Intronic and 5' flanking sequences of the Drosophila beta 3 tubulin gene are essential to confer ecdysone responsiveness.
The expression of the beta 3 tubulin gene is regulated, at the transcriptional level, by the steroid hormone ecdysone, in Drosophila Kc cells. Using a transient expression assay, we show that 360 bp from the first intron of the beta 3 tubulin gene, associated with the 5' flanking sequences, are essential to confer ecdysone inducibility on a minimum promoter driving the chloramphenicol acetyl transferase (CAT) gene. The 5' flanking region contains ecdysone-independent cis-positive elements located in proximity to the promoter. Deletion analysis of the 360 bp intronic region reveals that a fragment of 57 bp is crucial for the ecdysone response of the beta 3 tubulin gene. This fragment contains 5'-TGA(A/C)C-3' motifs homologous to ecdysone responsive elements (EcRE) half sites. Band shift assays show that this 57-bp fragment is bound by three specific complexes. One of them appears to be involved in the level of the ecdysone response.
Bruhat
A
A
Laboratoire de Biochimie Médicale, C.J.F. INSERM 88.06, U.F.R. de Médecine, Clermont-Ferrand, France.
Dréau
D
D
Drake
M E
ME
Tourmente
S
S
Chapel
S
S
Couderc
J L
JL
Dastugue
B
B
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004331:Drosophila melanogaster / Q000235:genetics*; D004440:Ecdysone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D017344:Genes, Insect; D007438:Introns; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects; D014404:Tubulin / Q000096:biosynthesis / Q000235:genetics*
D011993:Recombinant Fusion Proteins; D014404:Tubulin; D004440:Ecdysone