Guan Fiona H X, Bailey Charles G, Metierre Cynthia, O'Young Patrick, Gao Dadi, Khoo Teh Liane, Holst Jeff, Rasko John E J
Gene and Stem Cell Therapy Program, Centenary Institute, University of Sydney, Camperdown, NSW, 2050, Australia.
Sydney Medical School, University of Sydney, Camperdown, NSW, 2006, Australia.
J Hematol Oncol. 2017 Mar 28;10(1):75. doi: 10.1186/s13045-017-0446-7.
ELF2 (E74-like factor 2) also known as NERF (new Ets-related factor), a member of the Ets family of transcription factors, regulates genes important in B and T cell development, cell cycle progression, and angiogenesis. Conserved ELF2 isoforms, ELF2A, and ELF2B, arising from alternative promoter usage can exert opposing effects on target gene expression. ELF2A activates, whilst ELF2B represses, gene expression, and the balance of expression between these isoforms may be important in maintaining normal cellular function.
We compared the function of ELF2 isoforms ELF2A and ELF2B with other ELF subfamily proteins ELF1 and ELF4 in primary and cancer cell lines using proliferation, colony-forming, cell cycle, and apoptosis assays. We further examined the role of ELF2 isoforms in haemopoietic development using a Rag1 murine bone marrow reconstitution model.
ELF2B overexpression significantly reduced cell proliferation and clonogenic capacity, minimally disrupted cell cycle kinetics, and induced apoptosis. In contrast, ELF2A overexpression only marginally reduced clonogenic capacity with little effect on proliferation, cell cycle progression, or apoptosis. Deletion of the N-terminal 19 amino acids unique to ELF2B abrogated the antiproliferative and proapoptotic functions of ELF2B thereby confirming its crucial role. Mice expressing Elf2a or Elf2b in haemopoietic cells variously displayed perturbations in the pre-B cell stage and multiple stages of T cell development. Mature B cells, T cells, and myeloid cells in steady state were unaffected, suggesting that the main role of ELF2 is restricted to the early development of B and T cells and that compensatory mechanisms exist. No differences in B and T cell development were observed between ELF2 isoforms.
We conclude that ELF2 isoforms are important regulators of cellular proliferation, cell cycle progression, and apoptosis. In respect to this, ELF2B acts in a dominant negative fashion compared to ELF2A and as a putative tumour suppressor gene. Given that these cellular processes are critical during haemopoiesis, we propose that the regulatory interplay between ELF2 isoforms contributes substantially to early B and T cell development.
ELF2（E74样因子2）也被称为NERF（新的Ets相关因子），是转录因子Ets家族的成员，可调节在B和T细胞发育、细胞周期进程及血管生成中起重要作用的基因。由于使用了不同的启动子，保守的ELF2异构体ELF2A和ELF2B可对靶基因表达产生相反的影响。ELF2A激活基因表达，而ELF2B抑制基因表达，这些异构体之间的表达平衡对于维持正常细胞功能可能很重要。
我们使用增殖、集落形成、细胞周期和凋亡检测方法，比较了ELF2异构体ELF2A和ELF2B与其他ELF亚家族蛋白ELF1和ELF4在原代细胞系和癌细胞系中的功能。我们还使用Rag1小鼠骨髓重建模型进一步研究了ELF2异构体在造血发育中的作用。
ELF2B的过表达显著降低了细胞增殖和克隆形成能力，对细胞周期动力学的干扰最小，并诱导了凋亡。相比之下，ELF2A的过表达仅略微降低了克隆形成能力，对增殖、细胞周期进程或凋亡几乎没有影响。删除ELF2B特有的N端19个氨基酸消除了ELF2B的抗增殖和促凋亡功能，从而证实了其关键作用。在造血细胞中表达Elf2a或Elf2b的小鼠在pre-B细胞阶段和T细胞发育的多个阶段出现了不同程度的扰动。稳态下的成熟B细胞、T细胞和髓细胞未受影响，这表明ELF2的主要作用仅限于B和T细胞的早期发育，并且存在补偿机制。在ELF2异构体之间未观察到B和T细胞发育的差异。
我们得出结论，ELF2异构体是细胞增殖、细胞周期进程和凋亡的重要调节因子。就此而言，与ELF2A相比，ELF2B以显性负性方式起作用，并且作为一个假定的肿瘤抑制基因。鉴于这些细胞过程在造血过程中至关重要，我们提出ELF2异构体之间的调节相互作用对早期B和T细胞发育有很大贡献。
