title: Runx1 deletion or dominant inhibition reduces Cebpa transcription via conserved promoter and distal enhancer sites to favor monopoiesis over granulopoiesis.
abstract: Deletion of Runx1 in adult mice produces a myeloproliferative phenotype. We now find that Runx1 gene deletion increases marrow monocyte while reducing granulocyte progenitors and that exogenous RUNX1 rescues granulopoiesis. Deletion of Runx1 reduces Cebpa mRNA in lineage-negative marrow cells and in granulocyte-monocyte progenitors or common myeloid progenitors. Pu.1 mRNA is also decreased, but to a lesser extent. We also transduced marrow with dominant-inhibitory RUNX1a. As with Runx1 gene deletion, RUNX1a expands lineage-Sca-1+c-kit+ and myeloid cells, increased monocyte CFUs relative to granulocyte CFUs, and reduced Cebpa mRNA. Runx1 binds a conserved site in the Cebpa promoter and binds 4 sites in a conserved 450-bp region located at +37 kb; mutation of the enhancer sites reduces activity 6-fold in 32Dcl3 myeloid cells. Endogenous Runx1 binds the promoter and putative +37 kb enhancer as assessed by ChIP, and RUNX1-ER rapidly induces Cebpa mRNA in these cells, even in cycloheximide, consistent with direct gene regulation. The +37 kb region contains strong H3K4me1 histone modification and p300-binding, as often seen with enhancers. Finally, exogenous C/EBPα increases granulocyte relative to monocyte progenitors in Runx1-deleted marrow cells. Diminished CEBPA transcription and consequent impairment of myeloid differentiation may contribute to leukemic transformation in acute myeloid leukemia cases associated with decreased RUNX1 activity.
authors.affiliation: Division of Pediatric Oncology, Johns Hopkins University, Baltimore, MD 21231, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Guo
authors.forename: Ou
authors.initials: O
authors.lastname: Ma
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Speck
authors.forename: Alan D
authors.initials: AD
authors.lastname: Friedman
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics*; D002478:Cells, Cultured; D050676:Core Binding Factor Alpha 2 Subunit / Q000037:antagonists & inhibitors / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D017353:Gene Deletion; D005799:Genes, Dominant / Q000502:physiology; D006098:Granulocytes / Q000378:metabolism / Q000502:physiology; D057809:HEK293 Cells; D006410:Hematopoiesis / Q000235:genetics* / Q000502:physiology; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009000:Monocytes / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C530718:CEBPA protein, mouse; D050676:Core Binding Factor Alpha 2 Subunit; C493726:Runx1 protein, mouse