Nornicotine impairs endothelial cell-cell adherens junction complexes in EA.hy926 cell line via structural reorganization of F-actin

The aim of the study was to estimate the effect of nornicotine on endothelial EA.hy926 cells in the context of its impact on cell-cell junctions. The objective of the study was to determine the relationship between junctional proteins and F-actin after treating the cells with nornicotine. After 24 h of cell exposure to 0.08, 0.12, and 0.16 ng/mL nornicotine, analysis was performed of cell death, cell migration, ultrastructure, and colocalization of beta-catenin/F-actin and zonula occludens (ZO)-1/F-actin. Our study did not reveal any alterations in EA.hy926 cell line survival following treatment with nornicotine. However, nornicotine exerted disparate effects on cell migration and led to changes in both the ultrastructure and organization of cell-cell junctional complexes and F-actin. Moreover, the cell migration observed in the experiments performed in the present work negatively correlated with the number of Weibel-Palade bodies seen through transmission electron microscopy (TEM). Moreover, the mechanism of cell migration promotion was VEGF-independent, and the decrease in the number of Weibel-Palade bodies resulted from nornicotine-induced F-actin depolymerization. In conclusion, the present study demonstrated that low concentrations of nornicotine do not affect cell survival, but promote cell movement and impair adherens junctions through changes in F-actin organization. Our results indicate for the first time the effect of nornicotine on endothelial EA.hy926 cells and suggest that nornicotine may induce transmigration pathways and, consequently, facilitate the transendothelial migration of monocytes associated with atherosclerosis.