Fig. 4.

Fucoidan promotes the activation of ERK pathway and enhances the production of type I interferon in vitro and in vivo. a-d HepG2.2.15 cells were incubated with indicated concentrations of fucoidan for 24 h. a Phospho-ERK, total ERK, phospho-JNK, total JNK, phospho-p38, and total p38 were determined by western blotting. b Phospho-IRF3, total IRF3, phospho-IRF7, and total IRF7 were examined by western blotting. c The production of IFN-α in the culture supernatant was evaluated by ELISA analysis. d The mRNA level of IFN-α in cells was determined by quantitative RT-PCR. e, f C57BL/6 mice were hydrodynamically injected with 10 μg of pHBV1.3 plasmids through the tail vein. The mice were intraperitoneally administrated with 100 mg fucoidan at 0, 1, 3, 5, and 7 days post-infection. e Phospho-ERK, total ERK, phospho-IRF7, and total IRF7 in the liver tissue of infected mice were examined by western blotting at the indicated days post-infection. f The production of IFN-α in the serum was evaluated by ELISA analysis. * p < 0.05, ** p < 0.01, *** p < 0.001, compared to the group without fucoidan treatment. Data shown are representative of three independent experiments