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Mol Cell Endocrinol. 2013 Dec 5;381(1-2):8-15. doi: 10.1016/j.mce.2013.07.009. Epub 2013 Jul 20.

Mutual interaction of kisspeptin, estrogen and bone morphogenetic protein-4 activity in GnRH regulation by GT1-7 cells.

Author information

1
Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan; Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.

Abstract

Reproduction is integrated by interaction of neural and hormonal signals converging on hypothalamic neurons for controlling gonadotropin-releasing hormone (GnRH). Kisspeptin, the peptide product of the kiss1 gene and the endogenous agonist for the GRP54 receptor, plays a key role in the regulation of GnRH secretion. In the present study, we investigated the interaction between kisspeptin, estrogen and BMPs in the regulation of GnRH production by using mouse hypothalamic GT1-7 cells. Treatment with kisspeptin increased GnRH mRNA expression and GnRH protein production in a concentration-dependent manner. The expression levels of kiss1 and GPR54 were not changed by kisspeptin stimulation. Kisspeptin induction of GnRH was suppressed by co-treatment with BMPs, with BMP-4 action being the most potent for suppressing the kisspeptin effect. The expression of kisspeptin receptor, GPR54, was suppressed by BMPs, and this effect was reversed in the presence of kisspeptin. It was also revealed that BMP-induced Smad1/5/8 phosphorylation and Id-1 expression were suppressed and inhibitory Smad6/7 was induced by kisspeptin. In addition, estrogen induced GPR54 expression, while kisspeptin increased the expression levels of ERα and ERβ, suggesting that the actions of estrogen and kisspeptin are mutually enhanced in GT1-7 cells. Moreover, kisspeptin stimulated MAPKs and AKT signaling, and ERK signaling was functionally involved in the kisspeptin-induced GnRH expression. BMP-4 was found to suppress kisspeptin-induced GnRH expression by reducing ERK signaling activity. Collectively, the results indicate that the axis of kisspeptin-induced GnRH production is bi-directionally controlled, being augmented by an interaction between ERα/β and GPR54 signaling and suppressed by BMP-4 action in GT1-7 neuron cells.

KEYWORDS:

ALK; ARC; AVPV; ActRІІ; BMP; BMP type ІІ receptor; BMPRІІ; ER; ERK; Estradiol; FSH; G-protein-coupled receptor 54; GPR54; GnIH; GnRH; JNK; Kisspeptin; LH; MAPK; activin receptor-like kinase; activin type ІІ receptor; anteroventral periventricular nucleus; arcuate nucleus; bone morphogenetic protein; c-Jun NH(2)-terminal kinase; estrogen receptor; extracellular signal-regulated kinase; follicle-stimulating hormone; gonadotropin-inhibitory hormone; gonadotropin-releasing hormone; luteinizing hormone; mitogen-activated protein kinase

PMID:
23880664
PMCID:
PMC4079587
DOI:
10.1016/j.mce.2013.07.009
[Indexed for MEDLINE]
Free PMC Article

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