title: IFN-λ Inhibits MiR-122 Transcription through a Stat3-HNF4α Inflammatory Feedback Loop in an IFN-α Resistant HCV Cell Culture System.
abstract: BACKGROUND
  HCV replication in persistently infected cell culture remains resistant to IFN-α/RBV combination treatment, whereas IFN-λ1 induces viral clearance. The antiviral mechanisms by which IFN-λ1 induces sustained HCV clearance have not been determined.
  
  
  OBJECTIVE
  To investigate the mechanisms by which IFN-λ clears HCV replication in an HCV cell culture model.
  
  
  METHODS
  IFN-α sensitive (S3-GFP) and resistant (R4-GFP) cells were treated with equivalent concentrations of either IFN-α or IFN-λ. The relative antiviral effects of IFN-α and IFN-λ1 were compared by measuring the HCV replication, quantification of HCV-GFP expression by flow cytometry, and viral RNA levels by real time RT-PCR. Activation of Jak-Stat signaling, interferon stimulated gene (ISG) expression, and miRNA-122 transcription in S3-GFP and R4-GFP cells were examined.
  
  
  RESULTS
  We have shown that IFN-λ1 induces HCV clearance in IFN-α resistant and sensitive replicon cell lines in a dose dependent manner through Jak-Stat signaling, and induces STAT 1 and STAT 2 activation, ISRE-luciferase promoter activation and ISG expression. Stat 3 activation is also involved in IFN-λ1 induced antiviral activity in HCV cell culture. IFN-λ1 induced Stat 3 phosphorylation reduces the expression of hepatocyte nuclear factor 4 alpha (HNF4α) through miR-24 in R4-GFP cells. Reduced expression of HNF4α is associated with decreased expression of miR-122 resulting in an anti-HCV effect. Northern blot analysis confirms that IFN-λ1 reduces miR-122 levels in R4-GFP cells. Our results indicate that IFN-λ1 activates the Stat 3-HNF4α feedback inflammatory loop to inhibit miR-122 transcription in HCV cell culture.
  
  
  CONCLUSIONS
  In addition to the classical Jak-Stat antiviral signaling pathway, IFN-λ1 inhibits HCV replication through the suppression of miRNA-122 transcription via an inflammatory Stat 3-HNF4α feedback loop. Inflammatory feedback circuits activated by IFNs during chronic inflammation expose non-responders to the risk of hepatocellular carcinoma.
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Fatma
authors.initials: F
authors.lastname: Aboulnasr
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Sidhartha
authors.initials: S
authors.lastname: Hazari
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Satyam
authors.initials: S
authors.lastname: Nayak
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Partha K
authors.initials: PK
authors.lastname: Chandra
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Panigrahi
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Pauline
authors.initials: P
authors.lastname: Ferraris
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Srinivas
authors.initials: S
authors.lastname: Chava
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology.
authors.forename: Ramazan
authors.initials: R
authors.lastname: Kurt
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Kyongsub
authors.initials: K
authors.lastname: Song
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Asha
authors.initials: A
authors.lastname: Dash
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Balart
authors.affiliation: Microbiology and Immunology Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Garry
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.
authors.forename: Tong
authors.initials: T
authors.lastname: Wu
authors.affiliation: Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA-70112, United States of America.|Department of Medicine, Division of Gastroenterology and Hepatology.
authors.forename: Srikanta
authors.initials: S
authors.lastname: Dash
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D025461:Feedback, Physiological; D005786:Gene Expression Regulation; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics* / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology; D007372:Interferons; D007378:Interleukins / Q000494:pharmacology*; D053613:Janus Kinase 1 / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D012367:RNA, Viral / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D012254:Ribavirin / Q000494:pharmacology; D050795:STAT2 Transcription Factor / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014779:Virus Replication / Q000187:drug effects; D000095022:Interferon Lambda
chemical_list: D000998:Antiviral Agents; D051557:Hepatocyte Nuclear Factor 4; D016898:Interferon-alpha; D007372:Interferons; D007378:Interleukins; D053613:Janus Kinase 1; D035683:MicroRNAs; D012367:RNA, Viral; D012254:Ribavirin; D050795:STAT2 Transcription Factor; D050796:STAT3 Transcription Factor; C496592:HNF4A protein, human; C000624353:interferon-lambda, human; D000095022:Interferon Lambda; C531907:MIRN122 microRNA, human; C494084:STAT2 protein, human; C494086:STAT3 protein, human