Cell-cycle-dependent oscillation of GATA2 expression in hematopoietic cells
Cell-cycle-dependent oscillation of GATA2 expression in hematopoietic cells
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DOI：
10.1182/blood-2006-08-044149
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发表时间：
2007-05-15
期刊：
影响因子：
20.3
通讯作者：
Minegishi, Naoko
中科院分区：
文献类型：
--
作者：
Koga, Shinichiro;Yamaguchi, Nobuhiro;Minegishi, Naoko
造血干细胞的体外操作是移植治疗和再生医学中的关键问题，因此需要新的方法来实现造血干细胞的扩增和自我更新。GATA2是一种控制HSCs池大小的转录因子。值得注意的是，持续过表达GATA2并不能诱导HSC增殖。在这篇报道中，我们证明了GATA2在白血病和正常造血细胞中的表达在细胞周期中振荡，在S期高表达，而在G(1)/S和M期低表达。GATA2与靶基因BclX的结合也随着GATA2的表达而振荡。使用绿色荧光蛋白(GFP)-GATA2融合蛋白，我们展示了依赖于蛋白酶体的GATA2降解的细胞周期特异性活性。免疫沉淀/免疫印迹分析表明，GATA2在细胞周期蛋白依赖性蛋白依赖性蛋白激酶的共同基序S/T0P+1处被磷酸化，并与CDK2/Cyclin A2-、CDK2/Cyclin A2-和CDK4/Cyclin D1-磷酸化的GATA2相互作用。磷酸化基序中的突变体显示GFP-GATA2结构域融合蛋白的表达谱发生了变化。这些结果表明，CDK/Cyclin系统对GATA2的磷酸化是细胞周期依赖性调节GATA2表达的原因，提示GATA2表达的“开-关”反应可能控制造血细胞的增殖和存活。
In vitro manipulation of hematopoietic stem cells (HSCs) is a key issue in both transplantation therapy and regenerative medicine, and thus new methods are required to achieve HSC expansion with self-renewal. GATA2 is a transcription factor controlling pool size of HSCs. Of interest, continuous overexpression of GATA2 does not induce HSC proliferation. In this report, we demonstrate that GATA2 expression, in leukemic and normal hematopoietic cells, oscillates during the cell cycle, such that expression is high in S phase but low in G(1)/S and M phase. GATA2 binding to target Bcl-X gene also oscillates in accordance with GATA2 expression. Using a green fluorescent protein (GFP)-GATA2 fusion protein, we demonstrate cell-cycle-specific activity of proteasome-dependent degradation of GATA2. Immunoprecipitation/immunoblotting analysis demonstrated phosphorylation of GATA2 at cyclin-dependent kinase (Cdk)-consensus motifs, S/T0P+1, and interaction of GATA2 with Cdk2/ cyclin A2-, Cdk2/cyclin A2-, and Cdk4/cyclin D1-phosphorylated GATA2 in vitro. Mutants in phosphorylation motifs exhibited altered expression profiles of GFP-GATA2 domain fusion proteins. These results indicate that GATA2 phosphorylation by Cdk/cyclin systems is responsible for the cell-cycle-dependent regulation of GATA2 expression, and suggest the possibility that a cell-cycle-specific "on-off" response of GATA2 expression may control hematopoietic-cell proliferation and survival.