Two Naturally Occurring Mutations in the Type 1 Melanin-Concentrating Hormone Receptor Abolish Agonist-Induced Signaling
| Autor: | Jonathan C. Schroeder, Jean-Philippe Fortin, Scott E. Schaus, Jennifer M. Goss, Carmit Goldstein, Alan S. Kopin, Martin Beinborn |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Agonist
medicine.medical_specialty medicine.drug_class Mutant Mutation Missense Gene Expression Biology Transfection Polymorphism Single Nucleotide Metabolism Transport and Pharmacogenomics Piperidines Thinness Genes Reporter Internal medicine medicine Humans Receptors Somatostatin Receptor Pharmacology Melanins Hypothalamic Hormones Dose-Response Relationship Drug HEK 293 cells Antagonist Wild type Recombinant Proteins Melanin-concentrating hormone receptor Pituitary Hormones Endocrinology HEK293 Cells Pyrimidines Molecular Medicine Hormone Signal Transduction |
| Popis: | The melanin-concentrating hormone (MCH) receptor type 1 (MCHR1) is a seven-transmembrane domain protein that modulates orexigenic activity of MCH, the corresponding endogenous peptide agonist. MCH antagonists are being explored as a potential treatment for obesity. In the current study, we examined the pharmacological impact of 11 naturally occurring mutations in the human MCHR1. Wild-type and mutant receptors were transiently expressed in human embryonic kidney 293 cells. MCHR1-mediated, Gα(i)-dependent signaling was monitored by using luciferase reporter gene assays. Two mutants, R210H and P377S, failed to respond to MCH. Five other variants showed significant alterations in MCH efficacy, ranging from 44 to 142% of the wild-type value. At each of the MCH-responsive mutants, agonist potency and inhibition by (S)-methyl 3-((3-(4-(3-acetamidophenyl)piperidin-1-yl)propyl)carbamoyl)-4-(3,4-difluorophenyl)-6-(methoxymethyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (SNAP-7941), an established MCHR1 small-molecule antagonist, were similar to wild type. To explore the basis for inactivity of the R210H and P377S mutants, we examined expression levels of these receptors. Assessment by enzyme-linked immunosorbent assay revealed that cell surface expression of both nonfunctional receptors was comparable with wild type. Overnight treatment with SNAP-7941, followed by washout of antagonist, enhanced MCH induced signaling by the wild-type receptor and restored MCH responsiveness of the P377S but not the R210H variant. It is of note that the two loss-of-function mutants were identified in markedly underweight individuals, raising the possibility that a lean phenotype may be linked to deficient MCHR1 signaling. Formal association studies with larger cohorts are needed to explore the extent to which signaling-deficient MCHR1 variants influence the maintenance of body weight. |
| Databáze: | OpenAIRE |
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