Role of hypoxia-inducible transcription factors 1alpha and 2alpha in the regulation of plasminogen activator inhibitor-1 expression in a human trophoblast cell line.
The plasminogen activator inhibitors (PAIs) play critical roles in regulating hemostatic and invasive functions of trophoblasts through suppression of plasmin-dependent fibrinolysis and extracellular matrix degradation. The expression of PAI-1 is increased under hypoxic conditions, although the mechanism remains incompletely understood. In the current study we used HTR-8/SVneo cells, a first trimester extravillous trophoblast cell line, and siRNA technology to examine the role of hypoxia-inducible transcription factors (HIFs)-1alpha and -2alpha in the regulation of PAI-1 expression. Using serum-containing and serum-free media culture media it was initially noted that levels of PAI-1, but not PAI-2 protein, were markedly induced by hypoxic (2-3% oxygen) treatment. Under hypoxic conditions, Western blotting revealed that the presence of siRNAs to HIF-1alpha and HIF-2alpha suppressed expression of their respective proteins, whereas treatment with non-targeting and cyclophilin B siRNAs did not. Importantly, incubation with siRNA to HIF-1alpha or HIF-2alpha alone reduced PAI-1 protein levels to a similar extent, with the combined treatment inducing a more profound effect. The presence of HIF siRNAs reduced levels of PAI-1 mRNA as measured by quantitative real-time PCR, indicating that HIF-1alpha and HIF-2 alpha regulate PAI-1 expression at a transcriptional level. These results indicate that both HIF-1alpha and HIF-2alpha play important and similar roles in hypoxia-mediated stimulation of PAI-1 expression in HTR-8/SVneo cells. Our findings provide insight into the physiological regulation of trophoblast PAI-1 expression in early pregnancy when placental oxygen levels are low, as well as a mechanism for over-expression of placental PAI-1 noted in pregnancies with preeclampsia.
Meade
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Department of Obstetrics/Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT 06520-8063, USA.
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Guller
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D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D002460:Cell Line; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis*; D011247:Pregnancy; D034622:RNA Interference; D014327:Trophoblasts / Q000378:metabolism*; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017395:Plasminogen Activator Inhibitor 1; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C051321:SERPINE1 protein, human