Identification of a Novel Enhancer/Chromatin Opening Element Associated with High-Level γ -Globin Gene Expression

作者：Yong Shen, Maclean Bassett, Aishwarya Gurumurthy, Rukiye Nar, Isaac J. Knudson, Cameron R. Guy, Álex Pérez, Russell Mellen, Masatoshi Ikeda, Mir Ahamed Hossain, Suming Huang, Kazuhiko Igarashi, Jörg Bungert · 发表于：Molecular and Cellular Biology · 年份：2018 · DOI：10.1128/mcb.00197-18 · 被引用次数：10 · 研究领域：Genomics and Chromatin Dynamics、Epigenetics and DNA Methylation、Cancer-related gene regulation

The organization of the five β-type globin genes on chromosome 11 reflects the timing of expression during erythroid cell development, with the embryonic ε-globin gene being located at the 5′ end, followed by the two fetal γ-globin genes, and with the adult β- and δ-globin genes being located at the 3′ end. Here, we functionally characterized a DNase I-hypersensitive site (HS) located 4 kb upstream of the Gγ-globin gene (HBG-4kb HS). This site is occupied by transcription factors USF1, USF2, EGR1, MafK, and NF-E2 in the human erythroleukemia cell line K562 and exhibits histone modifications typical for enhancers. We generated a synthetic zinc finger (ZF) DNA-binding domain targeting the HBG-4kb HS (HBG-4kb ZF). The HBG-4kb ZF interacted with the target site in vitro and in the context of cells with a high affinity and specificity. Direct delivery of the HBG-4kb ZF to K562 and primary human erythroid cells caused a reduction in γ-globin gene expression which was associated with decreased binding of transcription factors and active histone marks at and downstream of the HS. The data demonstrate that the HBG-4kb HS is important for fetal globin production and suggest that it may act by opening chromatin in a directional manner.