A novel ecdysone receptor mediates steroid-regulated developmental events during the mid-third instar of Drosophila.
The larval salivary gland of Drosophila melanogaster synthesizes and secretes glue glycoproteins that cement developing animals to a solid surface during metamorphosis. The steroid hormone 20-hydroxyecdysone (20E) is an essential signaling molecule that modulates most of the physiological functions of the larval gland. At the end of larval development, it is known that 20E--signaling through a nuclear receptor heterodimer consisting of EcR and USP--induces the early and late puffing cascade of the polytene chromosomes and causes the exocytosis of stored glue granules into the lumen of the gland. It has also been reported that an earlier pulse of hormone induces the temporally and spatially specific transcriptional activation of the glue genes; however, the receptor responsible for triggering this response has not been characterized. Here we show that the coordinated expression of the glue genes midway through the third instar is mediated by 20E acting to induce genes of the Broad Complex (BRC) through a receptor that is not an EcR/USP heterodimer. This result is novel because it demonstrates for the first time that at least some 20E-mediated, mid-larval, developmental responses are controlled by an uncharacterized receptor that does not contain an RXR-like component.
School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America.
Benjamin F B
BF
Costantino
Daniel K
DK
Bricker
Kelly
K
Alexandre
Kate
K
Shen
John R
JR
Merriam
Christophe
C
Antoniewski
Jenna L
JL
Callender
Vincent C
VC
Henrich
Asaf
A
Presente
Andrew J
AJ
Andres
D000818:Animals; D030801:Animals, Genetically Modified; D004268:DNA-Binding Proteins / Q000502:physiology; D019281:Dimerization; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D004441:Ecdysterone / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D005967:Glue Proteins, Drosophila / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008675:Metamorphosis, Biological / Q000235:genetics / Q000502:physiology*; D011987:Receptors, Steroid / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D019076:Transgenes / Q000502:physiology
C102117:Br protein, Drosophila; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005967:Glue Proteins, Drosophila; D011987:Receptors, Steroid; C424365:Sgs3 protein, Drosophila; D014157:Transcription Factors; C066030:USP protein, Drosophila; C055469:ecdysone receptor; D004441:Ecdysterone