Lnk negatively regulates self-renewal of hematopoietic stem cells by modifying thrombopoietin-mediated signal transduction
Lnk negatively regulates self-renewal of hematopoietic stem cells by modifying thrombopoietin-mediated signal transduction
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DOI：
10.1073/pnas.0606238104
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发表时间：
2007-02-13
影响因子：
11.1
通讯作者：
Nakauchi, Hirornitsu
中科院分区：
文献类型：
--
作者：
Seita, Jun;Ema, Hideo;Nakauchi, Hirornitsu
干细胞生物学的核心任务之一是了解控制干细胞自我更新的分子机制。几种细胞因子被认为是造血干细胞（HSC）的关键调节因子，但对造血干细胞自我更新的细胞内信号知之甚少。为了解决这个问题，我们试图阐明在没有接头分子Link的情况下，造血干细胞的自我更新能力是如何增强的，因为在缺乏Link的小鼠中，造血干细胞的自我更新能力增加了10倍。我们发现，link通过改变血小板生成素（TPO）介导的信号转导，负向调节造血干细胞的自我更新。单细胞培养表明，缺乏link的造血干细胞对TPO敏感。竞争性再生表明，当这些细胞在有或没有干细胞因子的TPO存在下培养时，长期再生活性在link缺陷的hsc中增加，而在WT hsc中没有。对每个配对子细胞的单细胞移植表明，干细胞因子和TPO的组合有效地诱导了link缺陷hsc的对称自我更新分裂，而在WT hsc中则没有。新开发的单细胞免疫染色显示，TPO刺激后，link缺陷hsc中p38 MAPK失活、STAT5和Akt活化均显著增强。我们的研究结果表明，TPO信号下游正、负信号的平衡在调节造血干细胞自我更新的可能性中起作用。同样，干细胞的命运可能由多种信号转导途径的组合变化决定。
One of the central tasks of stem cell biology is to understand the molecular mechanisms that control self-renewal in stem cells. Several cytokines are implicated as crucial regulators of hematopoietic stem cells (HSCs), but little is known about intracellular signaling for HSC self-renewal. To address this issue, we attempted to clarify how self-renewal potential is enhanced in HSCs without the adaptor molecule Link, as in Lnk-deficient mice HSCs are expanded in number > 10-fold because of their increased self-renewal potential. We show that Lnk negatively regulates self-renewal of HSCs by modifying thrombopoietin (TPO)-mediated signal transduction. Single-cell cultures showed that Lnk-deficient HSCs are hypersensitive to TPO. Competitive repopulation revealed that long-term repopulating activity increases in Lnk-deficient HSCs, but not in WT HSCs, when these cells are cultured in the presence of TPO with or without stem cell factor. Single-cell transplantation of each of the paired daughter cells indicated that a combination of stem cell factor and TPO efficiently induces symmetrical self-renewal division in Lnk-deficient HSCs but not in WT HSCs. Newly developed single-cell immunostaining demonstrated significant enhancement of both p38 MAPK inactivation and STAT5 and Akt activation in Lnk-deficient HSCs after stimulation with TPO. Our results suggest that a balance in positive and negative signals downstream from the TPO signal plays a role in the regulation of the probability of self-renewal in HSCs. in general, likewise, the fate of stem cells may be determined by combinational changes in multiple signal transduction pathways.