title: Gene expression profiling identifies HOXB4 as a direct downstream target of GATA-2 in human CD34+ hematopoietic cells.
abstract: Aplastic anemia is characterized by a reduced hematopoietic stem cell number. Although GATA-2 expression was reported to be decreased in CD34-positive cells in aplastic anemia, many questions remain regarding the intrinsic characteristics of hematopoietic stem cells in this disease. In this study, we identified HOXB4 as a downstream target of GATA-2 based on expression profiling with human cord blood-derived CD34-positive cells infected with control or GATA-2 lentiviral shRNA. To confirm the functional link between GATA-2 and HOXB4, we conducted GATA-2 gain-of-function and loss-of-function experiments, and HOXB4 promoter analysis, including luciferase assay, in vitro DNA binding analysis and quantitative ChIP analysis, using K562 and CD34-positive cells. The analyses suggested that GATA-2 directly regulates HOXB4 expression through the GATA sequence in the promoter region. Furthermore, we assessed GATA-2 and HOXB4 expression in CD34-positive cells from patients with aplastic anemia (n = 10) and idiopathic thrombocytopenic purpura (n = 13), and demonstrated that the expression levels of HOXB4 and GATA-2 were correlated in these populations (r = 0.6573, p<0.01). Our results suggested that GATA-2 directly regulates HOXB4 expression in hematopoietic stem cells, which may play an important role in the development and/or progression of aplastic anemia.
authors.affiliation: Molecular Hematology/Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Yokoyama
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okitsu
authors.forename: Mayumi
authors.initials: M
authors.lastname: Kamata
authors.forename: Noriko
authors.initials: N
authors.lastname: Fukuhara
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Onishi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Fujimaki
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Takahashi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishizawa
authors.forename: Emery H
authors.initials: EH
authors.lastname: Bresnick
authors.forename: Hideo
authors.initials: H
authors.lastname: Harigae
mesh_terms: D000741:Anemia, Aplastic / Q000235:genetics / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism*; D001483:Base Sequence; D050989:GATA2 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D018952:Antigens, CD34; D050989:GATA2 Transcription Factor; C090460:HOXB4 protein, human; D018398:Homeodomain Proteins; D014157:Transcription Factors