title: Inhibition of G9a methyltransferase stimulates fetal hemoglobin production by facilitating LCR/γ-globin looping.
abstract: Induction of fetal hemoglobin (HbF) production in adult erythrocytes can reduce the severity of sickle cell disease and β-thalassemia. Transcription of β-globin genes is regulated by the distant locus control region (LCR), which is brought into direct gene contact by the LDB1/GATA-1/TAL1/LMO2-containing complex. Inhibition of G9a H3K9 methyltransferase by the chemical compound UNC0638 activates fetal and represses adult β-globin gene expression in adult human hematopoietic precursor cells, but the underlying mechanisms are unclear. Here we studied UNC0638 effects on β-globin gene expression using ex vivo differentiation of CD34(+) erythroid progenitor cells from peripheral blood of healthy adult donors. UNC0638 inhibition of G9a caused dosed accumulation of HbF up to 30% of total hemoglobin in differentiated cells. Elevation of HbF was associated with significant activation of fetal γ-globin and repression of adult β-globin transcription. Changes in gene expression were associated with widespread loss of H3K9me2 in the locus and gain of LDB1 complex occupancy at the γ-globin promoters as well as de novo formation of LCR/γ-globin contacts. Our findings demonstrate that G9a establishes epigenetic conditions preventing activation of γ-globin genes during differentiation of adult erythroid progenitor cells. In this view, manipulation of G9a represents a promising epigenetic approach for treatment of β-hemoglobinopathies.
authors.affiliation: Laboratory of Cellular and Developmental Biology, and.
authors.forename: Ivan
authors.initials: I
authors.lastname: Krivega
authors.affiliation: Molecular Genomics and Therapeutics Section, Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
authors.forename: Colleen
authors.initials: C
authors.lastname: Byrnes
authors.affiliation: Molecular Genomics and Therapeutics Section, Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
authors.forename: Jaira F
authors.initials: JF
authors.lastname: de Vasconcellos
authors.affiliation: Molecular Genomics and Therapeutics Section, Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
authors.forename: Y Terry
authors.initials: YT
authors.lastname: Lee
authors.affiliation: Molecular Genomics and Therapeutics Section, Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
authors.forename: Megha
authors.initials: M
authors.lastname: Kaushal
authors.affiliation: Laboratory of Cellular and Developmental Biology, and.
authors.forename: Ann
authors.initials: A
authors.lastname: Dean
authors.affiliation: Molecular Genomics and Therapeutics Section, Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Miller
mesh_terms: D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood / Q000188:drug therapy / Q000235:genetics; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000097:blood; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044127:Epigenesis, Genetic / Q000187:drug effects; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004920:Erythropoiesis; D005319:Fetal Hemoglobin / Q000096:biosynthesis*; D006649:Histocompatibility Antigens; D011495:Histone-Lysine N-Methyltransferase / Q000037:antagonists & inhibitors*; D006801:Humans; D066298:In Vitro Techniques; D060588:LIM Domain Proteins / Q000097:blood; D019901:Locus Control Region; D008954:Models, Biological; D011401:Promoter Regions, Genetic; D011799:Quinazolines / Q000494:pharmacology; D014157:Transcription Factors / Q000097:blood; D017086:beta-Thalassemia / Q000097:blood / Q000188:drug therapy / Q000235:genetics; D055545:gamma-Globins / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D006649:Histocompatibility Antigens; C486312:LDB1 protein, human; D060588:LIM Domain Proteins; D011799:Quinazolines; D014157:Transcription Factors; C561310:UNC 0638; D055545:gamma-Globins; D005319:Fetal Hemoglobin; C445405:EHMT2 protein, human; D011495:Histone-Lysine N-Methyltransferase