Transcription Factors KLF1 and KLF2 Positively Regulate Embryonic and Fetal β-Globin Genes through Direct Promoter Binding
Transcription Factors KLF1 and KLF2 Positively Regulate Embryonic and Fetal β-Globin Genes through Direct Promoter Binding
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DOI：
10.1074/jbc.m111.247536
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发表时间：
2011-07-15
影响因子：
4.8
通讯作者：
Lloyd, Joyce A.
中科院分区：
文献类型：
--
作者：
Alhashem, Yousef N.;Vinjamur, Divya S.;Lloyd, Joyce A.
Kruppel样因子（KLF）控制细胞分化和胚胎发育。KLF 1（红细胞Kruppel样因子）在胚胎和成人红细胞生成中起重要作用。KLF 2是小鼠和人类胚胎β-珠蛋白基因的正调控因子。KLF 1和KLF 2具有高度同源的锌指DNA结合结构域。它们在胚胎红细胞生成中具有重叠的作用，如使用单和双KO小鼠模型所证明的。KLF 1或KLF 2基因的切除会导致胚胎死亡，但双KO胚胎比单KO胚胎更贫血且死亡更早。在这项工作中，使用了双重人β-珠蛋白基因座转基因和KLF敲除小鼠模型。结果表明，人类胚胎和胎儿γ-珠蛋白基因在胚胎中受到KLF 1和KLF 2的正调控。条件性KO小鼠实验表明，KLF 2对胚胎珠蛋白基因调控的影响至少部分是红系细胞自主的。KLF 1和KLF 2直接与人β-和γ-珠蛋白基因、小鼠胚胎Ey-和β h1-珠蛋白基因的启动子结合，还与β-珠蛋白基因座控制区结合，如小鼠胚胎血细胞ChIP试验所示。H3 K9 Ac和H3 K4 me 3标记分别指示开放的染色质和活跃的转录。这些标记在KLF 1（-/-）胚胎的Ey-、β h1-、β-和γ-珠蛋白基因和基因座控制区减少，与基因表达减少相关。因此，KLF 1和KLF 2通过直接启动子结合正向调节胚胎和胎儿β-珠蛋白基因。KLF 1是小鼠胚胎中β-珠蛋白基因座中正常组蛋白修饰所必需的。
Kruppel-like factors (KLFs) control cell differentiation and embryonic development. KLF1 (erythroid Kruppel-like factor) plays essential roles in embryonic and adult erythropoiesis. KLF2 is a positive regulator of the mouse and human embryonic beta-globin genes. KLF1 and KLF2 have highly homologous zinc finger DNA-binding domains. They have overlapping roles in embryonic erythropoiesis, as demonstrated using single and double KO mouse models. Ablation of the KLF1 or KLF2 gene causes embryonic lethality, but double KO embryos are more anemic and die sooner than either single KO. In this work, a dual human beta-globin locus transgenic and KLF knockout mouse model was used. The results demonstrate that the human epsilon-(embryonic) and gamma-globin (fetal) genes are positively regulated by KLF1 and KLF2 in embryos. Conditional KO mouse experiments indicate that the effect of KLF2 on embryonic globin gene regulation is at least partly erythroid cell-autonomous. KLF1 and KLF2 bind directly to the promoters of the human epsilon- and gamma-globin genes, the mouse embryonic Ey- and beta h1-globin genes, and also to the beta-globin locus control region, as demonstrated by ChIP assays with mouse embryonic blood cells. H3K9Ac and H3K4me3 marks indicate open chromatin and active transcription, respectively. These marks are diminished at the Ey-, beta h1-, epsilon- and gamma-globin genes and locus control region in KLF1(-/-) embryos, correlating with reduced gene expression. Therefore, KLF1 and KLF2 positively regulate the embryonic and fetal beta-globin genes through direct promoter binding. KLF1 is required for normal histone modifications in the beta-globin locus in mouse embryos.