title: Correlation between transgen expression and plasmid DNA loss in mouse liver.
abstract: BACKGROUND
  Transgene expression from plasmid DNA is dependent on the expression efficiency per plasmid and the amount of intranuclear plasmid. In the present study, intranuclear dispositions of two types of plasmid DNAs (i.e. the pCpGfree and pLIVE plasmids) that maintain transgene expression in mouse liver were analyzed. In addition, the relationship between transgene expression and plasmid stability in the nucleus was examined.
  
  
  METHODS
  First, the pCpGfree and pLIVE plasmid DNAs, bearing the mouse secreted alkaline phosphatase (Seap) gene, were administered into mouse liver by the hydrodynamics-based method. Next, various Seap-plasmid DNAs containing different promoters, upstream and downstream sequences, and backbones were injected into mice, and both SEAP expression and plasmid DNA amounts were monitored for 28 days.
  
  
  RESULTS
  At the 14- and 28-day time points, the amount of the pCpGfree plasmid DNA was one order of magnitude less than that of the pLIVE plasmid. Meanwhile, the expression efficiency per plasmid was one order of magnitude more efficient for the pCpGfree plasmid DNA. Moreover, the administration of various Seap-plasmid DNAs revealed that negative correlations exist between plasmid stability and SEAP expression level.
  
  
  CONCLUSIONS
  The results obtained suggest that the pCpGfree plasmid is unstable from the viewpoint of quantity and maintains transgene expression by its high expression efficiency and also that transgene expression negatively affects the stability of plasmid DNA.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Togashi
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Harashima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kamiya
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics*; D000818:Animals; D005260:Female; D015870:Gene Expression; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D010957:Plasmids / Q000235:genetics*; D011401:Promoter Regions, Genetic; D019076:Transgenes / Q000235:genetics*
chemical_list: D000469:Alkaline Phosphatase
keywords: nonviral vector; plasmid stability; transgene expression