Abstract
Chemokines play an important role in regulating the complex immune system at the maternal-fetal interface during pregnancy. Among various chemokines, CC motif chemokine ligand 2 (CCL2) plays a role in the recruitment of immune regulatory cells to implantation sites within the endometrium. In cattle, CCL2 is abundantly expressed in the uterine endometrium. However, its intracellular signaling has not been identified. In this study, we examined the effects of CCL2 on bovine endometrial (BEND) cell proliferation. CCL2 stimulated BEND cell proliferation by abundant expression of PCNA, accumulation of cells in the G2/M phase, and activation of the PI3 K/AKT and MAPK signaling pathways. Moreover, CCL2 reduced endoplasmic reticulum stress and restored the inflammation-induced reduction in BEND cell proliferation by regulating the unfolded protein response genes and cytokines. Collectively, these results demonstrated that CCL2 plays a pivotal role in reproductive tissues and may support maternal-fetal interface to improve efficiency of pregnancy.