Mutational Analysis of the Genes Encoding RFAmide‐Related Peptide‐3, the Human Orthologue of Gonadotrophin‐Inhibitory Hormone, and its Receptor (GPR147) in Patients with Gonadotrophin‐Releasing Hormone‐Dependent Pubertal Disorders

Abstract

RFamide-related peptide-3 (RFRP-3), the orthologue of avian gonadotrophin-inhibitory hormone, and its receptor GPR147 have been recently identified in the human hypothalamus, and their roles in the regulation of reproductive axis has been studied. The present study aimed to investigate whether the presence of variants in the genes encoding human RFRP-3 (NPVF gene) and its receptor, GPR147 (NPFFR1 gene), is associated with the occurrence of gonadotrophin-releasing hormone-dependent pubertal disorders. Seventy-eight patients with idiopathic central precocious puberty (CPP) and 51 with normosmic isolated hypogonadotrophic hypogonadism (nIHH) were investigated. Fifty healthy subjects comprised the control group. The coding sequences of the NPVF and NPFFR1 genes were amplified and sequenced. Odds ratios (OR) were used to estimate the likelihood of CPP or nIHH in the presence of the described polymorphisms. All such polymorphisms have already been registered in the National Center for Biotechnology Information database. A three-nucleotide in frame deletion was identified in the NPVF gene (p.I71_K72), with a smaller proportion in the CPP (5%) compared to the nIHH (15%) group (P = 0.06). This results in the deletion of the isoleucine at position 71, adjacent to lysine at an endoproteolytic cleavage site of the precursor peptide. This polymorphism was associated with a lower risk of CPP (OR = 0.33; 95% confidence interval = 0.08-0.88); interestingly, only two men with nIHH were homozygotes for this variant. A total of five missense polymorphisms were found in the NPFFR1 gene, which encodes GPR147, with similar frequencies among groups and no association with pubertal timing. Our data suggest that RFRP-3/GPR147 may play secondary, modulatory roles on the regulation of pubertal development; a restraining modulatory effect of the NPVF p.I71_K72 variant on the activation of the gonadotrophic axis cannot be ruled out and deserves further investigation.

Intracerebroventricular injection of RFRP-3 delays puberty onset and stimulates growth hormone secretion in female rats

“…Pubertal analyses of null mice evidenced that GPR147 KO males, but not females, displayed constitutively elevated LH levels before and during puberty, whereas pubertal progression was not apparently altered by the congenital lack of GPR147 in either sex [35]. In accordance with this suggestion, a human genetics study revealed that the presence of variants in the genes encoding RFRP-3 and GPR147 is not associated with the occurrence of GnRH-pubertal disorders [34]. However, a 2015 study, by Semaan and Kauffman, showed a decrease in RFRP-3 expression in the hypothalamic dorsomedial nucleus during the prepubertal stage in mice [37].…”

“…Our data show that ICV injection of RFRP-3 significantly delay the timing of puberty onset, characterized by delayed vaginal opening time and uterine development; it also reduce the serum levels of LH and E2. Recently, several findings suggested that endogenous RFRP-3 signaling may not be necessary for the timing of puberty [34, 35]. Pubertal analyses of null mice evidenced that GPR147 KO males, but not females, displayed constitutively elevated LH levels before and during puberty, whereas pubertal progression was not apparently altered by the congenital lack of GPR147 in either sex [35].…”

“…There is little evidence showing that RFRP-3 plays a definite role in the timing of pubertal onset in young mammals. A study conducted in 2014 suggested that the presence of variants in the genes encoding human RFRP-3 and GPR147 is not associated with the occurrence of GnRH-dependent pubertal disorders [34]. The pubertal timing was not altered in GPR147 (NPFF1R) knockout (KO) mice [35].…”

Molecular, cellular, morphological, physiological and behavioral aspects of gonadotropin-inhibitory hormone

“…This three-nucleotide in frame deletion resulted in the absence of the isoleucine at position 71, adjacent to lysine at an endoproteolytic cleavage site of GnIH precursor polypeptide (Ubuka et al, 2009c). This deletion of the isoleucine at position 71 was associated with a lower risk of CPP, and the two men with nIHH were both homozygotes for this variant (Lima et al, 2014).…”

“…There were significant associations between polymorphic loci and age at first egg, body weight at first egg and egg production in 300 days (Hu et al, 2015). Lima et al (2014) reported that there is a three-nucleotide in frame deletion in the human GnIH precursor gene (p.I71_K72), with a smaller proportion in the idiopathic central precocious puberty (CPP) (5%) compared to the normosmic isolated hypogonadotrophic hypogonadism (nIHH) (15%) group. This three-nucleotide in frame deletion resulted in the absence of the isoleucine at position 71, adjacent to lysine at an endoproteolytic cleavage site of GnIH precursor polypeptide (Ubuka et al, 2009c).…”