Signaling Pathways in Arterial Endothelial Cells

Background: Both total astragalus saponins (AST) and it’s main component astragaloside IV (ASIV) have been used in China as cardiovascular protective medicines. However, the anti-inflammatory activities that are beneficial for cardiovascular health have never been compared directly and the molecular mechanisms remain unresolved. This study was conducted to compare the inhibitory effects of these drugs on TNFa-induced cell responses, related signaling pathways, and the underlying mechanisms in mouse arterial endothelial cells. Methodology/Principal Findings: Real-time qRT-PCR was performed to determine the expression of cell adhesion molecule (CAM) genes. Immunofluorescent staining was used to detect the nuclear translocation of transcription factor NF-kB-p65. Western Blot analysis was used to identify TNFa-induced NF-kB-p65 phosphorylation, IkBa degradation, and caspase-3 cleavage. Cell surface proteins were isolated and TNFa receptor-1(TNFR1) expression was determined. The results suggest that both AST and ASIV attenuate TNFa-induced up-regulation of CAMs mRNA and upstream nuclear translocation and phosphorylation of NF-kB-p65. However, TNFR1-mediated IkBa degradation, cleavage of caspase-3 and apoptosis were inhibited only by AST. These differences in the actions of AST and ASIV could be explained by the presence of other components in AST, such as ASII and ASIII, which also had an inhibitory effect on TNFR1-induced IkBa degradation. Moreover, AST, but not ASIV, was able to reduce TNFR1 protein level on the cell surface. Furthermore, mechanisti