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Blood. 2015 Oct 15;126(16):1930-9. doi: 10.1182/blood-2015-06-649087. Epub 2015 Aug 28.

EHMT1 and EHMT2 inhibition induces fetal hemoglobin expression.

Author information

1
Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA; Laboratory of Hematology, Biology and Pathology Center, Centre Hospitalier Régional Universitaire de Lille, Lille, France;
2
Harvard Medical School, Boston, MA; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA; Department of Pathology and Center for Cancer Research, Massachusetts General Hospital, Boston, MA;
3
Harvard Medical School, Boston, MA;
4
Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Boston, MA;
5
Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA;
6
Department of Pathology, Brigham and Women's Hospital, Boston, MA;
7
Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA; Department of Pathology and Center for Cancer Research, Massachusetts General Hospital, Boston, MA; Howard Hughes Medical Institute, Chevy Chase, MD;
8
Harvard Medical School, Boston, MA; Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA; and Howard Hughes Medical Institute, Boston, MA.
9
Harvard Medical School, Boston, MA; Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA; and.
10
Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA;

Abstract

Fetal hemoglobin (HbF, α2γ2) induction is a well-validated strategy for sickle cell disease (SCD) treatment. Using a small-molecule screen, we found that UNC0638, a selective inhibitor of EHMT1 and EHMT2 histone methyltransferases, induces γ-globin expression. EHMT1/2 catalyze mono- and dimethylation of lysine 9 on histone 3 (H3K9), raising the possibility that H3K9Me2, a repressive chromatin mark, plays a role in silencing γ-globin expression. In primary human adult erythroid cells, UNC0638 and EHMT1 or EHMT2 short hairpin RNA-mediated knockdown significantly increased γ-globin expression, HbF synthesis, and the percentage of cells expressing HbF. At effective concentrations, UNC0638 did not alter cell morphology, proliferation, or erythroid differentiation of primary human CD34(+) hematopoietic stem and progenitor cells in culture ex vivo. In murine erythroleukemia cells, UNC0638 and Ehmt2 CRISPR/Cas9-mediated knockout both led to a marked increase in expression of embryonic β-globin genes Hbb-εy and Hbb-βh1. In primary human adult erythroblasts, chromatin immunoprecipitation followed by sequencing analysis revealed that UNC0638 treatment leads to genome-wide depletion in H3K9Me2 and a concomitant increase in the activating mark H3K9Ac, which was especially pronounced at the γ-globin gene region. In RNA-sequencing analysis of erythroblasts, γ-globin genes were among the most significantly upregulated genes by UNC0638. Further increase in γ-globin expression in primary human adult erythroid cells was achieved by combining EHMT1/2 inhibition with the histone deacetylase inhibitor entinostat or hypomethylating agent decitabine. Our data provide genetic and pharmacologic evidence that EHMT1 and EHMT2 are epigenetic regulators involved in γ-globin repression and represent a novel therapeutic target for SCD.

PMID:
26320100
PMCID:
PMC4608240
DOI:
10.1182/blood-2015-06-649087
[Indexed for MEDLINE]
Free PMC Article

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