Meeting Abstract

P1.10  Monday, Jan. 4  Identification of Two Novel Type-II GnRH Receptors in the Sea Lamprey, a Basal Vertebrate AQUILINA-BECK, ALLISAN; MACDONALD, CARYN*; KAVANAUGH, SCOTT I.; SOWER, STACIA A.; University of New Hampshire, Durham; University of New Hampshire Durham; University of New Hampshire, Durham; University of New Hampshire, Durham sasower@cisunix.unh.edu

Gonadotropin-releasing hormone (GnRH) is a central regulator of reproductive function in vertebrates, and its function is mediated through a GnRH receptor (GnRHR), a class A 7-transmembrane GPCR. Previously, we identified a unique lamprey GnRH receptor (lGnRH-1) that shares several characteristics of both type-I and type-II vertebrate GnRH receptors (Silver et al., 2005). In this study, we have identified two additional novel GnRH receptors (lGnRHR-2 and -3) in the sea lamprey, a basal vertebrate via the trace files produced by the Genome Sequencing Center at Washington University School of Medicine, St. Louis. Lamprey GnRHR-2 was shown to activate the inositol phosphate (IP system): stimulation with either lGnRH-II or -III led to dose dependent responses in transiently transfected COS7 cells. However, there was no IP response of the transfected GnRHR-2 receptor when treated with lGnRH-I. The cloned receptors retain the conserved structural features and amino acid motifs of other known GnRH receptors and both receptors include a C-terminal tail. The phylogenetic placement, structural and functional features of the lamprey GnRH receptors support that these receptors have retained key ancestral residues and motifs. Further comparative studies on the lamprey GnRHs and respective receptors will help provide clues on the evolution of reproductive mechanisms and insights into our understanding of gene duplication, structure-activity relations, and the molecular evolution and functional diversity of these systems. Supported by NSF IBN-0421923, IOS-0849569, NSF REU Supplement, NH AES Hatch 332 and NIH 5R21RR024477-02 to SAS.