Chromatin and Gene Expression Section, Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Differentiation. 2012 Nov;84(4):330-43. doi: 10.1016/j.diff.2012.07.006. Epub 2012 Aug 18.
The heterogeneous nature of stem cells is an important issue in both research and therapeutic use in terms of directing cell lineage differentiation pathways, as well as self-renewal properties. Using flow cytometry we have identified two distinct subpopulations by size, large and small, within cultures of human embryonic stem (hES) cell lines. These two cell populations respond differentially to retinoic acid (RA) differentiation and several endocrine disruptor compounds (EDC). The large cell population responds to retinoic acid differentiation with greater than a 50% reduction in cell number and loss of Oct-4 expression, whereas the number of the small cell population does not change and Oct-4 protein expression is maintained. In addition, four estrogenic compounds altered SSEA-3 expression differentially between the two cell subpopulations changing their ratios relative to each other. Both populations express stem cell markers Oct-4, Nanog, Tra-1-60, Tra-1-80 and SSEA-4, but express low levels of differentiation markers common to the three germ layers. Cloning studies indicate that both populations can revive the parental population. Furthermore, whole genome microarray identified approximately 400 genes with significantly different expression between the two populations (p<0.01). We propose the differential response to RA in these populations is due to differential gene expression of Notch signaling members, CoupTF1 and CoupTF2, chromatin remodeling and histone modifying genes that render the small population resistant to RA differentiation. The findings that hES cells exist as heterogeneous populations with distinct responses to differentiation signals and environmental stimuli will be relevant for their use for drug discovery and disease therapy.
干细胞的异质性是一个重要的问题，无论是在研究还是治疗应用中，都涉及到指导细胞谱系分化途径以及自我更新特性。我们使用流式细胞术根据大小大小，在人胚胎干细胞（hES）细胞系的培养物中鉴定出两个不同的亚群，即大细胞和小细胞。这两个细胞群体对维甲酸（RA）分化和几种内分泌干扰化合物（EDC）的反应不同。大细胞群体对维甲酸分化的反应是细胞数量减少超过 50%，Oct-4 表达丧失，而小细胞群体的数量不变，Oct-4 蛋白表达保持不变。此外，四种雌激素化合物改变了两个细胞亚群之间的 SSEA-3 表达的差异，改变了它们彼此之间的比例。两个群体都表达干细胞标志物 Oct-4、Nanog、Tra-1-60、Tra-1-80 和 SSEA-4，但表达三个胚层共有的低水平分化标志物。克隆研究表明，两个群体都可以恢复原始群体。此外，全基因组微阵列鉴定出两个群体之间存在约 400 个基因的表达存在显著差异（p<0.01）。我们提出，这些群体对 RA 的不同反应是由于 Notch 信号成员、CoupTF1 和 CoupTF2、染色质重塑和组蛋白修饰基因的差异表达所致，这些基因使小群体对 RA 分化具有抗性。这些发现表明，hES 细胞存在异质性群体，对分化信号和环境刺激有不同的反应，这将与其在药物发现和疾病治疗中的应用相关。
