Blocking C/EBP β protects vascular endothelial cells from injury induced by intermittent hypoxia
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Intermittent hypoxia (IH) can damage endothelial cells and lead to apoptosis in obstructive sleep apnea-hypopnea syndrome (OSAHS). Hypoxia induces apoptosis in endothelial cells via upregulation of endothelin-1 (ET-1) and hypoxia inducible factor-1 alpha (HIF-1α) plays a key role in the hypoxic stress response.
We investigated an approach to diminish the negative effect of HIF-1α while maintaining its protective effect.
Human umbilical vein endothelial cells (HUVECs) were subjected to sustained hypoxia (SH) or IH for 24 h, and the responses of HIF-1α, CCAAT/enhancer binding protein beta (C/EBP β), and endothelin-1 (ET-1) were assessed by western blotting. A luciferase reporter system was employed to verify the potential binding site (transcription factor binding site, TFBS) for C/EBP β in the ET-1 promoter. The specificity of regulation of ET-1 by HIF-1α via C/EBP β was evaluated by a lentiviral system. The effects of silencing of C/EBP β on IH-induced apoptosis, vascular endothelial growth factor (VEGF) protein levels, proliferation, and in vitro tube formation were studied.
We found that IH significantly increased HIF-1α, C/EBP β, and ET-1 in HUVECs. Knockdown of HIF-1α or C/EBP β inhibited the upregulation of ET-1 induced by IH. Blocking C/EBP β impaired IH-induced apoptosis but did not affect VEGF expression, proliferation, or in vitro tube formation. C/EBP β was shown to mediate increased ET-1 transcription by HIF-1α through the TFBS, 5′-GTTGCCTGTTG-3′, in ET-1 promoter.
Silencing of C/EBP β can suppress apoptosis but does not affect the protective role of HIF-1α in the hypoxic stress response.
KeywordsOSAHS Intermittent hypoxia HIF-1α ET-1 C/EBP β
Obstructive sleep apnea-hypopnea syndrome
Hypoxia-inducible factor 1-alpha
- C/EBP β
CCAAT/enhancer binding protein beta
Human umbilical vein endothelial cells
Vascular endothelial growth factor
Transcription factor binding site
Fetal bovine serum
Multiplicity of infection
Tris-buffered saline with Tween 20
Sodium dodecyl sulfate-polyacrylamide gel electrophoresis
The National Natural Science Foundation of China provided financial support in the form of national natural science funding (No. 81372529), the Natural Science Fund Project of Shanghai (13ZR1414400); the Innovation Fund Project of Education Commission in Shanghai (14ZZ079); and the Special issue of the Military Medical of Second Military Medical University (2012JS21). The sponsor had no role in the design or conduct of this research.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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