Division of Stem Cells and Cancer, Deutsches Krebsforschungszentrum (DKFZ), INF 280, DE-69120 Heidelberg, Germany.
Mol Cell Proteomics. 2012 Aug;11(8):286-302. doi: 10.1074/mcp.M111.016790. Epub 2012 Mar 27.
Regenerative tissues such as the skin epidermis, the intestinal mucosa or the hematopoietic system are organized in a hierarchical manner with stem cells building the top of this hierarchy. Somatic stem cells harbor the highest self-renewal activity and generate a series of multipotent progenitors which differentiate into lineage committed progenitors and subsequently mature cells. In this report, we applied an in-depth quantitative proteomic approach to analyze and compare the full proteomes of ex vivo isolated and FACS-sorted populations highly enriched for either multipotent hematopoietic stem/progenitor cells (HSPCs, Lin(neg)Sca-1(+)c-Kit(+)) or myeloid committed precursors (Lin(neg)Sca-1(-)c-Kit(+)). By employing stable isotope dimethyl labeling and high-resolution mass spectrometry, more than 5000 proteins were quantified. From biological triplicate experiments subjected to rigorous statistical evaluation, 893 proteins were found differentially expressed between multipotent and myeloid committed cells. The differential protein content in these cell populations points to a distinct structural organization of the cytoskeleton including remodeling activity. In addition, we found a marked difference in the expression of metabolic enzymes, including a clear shift of specific protein isoforms of the glycolytic pathway. Proteins involved in translation showed a collective higher expression in myeloid progenitors, indicating an increased translational activity. Strikingly, the data uncover a unique signature related to immune defense mechanisms, centering on the RIG-I and type-1 interferon response systems, which are installed in multipotent progenitors but not evident in myeloid committed cells. This suggests that specific, and so far unrecognized, mechanisms protect these immature cells before they mature. In conclusion, this study indicates that the transition of hematopoietic stem/progenitors toward myeloid commitment is accompanied by a profound change in processing of cellular resources, adding novel insights into the molecular mechanisms at the interface between multipotency and lineage commitment.
再生组织，如皮肤表皮、肠道黏膜或造血系统，是按照层级组织起来的，干细胞构成这个层级的顶端。体干细胞具有最高的自我更新活性，并产生一系列多能祖细胞，这些祖细胞分化为谱系定向祖细胞，然后再分化为成熟细胞。在本报告中，我们应用深入的定量蛋白质组学方法来分析和比较体外分离和 FACS 分选的群体的全蛋白质组，这些群体高度富集多能造血干细胞/祖细胞（HSPCs，Lin(neg)Sca-1(+)c-Kit(+)）或髓系定向前体细胞（Lin(neg)Sca-1(-)c-Kit(+)）。通过使用稳定同位素二甲基标记和高分辨率质谱，我们定量了超过 5000 种蛋白质。通过对经过严格统计学评估的三个生物学重复实验，发现 893 种蛋白质在多能和髓系定向细胞之间存在差异表达。这些细胞群体中的差异蛋白含量表明细胞骨架的结构组织存在明显差异，包括重塑活性。此外，我们发现代谢酶的表达存在明显差异，包括糖酵解途径的特定蛋白同工型的明显变化。参与翻译的蛋白质在髓系祖细胞中表现出集体更高的表达，表明翻译活性增加。引人注目的是，数据揭示了与免疫防御机制相关的独特特征，中心围绕 RIG-I 和 I 型干扰素反应系统，这些系统在多能祖细胞中安装，但在髓系定向细胞中不明显。这表明在这些不成熟的细胞成熟之前，存在特定的、迄今为止尚未被识别的机制来保护它们。总之，这项研究表明，造血干细胞/祖细胞向髓系定向的转变伴随着细胞资源处理的深刻变化，为多能性和谱系定向之间的分子机制增加了新的见解。
