Expression, Structure, Function, and Evolution of Gonadotropin-Releasing Hormone (GnRH) Receptors GnRH-R1SHS and GnRH-R2PEY in the Teleost, Astatotilapia burtoni

Multiple GnRH receptors are known to exist in nonmammalian species, but it is uncertain which receptor type regulates reproduction via the hypothalamic-pituitary-gonadal axis. The teleost fish, Astatotilapia burtoni, is useful for identifying the GnRH receptor responsible for reproduction, because o...

Full description

Saved in:
Bibliographic Details
Published in:Endocrinology (Philadelphia) 2007-10, Vol.148 (10), p.5060-5071
Main Authors: Flanagan, Colleen A, Chen, Chun-Chun, Coetsee, Marla, Mamputha, Sipho, Whitlock, Kathleen E, Bredenkamp, Nicholas, Grosenick, Logan, Fernald, Russell D, Illing, Nicola
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Binding, Competitive
Biological and medical sciences
Brain - metabolism
Cichlids - metabolism
Circadian Rhythm
Cloning, Molecular
Evolution, Molecular
Female
Fundamental and applied biological sciences. Psychology
Gonadotropin-Releasing Hormone - metabolism
Ligands
Male
Phylogeny
Receptors, LHRH - chemistry
Receptors, LHRH - genetics
Receptors, LHRH - metabolism
Receptors, LHRH - physiology
Reproduction - physiology
RNA, Messenger - metabolism
Tissue Distribution
Vertebrates: endocrinology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Multiple GnRH receptors are known to exist in nonmammalian species, but it is uncertain which receptor type regulates reproduction via the hypothalamic-pituitary-gonadal axis. The teleost fish, Astatotilapia burtoni, is useful for identifying the GnRH receptor responsible for reproduction, because only territorial males reproduce. We have cloned a second GnRH receptor in A. burtoni, GnRH-R1SHS (SHS is a peptide motif in extracellular loop 3), which is up-regulated in pituitaries of territorial males. We have shown that GnRH-R1SHS is expressed in many tissues and specifically colocalizes with LH in the pituitary. In A. burtoni brain, mRNA levels of both GnRH-R1SHS and a previously identified receptor, GnRH-R2PEY, are highly correlated with mRNA levels of all three GnRH ligands. Despite its likely role in reproduction, we found that GnRH-R1SHS has the highest affinity for GnRH2 in vitro and low responsivity to GnRH1. Our phylogenetic analysis shows that GnRH-R1SHS is less closely related to mammalian reproductive GnRH receptors than GnRH-R2PEY. We correlated vertebrate GnRH receptor amino acid sequences with receptor function and tissue distribution in many species and found that GnRH receptor sequences predict ligand responsiveness but not colocalization with pituitary gonadotropes. Based on sequence analysis, tissue localization, and physiological response we propose that the GnRH-R1SHS receptor controls reproduction in teleosts, including A. burtoni. We propose a GnRH receptor classification based on gene sequence that correlates with ligand selectivity but not with reproductive control. Our results suggest that different duplicated GnRH receptor genes have been selected to regulate reproduction in different vertebrate lineages.
ISSN:0013-7227
1945-7170
DOI:10.1210/en.2006-1400