Molecular study of the retrovirus-like transposable element 412, a 20-OH ecdysone responsive repetitive sequence inDrosophilacultured cells

Publisher Website
Google Scholar
Abstract
Used at a physiological concentration, the steroid hormone 20-hydroxyecdysone (20-OHE) induces, in KC cultured Drosophila melanogaster cells, important and specific changes. Modifications occur at morphological and enzymatic levels. Variations in specific protein synthesis are observed. At the molecular level, 20-OHE particularly induces a decrease in expression of the mobile dispersed genetic element 412. This repeated element which belongs to the "copia-like" family is more widely represented in Kc cells(80 fold)compared to fly cells (25 fold). 412 transcripts are heterogeneous in size, essentially polyadenylated and resticted to the nucleus. A minimal concentration of 10-8 M and a time treatment of 16 hours are necessary to obtain a strong decrease in 412 expression. The similarities between the 412 element and the proviral forms of vertebrate retroviruses are strengthened by the characterization of extrachromosomal circular DNA forms revealed by the 412 probe.Quantifying experiments have shown that the steady state level of such forms is not affected by the steroid treatment.