Transcriptional activation of the cloned Heliothis virescens (Lepidoptera)ecdysone receptor (HvEcR) by MuristeroneA

Ecdysteroids play an important role during insect development. We report he re the isolation and characterisation of an Ecdysone receptor (EcR) homolog ue from Heliothis virescens (HvEcR) and present evidence supporting the HvE cR active role as an active component of the native insect receptor. Alignm ent of the deduced amino acid sequence of HvEcR with those of EcRs from oth er species confirmed its membership of this family and showed that it is cl osely related to the B1 isoform of Drosophila melanogaster. Northern blot a nalysis showed that two transcripts (6.0 and 6.5 kb) were recognised by a p robe spanning the DNA and ligand binding domains of the HvEcR. Genomic Sout hern blots showed that the HvEcR is encoded by a single copy gene. Two line s of evidence towards the functional activity of the HvEcR are presented. I n vitro transcribed and translated HvEcR showed specific binding to hsp27 a nd pall response elements in the presence of CfUSP. Stable expression of Hv EcR in 293 cells induced reporter gene activity in the presence of murister oneA in a dose dependant manner while dexamethasone failed to activate. (C) 1999 Elsevier Science Ltd. All rights reserved.