EAF1和EAF2是与十一九赖氨酸富含白血病(ELL)相关的因子，可组装成超级伸长复合物(AFF1/4、AF9/ENL、ELL和P-TEFb)参与RNA聚合酶II调节各种生物过程，包括白血病和胚胎发育。然而，EAF1/2在血液系统相关的胚胎缺氧耐受性中的作用是否存在以及如何作用还不清楚。在这里，我们揭示了删除EAF1/2(eaf1-/-和eaf2-/-)会导致斑马鱼的缺氧耐受性降低，在造血过程中导致红细胞生成减少。同时，在含有eaf1-/-和eaf2-/-基因突变的斑马鱼中，红细胞生成中关键转录调节因子scl、lmo2和gata1a的表达均显著降低，14个hpf时gata1a下调，而scl和lmo2上调。在机械上，eaf1-/-和eaf2-/-突变体在组蛋白修饰组中呈现明显变化，且在gata1a启动子中修饰的组蛋白H3K27me3的结合富集显著增加，而不是在scl和lmo2启动子中。此外，在红细胞生成过程中，eaf1-/-和eaf2-/-突变体表现出经典WNT/β-catenin信号的动态表达，24个hpf时p-β-Catenin水平显著降低，并且在scl和lmo2启动子处的WNT转录因子TCF4的结合富集也显著降低。这些发现展示了Eaf1/2在斑马鱼红细胞生成中的重要作用，并可能为贫血和相关疾病的再生医学以及鱼类经济或生产特性(如生长、疾病抗性、缺氧耐受性等)的分子基础提供一些线索。© 2023.作者(们)

EAF1 and EAF2, the eleven-nineteen lysine-rich leukemia (ELL)-associated factors which can assemble to the super elongation complex (AFF1/4, AF9/ENL, ELL, and P-TEFb), are reported to participate in RNA polymerase II to actively regulate a variety of biological processes, including leukemia and embryogenesis, but whether and how EAF1/2 function in hematopoietic system related hypoxia tolerance during embryogenesis remains unclear. Here, we unveiled that deletion of EAF1/2 (eaf1-/- and eaf2-/-) caused reduction in hypoxia tolerance in zebrafish, leading to reduced erythropoiesis during hematopoietic processes. Meanwhile, eaf1-/- and eaf2-/- mutants showed significant reduction in the expression of key transcriptional regulators scl, lmo2, and gata1a in erythropoiesis at both 24 h post fertilization (hpf) and 72 hpf, with gata1a downregulated while scl and lmo2 upregulated at 14 hpf. Mechanistically, eaf1-/- and eaf2-/- mutants exhibited significant changes in the expression of epigenetic modified histones, with a significant increase in the binding enrichment of modified histone H3K27me3 in gata1a promoter rather than scl and lmo2 promoters. Additionally, eaf1-/- and eaf2-/- mutants exhibited a dynamic expression of canonical WNT/β-catenin signaling during erythropoiesis, with significant reduction in p-β-Catenin level and in the binding enrichment of both scl and lmo2 promoters with the WNT transcriptional factor TCF4 at 24 hpf. These findings demonstrate an important role of Eaf1/2 in erythropoiesis in zebrafish and may have shed some light on regeneration medicine for anemia and related diseases and on molecular basis for fish economic or productive traits, such as growth, disease resistance, hypoxia tolerance, and so on.© 2023. The Author(s).