title: The Wilms' tumor suppressor Wt1 activates transcription of the erythropoietin receptor in hematopoietic progenitor cells.
abstract: The Wilms' tumor protein Wt1 is required for embryonic development and has been implicated in hematologic disorders. Since Wt1 deficiency may compromise the proliferation and differentiation of erythroid progenitor cells, we analyzed the possible role of the transcriptionally active Wt1 isoform, Wt1(-KTS), in regulating the expression of the erythropoietin receptor (EpoR). Wt1 and EpoR were coexpressed in CD117(+) hematopoietic progenitor cells and in several hematopoietic cell lines. CD117(+) cells of Wt1-deficient murine embryos (Wt1(-/-)) exhibited a significantly lower proliferation response to recombinant erythropoietin than CD117(+) cells of heterozygous (Wt1(+/-)) and wild-type littermates (Wt1(+/+)). EpoR expression was significantly diminished in hematopoietic progenitors (CD117(+)) that lacked Wt1, and the erythroid colony-forming capacity was reduced by more than 50% in fetal liver cells of Wt1-deficient embryonic mice. Wt1(-KTS) significantly increased endogenous EpoR transcripts in transfected cells. The proximal EpoR promoter of human and mouse was stimulated more than 10-fold by Wt1(-KTS) in transiently cotransfeced K562 erythroleukemia cells. A responsible cis-element, which is highly conserved in the EpoR promoter of human and mouse, was identified by mutation analysis, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay. In conclusion, activation of the EpoR gene by Wt1 may represent an important mechanism in normal hematopoiesis.
authors.affiliation: Institut für Vegetative Physiologie, Campus Virchow-Klinikum, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany.
authors.forename: Karin M
authors.initials: KM
authors.lastname: Kirschner
authors.forename: Patricia
authors.initials: P
authors.lastname: Hagen
authors.forename: Christiane S
authors.initials: CS
authors.lastname: Hussels
authors.forename: Matthias
authors.initials: M
authors.lastname: Ballmaier
authors.forename: Holger
authors.initials: H
authors.lastname: Scholz
authors.forename: Christof
authors.initials: C
authors.lastname: Dame
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D053595:Embryonic Stem Cells / Q000378:metabolism; D004920:Erythropoiesis / Q000235:genetics; D004921:Erythropoietin / Q000494:pharmacology; D017930:Genes, Reporter; D016162:Genes, Wilms Tumor; D006410:Hematopoiesis / Q000187:drug effects / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006579:Heterozygote; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017467:Receptors, Erythropoietin / Q000172:deficiency / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D025721:WT1 Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D017467:Receptors, Erythropoietin; D011994:Recombinant Proteins; D025721:WT1 Proteins; D004921:Erythropoietin; D004247:DNA; D019009:Proto-Oncogene Proteins c-kit