title: Hepatocyte-specific gene expression from integrated lentiviral vectors.
abstract: BACKGROUND
  For many applications, efficient gene therapy will require long-term, organ-specific therapeutic gene expression. Lentiviral vectors based on HIV-1 are promising gene delivery vehicles due to their ability to integrate transgenes into non-dividing cells. Many experimental vectors express transgenes under the control of the cytomegalovirus (CMV) immediate-early gene promoter. Although this promoter directs strong gene expression in vitro, it may be shut off rapidly in vivo. This study explores the potential of HIV-1-based vectors to transduce hepatocytes and compares gene expression from different promoters in integrated vectors.
  
  
  METHODS
  HIV-1-based vector plasmids expressing the green fluorescent protein (GFP) under the control of the CMV promoter, the alpha-1 antitrypsin gene promoter or promoters derived from the hepatitis B virus (HBV) genome were used to compare expression in transfected and transduced cell lines.
  
  
  RESULTS
  Hepatocyte cell lines differed strikingly in their transfectability. Transduction with replication-deficient HIV-1-based vector particles incorporating the different promoter elements was uniformly effective in hepatocyte and non-hepatocyte lines. However, in hepatocytes, only the CMV, alpha-1 antitrypsin and HBV core but not HBV surface promoters were able to produce GFP expression. Addition of the HBV enhancer 2 element improved the transducing ability of the HBV surface promoter and suppressed expression in non-hepatocytes increasing specificity for hepatocytes.
  
  
  CONCLUSIONS
  Integrated lentiviral vectors can be used to direct transgene expression in liver cells both promiscuously and specifically. Promoters derived from the alpha-1 antitrypsin gene or HBV are alternatives to the CMV promoter. Inclusion of the HBV enhancer 2 permits strong liver-specific gene expression in vitro.
authors.affiliation: Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Nash
authors.forename: Bushra
authors.initials: B
authors.lastname: Jamil
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Maguire
authors.forename: Graeme J M
authors.initials: GJ
authors.lastname: Alexander
authors.forename: Andrew M L
authors.initials: AM
authors.lastname: Lever
mesh_terms: D019677:Artificial Gene Fusion; D002460:Cell Line; D003587:Cytomegalovirus / Q000235:genetics; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D018014:Gene Transfer Techniques; D017930:Genes, Reporter / Q000235:genetics / Q000502:physiology; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics* / Q000627:therapeutic use; D049452:Green Fluorescent Proteins / Q000235:genetics; D015497:HIV-1 / Q000235:genetics* / Q000502:physiology; D006515:Hepatitis B virus / Q000235:genetics; D022781:Hepatocytes / Q000378:metabolism* / Q000821:virology; D006801:Humans; D011401:Promoter Regions, Genetic / Q000502:physiology; D014161:Transduction, Genetic; D014162:Transfection; D016662:Virus Integration / Q000502:physiology; D000515:alpha 1-Antitrypsin / Q000235:genetics
chemical_list: D000515:alpha 1-Antitrypsin; D049452:Green Fluorescent Proteins