Map, but not EspF, induces breast epithelial cell apoptosis through ERK/DRP-1 pathway

The incidence of bovine mastitis induced by enteropathogenic Escherichia coli (EPEC) in the environment has increased, but the mechanism of effector-Map and -EspF secreted by EPEC in breast epithelial cells is not clear. Therefore, this study focused on Map and EspF to explore the role of these two virulence factors in EPEC-induced bovine mastitis. We established Δmap and/or ΔEspF mutant strains to explore their role in EPEC-induced bovine mastitis. It was found that both Map and EspF could affect the mitochondrial membrane potential, apoptosis, and tight junctions in MAC-T cells. In addition, we also found that Map could affect the ERK signaling pathway. In order to further verify the effect of Map on the ERK signaling pathway, we introduced an ERK inhibitor (PD98059) and pc DNA3.1 plasmid with the map gene. It was found that DRP-1 and apoptosis were no longer affected by Map. In summary, the study implies that E. coli can promote breast epithelial cell apoptosis and destroy tight junctions through Map and EspF. However, Map, but not EspF, induces breast epithelial cell apoptosis through the ERK-DRP-1 pathway.