Cloning and molecular characterization of the novel human melanin-concentrating hormone receptor MCH2.
Using a genomics-based approach for screening orphan G-protein-coupled receptors, we have identified and cloned a novel high-affinity, melanin-concentrating hormone (MCH) receptor. This receptor, named S643b, displays the greatest overall identity (32%) with the previously reported human SLC-1 receptor (MCH1) and to a lesser extent with the somatostatin receptor subtypes. The gene encoding the S643b receptor spans more than 23 kilobase pairs (kb) and was mapped, by radiation hybrid experiments, on chromosome 6q14.3-q15. Comparison of the S643b cDNA with human genomic sequence reveals that the 340-amino-acid receptor is encoded by five exons. Its tissue distribution, as determined by Northern blot and reverse transcription-polymerase chain reaction analysis, indicates that a 4-kb transcript is predominantly expressed in the brain. When expressed in Chinese hamster ovary (CHO) cells, the S643b receptor displays a strong, dose-dependent, transient elevation of intracellular calcium in response to MCH (EC(50) = 9.5 nM). During the present study, we isolated a splice variant, designated S643a, encoding for a receptor that was not activated by MCH in a cellular calcium mobilization assay. Comparative pharmacological studies using CHO cells stably expressing either SLC-1 or S643b receptors demonstrated that similar structural features of MCH are required to stimulate intracellular Ca(2+) mobilization at both receptors. The identification and localization of this new MCH receptor (MCH2) provides further insight into the physiological implication of MCH in modulating behavioral responses, including food intake.
Rodriguez
M
M
Institut de Recherches Servier, Division de Pharmacologie Moléculaire et Cellulaire, Croissy sur Seine, France.
Beauverger
P
P
Naime
I
I
Rique
H
H
Ouvry
C
C
Souchaud
S
S
Dromaint
S
S
Nagel
N
N
Suply
T
T
Audinot
V
V
Boutin
J A
JA
Galizzi
J P
JP
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D002896:Chromosomes, Human, Pair 6; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D011979:Receptors, Pituitary Hormone / Q000235:genetics* / Q000378:metabolism; D017481:Receptors, Somatostatin / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D018076:DNA, Complementary; C103263:MCHR1 protein, human; C431280:MCHR2 protein, human; D010455:Peptides; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D011979:Receptors, Pituitary Hormone; D017481:Receptors, Somatostatin