Peptidoglycan (PGN), a component of the outer membrane of Gram-positive bacteria has been implicated in the pathological process of sepsis. However, the molecular mechanism of PGN-induced vascular endothelium dysfunction has not been fully elucidated. Apoptosis signal regulating kinase 1 (ASK1) has been recently reported to play a crucial role in cell apoptosis under various cellular stresses. The purpose of this study was thus to investigate whether PGN-activated ASK1 results in cell apoptosis in human umbilical vascular endothelial cells (HUVECs). PGN was shown to cause a decrease in cell viability in a concentration-dependent manner. Flow cytometric analysis demonstrated that PGN increased the percentage of apoptotic cells. PGN induced ASK1 activation was accompanied by the increased phosphorylation of p38MAPK, a major downstream signaling molecule of ASK1. In addition, PGN was shown to increase apoptotic protein, Bax, expression in HUVECs. Inhibitor of p38MAPK signaling abrogated the PGN-increased DNA fragmentation and Bax expression, suggesting functional crosstalk. The toll-like receptor 2 (TLR2) agonist, Pam3CSK4, was also shown to induce ASK1 activation and p38MAPK phosphorylation, and subsequent cell apoptosis in HUVECs. Our data suggest that ASK1-p38MAPK cascade activation, followed by Bax expression, contributes to PGN-induced cell apoptosis.
Jang, T.-N.; Chiu, P.-T.; Chen, W.-C.; and Hsu, M.-J.
"Molecular mechanisms in peptidoglycan-induced human umbilical vascular endothelial cell apoptosis,"
Journal of Food and Drug Analysis: Vol. 19
, Article 4.
Available at: https://doi.org/10.38212/2224-6614.2237