OBJECTIVETo screen the coding region of melanocortin-4 receptor gene (MC4R) for mutations in children, analyze the association of the identified variants with obesity-related phenotypes, and predict the potential functions of the identified variants.

METHODSA case-control study was conducted in 160 severely obese children and 100 normal-weight controls, all aged 7-18 years. Their anthropometric data were collected and blood tests were performed. The coding region of MC4R gene was screened by polymerase chain reaction (PCR), single strand conformation polymorphism and sequencing, and the potential functions of the identified variants were predicted by related online databases.

RESULTSThree heterozygous missense mutations were identified in obese children (Val95Ile, Val166Ile and Val179Ala), and one heterozygous missense mutation was found in controls (Met218Thr). Val103Ile variant was found to be carried by seven subjects in the obese group and six in the control group (P>0.05). Val179Ala was a newly identified heterozygous mutation. No significant differences in BMI, weight, waist circumstance, hip circumstance, serum lipid parameters, fasting glucose, and body fat percentage were found between Val95Ile, Val166Ile or Val179Ala mutation carriers and non-carriers in obese children. The function prediction of the variants showed that all the five identified variants influenced the protein function.

CONCLUSIONSFive variants were identified in the coding region of MC4R gene, among which Val179Ala was newly identified. All the five variants might influence the protein function as evidenced by online prediction.

Adolescent ; Child ; Female ; Humans ; Male ; Mutation ; Obesity ; genetics ; Receptor, Melanocortin, Type 4 ; genetics ; physiology

There is now widespread recognition that the continuing increase in the prevalence of obesity seen in many countries is likely to have major adverse effects on public health. And genetic factors are important that make individual difference of obesity's severity and expressive time. So it is important roles of study for obesity related genes that have been necessary to development of drug and program to diet and exercise for obesity. In these studies, they were discovered that there are several pattern of genes associated obesity. Especially, monogenic gene is important that is more easier for development of drug and program to diet and exercise for obesity. In instance, leptin, leptin receptor, carboxypeptidase, agouti, melanocortin 4 receptor (MC4R) and agouti-related protein etc. was included monogenic genes. Their mutation or blockage of pathway makes severe and early obesity. Mutation of MC4R is the most common monogenic genes and approximately 6% in severe and early obese patients. We conducted DNA analysis in severe obese patients, and discovered an obese patient associated with MC4R mutation at first in Korea.
Agouti-Related Protein ; Diet ; DNA ; Humans ; Individuality ; Korea ; Leptin ; Obesity ; Prevalence ; Public Health ; Receptor, Melanocortin, Type 4* ; Receptors, Leptin

Adult ; Asian Continental Ancestry Group ; genetics ; Female ; Humans ; Male ; Mutation ; Obesity ; genetics ; Receptor, Melanocortin, Type 4 ; genetics ; Young Adult

The current study was designed to examine the effects of intracerebroventricular injections of SHU9119 [a nonselective melanocortin receptor (McR) antagonist] and MCL0020 (a selective McR antagonist) on the serotonin-induced eating and drinking responses of broiler cockerels deprived of food for 24 h (FD24). For Experiment 1, the chickens were intracerebroventricularly injected with 2.5, 5, and 10 microg serotonin. In Experiment 2, the chickens received 2 nmol SHU9119 before being injected with 10 microg serotonin. For Experiment 3, the chickens were given 10 microg serotonin after receiving 2 nmol MCL0020, and the level of food and water intake was determined 3 h post-injection. Results of this study showed that serotonin decreased food intake but increased water intake among the FD24 broiler cockerels and that these effects occurred in a dose-dependent manner. The inhibitory effect of serotonin on food intake was significantly attenuated by pretreatment with SHU9119 and MCL0020. However, the stimulatory effect of serotonin on water intake was not altered by this pretreatment. These results suggest that serotonin hypophagia and hyperdipsia were mediated by different mechanisms in the central nervous system, and that serotonin required downstream activation of McRs to promote hypophagia but not hyperdipsia in the FD24 chickens.
Animals ; Chickens ; Dose-Response Relationship, Drug ; Drinking Behavior/*drug effects ; Feeding Behavior/*drug effects ; Food Deprivation ; Injections, Intraventricular/veterinary ; Male ; Melanocyte-Stimulating Hormones/*pharmacology ; Oligopeptides/*pharmacology ; Receptor, Melanocortin, Type 3/*antagonists & inhibitors ; Receptor, Melanocortin, Type 4/*antagonists & inhibitors ; Serotonin/pharmacology

Obesity provokes many serious human diseases, including various cardiovascular diseases and diabetes. Body mass index (BMI) is a highly heritable trait that is broadly used to diagnose obesity. To identify genetic loci associated with obesity in Asians, we conducted a genome-wide association study (GWAS) of a population of Korean adults (n=6,742, age 40~60 years) and detected six BMI risk loci (TNR, FAM124B, RGS12, NFE2L3, MC4R and FTO) having p<1x10(-5). However, in the replication study, only melanocortin 4 receptor gene (MC4R) (rs9946888, p=4.58x10(-7)) was replicated with marginal significance (p<0.05) in the second cohort (n=5,102, age 40~60 years). This study indicates that each locus associated with BMI has very weak genetic effect.
Adult ; Asian Continental Ancestry Group ; Body Mass Index ; Cardiovascular Diseases ; Cohort Studies ; Genetic Loci ; Genome-Wide Association Study ; Humans ; Obesity ; Receptor, Melanocortin, Type 4

Obesity has become a severe public health problem across the world, and seriously affects the health and life quality of human beings. Here we generated lepr and mc4r mutant zebrafish via the CRISPR/Cas9 technique, and performed morphological and functional characterizations of those mutants. We observed that there was no significant phenotypic difference between homozygous mutants and wild-type controls before 2.5 months post-fertilization (mpf). However, the adult leprand mc4rindividuals displayed increased food intake, heavier weight, and higher body fat percentage, the characteristics of obesity phenotypes. Blood glucose test showed that overfeeding induced significantly impaired glucose tolerance in adult leprand mc4rzebrafish. Furthermore, we analyzed 76 energy metabolism-related transcripts in leprand mc4rzebrafish livers by using real-time RT-PCR, and compared the results with the published microarray data of Lepmouse livers, and found that the changes in the expression of insulin/IGF signaling (IIS) pathway genes in leprzebrafish and Lepmouse were positively correlated, suggesting that the IIS pathway maintains functional conservation between zebrafish and mammals during the evolution of the obesity-regulating molecule network.
Animals ; CRISPR-Cas Systems ; Gene Knockout Techniques ; Insulin ; metabolism ; Leptin ; Mutation ; Obesity ; genetics ; Receptor, Melanocortin, Type 4 ; genetics ; Receptors, Leptin ; genetics ; Signal Transduction ; Zebrafish ; Zebrafish Proteins ; genetics

OBJECTIVETo investigate how F261S mutation identified from Chinese obese patients affects the function of melanocortin 4 receptor (MC4R) and to analyze the obesity-related phenotypes in subjects carrying the F261S mutation.

METHODSF261S mutant of MC4R was generated by site-directed mutagenesis. Plasmids encoding wild-type or F261S mutant of MC4R were transfected into HEK293 and COS-7 cells to examine their functional characteristics. Signaling properties of F261S MC4R were assessed by measuring intracellular cAMP levels in response to alpha-MSH stimulation. Cell surface expression of F261S MC4R was compared with that of wild-type MC4R. Clinical examinations were performed in subjects carrying F261S mutation and in non-mutated controls.

RESULTSThe alpha-MSH-stimulated reporter gene activity was significantly reduced in cells expressing F261S MC4R, with a maximal response equal to 57% of wild-type MC4R. The F261S mutation also led to a significant change in the Es50 value compared with the wild-type receptor (P<0.01). Immunofluorescent assay revealed a marked reduction in plasma membrane localization of the MC4R in cells expressing the F261S mutant receptor. The resting metabolic rate and fat composition of the mutant carriers were not significantly different from those of the non-mutated obese controls.

CONCLUSIONSThe decreased response to alpha-MSH due to the intracellular retention of MC4R may cause early-onset obesity in the F261S pedigree of Chinese.

Adult ; Age of Onset ; Aged ; Animals ; COS Cells ; Cercopithecus aethiops ; Child ; China ; Female ; Humans ; Male ; Middle Aged ; Mutation ; Obesity ; epidemiology ; metabolism ; Pedigree ; Receptor, Melanocortin, Type 4 ; genetics ; metabolism

Animals ; Gene Expression Profiling ; Humans ; Leptin ; genetics ; Obesity ; genetics ; Polymorphism, Genetic ; Receptor, Melanocortin, Type 4 ; genetics ; Receptors, Adrenergic, beta-3 ; genetics

BACKGROUND: The melanocortin 4 receptor (MC4R) is involved in the regulation of homeostatic energy balance by the hypothalamus. Recent reports showed that MC4R can also control the motivation for food in association with a brain reward system, such as dopamine. We investigated the expression levels of MC4R and the dopamine D2 receptor (D2R), which is known to be related to food rewards, in both the hypothalamus and brain regions involved in food rewards. METHODS: We examined the expression levels of D2R and MC4R by dual immunofluorescence histochemistry in hypothalamic regions and in the bed nucleus of the stria terminalis (BNST), the central amygdala, and the ventral tegmental area of transgenic mice expressing enhanced green fluorescent protein under the control of the D2R gene. RESULTS: In the hypothalamic area, significant coexpression of MC4R and D2R was observed in the arcuate nucleus. We observed a significant coexpression of D2R and MC4R in the BNST, which has been suggested to be an important site for food reward. CONCLUSION: We suggest that MC4R and D2R function in the hypothalamus for control of energy homeostasis and that within the brain regions related with rewards, such as the BNST, the melanocortin system works synergistically with dopamine for the integration of food motivation in the control of feeding behaviors.
Amygdala ; Animals ; Arcuate Nucleus ; Brain* ; Dopamine* ; Eating* ; Feeding Behavior ; Fluorescent Antibody Technique ; Homeostasis ; Hypothalamus ; Mice ; Mice, Transgenic ; Motivation ; Obesity ; Receptor, Melanocortin, Type 4* ; Receptors, Dopamine D2* ; Reward ; Ventral Tegmental Area

The rostral ventromedial medulla (RVM) is a prominent component of the descending modulatory system involved in the control of spinal nociceptive transmission. In the current study, we investigated melanocortin-4 receptor (MC4R) expression in the RVM, where the neurons involved in modulation of nociception reside. Using a line of mice expressing green fluorescent protein (GFP) under the control of the MC4R promoter, we found a large number of GFP-positive neurons in the RVM [nucleus raphe magnus (NRM) and nucleus gigantocellularis pars α (NGCα)]. Fluorescence immunohistochemistry revealed that approximately 10% of MC4R-GFP-positive neurons coexpressed tyrosine hydroxylase, indicating that they were catecholaminergic, whereas 50%-75% of those coexpressed tryptophan hydroxylase, indicating that they were serotonergic. Our findings support the hypothesis that MC4R signaling in RVM may modulate the activity of serotonergic sympathetic outflow sensitive to nociceptive signals, and that MC4R signaling in RVM may contribute to the descending modulation of nociceptive transmission.
Animals ; Female ; Male ; Medulla Oblongata ; cytology ; metabolism ; Mice ; Mice, Transgenic ; Neural Pathways ; cytology ; metabolism ; Neurons, Afferent ; cytology ; metabolism ; Nociception ; physiology ; Receptor, Melanocortin, Type 4 ; genetics ; metabolism ; Serotonergic Neurons ; metabolism ; Tyrosine 3-Monooxygenase ; metabolism