Search Results (18)

Nero Siciliano (NS) is an autochthonous pig breed reared in northeastern Sicily; despite its high-quality meat products, NS is currently endangered. This study aimed to evaluate the genetic variability at nine loci within candidate genes for meat traits—Melanocortin 4 Receptor (MC4R), Ryanodine Receptor 1 (RYR1), Class 3 Phosphoinositide 3-Kinase (PIK3C3) and Leptin (LEP)—to provide useful information for preservation and exploitation of the NS pig breed. Distribution of the genetic variants was assessed in a representative sample of 87 pigs (18 boars and 69 sows) collected in nine farms located in the original breeding area. Genotypes have been determined using PCR-RFLP and Sanger sequencing. Alleles linked to different growth rates and back fat deposition showed high frequencies (MC4R c.175C—0.93; LEP g.3469T—0.91) in the whole sample. Deviations from Hardy–Weinberg equilibrium and different allele distribution in boars and sows were observed. The RYR1 g.1843T allele, associated with Malignant Hyperthermia and Pale Soft Exudative meat defect, was reported in seven heterozygote pigs (q = 0.04) with one farm exhibiting a frequency of 0.29. Our results suggest the need for continuous monitoring of the genetic variants in NS both to maintain high meat quality and eradicate the RYR1 g.1843T allele. Full article

Background/Objectives: Severe early-onset obesity is a complex condition shaped by genetic and metabolic influences. The melanocortin 4 receptor (MC4R) gene plays a crucial role in energy balance, and pathogenic variants are associated with monogenic forms of obesity. This study aims to examine the clinical, metabolic, and genetic characteristics of a patient with severe early-onset obesity and his family, to assess the contribution of an MC4R variant to the observed phenotype. Methods: A 22-year-old male with severe obesity, first recognized at age 3, underwent detailed clinical, metabolic, and genetic evaluations. Laboratory assessments included insulin, lipid profile, uric acid, and IGF-1 levels. Whole-exome sequencing (WES) was performed on the patient and selected family members to identify potential pathogenic variants associated with obesity. Results: Clinical assessment revealed a body mass index (BMI) of 44.68 kg/m², hyperinsulinemia (98.2 µIU/mL), prediabetes (HbA1c: 5.85%), dyslipidemia, hyperuricemia (421.0 µmol/L), and elevated IGF-1 levels (646.7 ng/mL). WES identified a heterozygous MC4R:c.216C>G (p.Asn72Lys) variant present in the patient, his mother, and maternal relatives. This variant, with a population frequency of 0.0004%, is predicted as likely pathogenic by SIFT, MutationTaster, and PrimateAI. However, its segregation pattern suggests a complex inheritance mechanism rather than classical autosomal dominant or recessive inheritance. Conclusions: Early genetic testing in individuals with severe obesity is essential for guiding personalized treatment strategies. Although the MC4R:c.216C>G variant may contribute to the patient’s metabolic profile, further functional studies are required to confirm its pathogenicity and elucidate its role in obesity pathogenesis. Full article

Background: Glucagon-like peptide-2 (GLP-2) is a gut hormone secreted in response to nutrient intake and regulates lipid metabolism in the gut. The present study aims to elucidate the underlying mechanism of GLP-2 in stimulating gut lipid secretion in the fasted state by testing whether GLP-2 signals through the brain’s GLP-2 receptor and melanocortin 4 receptor (MC4R). Methods: Sprague-Dawley rats were implanted with a mesenteric lymph duct cannula for measuring gut lipid secretion and an intracerebroventricular cannula for infusion of a GLP-2R antagonist (GLP-2(11-33)), an MC4R antagonist (SHU9119), or saline as a control. The rat received a lipid infusion into the small intestine and a peritoneal injection of GLP-2 five hours later. Results: Brain administration of a GLP-2R antagonist or an MC4R antagonist attenuated the stimulatory effects of peripheral GLP-2 on lymph triglyceride output. These effects were associated with differential changes in the expression of key genes in jejunal endothelial cells, smooth muscle cells, and neuronal cells. Conclusions: These results support the involvement of central GLP-2R and MC4R in a neural pathway for GLP-2 to mobilize lipids stored in the gut during the post-absorptive state. Full article

Onychostoma macrolepis is not only a protected Cyprinid species in the wild but also an emerging commercial aquaculture fish in China. The objective of this research was to genetically modify the genes associated with commercial traits by CRISPR/Cas9 for the protection and utilization of the germplasm resources of O. macrolepis. To that end, one-cell stage embryos were obtained via hormone-induced ovulation and artificial insemination in O. macrolepis. Eight genes related to body color, growth, intermuscular bone, and sex differentiation were mutated in O. macrolepis using the CRISPR/Cas9 system by microinjection of gRNA/Cas9 mRNA. The optimal dose of gRNA/Cas9 mRNA was determined by injection of different concentrations of tyr (tyrosinase)-gRNA/Cas9 and examination of the mutation rate and hatching rate of embryos. Indels were detected by T7 endonuclease I digestion and Sanger sequencing. F0 mutants with high mutation rates were selected for phenotype analyses. Disruption of body color gene tyr, mpv17 (mitochondrial inner membrane protein MPV17), and csf1ra (colony-stimulating factor 1 receptor, a) resulted in obvious phenotype with decreased or even absence of melanophores, iridophores, and xanthophores, respectively. Mutation of mstnb (myostatin b) led to improved growth performance. Mutation of mc4r (melanocortin 4 receptor) led to no obvious phenotype. Mutation of runx2b (RUNX family transcription factor 2b) and bmp6 (bone morphogenetic protein 6) resulted in decreased or absence of intermuscular bones, as revealed by alizarin red S staining. Mutation of cyp19a1a (cytochrome P450, family 19, subfamily A, polypeptide 1a) resulted in ovarian degeneration as revealed by gonadal histological examination. Therefore, this study successfully obtained mutants with obvious phenotypes of genes associated with body color, growth, intermuscular bone, and sex differentiation by CRISPR/Cas9 in O. macrolepis. Full article

In mammals, the maintenance of energy homeostasis relies on complex mechanisms requiring tight synchronization between peripheral organs and the brain. Thyroid hormones (THs), through their pleiotropic actions, play a central role in these regulations. Hypothyroidism, which is characterized by low circulating TH levels, slows down the metabolism, which leads to a reduction in energy expenditure as well as in lipid and glucose metabolism. The objective of this study was to evaluate whether the metabolic deregulations induced by hypothyroidism could be avoided through regulatory mechanisms involved in metabolic flexibility. To this end, the response to induced hypothyroidism was compared in males from two mouse strains, the wild-derived WSB/EiJ mouse strain characterized by a diet-induced obesity (DIO) resistance due to its high metabolic flexibility phenotype and C57BL/6J mice, which are prone to DIO. The results show that propylthiouracil (PTU)-induced hypothyroidism led to metabolic deregulations, particularly a reduction in hepatic lipid synthesis in both strains. Furthermore, in contrast to the C57BL/6J mice, the WSB/EiJ mice were resistant to the metabolic dysregulations induced by hypothyroidism, mainly through enhanced lipid metabolism in their adipose tissue. Indeed, WSB/EiJ mice compensated for the decrease in hepatic lipid synthesis by mobilizing lipid reserves from white adipose tissue. Gene expression analysis revealed that hypothyroidism stimulated the hypothalamic orexigenic circuit in both strains, but there was unchanged melanocortin 4 receptor (Mc4r) and leptin receptor (LepR) expression in the hypothyroid WSB/EiJ mice strain, which reflects their adaptability to maintain their body weight, in contrast to C57BL/6J mice. Thus, this study showed that WSB/EiJ male mice displayed a resistance to the metabolic dysregulations induced by hypothyroidism through compensatory mechanisms. This highlights the importance of metabolic flexibility in the ability to adapt to disturbed circulating TH levels. Full article

The melanocortin 4 receptor (MC4R) gene plays a central role in regulating energy homeostasis and food intake in livestock, thereby affecting their economic worth and growth. In a previous study, the p.T117M mutation in the sheep MC4R gene, which leads to the transition of threonine to methionine, was found to affect the body weight at six months and the average daily gain in Hu sheep. However, there are still limited studies on the frequency of the sheep p.T117M missense mutation globally, and the underlying cellular mechanism remains elusive. Therefore, this study first used WGS to investigate the distribution of the MC4R gene p.T117M mutation in 652 individuals across 22 breeds worldwide. The results showed that the mutation frequency was higher in European breeds compared with Chinese sheep breeds, particularly in Poll Dorset sheep (mutation frequency > 0.5). The p.T117M mutation occurs in the first extracellular loop of MC4R. Mechanistically, the basal activity of the mutated receptor is significantly increased. Specifically, upon treatment with α-MSH and ACTH ligands, the cAMP and MAPK/ERK signaling activation of M117 MC4R is enhanced. These results indicate that the T117M mutation may change the function of the gene by increasing the constitutive activity and signaling activation of cAMP and MAPK/ERK, and, thus, may regulate the growth traits of sheep. In conclusion, this study delved into the global distribution and underlying cellular mechanisms of the T117M mutation of the MC4R gene, establishing a scientific foundation for breeding sheep with superior growth, thereby contributing to the advancement of the sheep industry. Full article

Bariatric surgery (BS) is considered the most effective intervention for patients with severe obesity and is used to maintain long-term weight loss and glycemic control. The aim of this study was to analyze the effects of genotypes and haplotypes of the fat mass and obesity-associated (FTO) and melanocortin 4 receptor (MC4R) genes on total body weight loss (TBWL), post-surgery weight, and post-BMI after bariatric surgery. We retrospectively selected 101 patients from Bajio High Specialty Regional Hospital, León Guanajuato, México, who underwent Roux-en-Y gastric bypass (RYGB) to determine their body mass index (BMI), blood pressure, biochemical characteristics, and comorbidities. Post-surgery, patients were referred for registered anthropometry and blood pressure. Glucose, lipid and hepatic profiles, and insulin, leptin, and ghrelin levels were measured, and rs9939609, rs9930506, and rs1421085 FTO and rs17782313 MC4R polymorphisms were genotyped. Six (4–8) years after BS, post-surgery weight was greater in carriers of the rs9939609 and rs1421085 risk genotypes. TBWL was lower for the rs9930506 and rs1421085 risk genotypes. Insulin and HOMA-IR were greater in patients with the three FTO polymorphisms. There were significant interaction effects of the rs9930506 and rs1421085 FTO risk genotypes on weight and BMI in response to BS. No association was found with the MC4R polymorphism. The genotypes and haplotypes of the FTO gene influence post-surgery weight, TBWL, insulin levels, and HOMA-IR. Full article

Obesity is a multifactorial disease whose onset and development are shaped by the individual genetic background. The melanocortin 4 receptor gene (MC4R) is involved in the regulation of food intake and energy expenditure. Some of the single nucleotide polymorphisms (SNPs) of this gene are related to obesity and metabolic risk factors. The present study was undertaken to assess the relationship between three polymorphism SNPs, namely, rs17782313, rs17773430 and rs34114122, and obesity and metabolic risk factors. One hundred seventy-eight children with obesity aged between 7 and 16 years were studied to determine anthropometric variables and biochemical and inflammatory parameters. Our results highlight that metabolic risk factors, especially alterations in carbohydrate metabolism, were related to rs17782313. The presence of the minor C allele in the three variants (C–C–C) was significantly associated with anthropometric measures indicative of obesity, such as the body mass and fat mass indexes, and increased the values of insulinemia to 21.91 µIU/mL with respect to the wild type values. Our study suggests that the C–C–C haplotype of the SNPs rs17782313, rs17773430 and rs34114122 of the MC4R gene potentiates metabolic risk factors at early ages in children with obesity. Full article

In teleost, as in other vertebrates, stress affects reproduction. A key component of the stress response is the pituitary secretion of the adrenocorticotropic hormone (ACTH), which binds to the melanocortin 2 receptor (MC2R) in the adrenal glands and activates cortisol biosynthesis. In zebrafish, Mc2r was identified in male and female gonads, while ACTH has been shown to have a physiological role in modulating reproductive activity. In this study, the hypothesis that other melanocortins may also affect how the zebrafish gonadal function is explored, specifically steroid biosynthesis, given the presence of members of the melanocortin signaling system in zebrafish gonads. Using cell culture, expression analysis, and cellular localization of gene expression, our new observations demonstrated that melanocortin receptors, accessory proteins, antagonists, and agonists are expressed in both the ovary and testis of zebrafish (n = 4 each sex). Moreover, melanocortin peptides modulate both basal and gonadotropin-stimulated steroid release from zebrafish gonads (n = 15 for males and n = 50 for females). In situ hybridization in ovaries (n = 3) of zebrafish showed mc1r and mc4r in follicular cells and adjacent to cortical alveoli in the ooplasm of previtellogenic and vitellogenic oocytes. In zebrafish testes (n = 3), mc4r and mc1r were detected exclusively in germ cells, specifically in spermatogonia and spermatocytes. Our results suggest that melanocortins are, directly or indirectly, involved in the endocrine control of vitellogenesis in females, through modulation of estradiol synthesis via autocrine or paracrine actions in zebrafish ovaries. Adult zebrafish testes were sensitive to low doses of ACTH, eliciting testosterone production, which indicates a potential role of this peptide as a paracrine regulator of testicular function. Full article

Obesity is a complex multifactorial disorder with genetic and environmental factors. There is an increase in the worldwide prevalence of obesity in both developed and developing countries. The development of genome-wide association studies (GWAS) and next-generation sequencing (NGS) has increased the discovery of genetic associations and awareness of monogenic and polygenic causes of obesity. The genetics of obesity could be classified into syndromic and non-syndromic obesity. Prader–Willi, fragile X, Bardet–Biedl, Cohen, and Albright Hereditary Osteodystrophy (AHO) syndromes are examples of syndromic obesity, which are associated with developmental delay and early onset obesity. Non-syndromic obesity could be monogenic, polygenic, or chromosomal in origin. Monogenic obesity is caused by variants of single genes while polygenic obesity includes several genes with the involvement of members of gene families. New advances in genetic testing have led to the identification of obesity-related genes. Leptin (LEP), the leptin receptor (LEPR), proopiomelanocortin (POMC), prohormone convertase 1 (PCSK1), the melanocortin 4 receptor (MC4R), single-minded homolog 1 (SIM1), brain-derived neurotrophic factor (BDNF), and the neurotrophic tyrosine kinase receptor type 2 gene (NTRK2) have been reported as causative genes for obesity. NGS is now in use and emerging as a useful tool to search for candidate genes for obesity in clinical settings. Full article

Melanocortin 4 receptor (MC4R) is part of the leptin-melanocortin pathway and plays an essential role in mediating energy homeostasis. Mutations in the MC4R are the most frequent monogenic cause for obesity. Due to increasing numbers of people with excess body weight, the MC4R has become a target of interest in the search of treatment options. We have previously reported that the MC4R forms homodimers, affecting receptor G_s signaling properties. Recent studies introducing setmelanotide, a novel synthetic MC4R agonist, suggest a predominant role of the G_q/11 pathway regarding weight regulation. In this study, we analyzed effects of inhibiting homodimerization on G_q/11 signaling using previously reported MC4R/CB1R chimeras. NanoBRET^TM studies to determine protein–protein interaction were conducted, confirming decreased homodimerization capacities of chimeric receptors in HEK293 cells. G_q/11 signaling of chimeric receptors was analyzed using luciferase-based reporter gene (NFAT) assays. Results demonstrate an improvement of alpha-MSH-induced NFAT signaling of chimeras, reaching the level of setmelanotide signaling at wild-type MC4R (MC4R-WT). In summary, our study shows that inhibiting homodimerization has a setmelanotide-like effect on G_q/11 signaling, with chimeric receptors presenting increased potency compared to MC4R-WT. These findings indicate the potential of inhibiting MC4R homodimerization as a therapeutic target to treat obesity. Full article

The melanocortin receptors are G-protein-coupled receptors, which are essential components of the hypothalamic–pituitary–adrenal axis, and they mediate the actions of melanocortins (melanocyte-stimulating hormones: α-MSH, β-MSH, and γ-MSH) as well as the adrenocorticotropin hormone (ACTH) in skin pigmentation, adrenal steroidogenesis, and stress response. Three melanocortin receptor genes (MC1R, MC2R, and MC5R) contribute to the risk of major depressive disorder (MDD), and one melanocortin receptor gene (MC4R) contributes to the risk of type 2 diabetes (T2D). MDD increases T2D risk in drug-naïve patients; thus, MDD and T2D commonly coexist. The five melanocortin receptor genes might confer risk for both disorders. However, they have never been investigated jointly to evaluate their potential contributing roles in the MDD-T2D comorbidity, specifically within families. In 212 Italian families with T2D and MDD, we tested 11 single nucleotide polymorphisms (SNPs) in the MC1R gene, 9 SNPs in MC2R, 3 SNPs in MC3R, 4 SNPs in MC4R, and 2 SNPs in MC5R. The testing used 2-point parametric linkage and linkage disequilibrium (LD) (i.e., association) analysis with four models (dominant with complete penetrance (D1), dominant with incomplete penetrance (D2), recessive with complete penetrance (R1), and recessive with incomplete penetrance (R2)). We detected significant (p ≤ 0.05) linkage and/or LD (i.e., association) to/with MDD for one SNP in MC2R (rs111734014) and one SNP in MC5R (rs2236700), and to/with T2D for three SNPs in MC1R (rs1805007 and rs201192930, and rs2228479), one SNP in MC2R (rs104894660), two SNPs in MC3R (rs3746619 and rs3827103), and one SNP in MC4R genes (Chr18-60372302). The linkage/LD/association was significant across different linkage patterns and different modes of inheritance. All reported variants are novel in MDD and T2D. This is the first study to report risk variants in MC1R, MC2R, and MC3R genes in T2D. MC2R and MC5R genes are replicated in MDD, with one novel variant each. Within our dataset, only the MC2R gene appears to confer risk for both MDD and T2D, albeit with different risk variants. To further clarity the role of the melanocortin receptor genes in MDD-T2D, these findings should be sought among other ethnicities as well. Full article

Obesity is one of the main public health problems in Mexico and the world and one from which a large number of pathologies derive. Single nucleotide polymorphisms (SNPs) of various genes have been studied and proven to contribute to the development of multiple diseases. SNPs of the leptin pathway have been associated with the control of hunger and energy expenditure as well as with obesity and type 2 diabetes mellitus. Therefore, the present work focused on determining the association between anthropometric markers and biochemical and dietary factors related to obesity and SNPs of leptin pathway genes, such as the leptin gene (LEP), the leptin receptor (LEPR), proopiomelanocortin (POMC), prohormone convertase 1 (PCSK1), and the melanocortin 4 receptor (MC4R). A population of 574 young Mexican adults of both sexes, aged 19 years old on average and without metabolic disorders previously diagnosed, underwent a complete medical and nutritional evaluation, biochemical determination, and DNA extraction from the blood; DNA samples were subsequently genotyped. Association analyses between anthropometric, biochemical, and dietary variables with SNPs were performed using binary logistic regressions (p-value = 0.05). Although the sampled population did not have previously diagnosed diseases, the evaluation results showed that 33% were overweight or obese according to BMI and 64% had non-clinically elevated levels of body fat. From the 74 SNP markers analyzed from the five previously mentioned genes, 62 showed polymorphisms within the sampled population, and only 35 of these had significant associations with clinical variables. The risk associations (OR > 1) occurred between clinical markers with elevated values for waist circumference, waist–height index, BMI, body fat percentage, glucose levels, insulin levels, HOMA-IR, triglyceride levels, cholesterol levels, LDL-c, low HDL-c, carbohydrate intake, and protein intake and SNPs of the LEP, LEPR, PCSK1, and MC4R genes. On the other hand, the protective associations (OR < 1) were associated with markers including elevated values for insulin, HOMA-IR, cholesterol, c-LDL, energy intake > 2440 Kcal/day, and lipid intake and SNPs of the LEP and LEPR genes and POMC. The present study describes associations between SNPs in leptin pathway genes, revealing positive and negative interactions between reported SNPs and the clinical markers related to obesity in a sampled Mexican population. Hence, our results open the door for the further study of new genetic variants and their influence on obesity. Full article

FGF21 is a promising candidate for treating obesity, diabetes, and NAFLD; however, some of its pharmacological effects are sex-specific in mice with the A^y mutation that evokes melanocortin receptor 4 blockade, obesity, and hepatosteatosis. This suggests that the ability of FGF21 to correct melanocortin obesity may depend on sex. This study compares FGF21 action on food intake, locomotor activity, gene expression, metabolic characteristics, and liver state in obese A^y males and females. A^y mice were administered FGF21 for seven days, and metabolic parameters and gene expression in different tissues were assessed. Placebo-treated females were more obese than males and had lower levels of blood insulin and liver triglycerides, and higher expression of genes for insulin signaling in the liver, white adipose tissue (WAT) and muscles, and pro-inflammatory cytokines in the liver. FGF21 administration did not affect body weight, and increased food intake, locomotor activity, expression of Fgf21 and Ucp1 in brown fat and genes related to lipolysis and insulin action in WAT regardless of sex; however, it decreased hyperinsulinemia and hepatic lipid accumulation and increased muscle expression of Cpt1 and Irs1 only in males. Thus, FGF21’s beneficial effects on metabolic disorders associated with melanocortin obesity are more pronounced in males. Full article

The melanocortin receptor 4 (MC4R) signaling system consists of MC4R, MC4R ligands [melanocyte-stimulating hormone (MSH), adrenocorticotropin (ACTH), agouti-related protein (AgRP)], and melanocortin-2 receptor accessory protein 2 (MRAP2), and it has been proposed to play important roles in feeding and growth in vertebrates. However, the expression and functionality of this system have not been fully characterized in teleosts. Here, we cloned tilapia MC4R, MRAP2b, AgRPs (AgRP, AgRP2), and POMCs (POMCa1, POMCb) genes and characterized the interaction of tilapia MC4R with MRAP2b, AgRP, α-MSH, and ACTH in vitro. The results indicate the following. (1) Tilapia MC4R, MRAP2b, AgRPs, and POMCs share high amino acid identity with their mammalian counterparts. (2) Tilapia MRAP2b could interact with MC4R expressed in CHO cells, as demonstrated by Co-IP assay, and thus decrease MC4R constitutive activity and enhance its sensitivity to ACTH_1-40. (3) As in mammals, AgRP can function as an inverse agonist and antagonist of MC4R, either in the presence or absence of MRAP2b. These data, together with the co-expression of MC4R, MRAP2b, AgRPs, and POMCs in tilapia hypothalamus, suggest that as in mammals, ACTH/α-MSH, AgRP, and MRAP2 can interact with MC4R to control energy balance and thus play conserved roles in the feeding and growth of teleosts. Full article