title: Eos negatively regulates human γ-globin gene transcription during erythroid differentiation.
abstract: BACKGROUND
  Human globin gene expression is precisely regulated by a complicated network of transcription factors and chromatin modifying activities during development and erythropoiesis. Eos (Ikaros family zinc finger 4, IKZF4), a member of the zinc finger transcription factor Ikaros family, plays a pivotal role as a repressor of gene expression. The aim of this study was to examine the role of Eos in globin gene regulation.
  
  
  RESULTS
  Western blot and quantitative real-time PCR detected a gradual decrease in Eos expression during erythroid differentiation of hemin-induced K562 cells and Epo-induced CD34+ hematopoietic stem/progenitor cells (HPCs). DNA transfection and lentivirus-mediated gene transfer demonstrated that the enforced expression of Eos significantly represses the expression of γ-globin, but not other globin genes, in K562 cells and CD34+ HPCs. Consistent with a direct role of Eos in globin gene regulation, chromatin immunoprecipitaion and dual-luciferase reporter assays identified three discrete sites located in the DNase I hypersensitivity site 3 (HS3) of the β-globin locus control region (LCR), the promoter regions of the Gγ- and Aγ- globin genes, as functional binding sites of Eos protein. A chromosome conformation capture (3C) assay indicated that Eos may repress the interaction between the LCR and the γ-globin gene promoter. In addition, erythroid differentiation was inhibited by enforced expression of Eos in K562 cells and CD34+ HPCs.
  
  
  CONCLUSIONS
  Our results demonstrate that Eos plays an important role in the transcriptional regulation of the γ-globin gene during erythroid differentiation.
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Hai-Chuan
authors.initials: HC
authors.lastname: Yu
authors.forename: Hua-Lu
authors.initials: HL
authors.lastname: Zhao
authors.forename: Zhi-Kui
authors.initials: ZK
authors.lastname: Wu
authors.forename: Jun-Wu
authors.initials: JW
authors.lastname: Zhang
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002454:Cell Differentiation; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D041905:Erythroid Cells / Q000378:metabolism; D004920:Erythropoiesis / Q000502:physiology*; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D055545:gamma-Globins / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D055545:gamma-Globins; C477245:EOS serine protease, human; D012697:Serine Endopeptidases