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.
Laboratoire de Biochimie Médicale, C.J.F. INSERM 88.06, U.F.R. de Médecine, Clermont-Ferrand, France.
A
A
Bruhat
D
D
Dréau
M E
ME
Drake
S
S
Tourmente
S
S
Chapel
J L
JL
Couderc
B
B
Dastugue
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