[Plasmid DNA expression in the muscle of rat tongue]

To develop rat tongue model for plasmid DNA expression in vivo.

The expression vectors which contained either human-muscle specific promoter or SV40 promoter directing the transcription of reporter gene (E. coli LacZ gene) were used. The straited muscle of the tongue was used as a model system, and expression plasmid DNA was injected directly into Wistar rat tongue. PCR technique, X-gal histochemical staining and Southern blot hybridization were used to analyze reporter gene expression in vivo.

The expression of reporter gene was correlated with the amount of injected DNA and the time of incubation in tongue muscle. beta-galactosidase activity can be detected 24 hours after injection of X-gal staining and even be detected after two months, but the maximal expression level was observed one week later. Coinjection of two expression plasmids resulted in co-expression in the same striated myofibers. E. coli LacZ DNA sequence was found in rat tongue injected with the plasmid DNA by PCR, which demonstrated capacity of the rat tongue myofibers uptaking foreign DNA. The Southern blot analysis showed the injected plasmid DNA existed outside the genome of rat muscle cells. No integration was detected.

Direct plasmid DNA injection into tongue muscle was a simple and efficient approach to transfer foreign gene into striated muscle cells, and tongue was a good model for analyzing exogenous gene expression.