title: GPR54 regulates ERK1/2 activity and hypothalamic gene expression in a Gα(q/11) and β-arrestin-dependent manner.
abstract: G protein-coupled receptor 54 (GPR54) is a G(q/11)-coupled 7 transmembrane-spanning receptor (7TMR). Activation of GPR54 by kisspeptin (Kp) stimulates PIP(2) hydrolysis, Ca(2+) mobilization and ERK1/2 MAPK phosphorylation. Kp and GPR54 are established regulators of the hypothalamic-pituitary-gonadal (HPG) axis and loss-of-function mutations in GPR54 are associated with an absence of puberty and hypogonadotropic hypogonadism, thus defining an important role of the Kp/GPR54 signaling system in reproductive function. Given the tremendous physiological and clinical importance of the Kp/GPR54 signaling system, we explored the contributions of the GPR54-coupled G(q/11) and β-arrestin pathways on the activation of a major downstream signaling molecule, ERK, using G(q/11) and β-arrestin knockout mouse embryonic fibroblasts. Our study revealed that GPR54 employs the G(q/11) and β-arrestin-2 pathways in a co-dependent and temporally overlapping manner to positively regulate ERK activity and pERK nuclear localization. We also show that while β-arrestin-2 potentiates GPR54 signaling to ERK, β-arrestin-1 inhibits it. Our data also revealed that diminished β-arrestin-1 and -2 expression in the GT1-7 GnRH hypothalamic neuronal cell line triggered distinct patterns of gene expression following Kp-10 treatment. Thus, β-arrestin-1 and -2 also regulate distinct downstream responses in gene expression. Finally, we showed that GPR54, when uncoupled from the G(q/11) pathway, as is the case for several naturally occurring GPR54 mutants associated with hypogonadotropic hypogonadism, continues to regulate gene expression in a G protein-independent manner. These new and exciting findings add significantly to our mechanistic understanding of how this important receptor signals intracellularly in response to kisspeptin stimulation.
authors.affiliation: The Children's Health Research Institute, London, Ontario, Canada.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Szereszewski
authors.forename: Macarena
authors.initials: M
authors.lastname: Pampillo
authors.forename: Maryse R
authors.initials: MR
authors.lastname: Ahow
authors.forename: Stefan
authors.initials: S
authors.lastname: Offermanns
authors.forename: Moshmi
authors.initials: M
authors.lastname: Bhattacharya
authors.forename: Andy V
authors.initials: AV
authors.lastname: Babwah
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D000074502:Receptors, Kisspeptin-1; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
chemical_list: C000605255:Arrb1 protein, mouse; C000605258:Arrb2 protein, mouse; D019390:Arrestins; C492248:Kiss1r protein, mouse; D043562:Receptors, G-Protein-Coupled; D000074502:Receptors, Kisspeptin-1; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D043802:GTP-Binding Protein alpha Subunits, Gq-G11