Sphingosine 1-phosphate induced by hypoxia increases the expression of PAI-1 in HepG2 cells via HIF-1α
Sphingosine 1-phosphate induced by hypoxia increases the expression of PAI-1 in HepG2 cells via HIF-1α
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DOI：
10.3892/mmr.2016.5451
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发表时间：
2016-08-01
影响因子：
3.4
通讯作者：
Fujii, Satoshi
中科院分区：
文献类型：
--
作者：
Sanagawa, Akimasa;Iwaki, Soichiro;Fujii, Satoshi
本课题组最近报道，在永生化的人HepG 2肝细胞系中，1-磷酸鞘氨醇（S1 P）在4小时内增加纤溶酶原激活物抑制剂1型（PAI-1）的转录，PAI-1是纤溶的主要生理抑制剂。本研究旨在阐明这种效应的分子机制。派-1的表达通过逆转录-定量聚合酶链反应和免疫印迹法测定。结果表明，S1 P增加派-1启动子的活性，但不增加缺乏缺氧反应元件（HRE）2的启动子的活性。此外，S1 P瞬时增加缺氧诱导因子（HIF）-1 α的浓度，HIF-1 α是一种能够与HRE结合的转录因子。当HIF-1 α被敲低时，不再观察到S1 P对派-1转录的诱导。鞘氨醇激酶（SPHK）活性增加缺氧。研究表明，用SPHK抑制剂或S1 P受体拮抗剂处理可防止缺氧诱导的HIF-1 α蛋白浓度增加。因此，通过S1 P修饰HIF-1 α的诱导，导致派-1转录增加，可能是血栓形成和随后抑制与缺氧相关的纤维蛋白溶解的有吸引力的治疗靶点。
Our group has recently reported that in the immortal human HepG2 liver cell line, sphingosine 1-phosphate (S1P) increases transcription of plasminogen activator inhibitor type-1 (PAI-1), the major physiological inhibitor of fibrinolysis, within 4 h. The present study aimed to elucidate the molecular mechanisms underlying this effect. PAI-1 expression was measured by reverse transcription-quantitative polymerase chain reaction and immunoblotting. It was demonstrated that S1P increased PAI-1 promoter activity but did not increase the activity of promoters lacking the hypoxia responsive element (HRE) 2. In addition, S1P transiently increased the concentration of hypoxia inducible factor (HIF)-1 alpha, a transcription factor capable of binding to HRE. When HIF-1 alpha was knocked down, the induction of transcription of PAI-1 by S1P was no longer observed. Sphingosine kinase (SPHK) activity is increased by hypoxia. It was demonstrated that increases in the concentration of the HIF-1 alpha protein induced by hypoxia were prevented by treatment with SPHK inhibitor or S1P receptor antagonists. Thus, modification of the induction of HIF-1 alpha by S1P, leading to increased transcription of PAI-1, may be an attractive therapeutic target for thrombosis and consequent inhibition of fibrinolysis associated with hypoxia.