title: Melanocortin-3 receptor activates MAP kinase via PI3 kinase.
abstract: HEK 293 cells stably expressing human melanocortin-3 receptor (MC3R) were exposed to melanocortin receptor agonist, NDP-MSH (10(-)(10)-10(-)(6) M). ERK1/2 was phosphorylated in a dose-dependent manner with an EC(50) of 3.3+/-1.5 x 10(-)(9) M, similar to the IC(50) of NDP-MSH binding to the MC3R. ERK1/2 phosphorylation was blocked by the melanocortin receptor antagonists SHU9119. NDP-MSH-induced ERK1/2 phosphorylation was sensitive to pertussis toxin and the PI3K inhibitor, wortmannin. Rp-cAMPS, BAPTA-AM and Myr-PKC did not inhibit the NDP-MSH-induced ERK1/2 phosphorylation. NDP-MSH stimulated cellular proliferation in a dose-dependent manner with a similar EC(50) to ERK1/2 phosphorylation, 2.1+/-0.6 x 10(-)(9) M. Cellular proliferation was blocked by AGRP (86-132) and by the MEK inhibitor, PD98059. The NDP-MSH did not inhibit serum deprivation-induced apoptosis. MC3R activation induces ERK1/2 phosphorylation via PI3K and this pathway is involved in cellular proliferation in HEK cells expressing MC3R.
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Biaoxin
authors.initials: B
authors.lastname: Chai
authors.forename: Ji-Yao
authors.initials: JY
authors.lastname: Li
authors.forename: Weizhen
authors.initials: W
authors.lastname: Zhang
authors.forename: John B
authors.initials: JB
authors.lastname: Ammori
authors.forename: Michael W
authors.initials: MW
authors.lastname: Mulholland
mesh_terms: D054369:Agouti-Related Protein; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D044104:Receptor, Melanocortin, Type 3 / Q000037:antagonists & inhibitors / Q000502:physiology*; D000521:alpha-MSH / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D054369:Agouti-Related Protein; D005419:Flavonoids; D010446:Peptide Fragments; D044104:Receptor, Melanocortin, Type 3; C430443:agouti-related protein (86-132), human; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-; D019869:Phosphatidylinositol 3-Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one