Activation and repression ofDrosophilaalcohol dehydrogenase distal transcription by two steroid hormone receptor superfamily members binding to a common response element

Abstract

Developmental activation of the Drosophila alcohol dehydrogenase (Adh) distal promoter is controlled by the Adh adult enhancer (AAE). Within this 150 bp, complex enhancer is a small (12 bp) positive cis-acting element that is required for high levels of distal transcription in adult flies and ADH-expressing tissue culture cells. We previously reported that the steroid receptor superfamily member FTZ-F1 binds to this site. We have identified a second steroid receptor superfamily member, DHR39, which also binds to this site. DHR39 is expressed throughout development in transcripts of several sizes. In situ hybridization to embryos has shown that DHR39 RNA is found primarily in the central nervous system, and not in embryonic tissues that express ADH. FTZ-F1 RNA, however, shows temporal-specific patterns similar to those of the distal promoter. FTZ-F1 and DHR39 have identical amino acids in the 'P-box' of the DNA binding domain, suggesting that they have identical DNA recognition characteristics. By electrophoretic mobility shift analysis we show that a DHR39 fusion protein binds specifically to two FTZ-F1 binding sites. By over expressing the full length DHR39 protein in a transient co-transfection assay we have shown that it represses distal Adh expression in a dosage- and binding site-dependent manner. Over expression of an alternative DHR39 open reading frame that lacks part of the putative ligand binding domain does not alter Adh expression. In contrast, over expression of FTZ-F1 specifically activates distal Adh expression.

Regulation of the EDG84A Gene by FTZ-F1 during Metamorphosis in Drosophila melanogaster

“…This ecdysone response element might be involved in the repression of this gene by ecdysteroids (4). The FTZ-F1 binding site is also recognized by another nuclear receptor, FTZ-F1␤ (also called DHR39) (8,17,27). However, FTZ-F1␤ may not be responsible for the activation of EDG84A, because FTZ-F1␤ is an early ecdysone response gene, and its mRNA is expressed from the mid-third larval instar to early prepupal periods (17), in which EDG84A is repressed.…”

“…3). As FTZ-F1␤ has been shown to be a repressor of the target gene in cultured cells (8,27), it might serve as a repressor of the EDG84A gene by competing with FTZ-F1 for the FTZ-F1 binding site.…”

Direct Repeats Bind the EcR/USP Receptor and Mediate Ecdysteroid Responses in Drosophila melanogaster

“…This leaves open the possibility that the ecdysteroid response mediated by direct repeats DR0G and DR3G in the fat body involves trans-regulatory factors distinct from the EcR/USP heterodimer. Apart from EcR and USP, five other Drosophila nuclear receptors, E75, E78, ␤FTZ-F1, DHR3, and DHR39 (8,31,38,51,63,67), are known to be involved in the 20E genetic cascade activated at the onset of metamorphosis. Recently, Horner et al (24) tested the binding of these seven nuclear receptors, either alone or in pairwise combinations, to DR3G, DR4G, and DR5G.…”

ftz-f1 and Hr39 opposing roles on EcR expression during Drosophila mushroom body neuron remodeling

“…Moreover, both receptors bind in vitro the same site in the Alcohol dehydrogenase (Adh), fushi tarazu (ftz) and new glue (ng) gene [19][20][21] . Opposing in vitro transcriptional activity is reported in the corresponding common binding sites.…”