Elevation of Hypertonicity-Induced NFAT5 Promotes Apoptosis of Human Umbilical Vein Endothelial Cells via the NF-B Pathway

Purpose: High salt intake is considered to raise the risk of abdominal aortic aneurysm (AAA), but the underlying mechanism is unclear. The article’s purpose is to verify that high salt led intake to AAA via inducing apoptosis of endothelial cells.

Materials and Methods: Human umbilical vein (HUVEC) morphology was observed and photographed at room temperature under a phase contrast microscope. Cell viability was further quantified by using MTS. pEGFP-NFAT5  (nuclear factor of activated T cells 5) containing the coding region for myc-tagged NFAT5 were transfected using Lipofectamine 2000. NFAT5 siRNA and scrambled control siRNAs were transfected into cells using Oligofectamine. Luciferase assay was performed to determine the relative luciferase activity (Renilla/Firefly) using the Dual-Luciferase Reporter Assay System.

Results: Our studies verified that hypertonic medium with excess sodium chloride induced apoptosis of HUVECs, a commonly used cell model to study aortic endothelial cells. Further mechanism studies suggested that hypertonic condition elevated the expression of NFAT5, and high level of NFAT5 was capable of inducing apoptosis of HUVECs. In the investigation of downstream signals of NFAT5, we found that either hypertonic condition or NFAT5 overexpression promoted the activity of the NF-B signaling pathway and subsequently suppressed the expression of antiapoptotic protein Bcl-2.

Conclusions: We demonstrate a novel mechanism that high salt induces apoptosis of endothelial cells via enhancing the NFAT5–NF-B signaling pathway. These findings will extend our knowledge about the pathogenesis of AAA and provide potential drug targets for the treatment of AAA.