Regulation of Hypoxia-Inducible Factors in Pluripotent Cancer Cells.

缺氧诱导因子（HIF）在细胞自我更新和维持中的直接作用 干细胞和多能细胞的研究得到了一些观察结果的支持。首先，HIF是一种重要的 参与Notch靶转录激活的Notch信号通路的配偶体 维持神经和肌源性干细胞处于未分化状态所必需的基因。 第二，HIF-2转录激活Oct-4基因表达，从而有助于 造血干细胞分化缺陷和大胚胎干细胞来源的 以未分化细胞数量增加为特征的肿瘤。HIF的作用机制 这些细胞中的稳定性可以部分地由组织中的低氧可用性来解释 然而，HIF在循环造血干细胞中是稳定的， 与来自相同微环境的分化细胞相比，的 在干细胞或分化细胞中调节HIF蛋白的因素主要是不清楚的。测试 假设干细胞可以通过抑制PHD来稳定HIF，我们进行了酵母 以PHD 2为诱饵进行双杂交筛选，发现9个蛋白与PHD 2相互作用。我们专注于 MAGEA 11和DVL 1是两个与胚胎发育和癌症发生有关的基因。 MAGEA 11是一种癌-睾丸抗原，在胚胎组织中表达，但在成人组织中不表达， 在不同组织学的肿瘤中异常表达。DVL基因家族是一个主要的 Wnt信号转导途径中的中间体，显示在干细胞中发挥作用 上维护我们获得了MAGEA 11抑制PHD 2的几条证据，PHD 2是一个主要的 通过增加HIF降解的稳定性和转录激活， HIF-1a。我们发现MAGEA 11的表达在维甲酸诱导的细胞凋亡过程中下调。 与HIF-1 α一致的人畸胎癌细胞系NTERA 2的分化， HIF-2a。关于MAGEA 11抑制PHD 2和激活HIF的手稿目前在 准备.缺氧与Wnt信号通路之间的交叉作用研究 PHD 2-DVL 1相互作用证实了这两种蛋白质结合， 负调控相应通路的终点。比如说， PHD 2的过表达减缓了Wnt信号转导，DVL的过表达也减缓了Wnt信号转导。 抑制PHD 2活性。正在进行的工作是确定生物系统， 这种相互作用有效地起作用以调节细胞的干/分化潜能。

The direct role of Hypoxia-inducible factors (HIF) in the self-renewal and maintenance of stem and pluripotent cells is supported by several observations. First, HIF is an important partner of the Notch signaling pathway involved in transcriptional activation of Notch target genes necessary to maintain neural and myogenic stem cells in an undifferentiated state. Second, HIF-2 transcriptionally activates Oct-4 gene expression, thereby contributing to defective hematopoietic stem cell differentiation, and large embryonic stem cell-derived tumors characterized by an increased number of undifferentiated cells. The mechanism of HIF stabilization in these cells may partially be explained by low oxygen availability in tissues harboring stem cells; however, HIF is stabilized in circulating hematopoietic stem cells under normoxic conditions compared to differentiated cells from the same microenvironment. The factors regulating HIF protein in stem or differentiated cells are mainly unclear. To test the hypothesis that stem cells may stabilize HIFs by inhibiting PHDs we performed a yeast two-hybrid screen using PHD2 as bait and found 9 proteins interacting with PHD2. We focused on two genes that are implicated embryonal development and cancer initiation, MAGEA11 and DVL1. MAGEA11 is a cancer-testis antigen that is expressed in embryonic but not in adult tissues and is aberrantly expressed in tumors of different histology. The DVL gene family is a major intermediate in the Wnt signal transduction pathway, shown to play a role in stem cells maintenance. We obtained several lines of evidence that MAGEA11 inhibits PHD2, a major regulator of HIF degradation through increased stabilization and transcriptional activation of HIF-1a . We found that MAGEA11 expression is downregulated during retinoic acid-induced differentiation of the human teratocarcinoma cell line NTERA2 in concordance with HIF-1a and HIF-2a. The manuscript on MAGEA11 inhibition of PHD2 and activation of HIF is currently in preparation. The study on putative crosstalk between hypoxia and Wnt pathways originating from PHD2-DVL1 interaction confirmed that these two proteins bind and that an increase in abundance of either of them negatively regulates the endpoint of the corresponding pathway. For example, overexpression of PHD2 slows down the Wnt signal transduction and an overexpression of DVL inhibits PHD2 activity. Work is underway to identify the biological system where this interaction effectively functions to regulate stem/differentiation potential of the cell.