title: Histone deacetylase 9 activates gamma-globin gene expression in primary erythroid cells.
abstract: Strategies to induce fetal hemoglobin (HbF) synthesis for the treatment of β-hemoglobinopathies probably involve protein modifications by histone deacetylases (HDACs) that mediate γ-globin gene regulation. However, the role of individual HDACs in globin gene expression is not very well understood; thus, the focus of our study was to identify HDACs involved in γ-globin activation. K562 erythroleukemia cells treated with the HbF inducers hemin, trichostatin A, and sodium butyrate had significantly reduced mRNA levels of HDAC9 and its splice variant histone deacetylase-related protein. Subsequently, HDAC9 gene knockdown produced dose-dependent γ-globin gene silencing over an 80-320 nm range. Enforced expression with the pTarget-HDAC9 vector produced a dose-dependent 2.5-fold increase in γ-globin mRNA (p < 0.05). Furthermore, ChIP assays showed HDAC9 binding in vivo in the upstream Gγ-globin gene promoter region. To determine the physiological relevance of these findings, human primary erythroid progenitors were treated with HDAC9 siRNA; we observed 40 and 60% γ-globin gene silencing in day 11 (early) and day 28 (late) progenitors. Moreover, enforced HDAC9 expression increased γ-globin mRNA levels by 2.5-fold with a simultaneous 7-fold increase in HbF. Collectively, these data support a positive role for HDAC9 in γ-globin gene regulation.
authors.affiliation: Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, Texas 75080, USA.
authors.forename: Shalini A
authors.initials: SA
authors.lastname: Muralidhar
authors.forename: Valya
authors.initials: V
authors.lastname: Ramakrishnan
authors.forename: Inderdeep S
authors.initials: IS
authors.lastname: Kalra
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Betty S
authors.initials: BS
authors.lastname: Pace
mesh_terms: D002087:Butyrates / Q000494:pharmacology; D041905:Erythroid Cells / Q000378:metabolism*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects; D006427:Hemin / Q000494:pharmacology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D020014:K562 Cells; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D055545:gamma-Globins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D002087:Butyrates; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D012097:Repressor Proteins; D055545:gamma-Globins; C012589:trichostatin A; D006427:Hemin; C486544:HDAC9 protein, human; D006655:Histone Deacetylases