RU486-inducible and liver-specific expression of IL-12 gene in mice / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the inducible ability of plasmid DNA carrying a RU486 regulatory system.Methotis Plasmid pRS22 containing RU486 regulatory system,liver specific promoter and transgene IL-12 was injected into mice by hydrodynamic injection.RU486 was injected intraperitoneally into mice at difierent time points after plasmid administration.The IL-12 1evel in serum was tested by an ELISA kit.The distribution and inducible expression of pRS22 in mice were assayed by measuring DNA,RNA and protein levels by PCR,RT-PCR and immunohistochemical staining.Resuits To determine the duration of the activity of plasmid pRS22,mice injected with 10μg of pRS22 were treated repeatedly with 250μg/kg of RU486 per 7 days after hydrodynamic injection of plasmid.IL-12 expression in serum abruptly increased to peak was detected at 10 h after induction and declined to baseline on day 6.Though peak values of IL-12 decreased gradually after each induction,IL-12 in serum could be induced until 15 weeks after plasmid administration.A total of 5μg of pRS22 was injected into mice to detect the effect of different induction manners on the IL-12 expression.The mice were treated with RU486 per day or per 2 days iil 6 days,respectively.The induction per 2 days resulted in a wavelike pattern of serum IL-12 expression with peak lev-els on the day of induction alternating with lower values on the following day.In contrast,sustained levels of IL-12 could be achieved by administering RU486 per day.Plasmid DNA and GLp65 mRNA were detected in liver of mice with or without RU486 until at least day 28 after plasmid administration.However,IL-12 p35 mRNA was detected only in the liver of mice with RU486 induction.IL-12 immunohistochemical staining in liver demonstrated that IL-1 2 expressed predominantly in the hepatocytes near the surface of liver or between the central vein and portal area after induction with RU486.In contrast,no IL-12 expression was observed in the hepatocytes after induction with sesame oil.Conclusion Tight temporal and spatial control of transgene IL-12 expression could be achieved by RU486 regulatory system driven by liver specific promoter.