title: Transient activation of transgene expression by hydrodynamics-based injection may cause rapid decrease in plasmid DNA expression.
abstract: The intranuclear disposition of exogenous DNA is quite important for the therapeutic effects of the administered DNA. The expression efficiency from one copy of exogenous DNA delivered by hydrodynamics-based injection dramatically decreases over time, and this 'silencing' occurs without CpG methylation. In this study, naked luciferase-plasmid DNA was delivered into mouse liver by hydrodynamics-based injection, and modifications of the histones bound to the plasmid DNA were analyzed by a chromatin immunoprecipitation (ChIP) analysis. In addition, the effects of a second hydrodynamics-based injection on the expression from the plasmid DNA were examined. The ChIP analysis revealed that the modification status of histone H3 remained constant from 4 h to 4 weeks. Surprisingly, the injection of saline without DNA enhanced the luciferase expression from the preexisting DNA administered 4 and 14 days previously. Our results suggest that histone modification plays no role in the silencing. Instead, our data suggest that the transgene expression is activated by the hydrodynamics-based injection manipulation, and that the return from the activated status causes the silencing.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ochiai
authors.forename: M
authors.initials: M
authors.lastname: Fujimuro
authors.forename: H
authors.initials: H
authors.lastname: Yokosawa
authors.forename: H
authors.initials: H
authors.lastname: Harashima
authors.forename: H
authors.initials: H
authors.lastname: Kamiya
mesh_terms: D000818:Animals; D047369:Chromatin Immunoprecipitation; D005260:Female; D015870:Gene Expression; D020868:Gene Silencing; D015316:Genetic Therapy / Q000379:methods*; D006657:Histones / Q000378:metabolism; D007267:Injections / Q000379:methods; D008099:Liver / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D010957:Plasmids; D013997:Time Factors; D019076:Transgenes
chemical_list: D006657:Histones; D008156:Luciferases