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Hematology - Molecular Biology

Gene Expression Profiling Identifies HOXB4 as a Direct Downstream Target of GATA-2 in Human CD34+ Hematopoietic Cells
Published: Monday, September 24, 2012
Author: Tohru Fujiwara et al.

by Tohru Fujiwara, Hisayuki Yokoyama, Yoko Okitsu, Mayumi Kamata, Noriko Fukuhara, Yasushi Onishi, Shinichi Fujimaki, Shinichiro Takahashi, Kenichi Ishizawa, Emery H. Bresnick, Hideo Harigae

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.