Heifers express G-protein coupled receptor 61 in anterior pituitary gonadotrophs in stage-dependent manner

• Published in: Animal reproduction science 2017-06, Vol.181, p.93-102
• Main Authors: Pandey, Kiran, Kereilwe, Onalenna, Borromeo, Vitaliano, Kadokawa, Hiroya
• Format: Article
• Language: English
• Subjects: Animals; Cattle; Estrous Cycle - physiology; Female; Follicle stimulating hormone; Gene Expression Regulation - physiology; Gonadotropin-releasing hormone receptor; Lipid raft; Luteinizing hormone; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Orphan receptor; Pituitary Gland, Anterior - metabolism; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - metabolism; Receptors, LHRH - genetics; Receptors, LHRH - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Ruminant
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2017.03.020

•Majority of GPR61 colocalized with GnRHR in the plasma membrane of gonadotrophs.•GPR61 levels were lowest during early luteal phase of the reproductive cycle.•GPR61 gene 5′-flanking region contains estrogen/progesterone-type response elements.•GPR61 may mediate reproductive stage-specific signaling in bovine anterior pituitary. Gonadotropin-releasing hormone receptors (GnRHRs) colocalize with insulin and glucocorticoid receptors in lipid rafts of the gonadotroph plasma membrane, where they facilitate downstream signaling. We recently found that orphan G-protein-coupled receptor (GPR)61 is expressed in the anterior pituitary (AP) of heifers, leading us to speculate that GPR61 colocalizes with GnRHR in the plasma membrane of gonadotroph and is expressed at specific times of the reproductive cycle. To test this hypothesis, we examined the coexpression of GnRHR, GPR61, and either luteinizing hormone (LH) β subunit or follicle-stimulating hormone (FSH) β subunit in AP tissue and cultured AP cells by immunofluorescence microscopy. GPR61 was detected in gonadotrophs, with a majority of them being colocalized with GnRHR and the remainder present at other parts of the cell surface or in the cytoplasm. We obtained a strong positive overlap coefficient (0.71±0.01) between GPR61 and GnRHR on the cell-surface of cultured GnRHR-positive AP cells. Real-time PCR and western blot analyses found that expression was lower (P