Meeting Abstract

P1.108  Jan. 4   Expression of retinoid-X receptor isoforms in the green crab, Carcinus maenas VAN ORT, K.*; COVI, J.A.; CHANG, E.S.; MYKLES, D.L.; Colorado State University; Colorado State University; University of California, Davis- Bodega Marine Lab; Colorado State University kvanort@simla.colostate.edu

Ecdysteroids are steroid hormones that regulate growth, development, reproduction, and molting in arthropods. The functional ecdysteroid receptor is a heterodimer of the ecdysone receptor (EcR) and a vertebrate retinoid-X receptor (RXR) ortholog, ultraspiracle (USP) in insects or RXR in crustaceans. EcR/RXR heterodimers bind to hormone response elements within the genome to induce expression of early response genes. These early response gene products are transcription factors that induce an ecdysteroid cascade of gene expression. The retinoid X receptor (RXR) is a member of nuclear hormone receptor family proteins. RXR contains two signature domains of nuclear receptor family proteins, namely the DNA-binding domain (DBD) and ligand-binding domain (LBD). The T-box region, located between the DBD and LBD, influences DNA binding properties of the heterodimer. There are multiple isoforms of RXR in the land crab, Gecarcinus lateralis, and fiddler crab, Uca pugilator, which differ in the T-box and LBD. Three partial cDNA sequences encompassing the T-box region of the green crab RXR were cloned using RT-PCR. Two cDNAs were similar to the T(+7) and T(+12) isoforms from land and fiddler crabs. The third encoded a novel sequence, designated the T(+10) isoform. Here we report the use of PCR and high-resolution gel electrophoresis to examine the expression of the three T-box isoforms of green crab RXR in response to elevated ecdysteroids. Supported by NSF (IBN-0342982).