Paradoxical effects of recombinant mouse beta-interferon on different expression levels of intracisternal A particle genes.

We have studied the effect of mouse recombinant beta-Interferon on the expression of the intracisternal A particle (IAP) genes in a transformed mouse fibroblast cell line. Northern and immunoprecipitation analysis showed an increase in specific transcripts and polypeptides. Run-on experiments on isolated nuclei and transfection assays with an IAP long terminal repeat construct, coupled with the chloramphenicol acetyl transferase gene, showed no enhancement of the transcription rate following beta-IFN treatment. This suggests that the increase in IAP expression depends on a post-transcriptional event. Electron microscopic analysis revealed that in spite of the higher levels of IAP related polypeptides, the number of particles was significantly reduced by interferon.