Interferon α increases metalloproteinase-13 gene expression through a polyomavirus enhancer activator 3-dependent pathway in hepatic stellate cells

Background/AimsTo determine the effects of IFNα on MMP-13 gene expression in primary culture of hepatic stellate cells.MethodsWe measured MMP-13 mRNA, MMP-13 protein, MMP-13 luciferase activity, binding of AP1 and PEA3 to DNA, and binding of PEA3 to Jak1 and Stat1.ResultsIFNα increased MMP-13 mRNA, MMP-13 protein, and luciferase activity in cells transfected either with a luciferase plasmid driven by the MMP-13 promoter or with the same plasmid in which the AP1 binding site has been mutated. IFNα induced the binding of nuclear proteins to a radiolabeled PEA3 probe, but not to a AP1 probe. Supershift assays demonstrated that PEA3 and Stat1 are implicated in the formation of this complex. Immunoprecipitation assays showed that PEA3 interacts physically with Stat1 and that IFNα treatment increases this interaction. Downregulation of PEA3 or JAK1 with appropriated siRNAs or mutation of the PEA3 binding site in the MMP-13 promoter abrogated the effects of IFNα on MMP-13 gene expression. Finally, IFNα induced the binding of PEA3 to JAK1, as well as PEA3 tyrosine and serine phosphorylation.ConclusionsIFNα determines the binding of PEA3 to JAK1 and its tyrosine phosphorylation. Activated PEA3 binds to MMP-13 promoter and activates its expression.