Komatsu N, Kunitama M, Yamada M, Hagiwara T, Kato T, Miyazaki H, Eguchi M, Yamamoto M, Miura Y
Division of Hematology, Department of Medicine, Jichi Medical School, Tochigi, Japan.
Blood. 1996 Jun 1;87(11):4552-60.
UT-7 is a human megakaryoblastic leukemia cell line with absolute dependence on interleukin-3, granulocyte-macrophage colony-stimulating factor, or erythropoietin (EPO) for growth and survival. We investigated the effect of thrombopoietin (TPO), the ligand for the receptor encoded by c-mpl proto-oncogene, on the proliferation and differentiation of UT-7 and its sublines. We found that UT-7/GM, which is a subline of UT-7, but neither UT-7 nor UT-7/EPO, can proliferate in response to TPO. The subline, UT-7/TPO, was established from UT-7/GM by culture at lower concentrations of TPO. UT-7/TPO cells had morphologically mature megakaryocytic characteristics such as developed demarcation membrane in the cytoplasm and multinucleated appearance. This was also confirmed by the high expression of platelet factor-4 and glycoprotein IIb at the mRNA levels and by the high level of DNA content. UT-7/TPO can be maintained by TPO alone, with a doubling time of 24 hours in log growth phase. In the absence of TPO, the majority of the cells died within a few days. Thus, UT-7/TPO has an absolute dependence on TPO for growth and survival and has mature megakaryocytic features. The mRNA for c-mpl was detected in UT-7/TPO and, to a lesser degree, in UT-7/GM. The mRNA level of NF- E2 p45, reported to be an erythroid-specific transcription factor, was upregulated in UT-7/TPO, whereas it was down-regulated in the erythroid subline, UT-7/EPO. There were no significant differences in GATA-1 and GATA-2 mRNA levels among UT-7 and its sublines. Not only EPO but also TPO induced the tyrosine phosphorylation of JAK2 tyrosine kinase and STAT5-related protein. These findings indicate that UT-7/TPO would be a useful model with which to analyze the gene regulation of megakaryocytic maturation-associated proteins and to study the specific actions of TPO.
UT-7是一种人巨核细胞白血病细胞系，其生长和存活绝对依赖于白细胞介素-3、粒细胞-巨噬细胞集落刺激因子或促红细胞生成素（EPO）。我们研究了血小板生成素（TPO）（c-mpl原癌基因编码的受体的配体）对UT-7及其亚系增殖和分化的影响。我们发现，UT-7的一个亚系UT-7/GM能够对TPO产生增殖反应，但UT-7和UT-7/EPO均无此反应。UT-7/TPO亚系是通过在较低浓度的TPO中培养从UT-7/GM建立的。UT-7/TPO细胞具有形态学上成熟的巨核细胞特征，如细胞质中发达的分界膜和多核外观。这也通过血小板因子-4和糖蛋白IIb在mRNA水平的高表达以及高DNA含量得到证实。UT-7/TPO仅在TPO存在下就能维持生长，对数生长期的倍增时间为24小时。在没有TPO的情况下，大多数细胞在几天内死亡。因此，UT-7/TPO的生长和存活绝对依赖于TPO，并具有成熟的巨核细胞特征。在UT-7/TPO中检测到了c-mpl的mRNA，在UT-7/GM中也有较低程度的表达。据报道，作为一种红系特异性转录因子的NF-E2 p45的mRNA水平在UT-7/TPO中上调，而在红系亚系UT-7/EPO中下调。UT-7及其亚系之间GATA-1和GATA-2的mRNA水平没有显著差异。不仅EPO，而且TPO都能诱导JAK2酪氨酸激酶和STAT5相关蛋白的酪氨酸磷酸化。这些发现表明，UT-7/TPO将是一个有用的模型，可用于分析巨核细胞成熟相关蛋白的基因调控以及研究TPO的具体作用。
