Open AccessSilencing of Aγ-Globin Gene Expression during Adult Definitive Erythropoiesis Mediated by GATA-1-FOG-1-Mi2 Complex Binding at the −566 GATA Site
Author(s) -
Susanna Harju-Baker,
Flavia C Costa,
Halyna Fedosyuk,
Renee Neades,
Kenneth R. Peterson
Publication year - 2008
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.01858-07
Subject(s) - locus control region , biology , globin , gene silencing , microbiology and biotechnology , erythropoiesis , hypersensitive site , gene , chromosome conformation capture , chromatin , gata2 , gene expression , gata transcription factor , promoter , chromatin immunoprecipitation , regulation of gene expression , genetics , enhancer , medicine , anemia
Autonomous silencing of γ-globin transcription is an important developmental regulatory mechanism controlling globin gene switching. An adult stage-specific silencer of theA γ-globin gene was identified between −730 and −378 relative to the mRNA start site. A marked copy of theA γ-globin gene inserted between locus control region 5′ DNase I-hypersensitive site 1 and the ε-globin gene was transcriptionally silenced in adult β-globin locus yeast artificial chromosome (β-YAC) transgenic mice, but deletion of the 352-bp region restored expression. This fragment reduced reporter gene expression in K562 cells, and GATA-1 was shown to bind within this sequence at the −566 GATA site. Further, the Mi2 protein, a component of the NuRD complex, was observed in erythroid cells with low γ-globin levels, whereas only a weak signal was detected when γ-globin was expressed. Chromatin immunoprecipitation of fetal liver tissue from β-YAC transgenic mice demonstrated that GATA-1, FOG-1, and Mi2 were recruited to theA γ-globin −566 orG γ-globin −567 GATA site when γ-globin expression was low (day 18) but not when γ-globin was expressed (day 12). These data suggest that during definitive erythropoiesis, γ-globin gene expression is silenced, in part, by binding a protein complex containing GATA-1, FOG-1, and Mi2 at the −566/−567 GATA sites of the proximal γ-globin promoters.