In Drosophila Kc cells 20-OHE induction of the 60C beta3 tubulin gene expression is a primary transcriptional event.

Abstract

In Drosophila Kc cells, the 60C beta3 tubulin transcription unit, whose expression is induced by 20-hydroxyecdysone (20-OHE), has the same structure as in Drosophila. This gene is characterized by an unusual 5' intron of regulating importance, by an alternatively spliced second intron and by a long 3' transcribed but untranslated region. This gene codes for two beta3 tubulin isoforms with one amino acid difference. We have established that beta3 tubulin gene expression is transcriptionally regulated by the steroid hormone in a time and hormonal concentration-dependent fashion, without requirement of protein synthesis. This implies that this transcriptional induction is a primary event and that this gene is probably a direct target for the 20-OHE receptor.