GATA1 is a master transcription factor of megakaryopoiesis and erythropoiesis, and loss-of-function mutation can induce accumulation of megakaryocyte–erythroid progenitors (MEPs) in mice and humans. Accordingly, the murine MEP cell line (termed G1ME2 cells) encoding doxycycline (dox)-inducible anti-Gata1 shRNA on Hprt locus has been developed. The cells were CD41⁺CD71⁺KIT⁺, expand under dox, stem cell factor, and thrombopoietin (TPO), and terminally differentiate into erythroid cells or megakaryocytes upon removal of dox. Surprisingly, in this study, these Gata1^low murine MEPs displayed accelerated growth from around 90–100 days after cell culture, impeded megakaryocytic potential, and maintained erythropoiesis. We specified them as late G1ME2 cells and discovered that increased CD41⁻KIT⁺ population during long-term culture was the main reason for the delayed megakaryopoiesis. The CD41 expression level was partially de-repressed by PI3K/AKT inhibitors, suggesting that TPO-mediated cell survival signaling pathway might have impacted on CD41 in the late G1ME2 cells. Nevertheless, among the late cells, the CD41⁺KIT⁺ cells could still generate megakaryocytes on dox withdrawal. Taken together, G1ME2 cells could provide a good model to study molecular mechanism of hematopoiesis because of their ability to expand excessively without artificial immortalization.

GATA1是巨核细胞生成和红细胞生成的主要转录因子，功能丧失突变可诱导小鼠和人类中巨核细胞-类红细胞祖细胞（MEP）的积累。因此，鼠MEP细胞系（称为G1ME2细胞）编码多西环素（DOX）诱导型抗- GATA1的shRNA对HPRT基因座得到了发展。细胞为CD41 ⁺ CD71 ⁺ KIT ⁺，在dox，干细胞因子和血小板生成素（TPO）下扩增，并在去除dox后最终分化为类红细胞或巨核细胞。令人惊讶的是，在这项研究中，这些Gata1^低鼠MEP在细胞培养后约90-100天显示出加速的生长，阻碍了巨核细胞的潜能，并保持了红细胞生成。我们将它们指定为晚期G1ME2细胞，并发现长期培养过程中CD41 ^- KIT ⁺种群增加是导致巨核细胞生成延迟的主要原因。PI3K / AKT抑制剂可部分抑制CD41的表达水平，表明TPO介导的细胞存活信号通路可能已影响晚期G1ME2细胞的CD41。不过，在晚期细胞中，CD41 ⁺ KIT ⁺停药后，细胞仍可产生巨核细胞。两者合计，G1ME2细胞可以提供一个很好的模型来研究造血的分子机制，因为它们具有过度扩展的能力而无需人工永生化。