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Endocrinology. 2014 Nov;155(11):4433-46. doi: 10.1210/en.2014-1304. Epub 2014 Aug 22.

KISS1R signals independently of Gαq/11 and triggers LH secretion via the β-arrestin pathway in the male mouse.

Author information

1
The Children's Health Research Institute (M.A., M.P., A.V.B.), London, Ontario, Canada; Lawson Health Research Institute (M.A., M.P., A.V.B.), London, Ontario, Canada; Departments of Obstetrics and Gynaecology (M.P., A.V.B.), Physiology and Pharmacology (M.A., M.B., A.V.B.), and Oncology (M.B.), The University of Western Ontario, London, Ontario, Canada N6C 2V5; Division of Endocrinology, Diabetes, and Hypertension (L.M., J.W., K.S., R.S.C., U.B.K.), Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115; Department of Biomedical Sciences (C.N., S.A.T.), Colorado State University, Fort Collins, Colorado 80523; and Department of Reproductive Medicine (C.A.G.-K., P.L.M.), Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093.

Abstract

Hypothalamic GnRH is the master regulator of the neuroendocrine reproductive axis, and its secretion is regulated by many factors. Among these is kisspeptin (Kp), a potent trigger of GnRH secretion. Kp signals via the Kp receptor (KISS1R), a Gαq/11-coupled 7-transmembrane-spanning receptor. Until this study, it was understood that KISS1R mediates GnRH secretion via the Gαq/11-coupled pathway in an ERK1/2-dependent manner. We recently demonstrated that KISS1R also signals independently of Gαq/11 via β-arrestin and that this pathway also mediates ERK1/2 activation. Because GnRH secretion is ERK1/2-dependent, we hypothesized that KISS1R regulates GnRH secretion via both the Gαq/11- and β-arrestin-coupled pathways. To test this hypothesis, we measured LH secretion, a surrogate marker of GnRH secretion, in mice lacking either β-arrestin-1 or β-arrestin-2. Results revealed that Kp-dependent LH secretion was significantly diminished relative to wild-type mice (P < .001), thus supporting that β-arrestin mediates Kp-induced GnRH secretion. Based on this, we hypothesized that Gαq/11-uncoupled KISS1R mutants, like L148S, will display Gαq/11-independent signaling. To test this hypothesis, L148S was expressed in HEK 293 cells. and results confirmed that, although strongly uncoupled from Gαq/11, L148S retained the ability to trigger significant Kp-dependent ERK1/2 phosphorylation (P < .05). Furthermore, using mouse embryonic fibroblasts lacking β-arrestin-1 and -2, we demonstrated that L148S-mediated ERK1/2 phosphorylation is β-arrestin-dependent. Overall, we conclude that KISS1R signals via Gαq/11 and β-arrestin to regulate GnRH secretion. This novel and important finding could explain why patients bearing some types of Gαq/11-uncoupled KISS1R mutants display partial gonadotropic deficiency and even a reversal of the condition, idiopathic hypogonadotropic hypogonadism.

PMID:
25147978
PMCID:
PMC4197989
DOI:
10.1210/en.2014-1304
[Indexed for MEDLINE]
Free PMC Article

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