L. Vonkalm et al., THE BROAD-COMPLEX DIRECTLY CONTROLS A TISSUE-SPECIFIC RESPONSE TO THESTEROID-HORMONE ECDYSONE AT THE ONSET OF DROSOPHILA METAMORPHOSIS, EMBO journal, 13(15), 1994, pp. 3505-3516
In Drosophila, all of the major metamorphic transitions are regulated
by changes in the titer of the steroid hormone ecdysone. Here we exami
ne how a key regulator of metamorphosis and primary ecdysone response
gene, the Broad-Complex, transmits the hormonal signal to one of its t
argets, the Sgs-4 glue gene. We show that Broad-Complex RNAs accumulat
e in mid third instar larval salivary glands prior to Sgs-4 induction,
as expected for the products of a gene that regulates the timing of S
gs-4 activation. The Broad-Complex codes for a family of zinc finger t
ranscriptional regulators. We have identified a number of binding site
s for these proteins in sequences known to regulate the timing of Sgs-
4 induction, and have used these sites to derive a binding consensus f
or each protein. Some of these binding sites are required in vivo for
Sgs-4 activity. In addition, rbp(+), a genetically defined Broad-Compl
ex function that is required for Sgs-4 induction, acts through these B
road-Complex binding sites. Thus, the Broad-Complex directly mediates
a temporal and tissue-specific response to ecdysone as larvae become c
ommitted to metamorphosis.