Liu Yu-Sheng, Huang Zhi-Wei, Qin Ai-Qiong, Huang Yang, Giordano Frank, Lu Qing-Hua, Jiang Wei-Dong
Department of Cardiology, Second Hospital of Shandong University , Jinan, Shandong , China.
Postgrad Med. 2015 Mar;127(2):144-9. doi: 10.1080/00325481.2015.996503. Epub 2014 Dec 24.
Hypoxia inducible factor-1α (HIF-1α) regulates many genes involved in angiogenesis during embryonic development. Epidermal growth factor-like domain 7 (Egfl7) is a specific marker for human arterial endothelial cells that are in an activated state of proliferation, migration, and remodeling. This study evaluates the intricate relationship between HIF-1α and Egfl7 under both hyperoxia and hypoxia states.
The neonatal mice were exposed to either hyperoxia or hypoxia in order to detect the pulmonary and cardiac Egfl7 messenger RNA (mRNA) or protein expression regulated by oxygen tension in vivo by reverse transcriptase polymerase chain reaction or immunohistochemistry staining. Egfl7 expression in HIF-1α null pulmonary endothelial cells in hypoxia conditions and effects of overexpression or knockdown of HIF-1α on Egfl7 expression in human umbilical vein endothelial cells would be clarified in vitro by reverse transcriptase polymerase chain reaction and Western blot, respectively.
Hyperoxia exposure significantly reduced Egfl7 expression in neonatal mice lungs by 36% compared with age-matched normoxia control mice (P < 0.05, n = 6). The pulmonary Egfl7 transcription levels were increased by 1.7- and 1.9-fold in 24 hours and by day 8 in hypoxia groups compared with the normoxia control values (P < 0.05, n = 6). The cardiac Egfl7 mRNA expression was significantly increased by 4.5-fold in the day 8 group compared with the normoxia control values (P < 0.05, n = 6). The expression of Egfl7 decreased significantly in the HIF-1α(-/-) endothelial cells (ECs), which was only 26% of wild-type HIF-1α(+/+) ECs (P < 0.05, n = 3). Hypoxia caused a mild but significant increase of Egfl7 expression in HIF-1α(+/+) ECs (P < 0.05). In vitro, overexpression of HIF-1α enhanced Egfl7 expression, whereas knockdown of HIF-1α reduced Egfl7 expression.
Overexpression of HIF-1α enhanced Egfl7 expression, whereas knockdown of HIF-1α reduced Egfl7 expression. Egfl7 could be a HIF-1α responsive gene regulated by oxygen tension.
缺氧诱导因子-1α（HIF-1α）在胚胎发育过程中调控许多参与血管生成的基因。表皮生长因子样结构域7（Egfl7）是处于增殖、迁移和重塑激活状态的人动脉内皮细胞的特异性标志物。本研究评估了高氧和低氧状态下HIF-1α与Egfl7之间的复杂关系。
将新生小鼠暴露于高氧或低氧环境中，通过逆转录聚合酶链反应或免疫组织化学染色检测体内氧张力调节的肺和心脏Egfl7信使核糖核酸（mRNA）或蛋白表达。分别通过逆转录聚合酶链反应和蛋白质印迹法在体外明确低氧条件下HIF-1α基因敲除的肺内皮细胞中Egfl7的表达，以及HIF-1α过表达或敲低对人脐静脉内皮细胞中Egfl7表达的影响。
与年龄匹配的常氧对照小鼠相比，暴露于高氧环境显著降低了新生小鼠肺中Egfl7的表达，降低了36%（P<0.05，n = 6）。与常氧对照值相比，低氧组在24小时和第8天时肺Egfl7转录水平分别增加了1.7倍和1.9倍（P<0.05，n = 6）。与常氧对照值相比，第8天组心脏Egfl7 mRNA表达显著增加了4.5倍（P<0.05，n = 6）。在HIF-1α基因敲除（-/-）的内皮细胞（ECs）中，Egfl7的表达显著降低，仅为野生型HIF-1α基因敲除（+/+）ECs的26%（P<0.05，n = 3）。低氧导致HIF-1α基因敲除（+/+）ECs中Egfl7表达轻度但显著增加（P<0.05）。在体外，HIF-1α过表达增强了Egfl7的表达，而HIF-1α敲低则降低了Egfl7的表达。
HIF-1α过表达增强了Egfl7的表达，而HIF-1α敲低则降低了Egfl7的表达。Egfl7可能是一个受氧张力调节的HIF-1α反应性基因。
