KISS1R Signals Independently of Gαq/11 and Triggers LH Secretion via the β-Arrestin Pathway in the Male Mouse

M Ahow, L Min, M Pampillo, C Nash, J Wen… - …, 2014 - academic.oup.com
M Ahow, L Min, M Pampillo, C Nash, J Wen, K Soltis, RS Carroll, CA Glidewell-Kenney…
Endocrinology, 2014academic.oup.com
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 …
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.
Oxford University Press