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Functional Role, Structure, and Evolution of the Melanocortin‐4 Receptor
Author(s) -
SCHIÖTH HELGI B.,
LAGERSTRÖM MALIN C.,
WATANOBE HAJIME,
JONSSON LOGI,
VERGONI ANNA VALERIA,
RINGHOLM ANETA,
SKARPHEDINSSON JON O.,
SKULADOTTIR GUDRUN V.,
KLOVINS JANIS,
FREDRIKSSON ROBERT
Publication year - 2003
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2003.tb03164.x
Subject(s) - melanocortin receptor , receptor , medicine , endocrinology , biology , agonist , melanocortin , 5 ht5a receptor , melanocortin 4 receptor , g protein coupled receptor , leptin receptor , prolactin receptor , leptin , hormone , prolactin , obesity
A bstract : The melanocortin (MC)‐4 receptor participates in regulating body weight homeostasis. We demonstrated early that acute blockage of the MC‐4 receptor increases food intake and relieves anorexic conditions in rats. Our recent studies show that 4‐week chronic blockage of the MC‐4 receptor leads to robust increases in food intake and development of obesity, whereas stimulation of the receptor leads to anorexia. Interestingly, the food conversion ratio was clearly increased by MC‐4 receptor blockage, whereas it was decreased in agonist‐treated rats in a transient manner. Chronic infusion of an agonist caused a transient increase in oxygen consumption. Our studies also show that the MC‐4 receptor plays a role in luteinizing hormone and prolactin surges in female rats. The MC‐4 receptor has a role in mediating the effects of leptin on these surges. The phylogenetic relation of the MC‐4 receptor to other GPCRs in the human genome was determined. The three‐dimensional structure of the protein was studied by construction of a high‐affinity zinc binding site between the helices, using two histidine residues facing each other. We also cloned the MC‐4 receptor from evolutionary important species and showed by chromosomal mapping a conserved synteny between humans and zebrafish. The MC‐4 receptor has been remarkably conserved in structure and pharmacology for more than 400 million years, implying that the receptor participated in vital physiological functions early in vertebrate evolution.