Abstract
C3H/He inbred mice frequently generate myeloid leukemia after sublethal doses of ionizing radiation. We have previously found that the unique genomic integration of cDNA of retrotransposon, intracisternal A-particle (IAP), reversely transcribed from IAP RNA is frequently detected in radiation-induced myeloid leukemia cells in the C3H/He mice. However, the molecular mechanims of the retrotransposition of repetitive sequence of mouse genome have not been understood. To investigate synthesis of IAP cDNA from IAP RNA in C3H/He mouse, our original methodology to measure reverse transcription in cell lines was expanded to the transgenic mouse systems in this study.
Transgenes designed to express IAP RNA constitutively with unique oligonucleotides as molecular probes were constructed. By the direct injection of the 12.5-14.1 kb transgenes into embryos of C3H/He inbred mouse, we have succesfully generated 19 lines of transgenic mice. Finally, 7 mouse lines with different homogeneous allele of the transgene were established. Occurrence of reverse transcription were confirmed by the detection of unique cDNA molecules derived from transgene RNA in the cells of the transgenic mice. The faint amounts of cDNAs in the various cells in the mice were measured by the quantitative real-time PCR. Higher levels of the cDNAs were observed in radiation sensitive cells including myeloid, intestine and germline cells. The results showed that the transgenic mice is useful to study molecular process of reverse transcription in the retrotransposition.
