:Interleukin-6; D016173:Macrophage Colony-Stimulating Factor; D011518:Proto-Oncogene Proteins; D019089:Stem Cell Factor; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1