title: MBD2 contributes to developmental silencing of the human ε-globin gene.
abstract: During erythroid development, the embryonic ε-globin gene becomes silenced as erythropoiesis shifts from the yolk sac to the fetal liver where γ-globin gene expression predominates. Previous studies have shown that the ε-globin gene is autonomously silenced through promoter proximal cis-acting sequences in adult erythroid cells. We have shown a role for the methylcytosine binding domain protein 2 (MBD2) in the developmental silencing of the avian embryonic ρ-globin and human fetal γ-globin genes. To determine the roles of MBD2 and DNA methylation in human ε-globin gene silencing, transgenic mice containing all sequences extending from the 5' hypersensitive site 5 (HS5) of the β-globin locus LCR to the human γ-globin gene promoter were generated. These mice show correct developmental expression and autonomous silencing of the transgene. Either the absence of MBD2 or treatment with the DNA methyltransferase inhibitor 5-azacytidine increases ε-globin transgene expression by 15-20 fold in adult mice. Adult mice containing the entire human β-globin locus also show an increase in expression of both the ε-globin gene transgene and endogenous ε(Y) and β(H1) genes in the absence of MBD2. These results indicate that the human ε-globin gene is subject to multilayered silencing mediated in part by MBD2.
authors.affiliation: Massey Cancer Center, Virginia Commonwealth University, Richmond, USA. ruponj@email.chop.edu
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Rupon
authors.forename: Shou Zhen
authors.initials: SZ
authors.lastname: Wang
authors.forename: Merlin
authors.initials: M
authors.lastname: Gnanapragasam
authors.forename: Stefanos
authors.initials: S
authors.lastname: Labropoulos
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Ginder
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004900:Erythroblasts / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D023061:Gene Order; D020868:Gene Silencing; D006455:Hemoglobins, Abnormal / Q000378:metabolism; D006801:Humans; D019901:Locus Control Region / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D055544:beta-Globins / Q000378:metabolism; D055547:epsilon-Globins / Q000235:genetics*; D055545:gamma-Globins / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D006455:Hemoglobins, Abnormal; C115368:MBD2 protein; D055544:beta-Globins; D055547:epsilon-Globins; D055545:gamma-Globins; D001374:Azacitidine