title: RUNX1 DNA-binding mutants, associated with minimally differentiated acute myelogenous leukemia, disrupt myeloid differentiation.
abstract: Mutations in the RUNX1 gene are found at high frequencies in minimally differentiated acute myelogenous leukemia. In addition to null mutations, many of the mutations generate Runx1 DNA-binding (RDB) mutants. To determine if these mutants antagonize wild-type protein activity, cDNAs were transduced into murine bone marrow or human cord blood cells using retroviral vectors. Significantly, the RDB mutants did not act in a transdominant fashion in vivo to disrupt Runx1 activity in either T-cell or platelet development, which are highly sensitive to Runx1 dosage. However, RDB mutant expression impaired expansion and differentiation of the erythroid compartment in which Runx1 expression is normally down-regulated, showing that a RDB-independent function is incompatible with erythroid differentiation. Significantly, both bone marrow progenitors expressing RDB mutants or deficient for Runx1 showed increased replating efficiencies in vitro, accompanied by the accumulation of myeloblasts and dysplastic progenitors, but the effect was more pronounced in RDB cultures. Disruption of the interface that binds CBFbeta, an important cofactor of Runx1, did not impair RDB mutant replating activity, arguing against inactivation of Runx1 function by CBFbeta sequestration. We propose that RDB mutants antagonize Runx1 function in early progenitors by disrupting a critical balance between DNA-binding-independent and DNA-binding-dependent signaling.
authors.affiliation: Heinrich-Pette-Institut, Hamburg, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Cammenga
authors.forename: Birte
authors.initials: B
authors.lastname: Niebuhr
authors.forename: Stefan
authors.initials: S
authors.lastname: Horn
authors.forename: Ulla
authors.initials: U
authors.lastname: Bergholz
authors.forename: Gabriele
authors.initials: G
authors.lastname: Putz
authors.forename: Frank
authors.initials: F
authors.lastname: Buchholz
authors.forename: Jürgen
authors.initials: J
authors.lastname: Löhler
authors.forename: Carol
authors.initials: C
authors.lastname: Stocking
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D050676:Core Binding Factor Alpha 2 Subunit / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D050658:Core Binding Factor beta Subunit / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D004920:Erythropoiesis / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D006410:Hematopoiesis / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed; D012190:Retroviridae / Q000235:genetics; D014161:Transduction, Genetic
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; D050658:Core Binding Factor beta Subunit; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C493728:RUNX1 protein, human