Molecular Biology of Channel Catfish Gonadotropin Receptors: 1. Cloning of a Functional Luteinizing Hormone Receptor and Preovulatory Induction of Gene Expression1

There is little known about the molecular biology of piscine gonadotropin receptors, and information about gene expression during reproductive development is particularly lacking. We have cloned the LH receptor (LHR) in the channel catfish (cc), and examined its gene expression throughout a reproduc...

Full description

Saved in:
Bibliographic Details
Published in:Biology of reproduction 2001-03, Vol.64 (3), p.1010-1018
Main Authors: Sampath Kumar, R, Ijiri, Shigeho, Trant, John M
Format: Article
Language:English
Subjects:
Contents
seasonal reproduction
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:There is little known about the molecular biology of piscine gonadotropin receptors, and information about gene expression during reproductive development is particularly lacking. We have cloned the LH receptor (LHR) in the channel catfish (cc), and examined its gene expression throughout a reproductive cycle. A cDNA encoding the receptor was isolated from the testis using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends procedures. It encoded a 696-amino acid protein that showed the greatest homology (46–50% identity) with the known LHRs and lesser similarity with FSH receptors and thyroid-stimulating hormone receptors (44–47% and 42–44% identity, respectively). In addition, two characteristics unique to the LHRs were conserved in the cloned receptor and the encoding gene: presence of an intron corresponding to intron 10 in mammals and turkey and occurrence of a double cysteine residue in the cytoplasmic tail for potential palmitoylation. The ccLHR gene was well expressed in the gonads and kidney and merely detectable in the gills, muscle, and spleen. The isolated cDNA encoded an active ccLHR protein, as the recombinant receptor expressed in COS7 cells activated a cAMP response element-driven reporter gene (luciferase) upon exposure to hCG in a dose-dependent manner. Seasonal changes in the ovarian expression of the ccLHR gene, as examined by measuring the transcript abundance by quantitative real-time RT-PCR, remained rather low during most of the reproductive cycle but was acutely induced around the time of spawning. This pattern of expression correlates well with the reported expression of its ligand (LH) in fishes and concurs with the notion that LH is a key regulator of the periovulatory maturational events.
ISSN:0006-3363
1529-7268
DOI:10.1095/biolreprod64.3.1010