Tao Wen, Wang Mu, Voss Emily D, Cocklin Ross R, Smith Jaime A, Cooper Scott H, Broxmeyer Hal E
Department of Microbiology and Immunology, Indiana University School of Medicine, 950 West Walnut Street, Indianapolis, Indiana 46202, USA.
Stem Cells. 2004;22(6):1003-14. doi: 10.1634/stemcells.22-6-1003.
Human CD34(+) cells, highly enriched for hematopoietic stem and progenitors, and CD15(+) cells, more terminally differentiated myeloid cells in blood, represent distinct maturation/differentiation stages. A proteomic approach was used to identify proteins differentially present in these two populations from human cord blood. Cytosolic proteins were extracted and subjected to two-dimensional gel electrophoresis followed by mass spectrometry. On average, 460 protein spots on each gel were detected; 112 and 15 proteins, respectively, were found to be differentially expressed or post-translationally modified in CD34(+) and CD15(+) cells. This suggests that CD34(+) cells have a relatively larger proteome than mature CD15(+) myeloid cells and production of many stem/progenitor cell-associated proteins ceases or is dramatically down-regulated as the CD34(+) cells undergo differentiation. Of approximately 140 protein spots, 47 different proteins were positively identified by mass spectrometry and database search; these proteins belong to several functional categories, including cell signaling, transcription factors, cytoskeletal proteins, metabolism, protein folding, and vesicle trafficking. Multiple heat shock proteins and chaperones, as well as proteins important for intracellular trafficking, were predominantly present in CD34(+) cells. Most of the identified proteins in CD34(+) cells are expressed in germ cell tumors, as well as in embryonal carcinoma and neuroblastoma. Approximately eight novel proteins, whose functions are unknown, were identified. This study presents, for the first time, global cellular protein expression patterns in human CD34(+) and CD15(+) cells, which should help to better understand intracellular processes involved in myeloid differentiation and add insight into the functional capabilities of these distinct cell types.
人CD34(+)细胞高度富集造血干细胞和祖细胞，而CD15(+)细胞是血液中终末分化程度更高的髓样细胞，它们代表不同的成熟/分化阶段。采用蛋白质组学方法鉴定人脐带血中这两种细胞群中差异存在的蛋白质。提取胞质蛋白，进行二维凝胶电泳，随后进行质谱分析。每张凝胶平均检测到460个蛋白点；分别发现112个和15个蛋白在CD34(+)和CD15(+)细胞中差异表达或发生翻译后修饰。这表明CD34(+)细胞的蛋白质组相对比成熟的CD15(+)髓样细胞大，并且随着CD34(+)细胞分化，许多与干细胞/祖细胞相关的蛋白质的产生停止或显著下调。在大约140个蛋白点中，通过质谱分析和数据库搜索成功鉴定出47种不同的蛋白质；这些蛋白质属于几个功能类别，包括细胞信号传导、转录因子、细胞骨架蛋白、代谢、蛋白质折叠和囊泡运输。多种热休克蛋白和伴侣蛋白以及对细胞内运输重要的蛋白质主要存在于CD34(+)细胞中。CD34(+)细胞中鉴定出的大多数蛋白质在生殖细胞肿瘤以及胚胎癌和神经母细胞瘤中也有表达。鉴定出大约8种功能未知的新蛋白质。本研究首次展示了人CD34(+)和CD15(+)细胞中的整体细胞蛋白质表达模式，这将有助于更好地理解髓样分化过程中涉及的细胞内过程，并深入了解这些不同细胞类型的功能能力。
