Circular RNA hsa_circ_0004812 impairs IFN-induced immune response by sponging miR-1287-5p to regulate FSTL1 in chronic hepatitis B.

BACKGROUND: The present study aims to explore the functions of circular RNA hsa_circ_0004812 in chronic hepatitis B (CHB) and its underlying molecular mechanisms. METHODS: The expression of circular RNA (circRNA)_0004812 was examined using qRT-PCR and Western blot in blood and liver tissues from CHB patients and healthy volunteers. In the in vitro study, the expression levels of circular RNA hsa_circ_0004812, miR-1287-5p, interferon (IFN)-alpha, IFN-beta were determined using qRT-PCR and Western blotting in HBV-infected hepatoma cells, respectively. Luciferase and biotin pull-down assays were used to investigate the interactions between miR-1287-5p and circ_0004812. RESULTS: Levels of circ_0004812 were upregulated in CHB patients and HBV-infected hepatoma cells. Knockdown of circ_0004812 increased the expression of IFN-alpha and IFN-beta in HBV-infected Huh7 cells. MiR-1287-5p was identified as a target of circ_0004812 whose overexpression inhibited the expression of miR-1287-5p. Additionally, circ_0004812 promoted the expression of Follistatin-related protein (FSTL) 1 through inhibiting miR-1287-5p. Circ_0004812/miR-1287-5p/FSTL1 axis regulated HBV-induced immune suppression. CONCLUSION: Circ_0004812 was identified as a potential target for CHB infection. Circ_0004812 promoted the expression of FSTL1 by inhibiting miR-1287-5p.