Fig 6. IFN-λ decreases HNF4α through STAT3 mediated expression of miR-24.

(A) S3-GFP and R4-GFP cells treated with either IFN-α or IFN-λ for 30 minutes. Cell lysates were measured for pStat3 and total Stat3 activation by Western blot analysis. (B) Huh-7 cells were transfected with pSTAT3-GFP plasmid and cells were treated with either of IFN-α (1000 IU/mL) or IFN-λ (100ng/mL) for 1 hour. Nuclear translocation of the Stat3-GFP fusion protein was measured by fluorescence microscopy. (C) Treatment of R4-GFP cells with a Jak inhibitor prevented the effect of IFN-λ on STAT3 activation and but not the p38 activation. (D and E) S3-GFP and R4-GFP cells were treated with either with IFN-α (1000 IU/mL) or IFN-λ (100ng/mL). Quantification of miR-24 levels was done using qRT-PCR. (F and G) miR-24-3p mimic inhibited the luciferase activity of a reporter plasmid harboring the 3’UTR of HNF4α, while it had no effect on the control plasmid EGFP-Luc. (H). A STAT3 inhibitor (Stattic) specifically inhibits STAT3 phosphorylation in R4-GFP cells but has no effect on STAT1 phosphorylation. (I) Stattic prevents the down regulation of miR-122 by IFN-α and IFN-λ in S3-GFP cells 6 hours after treatment as determined by qRT-PCR. (J and K) Treatment of R4-GFP and S3GFP cells with Stattic prevented the inhibitory effect of IFN-λ on HNF4α, *p≤0.05, **p≤0.01.