Berberine enhances autophagic flux by activating the Nrf2 signaling pathway in bovine endometrial epithelial cells to resist LPS-induced apoptosis.

Abstract

Berberine exerts many beneficial effects on lipopolysaccharide (LPS)-induced bovine endometrial epithelial cells (BEECs). Recently, we also found that berberine shows significant antiapoptotic and autophagy-promoting activities, but the underlying mechanism has not been elucidated. This research explored the association between the antiapoptotic and autophagy-promoting activities of berberine in LPS-treated BEECs. BEECs were first preconditioned with an inhibitor of autophagic flux (chloroquine [CQ]) for 1 h, treated with berberine for 2 h, and then incubated with LPS for 3 h. Cell apoptosis was assessed by flow cytometry, and autophagy activities were assessed by immunoblot analysis of LC3II and p62. The results indicated that the antiapoptotic activity of berberine was notably inhibited in LPS-treated BEECs after preconditioning with CQ for 1 h. Furthermore, to determine whether berberine promoted autophagy by activating the nuclear factor-erythroid 2 related factor 2 (Nrf2) signaling pathway, we assessed autophagy in LPS-treated BEECs after preconditioning with a signaling pathway inhibitor of Nrf2 (ML385). The results indicated that the enhanced autophagy activity induced by berberine was partially reversed in LPS-treated BEECs after the Nrf2 signaling pathway was disturbed by ML385. In conclusion, berberine enhances autophagic flux to allow resistance to LPS-induced apoptosis by activating the Nrf2 signaling pathway in BEECs. The present study may provide new insight into the antiapoptotic mechanism of berberine in LPS-induced BEECs.