NRF2 is the master regulator for the cellular oxidative stress response and regulates γ-globin gene expression in human erythroid progenitors and sickle cell disease mice. To explore NRF2 function, we established a human β-globin locus yeast artificial chromosome transgenic/NRF2 knockout (β-YAC/NRF2^−/−) mouse model. NRF2 loss reduced γ-globin gene expression during erythropoiesis and abolished the ability of dimethyl fumarate, an NRF2 activator, to enhance γ-globin transcription. We observed decreased H3K4Me1 and H3K4Me3 chromatin marks and association of TATA-binding protein and RNA polymerase II at the β-locus control region (LCR) and γ-globin gene promoters in β-YAC/NRF2^−/− mice. As a result, long-range chromatin interaction between the LCR DNase I hypersensitive sites and γ-globin gene was decreased, while interaction with the β-globin was not affected. Further, NRF2 loss silenced the expression of DNA methylcytosine dioxygenases TET1, TET2, and TET3 and inhibited γ-globin gene DNA hydroxymethylation. Subsequently, protein-protein interaction between NRF2 and TET3 was demonstrated. These data support the ability of NRF2 to mediate γ-globin gene regulation through epigenetic DNA and histone modifications.

Impact statement

Sickle cell disease is an inherited hemoglobin disorder that affects over 100,000 people in the United States causing high morbidity and early mortality. Although new treatments were recently approved by the FDA, only one drug Hydroxyurea induces fetal hemoglobin expression to inhibit sickle hemoglobin polymerization in red blood cells. Our laboratory previously demonstrated the ability of the NRF2 activator, dimethyl fumarate to induce fetal hemoglobin in the sickle cell mouse model. In this study, we investigated molecular mechanisms of γ-globin gene activation by NRF2. We observed the ability of NRF2 to modulate chromatin structure in the human β-like globin gene locus of β-YAC transgenic mice during development. Furthermore, an NRF2/TET3 interaction regulates γ-globin gene DNA methylation. These findings provide potential new molecular targets for small molecule drug developed for treating sickle cell disease.

中文翻译：

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NRF2 在 β-YAC 转基因小鼠模型中通过表观遗传修饰介导 γ-珠蛋白基因调控。

NRF2 是细胞氧化应激反应的主要调节因子，可调节人红系祖细胞和镰状细胞病小鼠的 γ-珠蛋白基因表达。为了探索 NRF2 的功能，我们建立了人类 β-珠蛋白基因座酵母人工染色体转基因/NRF2 敲除 (β-YAC/NRF2 ^-/- ) 小鼠模型。NRF2 缺失降低了红细胞生成过程中的 γ-珠蛋白基因表达，并消除了 NRF2 激活剂富马酸二甲酯增强 γ-珠蛋白转录的能力。我们观察到 H3K4Me1 和 H3K4Me3 染色质标记减少，以及 β-基因座控制区 (LCR) 和 β-YAC/NRF2 中 γ-珠蛋白基因启动子的 TATA 结合蛋白和 RNA 聚合酶 II 的关联^-/-老鼠。结果，LCR DNase I 过敏位点与 γ-珠蛋白基因之间的远程染色质相互作用减少，而与 β-珠蛋白的相互作用不受影响。此外，NRF2 缺失沉默了 DNA 甲基胞嘧啶双加氧酶 TET1、TET2 和 TET3 的表达，并抑制了 γ-珠蛋白基因 DNA 羟甲基化。随后，证明了 NRF2 和 TET3 之间的蛋白质-蛋白质相互作用。这些数据支持 NRF2 通过表观遗传 DNA 和组蛋白修饰介导 γ-珠蛋白基因调控的能力。

影响声明

镰状细胞病是一种遗传性血红蛋白疾病，在美国影响超过 100,000 人，导致高发病率和早期死亡率。尽管 FDA 最近批准了新的治疗方法，但只有一种药物羟基脲可诱导胎儿血红蛋白表达，从而抑制红细胞中镰状血红蛋白的聚合。我们的实验室之前证明了 NRF2 激活剂富马酸二甲酯在镰状细胞小鼠模型中诱导胎儿血红蛋白的能力。在这项研究中，我们研究了 NRF2 激活 γ-珠蛋白基因的分子机制。我们观察到 NRF2 在发育过程中调节 β-YAC 转基因小鼠的人 β 样珠蛋白基因座染色质结构的能力。此外，NRF2/TET3 相互作用调节 γ-珠蛋白基因 DNA 甲基化。