抄録
Mouse genome possesses 2000 copies of intracisternal A-particle (IAP) DNA element. From the element, shorter mRNA is transcribed and the complete cDNA is synthesized by an unique mechanism closely related to retrovirus life-cycle. By an integration of the cDNA into genomic DNA, adjacent gene function is influenced. We have previously found that genomic rearrangement by characteristic insertions of new copies of the IAP cDNA frequently occurs in acute myeloid leukemia cells of C3H/He mouse. Since there are large amounts of IAP-related DNA/RNA molecules in any of mouse cells, it is difficult to analyze the complete IAP cDNA that has the potential to convert genomic information.
To reveal the unique reverse-transcription, we designed a series of IAP genomes for quantification of complete cDNA derived from the RNA molecules. The synthesized IAP genomes were stably integrated to mouse macrophage cell line, RAW264.7. A faint amount of the cDNA from the transgene RNA was successfully measured by real-time PCR in the transformants. Surprisingly, the level of the cDNA was increased in the cells following to exposure to ionizing radiation. This suggests that the radiation not only damages genomic DNA but also stimulates chronic endogenous mutation via IAP cDNA.
