Melanin-concentrating hormone receptor 1 activates extracellular signal-regulated kinase and synergizes with G(s)-coupled pathways

• Published in: Endocrinology (Philadelphia) 2003-08, Vol.144 (8), p.3514
• Main Authors: Pissios, Pavlos, Trombly, Daniel J, Tzameli, Iphigenia, Maratos-Flier, Eleftheria
• Format: Article
• Language: English
• Subjects: Animals; Brain - enzymology; Cell Line; Colforsin - antagonists & inhibitors; Colforsin - pharmacology; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Drug Synergism; Embryo, Mammalian; Enzyme Activation - drug effects; Gene Expression; GTP-Binding Protein alpha Subunits, Gs - physiology; Humans; Hypothalamic Hormones - pharmacology; Isoproterenol - pharmacology; Kidney; Melanins - pharmacology; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases - metabolism; Pertussis Toxin - pharmacology; Phosphorylation; Pituitary Hormones - pharmacology; Protein Kinase C - metabolism; Rats; Receptors, Adrenergic, beta - physiology; Receptors, Pituitary Hormone - genetics; Receptors, Pituitary Hormone - physiology; Signal Transduction; src-Family Kinases - metabolism; Transfection; Type C Phospholipases - metabolism
• ISSN: 0013-7227
• DOI: 10.1210/en.2002-0004

Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide that plays a key role in energy homeostasis. Like many neuropeptides, it signals through two G protein-coupled receptors. MCH receptor 1 (MCHR1) is the sole receptor expressed in rodents and couples to G(i) and G(q) proteins. Little is known about the intracellular pathways engaged by MCH and its receptor. Using HEK293 cells stably expressing MCHR1, we demonstrate that MCH, acting through MCHR1, antagonizes the action of forskolin, an adenylate cyclase activator that increases intracellular levels of cAMP. MCH also inhibits cAMP induction by the G(s)-coupled beta-adrenergic receptor. Activation of either the G(i)- or G(s)-dependent pathway typically results in ERK phosphorylation in HEK293 cells. In contrast to opposing actions on cAMP synthesis, simultaneous MCH and forskolin treatment results in synergistic activation of ERK. This synergy proceeds through pertussis toxin-independent pathways and requires several enzymatic activities such as protein kinase A, protein kinase C, phospholipase C, and Src kinase. Finally, we provide evidence that such positive interactions are not limited to cell lines but can also be observed in the brain.