Figure 3.

Mechanism of action of bile-derived exosomes in the normal body. Normal hepatocytes or bile duct cells secrete exosomes into bile. Exosomes in bile are enriched in the primary cilia; on the one hand, exosomes can inhibit the formation of cAMP and thus suppress the phosphorylation of ERK1/2 and ELK-1 to finally reduce the proliferation of bile duct cells. On the other hand, exosomes in contact with the cilia inhibit Cdc25A and bile duct cell proliferation by increasing miR-15A levels. All physiological processes are based on the premise that exosomes are enriched in the primary cilia.