RESUMEN
Melanin-concentrating hormone receptor 1 (MCH-R1) is a G-protein-coupled receptor (GPCR) and a target for the development of therapeutics for obesity. The structure-based development of MCH-R1 and other GPCR antagonists is hampered by the lack of an available experimentally determined atomic structure. A ligand-steered homology modeling approach has been developed (where information about existing ligands is used explicitly to shape and optimize the binding site) followed by docking-based virtual screening. Top scoring compounds identified virtually were tested experimentally in an MCH-R1 competitive binding assay, and six novel chemotypes as low micromolar affinity antagonist "hits" were identified. This success rate is more than a 10-fold improvement over random high-throughput screening, which supports our ligand-steered method. Clearly, the ligand-steered homology modeling method reduces the uncertainty of structure modeling for difficult targets like GPCRs.
Asunto(s)
Ligandos , Modelos Moleculares , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Receptores de la Hormona Hipofisaria/química , Receptores de Somatostatina/antagonistas & inhibidores , Receptores de Somatostatina/química , Animales , Sitios de Unión , Unión Competitiva , Células CHO , Bovinos , Cricetinae , Cricetulus , Bases de Datos Factuales , Humanos , Receptores de la Hormona Hipofisaria/metabolismo , Receptores de Somatostatina/metabolismo , Rodopsina/química , Homología de Secuencia de Aminoácido , Procesos Estocásticos , Relación Estructura-Actividad , TermodinámicaRESUMEN
Vitiligo is a common depigmenting disorder resulting from the loss of melanocytes in the skin. The pathogenesis of the disease remains obscure, although autoimmune mechanisms are thought to be involved. Indeed, autoantibodies and autoreactive T lymphocytes that target melanocytes have been reported in some vitiligo patients. The objective of this study was to identify pigment cell antigens that are recognized by autoantibodies in vitiligo. Using IgG from vitiligo patients to screen a melanocyte cDNA phage-display library, we identified the melanin-concentrating hormone receptor 1 (MCHR1) as a novel autoantigen related to this disorder. Immunoreactivity against the receptor was demonstrated in vitiligo patient sera by using radiobinding assays. Among sera from healthy controls and from patients with autoimmune disease, none exhibited immunoreactivity to MCHR1, indicating a high disease specificity for Ab's against the receptor. Inhibition of MCH binding to its receptor by IgG from vitiligo patients was also shown.
Asunto(s)
Autoanticuerpos/inmunología , Autoantígenos/inmunología , Receptores de la Hormona Hipofisaria/inmunología , Vitíligo/inmunología , Absorción , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Autoanticuerpos/sangre , ADN Complementario , Femenino , Ingeniería Genética , Humanos , Inmunoglobulina G/inmunología , Masculino , Persona de Mediana Edad , Biblioteca de Péptidos , Radioinmunoensayo , Vitíligo/sangreRESUMEN
Melanin-concentrating hormone (MCH) is a cyclic, nonadecapeptide expressed in the CNS of all vertebrates that regulates feeding behavior and energy homeostasis via interaction with the central melanocortin system. Regulation of this interaction results in modulation of food intake and body weight gain, demonstrating significant therapeutic potential for the treatment of obesity. The MCH-1 receptor (MCH-R1) has been identified as a key target in MCH regulation, as small molecule antagonists of MCH-R1 have demonstrated activity in vivo. Herein, we document our research in a bicyclo[3.1.0]hexyl urea series with particular emphasis on structure-activity relationships and optimization of receptor occupancy, measured both in vitro and via an ex vivo binding assay following an oral dosing regimen. Several compounds have been tested in vivo and exhibit oral efficacy in relevant acute rodent feeding models. In particular, 24u has proven efficacious in chronic rodent models of obesity, showing a statistically significant reduction in food intake and body weight over a 28 day study.
Asunto(s)
Fármacos Antiobesidad/síntesis química , Compuestos de Fenilurea/síntesis química , Piperazinas/síntesis química , Receptores de Somatostatina/antagonistas & inhibidores , Urea/análogos & derivados , Urea/síntesis química , Administración Oral , Animales , Fármacos Antiobesidad/farmacología , Disponibilidad Biológica , Peso Corporal/efectos de los fármacos , Encéfalo/metabolismo , Células CHO , Cricetinae , Cricetulus , Ingestión de Alimentos/efectos de los fármacos , Semivida , Masculino , Obesidad/tratamiento farmacológico , Compuestos de Fenilurea/farmacología , Piperazinas/farmacología , Ensayo de Unión Radioligante , Ratas , Receptores de Somatostatina/metabolismo , Relación Estructura-Actividad , Distribución Tisular , Urea/farmacologíaRESUMEN
Melanin concentrating hormone (MCH) is a cyclic neuropeptide expressed in the lateral hypothalamus that plays an important role in energy homeostasis. To investigate the pharmacological consequences of inhibiting MCH signaling in murine obesity models, we examined the effect of acute and chronic administration of a selective MCH1 receptor antagonist (SCH-A) in diet-induced obese (DIO) and Lep(ob/ob) mice. Oral administration of SCH-A for 5 consecutive days (30 mg/kg q.d.) produced hypophagia, a loss of body weight and adiposity, and decreased plasma leptin levels in DIO mice, and hypophagia and reduced weight gain in Lep(ob/ob) mice. Chronic administration of SCH-A to DIO mice decreased food intake, body weight and adiposity, and plasma leptin and free fatty acids. These effects were accompanied by increases in several hypothalamic neuropeptides. Acute administration of SCH-A (30 mg/kg) prevented the decrease in energy expenditure associated with food restriction. These results indicate that MCH1 receptor antagonists may be effective in the treatment of obesity.
Asunto(s)
Ingestión de Alimentos/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Nitrilos/farmacología , Obesidad/fisiopatología , Piperazinas/farmacología , Receptores de Somatostatina/antagonistas & inhibidores , Urea/análogos & derivados , Tejido Adiposo/efectos de los fármacos , Administración Oral , Animales , Unión Competitiva , Peso Corporal/efectos de los fármacos , Encéfalo/metabolismo , Células CHO , Cricetinae , Cricetulus , Grasas de la Dieta/administración & dosificación , Relación Dosis-Respuesta a Droga , Ácidos Grasos no Esterificados/sangre , Femenino , Galanina/genética , Expresión Génica/efectos de los fármacos , Homeostasis/efectos de los fármacos , Hormonas Hipotalámicas/genética , Hipotálamo/efectos de los fármacos , Hipotálamo/metabolismo , Insulina/sangre , Péptidos y Proteínas de Señalización Intracelular/genética , Radioisótopos de Yodo , Leptina/sangre , Masculino , Melaninas/genética , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Neuropéptido Y/genética , Neuropéptidos/genética , Nitrilos/administración & dosificación , Obesidad/etiología , Oligopéptidos/metabolismo , Receptores de Orexina , Orexinas , Piperazinas/administración & dosificación , Hormonas Hipofisarias/genética , Unión Proteica , Receptores Acoplados a Proteínas G , Receptores de Neuropéptido , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Triglicéridos/sangre , Urea/administración & dosificación , Urea/farmacologíaRESUMEN
Melanin concentrating hormone (MCH) is involved in regulation of food intake and energy homeostasis. Antagonists of the MCH receptor are expected to affect food intake and weight gain, making MCH-R1 an attractive target for obesity treatment. Herein, we report the discovery of a novel, orally active series of MCH-R1 antagonists that exhibit in vivo efficacy in rodent obesity models.
Asunto(s)
Fármacos Antiobesidad/síntesis química , Compuestos Bicíclicos con Puentes/síntesis química , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Receptores de Somatostatina/antagonistas & inhibidores , Urea/análogos & derivados , Urea/síntesis química , Administración Oral , Animales , Fármacos Antiobesidad/química , Fármacos Antiobesidad/farmacología , Disponibilidad Biológica , Encéfalo/metabolismo , Compuestos Bicíclicos con Puentes/química , Compuestos Bicíclicos con Puentes/farmacología , Cicloheptanos/síntesis química , Cicloheptanos/química , Cicloheptanos/farmacología , Ciclohexanos/síntesis química , Ciclohexanos/química , Ciclohexanos/farmacología , Ingestión de Alimentos/efectos de los fármacos , Ratones , Obesidad/tratamiento farmacológico , Ratas , Urea/química , Urea/farmacologíaRESUMEN
Vorapaxar is a novel protease-activated receptor-1 (PAR1) antagonist recently approved for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction or with peripheral arterial disease. The present study provides a comprehensive in vitro pharmacological characterization of vorapaxar interaction with the PAR1 receptor on human platelets. Similar studies were performed with a metabolite of vorapaxar (M20). Vorapaxar and M20 were competitive PAR1 antagonists that demonstrated concentration-dependent, saturable, specific, and slowly reversible binding to the receptor present on intact human platelets. The affinities of vorapaxar and M20 for the PAR1 receptor were in the low nanomolar range, as determined by saturation-, kinetic- and competitive binding studies. The calculated Kd and Ki values for vorapaxar increased in the presence of plasma, indicating a decrease in the free fraction available for binding to the PAR1 receptor on human platelets. Vorapaxar was also evaluated in functional assays using thrombin or a PAR1 agonist peptide (SFLLRN). Vorapaxar and M20 completely blocked thrombin-stimulated PAR1/ß-arrestin association in recombinant cells and abolished thrombin-stimulated calcium influx in washed human platelets and vascular smooth muscle cells. Moreover, vorapaxar and M20 inhibited PAR1 agonist peptide-mediated platelet aggregation in human platelet rich plasma with a steep concentration response relationship. Vorapaxar exhibited high selectivity for inhibition of PAR1 over other platelet GPCRs. In conclusion, vorapaxar is a potent PAR1 antagonist exhibiting saturable, reversible, selective binding with slow off-rate kinetics and effectively inhibits thrombin's PAR1-mediated actions on human platelets.
Asunto(s)
Plaquetas/efectos de los fármacos , Lactonas/farmacología , Piridinas/farmacología , Receptor PAR-1/antagonistas & inhibidores , Arrestinas/metabolismo , Unión Competitiva , Plaquetas/metabolismo , Plaquetas/fisiología , Proteínas Sanguíneas/metabolismo , Calcio/metabolismo , Humanos , Cinética , Lactonas/metabolismo , Agregación Plaquetaria/efectos de los fármacos , Piridinas/metabolismo , Receptor PAR-1/metabolismo , Especificidad por Sustrato , beta-ArrestinasRESUMEN
Rhesus monkey MCH-R1 and MCH-R2 receptors were cloned. Amino acid homology is 98.8% between monkey and human MCH-R1, while monkey and human MCH-R2 are 98% homologous. Binding and intracellular signaling characteristics of the monkey receptors were compared with the human homologues. The results demonstrate that MCH binds to the monkey MCH-R1 receptor with a K(d) of 6.5 nM and monkey MCH-R2 with a K(d) of 2.2 nM similar to K(d) values for human MCH-R1 and MCH-R2. Additionally, monkey MCH-R1 couples through G(i)/G(o) and G(q)-type G proteins similar to human MCH-R1 whereas monkey and human MCH-R2 utilize the G(q) signaling pathway.
Asunto(s)
Receptores de la Hormona Hipofisaria/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Células CHO , Calcio/metabolismo , Cricetinae , AMP Cíclico/metabolismo , Humanos , Hormonas Hipotalámicas/metabolismo , Macaca mulatta , Melaninas/metabolismo , Datos de Secuencia Molecular , Hormonas Hipofisarias/metabolismo , Reacción en Cadena de la Polimerasa , Receptores Acoplados a Proteínas G , Receptores de la Hormona Hipofisaria/metabolismo , Alineación de SecuenciaRESUMEN
Neuropeptide Y (NPY), 36-amino acid amidated peptide expressed in central and peripheral neurons, regulates a variety of physiological activities, including food intake, energy expenditure, vasoconstriction, anxiolysis, nociception and ethanol consumption. NPY binds to a family of G-protein coupled receptors whose activation results in inhibition of adenylyl cyclase activity. To more fully characterize the signal transduction pathways utilized by the NPY receptor subtypes, the pathways leading to phosphorylation of the extracellular signal regulated protein kinases 1 and 2 (ERK) have been compared in CHO cells expressing each of the four cloned human NPY receptor subtypes, Y(1), Y(2), Y(4) and Y(5). NPY Y(1), Y(2), Y(4) and Y(5) receptor-mediated ERK phosphorylation was blocked by pertussis toxin (PTX) exposure, indicating that all four receptors are coupled to inhibitory G(i/o) proteins. Exposure to the protein kinase C (PKC) inhibitor GF109203X diminished Y(1), Y(2) and Y(4) receptor-mediated ERK phosphorylation but completely blocked Y(5) receptor-mediated ERK phosphorylation. Additionally, Y(5) receptor-mediated ERK phosphorylation was inhibited by the phosphatidylinositol 3-kinase inhibitors LY294002 and wortmannin to a greater extent than was Y(1)-mediated ERK phosphorylation. These results demonstrate that in CHO cells, the Y(5) receptor and the Y(1), Y(2) and Y(4) receptors utilize different pathways to activate ERK.
Asunto(s)
Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Neuropéptido Y/farmacología , Polipéptido Pancreático/farmacología , Receptores de Neuropéptido Y/clasificación , Receptores de Neuropéptido Y/metabolismo , Toxina de Adenilato Ciclasa , Androstadienos/farmacología , Animales , Células CHO , Cromonas/farmacología , Clonación Molecular , Cricetinae , AMP Cíclico/metabolismo , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Humanos , Indoles/farmacología , Maleimidas/farmacología , Morfolinas/farmacología , Toxina del Pertussis , Fosforilación/efectos de los fármacos , Isoformas de Proteínas/metabolismo , Ratas , Factores de Virulencia de Bordetella/farmacología , WortmaninaRESUMEN
Ezetimibe is the first in class 2-azetidinone that decreases plasma cholesterol by blocking intestinal cholesterol absorption. Ezetimibe effectively reduces plasma cholesterol in several species including human, monkey, dog, hamster, rat, and mouse, but the potency ranges widely. One potential factor responsible for this variation in responsiveness is diversity in ezetimibe metabolism. After oral administration, ezetimibe is glucuronidated. Both ezetimibe and the glucuronide lower plasma cholesterol; however, the glucuronide exhibits greater potency. Recent identification of Niemann-Pick C1 Like-1 (NPC1L1) as the molecular target of ezetimibe enables direct binding studies to be performed. Here, we report the cloning of NPC1L1 derived from multiple species and assess amino acid sequence homology among human, monkey, dog, hamster, rat, and mouse. The rank order of affinity of glucuronidated ezetimibe for NPC1L1 in each species correlates with the rank order of in vivo activity with monkey > dog > hamster and rat >> mouse. Ezetimibe analogs that bind to NPC1L1 exhibit in vivo cholesterol-lowering activity, whereas compounds that do not bind NPC1L1 are inactive. Specific structural components of ezetimibe are identified as critical for binding to NPC1L1. The results demonstrate that small variations in ezetimibe structure or in NPC1L1 amino acid sequence can profoundly influence ezetimibe/NPC1L1 interaction and consequently in vivo activity. The results demonstrate that the ability of compounds to bind to NPC1L1 is the major determinant of in vivo responsiveness.
Asunto(s)
Azetidinas/farmacología , Azetidinas/farmacocinética , Proteínas de la Membrana/fisiología , Secuencia de Aminoácidos , Animales , Anticolesterolemiantes/farmacología , Sitios de Unión , Células Cultivadas , Colesterol/metabolismo , Clonación Molecular , ADN Complementario/genética , Ezetimiba , Humanos , Absorción Intestinal , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Proteínas de Transporte de Membrana , Modelos Moleculares , Datos de Secuencia Molecular , Enfermedades de Niemann-Pick , Conformación Proteica , RatasRESUMEN
To address the hERG liability of MCHR1 antagonists such as 1 and 2, new analogs such as 4 and 5 that incorporated a polar heteroaryl group were designed and synthesized. Biological evaluation confirmed that these new analogs retained MCH R1 activity with greatly attenuated hERG liabilities as indicated in the Rb efflux assay.
Asunto(s)
Química Farmacéutica/métodos , Heptanos/química , Hexanos/química , Receptores de Somatostatina/antagonistas & inhibidores , Animales , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Peces , Humanos , Cinética , Ratones , Modelos Químicos , Estructura Molecular , Obesidad/tratamiento farmacológicoRESUMEN
To improve the ex vivo potency of MCH inhibitor 1a and to address its hERG liability, a structure-activity study was carried out, focusing on three regions of the lead structure. Introduction of new side chains with basic nitrogen improved in vitro and ex vivo bindings. Many potent compounds with K(i)<10nM were discovered (compounds 6a-j) and several compounds (14-17) had excellent ex vivo binding at 6h and 24h. Attenuating the basicity of nitrogen on the side chain, and in particular, introduction of a polar group such as aminomethyl on the distal phenyl ring significantly lowered the hERG activity. Further replacement of the distal phenyl group with heteroaryl groups in the cyclohexene series provided compounds such as 28l with excellent ex vivo activity with much reduced hERG liability.
Asunto(s)
Cicloheptanos/química , Cicloheptanos/farmacocinética , Proteínas de Unión al ADN/metabolismo , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Transactivadores/metabolismo , Animales , Ratones , Estructura Molecular , Receptores de la Hormona Hipofisaria/metabolismo , Relación Estructura-Actividad , Regulador Transcripcional ERGRESUMEN
A series of novel aminobenzimidazoles was prepared and evaluated for h-MCH-R1 antagonist properties. Most of the compounds showed excellent h-MCH-R1 binding affinity as well as mouse ex vivo binding. Compounds 9 and 18 were active in mouse DIO studies at 30mpk.
Asunto(s)
Fármacos Antiobesidad/farmacología , Bencimidazoles/farmacología , Bencimidazoles/uso terapéutico , Enfermedades Metabólicas/tratamiento farmacológico , Receptores de Somatostatina/antagonistas & inhibidores , Animales , Fármacos Antiobesidad/química , Bencimidazoles/química , Unión Competitiva/efectos de los fármacos , Dieta , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos , Ingestión de Alimentos/efectos de los fármacos , Humanos , Ratones , Ratones Obesos , Conformación Molecular , Obesidad/tratamiento farmacológico , Ratas , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Isosteric replacement of the urea group of lead compound 1 led to novel substituted piperidine phenylamide analogues. SAR on the electron-induced effects of various linkers as well as substituents on the phenyl rings and the piperidine nitrogen has been investigated. Many single-digit nanomolar MCH R1 antagonists have been identified from this series.
Asunto(s)
Piperidinas/síntesis química , Piperidinas/farmacología , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Humanos , Relación Estructura-ActividadRESUMEN
Biaryl urea lead compound 1 was discovered earlier in our MCH antagonist program. Novel benzimidazole analogues with increased chemical stability, devoid of the potential carcinogenic liability associated with a biarylamine moiety, were synthesized and evaluated to be potent MCH R1 antagonists. Two compounds in this series have demonstrated in vivo efficacy in a rodent obesity model.
Asunto(s)
Fármacos Antiobesidad/síntesis química , Fármacos Antiobesidad/farmacología , Bencimidazoles/síntesis química , Bencimidazoles/farmacología , Peso Corporal/efectos de los fármacos , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Administración Oral , Animales , Modelos Animales de Enfermedad , Diseño de Fármacos , Ratas , Relación Estructura-ActividadRESUMEN
Melanin concentrating hormone (MCH) receptor antagonists have been proposed as potential treatments of obesity. MCH receptor antagonists with a biphenylamine subunit have been reported previously at Schering-Plough. Herein, we report the discovery of bicyclo[4.1.0]heptanes as replacements for the middle phenyl ring of the biphenylamine moiety in order to eliminate its potential mutagenic liability. Structure-activity relationships in this series were found to be very similar to those of the original biphenylamine series, suggesting that the two series have similar binding modes.
Asunto(s)
Compuestos de Aminobifenilo/química , Compuestos Bicíclicos con Puentes/química , Heptanos/química , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Animales , Línea Celular , Cricetinae , Evaluación Preclínica de Medicamentos , Heptanos/farmacología , Ratones , Estructura Molecular , Mutágenos/química , Ratas , Relación Estructura-ActividadRESUMEN
A structure-activity study on benzylpiperidine 1 was accomplished by utilizing high-throughput synthesis. Three focused libraries were designed and synthesized to quickly develop SAR. Further optimization led to the discovery of compound 2, an MCH receptor R1 antagonist with over 400-fold improvement in biological activity over the original lead.
Asunto(s)
Antagonistas de Hormonas/síntesis química , Antagonistas de Hormonas/farmacología , Receptores de la Hormona Hipofisaria/antagonistas & inhibidores , Antagonistas de Hormonas/metabolismo , Espectroscopía de Resonancia Magnética , Receptores de la Hormona Hipofisaria/metabolismo , Relación Estructura-ActividadRESUMEN
Ezetimibe is a potent inhibitor of cholesterol absorption that has been approved for the treatment of hypercholesterolemia, but its molecular target has been elusive. Using a genetic approach, we recently identified Niemann-Pick C1-Like 1 (NPC1L1) as a critical mediator of cholesterol absorption and an essential component of the ezetimibe-sensitive pathway. To determine whether NPC1L1 is the direct molecular target of ezetimibe, we have developed a binding assay and shown that labeled ezetimibe glucuronide binds specifically to a single site in brush border membranes and to human embryonic kidney 293 cells expressing NPC1L1. Moreover, the binding affinities of ezetimibe and several key analogs to recombinant NPC1L1 are virtually identical to those observed for native enterocyte membranes. KD values of ezetimibe glucuronide for mouse, rat, rhesus monkey, and human NPC1L1 are 12,000, 540, 40, and 220 nM, respectively. Last, ezetimibe no longer binds to membranes from NPC1L1 knockout mice. These results unequivocally establish NPC1L1 as the direct target of ezetimibe and should facilitate efforts to identify the molecular mechanism of cholesterol transport.
Asunto(s)
Azetidinas/farmacología , Proteínas de la Membrana/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Proteínas/metabolismo , Animales , Azetidinas/química , Sitios de Unión , Línea Celular , Membrana Celular/metabolismo , Enterocitos/citología , Enterocitos/metabolismo , Ezetimiba , Humanos , Mucosa Intestinal/metabolismo , Intestinos/citología , Macaca mulatta , Proteínas de la Membrana/genética , Proteínas de Transporte de Membrana/deficiencia , Proteínas de Transporte de Membrana/genética , Ratones , Ratones Endogámicos C57BL , Microvellosidades/metabolismo , Enfermedades de Niemann-Pick , Unión Proteica , Proteínas/genética , Ratas , Ratas Sprague-Dawley , Especificidad de la EspecieRESUMEN
OBJECTIVE: To identify and functionally characterize single-nucleotide polymorphisms (SNPs) in melanin-concentrating hormone (MCH)-R1 and -R2. RESEARCH METHODS AND PROCEDURES: The entire coding regions and intron/exon splice junction regions of MCH-R1 and MCH-R2 were sequenced from anonymous white (n=45) and African-American (n=46) individuals. DNA was analyzed, and SNPs were identified using Phred, Phrap, and Consed software. DNA constructs containing MCH-R1 and MCH-R2 SNPs were generated and expressed in CHO cells. The effect of the SNPs in MCH-R1 and MCH-R2 were assessed in receptor binding assays and functional assays measuring changes in intracellular cAMP and Ca2+ levels. RESULTS: We identified 12 SNPs in the MCH-R1 gene. Two of these SNPs are in coding regions, and one produces an arginine-for-glycine substitution at residue 34 in the MCH-R1 sequence. This SNP is present at a minor allele frequency of 15% in the African-American population tested in this study. We identified eight SNPs in the MCH-R2 gene. Four of these SNPs are in coding regions, and two produce amino acid substitutions. Lysine substitutes for arginine at residue 63 of the African-American population, and glutamine substitutes for arginine at residue 152 in whites (minor allele frequency of 2% for both SNPs). No changes in receptor binding or functional signaling were observed with the SNP mutations in MCH-R1 or MCH-R2. DISCUSSION: These data indicate that potential therapeutics designed to act at the MCH receptor are unlikely to have altered effects in subpopulations that express variant forms of MCH-R1 or MCH-R2.