Reduced or absent cytotrophoblast invasion of the maternal uterine spiral arterioles is a common clinical finding in studies of pregnancies complicated by preeclampsia, suggesting that the mechanisms mediating invasion of these cells is perturbed. The placenta initially develops in a low oxygen environment of 1-2% oxygen until after the 10th week of pregnancy. During this time oxygen concentration exerts a major influence over trophoblast activity and, hypoxia inducible factors are proposed to be one of many key regulators of first trimester trophoblast behaviour. We used a global gene expression microarray approach to identify signalling pathways and hypoxia-responsive genes of interest involved in invasion of the first trimester trophoblast cell line HTR8/SVneo under hypoxic conditions where HIF-1 was active. Additionally, first trimester placental samples from different gestational age groups were labelled with anti HIF-1α and HIF-2α to evaluate whether HIFs are differentially expressed and localised across two periods of placental development: (1) early first trimester characterised by hypoxia (6-8 weeks) and (2) late first trimester after initiation of maternal blood flow into the placenta (10-12 weeks). Invasion of HTR8/SVneo was assessed in real-time and was significantly increased in 1% compared with 5% and 21% oxygen and did not differ between 5% and 21% oxygen treatments. Eighty-eight genes were differentially expressed between cells cultured in 1% oxygen (where HIF-1α protein was localised to the nucleus) and 5% oxygen (where HIF-1α was mainly cytoplasmic). 65% of the genes were predicted to contain HIF-1α:HIF-1β transcription factor binding sites. While HIF-2α staining intensity in trophoblasts of late first trimester placenta was higher than early first trimester (+57%) the percentage of positively stained trophoblast nuclei did not differ between the two time points. There was no difference in the expression level of any of the hypoxia responsive genes of interest, IGFBP3, P4HA1, P4HA2, ANGPTL4 and MMP1 between early and late first trimester placenta. While HIF-1α and its downstream targets are clearly induced in HTR8/SVneo during in vitro hypoxic conditions, it appears that hypoxia inducible factors and genes are not altered throughout the first 7-12 weeks of placental development, during which the onset of maternal blood flow to the intervillous space takes place.

中文翻译：

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低氧诱导的HIF-1 / HIF-2活性改变滋养细胞的转录调控并促进侵袭。

在妊娠并发先兆子痫的研究中，母体子宫小动脉的滋养层细胞浸润减少或缺失是常见的临床发现，提示介导这些细胞浸润的机制受到干扰。胎盘最初在氧气含量为1-2％的低氧环境中发育，直到怀孕第10周后。在这段时间里，氧气浓度对滋养层的活性产生主要影响，缺氧诱导因子被认为是孕早期滋养层行为的许多关键调节因子之一。我们使用了一种全局基因表达微阵列方法来确定在HIF-1活跃的低氧条件下参与妊娠早孕滋养层细胞系HTR8 / SVneo入侵的信号通路和低氧应答基因。此外，用抗HIF-1α和HIF-2α标记来自不同胎龄组的早孕胎盘样本，以评估HIFs是否在两个胎盘发育期之间差异表达和定位：（1）早孕期以缺氧为特征（6-8周） ）和（2）孕产妇血液开始流入胎盘后（10-12周）。实时评估了HTR8 / SVneo的入侵，与5％和21％的氧气相比，HTR8 / SVneo的入侵显着增加，并且在5％和21％的氧气处理之间没有差异。在1％氧气（其中HIF-1α蛋白位于细胞核中）和5％氧气（其中HIF-1α主要为细胞质）中培养的细胞之间，有88个基因差异表达。预计65％的基因包含HIF-1α：HIF-1β转录因子结合位点。虽然早孕晚期胎盘滋养细胞中的HIF-2α染色强度高于孕早期早期（+ 57％），但在两个时间点之间，阳性染色的滋养细胞核的百分比没有差异。妊娠早期和晚期胎盘之间任何感兴趣的缺氧反应基因，IGFBP3，P4HA1，P4HA2，ANGPTL4和MMP1的表达水平均无差异。尽管在体外低氧条件下，HTR-1 /α及其下游靶标在HTR8 / SVneo中被明显诱导，但似乎低氧诱导因子和基因在整个胎盘发育的最初7-12周内没有改变，在此期间，母体血液开始发作。流向空隙空间。