EHMT1 and EHMT2 inhibition induces fetal hemoglobin expression.

Blood
Authors
Keywords
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.

Year of Publication
2015
Journal
Blood
Volume
126
Issue
16
Pages
1930-9
Date Published
2015 Oct 15
ISSN
1528-0020
URL
DOI
10.1182/blood-2015-06-649087
PubMed ID
26320100
PubMed Central ID
PMC4608240
Links
Grant list
R01 HL032259 / HL / NHLBI NIH HHS / United States
U01 HL117720 / HL / NHLBI NIH HHS / United States
P30 DK056465 / DK / NIDDK NIH HHS / United States
1U01HL117720 / HL / NHLBI NIH HHS / United States
DK56465 / DK / NIDDK NIH HHS / United States
F30DK103359-01A1 / DK / NIDDK NIH HHS / United States
F30 DK103359 / DK / NIDDK NIH HHS / United States