Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, MA 01655, USA.
Hum Mol Genet. 2010 Mar 15;19(6):1048-57. doi: 10.1093/hmg/ddp568. Epub 2009 Dec 24.
Runx1 is a key hematopoietic transcription factor required for definitive hematopoiesis and is a frequent target of leukemia-related chromosomal translocations. The resulting fusion proteins, while retaining DNA binding activity, display loss of subnuclear targeting and associated transactivation functions encoded by the C-terminus of the protein. To define the precise contribution of the Runx1 C-terminus in development and leukemia, we created a knock-in mouse with a C-terminal truncation by introducing a single nucleic acid substitution in the native Runx1 locus. This mutation (Runx1(Q307X)) models genetic lesions observed in patients with leukemia and myeloproliferative disorders. The Runx1(Q307X) homozygous mouse exhibits embryonic lethality at E12.5 due to central nervous system hemorrhages and a complete lack of hematopoietic stem cell function. While able to bind DNA, Runx1(Q307X) is unable to activate target genes, resulting in deregulation of various hematopoietic markers. Thus, we demonstrate that the subnuclear targeting and transcriptional regulatory activities of the Runx1 C-terminus are critical for hematopoietic development. We propose that compromising the C-terminal functions of Runx1 is a common mechanism for the pathological consequences of a variety of somatic mutations and Runx1-related leukemic fusion proteins observed in human patients.
Runx1 是一种关键的造血转录因子，对于确定的造血作用是必需的，并且是白血病相关染色体易位的常见靶标。由此产生的融合蛋白虽然保留了 DNA 结合活性，但显示出亚核靶向和由蛋白质 C 末端编码的相关反式激活功能的丧失。为了确定 Runx1 C 末端在发育和白血病中的精确贡献，我们通过在天然 Runx1 基因座中引入单个核酸取代，在敲入小鼠中创建了 C 末端截断。这种突变（Runx1(Q307X)）模拟了在白血病和骨髓增生性疾病患者中观察到的遗传病变。Runx1(Q307X) 纯合子小鼠由于中枢神经系统出血和完全缺乏造血干细胞功能，在 E12.5 时表现出胚胎致死性。虽然能够结合 DNA，但 Runx1(Q307X) 无法激活靶基因，导致各种造血标记物的失调。因此，我们证明了 Runx1 C 末端的亚核靶向和转录调节活性对于造血发育至关重要。我们提出，破坏 Runx1 的 C 末端功能是人类患者中观察到的各种体细胞突变和 Runx1 相关白血病融合蛋白的病理后果的共同机制。
