title: Mutual antagonism between circadian protein period 2 and hepatitis C virus replication in hepatocytes.
abstract: BACKGROUND
  Hepatitis C virus (HCV) infects approximately 3% of the world population and is the leading cause of liver disease, impacting hepatocyte metabolism, depending on virus genotype. Hepatic metabolic functions show rhythmic fluctuations with 24-h periodicity (circadian), driven by molecular clockworks ticking through translational-transcriptional feedback loops, operated by a set of genes, called clock genes, encoding circadian proteins. Disruption of biologic clocks is implicated in a variety of disorders including fatty liver disease, obesity and diabetes. The relation between HCV replication and the circadian clock is unknown.
  
  
  METHODS
  We investigated the relationship between HCV core infection and viral replication and the expression of clock genes (Rev-Erbα, Rorα, ARNTL, ARNTL2, CLOCK, PER1, PER2, PER3, CRY1 and CRY2) in two cellular models, the Huh-7 cells transiently expressing the HCV core protein genotypes 1b or 3a, and the OR6 cells stably harboring the full-length hepatitis C genotype 1b replicon, and in human liver biopsies, using qRT-PCR, immunoblotting, luciferase assays and immunohistochemistry.
  
  
  RESULTS
  In Huh-7 cells expressing the HCV core protein genotype 1b, but not 3a, and in OR6 cells, transcript and protein levels of PER2 and CRY2 were downregulated. Overexpression of PER2 led to a consistent decrease in HCV RNA replicating levels and restoration of altered expression pattern of a subset of interferon stimulated genes (ISGs) in OR6 cells. Furthermore, in liver biopsies from HCV genotype 1b infected patients, PER2 was markedly localized to the nucleus, consistent with an auto-inhibitory transcriptional feedback loop.
  
  
  CONCLUSIONS
  HCV can modulate hepatic clock gene machinery, and the circadian protein PER2 counteracts viral replication. Further understanding of circadian regulation of HCV replication and rhythmic patterns of host-hosted relationship may improve the effectiveness of HCV antiviral therapy. This would extend to hepatic viral infections the current spectrum of chronotherapies, implemented to treat metabolic, immune related and neoplastic disease.
authors.affiliation: Gastroenterology Unit, IRCCS Casa Sollievo della Sofferenza, Hospital San Giovanni Rotondo, FG, San Giovanni, Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Benegiamo
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Mazzoccoli
authors.forename: Francesco
authors.initials: F
authors.lastname: Cappello
authors.forename: Francesca
authors.initials: F
authors.lastname: Rappa
authors.forename: Nunzia
authors.initials: N
authors.lastname: Scibetta
authors.forename: Jude
authors.initials: J
authors.lastname: Oben
authors.forename: Azzura
authors.initials: A
authors.lastname: Greco
authors.forename: Roger
authors.initials: R
authors.lastname: Williams
authors.forename: Angelo
authors.initials: A
authors.lastname: Andriulli
authors.forename: Manlio
authors.initials: M
authors.lastname: Vinciguerra
authors.forename: Valerio
authors.initials: V
authors.lastname: Pazienza
mesh_terms: D000328:Adult; D000368:Aged; D002460:Cell Line; D045744:Cell Line, Tumor; D005260:Female; D016679:Genome, Viral / Q000235:genetics; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D006526:Hepatitis C / Q000235:genetics / Q000821:virology; D022781:Hepatocytes / Q000378:metabolism* / Q000821:virology*; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology / Q000821:virology; D008297:Male; D008875:Middle Aged; D056950:Period Circadian Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000096:biosynthesis; D014758:Viral Core Proteins / Q000235:genetics; D014779:Virus Replication
chemical_list: C421902:PER2 protein, human; D056950:Period Circadian Proteins; D012367:RNA, Viral; D014758:Viral Core Proteins; C069130:nucleocapsid protein, Hepatitis C virus