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Hematopoietic stem ell support through transcriptional coactivator TRAP220

通过转录共激活因子 TRAP220 支持造血干细胞

基本信息

批准号：
18591061
负责人：
ITO Mitsuhiro
金额：
$ 2.49万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

TRAP/Mediator complex is a multiprotein coactivator complex that mediates the signals of a variety of activators. The TRAP220/MED1 subunit is known to act as a coactivator for ligand-dependent nuclear receptor signals and some other activators such as the GATA family proteins. We have recently shown that TRAP220 plays a key role in mediating signals of nuclear receptor-dependent differentiation of not only adipocytes but white blood cells (granulocytes and monocytes). Bone marrow hematopoiesis is achieved by both hematopoietic cells and niche cells, the latter of which are comprised of osteoblasts and other type(s) of mesenchymal cells. In this study we have evaluated the role of TRAP220 in niche cells.Although the TRAP220 knockout mice am lethal before definitive hematopoiesis is dominant, the knockout mouse embryonic fibroblasts (MEF) are successfully prepared. Therefore, the MEFs, known to support hematopoietic stem/progenitor cells (HSPCs)in vitro, are used to check the ability to … More support the HSPCs. Indeed, the colony formation within the methylcellulose media was prominently decreased for bone marrow cells cultured for 6 to 8 weeks on mitomycin C-treated knockout MEFs, compared to those cultured on control MEFs. This result apparently demonstrates the role of TRAP220 in niche cells, which induce signals that mediate long-term support of HSPCs.In order to see the short-term role of TRAP220 in MEF to support bone marrow cells, we then evaluated growth and survival of bone marrow cells cultured on knockout and control MEFs. The counts of bone marrow cells on knockout MEFs were significantly decreased compared to the control ever after the 2-days culture. To know the mechanism of decreased cell numbers, we analyzed DNA synthesis and apoptosis of bone marrow cells cultured on MEFs for one or two weeks. The incorporation of BrdU into bone marrow cells cultured on knockout MEFs was prominently decreased compared to the control. Furthermore, the apoptotic cells on knockout MEFs were less than those on the control. These results indicate that the MEFs secret the signal molecules that induce proliferation stress in bone marrow cells that eventually causes apoptosis simultaneously.Thus, the TRAP220 in niche cells might mediate the signals both of the HSPCs support and the growth stress in hematopoietic progenitors. This is the first finding that the basic transctiptional coactivator complex might play a role in the hematopoietic niche. Less

TRAP/Mediator复合体是一种多蛋白共激活复合体，介导多种激活子的信号。TRAP220/MED1亚单位被认为是配体依赖的核受体信号和其他一些激活剂，如GATA家族蛋白的辅助激活剂。我们最近发现，TRAP220不仅在脂肪细胞，而且在白细胞(粒细胞和单核细胞)的核受体依赖性分化信号中起关键作用。骨髓的造血功能包括造血细胞和壁龛细胞，后者由成骨细胞和其他类型的间充质细胞(S)组成。在这项研究中，我们评估了TRAP220在壁龛细胞中的作用。尽管TRAP220基因敲除的小鼠在明确的造血占优势之前就已经死亡，但成功地制备了基因敲除的小鼠胚胎成纤维细胞(MEF)。因此，已知在体外支持造血干/祖细胞(HSPC)的MEF被用来检查…的能力更多的人支持HSPC。事实上，与培养在对照MEF上的相比，在丝裂霉素C处理的敲除MEF上培养6-8周的骨髓细胞在甲基纤维素液中的克隆形成显著减少。这一结果显然证明了TRAP220在利基细胞中的作用，它诱导了介导HSPC长期支持的信号。为了了解TRAP220在MEF中支持骨髓细胞的短期作用，我们随后评估了在基因敲除和对照MEF上培养的骨髓细胞的生长和存活。体外培养2天后，基因敲除的MEF的骨髓细胞数明显低于对照组。为了了解细胞数量减少的机制，我们分析了骨髓细胞在MEF上培养一周或两周后的DNA合成和凋亡。与对照组相比，基因敲除的MEF培养的骨髓细胞对BrdU的掺入显著减少。此外，基因敲除的MEF组的凋亡细胞数少于对照组。这些结果表明，MEF分泌了诱导骨髓细胞增殖应激的信号分子，最终导致细胞凋亡。因此，壁龛细胞中的TRAP220可能既介导了HSPC支持的信号，也介导了造血祖细胞的生长应激。这是第一次发现基本的超越辅活化子复合体可能在造血生态位中发挥作用。较少