title: Molecular study of the retrovirus-like transposable element 412, a 20-OH ecdysone responsive repetitive sequence in Drosophila cultured cells.
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 enzymatical 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 restricted 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 decrease is at least an effect on these sequences at the transcriptional level. Structural 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.
authors.affiliation: UA CNRS 360, Laboratoire de Biochimie Médicale, Faculté de Médecine, Clermont-Ferrand, France.
authors.forename: D
authors.initials: D
authors.lastname: Micard
authors.forename: J L
authors.initials: JL
authors.lastname: Couderc
authors.forename: M L
authors.initials: ML
authors.lastname: Sobrier
authors.forename: G
authors.initials: G
authors.lastname: Giraud
authors.forename: B
authors.initials: B
authors.lastname: Dastugue
mesh_terms: D000818:Animals; D002460:Cell Line; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D004440:Ecdysone / Q000494:pharmacology*; D005111:Extrachromosomal Inheritance; D005786:Gene Expression Regulation / Q000187:drug effects*; D012332:RNA, Heterogeneous Nuclear / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D004251:DNA Transposable Elements; D012332:RNA, Heterogeneous Nuclear; D004440:Ecdysone; D004262:DNA Restriction Enzymes