Department of Clinical Medicine of the Faculty of Medicine of Ribeirao Preto-USP, Center for Cell Therapy and Regional Blood Center, Araraquara, São Paulo, Brazil.
Stem Cells Dev. 2010 Mar;19(3):321-32. doi: 10.1089/scd.2008.0397.
As previously shown, higher levels of NOTCH1 and increased NF-kappaB signaling is a distinctive feature of the more primitive umbilical cord blood (UCB) CD34+ hematopoietic stem cells (HSCs), as compared to bone marrow (BM). Differences between BM and UCB cell composition also account for this finding. The CD133 marker defines a more primitive cell subset among CD34+ HSC with a proposed hemangioblast potential. To further evaluate the molecular basis related to the more primitive characteristics of UCB and CD133+ HSC, immunomagnetically purified human CD34+ and CD133+ cells from BM and UCB were used on gene expression microarrays studies. UCB CD34+ cells contained a significantly higher proportion of CD133+ cells than BM (70% and 40%, respectively). Cluster analysis showed that BM CD133+ cells grouped with the UCB cells (CD133+ and CD34+) rather than to BM CD34+ cells. Compared with CD34+ cells, CD133+ had a higher expression of many transcription factors (TFs). Promoter analysis on all these TF genes revealed a significantly higher frequency (than expected by chance) of NF-kappaB-binding sites (BS), including potentially novel NF-kappaB targets such as RUNX1, GATA3, and USF1. Selected transcripts of TF related to primitive hematopoiesis and self-renewal, such as RUNX1, GATA3, USF1, TAL1, HOXA9, HOXB4, NOTCH1, RELB, and NFKB2 were evaluated by real-time PCR and were all significantly positively correlated. Taken together, our data indicate the existence of an interconnected transcriptional network characterized by higher levels of NOTCH1, NF-kappaB, and other important TFs on more primitive HSC sets.
如前所述，与骨髓（BM）相比，更高水平的 NOTCH1 和增加的 NF-kappaB 信号是更原始的脐带血（UCB）CD34+造血干细胞（HSCs）的一个显著特征。BM 和 UCB 细胞组成之间的差异也解释了这一发现。CD133 标志物定义了 CD34+HSC 中更原始的细胞亚群，具有拟血管母细胞潜能。为了进一步评估与 UCB 和 CD133+HSC 的更原始特征相关的分子基础，使用免疫磁珠从 BM 和 UCB 纯化人 CD34+和 CD133+细胞进行基因表达微阵列研究。UCB CD34+细胞中 CD133+细胞的比例明显高于 BM（分别为 70%和 40%）。聚类分析显示，BM CD133+细胞与 UCB 细胞（CD133+和 CD34+）聚类，而不是与 BM CD34+细胞聚类。与 CD34+细胞相比，CD133+细胞表达许多转录因子（TF）的水平更高。对所有这些 TF 基因的启动子分析显示，NF-kappaB 结合位点（BS）的频率（高于预期的随机概率）显著更高，包括潜在的新的 NF-kappaB 靶标，如 RUNX1、GATA3 和 USF1。与原始造血和自我更新相关的 TF 转录本，如 RUNX1、GATA3、USF1、TAL1、HOXA9、HOXB4、NOTCH1、RELB 和 NFKB2，通过实时 PCR 进行评估，均呈显著正相关。总之，我们的数据表明，在更原始的 HSC 中存在一个相互关联的转录网络，其特征是 NOTCH1、NF-kappaB 和其他重要 TF 的水平更高。
