Investigation of the Transcription in C6 Cells Trapped by a Novel Gene Trap Vector of the Convergent Type

The interference of transcription by antisense transcripts is now regarded as one of the regulatory mechanisms of gene expression. The overlapping of genes in opposite strands has recently attracted much attention because of their potential association with human diseases. The regulatory mechanism of the overlapping gene itself is also of considerable interest from the view point of gene expression. We designed a novel gene trap vector (GTV) that can be transcribed bidirectionally. It contained promoters, dual and orientation-specific reporter genes (β-galactosidase and green fluorescent protein), drug-resistant genes, and SV40 polyadenylation signal flanked by loxP sites. C6 cell lines stably integrated with the GTV were established by selection with antibiotics. Expression patterns of sense and antisense strands around the trap vector examined by the two reporter genes and their transcripts varied substantially by cell lines: some of this was attributable to interference by antisense transcription, but a portion seemed to be under the control of unknown mechanisms. These results proved the present GTV to be useful as a model system for the study of bidirectional transcription in gene expression.