Addition of a carboxy-terminal tail to the normally tailless gonadotropin-releasing hormone receptor impairs fertility in female mice.

Chirine Toufaily,Ying Wang,Dominic Devost,Yiming Cui,Derek Boerboom,Terence E Hébert,Frederik Steyn,Yeu-Farn Lin,Yorgui Santiago-Andres,Jérôme Fortin,Aylin C Hanyaloglu,Evelyne Lapointe,Daniel J Bernard,Xiang Zhou,Tatiana Fiordelisio,Ferdinand Roelfsema,Carlos Ai Alonso

doi:10.7554/elife.72937

Abstract

Gonadotropin-releasing hormone (GnRH) is the primary neuropeptide controlling reproduction in vertebrates. GnRH stimulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) synthesis via a G-protein-coupled receptor, GnRHR, in the pituitary gland. In mammals, GnRHR lacks a C-terminal cytosolic tail (Ctail) and does not exhibit homologous desensitization. This might be an evolutionary adaptation that enables LH surge generation and ovulation. To test this idea, we fused the chicken GnRHR Ctail to the endogenous murine GnRHR in a transgenic model. The LH surge was blunted, but not blocked in these mice. In contrast, they showed reductions in FSH production, ovarian follicle development, and fertility. Addition of the Ctail altered the nature of agonist-induced calcium signaling required for normal FSH production. The loss of the GnRHR Ctail during mammalian evolution is unlikely to have conferred a selective advantage by enabling the LH surge. The adaptive significance of this specialization remains to be determined.

Highlights

The propagation and survival of all species depends on reproduction
Using gene targeting in embryonic stem cells, we generated knock-in mice in which the endogenous exon 3 of Gnrhr was replaced by a modified exon 3 encoding the C-terminus of murine GnRHR fused in-frame with the intracellular cytosolic tail (Ctail) of the chicken GnRHR (Figure 199 figure supplement 1A-B)
Heterozygous mice (GnrhrCtail/+) were interbred to produce wild-type 100 (WT, Gnrhr+/+), heterozygous (GnrhrCtail/+), and homozygous (Ctail, GnrhrCtail/Ctail) animals, which were born at the expected Mendelian frequencies (Figure 1-figure supplement 1C)

Summary

Introduction

The propagation and survival of all species depends on reproduction. The process is controlled by hormones in the hypothalamic-pituitary-gonadal axis. The hypothalamic decapeptide gonadotropin-releasing hormone (GnRH) is the most important brain hormone regulating reproduction [1,2,3,4]. Disruption of GnRH synthesis, secretion, or action can delay or prevent puberty or cause infertility. GnRH acts via its receptor, GnRHR, in pituitary gonadotrope cells. GnRHR agonists and antagonists are used clinically in assisted reproductive technologies and to treat hormone-dependent diseases [2, 5,6,7]

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Results

Conclusion